Adding upstream version 5.28.2+dfsg1+~cs23.11.12.3.upstream/5.28.2+dfsg1+_cs23.11.12.3upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

14 files changed, 8031 insertions, 0 deletions

diff --git a/lib/fetch/LICENSE b/lib/fetch/LICENSE
new file mode 100644
index 0000000..2943500
--- /dev/null
+++ b/lib/fetch/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2020 Ethan Arrowood
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/lib/fetch/body.js b/lib/fetch/body.js
new file mode 100644
index 0000000..fd8481b
--- /dev/null
+++ b/lib/fetch/body.js
@@ -0,0 +1,605 @@
+'use strict'
+
+const Busboy = require('@fastify/busboy')
+const util = require('../core/util')
+const {
+  ReadableStreamFrom,
+  isBlobLike,
+  isReadableStreamLike,
+  readableStreamClose,
+  createDeferredPromise,
+  fullyReadBody
+} = require('./util')
+const { FormData } = require('./formdata')
+const { kState } = require('./symbols')
+const { webidl } = require('./webidl')
+const { DOMException, structuredClone } = require('./constants')
+const { Blob, File: NativeFile } = require('buffer')
+const { kBodyUsed } = require('../core/symbols')
+const assert = require('assert')
+const { isErrored } = require('../core/util')
+const { isUint8Array, isArrayBuffer } = require('util/types')
+const { File: UndiciFile } = require('./file')
+const { parseMIMEType, serializeAMimeType } = require('./dataURL')
+
+let ReadableStream = globalThis.ReadableStream
+
+/** @type {globalThis['File']} */
+const File = NativeFile ?? UndiciFile
+const textEncoder = new TextEncoder()
+const textDecoder = new TextDecoder()
+
+// https://fetch.spec.whatwg.org/#concept-bodyinit-extract
+function extractBody (object, keepalive = false) {
+  if (!ReadableStream) {
+    ReadableStream = require('stream/web').ReadableStream
+  }
+
+  // 1. Let stream be null.
+  let stream = null
+
+  // 2. If object is a ReadableStream object, then set stream to object.
+  if (object instanceof ReadableStream) {
+    stream = object
+  } else if (isBlobLike(object)) {
+    // 3. Otherwise, if object is a Blob object, set stream to the
+    //    result of running object’s get stream.
+    stream = object.stream()
+  } else {
+    // 4. Otherwise, set stream to a new ReadableStream object, and set
+    //    up stream.
+    stream = new ReadableStream({
+      async pull (controller) {
+        controller.enqueue(
+          typeof source === 'string' ? textEncoder.encode(source) : source
+        )
+        queueMicrotask(() => readableStreamClose(controller))
+      },
+      start () {},
+      type: undefined
+    })
+  }
+
+  // 5. Assert: stream is a ReadableStream object.
+  assert(isReadableStreamLike(stream))
+
+  // 6. Let action be null.
+  let action = null
+
+  // 7. Let source be null.
+  let source = null
+
+  // 8. Let length be null.
+  let length = null
+
+  // 9. Let type be null.
+  let type = null
+
+  // 10. Switch on object:
+  if (typeof object === 'string') {
+    // Set source to the UTF-8 encoding of object.
+    // Note: setting source to a Uint8Array here breaks some mocking assumptions.
+    source = object
+
+    // Set type to `text/plain;charset=UTF-8`.
+    type = 'text/plain;charset=UTF-8'
+  } else if (object instanceof URLSearchParams) {
+    // URLSearchParams
+
+    // spec says to run application/x-www-form-urlencoded on body.list
+    // this is implemented in Node.js as apart of an URLSearchParams instance toString method
+    // See: https://github.com/nodejs/node/blob/e46c680bf2b211bbd52cf959ca17ee98c7f657f5/lib/internal/url.js#L490
+    // and https://github.com/nodejs/node/blob/e46c680bf2b211bbd52cf959ca17ee98c7f657f5/lib/internal/url.js#L1100
+
+    // Set source to the result of running the application/x-www-form-urlencoded serializer with object’s list.
+    source = object.toString()
+
+    // Set type to `application/x-www-form-urlencoded;charset=UTF-8`.
+    type = 'application/x-www-form-urlencoded;charset=UTF-8'
+  } else if (isArrayBuffer(object)) {
+    // BufferSource/ArrayBuffer
+
+    // Set source to a copy of the bytes held by object.
+    source = new Uint8Array(object.slice())
+  } else if (ArrayBuffer.isView(object)) {
+    // BufferSource/ArrayBufferView
+
+    // Set source to a copy of the bytes held by object.
+    source = new Uint8Array(object.buffer.slice(object.byteOffset, object.byteOffset + object.byteLength))
+  } else if (util.isFormDataLike(object)) {
+    const boundary = `----formdata-undici-0${`${Math.floor(Math.random() * 1e11)}`.padStart(11, '0')}`
+    const prefix = `--${boundary}\r\nContent-Disposition: form-data`
+
+    /*! formdata-polyfill. MIT License. Jimmy Wärting <https://jimmy.warting.se/opensource> */
+    const escape = (str) =>
+      str.replace(/\n/g, '%0A').replace(/\r/g, '%0D').replace(/"/g, '%22')
+    const normalizeLinefeeds = (value) => value.replace(/\r?\n|\r/g, '\r\n')
+
+    // Set action to this step: run the multipart/form-data
+    // encoding algorithm, with object’s entry list and UTF-8.
+    // - This ensures that the body is immutable and can't be changed afterwords
+    // - That the content-length is calculated in advance.
+    // - And that all parts are pre-encoded and ready to be sent.
+
+    const blobParts = []
+    const rn = new Uint8Array([13, 10]) // '\r\n'
+    length = 0
+    let hasUnknownSizeValue = false
+
+    for (const [name, value] of object) {
+      if (typeof value === 'string') {
+        const chunk = textEncoder.encode(prefix +
+          `; name="${escape(normalizeLinefeeds(name))}"` +
+          `\r\n\r\n${normalizeLinefeeds(value)}\r\n`)
+        blobParts.push(chunk)
+        length += chunk.byteLength
+      } else {
+        const chunk = textEncoder.encode(`${prefix}; name="${escape(normalizeLinefeeds(name))}"` +
+          (value.name ? `; filename="${escape(value.name)}"` : '') + '\r\n' +
+          `Content-Type: ${
+            value.type || 'application/octet-stream'
+          }\r\n\r\n`)
+        blobParts.push(chunk, value, rn)
+        if (typeof value.size === 'number') {
+          length += chunk.byteLength + value.size + rn.byteLength
+        } else {
+          hasUnknownSizeValue = true
+        }
+      }
+    }
+
+    const chunk = textEncoder.encode(`--${boundary}--`)
+    blobParts.push(chunk)
+    length += chunk.byteLength
+    if (hasUnknownSizeValue) {
+      length = null
+    }
+
+    // Set source to object.
+    source = object
+
+    action = async function * () {
+      for (const part of blobParts) {
+        if (part.stream) {
+          yield * part.stream()
+        } else {
+          yield part
+        }
+      }
+    }
+
+    // Set type to `multipart/form-data; boundary=`,
+    // followed by the multipart/form-data boundary string generated
+    // by the multipart/form-data encoding algorithm.
+    type = 'multipart/form-data; boundary=' + boundary
+  } else if (isBlobLike(object)) {
+    // Blob
+
+    // Set source to object.
+    source = object
+
+    // Set length to object’s size.
+    length = object.size
+
+    // If object’s type attribute is not the empty byte sequence, set
+    // type to its value.
+    if (object.type) {
+      type = object.type
+    }
+  } else if (typeof object[Symbol.asyncIterator] === 'function') {
+    // If keepalive is true, then throw a TypeError.
+    if (keepalive) {
+      throw new TypeError('keepalive')
+    }
+
+    // If object is disturbed or locked, then throw a TypeError.
+    if (util.isDisturbed(object) || object.locked) {
+      throw new TypeError(
+        'Response body object should not be disturbed or locked'
+      )
+    }
+
+    stream =
+      object instanceof ReadableStream ? object : ReadableStreamFrom(object)
+  }
+
+  // 11. If source is a byte sequence, then set action to a
+  // step that returns source and length to source’s length.
+  if (typeof source === 'string' || util.isBuffer(source)) {
+    length = Buffer.byteLength(source)
+  }
+
+  // 12. If action is non-null, then run these steps in in parallel:
+  if (action != null) {
+    // Run action.
+    let iterator
+    stream = new ReadableStream({
+      async start () {
+        iterator = action(object)[Symbol.asyncIterator]()
+      },
+      async pull (controller) {
+        const { value, done } = await iterator.next()
+        if (done) {
+          // When running action is done, close stream.
+          queueMicrotask(() => {
+            controller.close()
+          })
+        } else {
+          // Whenever one or more bytes are available and stream is not errored,
+          // enqueue a Uint8Array wrapping an ArrayBuffer containing the available
+          // bytes into stream.
+          if (!isErrored(stream)) {
+            controller.enqueue(new Uint8Array(value))
+          }
+        }
+        return controller.desiredSize > 0
+      },
+      async cancel (reason) {
+        await iterator.return()
+      },
+      type: undefined
+    })
+  }
+
+  // 13. Let body be a body whose stream is stream, source is source,
+  // and length is length.
+  const body = { stream, source, length }
+
+  // 14. Return (body, type).
+  return [body, type]
+}
+
+// https://fetch.spec.whatwg.org/#bodyinit-safely-extract
+function safelyExtractBody (object, keepalive = false) {
+  if (!ReadableStream) {
+    // istanbul ignore next
+    ReadableStream = require('stream/web').ReadableStream
+  }
+
+  // To safely extract a body and a `Content-Type` value from
+  // a byte sequence or BodyInit object object, run these steps:
+
+  // 1. If object is a ReadableStream object, then:
+  if (object instanceof ReadableStream) {
+    // Assert: object is neither disturbed nor locked.
+    // istanbul ignore next
+    assert(!util.isDisturbed(object), 'The body has already been consumed.')
+    // istanbul ignore next
+    assert(!object.locked, 'The stream is locked.')
+  }
+
+  // 2. Return the results of extracting object.
+  return extractBody(object, keepalive)
+}
+
+function cloneBody (body) {
+  // To clone a body body, run these steps:
+
+  // https://fetch.spec.whatwg.org/#concept-body-clone
+
+  // 1. Let « out1, out2 » be the result of teeing body’s stream.
+  const [out1, out2] = body.stream.tee()
+  const out2Clone = structuredClone(out2, { transfer: [out2] })
+  // This, for whatever reasons, unrefs out2Clone which allows
+  // the process to exit by itself.
+  const [, finalClone] = out2Clone.tee()
+
+  // 2. Set body’s stream to out1.
+  body.stream = out1
+
+  // 3. Return a body whose stream is out2 and other members are copied from body.
+  return {
+    stream: finalClone,
+    length: body.length,
+    source: body.source
+  }
+}
+
+async function * consumeBody (body) {
+  if (body) {
+    if (isUint8Array(body)) {
+      yield body
+    } else {
+      const stream = body.stream
+
+      if (util.isDisturbed(stream)) {
+        throw new TypeError('The body has already been consumed.')
+      }
+
+      if (stream.locked) {
+        throw new TypeError('The stream is locked.')
+      }
+
+      // Compat.
+      stream[kBodyUsed] = true
+
+      yield * stream
+    }
+  }
+}
+
+function throwIfAborted (state) {
+  if (state.aborted) {
+    throw new DOMException('The operation was aborted.', 'AbortError')
+  }
+}
+
+function bodyMixinMethods (instance) {
+  const methods = {
+    blob () {
+      // The blob() method steps are to return the result of
+      // running consume body with this and the following step
+      // given a byte sequence bytes: return a Blob whose
+      // contents are bytes and whose type attribute is this’s
+      // MIME type.
+      return specConsumeBody(this, (bytes) => {
+        let mimeType = bodyMimeType(this)
+
+        if (mimeType === 'failure') {
+          mimeType = ''
+        } else if (mimeType) {
+          mimeType = serializeAMimeType(mimeType)
+        }
+
+        // Return a Blob whose contents are bytes and type attribute
+        // is mimeType.
+        return new Blob([bytes], { type: mimeType })
+      }, instance)
+    },
+
+    arrayBuffer () {
+      // The arrayBuffer() method steps are to return the result
+      // of running consume body with this and the following step
+      // given a byte sequence bytes: return a new ArrayBuffer
+      // whose contents are bytes.
+      return specConsumeBody(this, (bytes) => {
+        return new Uint8Array(bytes).buffer
+      }, instance)
+    },
+
+    text () {
+      // The text() method steps are to return the result of running
+      // consume body with this and UTF-8 decode.
+      return specConsumeBody(this, utf8DecodeBytes, instance)
+    },
+
+    json () {
+      // The json() method steps are to return the result of running
+      // consume body with this and parse JSON from bytes.
+      return specConsumeBody(this, parseJSONFromBytes, instance)
+    },
+
+    async formData () {
+      webidl.brandCheck(this, instance)
+
+      throwIfAborted(this[kState])
+
+      const contentType = this.headers.get('Content-Type')
+
+      // If mimeType’s essence is "multipart/form-data", then:
+      if (/multipart\/form-data/.test(contentType)) {
+        const headers = {}
+        for (const [key, value] of this.headers) headers[key.toLowerCase()] = value
+
+        const responseFormData = new FormData()
+
+        let busboy
+
+        try {
+          busboy = new Busboy({
+            headers,
+            preservePath: true
+          })
+        } catch (err) {
+          throw new DOMException(`${err}`, 'AbortError')
+        }
+
+        busboy.on('field', (name, value) => {
+          responseFormData.append(name, value)
+        })
+        busboy.on('file', (name, value, filename, encoding, mimeType) => {
+          const chunks = []
+
+          if (encoding === 'base64' || encoding.toLowerCase() === 'base64') {
+            let base64chunk = ''
+
+            value.on('data', (chunk) => {
+              base64chunk += chunk.toString().replace(/[\r\n]/gm, '')
+
+              const end = base64chunk.length - base64chunk.length % 4
+              chunks.push(Buffer.from(base64chunk.slice(0, end), 'base64'))
+
+              base64chunk = base64chunk.slice(end)
+            })
+            value.on('end', () => {
+              chunks.push(Buffer.from(base64chunk, 'base64'))
+              responseFormData.append(name, new File(chunks, filename, { type: mimeType }))
+            })
+          } else {
+            value.on('data', (chunk) => {
+              chunks.push(chunk)
+            })
+            value.on('end', () => {
+              responseFormData.append(name, new File(chunks, filename, { type: mimeType }))
+            })
+          }
+        })
+
+        const busboyResolve = new Promise((resolve, reject) => {
+          busboy.on('finish', resolve)
+          busboy.on('error', (err) => reject(new TypeError(err)))
+        })
+
+        if (this.body !== null) for await (const chunk of consumeBody(this[kState].body)) busboy.write(chunk)
+        busboy.end()
+        await busboyResolve
+
+        return responseFormData
+      } else if (/application\/x-www-form-urlencoded/.test(contentType)) {
+        // Otherwise, if mimeType’s essence is "application/x-www-form-urlencoded", then:
+
+        // 1. Let entries be the result of parsing bytes.
+        let entries
+        try {
+          let text = ''
+          // application/x-www-form-urlencoded parser will keep the BOM.
+          // https://url.spec.whatwg.org/#concept-urlencoded-parser
+          // Note that streaming decoder is stateful and cannot be reused
+          const streamingDecoder = new TextDecoder('utf-8', { ignoreBOM: true })
+
+          for await (const chunk of consumeBody(this[kState].body)) {
+            if (!isUint8Array(chunk)) {
+              throw new TypeError('Expected Uint8Array chunk')
+            }
+            text += streamingDecoder.decode(chunk, { stream: true })
+          }
+          text += streamingDecoder.decode()
+          entries = new URLSearchParams(text)
+        } catch (err) {
+          // istanbul ignore next: Unclear when new URLSearchParams can fail on a string.
+          // 2. If entries is failure, then throw a TypeError.
+          throw Object.assign(new TypeError(), { cause: err })
+        }
+
+        // 3. Return a new FormData object whose entries are entries.
+        const formData = new FormData()
+        for (const [name, value] of entries) {
+          formData.append(name, value)
+        }
+        return formData
+      } else {
+        // Wait a tick before checking if the request has been aborted.
+        // Otherwise, a TypeError can be thrown when an AbortError should.
+        await Promise.resolve()
+
+        throwIfAborted(this[kState])
+
+        // Otherwise, throw a TypeError.
+        throw webidl.errors.exception({
+          header: `${instance.name}.formData`,
+          message: 'Could not parse content as FormData.'
+        })
+      }
+    }
+  }
+
+  return methods
+}
+
+function mixinBody (prototype) {
+  Object.assign(prototype.prototype, bodyMixinMethods(prototype))
+}
+
+/**
+ * @see https://fetch.spec.whatwg.org/#concept-body-consume-body
+ * @param {Response|Request} object
+ * @param {(value: unknown) => unknown} convertBytesToJSValue
+ * @param {Response|Request} instance
+ */
+async function specConsumeBody (object, convertBytesToJSValue, instance) {
+  webidl.brandCheck(object, instance)
+
+  throwIfAborted(object[kState])
+
+  // 1. If object is unusable, then return a promise rejected
+  //    with a TypeError.
+  if (bodyUnusable(object[kState].body)) {
+    throw new TypeError('Body is unusable')
+  }
+
+  // 2. Let promise be a new promise.
+  const promise = createDeferredPromise()
+
+  // 3. Let errorSteps given error be to reject promise with error.
+  const errorSteps = (error) => promise.reject(error)
+
+  // 4. Let successSteps given a byte sequence data be to resolve
+  //    promise with the result of running convertBytesToJSValue
+  //    with data. If that threw an exception, then run errorSteps
+  //    with that exception.
+  const successSteps = (data) => {
+    try {
+      promise.resolve(convertBytesToJSValue(data))
+    } catch (e) {
+      errorSteps(e)
+    }
+  }
+
+  // 5. If object’s body is null, then run successSteps with an
+  //    empty byte sequence.
+  if (object[kState].body == null) {
+    successSteps(new Uint8Array())
+    return promise.promise
+  }
+
+  // 6. Otherwise, fully read object’s body given successSteps,
+  //    errorSteps, and object’s relevant global object.
+  await fullyReadBody(object[kState].body, successSteps, errorSteps)
+
+  // 7. Return promise.
+  return promise.promise
+}
+
+// https://fetch.spec.whatwg.org/#body-unusable
+function bodyUnusable (body) {
+  // An object including the Body interface mixin is
+  // said to be unusable if its body is non-null and
+  // its body’s stream is disturbed or locked.
+  return body != null && (body.stream.locked || util.isDisturbed(body.stream))
+}
+
+/**
+ * @see https://encoding.spec.whatwg.org/#utf-8-decode
+ * @param {Buffer} buffer
+ */
+function utf8DecodeBytes (buffer) {
+  if (buffer.length === 0) {
+    return ''
+  }
+
+  // 1. Let buffer be the result of peeking three bytes from
+  //    ioQueue, converted to a byte sequence.
+
+  // 2. If buffer is 0xEF 0xBB 0xBF, then read three
+  //    bytes from ioQueue. (Do nothing with those bytes.)
+  if (buffer[0] === 0xEF && buffer[1] === 0xBB && buffer[2] === 0xBF) {
+    buffer = buffer.subarray(3)
+  }
+
+  // 3. Process a queue with an instance of UTF-8’s
+  //    decoder, ioQueue, output, and "replacement".
+  const output = textDecoder.decode(buffer)
+
+  // 4. Return output.
+  return output
+}
+
+/**
+ * @see https://infra.spec.whatwg.org/#parse-json-bytes-to-a-javascript-value
+ * @param {Uint8Array} bytes
+ */
+function parseJSONFromBytes (bytes) {
+  return JSON.parse(utf8DecodeBytes(bytes))
+}
+
+/**
+ * @see https://fetch.spec.whatwg.org/#concept-body-mime-type
+ * @param {import('./response').Response|import('./request').Request} object
+ */
+function bodyMimeType (object) {
+  const { headersList } = object[kState]
+  const contentType = headersList.get('content-type')
+
+  if (contentType === null) {
+    return 'failure'
+  }
+
+  return parseMIMEType(contentType)
+}
+
+module.exports = {
+  extractBody,
+  safelyExtractBody,
+  cloneBody,
+  mixinBody
+}
diff --git a/lib/fetch/constants.js b/lib/fetch/constants.js
new file mode 100644
index 0000000..218fcbe
--- /dev/null
+++ b/lib/fetch/constants.js
@@ -0,0 +1,151 @@
+'use strict'
+
+const { MessageChannel, receiveMessageOnPort } = require('worker_threads')
+
+const corsSafeListedMethods = ['GET', 'HEAD', 'POST']
+const corsSafeListedMethodsSet = new Set(corsSafeListedMethods)
+
+const nullBodyStatus = [101, 204, 205, 304]
+
+const redirectStatus = [301, 302, 303, 307, 308]
+const redirectStatusSet = new Set(redirectStatus)
+
+// https://fetch.spec.whatwg.org/#block-bad-port
+const badPorts = [
+  '1', '7', '9', '11', '13', '15', '17', '19', '20', '21', '22', '23', '25', '37', '42', '43', '53', '69', '77', '79',
+  '87', '95', '101', '102', '103', '104', '109', '110', '111', '113', '115', '117', '119', '123', '135', '137',
+  '139', '143', '161', '179', '389', '427', '465', '512', '513', '514', '515', '526', '530', '531', '532',
+  '540', '548', '554', '556', '563', '587', '601', '636', '989', '990', '993', '995', '1719', '1720', '1723',
+  '2049', '3659', '4045', '5060', '5061', '6000', '6566', '6665', '6666', '6667', '6668', '6669', '6697',
+  '10080'
+]
+
+const badPortsSet = new Set(badPorts)
+
+// https://w3c.github.io/webappsec-referrer-policy/#referrer-policies
+const referrerPolicy = [
+  '',
+  'no-referrer',
+  'no-referrer-when-downgrade',
+  'same-origin',
+  'origin',
+  'strict-origin',
+  'origin-when-cross-origin',
+  'strict-origin-when-cross-origin',
+  'unsafe-url'
+]
+const referrerPolicySet = new Set(referrerPolicy)
+
+const requestRedirect = ['follow', 'manual', 'error']
+
+const safeMethods = ['GET', 'HEAD', 'OPTIONS', 'TRACE']
+const safeMethodsSet = new Set(safeMethods)
+
+const requestMode = ['navigate', 'same-origin', 'no-cors', 'cors']
+
+const requestCredentials = ['omit', 'same-origin', 'include']
+
+const requestCache = [
+  'default',
+  'no-store',
+  'reload',
+  'no-cache',
+  'force-cache',
+  'only-if-cached'
+]
+
+// https://fetch.spec.whatwg.org/#request-body-header-name
+const requestBodyHeader = [
+  'content-encoding',
+  'content-language',
+  'content-location',
+  'content-type',
+  // See https://github.com/nodejs/undici/issues/2021
+  // 'Content-Length' is a forbidden header name, which is typically
+  // removed in the Headers implementation. However, undici doesn't
+  // filter out headers, so we add it here.
+  'content-length'
+]
+
+// https://fetch.spec.whatwg.org/#enumdef-requestduplex
+const requestDuplex = [
+  'half'
+]
+
+// http://fetch.spec.whatwg.org/#forbidden-method
+const forbiddenMethods = ['CONNECT', 'TRACE', 'TRACK']
+const forbiddenMethodsSet = new Set(forbiddenMethods)
+
+const subresource = [
+  'audio',
+  'audioworklet',
+  'font',
+  'image',
+  'manifest',
+  'paintworklet',
+  'script',
+  'style',
+  'track',
+  'video',
+  'xslt',
+  ''
+]
+const subresourceSet = new Set(subresource)
+
+/** @type {globalThis['DOMException']} */
+const DOMException = globalThis.DOMException ?? (() => {
+  // DOMException was only made a global in Node v17.0.0,
+  // but fetch supports >= v16.8.
+  try {
+    atob('~')
+  } catch (err) {
+    return Object.getPrototypeOf(err).constructor
+  }
+})()
+
+let channel
+
+/** @type {globalThis['structuredClone']} */
+const structuredClone =
+  globalThis.structuredClone ??
+  // https://github.com/nodejs/node/blob/b27ae24dcc4251bad726d9d84baf678d1f707fed/lib/internal/structured_clone.js
+  // structuredClone was added in v17.0.0, but fetch supports v16.8
+  function structuredClone (value, options = undefined) {
+    if (arguments.length === 0) {
+      throw new TypeError('missing argument')
+    }
+
+    if (!channel) {
+      channel = new MessageChannel()
+    }
+    channel.port1.unref()
+    channel.port2.unref()
+    channel.port1.postMessage(value, options?.transfer)
+    return receiveMessageOnPort(channel.port2).message
+  }
+
+module.exports = {
+  DOMException,
+  structuredClone,
+  subresource,
+  forbiddenMethods,
+  requestBodyHeader,
+  referrerPolicy,
+  requestRedirect,
+  requestMode,
+  requestCredentials,
+  requestCache,
+  redirectStatus,
+  corsSafeListedMethods,
+  nullBodyStatus,
+  safeMethods,
+  badPorts,
+  requestDuplex,
+  subresourceSet,
+  badPortsSet,
+  redirectStatusSet,
+  corsSafeListedMethodsSet,
+  safeMethodsSet,
+  forbiddenMethodsSet,
+  referrerPolicySet
+}
diff --git a/lib/fetch/dataURL.js b/lib/fetch/dataURL.js
new file mode 100644
index 0000000..7b6a606
--- /dev/null
+++ b/lib/fetch/dataURL.js
@@ -0,0 +1,627 @@
+const assert = require('assert')
+const { atob } = require('buffer')
+const { isomorphicDecode } = require('./util')
+
+const encoder = new TextEncoder()
+
+/**
+ * @see https://mimesniff.spec.whatwg.org/#http-token-code-point
+ */
+const HTTP_TOKEN_CODEPOINTS = /^[!#$%&'*+-.^_|~A-Za-z0-9]+$/
+const HTTP_WHITESPACE_REGEX = /(\u000A|\u000D|\u0009|\u0020)/ // eslint-disable-line
+/**
+ * @see https://mimesniff.spec.whatwg.org/#http-quoted-string-token-code-point
+ */
+const HTTP_QUOTED_STRING_TOKENS = /[\u0009|\u0020-\u007E|\u0080-\u00FF]/ // eslint-disable-line
+
+// https://fetch.spec.whatwg.org/#data-url-processor
+/** @param {URL} dataURL */
+function dataURLProcessor (dataURL) {
+  // 1. Assert: dataURL’s scheme is "data".
+  assert(dataURL.protocol === 'data:')
+
+  // 2. Let input be the result of running the URL
+  // serializer on dataURL with exclude fragment
+  // set to true.
+  let input = URLSerializer(dataURL, true)
+
+  // 3. Remove the leading "data:" string from input.
+  input = input.slice(5)
+
+  // 4. Let position point at the start of input.
+  const position = { position: 0 }
+
+  // 5. Let mimeType be the result of collecting a
+  // sequence of code points that are not equal
+  // to U+002C (,), given position.
+  let mimeType = collectASequenceOfCodePointsFast(
+    ',',
+    input,
+    position
+  )
+
+  // 6. Strip leading and trailing ASCII whitespace
+  // from mimeType.
+  // Undici implementation note: we need to store the
+  // length because if the mimetype has spaces removed,
+  // the wrong amount will be sliced from the input in
+  // step #9
+  const mimeTypeLength = mimeType.length
+  mimeType = removeASCIIWhitespace(mimeType, true, true)
+
+  // 7. If position is past the end of input, then
+  // return failure
+  if (position.position >= input.length) {
+    return 'failure'
+  }
+
+  // 8. Advance position by 1.
+  position.position++
+
+  // 9. Let encodedBody be the remainder of input.
+  const encodedBody = input.slice(mimeTypeLength + 1)
+
+  // 10. Let body be the percent-decoding of encodedBody.
+  let body = stringPercentDecode(encodedBody)
+
+  // 11. If mimeType ends with U+003B (;), followed by
+  // zero or more U+0020 SPACE, followed by an ASCII
+  // case-insensitive match for "base64", then:
+  if (/;(\u0020){0,}base64$/i.test(mimeType)) {
+    // 1. Let stringBody be the isomorphic decode of body.
+    const stringBody = isomorphicDecode(body)
+
+    // 2. Set body to the forgiving-base64 decode of
+    // stringBody.
+    body = forgivingBase64(stringBody)
+
+    // 3. If body is failure, then return failure.
+    if (body === 'failure') {
+      return 'failure'
+    }
+
+    // 4. Remove the last 6 code points from mimeType.
+    mimeType = mimeType.slice(0, -6)
+
+    // 5. Remove trailing U+0020 SPACE code points from mimeType,
+    // if any.
+    mimeType = mimeType.replace(/(\u0020)+$/, '')
+
+    // 6. Remove the last U+003B (;) code point from mimeType.
+    mimeType = mimeType.slice(0, -1)
+  }
+
+  // 12. If mimeType starts with U+003B (;), then prepend
+  // "text/plain" to mimeType.
+  if (mimeType.startsWith(';')) {
+    mimeType = 'text/plain' + mimeType
+  }
+
+  // 13. Let mimeTypeRecord be the result of parsing
+  // mimeType.
+  let mimeTypeRecord = parseMIMEType(mimeType)
+
+  // 14. If mimeTypeRecord is failure, then set
+  // mimeTypeRecord to text/plain;charset=US-ASCII.
+  if (mimeTypeRecord === 'failure') {
+    mimeTypeRecord = parseMIMEType('text/plain;charset=US-ASCII')
+  }
+
+  // 15. Return a new data: URL struct whose MIME
+  // type is mimeTypeRecord and body is body.
+  // https://fetch.spec.whatwg.org/#data-url-struct
+  return { mimeType: mimeTypeRecord, body }
+}
+
+// https://url.spec.whatwg.org/#concept-url-serializer
+/**
+ * @param {URL} url
+ * @param {boolean} excludeFragment
+ */
+function URLSerializer (url, excludeFragment = false) {
+  if (!excludeFragment) {
+    return url.href
+  }
+
+  const href = url.href
+  const hashLength = url.hash.length
+
+  return hashLength === 0 ? href : href.substring(0, href.length - hashLength)
+}
+
+// https://infra.spec.whatwg.org/#collect-a-sequence-of-code-points
+/**
+ * @param {(char: string) => boolean} condition
+ * @param {string} input
+ * @param {{ position: number }} position
+ */
+function collectASequenceOfCodePoints (condition, input, position) {
+  // 1. Let result be the empty string.
+  let result = ''
+
+  // 2. While position doesn’t point past the end of input and the
+  // code point at position within input meets the condition condition:
+  while (position.position < input.length && condition(input[position.position])) {
+    // 1. Append that code point to the end of result.
+    result += input[position.position]
+
+    // 2. Advance position by 1.
+    position.position++
+  }
+
+  // 3. Return result.
+  return result
+}
+
+/**
+ * A faster collectASequenceOfCodePoints that only works when comparing a single character.
+ * @param {string} char
+ * @param {string} input
+ * @param {{ position: number }} position
+ */
+function collectASequenceOfCodePointsFast (char, input, position) {
+  const idx = input.indexOf(char, position.position)
+  const start = position.position
+
+  if (idx === -1) {
+    position.position = input.length
+    return input.slice(start)
+  }
+
+  position.position = idx
+  return input.slice(start, position.position)
+}
+
+// https://url.spec.whatwg.org/#string-percent-decode
+/** @param {string} input */
+function stringPercentDecode (input) {
+  // 1. Let bytes be the UTF-8 encoding of input.
+  const bytes = encoder.encode(input)
+
+  // 2. Return the percent-decoding of bytes.
+  return percentDecode(bytes)
+}
+
+// https://url.spec.whatwg.org/#percent-decode
+/** @param {Uint8Array} input */
+function percentDecode (input) {
+  // 1. Let output be an empty byte sequence.
+  /** @type {number[]} */
+  const output = []
+
+  // 2. For each byte byte in input:
+  for (let i = 0; i < input.length; i++) {
+    const byte = input[i]
+
+    // 1. If byte is not 0x25 (%), then append byte to output.
+    if (byte !== 0x25) {
+      output.push(byte)
+
+    // 2. Otherwise, if byte is 0x25 (%) and the next two bytes
+    // after byte in input are not in the ranges
+    // 0x30 (0) to 0x39 (9), 0x41 (A) to 0x46 (F),
+    // and 0x61 (a) to 0x66 (f), all inclusive, append byte
+    // to output.
+    } else if (
+      byte === 0x25 &&
+      !/^[0-9A-Fa-f]{2}$/i.test(String.fromCharCode(input[i + 1], input[i + 2]))
+    ) {
+      output.push(0x25)
+
+    // 3. Otherwise:
+    } else {
+      // 1. Let bytePoint be the two bytes after byte in input,
+      // decoded, and then interpreted as hexadecimal number.
+      const nextTwoBytes = String.fromCharCode(input[i + 1], input[i + 2])
+      const bytePoint = Number.parseInt(nextTwoBytes, 16)
+
+      // 2. Append a byte whose value is bytePoint to output.
+      output.push(bytePoint)
+
+      // 3. Skip the next two bytes in input.
+      i += 2
+    }
+  }
+
+  // 3. Return output.
+  return Uint8Array.from(output)
+}
+
+// https://mimesniff.spec.whatwg.org/#parse-a-mime-type
+/** @param {string} input */
+function parseMIMEType (input) {
+  // 1. Remove any leading and trailing HTTP whitespace
+  // from input.
+  input = removeHTTPWhitespace(input, true, true)
+
+  // 2. Let position be a position variable for input,
+  // initially pointing at the start of input.
+  const position = { position: 0 }
+
+  // 3. Let type be the result of collecting a sequence
+  // of code points that are not U+002F (/) from
+  // input, given position.
+  const type = collectASequenceOfCodePointsFast(
+    '/',
+    input,
+    position
+  )
+
+  // 4. If type is the empty string or does not solely
+  // contain HTTP token code points, then return failure.
+  // https://mimesniff.spec.whatwg.org/#http-token-code-point
+  if (type.length === 0 || !HTTP_TOKEN_CODEPOINTS.test(type)) {
+    return 'failure'
+  }
+
+  // 5. If position is past the end of input, then return
+  // failure
+  if (position.position > input.length) {
+    return 'failure'
+  }
+
+  // 6. Advance position by 1. (This skips past U+002F (/).)
+  position.position++
+
+  // 7. Let subtype be the result of collecting a sequence of
+  // code points that are not U+003B (;) from input, given
+  // position.
+  let subtype = collectASequenceOfCodePointsFast(
+    ';',
+    input,
+    position
+  )
+
+  // 8. Remove any trailing HTTP whitespace from subtype.
+  subtype = removeHTTPWhitespace(subtype, false, true)
+
+  // 9. If subtype is the empty string or does not solely
+  // contain HTTP token code points, then return failure.
+  if (subtype.length === 0 || !HTTP_TOKEN_CODEPOINTS.test(subtype)) {
+    return 'failure'
+  }
+
+  const typeLowercase = type.toLowerCase()
+  const subtypeLowercase = subtype.toLowerCase()
+
+  // 10. Let mimeType be a new MIME type record whose type
+  // is type, in ASCII lowercase, and subtype is subtype,
+  // in ASCII lowercase.
+  // https://mimesniff.spec.whatwg.org/#mime-type
+  const mimeType = {
+    type: typeLowercase,
+    subtype: subtypeLowercase,
+    /** @type {Map<string, string>} */
+    parameters: new Map(),
+    // https://mimesniff.spec.whatwg.org/#mime-type-essence
+    essence: `${typeLowercase}/${subtypeLowercase}`
+  }
+
+  // 11. While position is not past the end of input:
+  while (position.position < input.length) {
+    // 1. Advance position by 1. (This skips past U+003B (;).)
+    position.position++
+
+    // 2. Collect a sequence of code points that are HTTP
+    // whitespace from input given position.
+    collectASequenceOfCodePoints(
+      // https://fetch.spec.whatwg.org/#http-whitespace
+      char => HTTP_WHITESPACE_REGEX.test(char),
+      input,
+      position
+    )
+
+    // 3. Let parameterName be the result of collecting a
+    // sequence of code points that are not U+003B (;)
+    // or U+003D (=) from input, given position.
+    let parameterName = collectASequenceOfCodePoints(
+      (char) => char !== ';' && char !== '=',
+      input,
+      position
+    )
+
+    // 4. Set parameterName to parameterName, in ASCII
+    // lowercase.
+    parameterName = parameterName.toLowerCase()
+
+    // 5. If position is not past the end of input, then:
+    if (position.position < input.length) {
+      // 1. If the code point at position within input is
+      // U+003B (;), then continue.
+      if (input[position.position] === ';') {
+        continue
+      }
+
+      // 2. Advance position by 1. (This skips past U+003D (=).)
+      position.position++
+    }
+
+    // 6. If position is past the end of input, then break.
+    if (position.position > input.length) {
+      break
+    }
+
+    // 7. Let parameterValue be null.
+    let parameterValue = null
+
+    // 8. If the code point at position within input is
+    // U+0022 ("), then:
+    if (input[position.position] === '"') {
+      // 1. Set parameterValue to the result of collecting
+      // an HTTP quoted string from input, given position
+      // and the extract-value flag.
+      parameterValue = collectAnHTTPQuotedString(input, position, true)
+
+      // 2. Collect a sequence of code points that are not
+      // U+003B (;) from input, given position.
+      collectASequenceOfCodePointsFast(
+        ';',
+        input,
+        position
+      )
+
+    // 9. Otherwise:
+    } else {
+      // 1. Set parameterValue to the result of collecting
+      // a sequence of code points that are not U+003B (;)
+      // from input, given position.
+      parameterValue = collectASequenceOfCodePointsFast(
+        ';',
+        input,
+        position
+      )
+
+      // 2. Remove any trailing HTTP whitespace from parameterValue.
+      parameterValue = removeHTTPWhitespace(parameterValue, false, true)
+
+      // 3. If parameterValue is the empty string, then continue.
+      if (parameterValue.length === 0) {
+        continue
+      }
+    }
+
+    // 10. If all of the following are true
+    // - parameterName is not the empty string
+    // - parameterName solely contains HTTP token code points
+    // - parameterValue solely contains HTTP quoted-string token code points
+    // - mimeType’s parameters[parameterName] does not exist
+    // then set mimeType’s parameters[parameterName] to parameterValue.
+    if (
+      parameterName.length !== 0 &&
+      HTTP_TOKEN_CODEPOINTS.test(parameterName) &&
+      (parameterValue.length === 0 || HTTP_QUOTED_STRING_TOKENS.test(parameterValue)) &&
+      !mimeType.parameters.has(parameterName)
+    ) {
+      mimeType.parameters.set(parameterName, parameterValue)
+    }
+  }
+
+  // 12. Return mimeType.
+  return mimeType
+}
+
+// https://infra.spec.whatwg.org/#forgiving-base64-decode
+/** @param {string} data */
+function forgivingBase64 (data) {
+  // 1. Remove all ASCII whitespace from data.
+  data = data.replace(/[\u0009\u000A\u000C\u000D\u0020]/g, '')  // eslint-disable-line
+
+  // 2. If data’s code point length divides by 4 leaving
+  // no remainder, then:
+  if (data.length % 4 === 0) {
+    // 1. If data ends with one or two U+003D (=) code points,
+    // then remove them from data.
+    data = data.replace(/=?=$/, '')
+  }
+
+  // 3. If data’s code point length divides by 4 leaving
+  // a remainder of 1, then return failure.
+  if (data.length % 4 === 1) {
+    return 'failure'
+  }
+
+  // 4. If data contains a code point that is not one of
+  //  U+002B (+)
+  //  U+002F (/)
+  //  ASCII alphanumeric
+  // then return failure.
+  if (/[^+/0-9A-Za-z]/.test(data)) {
+    return 'failure'
+  }
+
+  const binary = atob(data)
+  const bytes = new Uint8Array(binary.length)
+
+  for (let byte = 0; byte < binary.length; byte++) {
+    bytes[byte] = binary.charCodeAt(byte)
+  }
+
+  return bytes
+}
+
+// https://fetch.spec.whatwg.org/#collect-an-http-quoted-string
+// tests: https://fetch.spec.whatwg.org/#example-http-quoted-string
+/**
+ * @param {string} input
+ * @param {{ position: number }} position
+ * @param {boolean?} extractValue
+ */
+function collectAnHTTPQuotedString (input, position, extractValue) {
+  // 1. Let positionStart be position.
+  const positionStart = position.position
+
+  // 2. Let value be the empty string.
+  let value = ''
+
+  // 3. Assert: the code point at position within input
+  // is U+0022 (").
+  assert(input[position.position] === '"')
+
+  // 4. Advance position by 1.
+  position.position++
+
+  // 5. While true:
+  while (true) {
+    // 1. Append the result of collecting a sequence of code points
+    // that are not U+0022 (") or U+005C (\) from input, given
+    // position, to value.
+    value += collectASequenceOfCodePoints(
+      (char) => char !== '"' && char !== '\\',
+      input,
+      position
+    )
+
+    // 2. If position is past the end of input, then break.
+    if (position.position >= input.length) {
+      break
+    }
+
+    // 3. Let quoteOrBackslash be the code point at position within
+    // input.
+    const quoteOrBackslash = input[position.position]
+
+    // 4. Advance position by 1.
+    position.position++
+
+    // 5. If quoteOrBackslash is U+005C (\), then:
+    if (quoteOrBackslash === '\\') {
+      // 1. If position is past the end of input, then append
+      // U+005C (\) to value and break.
+      if (position.position >= input.length) {
+        value += '\\'
+        break
+      }
+
+      // 2. Append the code point at position within input to value.
+      value += input[position.position]
+
+      // 3. Advance position by 1.
+      position.position++
+
+    // 6. Otherwise:
+    } else {
+      // 1. Assert: quoteOrBackslash is U+0022 (").
+      assert(quoteOrBackslash === '"')
+
+      // 2. Break.
+      break
+    }
+  }
+
+  // 6. If the extract-value flag is set, then return value.
+  if (extractValue) {
+    return value
+  }
+
+  // 7. Return the code points from positionStart to position,
+  // inclusive, within input.
+  return input.slice(positionStart, position.position)
+}
+
+/**
+ * @see https://mimesniff.spec.whatwg.org/#serialize-a-mime-type
+ */
+function serializeAMimeType (mimeType) {
+  assert(mimeType !== 'failure')
+  const { parameters, essence } = mimeType
+
+  // 1. Let serialization be the concatenation of mimeType’s
+  //    type, U+002F (/), and mimeType’s subtype.
+  let serialization = essence
+
+  // 2. For each name → value of mimeType’s parameters:
+  for (let [name, value] of parameters.entries()) {
+    // 1. Append U+003B (;) to serialization.
+    serialization += ';'
+
+    // 2. Append name to serialization.
+    serialization += name
+
+    // 3. Append U+003D (=) to serialization.
+    serialization += '='
+
+    // 4. If value does not solely contain HTTP token code
+    //    points or value is the empty string, then:
+    if (!HTTP_TOKEN_CODEPOINTS.test(value)) {
+      // 1. Precede each occurence of U+0022 (") or
+      //    U+005C (\) in value with U+005C (\).
+      value = value.replace(/(\\|")/g, '\\$1')
+
+      // 2. Prepend U+0022 (") to value.
+      value = '"' + value
+
+      // 3. Append U+0022 (") to value.
+      value += '"'
+    }
+
+    // 5. Append value to serialization.
+    serialization += value
+  }
+
+  // 3. Return serialization.
+  return serialization
+}
+
+/**
+ * @see https://fetch.spec.whatwg.org/#http-whitespace
+ * @param {string} char
+ */
+function isHTTPWhiteSpace (char) {
+  return char === '\r' || char === '\n' || char === '\t' || char === ' '
+}
+
+/**
+ * @see https://fetch.spec.whatwg.org/#http-whitespace
+ * @param {string} str
+ */
+function removeHTTPWhitespace (str, leading = true, trailing = true) {
+  let lead = 0
+  let trail = str.length - 1
+
+  if (leading) {
+    for (; lead < str.length && isHTTPWhiteSpace(str[lead]); lead++);
+  }
+
+  if (trailing) {
+    for (; trail > 0 && isHTTPWhiteSpace(str[trail]); trail--);
+  }
+
+  return str.slice(lead, trail + 1)
+}
+
+/**
+ * @see https://infra.spec.whatwg.org/#ascii-whitespace
+ * @param {string} char
+ */
+function isASCIIWhitespace (char) {
+  return char === '\r' || char === '\n' || char === '\t' || char === '\f' || char === ' '
+}
+
+/**
+ * @see https://infra.spec.whatwg.org/#strip-leading-and-trailing-ascii-whitespace
+ */
+function removeASCIIWhitespace (str, leading = true, trailing = true) {
+  let lead = 0
+  let trail = str.length - 1
+
+  if (leading) {
+    for (; lead < str.length && isASCIIWhitespace(str[lead]); lead++);
+  }
+
+  if (trailing) {
+    for (; trail > 0 && isASCIIWhitespace(str[trail]); trail--);
+  }
+
+  return str.slice(lead, trail + 1)
+}
+
+module.exports = {
+  dataURLProcessor,
+  URLSerializer,
+  collectASequenceOfCodePoints,
+  collectASequenceOfCodePointsFast,
+  stringPercentDecode,
+  parseMIMEType,
+  collectAnHTTPQuotedString,
+  serializeAMimeType
+}
diff --git a/lib/fetch/file.js b/lib/fetch/file.js
new file mode 100644
index 0000000..3133d25
--- /dev/null
+++ b/lib/fetch/file.js
@@ -0,0 +1,344 @@
+'use strict'
+
+const { Blob, File: NativeFile } = require('buffer')
+const { types } = require('util')
+const { kState } = require('./symbols')
+const { isBlobLike } = require('./util')
+const { webidl } = require('./webidl')
+const { parseMIMEType, serializeAMimeType } = require('./dataURL')
+const { kEnumerableProperty } = require('../core/util')
+const encoder = new TextEncoder()
+
+class File extends Blob {
+  constructor (fileBits, fileName, options = {}) {
+    // The File constructor is invoked with two or three parameters, depending
+    // on whether the optional dictionary parameter is used. When the File()
+    // constructor is invoked, user agents must run the following steps:
+    webidl.argumentLengthCheck(arguments, 2, { header: 'File constructor' })
+
+    fileBits = webidl.converters['sequence<BlobPart>'](fileBits)
+    fileName = webidl.converters.USVString(fileName)
+    options = webidl.converters.FilePropertyBag(options)
+
+    // 1. Let bytes be the result of processing blob parts given fileBits and
+    // options.
+    // Note: Blob handles this for us
+
+    // 2. Let n be the fileName argument to the constructor.
+    const n = fileName
+
+    // 3. Process FilePropertyBag dictionary argument by running the following
+    // substeps:
+
+    //    1. If the type member is provided and is not the empty string, let t
+    //    be set to the type dictionary member. If t contains any characters
+    //    outside the range U+0020 to U+007E, then set t to the empty string
+    //    and return from these substeps.
+    //    2. Convert every character in t to ASCII lowercase.
+    let t = options.type
+    let d
+
+    // eslint-disable-next-line no-labels
+    substep: {
+      if (t) {
+        t = parseMIMEType(t)
+
+        if (t === 'failure') {
+          t = ''
+          // eslint-disable-next-line no-labels
+          break substep
+        }
+
+        t = serializeAMimeType(t).toLowerCase()
+      }
+
+      //    3. If the lastModified member is provided, let d be set to the
+      //    lastModified dictionary member. If it is not provided, set d to the
+      //    current date and time represented as the number of milliseconds since
+      //    the Unix Epoch (which is the equivalent of Date.now() [ECMA-262]).
+      d = options.lastModified
+    }
+
+    // 4. Return a new File object F such that:
+    // F refers to the bytes byte sequence.
+    // F.size is set to the number of total bytes in bytes.
+    // F.name is set to n.
+    // F.type is set to t.
+    // F.lastModified is set to d.
+
+    super(processBlobParts(fileBits, options), { type: t })
+    this[kState] = {
+      name: n,
+      lastModified: d,
+      type: t
+    }
+  }
+
+  get name () {
+    webidl.brandCheck(this, File)
+
+    return this[kState].name
+  }
+
+  get lastModified () {
+    webidl.brandCheck(this, File)
+
+    return this[kState].lastModified
+  }
+
+  get type () {
+    webidl.brandCheck(this, File)
+
+    return this[kState].type
+  }
+}
+
+class FileLike {
+  constructor (blobLike, fileName, options = {}) {
+    // TODO: argument idl type check
+
+    // The File constructor is invoked with two or three parameters, depending
+    // on whether the optional dictionary parameter is used. When the File()
+    // constructor is invoked, user agents must run the following steps:
+
+    // 1. Let bytes be the result of processing blob parts given fileBits and
+    // options.
+
+    // 2. Let n be the fileName argument to the constructor.
+    const n = fileName
+
+    // 3. Process FilePropertyBag dictionary argument by running the following
+    // substeps:
+
+    //    1. If the type member is provided and is not the empty string, let t
+    //    be set to the type dictionary member. If t contains any characters
+    //    outside the range U+0020 to U+007E, then set t to the empty string
+    //    and return from these substeps.
+    //    TODO
+    const t = options.type
+
+    //    2. Convert every character in t to ASCII lowercase.
+    //    TODO
+
+    //    3. If the lastModified member is provided, let d be set to the
+    //    lastModified dictionary member. If it is not provided, set d to the
+    //    current date and time represented as the number of milliseconds since
+    //    the Unix Epoch (which is the equivalent of Date.now() [ECMA-262]).
+    const d = options.lastModified ?? Date.now()
+
+    // 4. Return a new File object F such that:
+    // F refers to the bytes byte sequence.
+    // F.size is set to the number of total bytes in bytes.
+    // F.name is set to n.
+    // F.type is set to t.
+    // F.lastModified is set to d.
+
+    this[kState] = {
+      blobLike,
+      name: n,
+      type: t,
+      lastModified: d
+    }
+  }
+
+  stream (...args) {
+    webidl.brandCheck(this, FileLike)
+
+    return this[kState].blobLike.stream(...args)
+  }
+
+  arrayBuffer (...args) {
+    webidl.brandCheck(this, FileLike)
+
+    return this[kState].blobLike.arrayBuffer(...args)
+  }
+
+  slice (...args) {
+    webidl.brandCheck(this, FileLike)
+
+    return this[kState].blobLike.slice(...args)
+  }
+
+  text (...args) {
+    webidl.brandCheck(this, FileLike)
+
+    return this[kState].blobLike.text(...args)
+  }
+
+  get size () {
+    webidl.brandCheck(this, FileLike)
+
+    return this[kState].blobLike.size
+  }
+
+  get type () {
+    webidl.brandCheck(this, FileLike)
+
+    return this[kState].blobLike.type
+  }
+
+  get name () {
+    webidl.brandCheck(this, FileLike)
+
+    return this[kState].name
+  }
+
+  get lastModified () {
+    webidl.brandCheck(this, FileLike)
+
+    return this[kState].lastModified
+  }
+
+  get [Symbol.toStringTag] () {
+    return 'File'
+  }
+}
+
+Object.defineProperties(File.prototype, {
+  [Symbol.toStringTag]: {
+    value: 'File',
+    configurable: true
+  },
+  name: kEnumerableProperty,
+  lastModified: kEnumerableProperty
+})
+
+webidl.converters.Blob = webidl.interfaceConverter(Blob)
+
+webidl.converters.BlobPart = function (V, opts) {
+  if (webidl.util.Type(V) === 'Object') {
+    if (isBlobLike(V)) {
+      return webidl.converters.Blob(V, { strict: false })
+    }
+
+    if (
+      ArrayBuffer.isView(V) ||
+      types.isAnyArrayBuffer(V)
+    ) {
+      return webidl.converters.BufferSource(V, opts)
+    }
+  }
+
+  return webidl.converters.USVString(V, opts)
+}
+
+webidl.converters['sequence<BlobPart>'] = webidl.sequenceConverter(
+  webidl.converters.BlobPart
+)
+
+// https://www.w3.org/TR/FileAPI/#dfn-FilePropertyBag
+webidl.converters.FilePropertyBag = webidl.dictionaryConverter([
+  {
+    key: 'lastModified',
+    converter: webidl.converters['long long'],
+    get defaultValue () {
+      return Date.now()
+    }
+  },
+  {
+    key: 'type',
+    converter: webidl.converters.DOMString,
+    defaultValue: ''
+  },
+  {
+    key: 'endings',
+    converter: (value) => {
+      value = webidl.converters.DOMString(value)
+      value = value.toLowerCase()
+
+      if (value !== 'native') {
+        value = 'transparent'
+      }
+
+      return value
+    },
+    defaultValue: 'transparent'
+  }
+])
+
+/**
+ * @see https://www.w3.org/TR/FileAPI/#process-blob-parts
+ * @param {(NodeJS.TypedArray|Blob|string)[]} parts
+ * @param {{ type: string, endings: string }} options
+ */
+function processBlobParts (parts, options) {
+  // 1. Let bytes be an empty sequence of bytes.
+  /** @type {NodeJS.TypedArray[]} */
+  const bytes = []
+
+  // 2. For each element in parts:
+  for (const element of parts) {
+    // 1. If element is a USVString, run the following substeps:
+    if (typeof element === 'string') {
+      // 1. Let s be element.
+      let s = element
+
+      // 2. If the endings member of options is "native", set s
+      //    to the result of converting line endings to native
+      //    of element.
+      if (options.endings === 'native') {
+        s = convertLineEndingsNative(s)
+      }
+
+      // 3. Append the result of UTF-8 encoding s to bytes.
+      bytes.push(encoder.encode(s))
+    } else if (
+      types.isAnyArrayBuffer(element) ||
+      types.isTypedArray(element)
+    ) {
+      // 2. If element is a BufferSource, get a copy of the
+      //    bytes held by the buffer source, and append those
+      //    bytes to bytes.
+      if (!element.buffer) { // ArrayBuffer
+        bytes.push(new Uint8Array(element))
+      } else {
+        bytes.push(
+          new Uint8Array(element.buffer, element.byteOffset, element.byteLength)
+        )
+      }
+    } else if (isBlobLike(element)) {
+      // 3. If element is a Blob, append the bytes it represents
+      //    to bytes.
+      bytes.push(element)
+    }
+  }
+
+  // 3. Return bytes.
+  return bytes
+}
+
+/**
+ * @see https://www.w3.org/TR/FileAPI/#convert-line-endings-to-native
+ * @param {string} s
+ */
+function convertLineEndingsNative (s) {
+  // 1. Let native line ending be be the code point U+000A LF.
+  let nativeLineEnding = '\n'
+
+  // 2. If the underlying platform’s conventions are to
+  //    represent newlines as a carriage return and line feed
+  //    sequence, set native line ending to the code point
+  //    U+000D CR followed by the code point U+000A LF.
+  if (process.platform === 'win32') {
+    nativeLineEnding = '\r\n'
+  }
+
+  return s.replace(/\r?\n/g, nativeLineEnding)
+}
+
+// If this function is moved to ./util.js, some tools (such as
+// rollup) will warn about circular dependencies. See:
+// https://github.com/nodejs/undici/issues/1629
+function isFileLike (object) {
+  return (
+    (NativeFile && object instanceof NativeFile) ||
+    object instanceof File || (
+      object &&
+      (typeof object.stream === 'function' ||
+      typeof object.arrayBuffer === 'function') &&
+      object[Symbol.toStringTag] === 'File'
+    )
+  )
+}
+
+module.exports = { File, FileLike, isFileLike }
diff --git a/lib/fetch/formdata.js b/lib/fetch/formdata.js
new file mode 100644
index 0000000..5975e26
--- /dev/null
+++ b/lib/fetch/formdata.js
@@ -0,0 +1,265 @@
+'use strict'
+
+const { isBlobLike, toUSVString, makeIterator } = require('./util')
+const { kState } = require('./symbols')
+const { File: UndiciFile, FileLike, isFileLike } = require('./file')
+const { webidl } = require('./webidl')
+const { Blob, File: NativeFile } = require('buffer')
+
+/** @type {globalThis['File']} */
+const File = NativeFile ?? UndiciFile
+
+// https://xhr.spec.whatwg.org/#formdata
+class FormData {
+  constructor (form) {
+    if (form !== undefined) {
+      throw webidl.errors.conversionFailed({
+        prefix: 'FormData constructor',
+        argument: 'Argument 1',
+        types: ['undefined']
+      })
+    }
+
+    this[kState] = []
+  }
+
+  append (name, value, filename = undefined) {
+    webidl.brandCheck(this, FormData)
+
+    webidl.argumentLengthCheck(arguments, 2, { header: 'FormData.append' })
+
+    if (arguments.length === 3 && !isBlobLike(value)) {
+      throw new TypeError(
+        "Failed to execute 'append' on 'FormData': parameter 2 is not of type 'Blob'"
+      )
+    }
+
+    // 1. Let value be value if given; otherwise blobValue.
+
+    name = webidl.converters.USVString(name)
+    value = isBlobLike(value)
+      ? webidl.converters.Blob(value, { strict: false })
+      : webidl.converters.USVString(value)
+    filename = arguments.length === 3
+      ? webidl.converters.USVString(filename)
+      : undefined
+
+    // 2. Let entry be the result of creating an entry with
+    // name, value, and filename if given.
+    const entry = makeEntry(name, value, filename)
+
+    // 3. Append entry to this’s entry list.
+    this[kState].push(entry)
+  }
+
+  delete (name) {
+    webidl.brandCheck(this, FormData)
+
+    webidl.argumentLengthCheck(arguments, 1, { header: 'FormData.delete' })
+
+    name = webidl.converters.USVString(name)
+
+    // The delete(name) method steps are to remove all entries whose name
+    // is name from this’s entry list.
+    this[kState] = this[kState].filter(entry => entry.name !== name)
+  }
+
+  get (name) {
+    webidl.brandCheck(this, FormData)
+
+    webidl.argumentLengthCheck(arguments, 1, { header: 'FormData.get' })
+
+    name = webidl.converters.USVString(name)
+
+    // 1. If there is no entry whose name is name in this’s entry list,
+    // then return null.
+    const idx = this[kState].findIndex((entry) => entry.name === name)
+    if (idx === -1) {
+      return null
+    }
+
+    // 2. Return the value of the first entry whose name is name from
+    // this’s entry list.
+    return this[kState][idx].value
+  }
+
+  getAll (name) {
+    webidl.brandCheck(this, FormData)
+
+    webidl.argumentLengthCheck(arguments, 1, { header: 'FormData.getAll' })
+
+    name = webidl.converters.USVString(name)
+
+    // 1. If there is no entry whose name is name in this’s entry list,
+    // then return the empty list.
+    // 2. Return the values of all entries whose name is name, in order,
+    // from this’s entry list.
+    return this[kState]
+      .filter((entry) => entry.name === name)
+      .map((entry) => entry.value)
+  }
+
+  has (name) {
+    webidl.brandCheck(this, FormData)
+
+    webidl.argumentLengthCheck(arguments, 1, { header: 'FormData.has' })
+
+    name = webidl.converters.USVString(name)
+
+    // The has(name) method steps are to return true if there is an entry
+    // whose name is name in this’s entry list; otherwise false.
+    return this[kState].findIndex((entry) => entry.name === name) !== -1
+  }
+
+  set (name, value, filename = undefined) {
+    webidl.brandCheck(this, FormData)
+
+    webidl.argumentLengthCheck(arguments, 2, { header: 'FormData.set' })
+
+    if (arguments.length === 3 && !isBlobLike(value)) {
+      throw new TypeError(
+        "Failed to execute 'set' on 'FormData': parameter 2 is not of type 'Blob'"
+      )
+    }
+
+    // The set(name, value) and set(name, blobValue, filename) method steps
+    // are:
+
+    // 1. Let value be value if given; otherwise blobValue.
+
+    name = webidl.converters.USVString(name)
+    value = isBlobLike(value)
+      ? webidl.converters.Blob(value, { strict: false })
+      : webidl.converters.USVString(value)
+    filename = arguments.length === 3
+      ? toUSVString(filename)
+      : undefined
+
+    // 2. Let entry be the result of creating an entry with name, value, and
+    // filename if given.
+    const entry = makeEntry(name, value, filename)
+
+    // 3. If there are entries in this’s entry list whose name is name, then
+    // replace the first such entry with entry and remove the others.
+    const idx = this[kState].findIndex((entry) => entry.name === name)
+    if (idx !== -1) {
+      this[kState] = [
+        ...this[kState].slice(0, idx),
+        entry,
+        ...this[kState].slice(idx + 1).filter((entry) => entry.name !== name)
+      ]
+    } else {
+      // 4. Otherwise, append entry to this’s entry list.
+      this[kState].push(entry)
+    }
+  }
+
+  entries () {
+    webidl.brandCheck(this, FormData)
+
+    return makeIterator(
+      () => this[kState].map(pair => [pair.name, pair.value]),
+      'FormData',
+      'key+value'
+    )
+  }
+
+  keys () {
+    webidl.brandCheck(this, FormData)
+
+    return makeIterator(
+      () => this[kState].map(pair => [pair.name, pair.value]),
+      'FormData',
+      'key'
+    )
+  }
+
+  values () {
+    webidl.brandCheck(this, FormData)
+
+    return makeIterator(
+      () => this[kState].map(pair => [pair.name, pair.value]),
+      'FormData',
+      'value'
+    )
+  }
+
+  /**
+   * @param {(value: string, key: string, self: FormData) => void} callbackFn
+   * @param {unknown} thisArg
+   */
+  forEach (callbackFn, thisArg = globalThis) {
+    webidl.brandCheck(this, FormData)
+
+    webidl.argumentLengthCheck(arguments, 1, { header: 'FormData.forEach' })
+
+    if (typeof callbackFn !== 'function') {
+      throw new TypeError(
+        "Failed to execute 'forEach' on 'FormData': parameter 1 is not of type 'Function'."
+      )
+    }
+
+    for (const [key, value] of this) {
+      callbackFn.apply(thisArg, [value, key, this])
+    }
+  }
+}
+
+FormData.prototype[Symbol.iterator] = FormData.prototype.entries
+
+Object.defineProperties(FormData.prototype, {
+  [Symbol.toStringTag]: {
+    value: 'FormData',
+    configurable: true
+  }
+})
+
+/**
+ * @see https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#create-an-entry
+ * @param {string} name
+ * @param {string|Blob} value
+ * @param {?string} filename
+ * @returns
+ */
+function makeEntry (name, value, filename) {
+  // 1. Set name to the result of converting name into a scalar value string.
+  // "To convert a string into a scalar value string, replace any surrogates
+  //  with U+FFFD."
+  // see: https://nodejs.org/dist/latest-v18.x/docs/api/buffer.html#buftostringencoding-start-end
+  name = Buffer.from(name).toString('utf8')
+
+  // 2. If value is a string, then set value to the result of converting
+  //    value into a scalar value string.
+  if (typeof value === 'string') {
+    value = Buffer.from(value).toString('utf8')
+  } else {
+    // 3. Otherwise:
+
+    // 1. If value is not a File object, then set value to a new File object,
+    //    representing the same bytes, whose name attribute value is "blob"
+    if (!isFileLike(value)) {
+      value = value instanceof Blob
+        ? new File([value], 'blob', { type: value.type })
+        : new FileLike(value, 'blob', { type: value.type })
+    }
+
+    // 2. If filename is given, then set value to a new File object,
+    //    representing the same bytes, whose name attribute is filename.
+    if (filename !== undefined) {
+      /** @type {FilePropertyBag} */
+      const options = {
+        type: value.type,
+        lastModified: value.lastModified
+      }
+
+      value = (NativeFile && value instanceof NativeFile) || value instanceof UndiciFile
+        ? new File([value], filename, options)
+        : new FileLike(value, filename, options)
+    }
+  }
+
+  // 4. Return an entry whose name is name and whose value is value.
+  return { name, value }
+}
+
+module.exports = { FormData }
diff --git a/lib/fetch/global.js b/lib/fetch/global.js
new file mode 100644
index 0000000..1df6f12
--- /dev/null
+++ b/lib/fetch/global.js
@@ -0,0 +1,40 @@
+'use strict'
+
+// In case of breaking changes, increase the version
+// number to avoid conflicts.
+const globalOrigin = Symbol.for('undici.globalOrigin.1')
+
+function getGlobalOrigin () {
+  return globalThis[globalOrigin]
+}
+
+function setGlobalOrigin (newOrigin) {
+  if (newOrigin === undefined) {
+    Object.defineProperty(globalThis, globalOrigin, {
+      value: undefined,
+      writable: true,
+      enumerable: false,
+      configurable: false
+    })
+
+    return
+  }
+
+  const parsedURL = new URL(newOrigin)
+
+  if (parsedURL.protocol !== 'http:' && parsedURL.protocol !== 'https:') {
+    throw new TypeError(`Only http & https urls are allowed, received ${parsedURL.protocol}`)
+  }
+
+  Object.defineProperty(globalThis, globalOrigin, {
+    value: parsedURL,
+    writable: true,
+    enumerable: false,
+    configurable: false
+  })
+}
+
+module.exports = {
+  getGlobalOrigin,
+  setGlobalOrigin
+}
diff --git a/lib/fetch/headers.js b/lib/fetch/headers.js
new file mode 100644
index 0000000..2f1c0be
--- /dev/null
+++ b/lib/fetch/headers.js
@@ -0,0 +1,589 @@
+// https://github.com/Ethan-Arrowood/undici-fetch
+
+'use strict'
+
+const { kHeadersList, kConstruct } = require('../core/symbols')
+const { kGuard } = require('./symbols')
+const { kEnumerableProperty } = require('../core/util')
+const {
+  makeIterator,
+  isValidHeaderName,
+  isValidHeaderValue
+} = require('./util')
+const { webidl } = require('./webidl')
+const assert = require('assert')
+
+const kHeadersMap = Symbol('headers map')
+const kHeadersSortedMap = Symbol('headers map sorted')
+
+/**
+ * @param {number} code
+ */
+function isHTTPWhiteSpaceCharCode (code) {
+  return code === 0x00a || code === 0x00d || code === 0x009 || code === 0x020
+}
+
+/**
+ * @see https://fetch.spec.whatwg.org/#concept-header-value-normalize
+ * @param {string} potentialValue
+ */
+function headerValueNormalize (potentialValue) {
+  //  To normalize a byte sequence potentialValue, remove
+  //  any leading and trailing HTTP whitespace bytes from
+  //  potentialValue.
+  let i = 0; let j = potentialValue.length
+
+  while (j > i && isHTTPWhiteSpaceCharCode(potentialValue.charCodeAt(j - 1))) --j
+  while (j > i && isHTTPWhiteSpaceCharCode(potentialValue.charCodeAt(i))) ++i
+
+  return i === 0 && j === potentialValue.length ? potentialValue : potentialValue.substring(i, j)
+}
+
+function fill (headers, object) {
+  // To fill a Headers object headers with a given object object, run these steps:
+
+  // 1. If object is a sequence, then for each header in object:
+  // Note: webidl conversion to array has already been done.
+  if (Array.isArray(object)) {
+    for (let i = 0; i < object.length; ++i) {
+      const header = object[i]
+      // 1. If header does not contain exactly two items, then throw a TypeError.
+      if (header.length !== 2) {
+        throw webidl.errors.exception({
+          header: 'Headers constructor',
+          message: `expected name/value pair to be length 2, found ${header.length}.`
+        })
+      }
+
+      // 2. Append (header’s first item, header’s second item) to headers.
+      appendHeader(headers, header[0], header[1])
+    }
+  } else if (typeof object === 'object' && object !== null) {
+    // Note: null should throw
+
+    // 2. Otherwise, object is a record, then for each key → value in object,
+    //    append (key, value) to headers
+    const keys = Object.keys(object)
+    for (let i = 0; i < keys.length; ++i) {
+      appendHeader(headers, keys[i], object[keys[i]])
+    }
+  } else {
+    throw webidl.errors.conversionFailed({
+      prefix: 'Headers constructor',
+      argument: 'Argument 1',
+      types: ['sequence<sequence<ByteString>>', 'record<ByteString, ByteString>']
+    })
+  }
+}
+
+/**
+ * @see https://fetch.spec.whatwg.org/#concept-headers-append
+ */
+function appendHeader (headers, name, value) {
+  // 1. Normalize value.
+  value = headerValueNormalize(value)
+
+  // 2. If name is not a header name or value is not a
+  //    header value, then throw a TypeError.
+  if (!isValidHeaderName(name)) {
+    throw webidl.errors.invalidArgument({
+      prefix: 'Headers.append',
+      value: name,
+      type: 'header name'
+    })
+  } else if (!isValidHeaderValue(value)) {
+    throw webidl.errors.invalidArgument({
+      prefix: 'Headers.append',
+      value,
+      type: 'header value'
+    })
+  }
+
+  // 3. If headers’s guard is "immutable", then throw a TypeError.
+  // 4. Otherwise, if headers’s guard is "request" and name is a
+  //    forbidden header name, return.
+  // Note: undici does not implement forbidden header names
+  if (headers[kGuard] === 'immutable') {
+    throw new TypeError('immutable')
+  } else if (headers[kGuard] === 'request-no-cors') {
+    // 5. Otherwise, if headers’s guard is "request-no-cors":
+    // TODO
+  }
+
+  // 6. Otherwise, if headers’s guard is "response" and name is a
+  //    forbidden response-header name, return.
+
+  // 7. Append (name, value) to headers’s header list.
+  return headers[kHeadersList].append(name, value)
+
+  // 8. If headers’s guard is "request-no-cors", then remove
+  //    privileged no-CORS request headers from headers
+}
+
+class HeadersList {
+  /** @type {[string, string][]|null} */
+  cookies = null
+
+  constructor (init) {
+    if (init instanceof HeadersList) {
+      this[kHeadersMap] = new Map(init[kHeadersMap])
+      this[kHeadersSortedMap] = init[kHeadersSortedMap]
+      this.cookies = init.cookies === null ? null : [...init.cookies]
+    } else {
+      this[kHeadersMap] = new Map(init)
+      this[kHeadersSortedMap] = null
+    }
+  }
+
+  // https://fetch.spec.whatwg.org/#header-list-contains
+  contains (name) {
+    // A header list list contains a header name name if list
+    // contains a header whose name is a byte-case-insensitive
+    // match for name.
+    name = name.toLowerCase()
+
+    return this[kHeadersMap].has(name)
+  }
+
+  clear () {
+    this[kHeadersMap].clear()
+    this[kHeadersSortedMap] = null
+    this.cookies = null
+  }
+
+  // https://fetch.spec.whatwg.org/#concept-header-list-append
+  append (name, value) {
+    this[kHeadersSortedMap] = null
+
+    // 1. If list contains name, then set name to the first such
+    //    header’s name.
+    const lowercaseName = name.toLowerCase()
+    const exists = this[kHeadersMap].get(lowercaseName)
+
+    // 2. Append (name, value) to list.
+    if (exists) {
+      const delimiter = lowercaseName === 'cookie' ? '; ' : ', '
+      this[kHeadersMap].set(lowercaseName, {
+        name: exists.name,
+        value: `${exists.value}${delimiter}${value}`
+      })
+    } else {
+      this[kHeadersMap].set(lowercaseName, { name, value })
+    }
+
+    if (lowercaseName === 'set-cookie') {
+      this.cookies ??= []
+      this.cookies.push(value)
+    }
+  }
+
+  // https://fetch.spec.whatwg.org/#concept-header-list-set
+  set (name, value) {
+    this[kHeadersSortedMap] = null
+    const lowercaseName = name.toLowerCase()
+
+    if (lowercaseName === 'set-cookie') {
+      this.cookies = [value]
+    }
+
+    // 1. If list contains name, then set the value of
+    //    the first such header to value and remove the
+    //    others.
+    // 2. Otherwise, append header (name, value) to list.
+    this[kHeadersMap].set(lowercaseName, { name, value })
+  }
+
+  // https://fetch.spec.whatwg.org/#concept-header-list-delete
+  delete (name) {
+    this[kHeadersSortedMap] = null
+
+    name = name.toLowerCase()
+
+    if (name === 'set-cookie') {
+      this.cookies = null
+    }
+
+    this[kHeadersMap].delete(name)
+  }
+
+  // https://fetch.spec.whatwg.org/#concept-header-list-get
+  get (name) {
+    const value = this[kHeadersMap].get(name.toLowerCase())
+
+    // 1. If list does not contain name, then return null.
+    // 2. Return the values of all headers in list whose name
+    //    is a byte-case-insensitive match for name,
+    //    separated from each other by 0x2C 0x20, in order.
+    return value === undefined ? null : value.value
+  }
+
+  * [Symbol.iterator] () {
+    // use the lowercased name
+    for (const [name, { value }] of this[kHeadersMap]) {
+      yield [name, value]
+    }
+  }
+
+  get entries () {
+    const headers = {}
+
+    if (this[kHeadersMap].size) {
+      for (const { name, value } of this[kHeadersMap].values()) {
+        headers[name] = value
+      }
+    }
+
+    return headers
+  }
+}
+
+// https://fetch.spec.whatwg.org/#headers-class
+class Headers {
+  constructor (init = undefined) {
+    if (init === kConstruct) {
+      return
+    }
+    this[kHeadersList] = new HeadersList()
+
+    // The new Headers(init) constructor steps are:
+
+    // 1. Set this’s guard to "none".
+    this[kGuard] = 'none'
+
+    // 2. If init is given, then fill this with init.
+    if (init !== undefined) {
+      init = webidl.converters.HeadersInit(init)
+      fill(this, init)
+    }
+  }
+
+  // https://fetch.spec.whatwg.org/#dom-headers-append
+  append (name, value) {
+    webidl.brandCheck(this, Headers)
+
+    webidl.argumentLengthCheck(arguments, 2, { header: 'Headers.append' })
+
+    name = webidl.converters.ByteString(name)
+    value = webidl.converters.ByteString(value)
+
+    return appendHeader(this, name, value)
+  }
+
+  // https://fetch.spec.whatwg.org/#dom-headers-delete
+  delete (name) {
+    webidl.brandCheck(this, Headers)
+
+    webidl.argumentLengthCheck(arguments, 1, { header: 'Headers.delete' })
+
+    name = webidl.converters.ByteString(name)
+
+    // 1. If name is not a header name, then throw a TypeError.
+    if (!isValidHeaderName(name)) {
+      throw webidl.errors.invalidArgument({
+        prefix: 'Headers.delete',
+        value: name,
+        type: 'header name'
+      })
+    }
+
+    // 2. If this’s guard is "immutable", then throw a TypeError.
+    // 3. Otherwise, if this’s guard is "request" and name is a
+    //    forbidden header name, return.
+    // 4. Otherwise, if this’s guard is "request-no-cors", name
+    //    is not a no-CORS-safelisted request-header name, and
+    //    name is not a privileged no-CORS request-header name,
+    //    return.
+    // 5. Otherwise, if this’s guard is "response" and name is
+    //    a forbidden response-header name, return.
+    // Note: undici does not implement forbidden header names
+    if (this[kGuard] === 'immutable') {
+      throw new TypeError('immutable')
+    } else if (this[kGuard] === 'request-no-cors') {
+      // TODO
+    }
+
+    // 6. If this’s header list does not contain name, then
+    //    return.
+    if (!this[kHeadersList].contains(name)) {
+      return
+    }
+
+    // 7. Delete name from this’s header list.
+    // 8. If this’s guard is "request-no-cors", then remove
+    //    privileged no-CORS request headers from this.
+    this[kHeadersList].delete(name)
+  }
+
+  // https://fetch.spec.whatwg.org/#dom-headers-get
+  get (name) {
+    webidl.brandCheck(this, Headers)
+
+    webidl.argumentLengthCheck(arguments, 1, { header: 'Headers.get' })
+
+    name = webidl.converters.ByteString(name)
+
+    // 1. If name is not a header name, then throw a TypeError.
+    if (!isValidHeaderName(name)) {
+      throw webidl.errors.invalidArgument({
+        prefix: 'Headers.get',
+        value: name,
+        type: 'header name'
+      })
+    }
+
+    // 2. Return the result of getting name from this’s header
+    //    list.
+    return this[kHeadersList].get(name)
+  }
+
+  // https://fetch.spec.whatwg.org/#dom-headers-has
+  has (name) {
+    webidl.brandCheck(this, Headers)
+
+    webidl.argumentLengthCheck(arguments, 1, { header: 'Headers.has' })
+
+    name = webidl.converters.ByteString(name)
+
+    // 1. If name is not a header name, then throw a TypeError.
+    if (!isValidHeaderName(name)) {
+      throw webidl.errors.invalidArgument({
+        prefix: 'Headers.has',
+        value: name,
+        type: 'header name'
+      })
+    }
+
+    // 2. Return true if this’s header list contains name;
+    //    otherwise false.
+    return this[kHeadersList].contains(name)
+  }
+
+  // https://fetch.spec.whatwg.org/#dom-headers-set
+  set (name, value) {
+    webidl.brandCheck(this, Headers)
+
+    webidl.argumentLengthCheck(arguments, 2, { header: 'Headers.set' })
+
+    name = webidl.converters.ByteString(name)
+    value = webidl.converters.ByteString(value)
+
+    // 1. Normalize value.
+    value = headerValueNormalize(value)
+
+    // 2. If name is not a header name or value is not a
+    //    header value, then throw a TypeError.
+    if (!isValidHeaderName(name)) {
+      throw webidl.errors.invalidArgument({
+        prefix: 'Headers.set',
+        value: name,
+        type: 'header name'
+      })
+    } else if (!isValidHeaderValue(value)) {
+      throw webidl.errors.invalidArgument({
+        prefix: 'Headers.set',
+        value,
+        type: 'header value'
+      })
+    }
+
+    // 3. If this’s guard is "immutable", then throw a TypeError.
+    // 4. Otherwise, if this’s guard is "request" and name is a
+    //    forbidden header name, return.
+    // 5. Otherwise, if this’s guard is "request-no-cors" and
+    //    name/value is not a no-CORS-safelisted request-header,
+    //    return.
+    // 6. Otherwise, if this’s guard is "response" and name is a
+    //    forbidden response-header name, return.
+    // Note: undici does not implement forbidden header names
+    if (this[kGuard] === 'immutable') {
+      throw new TypeError('immutable')
+    } else if (this[kGuard] === 'request-no-cors') {
+      // TODO
+    }
+
+    // 7. Set (name, value) in this’s header list.
+    // 8. If this’s guard is "request-no-cors", then remove
+    //    privileged no-CORS request headers from this
+    this[kHeadersList].set(name, value)
+  }
+
+  // https://fetch.spec.whatwg.org/#dom-headers-getsetcookie
+  getSetCookie () {
+    webidl.brandCheck(this, Headers)
+
+    // 1. If this’s header list does not contain `Set-Cookie`, then return « ».
+    // 2. Return the values of all headers in this’s header list whose name is
+    //    a byte-case-insensitive match for `Set-Cookie`, in order.
+
+    const list = this[kHeadersList].cookies
+
+    if (list) {
+      return [...list]
+    }
+
+    return []
+  }
+
+  // https://fetch.spec.whatwg.org/#concept-header-list-sort-and-combine
+  get [kHeadersSortedMap] () {
+    if (this[kHeadersList][kHeadersSortedMap]) {
+      return this[kHeadersList][kHeadersSortedMap]
+    }
+
+    // 1. Let headers be an empty list of headers with the key being the name
+    //    and value the value.
+    const headers = []
+
+    // 2. Let names be the result of convert header names to a sorted-lowercase
+    //    set with all the names of the headers in list.
+    const names = [...this[kHeadersList]].sort((a, b) => a[0] < b[0] ? -1 : 1)
+    const cookies = this[kHeadersList].cookies
+
+    // 3. For each name of names:
+    for (let i = 0; i < names.length; ++i) {
+      const [name, value] = names[i]
+      // 1. If name is `set-cookie`, then:
+      if (name === 'set-cookie') {
+        // 1. Let values be a list of all values of headers in list whose name
+        //    is a byte-case-insensitive match for name, in order.
+
+        // 2. For each value of values:
+        // 1. Append (name, value) to headers.
+        for (let j = 0; j < cookies.length; ++j) {
+          headers.push([name, cookies[j]])
+        }
+      } else {
+        // 2. Otherwise:
+
+        // 1. Let value be the result of getting name from list.
+
+        // 2. Assert: value is non-null.
+        assert(value !== null)
+
+        // 3. Append (name, value) to headers.
+        headers.push([name, value])
+      }
+    }
+
+    this[kHeadersList][kHeadersSortedMap] = headers
+
+    // 4. Return headers.
+    return headers
+  }
+
+  keys () {
+    webidl.brandCheck(this, Headers)
+
+    if (this[kGuard] === 'immutable') {
+      const value = this[kHeadersSortedMap]
+      return makeIterator(() => value, 'Headers',
+        'key')
+    }
+
+    return makeIterator(
+      () => [...this[kHeadersSortedMap].values()],
+      'Headers',
+      'key'
+    )
+  }
+
+  values () {
+    webidl.brandCheck(this, Headers)
+
+    if (this[kGuard] === 'immutable') {
+      const value = this[kHeadersSortedMap]
+      return makeIterator(() => value, 'Headers',
+        'value')
+    }
+
+    return makeIterator(
+      () => [...this[kHeadersSortedMap].values()],
+      'Headers',
+      'value'
+    )
+  }
+
+  entries () {
+    webidl.brandCheck(this, Headers)
+
+    if (this[kGuard] === 'immutable') {
+      const value = this[kHeadersSortedMap]
+      return makeIterator(() => value, 'Headers',
+        'key+value')
+    }
+
+    return makeIterator(
+      () => [...this[kHeadersSortedMap].values()],
+      'Headers',
+      'key+value'
+    )
+  }
+
+  /**
+   * @param {(value: string, key: string, self: Headers) => void} callbackFn
+   * @param {unknown} thisArg
+   */
+  forEach (callbackFn, thisArg = globalThis) {
+    webidl.brandCheck(this, Headers)
+
+    webidl.argumentLengthCheck(arguments, 1, { header: 'Headers.forEach' })
+
+    if (typeof callbackFn !== 'function') {
+      throw new TypeError(
+        "Failed to execute 'forEach' on 'Headers': parameter 1 is not of type 'Function'."
+      )
+    }
+
+    for (const [key, value] of this) {
+      callbackFn.apply(thisArg, [value, key, this])
+    }
+  }
+
+  [Symbol.for('nodejs.util.inspect.custom')] () {
+    webidl.brandCheck(this, Headers)
+
+    return this[kHeadersList]
+  }
+}
+
+Headers.prototype[Symbol.iterator] = Headers.prototype.entries
+
+Object.defineProperties(Headers.prototype, {
+  append: kEnumerableProperty,
+  delete: kEnumerableProperty,
+  get: kEnumerableProperty,
+  has: kEnumerableProperty,
+  set: kEnumerableProperty,
+  getSetCookie: kEnumerableProperty,
+  keys: kEnumerableProperty,
+  values: kEnumerableProperty,
+  entries: kEnumerableProperty,
+  forEach: kEnumerableProperty,
+  [Symbol.iterator]: { enumerable: false },
+  [Symbol.toStringTag]: {
+    value: 'Headers',
+    configurable: true
+  }
+})
+
+webidl.converters.HeadersInit = function (V) {
+  if (webidl.util.Type(V) === 'Object') {
+    if (V[Symbol.iterator]) {
+      return webidl.converters['sequence<sequence<ByteString>>'](V)
+    }
+
+    return webidl.converters['record<ByteString, ByteString>'](V)
+  }
+
+  throw webidl.errors.conversionFailed({
+    prefix: 'Headers constructor',
+    argument: 'Argument 1',
+    types: ['sequence<sequence<ByteString>>', 'record<ByteString, ByteString>']
+  })
+}
+
+module.exports = {
+  fill,
+  Headers,
+  HeadersList
+}
diff --git a/lib/fetch/index.js b/lib/fetch/index.js
new file mode 100644
index 0000000..17c3d87
--- /dev/null
+++ b/lib/fetch/index.js
@@ -0,0 +1,2145 @@
+// https://github.com/Ethan-Arrowood/undici-fetch
+
+'use strict'
+
+const {
+  Response,
+  makeNetworkError,
+  makeAppropriateNetworkError,
+  filterResponse,
+  makeResponse
+} = require('./response')
+const { Headers } = require('./headers')
+const { Request, makeRequest } = require('./request')
+const zlib = require('zlib')
+const {
+  bytesMatch,
+  makePolicyContainer,
+  clonePolicyContainer,
+  requestBadPort,
+  TAOCheck,
+  appendRequestOriginHeader,
+  responseLocationURL,
+  requestCurrentURL,
+  setRequestReferrerPolicyOnRedirect,
+  tryUpgradeRequestToAPotentiallyTrustworthyURL,
+  createOpaqueTimingInfo,
+  appendFetchMetadata,
+  corsCheck,
+  crossOriginResourcePolicyCheck,
+  determineRequestsReferrer,
+  coarsenedSharedCurrentTime,
+  createDeferredPromise,
+  isBlobLike,
+  sameOrigin,
+  isCancelled,
+  isAborted,
+  isErrorLike,
+  fullyReadBody,
+  readableStreamClose,
+  isomorphicEncode,
+  urlIsLocal,
+  urlIsHttpHttpsScheme,
+  urlHasHttpsScheme
+} = require('./util')
+const { kState, kHeaders, kGuard, kRealm } = require('./symbols')
+const assert = require('assert')
+const { safelyExtractBody } = require('./body')
+const {
+  redirectStatusSet,
+  nullBodyStatus,
+  safeMethodsSet,
+  requestBodyHeader,
+  subresourceSet,
+  DOMException
+} = require('./constants')
+const { kHeadersList } = require('../core/symbols')
+const EE = require('events')
+const { Readable, pipeline } = require('stream')
+const { addAbortListener, isErrored, isReadable, nodeMajor, nodeMinor } = require('../core/util')
+const { dataURLProcessor, serializeAMimeType } = require('./dataURL')
+const { TransformStream } = require('stream/web')
+const { getGlobalDispatcher } = require('../global')
+const { webidl } = require('./webidl')
+const { STATUS_CODES } = require('http')
+const GET_OR_HEAD = ['GET', 'HEAD']
+
+/** @type {import('buffer').resolveObjectURL} */
+let resolveObjectURL
+let ReadableStream = globalThis.ReadableStream
+
+class Fetch extends EE {
+  constructor (dispatcher) {
+    super()
+
+    this.dispatcher = dispatcher
+    this.connection = null
+    this.dump = false
+    this.state = 'ongoing'
+    // 2 terminated listeners get added per request,
+    // but only 1 gets removed. If there are 20 redirects,
+    // 21 listeners will be added.
+    // See https://github.com/nodejs/undici/issues/1711
+    // TODO (fix): Find and fix root cause for leaked listener.
+    this.setMaxListeners(21)
+  }
+
+  terminate (reason) {
+    if (this.state !== 'ongoing') {
+      return
+    }
+
+    this.state = 'terminated'
+    this.connection?.destroy(reason)
+    this.emit('terminated', reason)
+  }
+
+  // https://fetch.spec.whatwg.org/#fetch-controller-abort
+  abort (error) {
+    if (this.state !== 'ongoing') {
+      return
+    }
+
+    // 1. Set controller’s state to "aborted".
+    this.state = 'aborted'
+
+    // 2. Let fallbackError be an "AbortError" DOMException.
+    // 3. Set error to fallbackError if it is not given.
+    if (!error) {
+      error = new DOMException('The operation was aborted.', 'AbortError')
+    }
+
+    // 4. Let serializedError be StructuredSerialize(error).
+    //    If that threw an exception, catch it, and let
+    //    serializedError be StructuredSerialize(fallbackError).
+
+    // 5. Set controller’s serialized abort reason to serializedError.
+    this.serializedAbortReason = error
+
+    this.connection?.destroy(error)
+    this.emit('terminated', error)
+  }
+}
+
+// https://fetch.spec.whatwg.org/#fetch-method
+function fetch (input, init = {}) {
+  webidl.argumentLengthCheck(arguments, 1, { header: 'globalThis.fetch' })
+
+  // 1. Let p be a new promise.
+  const p = createDeferredPromise()
+
+  // 2. Let requestObject be the result of invoking the initial value of
+  // Request as constructor with input and init as arguments. If this throws
+  // an exception, reject p with it and return p.
+  let requestObject
+
+  try {
+    requestObject = new Request(input, init)
+  } catch (e) {
+    p.reject(e)
+    return p.promise
+  }
+
+  // 3. Let request be requestObject’s request.
+  const request = requestObject[kState]
+
+  // 4. If requestObject’s signal’s aborted flag is set, then:
+  if (requestObject.signal.aborted) {
+    // 1. Abort the fetch() call with p, request, null, and
+    //    requestObject’s signal’s abort reason.
+    abortFetch(p, request, null, requestObject.signal.reason)
+
+    // 2. Return p.
+    return p.promise
+  }
+
+  // 5. Let globalObject be request’s client’s global object.
+  const globalObject = request.client.globalObject
+
+  // 6. If globalObject is a ServiceWorkerGlobalScope object, then set
+  // request’s service-workers mode to "none".
+  if (globalObject?.constructor?.name === 'ServiceWorkerGlobalScope') {
+    request.serviceWorkers = 'none'
+  }
+
+  // 7. Let responseObject be null.
+  let responseObject = null
+
+  // 8. Let relevantRealm be this’s relevant Realm.
+  const relevantRealm = null
+
+  // 9. Let locallyAborted be false.
+  let locallyAborted = false
+
+  // 10. Let controller be null.
+  let controller = null
+
+  // 11. Add the following abort steps to requestObject’s signal:
+  addAbortListener(
+    requestObject.signal,
+    () => {
+      // 1. Set locallyAborted to true.
+      locallyAborted = true
+
+      // 2. Assert: controller is non-null.
+      assert(controller != null)
+
+      // 3. Abort controller with requestObject’s signal’s abort reason.
+      controller.abort(requestObject.signal.reason)
+
+      // 4. Abort the fetch() call with p, request, responseObject,
+      //    and requestObject’s signal’s abort reason.
+      abortFetch(p, request, responseObject, requestObject.signal.reason)
+    }
+  )
+
+  // 12. Let handleFetchDone given response response be to finalize and
+  // report timing with response, globalObject, and "fetch".
+  const handleFetchDone = (response) =>
+    finalizeAndReportTiming(response, 'fetch')
+
+  // 13. Set controller to the result of calling fetch given request,
+  // with processResponseEndOfBody set to handleFetchDone, and processResponse
+  // given response being these substeps:
+
+  const processResponse = (response) => {
+    // 1. If locallyAborted is true, terminate these substeps.
+    if (locallyAborted) {
+      return Promise.resolve()
+    }
+
+    // 2. If response’s aborted flag is set, then:
+    if (response.aborted) {
+      // 1. Let deserializedError be the result of deserialize a serialized
+      //    abort reason given controller’s serialized abort reason and
+      //    relevantRealm.
+
+      // 2. Abort the fetch() call with p, request, responseObject, and
+      //    deserializedError.
+
+      abortFetch(p, request, responseObject, controller.serializedAbortReason)
+      return Promise.resolve()
+    }
+
+    // 3. If response is a network error, then reject p with a TypeError
+    // and terminate these substeps.
+    if (response.type === 'error') {
+      p.reject(
+        Object.assign(new TypeError('fetch failed'), { cause: response.error })
+      )
+      return Promise.resolve()
+    }
+
+    // 4. Set responseObject to the result of creating a Response object,
+    // given response, "immutable", and relevantRealm.
+    responseObject = new Response()
+    responseObject[kState] = response
+    responseObject[kRealm] = relevantRealm
+    responseObject[kHeaders][kHeadersList] = response.headersList
+    responseObject[kHeaders][kGuard] = 'immutable'
+    responseObject[kHeaders][kRealm] = relevantRealm
+
+    // 5. Resolve p with responseObject.
+    p.resolve(responseObject)
+  }
+
+  controller = fetching({
+    request,
+    processResponseEndOfBody: handleFetchDone,
+    processResponse,
+    dispatcher: init.dispatcher ?? getGlobalDispatcher() // undici
+  })
+
+  // 14. Return p.
+  return p.promise
+}
+
+// https://fetch.spec.whatwg.org/#finalize-and-report-timing
+function finalizeAndReportTiming (response, initiatorType = 'other') {
+  // 1. If response is an aborted network error, then return.
+  if (response.type === 'error' && response.aborted) {
+    return
+  }
+
+  // 2. If response’s URL list is null or empty, then return.
+  if (!response.urlList?.length) {
+    return
+  }
+
+  // 3. Let originalURL be response’s URL list[0].
+  const originalURL = response.urlList[0]
+
+  // 4. Let timingInfo be response’s timing info.
+  let timingInfo = response.timingInfo
+
+  // 5. Let cacheState be response’s cache state.
+  let cacheState = response.cacheState
+
+  // 6. If originalURL’s scheme is not an HTTP(S) scheme, then return.
+  if (!urlIsHttpHttpsScheme(originalURL)) {
+    return
+  }
+
+  // 7. If timingInfo is null, then return.
+  if (timingInfo === null) {
+    return
+  }
+
+  // 8. If response’s timing allow passed flag is not set, then:
+  if (!response.timingAllowPassed) {
+    //  1. Set timingInfo to a the result of creating an opaque timing info for timingInfo.
+    timingInfo = createOpaqueTimingInfo({
+      startTime: timingInfo.startTime
+    })
+
+    //  2. Set cacheState to the empty string.
+    cacheState = ''
+  }
+
+  // 9. Set timingInfo’s end time to the coarsened shared current time
+  // given global’s relevant settings object’s cross-origin isolated
+  // capability.
+  // TODO: given global’s relevant settings object’s cross-origin isolated
+  // capability?
+  timingInfo.endTime = coarsenedSharedCurrentTime()
+
+  // 10. Set response’s timing info to timingInfo.
+  response.timingInfo = timingInfo
+
+  // 11. Mark resource timing for timingInfo, originalURL, initiatorType,
+  // global, and cacheState.
+  markResourceTiming(
+    timingInfo,
+    originalURL,
+    initiatorType,
+    globalThis,
+    cacheState
+  )
+}
+
+// https://w3c.github.io/resource-timing/#dfn-mark-resource-timing
+function markResourceTiming (timingInfo, originalURL, initiatorType, globalThis, cacheState) {
+  if (nodeMajor > 18 || (nodeMajor === 18 && nodeMinor >= 2)) {
+    performance.markResourceTiming(timingInfo, originalURL.href, initiatorType, globalThis, cacheState)
+  }
+}
+
+// https://fetch.spec.whatwg.org/#abort-fetch
+function abortFetch (p, request, responseObject, error) {
+  // Note: AbortSignal.reason was added in node v17.2.0
+  // which would give us an undefined error to reject with.
+  // Remove this once node v16 is no longer supported.
+  if (!error) {
+    error = new DOMException('The operation was aborted.', 'AbortError')
+  }
+
+  // 1. Reject promise with error.
+  p.reject(error)
+
+  // 2. If request’s body is not null and is readable, then cancel request’s
+  // body with error.
+  if (request.body != null && isReadable(request.body?.stream)) {
+    request.body.stream.cancel(error).catch((err) => {
+      if (err.code === 'ERR_INVALID_STATE') {
+        // Node bug?
+        return
+      }
+      throw err
+    })
+  }
+
+  // 3. If responseObject is null, then return.
+  if (responseObject == null) {
+    return
+  }
+
+  // 4. Let response be responseObject’s response.
+  const response = responseObject[kState]
+
+  // 5. If response’s body is not null and is readable, then error response’s
+  // body with error.
+  if (response.body != null && isReadable(response.body?.stream)) {
+    response.body.stream.cancel(error).catch((err) => {
+      if (err.code === 'ERR_INVALID_STATE') {
+        // Node bug?
+        return
+      }
+      throw err
+    })
+  }
+}
+
+// https://fetch.spec.whatwg.org/#fetching
+function fetching ({
+  request,
+  processRequestBodyChunkLength,
+  processRequestEndOfBody,
+  processResponse,
+  processResponseEndOfBody,
+  processResponseConsumeBody,
+  useParallelQueue = false,
+  dispatcher // undici
+}) {
+  // 1. Let taskDestination be null.
+  let taskDestination = null
+
+  // 2. Let crossOriginIsolatedCapability be false.
+  let crossOriginIsolatedCapability = false
+
+  // 3. If request’s client is non-null, then:
+  if (request.client != null) {
+    // 1. Set taskDestination to request’s client’s global object.
+    taskDestination = request.client.globalObject
+
+    // 2. Set crossOriginIsolatedCapability to request’s client’s cross-origin
+    // isolated capability.
+    crossOriginIsolatedCapability =
+      request.client.crossOriginIsolatedCapability
+  }
+
+  // 4. If useParallelQueue is true, then set taskDestination to the result of
+  // starting a new parallel queue.
+  // TODO
+
+  // 5. Let timingInfo be a new fetch timing info whose start time and
+  // post-redirect start time are the coarsened shared current time given
+  // crossOriginIsolatedCapability.
+  const currenTime = coarsenedSharedCurrentTime(crossOriginIsolatedCapability)
+  const timingInfo = createOpaqueTimingInfo({
+    startTime: currenTime
+  })
+
+  // 6. Let fetchParams be a new fetch params whose
+  // request is request,
+  // timing info is timingInfo,
+  // process request body chunk length is processRequestBodyChunkLength,
+  // process request end-of-body is processRequestEndOfBody,
+  // process response is processResponse,
+  // process response consume body is processResponseConsumeBody,
+  // process response end-of-body is processResponseEndOfBody,
+  // task destination is taskDestination,
+  // and cross-origin isolated capability is crossOriginIsolatedCapability.
+  const fetchParams = {
+    controller: new Fetch(dispatcher),
+    request,
+    timingInfo,
+    processRequestBodyChunkLength,
+    processRequestEndOfBody,
+    processResponse,
+    processResponseConsumeBody,
+    processResponseEndOfBody,
+    taskDestination,
+    crossOriginIsolatedCapability
+  }
+
+  // 7. If request’s body is a byte sequence, then set request’s body to
+  //    request’s body as a body.
+  // NOTE: Since fetching is only called from fetch, body should already be
+  // extracted.
+  assert(!request.body || request.body.stream)
+
+  // 8. If request’s window is "client", then set request’s window to request’s
+  // client, if request’s client’s global object is a Window object; otherwise
+  // "no-window".
+  if (request.window === 'client') {
+    // TODO: What if request.client is null?
+    request.window =
+      request.client?.globalObject?.constructor?.name === 'Window'
+        ? request.client
+        : 'no-window'
+  }
+
+  // 9. If request’s origin is "client", then set request’s origin to request’s
+  // client’s origin.
+  if (request.origin === 'client') {
+    // TODO: What if request.client is null?
+    request.origin = request.client?.origin
+  }
+
+  // 10. If all of the following conditions are true:
+  // TODO
+
+  // 11. If request’s policy container is "client", then:
+  if (request.policyContainer === 'client') {
+    // 1. If request’s client is non-null, then set request’s policy
+    // container to a clone of request’s client’s policy container. [HTML]
+    if (request.client != null) {
+      request.policyContainer = clonePolicyContainer(
+        request.client.policyContainer
+      )
+    } else {
+      // 2. Otherwise, set request’s policy container to a new policy
+      // container.
+      request.policyContainer = makePolicyContainer()
+    }
+  }
+
+  // 12. If request’s header list does not contain `Accept`, then:
+  if (!request.headersList.contains('accept')) {
+    // 1. Let value be `*/*`.
+    const value = '*/*'
+
+    // 2. A user agent should set value to the first matching statement, if
+    // any, switching on request’s destination:
+    // "document"
+    // "frame"
+    // "iframe"
+    // `text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8`
+    // "image"
+    // `image/png,image/svg+xml,image/*;q=0.8,*/*;q=0.5`
+    // "style"
+    // `text/css,*/*;q=0.1`
+    // TODO
+
+    // 3. Append `Accept`/value to request’s header list.
+    request.headersList.append('accept', value)
+  }
+
+  // 13. If request’s header list does not contain `Accept-Language`, then
+  // user agents should append `Accept-Language`/an appropriate value to
+  // request’s header list.
+  if (!request.headersList.contains('accept-language')) {
+    request.headersList.append('accept-language', '*')
+  }
+
+  // 14. If request’s priority is null, then use request’s initiator and
+  // destination appropriately in setting request’s priority to a
+  // user-agent-defined object.
+  if (request.priority === null) {
+    // TODO
+  }
+
+  // 15. If request is a subresource request, then:
+  if (subresourceSet.has(request.destination)) {
+    // TODO
+  }
+
+  // 16. Run main fetch given fetchParams.
+  mainFetch(fetchParams)
+    .catch(err => {
+      fetchParams.controller.terminate(err)
+    })
+
+  // 17. Return fetchParam's controller
+  return fetchParams.controller
+}
+
+// https://fetch.spec.whatwg.org/#concept-main-fetch
+async function mainFetch (fetchParams, recursive = false) {
+  // 1. Let request be fetchParams’s request.
+  const request = fetchParams.request
+
+  // 2. Let response be null.
+  let response = null
+
+  // 3. If request’s local-URLs-only flag is set and request’s current URL is
+  // not local, then set response to a network error.
+  if (request.localURLsOnly && !urlIsLocal(requestCurrentURL(request))) {
+    response = makeNetworkError('local URLs only')
+  }
+
+  // 4. Run report Content Security Policy violations for request.
+  // TODO
+
+  // 5. Upgrade request to a potentially trustworthy URL, if appropriate.
+  tryUpgradeRequestToAPotentiallyTrustworthyURL(request)
+
+  // 6. If should request be blocked due to a bad port, should fetching request
+  // be blocked as mixed content, or should request be blocked by Content
+  // Security Policy returns blocked, then set response to a network error.
+  if (requestBadPort(request) === 'blocked') {
+    response = makeNetworkError('bad port')
+  }
+  // TODO: should fetching request be blocked as mixed content?
+  // TODO: should request be blocked by Content Security Policy?
+
+  // 7. If request’s referrer policy is the empty string, then set request’s
+  // referrer policy to request’s policy container’s referrer policy.
+  if (request.referrerPolicy === '') {
+    request.referrerPolicy = request.policyContainer.referrerPolicy
+  }
+
+  // 8. If request’s referrer is not "no-referrer", then set request’s
+  // referrer to the result of invoking determine request’s referrer.
+  if (request.referrer !== 'no-referrer') {
+    request.referrer = determineRequestsReferrer(request)
+  }
+
+  // 9. Set request’s current URL’s scheme to "https" if all of the following
+  // conditions are true:
+  // - request’s current URL’s scheme is "http"
+  // - request’s current URL’s host is a domain
+  // - Matching request’s current URL’s host per Known HSTS Host Domain Name
+  //   Matching results in either a superdomain match with an asserted
+  //   includeSubDomains directive or a congruent match (with or without an
+  //   asserted includeSubDomains directive). [HSTS]
+  // TODO
+
+  // 10. If recursive is false, then run the remaining steps in parallel.
+  // TODO
+
+  // 11. If response is null, then set response to the result of running
+  // the steps corresponding to the first matching statement:
+  if (response === null) {
+    response = await (async () => {
+      const currentURL = requestCurrentURL(request)
+
+      if (
+        // - request’s current URL’s origin is same origin with request’s origin,
+        //   and request’s response tainting is "basic"
+        (sameOrigin(currentURL, request.url) && request.responseTainting === 'basic') ||
+        // request’s current URL’s scheme is "data"
+        (currentURL.protocol === 'data:') ||
+        // - request’s mode is "navigate" or "websocket"
+        (request.mode === 'navigate' || request.mode === 'websocket')
+      ) {
+        // 1. Set request’s response tainting to "basic".
+        request.responseTainting = 'basic'
+
+        // 2. Return the result of running scheme fetch given fetchParams.
+        return await schemeFetch(fetchParams)
+      }
+
+      // request’s mode is "same-origin"
+      if (request.mode === 'same-origin') {
+        // 1. Return a network error.
+        return makeNetworkError('request mode cannot be "same-origin"')
+      }
+
+      // request’s mode is "no-cors"
+      if (request.mode === 'no-cors') {
+        // 1. If request’s redirect mode is not "follow", then return a network
+        // error.
+        if (request.redirect !== 'follow') {
+          return makeNetworkError(
+            'redirect mode cannot be "follow" for "no-cors" request'
+          )
+        }
+
+        // 2. Set request’s response tainting to "opaque".
+        request.responseTainting = 'opaque'
+
+        // 3. Return the result of running scheme fetch given fetchParams.
+        return await schemeFetch(fetchParams)
+      }
+
+      // request’s current URL’s scheme is not an HTTP(S) scheme
+      if (!urlIsHttpHttpsScheme(requestCurrentURL(request))) {
+        // Return a network error.
+        return makeNetworkError('URL scheme must be a HTTP(S) scheme')
+      }
+
+      // - request’s use-CORS-preflight flag is set
+      // - request’s unsafe-request flag is set and either request’s method is
+      //   not a CORS-safelisted method or CORS-unsafe request-header names with
+      //   request’s header list is not empty
+      //    1. Set request’s response tainting to "cors".
+      //    2. Let corsWithPreflightResponse be the result of running HTTP fetch
+      //    given fetchParams and true.
+      //    3. If corsWithPreflightResponse is a network error, then clear cache
+      //    entries using request.
+      //    4. Return corsWithPreflightResponse.
+      // TODO
+
+      // Otherwise
+      //    1. Set request’s response tainting to "cors".
+      request.responseTainting = 'cors'
+
+      //    2. Return the result of running HTTP fetch given fetchParams.
+      return await httpFetch(fetchParams)
+    })()
+  }
+
+  // 12. If recursive is true, then return response.
+  if (recursive) {
+    return response
+  }
+
+  // 13. If response is not a network error and response is not a filtered
+  // response, then:
+  if (response.status !== 0 && !response.internalResponse) {
+    // If request’s response tainting is "cors", then:
+    if (request.responseTainting === 'cors') {
+      // 1. Let headerNames be the result of extracting header list values
+      // given `Access-Control-Expose-Headers` and response’s header list.
+      // TODO
+      // 2. If request’s credentials mode is not "include" and headerNames
+      // contains `*`, then set response’s CORS-exposed header-name list to
+      // all unique header names in response’s header list.
+      // TODO
+      // 3. Otherwise, if headerNames is not null or failure, then set
+      // response’s CORS-exposed header-name list to headerNames.
+      // TODO
+    }
+
+    // Set response to the following filtered response with response as its
+    // internal response, depending on request’s response tainting:
+    if (request.responseTainting === 'basic') {
+      response = filterResponse(response, 'basic')
+    } else if (request.responseTainting === 'cors') {
+      response = filterResponse(response, 'cors')
+    } else if (request.responseTainting === 'opaque') {
+      response = filterResponse(response, 'opaque')
+    } else {
+      assert(false)
+    }
+  }
+
+  // 14. Let internalResponse be response, if response is a network error,
+  // and response’s internal response otherwise.
+  let internalResponse =
+    response.status === 0 ? response : response.internalResponse
+
+  // 15. If internalResponse’s URL list is empty, then set it to a clone of
+  // request’s URL list.
+  if (internalResponse.urlList.length === 0) {
+    internalResponse.urlList.push(...request.urlList)
+  }
+
+  // 16. If request’s timing allow failed flag is unset, then set
+  // internalResponse’s timing allow passed flag.
+  if (!request.timingAllowFailed) {
+    response.timingAllowPassed = true
+  }
+
+  // 17. If response is not a network error and any of the following returns
+  // blocked
+  // - should internalResponse to request be blocked as mixed content
+  // - should internalResponse to request be blocked by Content Security Policy
+  // - should internalResponse to request be blocked due to its MIME type
+  // - should internalResponse to request be blocked due to nosniff
+  // TODO
+
+  // 18. If response’s type is "opaque", internalResponse’s status is 206,
+  // internalResponse’s range-requested flag is set, and request’s header
+  // list does not contain `Range`, then set response and internalResponse
+  // to a network error.
+  if (
+    response.type === 'opaque' &&
+    internalResponse.status === 206 &&
+    internalResponse.rangeRequested &&
+    !request.headers.contains('range')
+  ) {
+    response = internalResponse = makeNetworkError()
+  }
+
+  // 19. If response is not a network error and either request’s method is
+  // `HEAD` or `CONNECT`, or internalResponse’s status is a null body status,
+  // set internalResponse’s body to null and disregard any enqueuing toward
+  // it (if any).
+  if (
+    response.status !== 0 &&
+    (request.method === 'HEAD' ||
+      request.method === 'CONNECT' ||
+      nullBodyStatus.includes(internalResponse.status))
+  ) {
+    internalResponse.body = null
+    fetchParams.controller.dump = true
+  }
+
+  // 20. If request’s integrity metadata is not the empty string, then:
+  if (request.integrity) {
+    // 1. Let processBodyError be this step: run fetch finale given fetchParams
+    // and a network error.
+    const processBodyError = (reason) =>
+      fetchFinale(fetchParams, makeNetworkError(reason))
+
+    // 2. If request’s response tainting is "opaque", or response’s body is null,
+    // then run processBodyError and abort these steps.
+    if (request.responseTainting === 'opaque' || response.body == null) {
+      processBodyError(response.error)
+      return
+    }
+
+    // 3. Let processBody given bytes be these steps:
+    const processBody = (bytes) => {
+      // 1. If bytes do not match request’s integrity metadata,
+      // then run processBodyError and abort these steps. [SRI]
+      if (!bytesMatch(bytes, request.integrity)) {
+        processBodyError('integrity mismatch')
+        return
+      }
+
+      // 2. Set response’s body to bytes as a body.
+      response.body = safelyExtractBody(bytes)[0]
+
+      // 3. Run fetch finale given fetchParams and response.
+      fetchFinale(fetchParams, response)
+    }
+
+    // 4. Fully read response’s body given processBody and processBodyError.
+    await fullyReadBody(response.body, processBody, processBodyError)
+  } else {
+    // 21. Otherwise, run fetch finale given fetchParams and response.
+    fetchFinale(fetchParams, response)
+  }
+}
+
+// https://fetch.spec.whatwg.org/#concept-scheme-fetch
+// given a fetch params fetchParams
+function schemeFetch (fetchParams) {
+  // Note: since the connection is destroyed on redirect, which sets fetchParams to a
+  // cancelled state, we do not want this condition to trigger *unless* there have been
+  // no redirects. See https://github.com/nodejs/undici/issues/1776
+  // 1. If fetchParams is canceled, then return the appropriate network error for fetchParams.
+  if (isCancelled(fetchParams) && fetchParams.request.redirectCount === 0) {
+    return Promise.resolve(makeAppropriateNetworkError(fetchParams))
+  }
+
+  // 2. Let request be fetchParams’s request.
+  const { request } = fetchParams
+
+  const { protocol: scheme } = requestCurrentURL(request)
+
+  // 3. Switch on request’s current URL’s scheme and run the associated steps:
+  switch (scheme) {
+    case 'about:': {
+      // If request’s current URL’s path is the string "blank", then return a new response
+      // whose status message is `OK`, header list is « (`Content-Type`, `text/html;charset=utf-8`) »,
+      // and body is the empty byte sequence as a body.
+
+      // Otherwise, return a network error.
+      return Promise.resolve(makeNetworkError('about scheme is not supported'))
+    }
+    case 'blob:': {
+      if (!resolveObjectURL) {
+        resolveObjectURL = require('buffer').resolveObjectURL
+      }
+
+      // 1. Let blobURLEntry be request’s current URL’s blob URL entry.
+      const blobURLEntry = requestCurrentURL(request)
+
+      // https://github.com/web-platform-tests/wpt/blob/7b0ebaccc62b566a1965396e5be7bb2bc06f841f/FileAPI/url/resources/fetch-tests.js#L52-L56
+      // Buffer.resolveObjectURL does not ignore URL queries.
+      if (blobURLEntry.search.length !== 0) {
+        return Promise.resolve(makeNetworkError('NetworkError when attempting to fetch resource.'))
+      }
+
+      const blobURLEntryObject = resolveObjectURL(blobURLEntry.toString())
+
+      // 2. If request’s method is not `GET`, blobURLEntry is null, or blobURLEntry’s
+      //    object is not a Blob object, then return a network error.
+      if (request.method !== 'GET' || !isBlobLike(blobURLEntryObject)) {
+        return Promise.resolve(makeNetworkError('invalid method'))
+      }
+
+      // 3. Let bodyWithType be the result of safely extracting blobURLEntry’s object.
+      const bodyWithType = safelyExtractBody(blobURLEntryObject)
+
+      // 4. Let body be bodyWithType’s body.
+      const body = bodyWithType[0]
+
+      // 5. Let length be body’s length, serialized and isomorphic encoded.
+      const length = isomorphicEncode(`${body.length}`)
+
+      // 6. Let type be bodyWithType’s type if it is non-null; otherwise the empty byte sequence.
+      const type = bodyWithType[1] ?? ''
+
+      // 7. Return a new response whose status message is `OK`, header list is
+      //    « (`Content-Length`, length), (`Content-Type`, type) », and body is body.
+      const response = makeResponse({
+        statusText: 'OK',
+        headersList: [
+          ['content-length', { name: 'Content-Length', value: length }],
+          ['content-type', { name: 'Content-Type', value: type }]
+        ]
+      })
+
+      response.body = body
+
+      return Promise.resolve(response)
+    }
+    case 'data:': {
+      // 1. Let dataURLStruct be the result of running the
+      //    data: URL processor on request’s current URL.
+      const currentURL = requestCurrentURL(request)
+      const dataURLStruct = dataURLProcessor(currentURL)
+
+      // 2. If dataURLStruct is failure, then return a
+      //    network error.
+      if (dataURLStruct === 'failure') {
+        return Promise.resolve(makeNetworkError('failed to fetch the data URL'))
+      }
+
+      // 3. Let mimeType be dataURLStruct’s MIME type, serialized.
+      const mimeType = serializeAMimeType(dataURLStruct.mimeType)
+
+      // 4. Return a response whose status message is `OK`,
+      //    header list is « (`Content-Type`, mimeType) »,
+      //    and body is dataURLStruct’s body as a body.
+      return Promise.resolve(makeResponse({
+        statusText: 'OK',
+        headersList: [
+          ['content-type', { name: 'Content-Type', value: mimeType }]
+        ],
+        body: safelyExtractBody(dataURLStruct.body)[0]
+      }))
+    }
+    case 'file:': {
+      // For now, unfortunate as it is, file URLs are left as an exercise for the reader.
+      // When in doubt, return a network error.
+      return Promise.resolve(makeNetworkError('not implemented... yet...'))
+    }
+    case 'http:':
+    case 'https:': {
+      // Return the result of running HTTP fetch given fetchParams.
+
+      return httpFetch(fetchParams)
+        .catch((err) => makeNetworkError(err))
+    }
+    default: {
+      return Promise.resolve(makeNetworkError('unknown scheme'))
+    }
+  }
+}
+
+// https://fetch.spec.whatwg.org/#finalize-response
+function finalizeResponse (fetchParams, response) {
+  // 1. Set fetchParams’s request’s done flag.
+  fetchParams.request.done = true
+
+  // 2, If fetchParams’s process response done is not null, then queue a fetch
+  // task to run fetchParams’s process response done given response, with
+  // fetchParams’s task destination.
+  if (fetchParams.processResponseDone != null) {
+    queueMicrotask(() => fetchParams.processResponseDone(response))
+  }
+}
+
+// https://fetch.spec.whatwg.org/#fetch-finale
+function fetchFinale (fetchParams, response) {
+  // 1. If response is a network error, then:
+  if (response.type === 'error') {
+    // 1. Set response’s URL list to « fetchParams’s request’s URL list[0] ».
+    response.urlList = [fetchParams.request.urlList[0]]
+
+    // 2. Set response’s timing info to the result of creating an opaque timing
+    // info for fetchParams’s timing info.
+    response.timingInfo = createOpaqueTimingInfo({
+      startTime: fetchParams.timingInfo.startTime
+    })
+  }
+
+  // 2. Let processResponseEndOfBody be the following steps:
+  const processResponseEndOfBody = () => {
+    // 1. Set fetchParams’s request’s done flag.
+    fetchParams.request.done = true
+
+    // If fetchParams’s process response end-of-body is not null,
+    // then queue a fetch task to run fetchParams’s process response
+    // end-of-body given response with fetchParams’s task destination.
+    if (fetchParams.processResponseEndOfBody != null) {
+      queueMicrotask(() => fetchParams.processResponseEndOfBody(response))
+    }
+  }
+
+  // 3. If fetchParams’s process response is non-null, then queue a fetch task
+  // to run fetchParams’s process response given response, with fetchParams’s
+  // task destination.
+  if (fetchParams.processResponse != null) {
+    queueMicrotask(() => fetchParams.processResponse(response))
+  }
+
+  // 4. If response’s body is null, then run processResponseEndOfBody.
+  if (response.body == null) {
+    processResponseEndOfBody()
+  } else {
+  // 5. Otherwise:
+
+    // 1. Let transformStream be a new a TransformStream.
+
+    // 2. Let identityTransformAlgorithm be an algorithm which, given chunk,
+    // enqueues chunk in transformStream.
+    const identityTransformAlgorithm = (chunk, controller) => {
+      controller.enqueue(chunk)
+    }
+
+    // 3. Set up transformStream with transformAlgorithm set to identityTransformAlgorithm
+    // and flushAlgorithm set to processResponseEndOfBody.
+    const transformStream = new TransformStream({
+      start () {},
+      transform: identityTransformAlgorithm,
+      flush: processResponseEndOfBody
+    }, {
+      size () {
+        return 1
+      }
+    }, {
+      size () {
+        return 1
+      }
+    })
+
+    // 4. Set response’s body to the result of piping response’s body through transformStream.
+    response.body = { stream: response.body.stream.pipeThrough(transformStream) }
+  }
+
+  // 6. If fetchParams’s process response consume body is non-null, then:
+  if (fetchParams.processResponseConsumeBody != null) {
+    // 1. Let processBody given nullOrBytes be this step: run fetchParams’s
+    // process response consume body given response and nullOrBytes.
+    const processBody = (nullOrBytes) => fetchParams.processResponseConsumeBody(response, nullOrBytes)
+
+    // 2. Let processBodyError be this step: run fetchParams’s process
+    // response consume body given response and failure.
+    const processBodyError = (failure) => fetchParams.processResponseConsumeBody(response, failure)
+
+    // 3. If response’s body is null, then queue a fetch task to run processBody
+    // given null, with fetchParams’s task destination.
+    if (response.body == null) {
+      queueMicrotask(() => processBody(null))
+    } else {
+      // 4. Otherwise, fully read response’s body given processBody, processBodyError,
+      // and fetchParams’s task destination.
+      return fullyReadBody(response.body, processBody, processBodyError)
+    }
+    return Promise.resolve()
+  }
+}
+
+// https://fetch.spec.whatwg.org/#http-fetch
+async function httpFetch (fetchParams) {
+  // 1. Let request be fetchParams’s request.
+  const request = fetchParams.request
+
+  // 2. Let response be null.
+  let response = null
+
+  // 3. Let actualResponse be null.
+  let actualResponse = null
+
+  // 4. Let timingInfo be fetchParams’s timing info.
+  const timingInfo = fetchParams.timingInfo
+
+  // 5. If request’s service-workers mode is "all", then:
+  if (request.serviceWorkers === 'all') {
+    // TODO
+  }
+
+  // 6. If response is null, then:
+  if (response === null) {
+    // 1. If makeCORSPreflight is true and one of these conditions is true:
+    // TODO
+
+    // 2. If request’s redirect mode is "follow", then set request’s
+    // service-workers mode to "none".
+    if (request.redirect === 'follow') {
+      request.serviceWorkers = 'none'
+    }
+
+    // 3. Set response and actualResponse to the result of running
+    // HTTP-network-or-cache fetch given fetchParams.
+    actualResponse = response = await httpNetworkOrCacheFetch(fetchParams)
+
+    // 4. If request’s response tainting is "cors" and a CORS check
+    // for request and response returns failure, then return a network error.
+    if (
+      request.responseTainting === 'cors' &&
+      corsCheck(request, response) === 'failure'
+    ) {
+      return makeNetworkError('cors failure')
+    }
+
+    // 5. If the TAO check for request and response returns failure, then set
+    // request’s timing allow failed flag.
+    if (TAOCheck(request, response) === 'failure') {
+      request.timingAllowFailed = true
+    }
+  }
+
+  // 7. If either request’s response tainting or response’s type
+  // is "opaque", and the cross-origin resource policy check with
+  // request’s origin, request’s client, request’s destination,
+  // and actualResponse returns blocked, then return a network error.
+  if (
+    (request.responseTainting === 'opaque' || response.type === 'opaque') &&
+    crossOriginResourcePolicyCheck(
+      request.origin,
+      request.client,
+      request.destination,
+      actualResponse
+    ) === 'blocked'
+  ) {
+    return makeNetworkError('blocked')
+  }
+
+  // 8. If actualResponse’s status is a redirect status, then:
+  if (redirectStatusSet.has(actualResponse.status)) {
+    // 1. If actualResponse’s status is not 303, request’s body is not null,
+    // and the connection uses HTTP/2, then user agents may, and are even
+    // encouraged to, transmit an RST_STREAM frame.
+    // See, https://github.com/whatwg/fetch/issues/1288
+    if (request.redirect !== 'manual') {
+      fetchParams.controller.connection.destroy()
+    }
+
+    // 2. Switch on request’s redirect mode:
+    if (request.redirect === 'error') {
+      // Set response to a network error.
+      response = makeNetworkError('unexpected redirect')
+    } else if (request.redirect === 'manual') {
+      // Set response to an opaque-redirect filtered response whose internal
+      // response is actualResponse.
+      // NOTE(spec): On the web this would return an `opaqueredirect` response,
+      // but that doesn't make sense server side.
+      // See https://github.com/nodejs/undici/issues/1193.
+      response = actualResponse
+    } else if (request.redirect === 'follow') {
+      // Set response to the result of running HTTP-redirect fetch given
+      // fetchParams and response.
+      response = await httpRedirectFetch(fetchParams, response)
+    } else {
+      assert(false)
+    }
+  }
+
+  // 9. Set response’s timing info to timingInfo.
+  response.timingInfo = timingInfo
+
+  // 10. Return response.
+  return response
+}
+
+// https://fetch.spec.whatwg.org/#http-redirect-fetch
+function httpRedirectFetch (fetchParams, response) {
+  // 1. Let request be fetchParams’s request.
+  const request = fetchParams.request
+
+  // 2. Let actualResponse be response, if response is not a filtered response,
+  // and response’s internal response otherwise.
+  const actualResponse = response.internalResponse
+    ? response.internalResponse
+    : response
+
+  // 3. Let locationURL be actualResponse’s location URL given request’s current
+  // URL’s fragment.
+  let locationURL
+
+  try {
+    locationURL = responseLocationURL(
+      actualResponse,
+      requestCurrentURL(request).hash
+    )
+
+    // 4. If locationURL is null, then return response.
+    if (locationURL == null) {
+      return response
+    }
+  } catch (err) {
+    // 5. If locationURL is failure, then return a network error.
+    return Promise.resolve(makeNetworkError(err))
+  }
+
+  // 6. If locationURL’s scheme is not an HTTP(S) scheme, then return a network
+  // error.
+  if (!urlIsHttpHttpsScheme(locationURL)) {
+    return Promise.resolve(makeNetworkError('URL scheme must be a HTTP(S) scheme'))
+  }
+
+  // 7. If request’s redirect count is 20, then return a network error.
+  if (request.redirectCount === 20) {
+    return Promise.resolve(makeNetworkError('redirect count exceeded'))
+  }
+
+  // 8. Increase request’s redirect count by 1.
+  request.redirectCount += 1
+
+  // 9. If request’s mode is "cors", locationURL includes credentials, and
+  // request’s origin is not same origin with locationURL’s origin, then return
+  //  a network error.
+  if (
+    request.mode === 'cors' &&
+    (locationURL.username || locationURL.password) &&
+    !sameOrigin(request, locationURL)
+  ) {
+    return Promise.resolve(makeNetworkError('cross origin not allowed for request mode "cors"'))
+  }
+
+  // 10. If request’s response tainting is "cors" and locationURL includes
+  // credentials, then return a network error.
+  if (
+    request.responseTainting === 'cors' &&
+    (locationURL.username || locationURL.password)
+  ) {
+    return Promise.resolve(makeNetworkError(
+      'URL cannot contain credentials for request mode "cors"'
+    ))
+  }
+
+  // 11. If actualResponse’s status is not 303, request’s body is non-null,
+  // and request’s body’s source is null, then return a network error.
+  if (
+    actualResponse.status !== 303 &&
+    request.body != null &&
+    request.body.source == null
+  ) {
+    return Promise.resolve(makeNetworkError())
+  }
+
+  // 12. If one of the following is true
+  // - actualResponse’s status is 301 or 302 and request’s method is `POST`
+  // - actualResponse’s status is 303 and request’s method is not `GET` or `HEAD`
+  if (
+    ([301, 302].includes(actualResponse.status) && request.method === 'POST') ||
+    (actualResponse.status === 303 &&
+      !GET_OR_HEAD.includes(request.method))
+  ) {
+    // then:
+    // 1. Set request’s method to `GET` and request’s body to null.
+    request.method = 'GET'
+    request.body = null
+
+    // 2. For each headerName of request-body-header name, delete headerName from
+    // request’s header list.
+    for (const headerName of requestBodyHeader) {
+      request.headersList.delete(headerName)
+    }
+  }
+
+  // 13. If request’s current URL’s origin is not same origin with locationURL’s
+  //     origin, then for each headerName of CORS non-wildcard request-header name,
+  //     delete headerName from request’s header list.
+  if (!sameOrigin(requestCurrentURL(request), locationURL)) {
+    // https://fetch.spec.whatwg.org/#cors-non-wildcard-request-header-name
+    request.headersList.delete('authorization')
+
+    // "Cookie" and "Host" are forbidden request-headers, which undici doesn't implement.
+    request.headersList.delete('cookie')
+    request.headersList.delete('host')
+  }
+
+  // 14. If request’s body is non-null, then set request’s body to the first return
+  // value of safely extracting request’s body’s source.
+  if (request.body != null) {
+    assert(request.body.source != null)
+    request.body = safelyExtractBody(request.body.source)[0]
+  }
+
+  // 15. Let timingInfo be fetchParams’s timing info.
+  const timingInfo = fetchParams.timingInfo
+
+  // 16. Set timingInfo’s redirect end time and post-redirect start time to the
+  // coarsened shared current time given fetchParams’s cross-origin isolated
+  // capability.
+  timingInfo.redirectEndTime = timingInfo.postRedirectStartTime =
+    coarsenedSharedCurrentTime(fetchParams.crossOriginIsolatedCapability)
+
+  // 17. If timingInfo’s redirect start time is 0, then set timingInfo’s
+  //  redirect start time to timingInfo’s start time.
+  if (timingInfo.redirectStartTime === 0) {
+    timingInfo.redirectStartTime = timingInfo.startTime
+  }
+
+  // 18. Append locationURL to request’s URL list.
+  request.urlList.push(locationURL)
+
+  // 19. Invoke set request’s referrer policy on redirect on request and
+  // actualResponse.
+  setRequestReferrerPolicyOnRedirect(request, actualResponse)
+
+  // 20. Return the result of running main fetch given fetchParams and true.
+  return mainFetch(fetchParams, true)
+}
+
+// https://fetch.spec.whatwg.org/#http-network-or-cache-fetch
+async function httpNetworkOrCacheFetch (
+  fetchParams,
+  isAuthenticationFetch = false,
+  isNewConnectionFetch = false
+) {
+  // 1. Let request be fetchParams’s request.
+  const request = fetchParams.request
+
+  // 2. Let httpFetchParams be null.
+  let httpFetchParams = null
+
+  // 3. Let httpRequest be null.
+  let httpRequest = null
+
+  // 4. Let response be null.
+  let response = null
+
+  // 5. Let storedResponse be null.
+  // TODO: cache
+
+  // 6. Let httpCache be null.
+  const httpCache = null
+
+  // 7. Let the revalidatingFlag be unset.
+  const revalidatingFlag = false
+
+  // 8. Run these steps, but abort when the ongoing fetch is terminated:
+
+  //    1. If request’s window is "no-window" and request’s redirect mode is
+  //    "error", then set httpFetchParams to fetchParams and httpRequest to
+  //    request.
+  if (request.window === 'no-window' && request.redirect === 'error') {
+    httpFetchParams = fetchParams
+    httpRequest = request
+  } else {
+    // Otherwise:
+
+    // 1. Set httpRequest to a clone of request.
+    httpRequest = makeRequest(request)
+
+    // 2. Set httpFetchParams to a copy of fetchParams.
+    httpFetchParams = { ...fetchParams }
+
+    // 3. Set httpFetchParams’s request to httpRequest.
+    httpFetchParams.request = httpRequest
+  }
+
+  //    3. Let includeCredentials be true if one of
+  const includeCredentials =
+    request.credentials === 'include' ||
+    (request.credentials === 'same-origin' &&
+      request.responseTainting === 'basic')
+
+  //    4. Let contentLength be httpRequest’s body’s length, if httpRequest’s
+  //    body is non-null; otherwise null.
+  const contentLength = httpRequest.body ? httpRequest.body.length : null
+
+  //    5. Let contentLengthHeaderValue be null.
+  let contentLengthHeaderValue = null
+
+  //    6. If httpRequest’s body is null and httpRequest’s method is `POST` or
+  //    `PUT`, then set contentLengthHeaderValue to `0`.
+  if (
+    httpRequest.body == null &&
+    ['POST', 'PUT'].includes(httpRequest.method)
+  ) {
+    contentLengthHeaderValue = '0'
+  }
+
+  //    7. If contentLength is non-null, then set contentLengthHeaderValue to
+  //    contentLength, serialized and isomorphic encoded.
+  if (contentLength != null) {
+    contentLengthHeaderValue = isomorphicEncode(`${contentLength}`)
+  }
+
+  //    8. If contentLengthHeaderValue is non-null, then append
+  //    `Content-Length`/contentLengthHeaderValue to httpRequest’s header
+  //    list.
+  if (contentLengthHeaderValue != null) {
+    httpRequest.headersList.append('content-length', contentLengthHeaderValue)
+  }
+
+  //    9. If contentLengthHeaderValue is non-null, then append (`Content-Length`,
+  //    contentLengthHeaderValue) to httpRequest’s header list.
+
+  //    10. If contentLength is non-null and httpRequest’s keepalive is true,
+  //    then:
+  if (contentLength != null && httpRequest.keepalive) {
+    // NOTE: keepalive is a noop outside of browser context.
+  }
+
+  //    11. If httpRequest’s referrer is a URL, then append
+  //    `Referer`/httpRequest’s referrer, serialized and isomorphic encoded,
+  //     to httpRequest’s header list.
+  if (httpRequest.referrer instanceof URL) {
+    httpRequest.headersList.append('referer', isomorphicEncode(httpRequest.referrer.href))
+  }
+
+  //    12. Append a request `Origin` header for httpRequest.
+  appendRequestOriginHeader(httpRequest)
+
+  //    13. Append the Fetch metadata headers for httpRequest. [FETCH-METADATA]
+  appendFetchMetadata(httpRequest)
+
+  //    14. If httpRequest’s header list does not contain `User-Agent`, then
+  //    user agents should append `User-Agent`/default `User-Agent` value to
+  //    httpRequest’s header list.
+  if (!httpRequest.headersList.contains('user-agent')) {
+    httpRequest.headersList.append('user-agent', typeof esbuildDetection === 'undefined' ? 'undici' : 'node')
+  }
+
+  //    15. If httpRequest’s cache mode is "default" and httpRequest’s header
+  //    list contains `If-Modified-Since`, `If-None-Match`,
+  //    `If-Unmodified-Since`, `If-Match`, or `If-Range`, then set
+  //    httpRequest’s cache mode to "no-store".
+  if (
+    httpRequest.cache === 'default' &&
+    (httpRequest.headersList.contains('if-modified-since') ||
+      httpRequest.headersList.contains('if-none-match') ||
+      httpRequest.headersList.contains('if-unmodified-since') ||
+      httpRequest.headersList.contains('if-match') ||
+      httpRequest.headersList.contains('if-range'))
+  ) {
+    httpRequest.cache = 'no-store'
+  }
+
+  //    16. If httpRequest’s cache mode is "no-cache", httpRequest’s prevent
+  //    no-cache cache-control header modification flag is unset, and
+  //    httpRequest’s header list does not contain `Cache-Control`, then append
+  //    `Cache-Control`/`max-age=0` to httpRequest’s header list.
+  if (
+    httpRequest.cache === 'no-cache' &&
+    !httpRequest.preventNoCacheCacheControlHeaderModification &&
+    !httpRequest.headersList.contains('cache-control')
+  ) {
+    httpRequest.headersList.append('cache-control', 'max-age=0')
+  }
+
+  //    17. If httpRequest’s cache mode is "no-store" or "reload", then:
+  if (httpRequest.cache === 'no-store' || httpRequest.cache === 'reload') {
+    // 1. If httpRequest’s header list does not contain `Pragma`, then append
+    // `Pragma`/`no-cache` to httpRequest’s header list.
+    if (!httpRequest.headersList.contains('pragma')) {
+      httpRequest.headersList.append('pragma', 'no-cache')
+    }
+
+    // 2. If httpRequest’s header list does not contain `Cache-Control`,
+    // then append `Cache-Control`/`no-cache` to httpRequest’s header list.
+    if (!httpRequest.headersList.contains('cache-control')) {
+      httpRequest.headersList.append('cache-control', 'no-cache')
+    }
+  }
+
+  //    18. If httpRequest’s header list contains `Range`, then append
+  //    `Accept-Encoding`/`identity` to httpRequest’s header list.
+  if (httpRequest.headersList.contains('range')) {
+    httpRequest.headersList.append('accept-encoding', 'identity')
+  }
+
+  //    19. Modify httpRequest’s header list per HTTP. Do not append a given
+  //    header if httpRequest’s header list contains that header’s name.
+  //    TODO: https://github.com/whatwg/fetch/issues/1285#issuecomment-896560129
+  if (!httpRequest.headersList.contains('accept-encoding')) {
+    if (urlHasHttpsScheme(requestCurrentURL(httpRequest))) {
+      httpRequest.headersList.append('accept-encoding', 'br, gzip, deflate')
+    } else {
+      httpRequest.headersList.append('accept-encoding', 'gzip, deflate')
+    }
+  }
+
+  httpRequest.headersList.delete('host')
+
+  //    20. If includeCredentials is true, then:
+  if (includeCredentials) {
+    // 1. If the user agent is not configured to block cookies for httpRequest
+    // (see section 7 of [COOKIES]), then:
+    // TODO: credentials
+    // 2. If httpRequest’s header list does not contain `Authorization`, then:
+    // TODO: credentials
+  }
+
+  //    21. If there’s a proxy-authentication entry, use it as appropriate.
+  //    TODO: proxy-authentication
+
+  //    22. Set httpCache to the result of determining the HTTP cache
+  //    partition, given httpRequest.
+  //    TODO: cache
+
+  //    23. If httpCache is null, then set httpRequest’s cache mode to
+  //    "no-store".
+  if (httpCache == null) {
+    httpRequest.cache = 'no-store'
+  }
+
+  //    24. If httpRequest’s cache mode is neither "no-store" nor "reload",
+  //    then:
+  if (httpRequest.mode !== 'no-store' && httpRequest.mode !== 'reload') {
+    // TODO: cache
+  }
+
+  // 9. If aborted, then return the appropriate network error for fetchParams.
+  // TODO
+
+  // 10. If response is null, then:
+  if (response == null) {
+    // 1. If httpRequest’s cache mode is "only-if-cached", then return a
+    // network error.
+    if (httpRequest.mode === 'only-if-cached') {
+      return makeNetworkError('only if cached')
+    }
+
+    // 2. Let forwardResponse be the result of running HTTP-network fetch
+    // given httpFetchParams, includeCredentials, and isNewConnectionFetch.
+    const forwardResponse = await httpNetworkFetch(
+      httpFetchParams,
+      includeCredentials,
+      isNewConnectionFetch
+    )
+
+    // 3. If httpRequest’s method is unsafe and forwardResponse’s status is
+    // in the range 200 to 399, inclusive, invalidate appropriate stored
+    // responses in httpCache, as per the "Invalidation" chapter of HTTP
+    // Caching, and set storedResponse to null. [HTTP-CACHING]
+    if (
+      !safeMethodsSet.has(httpRequest.method) &&
+      forwardResponse.status >= 200 &&
+      forwardResponse.status <= 399
+    ) {
+      // TODO: cache
+    }
+
+    // 4. If the revalidatingFlag is set and forwardResponse’s status is 304,
+    // then:
+    if (revalidatingFlag && forwardResponse.status === 304) {
+      // TODO: cache
+    }
+
+    // 5. If response is null, then:
+    if (response == null) {
+      // 1. Set response to forwardResponse.
+      response = forwardResponse
+
+      // 2. Store httpRequest and forwardResponse in httpCache, as per the
+      // "Storing Responses in Caches" chapter of HTTP Caching. [HTTP-CACHING]
+      // TODO: cache
+    }
+  }
+
+  // 11. Set response’s URL list to a clone of httpRequest’s URL list.
+  response.urlList = [...httpRequest.urlList]
+
+  // 12. If httpRequest’s header list contains `Range`, then set response’s
+  // range-requested flag.
+  if (httpRequest.headersList.contains('range')) {
+    response.rangeRequested = true
+  }
+
+  // 13. Set response’s request-includes-credentials to includeCredentials.
+  response.requestIncludesCredentials = includeCredentials
+
+  // 14. If response’s status is 401, httpRequest’s response tainting is not
+  // "cors", includeCredentials is true, and request’s window is an environment
+  // settings object, then:
+  // TODO
+
+  // 15. If response’s status is 407, then:
+  if (response.status === 407) {
+    // 1. If request’s window is "no-window", then return a network error.
+    if (request.window === 'no-window') {
+      return makeNetworkError()
+    }
+
+    // 2. ???
+
+    // 3. If fetchParams is canceled, then return the appropriate network error for fetchParams.
+    if (isCancelled(fetchParams)) {
+      return makeAppropriateNetworkError(fetchParams)
+    }
+
+    // 4. Prompt the end user as appropriate in request’s window and store
+    // the result as a proxy-authentication entry. [HTTP-AUTH]
+    // TODO: Invoke some kind of callback?
+
+    // 5. Set response to the result of running HTTP-network-or-cache fetch given
+    // fetchParams.
+    // TODO
+    return makeNetworkError('proxy authentication required')
+  }
+
+  // 16. If all of the following are true
+  if (
+    // response’s status is 421
+    response.status === 421 &&
+    // isNewConnectionFetch is false
+    !isNewConnectionFetch &&
+    // request’s body is null, or request’s body is non-null and request’s body’s source is non-null
+    (request.body == null || request.body.source != null)
+  ) {
+    // then:
+
+    // 1. If fetchParams is canceled, then return the appropriate network error for fetchParams.
+    if (isCancelled(fetchParams)) {
+      return makeAppropriateNetworkError(fetchParams)
+    }
+
+    // 2. Set response to the result of running HTTP-network-or-cache
+    // fetch given fetchParams, isAuthenticationFetch, and true.
+
+    // TODO (spec): The spec doesn't specify this but we need to cancel
+    // the active response before we can start a new one.
+    // https://github.com/whatwg/fetch/issues/1293
+    fetchParams.controller.connection.destroy()
+
+    response = await httpNetworkOrCacheFetch(
+      fetchParams,
+      isAuthenticationFetch,
+      true
+    )
+  }
+
+  // 17. If isAuthenticationFetch is true, then create an authentication entry
+  if (isAuthenticationFetch) {
+    // TODO
+  }
+
+  // 18. Return response.
+  return response
+}
+
+// https://fetch.spec.whatwg.org/#http-network-fetch
+async function httpNetworkFetch (
+  fetchParams,
+  includeCredentials = false,
+  forceNewConnection = false
+) {
+  assert(!fetchParams.controller.connection || fetchParams.controller.connection.destroyed)
+
+  fetchParams.controller.connection = {
+    abort: null,
+    destroyed: false,
+    destroy (err) {
+      if (!this.destroyed) {
+        this.destroyed = true
+        this.abort?.(err ?? new DOMException('The operation was aborted.', 'AbortError'))
+      }
+    }
+  }
+
+  // 1. Let request be fetchParams’s request.
+  const request = fetchParams.request
+
+  // 2. Let response be null.
+  let response = null
+
+  // 3. Let timingInfo be fetchParams’s timing info.
+  const timingInfo = fetchParams.timingInfo
+
+  // 4. Let httpCache be the result of determining the HTTP cache partition,
+  // given request.
+  // TODO: cache
+  const httpCache = null
+
+  // 5. If httpCache is null, then set request’s cache mode to "no-store".
+  if (httpCache == null) {
+    request.cache = 'no-store'
+  }
+
+  // 6. Let networkPartitionKey be the result of determining the network
+  // partition key given request.
+  // TODO
+
+  // 7. Let newConnection be "yes" if forceNewConnection is true; otherwise
+  // "no".
+  const newConnection = forceNewConnection ? 'yes' : 'no' // eslint-disable-line no-unused-vars
+
+  // 8. Switch on request’s mode:
+  if (request.mode === 'websocket') {
+    // Let connection be the result of obtaining a WebSocket connection,
+    // given request’s current URL.
+    // TODO
+  } else {
+    // Let connection be the result of obtaining a connection, given
+    // networkPartitionKey, request’s current URL’s origin,
+    // includeCredentials, and forceNewConnection.
+    // TODO
+  }
+
+  // 9. Run these steps, but abort when the ongoing fetch is terminated:
+
+  //    1. If connection is failure, then return a network error.
+
+  //    2. Set timingInfo’s final connection timing info to the result of
+  //    calling clamp and coarsen connection timing info with connection’s
+  //    timing info, timingInfo’s post-redirect start time, and fetchParams’s
+  //    cross-origin isolated capability.
+
+  //    3. If connection is not an HTTP/2 connection, request’s body is non-null,
+  //    and request’s body’s source is null, then append (`Transfer-Encoding`,
+  //    `chunked`) to request’s header list.
+
+  //    4. Set timingInfo’s final network-request start time to the coarsened
+  //    shared current time given fetchParams’s cross-origin isolated
+  //    capability.
+
+  //    5. Set response to the result of making an HTTP request over connection
+  //    using request with the following caveats:
+
+  //        - Follow the relevant requirements from HTTP. [HTTP] [HTTP-SEMANTICS]
+  //        [HTTP-COND] [HTTP-CACHING] [HTTP-AUTH]
+
+  //        - If request’s body is non-null, and request’s body’s source is null,
+  //        then the user agent may have a buffer of up to 64 kibibytes and store
+  //        a part of request’s body in that buffer. If the user agent reads from
+  //        request’s body beyond that buffer’s size and the user agent needs to
+  //        resend request, then instead return a network error.
+
+  //        - Set timingInfo’s final network-response start time to the coarsened
+  //        shared current time given fetchParams’s cross-origin isolated capability,
+  //        immediately after the user agent’s HTTP parser receives the first byte
+  //        of the response (e.g., frame header bytes for HTTP/2 or response status
+  //        line for HTTP/1.x).
+
+  //        - Wait until all the headers are transmitted.
+
+  //        - Any responses whose status is in the range 100 to 199, inclusive,
+  //        and is not 101, are to be ignored, except for the purposes of setting
+  //        timingInfo’s final network-response start time above.
+
+  //    - If request’s header list contains `Transfer-Encoding`/`chunked` and
+  //    response is transferred via HTTP/1.0 or older, then return a network
+  //    error.
+
+  //    - If the HTTP request results in a TLS client certificate dialog, then:
+
+  //        1. If request’s window is an environment settings object, make the
+  //        dialog available in request’s window.
+
+  //        2. Otherwise, return a network error.
+
+  // To transmit request’s body body, run these steps:
+  let requestBody = null
+  // 1. If body is null and fetchParams’s process request end-of-body is
+  // non-null, then queue a fetch task given fetchParams’s process request
+  // end-of-body and fetchParams’s task destination.
+  if (request.body == null && fetchParams.processRequestEndOfBody) {
+    queueMicrotask(() => fetchParams.processRequestEndOfBody())
+  } else if (request.body != null) {
+    // 2. Otherwise, if body is non-null:
+
+    //    1. Let processBodyChunk given bytes be these steps:
+    const processBodyChunk = async function * (bytes) {
+      // 1. If the ongoing fetch is terminated, then abort these steps.
+      if (isCancelled(fetchParams)) {
+        return
+      }
+
+      // 2. Run this step in parallel: transmit bytes.
+      yield bytes
+
+      // 3. If fetchParams’s process request body is non-null, then run
+      // fetchParams’s process request body given bytes’s length.
+      fetchParams.processRequestBodyChunkLength?.(bytes.byteLength)
+    }
+
+    // 2. Let processEndOfBody be these steps:
+    const processEndOfBody = () => {
+      // 1. If fetchParams is canceled, then abort these steps.
+      if (isCancelled(fetchParams)) {
+        return
+      }
+
+      // 2. If fetchParams’s process request end-of-body is non-null,
+      // then run fetchParams’s process request end-of-body.
+      if (fetchParams.processRequestEndOfBody) {
+        fetchParams.processRequestEndOfBody()
+      }
+    }
+
+    // 3. Let processBodyError given e be these steps:
+    const processBodyError = (e) => {
+      // 1. If fetchParams is canceled, then abort these steps.
+      if (isCancelled(fetchParams)) {
+        return
+      }
+
+      // 2. If e is an "AbortError" DOMException, then abort fetchParams’s controller.
+      if (e.name === 'AbortError') {
+        fetchParams.controller.abort()
+      } else {
+        fetchParams.controller.terminate(e)
+      }
+    }
+
+    // 4. Incrementally read request’s body given processBodyChunk, processEndOfBody,
+    // processBodyError, and fetchParams’s task destination.
+    requestBody = (async function * () {
+      try {
+        for await (const bytes of request.body.stream) {
+          yield * processBodyChunk(bytes)
+        }
+        processEndOfBody()
+      } catch (err) {
+        processBodyError(err)
+      }
+    })()
+  }
+
+  try {
+    // socket is only provided for websockets
+    const { body, status, statusText, headersList, socket } = await dispatch({ body: requestBody })
+
+    if (socket) {
+      response = makeResponse({ status, statusText, headersList, socket })
+    } else {
+      const iterator = body[Symbol.asyncIterator]()
+      fetchParams.controller.next = () => iterator.next()
+
+      response = makeResponse({ status, statusText, headersList })
+    }
+  } catch (err) {
+    // 10. If aborted, then:
+    if (err.name === 'AbortError') {
+      // 1. If connection uses HTTP/2, then transmit an RST_STREAM frame.
+      fetchParams.controller.connection.destroy()
+
+      // 2. Return the appropriate network error for fetchParams.
+      return makeAppropriateNetworkError(fetchParams, err)
+    }
+
+    return makeNetworkError(err)
+  }
+
+  // 11. Let pullAlgorithm be an action that resumes the ongoing fetch
+  // if it is suspended.
+  const pullAlgorithm = () => {
+    fetchParams.controller.resume()
+  }
+
+  // 12. Let cancelAlgorithm be an algorithm that aborts fetchParams’s
+  // controller with reason, given reason.
+  const cancelAlgorithm = (reason) => {
+    fetchParams.controller.abort(reason)
+  }
+
+  // 13. Let highWaterMark be a non-negative, non-NaN number, chosen by
+  // the user agent.
+  // TODO
+
+  // 14. Let sizeAlgorithm be an algorithm that accepts a chunk object
+  // and returns a non-negative, non-NaN, non-infinite number, chosen by the user agent.
+  // TODO
+
+  // 15. Let stream be a new ReadableStream.
+  // 16. Set up stream with pullAlgorithm set to pullAlgorithm,
+  // cancelAlgorithm set to cancelAlgorithm, highWaterMark set to
+  // highWaterMark, and sizeAlgorithm set to sizeAlgorithm.
+  if (!ReadableStream) {
+    ReadableStream = require('stream/web').ReadableStream
+  }
+
+  const stream = new ReadableStream(
+    {
+      async start (controller) {
+        fetchParams.controller.controller = controller
+      },
+      async pull (controller) {
+        await pullAlgorithm(controller)
+      },
+      async cancel (reason) {
+        await cancelAlgorithm(reason)
+      }
+    },
+    {
+      highWaterMark: 0,
+      size () {
+        return 1
+      }
+    }
+  )
+
+  // 17. Run these steps, but abort when the ongoing fetch is terminated:
+
+  //    1. Set response’s body to a new body whose stream is stream.
+  response.body = { stream }
+
+  //    2. If response is not a network error and request’s cache mode is
+  //    not "no-store", then update response in httpCache for request.
+  //    TODO
+
+  //    3. If includeCredentials is true and the user agent is not configured
+  //    to block cookies for request (see section 7 of [COOKIES]), then run the
+  //    "set-cookie-string" parsing algorithm (see section 5.2 of [COOKIES]) on
+  //    the value of each header whose name is a byte-case-insensitive match for
+  //    `Set-Cookie` in response’s header list, if any, and request’s current URL.
+  //    TODO
+
+  // 18. If aborted, then:
+  // TODO
+
+  // 19. Run these steps in parallel:
+
+  //    1. Run these steps, but abort when fetchParams is canceled:
+  fetchParams.controller.on('terminated', onAborted)
+  fetchParams.controller.resume = async () => {
+    // 1. While true
+    while (true) {
+      // 1-3. See onData...
+
+      // 4. Set bytes to the result of handling content codings given
+      // codings and bytes.
+      let bytes
+      let isFailure
+      try {
+        const { done, value } = await fetchParams.controller.next()
+
+        if (isAborted(fetchParams)) {
+          break
+        }
+
+        bytes = done ? undefined : value
+      } catch (err) {
+        if (fetchParams.controller.ended && !timingInfo.encodedBodySize) {
+          // zlib doesn't like empty streams.
+          bytes = undefined
+        } else {
+          bytes = err
+
+          // err may be propagated from the result of calling readablestream.cancel,
+          // which might not be an error. https://github.com/nodejs/undici/issues/2009
+          isFailure = true
+        }
+      }
+
+      if (bytes === undefined) {
+        // 2. Otherwise, if the bytes transmission for response’s message
+        // body is done normally and stream is readable, then close
+        // stream, finalize response for fetchParams and response, and
+        // abort these in-parallel steps.
+        readableStreamClose(fetchParams.controller.controller)
+
+        finalizeResponse(fetchParams, response)
+
+        return
+      }
+
+      // 5. Increase timingInfo’s decoded body size by bytes’s length.
+      timingInfo.decodedBodySize += bytes?.byteLength ?? 0
+
+      // 6. If bytes is failure, then terminate fetchParams’s controller.
+      if (isFailure) {
+        fetchParams.controller.terminate(bytes)
+        return
+      }
+
+      // 7. Enqueue a Uint8Array wrapping an ArrayBuffer containing bytes
+      // into stream.
+      fetchParams.controller.controller.enqueue(new Uint8Array(bytes))
+
+      // 8. If stream is errored, then terminate the ongoing fetch.
+      if (isErrored(stream)) {
+        fetchParams.controller.terminate()
+        return
+      }
+
+      // 9. If stream doesn’t need more data ask the user agent to suspend
+      // the ongoing fetch.
+      if (!fetchParams.controller.controller.desiredSize) {
+        return
+      }
+    }
+  }
+
+  //    2. If aborted, then:
+  function onAborted (reason) {
+    // 2. If fetchParams is aborted, then:
+    if (isAborted(fetchParams)) {
+      // 1. Set response’s aborted flag.
+      response.aborted = true
+
+      // 2. If stream is readable, then error stream with the result of
+      //    deserialize a serialized abort reason given fetchParams’s
+      //    controller’s serialized abort reason and an
+      //    implementation-defined realm.
+      if (isReadable(stream)) {
+        fetchParams.controller.controller.error(
+          fetchParams.controller.serializedAbortReason
+        )
+      }
+    } else {
+      // 3. Otherwise, if stream is readable, error stream with a TypeError.
+      if (isReadable(stream)) {
+        fetchParams.controller.controller.error(new TypeError('terminated', {
+          cause: isErrorLike(reason) ? reason : undefined
+        }))
+      }
+    }
+
+    // 4. If connection uses HTTP/2, then transmit an RST_STREAM frame.
+    // 5. Otherwise, the user agent should close connection unless it would be bad for performance to do so.
+    fetchParams.controller.connection.destroy()
+  }
+
+  // 20. Return response.
+  return response
+
+  async function dispatch ({ body }) {
+    const url = requestCurrentURL(request)
+    /** @type {import('../..').Agent} */
+    const agent = fetchParams.controller.dispatcher
+
+    return new Promise((resolve, reject) => agent.dispatch(
+      {
+        path: url.pathname + url.search,
+        origin: url.origin,
+        method: request.method,
+        body: fetchParams.controller.dispatcher.isMockActive ? request.body && (request.body.source || request.body.stream) : body,
+        headers: request.headersList.entries,
+        maxRedirections: 0,
+        upgrade: request.mode === 'websocket' ? 'websocket' : undefined
+      },
+      {
+        body: null,
+        abort: null,
+
+        onConnect (abort) {
+          // TODO (fix): Do we need connection here?
+          const { connection } = fetchParams.controller
+
+          if (connection.destroyed) {
+            abort(new DOMException('The operation was aborted.', 'AbortError'))
+          } else {
+            fetchParams.controller.on('terminated', abort)
+            this.abort = connection.abort = abort
+          }
+        },
+
+        onHeaders (status, headersList, resume, statusText) {
+          if (status < 200) {
+            return
+          }
+
+          let codings = []
+          let location = ''
+
+          const headers = new Headers()
+
+          // For H2, the headers are a plain JS object
+          // We distinguish between them and iterate accordingly
+          if (Array.isArray(headersList)) {
+            for (let n = 0; n < headersList.length; n += 2) {
+              const key = headersList[n + 0].toString('latin1')
+              const val = headersList[n + 1].toString('latin1')
+              if (key.toLowerCase() === 'content-encoding') {
+                // https://www.rfc-editor.org/rfc/rfc7231#section-3.1.2.1
+                // "All content-coding values are case-insensitive..."
+                codings = val.toLowerCase().split(',').map((x) => x.trim())
+              } else if (key.toLowerCase() === 'location') {
+                location = val
+              }
+
+              headers[kHeadersList].append(key, val)
+            }
+          } else {
+            const keys = Object.keys(headersList)
+            for (const key of keys) {
+              const val = headersList[key]
+              if (key.toLowerCase() === 'content-encoding') {
+                // https://www.rfc-editor.org/rfc/rfc7231#section-3.1.2.1
+                // "All content-coding values are case-insensitive..."
+                codings = val.toLowerCase().split(',').map((x) => x.trim()).reverse()
+              } else if (key.toLowerCase() === 'location') {
+                location = val
+              }
+
+              headers[kHeadersList].append(key, val)
+            }
+          }
+
+          this.body = new Readable({ read: resume })
+
+          const decoders = []
+
+          const willFollow = request.redirect === 'follow' &&
+            location &&
+            redirectStatusSet.has(status)
+
+          // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Encoding
+          if (request.method !== 'HEAD' && request.method !== 'CONNECT' && !nullBodyStatus.includes(status) && !willFollow) {
+            for (const coding of codings) {
+              // https://www.rfc-editor.org/rfc/rfc9112.html#section-7.2
+              if (coding === 'x-gzip' || coding === 'gzip') {
+                decoders.push(zlib.createGunzip({
+                  // Be less strict when decoding compressed responses, since sometimes
+                  // servers send slightly invalid responses that are still accepted
+                  // by common browsers.
+                  // Always using Z_SYNC_FLUSH is what cURL does.
+                  flush: zlib.constants.Z_SYNC_FLUSH,
+                  finishFlush: zlib.constants.Z_SYNC_FLUSH
+                }))
+              } else if (coding === 'deflate') {
+                decoders.push(zlib.createInflate())
+              } else if (coding === 'br') {
+                decoders.push(zlib.createBrotliDecompress())
+              } else {
+                decoders.length = 0
+                break
+              }
+            }
+          }
+
+          resolve({
+            status,
+            statusText,
+            headersList: headers[kHeadersList],
+            body: decoders.length
+              ? pipeline(this.body, ...decoders, () => { })
+              : this.body.on('error', () => {})
+          })
+
+          return true
+        },
+
+        onData (chunk) {
+          if (fetchParams.controller.dump) {
+            return
+          }
+
+          // 1. If one or more bytes have been transmitted from response’s
+          // message body, then:
+
+          //  1. Let bytes be the transmitted bytes.
+          const bytes = chunk
+
+          //  2. Let codings be the result of extracting header list values
+          //  given `Content-Encoding` and response’s header list.
+          //  See pullAlgorithm.
+
+          //  3. Increase timingInfo’s encoded body size by bytes’s length.
+          timingInfo.encodedBodySize += bytes.byteLength
+
+          //  4. See pullAlgorithm...
+
+          return this.body.push(bytes)
+        },
+
+        onComplete () {
+          if (this.abort) {
+            fetchParams.controller.off('terminated', this.abort)
+          }
+
+          fetchParams.controller.ended = true
+
+          this.body.push(null)
+        },
+
+        onError (error) {
+          if (this.abort) {
+            fetchParams.controller.off('terminated', this.abort)
+          }
+
+          this.body?.destroy(error)
+
+          fetchParams.controller.terminate(error)
+
+          reject(error)
+        },
+
+        onUpgrade (status, headersList, socket) {
+          if (status !== 101) {
+            return
+          }
+
+          const headers = new Headers()
+
+          for (let n = 0; n < headersList.length; n += 2) {
+            const key = headersList[n + 0].toString('latin1')
+            const val = headersList[n + 1].toString('latin1')
+
+            headers[kHeadersList].append(key, val)
+          }
+
+          resolve({
+            status,
+            statusText: STATUS_CODES[status],
+            headersList: headers[kHeadersList],
+            socket
+          })
+
+          return true
+        }
+      }
+    ))
+  }
+}
+
+module.exports = {
+  fetch,
+  Fetch,
+  fetching,
+  finalizeAndReportTiming
+}
diff --git a/lib/fetch/request.js b/lib/fetch/request.js
new file mode 100644
index 0000000..6fe4dff
--- /dev/null
+++ b/lib/fetch/request.js
@@ -0,0 +1,946 @@
+/* globals AbortController */
+
+'use strict'
+
+const { extractBody, mixinBody, cloneBody } = require('./body')
+const { Headers, fill: fillHeaders, HeadersList } = require('./headers')
+const { FinalizationRegistry } = require('../compat/dispatcher-weakref')()
+const util = require('../core/util')
+const {
+  isValidHTTPToken,
+  sameOrigin,
+  normalizeMethod,
+  makePolicyContainer,
+  normalizeMethodRecord
+} = require('./util')
+const {
+  forbiddenMethodsSet,
+  corsSafeListedMethodsSet,
+  referrerPolicy,
+  requestRedirect,
+  requestMode,
+  requestCredentials,
+  requestCache,
+  requestDuplex
+} = require('./constants')
+const { kEnumerableProperty } = util
+const { kHeaders, kSignal, kState, kGuard, kRealm } = require('./symbols')
+const { webidl } = require('./webidl')
+const { getGlobalOrigin } = require('./global')
+const { URLSerializer } = require('./dataURL')
+const { kHeadersList, kConstruct } = require('../core/symbols')
+const assert = require('assert')
+const { getMaxListeners, setMaxListeners, getEventListeners, defaultMaxListeners } = require('events')
+
+let TransformStream = globalThis.TransformStream
+
+const kAbortController = Symbol('abortController')
+
+const requestFinalizer = new FinalizationRegistry(({ signal, abort }) => {
+  signal.removeEventListener('abort', abort)
+})
+
+// https://fetch.spec.whatwg.org/#request-class
+class Request {
+  // https://fetch.spec.whatwg.org/#dom-request
+  constructor (input, init = {}) {
+    if (input === kConstruct) {
+      return
+    }
+
+    webidl.argumentLengthCheck(arguments, 1, { header: 'Request constructor' })
+
+    input = webidl.converters.RequestInfo(input)
+    init = webidl.converters.RequestInit(init)
+
+    // https://html.spec.whatwg.org/multipage/webappapis.html#environment-settings-object
+    this[kRealm] = {
+      settingsObject: {
+        baseUrl: getGlobalOrigin(),
+        get origin () {
+          return this.baseUrl?.origin
+        },
+        policyContainer: makePolicyContainer()
+      }
+    }
+
+    // 1. Let request be null.
+    let request = null
+
+    // 2. Let fallbackMode be null.
+    let fallbackMode = null
+
+    // 3. Let baseURL be this’s relevant settings object’s API base URL.
+    const baseUrl = this[kRealm].settingsObject.baseUrl
+
+    // 4. Let signal be null.
+    let signal = null
+
+    // 5. If input is a string, then:
+    if (typeof input === 'string') {
+      // 1. Let parsedURL be the result of parsing input with baseURL.
+      // 2. If parsedURL is failure, then throw a TypeError.
+      let parsedURL
+      try {
+        parsedURL = new URL(input, baseUrl)
+      } catch (err) {
+        throw new TypeError('Failed to parse URL from ' + input, { cause: err })
+      }
+
+      // 3. If parsedURL includes credentials, then throw a TypeError.
+      if (parsedURL.username || parsedURL.password) {
+        throw new TypeError(
+          'Request cannot be constructed from a URL that includes credentials: ' +
+            input
+        )
+      }
+
+      // 4. Set request to a new request whose URL is parsedURL.
+      request = makeRequest({ urlList: [parsedURL] })
+
+      // 5. Set fallbackMode to "cors".
+      fallbackMode = 'cors'
+    } else {
+      // 6. Otherwise:
+
+      // 7. Assert: input is a Request object.
+      assert(input instanceof Request)
+
+      // 8. Set request to input’s request.
+      request = input[kState]
+
+      // 9. Set signal to input’s signal.
+      signal = input[kSignal]
+    }
+
+    // 7. Let origin be this’s relevant settings object’s origin.
+    const origin = this[kRealm].settingsObject.origin
+
+    // 8. Let window be "client".
+    let window = 'client'
+
+    // 9. If request’s window is an environment settings object and its origin
+    // is same origin with origin, then set window to request’s window.
+    if (
+      request.window?.constructor?.name === 'EnvironmentSettingsObject' &&
+      sameOrigin(request.window, origin)
+    ) {
+      window = request.window
+    }
+
+    // 10. If init["window"] exists and is non-null, then throw a TypeError.
+    if (init.window != null) {
+      throw new TypeError(`'window' option '${window}' must be null`)
+    }
+
+    // 11. If init["window"] exists, then set window to "no-window".
+    if ('window' in init) {
+      window = 'no-window'
+    }
+
+    // 12. Set request to a new request with the following properties:
+    request = makeRequest({
+      // URL request’s URL.
+      // undici implementation note: this is set as the first item in request's urlList in makeRequest
+      // method request’s method.
+      method: request.method,
+      // header list A copy of request’s header list.
+      // undici implementation note: headersList is cloned in makeRequest
+      headersList: request.headersList,
+      // unsafe-request flag Set.
+      unsafeRequest: request.unsafeRequest,
+      // client This’s relevant settings object.
+      client: this[kRealm].settingsObject,
+      // window window.
+      window,
+      // priority request’s priority.
+      priority: request.priority,
+      // origin request’s origin. The propagation of the origin is only significant for navigation requests
+      // being handled by a service worker. In this scenario a request can have an origin that is different
+      // from the current client.
+      origin: request.origin,
+      // referrer request’s referrer.
+      referrer: request.referrer,
+      // referrer policy request’s referrer policy.
+      referrerPolicy: request.referrerPolicy,
+      // mode request’s mode.
+      mode: request.mode,
+      // credentials mode request’s credentials mode.
+      credentials: request.credentials,
+      // cache mode request’s cache mode.
+      cache: request.cache,
+      // redirect mode request’s redirect mode.
+      redirect: request.redirect,
+      // integrity metadata request’s integrity metadata.
+      integrity: request.integrity,
+      // keepalive request’s keepalive.
+      keepalive: request.keepalive,
+      // reload-navigation flag request’s reload-navigation flag.
+      reloadNavigation: request.reloadNavigation,
+      // history-navigation flag request’s history-navigation flag.
+      historyNavigation: request.historyNavigation,
+      // URL list A clone of request’s URL list.
+      urlList: [...request.urlList]
+    })
+
+    const initHasKey = Object.keys(init).length !== 0
+
+    // 13. If init is not empty, then:
+    if (initHasKey) {
+      // 1. If request’s mode is "navigate", then set it to "same-origin".
+      if (request.mode === 'navigate') {
+        request.mode = 'same-origin'
+      }
+
+      // 2. Unset request’s reload-navigation flag.
+      request.reloadNavigation = false
+
+      // 3. Unset request’s history-navigation flag.
+      request.historyNavigation = false
+
+      // 4. Set request’s origin to "client".
+      request.origin = 'client'
+
+      // 5. Set request’s referrer to "client"
+      request.referrer = 'client'
+
+      // 6. Set request’s referrer policy to the empty string.
+      request.referrerPolicy = ''
+
+      // 7. Set request’s URL to request’s current URL.
+      request.url = request.urlList[request.urlList.length - 1]
+
+      // 8. Set request’s URL list to « request’s URL ».
+      request.urlList = [request.url]
+    }
+
+    // 14. If init["referrer"] exists, then:
+    if (init.referrer !== undefined) {
+      // 1. Let referrer be init["referrer"].
+      const referrer = init.referrer
+
+      // 2. If referrer is the empty string, then set request’s referrer to "no-referrer".
+      if (referrer === '') {
+        request.referrer = 'no-referrer'
+      } else {
+        // 1. Let parsedReferrer be the result of parsing referrer with
+        // baseURL.
+        // 2. If parsedReferrer is failure, then throw a TypeError.
+        let parsedReferrer
+        try {
+          parsedReferrer = new URL(referrer, baseUrl)
+        } catch (err) {
+          throw new TypeError(`Referrer "${referrer}" is not a valid URL.`, { cause: err })
+        }
+
+        // 3. If one of the following is true
+        // - parsedReferrer’s scheme is "about" and path is the string "client"
+        // - parsedReferrer’s origin is not same origin with origin
+        // then set request’s referrer to "client".
+        if (
+          (parsedReferrer.protocol === 'about:' && parsedReferrer.hostname === 'client') ||
+          (origin && !sameOrigin(parsedReferrer, this[kRealm].settingsObject.baseUrl))
+        ) {
+          request.referrer = 'client'
+        } else {
+          // 4. Otherwise, set request’s referrer to parsedReferrer.
+          request.referrer = parsedReferrer
+        }
+      }
+    }
+
+    // 15. If init["referrerPolicy"] exists, then set request’s referrer policy
+    // to it.
+    if (init.referrerPolicy !== undefined) {
+      request.referrerPolicy = init.referrerPolicy
+    }
+
+    // 16. Let mode be init["mode"] if it exists, and fallbackMode otherwise.
+    let mode
+    if (init.mode !== undefined) {
+      mode = init.mode
+    } else {
+      mode = fallbackMode
+    }
+
+    // 17. If mode is "navigate", then throw a TypeError.
+    if (mode === 'navigate') {
+      throw webidl.errors.exception({
+        header: 'Request constructor',
+        message: 'invalid request mode navigate.'
+      })
+    }
+
+    // 18. If mode is non-null, set request’s mode to mode.
+    if (mode != null) {
+      request.mode = mode
+    }
+
+    // 19. If init["credentials"] exists, then set request’s credentials mode
+    // to it.
+    if (init.credentials !== undefined) {
+      request.credentials = init.credentials
+    }
+
+    // 18. If init["cache"] exists, then set request’s cache mode to it.
+    if (init.cache !== undefined) {
+      request.cache = init.cache
+    }
+
+    // 21. If request’s cache mode is "only-if-cached" and request’s mode is
+    // not "same-origin", then throw a TypeError.
+    if (request.cache === 'only-if-cached' && request.mode !== 'same-origin') {
+      throw new TypeError(
+        "'only-if-cached' can be set only with 'same-origin' mode"
+      )
+    }
+
+    // 22. If init["redirect"] exists, then set request’s redirect mode to it.
+    if (init.redirect !== undefined) {
+      request.redirect = init.redirect
+    }
+
+    // 23. If init["integrity"] exists, then set request’s integrity metadata to it.
+    if (init.integrity != null) {
+      request.integrity = String(init.integrity)
+    }
+
+    // 24. If init["keepalive"] exists, then set request’s keepalive to it.
+    if (init.keepalive !== undefined) {
+      request.keepalive = Boolean(init.keepalive)
+    }
+
+    // 25. If init["method"] exists, then:
+    if (init.method !== undefined) {
+      // 1. Let method be init["method"].
+      let method = init.method
+
+      // 2. If method is not a method or method is a forbidden method, then
+      // throw a TypeError.
+      if (!isValidHTTPToken(method)) {
+        throw new TypeError(`'${method}' is not a valid HTTP method.`)
+      }
+
+      if (forbiddenMethodsSet.has(method.toUpperCase())) {
+        throw new TypeError(`'${method}' HTTP method is unsupported.`)
+      }
+
+      // 3. Normalize method.
+      method = normalizeMethodRecord[method] ?? normalizeMethod(method)
+
+      // 4. Set request’s method to method.
+      request.method = method
+    }
+
+    // 26. If init["signal"] exists, then set signal to it.
+    if (init.signal !== undefined) {
+      signal = init.signal
+    }
+
+    // 27. Set this’s request to request.
+    this[kState] = request
+
+    // 28. Set this’s signal to a new AbortSignal object with this’s relevant
+    // Realm.
+    // TODO: could this be simplified with AbortSignal.any
+    // (https://dom.spec.whatwg.org/#dom-abortsignal-any)
+    const ac = new AbortController()
+    this[kSignal] = ac.signal
+    this[kSignal][kRealm] = this[kRealm]
+
+    // 29. If signal is not null, then make this’s signal follow signal.
+    if (signal != null) {
+      if (
+        !signal ||
+        typeof signal.aborted !== 'boolean' ||
+        typeof signal.addEventListener !== 'function'
+      ) {
+        throw new TypeError(
+          "Failed to construct 'Request': member signal is not of type AbortSignal."
+        )
+      }
+
+      if (signal.aborted) {
+        ac.abort(signal.reason)
+      } else {
+        // Keep a strong ref to ac while request object
+        // is alive. This is needed to prevent AbortController
+        // from being prematurely garbage collected.
+        // See, https://github.com/nodejs/undici/issues/1926.
+        this[kAbortController] = ac
+
+        const acRef = new WeakRef(ac)
+        const abort = function () {
+          const ac = acRef.deref()
+          if (ac !== undefined) {
+            ac.abort(this.reason)
+          }
+        }
+
+        // Third-party AbortControllers may not work with these.
+        // See, https://github.com/nodejs/undici/pull/1910#issuecomment-1464495619.
+        try {
+          // If the max amount of listeners is equal to the default, increase it
+          // This is only available in node >= v19.9.0
+          if (typeof getMaxListeners === 'function' && getMaxListeners(signal) === defaultMaxListeners) {
+            setMaxListeners(100, signal)
+          } else if (getEventListeners(signal, 'abort').length >= defaultMaxListeners) {
+            setMaxListeners(100, signal)
+          }
+        } catch {}
+
+        util.addAbortListener(signal, abort)
+        requestFinalizer.register(ac, { signal, abort })
+      }
+    }
+
+    // 30. Set this’s headers to a new Headers object with this’s relevant
+    // Realm, whose header list is request’s header list and guard is
+    // "request".
+    this[kHeaders] = new Headers(kConstruct)
+    this[kHeaders][kHeadersList] = request.headersList
+    this[kHeaders][kGuard] = 'request'
+    this[kHeaders][kRealm] = this[kRealm]
+
+    // 31. If this’s request’s mode is "no-cors", then:
+    if (mode === 'no-cors') {
+      // 1. If this’s request’s method is not a CORS-safelisted method,
+      // then throw a TypeError.
+      if (!corsSafeListedMethodsSet.has(request.method)) {
+        throw new TypeError(
+          `'${request.method} is unsupported in no-cors mode.`
+        )
+      }
+
+      // 2. Set this’s headers’s guard to "request-no-cors".
+      this[kHeaders][kGuard] = 'request-no-cors'
+    }
+
+    // 32. If init is not empty, then:
+    if (initHasKey) {
+      /** @type {HeadersList} */
+      const headersList = this[kHeaders][kHeadersList]
+      // 1. Let headers be a copy of this’s headers and its associated header
+      // list.
+      // 2. If init["headers"] exists, then set headers to init["headers"].
+      const headers = init.headers !== undefined ? init.headers : new HeadersList(headersList)
+
+      // 3. Empty this’s headers’s header list.
+      headersList.clear()
+
+      // 4. If headers is a Headers object, then for each header in its header
+      // list, append header’s name/header’s value to this’s headers.
+      if (headers instanceof HeadersList) {
+        for (const [key, val] of headers) {
+          headersList.append(key, val)
+        }
+        // Note: Copy the `set-cookie` meta-data.
+        headersList.cookies = headers.cookies
+      } else {
+        // 5. Otherwise, fill this’s headers with headers.
+        fillHeaders(this[kHeaders], headers)
+      }
+    }
+
+    // 33. Let inputBody be input’s request’s body if input is a Request
+    // object; otherwise null.
+    const inputBody = input instanceof Request ? input[kState].body : null
+
+    // 34. If either init["body"] exists and is non-null or inputBody is
+    // non-null, and request’s method is `GET` or `HEAD`, then throw a
+    // TypeError.
+    if (
+      (init.body != null || inputBody != null) &&
+      (request.method === 'GET' || request.method === 'HEAD')
+    ) {
+      throw new TypeError('Request with GET/HEAD method cannot have body.')
+    }
+
+    // 35. Let initBody be null.
+    let initBody = null
+
+    // 36. If init["body"] exists and is non-null, then:
+    if (init.body != null) {
+      // 1. Let Content-Type be null.
+      // 2. Set initBody and Content-Type to the result of extracting
+      // init["body"], with keepalive set to request’s keepalive.
+      const [extractedBody, contentType] = extractBody(
+        init.body,
+        request.keepalive
+      )
+      initBody = extractedBody
+
+      // 3, If Content-Type is non-null and this’s headers’s header list does
+      // not contain `Content-Type`, then append `Content-Type`/Content-Type to
+      // this’s headers.
+      if (contentType && !this[kHeaders][kHeadersList].contains('content-type')) {
+        this[kHeaders].append('content-type', contentType)
+      }
+    }
+
+    // 37. Let inputOrInitBody be initBody if it is non-null; otherwise
+    // inputBody.
+    const inputOrInitBody = initBody ?? inputBody
+
+    // 38. If inputOrInitBody is non-null and inputOrInitBody’s source is
+    // null, then:
+    if (inputOrInitBody != null && inputOrInitBody.source == null) {
+      // 1. If initBody is non-null and init["duplex"] does not exist,
+      //    then throw a TypeError.
+      if (initBody != null && init.duplex == null) {
+        throw new TypeError('RequestInit: duplex option is required when sending a body.')
+      }
+
+      // 2. If this’s request’s mode is neither "same-origin" nor "cors",
+      // then throw a TypeError.
+      if (request.mode !== 'same-origin' && request.mode !== 'cors') {
+        throw new TypeError(
+          'If request is made from ReadableStream, mode should be "same-origin" or "cors"'
+        )
+      }
+
+      // 3. Set this’s request’s use-CORS-preflight flag.
+      request.useCORSPreflightFlag = true
+    }
+
+    // 39. Let finalBody be inputOrInitBody.
+    let finalBody = inputOrInitBody
+
+    // 40. If initBody is null and inputBody is non-null, then:
+    if (initBody == null && inputBody != null) {
+      // 1. If input is unusable, then throw a TypeError.
+      if (util.isDisturbed(inputBody.stream) || inputBody.stream.locked) {
+        throw new TypeError(
+          'Cannot construct a Request with a Request object that has already been used.'
+        )
+      }
+
+      // 2. Set finalBody to the result of creating a proxy for inputBody.
+      if (!TransformStream) {
+        TransformStream = require('stream/web').TransformStream
+      }
+
+      // https://streams.spec.whatwg.org/#readablestream-create-a-proxy
+      const identityTransform = new TransformStream()
+      inputBody.stream.pipeThrough(identityTransform)
+      finalBody = {
+        source: inputBody.source,
+        length: inputBody.length,
+        stream: identityTransform.readable
+      }
+    }
+
+    // 41. Set this’s request’s body to finalBody.
+    this[kState].body = finalBody
+  }
+
+  // Returns request’s HTTP method, which is "GET" by default.
+  get method () {
+    webidl.brandCheck(this, Request)
+
+    // The method getter steps are to return this’s request’s method.
+    return this[kState].method
+  }
+
+  // Returns the URL of request as a string.
+  get url () {
+    webidl.brandCheck(this, Request)
+
+    // The url getter steps are to return this’s request’s URL, serialized.
+    return URLSerializer(this[kState].url)
+  }
+
+  // Returns a Headers object consisting of the headers associated with request.
+  // Note that headers added in the network layer by the user agent will not
+  // be accounted for in this object, e.g., the "Host" header.
+  get headers () {
+    webidl.brandCheck(this, Request)
+
+    // The headers getter steps are to return this’s headers.
+    return this[kHeaders]
+  }
+
+  // Returns the kind of resource requested by request, e.g., "document"
+  // or "script".
+  get destination () {
+    webidl.brandCheck(this, Request)
+
+    // The destination getter are to return this’s request’s destination.
+    return this[kState].destination
+  }
+
+  // Returns the referrer of request. Its value can be a same-origin URL if
+  // explicitly set in init, the empty string to indicate no referrer, and
+  // "about:client" when defaulting to the global’s default. This is used
+  // during fetching to determine the value of the `Referer` header of the
+  // request being made.
+  get referrer () {
+    webidl.brandCheck(this, Request)
+
+    // 1. If this’s request’s referrer is "no-referrer", then return the
+    // empty string.
+    if (this[kState].referrer === 'no-referrer') {
+      return ''
+    }
+
+    // 2. If this’s request’s referrer is "client", then return
+    // "about:client".
+    if (this[kState].referrer === 'client') {
+      return 'about:client'
+    }
+
+    // Return this’s request’s referrer, serialized.
+    return this[kState].referrer.toString()
+  }
+
+  // Returns the referrer policy associated with request.
+  // This is used during fetching to compute the value of the request’s
+  // referrer.
+  get referrerPolicy () {
+    webidl.brandCheck(this, Request)
+
+    // The referrerPolicy getter steps are to return this’s request’s referrer policy.
+    return this[kState].referrerPolicy
+  }
+
+  // Returns the mode associated with request, which is a string indicating
+  // whether the request will use CORS, or will be restricted to same-origin
+  // URLs.
+  get mode () {
+    webidl.brandCheck(this, Request)
+
+    // The mode getter steps are to return this’s request’s mode.
+    return this[kState].mode
+  }
+
+  // Returns the credentials mode associated with request,
+  // which is a string indicating whether credentials will be sent with the
+  // request always, never, or only when sent to a same-origin URL.
+  get credentials () {
+    // The credentials getter steps are to return this’s request’s credentials mode.
+    return this[kState].credentials
+  }
+
+  // Returns the cache mode associated with request,
+  // which is a string indicating how the request will
+  // interact with the browser’s cache when fetching.
+  get cache () {
+    webidl.brandCheck(this, Request)
+
+    // The cache getter steps are to return this’s request’s cache mode.
+    return this[kState].cache
+  }
+
+  // Returns the redirect mode associated with request,
+  // which is a string indicating how redirects for the
+  // request will be handled during fetching. A request
+  // will follow redirects by default.
+  get redirect () {
+    webidl.brandCheck(this, Request)
+
+    // The redirect getter steps are to return this’s request’s redirect mode.
+    return this[kState].redirect
+  }
+
+  // Returns request’s subresource integrity metadata, which is a
+  // cryptographic hash of the resource being fetched. Its value
+  // consists of multiple hashes separated by whitespace. [SRI]
+  get integrity () {
+    webidl.brandCheck(this, Request)
+
+    // The integrity getter steps are to return this’s request’s integrity
+    // metadata.
+    return this[kState].integrity
+  }
+
+  // Returns a boolean indicating whether or not request can outlive the
+  // global in which it was created.
+  get keepalive () {
+    webidl.brandCheck(this, Request)
+
+    // The keepalive getter steps are to return this’s request’s keepalive.
+    return this[kState].keepalive
+  }
+
+  // Returns a boolean indicating whether or not request is for a reload
+  // navigation.
+  get isReloadNavigation () {
+    webidl.brandCheck(this, Request)
+
+    // The isReloadNavigation getter steps are to return true if this’s
+    // request’s reload-navigation flag is set; otherwise false.
+    return this[kState].reloadNavigation
+  }
+
+  // Returns a boolean indicating whether or not request is for a history
+  // navigation (a.k.a. back-foward navigation).
+  get isHistoryNavigation () {
+    webidl.brandCheck(this, Request)
+
+    // The isHistoryNavigation getter steps are to return true if this’s request’s
+    // history-navigation flag is set; otherwise false.
+    return this[kState].historyNavigation
+  }
+
+  // Returns the signal associated with request, which is an AbortSignal
+  // object indicating whether or not request has been aborted, and its
+  // abort event handler.
+  get signal () {
+    webidl.brandCheck(this, Request)
+
+    // The signal getter steps are to return this’s signal.
+    return this[kSignal]
+  }
+
+  get body () {
+    webidl.brandCheck(this, Request)
+
+    return this[kState].body ? this[kState].body.stream : null
+  }
+
+  get bodyUsed () {
+    webidl.brandCheck(this, Request)
+
+    return !!this[kState].body && util.isDisturbed(this[kState].body.stream)
+  }
+
+  get duplex () {
+    webidl.brandCheck(this, Request)
+
+    return 'half'
+  }
+
+  // Returns a clone of request.
+  clone () {
+    webidl.brandCheck(this, Request)
+
+    // 1. If this is unusable, then throw a TypeError.
+    if (this.bodyUsed || this.body?.locked) {
+      throw new TypeError('unusable')
+    }
+
+    // 2. Let clonedRequest be the result of cloning this’s request.
+    const clonedRequest = cloneRequest(this[kState])
+
+    // 3. Let clonedRequestObject be the result of creating a Request object,
+    // given clonedRequest, this’s headers’s guard, and this’s relevant Realm.
+    const clonedRequestObject = new Request(kConstruct)
+    clonedRequestObject[kState] = clonedRequest
+    clonedRequestObject[kRealm] = this[kRealm]
+    clonedRequestObject[kHeaders] = new Headers(kConstruct)
+    clonedRequestObject[kHeaders][kHeadersList] = clonedRequest.headersList
+    clonedRequestObject[kHeaders][kGuard] = this[kHeaders][kGuard]
+    clonedRequestObject[kHeaders][kRealm] = this[kHeaders][kRealm]
+
+    // 4. Make clonedRequestObject’s signal follow this’s signal.
+    const ac = new AbortController()
+    if (this.signal.aborted) {
+      ac.abort(this.signal.reason)
+    } else {
+      util.addAbortListener(
+        this.signal,
+        () => {
+          ac.abort(this.signal.reason)
+        }
+      )
+    }
+    clonedRequestObject[kSignal] = ac.signal
+
+    // 4. Return clonedRequestObject.
+    return clonedRequestObject
+  }
+}
+
+mixinBody(Request)
+
+function makeRequest (init) {
+  // https://fetch.spec.whatwg.org/#requests
+  const request = {
+    method: 'GET',
+    localURLsOnly: false,
+    unsafeRequest: false,
+    body: null,
+    client: null,
+    reservedClient: null,
+    replacesClientId: '',
+    window: 'client',
+    keepalive: false,
+    serviceWorkers: 'all',
+    initiator: '',
+    destination: '',
+    priority: null,
+    origin: 'client',
+    policyContainer: 'client',
+    referrer: 'client',
+    referrerPolicy: '',
+    mode: 'no-cors',
+    useCORSPreflightFlag: false,
+    credentials: 'same-origin',
+    useCredentials: false,
+    cache: 'default',
+    redirect: 'follow',
+    integrity: '',
+    cryptoGraphicsNonceMetadata: '',
+    parserMetadata: '',
+    reloadNavigation: false,
+    historyNavigation: false,
+    userActivation: false,
+    taintedOrigin: false,
+    redirectCount: 0,
+    responseTainting: 'basic',
+    preventNoCacheCacheControlHeaderModification: false,
+    done: false,
+    timingAllowFailed: false,
+    ...init,
+    headersList: init.headersList
+      ? new HeadersList(init.headersList)
+      : new HeadersList()
+  }
+  request.url = request.urlList[0]
+  return request
+}
+
+// https://fetch.spec.whatwg.org/#concept-request-clone
+function cloneRequest (request) {
+  // To clone a request request, run these steps:
+
+  // 1. Let newRequest be a copy of request, except for its body.
+  const newRequest = makeRequest({ ...request, body: null })
+
+  // 2. If request’s body is non-null, set newRequest’s body to the
+  // result of cloning request’s body.
+  if (request.body != null) {
+    newRequest.body = cloneBody(request.body)
+  }
+
+  // 3. Return newRequest.
+  return newRequest
+}
+
+Object.defineProperties(Request.prototype, {
+  method: kEnumerableProperty,
+  url: kEnumerableProperty,
+  headers: kEnumerableProperty,
+  redirect: kEnumerableProperty,
+  clone: kEnumerableProperty,
+  signal: kEnumerableProperty,
+  duplex: kEnumerableProperty,
+  destination: kEnumerableProperty,
+  body: kEnumerableProperty,
+  bodyUsed: kEnumerableProperty,
+  isHistoryNavigation: kEnumerableProperty,
+  isReloadNavigation: kEnumerableProperty,
+  keepalive: kEnumerableProperty,
+  integrity: kEnumerableProperty,
+  cache: kEnumerableProperty,
+  credentials: kEnumerableProperty,
+  attribute: kEnumerableProperty,
+  referrerPolicy: kEnumerableProperty,
+  referrer: kEnumerableProperty,
+  mode: kEnumerableProperty,
+  [Symbol.toStringTag]: {
+    value: 'Request',
+    configurable: true
+  }
+})
+
+webidl.converters.Request = webidl.interfaceConverter(
+  Request
+)
+
+// https://fetch.spec.whatwg.org/#requestinfo
+webidl.converters.RequestInfo = function (V) {
+  if (typeof V === 'string') {
+    return webidl.converters.USVString(V)
+  }
+
+  if (V instanceof Request) {
+    return webidl.converters.Request(V)
+  }
+
+  return webidl.converters.USVString(V)
+}
+
+webidl.converters.AbortSignal = webidl.interfaceConverter(
+  AbortSignal
+)
+
+// https://fetch.spec.whatwg.org/#requestinit
+webidl.converters.RequestInit = webidl.dictionaryConverter([
+  {
+    key: 'method',
+    converter: webidl.converters.ByteString
+  },
+  {
+    key: 'headers',
+    converter: webidl.converters.HeadersInit
+  },
+  {
+    key: 'body',
+    converter: webidl.nullableConverter(
+      webidl.converters.BodyInit
+    )
+  },
+  {
+    key: 'referrer',
+    converter: webidl.converters.USVString
+  },
+  {
+    key: 'referrerPolicy',
+    converter: webidl.converters.DOMString,
+    // https://w3c.github.io/webappsec-referrer-policy/#referrer-policy
+    allowedValues: referrerPolicy
+  },
+  {
+    key: 'mode',
+    converter: webidl.converters.DOMString,
+    // https://fetch.spec.whatwg.org/#concept-request-mode
+    allowedValues: requestMode
+  },
+  {
+    key: 'credentials',
+    converter: webidl.converters.DOMString,
+    // https://fetch.spec.whatwg.org/#requestcredentials
+    allowedValues: requestCredentials
+  },
+  {
+    key: 'cache',
+    converter: webidl.converters.DOMString,
+    // https://fetch.spec.whatwg.org/#requestcache
+    allowedValues: requestCache
+  },
+  {
+    key: 'redirect',
+    converter: webidl.converters.DOMString,
+    // https://fetch.spec.whatwg.org/#requestredirect
+    allowedValues: requestRedirect
+  },
+  {
+    key: 'integrity',
+    converter: webidl.converters.DOMString
+  },
+  {
+    key: 'keepalive',
+    converter: webidl.converters.boolean
+  },
+  {
+    key: 'signal',
+    converter: webidl.nullableConverter(
+      (signal) => webidl.converters.AbortSignal(
+        signal,
+        { strict: false }
+      )
+    )
+  },
+  {
+    key: 'window',
+    converter: webidl.converters.any
+  },
+  {
+    key: 'duplex',
+    converter: webidl.converters.DOMString,
+    allowedValues: requestDuplex
+  }
+])
+
+module.exports = { Request, makeRequest }
diff --git a/lib/fetch/response.js b/lib/fetch/response.js
new file mode 100644
index 0000000..7338612
--- /dev/null
+++ b/lib/fetch/response.js
@@ -0,0 +1,571 @@
+'use strict'
+
+const { Headers, HeadersList, fill } = require('./headers')
+const { extractBody, cloneBody, mixinBody } = require('./body')
+const util = require('../core/util')
+const { kEnumerableProperty } = util
+const {
+  isValidReasonPhrase,
+  isCancelled,
+  isAborted,
+  isBlobLike,
+  serializeJavascriptValueToJSONString,
+  isErrorLike,
+  isomorphicEncode
+} = require('./util')
+const {
+  redirectStatusSet,
+  nullBodyStatus,
+  DOMException
+} = require('./constants')
+const { kState, kHeaders, kGuard, kRealm } = require('./symbols')
+const { webidl } = require('./webidl')
+const { FormData } = require('./formdata')
+const { getGlobalOrigin } = require('./global')
+const { URLSerializer } = require('./dataURL')
+const { kHeadersList, kConstruct } = require('../core/symbols')
+const assert = require('assert')
+const { types } = require('util')
+
+const ReadableStream = globalThis.ReadableStream || require('stream/web').ReadableStream
+const textEncoder = new TextEncoder('utf-8')
+
+// https://fetch.spec.whatwg.org/#response-class
+class Response {
+  // Creates network error Response.
+  static error () {
+    // TODO
+    const relevantRealm = { settingsObject: {} }
+
+    // The static error() method steps are to return the result of creating a
+    // Response object, given a new network error, "immutable", and this’s
+    // relevant Realm.
+    const responseObject = new Response()
+    responseObject[kState] = makeNetworkError()
+    responseObject[kRealm] = relevantRealm
+    responseObject[kHeaders][kHeadersList] = responseObject[kState].headersList
+    responseObject[kHeaders][kGuard] = 'immutable'
+    responseObject[kHeaders][kRealm] = relevantRealm
+    return responseObject
+  }
+
+  // https://fetch.spec.whatwg.org/#dom-response-json
+  static json (data, init = {}) {
+    webidl.argumentLengthCheck(arguments, 1, { header: 'Response.json' })
+
+    if (init !== null) {
+      init = webidl.converters.ResponseInit(init)
+    }
+
+    // 1. Let bytes the result of running serialize a JavaScript value to JSON bytes on data.
+    const bytes = textEncoder.encode(
+      serializeJavascriptValueToJSONString(data)
+    )
+
+    // 2. Let body be the result of extracting bytes.
+    const body = extractBody(bytes)
+
+    // 3. Let responseObject be the result of creating a Response object, given a new response,
+    //    "response", and this’s relevant Realm.
+    const relevantRealm = { settingsObject: {} }
+    const responseObject = new Response()
+    responseObject[kRealm] = relevantRealm
+    responseObject[kHeaders][kGuard] = 'response'
+    responseObject[kHeaders][kRealm] = relevantRealm
+
+    // 4. Perform initialize a response given responseObject, init, and (body, "application/json").
+    initializeResponse(responseObject, init, { body: body[0], type: 'application/json' })
+
+    // 5. Return responseObject.
+    return responseObject
+  }
+
+  // Creates a redirect Response that redirects to url with status status.
+  static redirect (url, status = 302) {
+    const relevantRealm = { settingsObject: {} }
+
+    webidl.argumentLengthCheck(arguments, 1, { header: 'Response.redirect' })
+
+    url = webidl.converters.USVString(url)
+    status = webidl.converters['unsigned short'](status)
+
+    // 1. Let parsedURL be the result of parsing url with current settings
+    // object’s API base URL.
+    // 2. If parsedURL is failure, then throw a TypeError.
+    // TODO: base-URL?
+    let parsedURL
+    try {
+      parsedURL = new URL(url, getGlobalOrigin())
+    } catch (err) {
+      throw Object.assign(new TypeError('Failed to parse URL from ' + url), {
+        cause: err
+      })
+    }
+
+    // 3. If status is not a redirect status, then throw a RangeError.
+    if (!redirectStatusSet.has(status)) {
+      throw new RangeError('Invalid status code ' + status)
+    }
+
+    // 4. Let responseObject be the result of creating a Response object,
+    // given a new response, "immutable", and this’s relevant Realm.
+    const responseObject = new Response()
+    responseObject[kRealm] = relevantRealm
+    responseObject[kHeaders][kGuard] = 'immutable'
+    responseObject[kHeaders][kRealm] = relevantRealm
+
+    // 5. Set responseObject’s response’s status to status.
+    responseObject[kState].status = status
+
+    // 6. Let value be parsedURL, serialized and isomorphic encoded.
+    const value = isomorphicEncode(URLSerializer(parsedURL))
+
+    // 7. Append `Location`/value to responseObject’s response’s header list.
+    responseObject[kState].headersList.append('location', value)
+
+    // 8. Return responseObject.
+    return responseObject
+  }
+
+  // https://fetch.spec.whatwg.org/#dom-response
+  constructor (body = null, init = {}) {
+    if (body !== null) {
+      body = webidl.converters.BodyInit(body)
+    }
+
+    init = webidl.converters.ResponseInit(init)
+
+    // TODO
+    this[kRealm] = { settingsObject: {} }
+
+    // 1. Set this’s response to a new response.
+    this[kState] = makeResponse({})
+
+    // 2. Set this’s headers to a new Headers object with this’s relevant
+    // Realm, whose header list is this’s response’s header list and guard
+    // is "response".
+    this[kHeaders] = new Headers(kConstruct)
+    this[kHeaders][kGuard] = 'response'
+    this[kHeaders][kHeadersList] = this[kState].headersList
+    this[kHeaders][kRealm] = this[kRealm]
+
+    // 3. Let bodyWithType be null.
+    let bodyWithType = null
+
+    // 4. If body is non-null, then set bodyWithType to the result of extracting body.
+    if (body != null) {
+      const [extractedBody, type] = extractBody(body)
+      bodyWithType = { body: extractedBody, type }
+    }
+
+    // 5. Perform initialize a response given this, init, and bodyWithType.
+    initializeResponse(this, init, bodyWithType)
+  }
+
+  // Returns response’s type, e.g., "cors".
+  get type () {
+    webidl.brandCheck(this, Response)
+
+    // The type getter steps are to return this’s response’s type.
+    return this[kState].type
+  }
+
+  // Returns response’s URL, if it has one; otherwise the empty string.
+  get url () {
+    webidl.brandCheck(this, Response)
+
+    const urlList = this[kState].urlList
+
+    // The url getter steps are to return the empty string if this’s
+    // response’s URL is null; otherwise this’s response’s URL,
+    // serialized with exclude fragment set to true.
+    const url = urlList[urlList.length - 1] ?? null
+
+    if (url === null) {
+      return ''
+    }
+
+    return URLSerializer(url, true)
+  }
+
+  // Returns whether response was obtained through a redirect.
+  get redirected () {
+    webidl.brandCheck(this, Response)
+
+    // The redirected getter steps are to return true if this’s response’s URL
+    // list has more than one item; otherwise false.
+    return this[kState].urlList.length > 1
+  }
+
+  // Returns response’s status.
+  get status () {
+    webidl.brandCheck(this, Response)
+
+    // The status getter steps are to return this’s response’s status.
+    return this[kState].status
+  }
+
+  // Returns whether response’s status is an ok status.
+  get ok () {
+    webidl.brandCheck(this, Response)
+
+    // The ok getter steps are to return true if this’s response’s status is an
+    // ok status; otherwise false.
+    return this[kState].status >= 200 && this[kState].status <= 299
+  }
+
+  // Returns response’s status message.
+  get statusText () {
+    webidl.brandCheck(this, Response)
+
+    // The statusText getter steps are to return this’s response’s status
+    // message.
+    return this[kState].statusText
+  }
+
+  // Returns response’s headers as Headers.
+  get headers () {
+    webidl.brandCheck(this, Response)
+
+    // The headers getter steps are to return this’s headers.
+    return this[kHeaders]
+  }
+
+  get body () {
+    webidl.brandCheck(this, Response)
+
+    return this[kState].body ? this[kState].body.stream : null
+  }
+
+  get bodyUsed () {
+    webidl.brandCheck(this, Response)
+
+    return !!this[kState].body && util.isDisturbed(this[kState].body.stream)
+  }
+
+  // Returns a clone of response.
+  clone () {
+    webidl.brandCheck(this, Response)
+
+    // 1. If this is unusable, then throw a TypeError.
+    if (this.bodyUsed || (this.body && this.body.locked)) {
+      throw webidl.errors.exception({
+        header: 'Response.clone',
+        message: 'Body has already been consumed.'
+      })
+    }
+
+    // 2. Let clonedResponse be the result of cloning this’s response.
+    const clonedResponse = cloneResponse(this[kState])
+
+    // 3. Return the result of creating a Response object, given
+    // clonedResponse, this’s headers’s guard, and this’s relevant Realm.
+    const clonedResponseObject = new Response()
+    clonedResponseObject[kState] = clonedResponse
+    clonedResponseObject[kRealm] = this[kRealm]
+    clonedResponseObject[kHeaders][kHeadersList] = clonedResponse.headersList
+    clonedResponseObject[kHeaders][kGuard] = this[kHeaders][kGuard]
+    clonedResponseObject[kHeaders][kRealm] = this[kHeaders][kRealm]
+
+    return clonedResponseObject
+  }
+}
+
+mixinBody(Response)
+
+Object.defineProperties(Response.prototype, {
+  type: kEnumerableProperty,
+  url: kEnumerableProperty,
+  status: kEnumerableProperty,
+  ok: kEnumerableProperty,
+  redirected: kEnumerableProperty,
+  statusText: kEnumerableProperty,
+  headers: kEnumerableProperty,
+  clone: kEnumerableProperty,
+  body: kEnumerableProperty,
+  bodyUsed: kEnumerableProperty,
+  [Symbol.toStringTag]: {
+    value: 'Response',
+    configurable: true
+  }
+})
+
+Object.defineProperties(Response, {
+  json: kEnumerableProperty,
+  redirect: kEnumerableProperty,
+  error: kEnumerableProperty
+})
+
+// https://fetch.spec.whatwg.org/#concept-response-clone
+function cloneResponse (response) {
+  // To clone a response response, run these steps:
+
+  // 1. If response is a filtered response, then return a new identical
+  // filtered response whose internal response is a clone of response’s
+  // internal response.
+  if (response.internalResponse) {
+    return filterResponse(
+      cloneResponse(response.internalResponse),
+      response.type
+    )
+  }
+
+  // 2. Let newResponse be a copy of response, except for its body.
+  const newResponse = makeResponse({ ...response, body: null })
+
+  // 3. If response’s body is non-null, then set newResponse’s body to the
+  // result of cloning response’s body.
+  if (response.body != null) {
+    newResponse.body = cloneBody(response.body)
+  }
+
+  // 4. Return newResponse.
+  return newResponse
+}
+
+function makeResponse (init) {
+  return {
+    aborted: false,
+    rangeRequested: false,
+    timingAllowPassed: false,
+    requestIncludesCredentials: false,
+    type: 'default',
+    status: 200,
+    timingInfo: null,
+    cacheState: '',
+    statusText: '',
+    ...init,
+    headersList: init.headersList
+      ? new HeadersList(init.headersList)
+      : new HeadersList(),
+    urlList: init.urlList ? [...init.urlList] : []
+  }
+}
+
+function makeNetworkError (reason) {
+  const isError = isErrorLike(reason)
+  return makeResponse({
+    type: 'error',
+    status: 0,
+    error: isError
+      ? reason
+      : new Error(reason ? String(reason) : reason),
+    aborted: reason && reason.name === 'AbortError'
+  })
+}
+
+function makeFilteredResponse (response, state) {
+  state = {
+    internalResponse: response,
+    ...state
+  }
+
+  return new Proxy(response, {
+    get (target, p) {
+      return p in state ? state[p] : target[p]
+    },
+    set (target, p, value) {
+      assert(!(p in state))
+      target[p] = value
+      return true
+    }
+  })
+}
+
+// https://fetch.spec.whatwg.org/#concept-filtered-response
+function filterResponse (response, type) {
+  // Set response to the following filtered response with response as its
+  // internal response, depending on request’s response tainting:
+  if (type === 'basic') {
+    // A basic filtered response is a filtered response whose type is "basic"
+    // and header list excludes any headers in internal response’s header list
+    // whose name is a forbidden response-header name.
+
+    // Note: undici does not implement forbidden response-header names
+    return makeFilteredResponse(response, {
+      type: 'basic',
+      headersList: response.headersList
+    })
+  } else if (type === 'cors') {
+    // A CORS filtered response is a filtered response whose type is "cors"
+    // and header list excludes any headers in internal response’s header
+    // list whose name is not a CORS-safelisted response-header name, given
+    // internal response’s CORS-exposed header-name list.
+
+    // Note: undici does not implement CORS-safelisted response-header names
+    return makeFilteredResponse(response, {
+      type: 'cors',
+      headersList: response.headersList
+    })
+  } else if (type === 'opaque') {
+    // An opaque filtered response is a filtered response whose type is
+    // "opaque", URL list is the empty list, status is 0, status message
+    // is the empty byte sequence, header list is empty, and body is null.
+
+    return makeFilteredResponse(response, {
+      type: 'opaque',
+      urlList: Object.freeze([]),
+      status: 0,
+      statusText: '',
+      body: null
+    })
+  } else if (type === 'opaqueredirect') {
+    // An opaque-redirect filtered response is a filtered response whose type
+    // is "opaqueredirect", status is 0, status message is the empty byte
+    // sequence, header list is empty, and body is null.
+
+    return makeFilteredResponse(response, {
+      type: 'opaqueredirect',
+      status: 0,
+      statusText: '',
+      headersList: [],
+      body: null
+    })
+  } else {
+    assert(false)
+  }
+}
+
+// https://fetch.spec.whatwg.org/#appropriate-network-error
+function makeAppropriateNetworkError (fetchParams, err = null) {
+  // 1. Assert: fetchParams is canceled.
+  assert(isCancelled(fetchParams))
+
+  // 2. Return an aborted network error if fetchParams is aborted;
+  // otherwise return a network error.
+  return isAborted(fetchParams)
+    ? makeNetworkError(Object.assign(new DOMException('The operation was aborted.', 'AbortError'), { cause: err }))
+    : makeNetworkError(Object.assign(new DOMException('Request was cancelled.'), { cause: err }))
+}
+
+// https://whatpr.org/fetch/1392.html#initialize-a-response
+function initializeResponse (response, init, body) {
+  // 1. If init["status"] is not in the range 200 to 599, inclusive, then
+  //    throw a RangeError.
+  if (init.status !== null && (init.status < 200 || init.status > 599)) {
+    throw new RangeError('init["status"] must be in the range of 200 to 599, inclusive.')
+  }
+
+  // 2. If init["statusText"] does not match the reason-phrase token production,
+  //    then throw a TypeError.
+  if ('statusText' in init && init.statusText != null) {
+    // See, https://datatracker.ietf.org/doc/html/rfc7230#section-3.1.2:
+    //   reason-phrase  = *( HTAB / SP / VCHAR / obs-text )
+    if (!isValidReasonPhrase(String(init.statusText))) {
+      throw new TypeError('Invalid statusText')
+    }
+  }
+
+  // 3. Set response’s response’s status to init["status"].
+  if ('status' in init && init.status != null) {
+    response[kState].status = init.status
+  }
+
+  // 4. Set response’s response’s status message to init["statusText"].
+  if ('statusText' in init && init.statusText != null) {
+    response[kState].statusText = init.statusText
+  }
+
+  // 5. If init["headers"] exists, then fill response’s headers with init["headers"].
+  if ('headers' in init && init.headers != null) {
+    fill(response[kHeaders], init.headers)
+  }
+
+  // 6. If body was given, then:
+  if (body) {
+    // 1. If response's status is a null body status, then throw a TypeError.
+    if (nullBodyStatus.includes(response.status)) {
+      throw webidl.errors.exception({
+        header: 'Response constructor',
+        message: 'Invalid response status code ' + response.status
+      })
+    }
+
+    // 2. Set response's body to body's body.
+    response[kState].body = body.body
+
+    // 3. If body's type is non-null and response's header list does not contain
+    //    `Content-Type`, then append (`Content-Type`, body's type) to response's header list.
+    if (body.type != null && !response[kState].headersList.contains('Content-Type')) {
+      response[kState].headersList.append('content-type', body.type)
+    }
+  }
+}
+
+webidl.converters.ReadableStream = webidl.interfaceConverter(
+  ReadableStream
+)
+
+webidl.converters.FormData = webidl.interfaceConverter(
+  FormData
+)
+
+webidl.converters.URLSearchParams = webidl.interfaceConverter(
+  URLSearchParams
+)
+
+// https://fetch.spec.whatwg.org/#typedefdef-xmlhttprequestbodyinit
+webidl.converters.XMLHttpRequestBodyInit = function (V) {
+  if (typeof V === 'string') {
+    return webidl.converters.USVString(V)
+  }
+
+  if (isBlobLike(V)) {
+    return webidl.converters.Blob(V, { strict: false })
+  }
+
+  if (types.isArrayBuffer(V) || types.isTypedArray(V) || types.isDataView(V)) {
+    return webidl.converters.BufferSource(V)
+  }
+
+  if (util.isFormDataLike(V)) {
+    return webidl.converters.FormData(V, { strict: false })
+  }
+
+  if (V instanceof URLSearchParams) {
+    return webidl.converters.URLSearchParams(V)
+  }
+
+  return webidl.converters.DOMString(V)
+}
+
+// https://fetch.spec.whatwg.org/#bodyinit
+webidl.converters.BodyInit = function (V) {
+  if (V instanceof ReadableStream) {
+    return webidl.converters.ReadableStream(V)
+  }
+
+  // Note: the spec doesn't include async iterables,
+  // this is an undici extension.
+  if (V?.[Symbol.asyncIterator]) {
+    return V
+  }
+
+  return webidl.converters.XMLHttpRequestBodyInit(V)
+}
+
+webidl.converters.ResponseInit = webidl.dictionaryConverter([
+  {
+    key: 'status',
+    converter: webidl.converters['unsigned short'],
+    defaultValue: 200
+  },
+  {
+    key: 'statusText',
+    converter: webidl.converters.ByteString,
+    defaultValue: ''
+  },
+  {
+    key: 'headers',
+    converter: webidl.converters.HeadersInit
+  }
+])
+
+module.exports = {
+  makeNetworkError,
+  makeResponse,
+  makeAppropriateNetworkError,
+  filterResponse,
+  Response,
+  cloneResponse
+}
diff --git a/lib/fetch/symbols.js b/lib/fetch/symbols.js
new file mode 100644
index 0000000..0b947d5
--- /dev/null
+++ b/lib/fetch/symbols.js
@@ -0,0 +1,10 @@
+'use strict'
+
+module.exports = {
+  kUrl: Symbol('url'),
+  kHeaders: Symbol('headers'),
+  kSignal: Symbol('signal'),
+  kState: Symbol('state'),
+  kGuard: Symbol('guard'),
+  kRealm: Symbol('realm')
+}
diff --git a/lib/fetch/util.js b/lib/fetch/util.js
new file mode 100644
index 0000000..b12142c
--- /dev/null
+++ b/lib/fetch/util.js
@@ -0,0 +1,1071 @@
+'use strict'
+
+const { redirectStatusSet, referrerPolicySet: referrerPolicyTokens, badPortsSet } = require('./constants')
+const { getGlobalOrigin } = require('./global')
+const { performance } = require('perf_hooks')
+const { isBlobLike, toUSVString, ReadableStreamFrom } = require('../core/util')
+const assert = require('assert')
+const { isUint8Array } = require('util/types')
+
+// https://nodejs.org/api/crypto.html#determining-if-crypto-support-is-unavailable
+/** @type {import('crypto')|undefined} */
+let crypto
+
+try {
+  crypto = require('crypto')
+} catch {
+
+}
+
+function responseURL (response) {
+  // https://fetch.spec.whatwg.org/#responses
+  // A response has an associated URL. It is a pointer to the last URL
+  // in response’s URL list and null if response’s URL list is empty.
+  const urlList = response.urlList
+  const length = urlList.length
+  return length === 0 ? null : urlList[length - 1].toString()
+}
+
+// https://fetch.spec.whatwg.org/#concept-response-location-url
+function responseLocationURL (response, requestFragment) {
+  // 1. If response’s status is not a redirect status, then return null.
+  if (!redirectStatusSet.has(response.status)) {
+    return null
+  }
+
+  // 2. Let location be the result of extracting header list values given
+  // `Location` and response’s header list.
+  let location = response.headersList.get('location')
+
+  // 3. If location is a header value, then set location to the result of
+  //    parsing location with response’s URL.
+  if (location !== null && isValidHeaderValue(location)) {
+    location = new URL(location, responseURL(response))
+  }
+
+  // 4. If location is a URL whose fragment is null, then set location’s
+  // fragment to requestFragment.
+  if (location && !location.hash) {
+    location.hash = requestFragment
+  }
+
+  // 5. Return location.
+  return location
+}
+
+/** @returns {URL} */
+function requestCurrentURL (request) {
+  return request.urlList[request.urlList.length - 1]
+}
+
+function requestBadPort (request) {
+  // 1. Let url be request’s current URL.
+  const url = requestCurrentURL(request)
+
+  // 2. If url’s scheme is an HTTP(S) scheme and url’s port is a bad port,
+  // then return blocked.
+  if (urlIsHttpHttpsScheme(url) && badPortsSet.has(url.port)) {
+    return 'blocked'
+  }
+
+  // 3. Return allowed.
+  return 'allowed'
+}
+
+function isErrorLike (object) {
+  return object instanceof Error || (
+    object?.constructor?.name === 'Error' ||
+    object?.constructor?.name === 'DOMException'
+  )
+}
+
+// Check whether |statusText| is a ByteString and
+// matches the Reason-Phrase token production.
+// RFC 2616: https://tools.ietf.org/html/rfc2616
+// RFC 7230: https://tools.ietf.org/html/rfc7230
+// "reason-phrase = *( HTAB / SP / VCHAR / obs-text )"
+// https://github.com/chromium/chromium/blob/94.0.4604.1/third_party/blink/renderer/core/fetch/response.cc#L116
+function isValidReasonPhrase (statusText) {
+  for (let i = 0; i < statusText.length; ++i) {
+    const c = statusText.charCodeAt(i)
+    if (
+      !(
+        (
+          c === 0x09 || // HTAB
+          (c >= 0x20 && c <= 0x7e) || // SP / VCHAR
+          (c >= 0x80 && c <= 0xff)
+        ) // obs-text
+      )
+    ) {
+      return false
+    }
+  }
+  return true
+}
+
+/**
+ * @see https://tools.ietf.org/html/rfc7230#section-3.2.6
+ * @param {number} c
+ */
+function isTokenCharCode (c) {
+  switch (c) {
+    case 0x22:
+    case 0x28:
+    case 0x29:
+    case 0x2c:
+    case 0x2f:
+    case 0x3a:
+    case 0x3b:
+    case 0x3c:
+    case 0x3d:
+    case 0x3e:
+    case 0x3f:
+    case 0x40:
+    case 0x5b:
+    case 0x5c:
+    case 0x5d:
+    case 0x7b:
+    case 0x7d:
+      // DQUOTE and "(),/:;<=>?@[\]{}"
+      return false
+    default:
+      // VCHAR %x21-7E
+      return c >= 0x21 && c <= 0x7e
+  }
+}
+
+/**
+ * @param {string} characters
+ */
+function isValidHTTPToken (characters) {
+  if (characters.length === 0) {
+    return false
+  }
+  for (let i = 0; i < characters.length; ++i) {
+    if (!isTokenCharCode(characters.charCodeAt(i))) {
+      return false
+    }
+  }
+  return true
+}
+
+/**
+ * @see https://fetch.spec.whatwg.org/#header-name
+ * @param {string} potentialValue
+ */
+function isValidHeaderName (potentialValue) {
+  return isValidHTTPToken(potentialValue)
+}
+
+/**
+ * @see https://fetch.spec.whatwg.org/#header-value
+ * @param {string} potentialValue
+ */
+function isValidHeaderValue (potentialValue) {
+  // - Has no leading or trailing HTTP tab or space bytes.
+  // - Contains no 0x00 (NUL) or HTTP newline bytes.
+  if (
+    potentialValue.startsWith('\t') ||
+    potentialValue.startsWith(' ') ||
+    potentialValue.endsWith('\t') ||
+    potentialValue.endsWith(' ')
+  ) {
+    return false
+  }
+
+  if (
+    potentialValue.includes('\0') ||
+    potentialValue.includes('\r') ||
+    potentialValue.includes('\n')
+  ) {
+    return false
+  }
+
+  return true
+}
+
+// https://w3c.github.io/webappsec-referrer-policy/#set-requests-referrer-policy-on-redirect
+function setRequestReferrerPolicyOnRedirect (request, actualResponse) {
+  //  Given a request request and a response actualResponse, this algorithm
+  //  updates request’s referrer policy according to the Referrer-Policy
+  //  header (if any) in actualResponse.
+
+  // 1. Let policy be the result of executing § 8.1 Parse a referrer policy
+  // from a Referrer-Policy header on actualResponse.
+
+  // 8.1 Parse a referrer policy from a Referrer-Policy header
+  // 1. Let policy-tokens be the result of extracting header list values given `Referrer-Policy` and response’s header list.
+  const { headersList } = actualResponse
+  // 2. Let policy be the empty string.
+  // 3. For each token in policy-tokens, if token is a referrer policy and token is not the empty string, then set policy to token.
+  // 4. Return policy.
+  const policyHeader = (headersList.get('referrer-policy') ?? '').split(',')
+
+  // Note: As the referrer-policy can contain multiple policies
+  // separated by comma, we need to loop through all of them
+  // and pick the first valid one.
+  // Ref: https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Referrer-Policy#specify_a_fallback_policy
+  let policy = ''
+  if (policyHeader.length > 0) {
+    // The right-most policy takes precedence.
+    // The left-most policy is the fallback.
+    for (let i = policyHeader.length; i !== 0; i--) {
+      const token = policyHeader[i - 1].trim()
+      if (referrerPolicyTokens.has(token)) {
+        policy = token
+        break
+      }
+    }
+  }
+
+  // 2. If policy is not the empty string, then set request’s referrer policy to policy.
+  if (policy !== '') {
+    request.referrerPolicy = policy
+  }
+}
+
+// https://fetch.spec.whatwg.org/#cross-origin-resource-policy-check
+function crossOriginResourcePolicyCheck () {
+  // TODO
+  return 'allowed'
+}
+
+// https://fetch.spec.whatwg.org/#concept-cors-check
+function corsCheck () {
+  // TODO
+  return 'success'
+}
+
+// https://fetch.spec.whatwg.org/#concept-tao-check
+function TAOCheck () {
+  // TODO
+  return 'success'
+}
+
+function appendFetchMetadata (httpRequest) {
+  //  https://w3c.github.io/webappsec-fetch-metadata/#sec-fetch-dest-header
+  //  TODO
+
+  //  https://w3c.github.io/webappsec-fetch-metadata/#sec-fetch-mode-header
+
+  //  1. Assert: r’s url is a potentially trustworthy URL.
+  //  TODO
+
+  //  2. Let header be a Structured Header whose value is a token.
+  let header = null
+
+  //  3. Set header’s value to r’s mode.
+  header = httpRequest.mode
+
+  //  4. Set a structured field value `Sec-Fetch-Mode`/header in r’s header list.
+  httpRequest.headersList.set('sec-fetch-mode', header)
+
+  //  https://w3c.github.io/webappsec-fetch-metadata/#sec-fetch-site-header
+  //  TODO
+
+  //  https://w3c.github.io/webappsec-fetch-metadata/#sec-fetch-user-header
+  //  TODO
+}
+
+// https://fetch.spec.whatwg.org/#append-a-request-origin-header
+function appendRequestOriginHeader (request) {
+  // 1. Let serializedOrigin be the result of byte-serializing a request origin with request.
+  let serializedOrigin = request.origin
+
+  // 2. If request’s response tainting is "cors" or request’s mode is "websocket", then append (`Origin`, serializedOrigin) to request’s header list.
+  if (request.responseTainting === 'cors' || request.mode === 'websocket') {
+    if (serializedOrigin) {
+      request.headersList.append('origin', serializedOrigin)
+    }
+
+  // 3. Otherwise, if request’s method is neither `GET` nor `HEAD`, then:
+  } else if (request.method !== 'GET' && request.method !== 'HEAD') {
+    // 1. Switch on request’s referrer policy:
+    switch (request.referrerPolicy) {
+      case 'no-referrer':
+        // Set serializedOrigin to `null`.
+        serializedOrigin = null
+        break
+      case 'no-referrer-when-downgrade':
+      case 'strict-origin':
+      case 'strict-origin-when-cross-origin':
+        // If request’s origin is a tuple origin, its scheme is "https", and request’s current URL’s scheme is not "https", then set serializedOrigin to `null`.
+        if (request.origin && urlHasHttpsScheme(request.origin) && !urlHasHttpsScheme(requestCurrentURL(request))) {
+          serializedOrigin = null
+        }
+        break
+      case 'same-origin':
+        // If request’s origin is not same origin with request’s current URL’s origin, then set serializedOrigin to `null`.
+        if (!sameOrigin(request, requestCurrentURL(request))) {
+          serializedOrigin = null
+        }
+        break
+      default:
+        // Do nothing.
+    }
+
+    if (serializedOrigin) {
+      // 2. Append (`Origin`, serializedOrigin) to request’s header list.
+      request.headersList.append('origin', serializedOrigin)
+    }
+  }
+}
+
+function coarsenedSharedCurrentTime (crossOriginIsolatedCapability) {
+  // TODO
+  return performance.now()
+}
+
+// https://fetch.spec.whatwg.org/#create-an-opaque-timing-info
+function createOpaqueTimingInfo (timingInfo) {
+  return {
+    startTime: timingInfo.startTime ?? 0,
+    redirectStartTime: 0,
+    redirectEndTime: 0,
+    postRedirectStartTime: timingInfo.startTime ?? 0,
+    finalServiceWorkerStartTime: 0,
+    finalNetworkResponseStartTime: 0,
+    finalNetworkRequestStartTime: 0,
+    endTime: 0,
+    encodedBodySize: 0,
+    decodedBodySize: 0,
+    finalConnectionTimingInfo: null
+  }
+}
+
+// https://html.spec.whatwg.org/multipage/origin.html#policy-container
+function makePolicyContainer () {
+  // Note: the fetch spec doesn't make use of embedder policy or CSP list
+  return {
+    referrerPolicy: 'strict-origin-when-cross-origin'
+  }
+}
+
+// https://html.spec.whatwg.org/multipage/origin.html#clone-a-policy-container
+function clonePolicyContainer (policyContainer) {
+  return {
+    referrerPolicy: policyContainer.referrerPolicy
+  }
+}
+
+// https://w3c.github.io/webappsec-referrer-policy/#determine-requests-referrer
+function determineRequestsReferrer (request) {
+  // 1. Let policy be request's referrer policy.
+  const policy = request.referrerPolicy
+
+  // Note: policy cannot (shouldn't) be null or an empty string.
+  assert(policy)
+
+  // 2. Let environment be request’s client.
+
+  let referrerSource = null
+
+  // 3. Switch on request’s referrer:
+  if (request.referrer === 'client') {
+    // Note: node isn't a browser and doesn't implement document/iframes,
+    // so we bypass this step and replace it with our own.
+
+    const globalOrigin = getGlobalOrigin()
+
+    if (!globalOrigin || globalOrigin.origin === 'null') {
+      return 'no-referrer'
+    }
+
+    // note: we need to clone it as it's mutated
+    referrerSource = new URL(globalOrigin)
+  } else if (request.referrer instanceof URL) {
+    // Let referrerSource be request’s referrer.
+    referrerSource = request.referrer
+  }
+
+  // 4. Let request’s referrerURL be the result of stripping referrerSource for
+  //    use as a referrer.
+  let referrerURL = stripURLForReferrer(referrerSource)
+
+  // 5. Let referrerOrigin be the result of stripping referrerSource for use as
+  //    a referrer, with the origin-only flag set to true.
+  const referrerOrigin = stripURLForReferrer(referrerSource, true)
+
+  // 6. If the result of serializing referrerURL is a string whose length is
+  //    greater than 4096, set referrerURL to referrerOrigin.
+  if (referrerURL.toString().length > 4096) {
+    referrerURL = referrerOrigin
+  }
+
+  const areSameOrigin = sameOrigin(request, referrerURL)
+  const isNonPotentiallyTrustWorthy = isURLPotentiallyTrustworthy(referrerURL) &&
+    !isURLPotentiallyTrustworthy(request.url)
+
+  // 8. Execute the switch statements corresponding to the value of policy:
+  switch (policy) {
+    case 'origin': return referrerOrigin != null ? referrerOrigin : stripURLForReferrer(referrerSource, true)
+    case 'unsafe-url': return referrerURL
+    case 'same-origin':
+      return areSameOrigin ? referrerOrigin : 'no-referrer'
+    case 'origin-when-cross-origin':
+      return areSameOrigin ? referrerURL : referrerOrigin
+    case 'strict-origin-when-cross-origin': {
+      const currentURL = requestCurrentURL(request)
+
+      // 1. If the origin of referrerURL and the origin of request’s current
+      //    URL are the same, then return referrerURL.
+      if (sameOrigin(referrerURL, currentURL)) {
+        return referrerURL
+      }
+
+      // 2. If referrerURL is a potentially trustworthy URL and request’s
+      //    current URL is not a potentially trustworthy URL, then return no
+      //    referrer.
+      if (isURLPotentiallyTrustworthy(referrerURL) && !isURLPotentiallyTrustworthy(currentURL)) {
+        return 'no-referrer'
+      }
+
+      // 3. Return referrerOrigin.
+      return referrerOrigin
+    }
+    case 'strict-origin': // eslint-disable-line
+      /**
+         * 1. If referrerURL is a potentially trustworthy URL and
+         * request’s current URL is not a potentially trustworthy URL,
+         * then return no referrer.
+         * 2. Return referrerOrigin
+        */
+    case 'no-referrer-when-downgrade': // eslint-disable-line
+      /**
+       * 1. If referrerURL is a potentially trustworthy URL and
+       * request’s current URL is not a potentially trustworthy URL,
+       * then return no referrer.
+       * 2. Return referrerOrigin
+      */
+
+    default: // eslint-disable-line
+      return isNonPotentiallyTrustWorthy ? 'no-referrer' : referrerOrigin
+  }
+}
+
+/**
+ * @see https://w3c.github.io/webappsec-referrer-policy/#strip-url
+ * @param {URL} url
+ * @param {boolean|undefined} originOnly
+ */
+function stripURLForReferrer (url, originOnly) {
+  // 1. Assert: url is a URL.
+  assert(url instanceof URL)
+
+  // 2. If url’s scheme is a local scheme, then return no referrer.
+  if (url.protocol === 'file:' || url.protocol === 'about:' || url.protocol === 'blank:') {
+    return 'no-referrer'
+  }
+
+  // 3. Set url’s username to the empty string.
+  url.username = ''
+
+  // 4. Set url’s password to the empty string.
+  url.password = ''
+
+  // 5. Set url’s fragment to null.
+  url.hash = ''
+
+  // 6. If the origin-only flag is true, then:
+  if (originOnly) {
+    // 1. Set url’s path to « the empty string ».
+    url.pathname = ''
+
+    // 2. Set url’s query to null.
+    url.search = ''
+  }
+
+  // 7. Return url.
+  return url
+}
+
+function isURLPotentiallyTrustworthy (url) {
+  if (!(url instanceof URL)) {
+    return false
+  }
+
+  // If child of about, return true
+  if (url.href === 'about:blank' || url.href === 'about:srcdoc') {
+    return true
+  }
+
+  // If scheme is data, return true
+  if (url.protocol === 'data:') return true
+
+  // If file, return true
+  if (url.protocol === 'file:') return true
+
+  return isOriginPotentiallyTrustworthy(url.origin)
+
+  function isOriginPotentiallyTrustworthy (origin) {
+    // If origin is explicitly null, return false
+    if (origin == null || origin === 'null') return false
+
+    const originAsURL = new URL(origin)
+
+    // If secure, return true
+    if (originAsURL.protocol === 'https:' || originAsURL.protocol === 'wss:') {
+      return true
+    }
+
+    // If localhost or variants, return true
+    if (/^127(?:\.[0-9]+){0,2}\.[0-9]+$|^\[(?:0*:)*?:?0*1\]$/.test(originAsURL.hostname) ||
+     (originAsURL.hostname === 'localhost' || originAsURL.hostname.includes('localhost.')) ||
+     (originAsURL.hostname.endsWith('.localhost'))) {
+      return true
+    }
+
+    // If any other, return false
+    return false
+  }
+}
+
+/**
+ * @see https://w3c.github.io/webappsec-subresource-integrity/#does-response-match-metadatalist
+ * @param {Uint8Array} bytes
+ * @param {string} metadataList
+ */
+function bytesMatch (bytes, metadataList) {
+  // If node is not built with OpenSSL support, we cannot check
+  // a request's integrity, so allow it by default (the spec will
+  // allow requests if an invalid hash is given, as precedence).
+  /* istanbul ignore if: only if node is built with --without-ssl */
+  if (crypto === undefined) {
+    return true
+  }
+
+  // 1. Let parsedMetadata be the result of parsing metadataList.
+  const parsedMetadata = parseMetadata(metadataList)
+
+  // 2. If parsedMetadata is no metadata, return true.
+  if (parsedMetadata === 'no metadata') {
+    return true
+  }
+
+  // 3. If parsedMetadata is the empty set, return true.
+  if (parsedMetadata.length === 0) {
+    return true
+  }
+
+  // 4. Let metadata be the result of getting the strongest
+  //    metadata from parsedMetadata.
+  const list = parsedMetadata.sort((c, d) => d.algo.localeCompare(c.algo))
+  // get the strongest algorithm
+  const strongest = list[0].algo
+  // get all entries that use the strongest algorithm; ignore weaker
+  const metadata = list.filter((item) => item.algo === strongest)
+
+  // 5. For each item in metadata:
+  for (const item of metadata) {
+    // 1. Let algorithm be the alg component of item.
+    const algorithm = item.algo
+
+    // 2. Let expectedValue be the val component of item.
+    let expectedValue = item.hash
+
+    // See https://github.com/web-platform-tests/wpt/commit/e4c5cc7a5e48093220528dfdd1c4012dc3837a0e
+    // "be liberal with padding". This is annoying, and it's not even in the spec.
+
+    if (expectedValue.endsWith('==')) {
+      expectedValue = expectedValue.slice(0, -2)
+    }
+
+    // 3. Let actualValue be the result of applying algorithm to bytes.
+    let actualValue = crypto.createHash(algorithm).update(bytes).digest('base64')
+
+    if (actualValue.endsWith('==')) {
+      actualValue = actualValue.slice(0, -2)
+    }
+
+    // 4. If actualValue is a case-sensitive match for expectedValue,
+    //    return true.
+    if (actualValue === expectedValue) {
+      return true
+    }
+
+    let actualBase64URL = crypto.createHash(algorithm).update(bytes).digest('base64url')
+
+    if (actualBase64URL.endsWith('==')) {
+      actualBase64URL = actualBase64URL.slice(0, -2)
+    }
+
+    if (actualBase64URL === expectedValue) {
+      return true
+    }
+  }
+
+  // 6. Return false.
+  return false
+}
+
+// https://w3c.github.io/webappsec-subresource-integrity/#grammardef-hash-with-options
+// https://www.w3.org/TR/CSP2/#source-list-syntax
+// https://www.rfc-editor.org/rfc/rfc5234#appendix-B.1
+const parseHashWithOptions = /((?<algo>sha256|sha384|sha512)-(?<hash>[A-z0-9+/]{1}.*={0,2}))( +[\x21-\x7e]?)?/i
+
+/**
+ * @see https://w3c.github.io/webappsec-subresource-integrity/#parse-metadata
+ * @param {string} metadata
+ */
+function parseMetadata (metadata) {
+  // 1. Let result be the empty set.
+  /** @type {{ algo: string, hash: string }[]} */
+  const result = []
+
+  // 2. Let empty be equal to true.
+  let empty = true
+
+  const supportedHashes = crypto.getHashes()
+
+  // 3. For each token returned by splitting metadata on spaces:
+  for (const token of metadata.split(' ')) {
+    // 1. Set empty to false.
+    empty = false
+
+    // 2. Parse token as a hash-with-options.
+    const parsedToken = parseHashWithOptions.exec(token)
+
+    // 3. If token does not parse, continue to the next token.
+    if (parsedToken === null || parsedToken.groups === undefined) {
+      // Note: Chromium blocks the request at this point, but Firefox
+      // gives a warning that an invalid integrity was given. The
+      // correct behavior is to ignore these, and subsequently not
+      // check the integrity of the resource.
+      continue
+    }
+
+    // 4. Let algorithm be the hash-algo component of token.
+    const algorithm = parsedToken.groups.algo
+
+    // 5. If algorithm is a hash function recognized by the user
+    //    agent, add the parsed token to result.
+    if (supportedHashes.includes(algorithm.toLowerCase())) {
+      result.push(parsedToken.groups)
+    }
+  }
+
+  // 4. Return no metadata if empty is true, otherwise return result.
+  if (empty === true) {
+    return 'no metadata'
+  }
+
+  return result
+}
+
+// https://w3c.github.io/webappsec-upgrade-insecure-requests/#upgrade-request
+function tryUpgradeRequestToAPotentiallyTrustworthyURL (request) {
+  // TODO
+}
+
+/**
+ * @link {https://html.spec.whatwg.org/multipage/origin.html#same-origin}
+ * @param {URL} A
+ * @param {URL} B
+ */
+function sameOrigin (A, B) {
+  // 1. If A and B are the same opaque origin, then return true.
+  if (A.origin === B.origin && A.origin === 'null') {
+    return true
+  }
+
+  // 2. If A and B are both tuple origins and their schemes,
+  //    hosts, and port are identical, then return true.
+  if (A.protocol === B.protocol && A.hostname === B.hostname && A.port === B.port) {
+    return true
+  }
+
+  // 3. Return false.
+  return false
+}
+
+function createDeferredPromise () {
+  let res
+  let rej
+  const promise = new Promise((resolve, reject) => {
+    res = resolve
+    rej = reject
+  })
+
+  return { promise, resolve: res, reject: rej }
+}
+
+function isAborted (fetchParams) {
+  return fetchParams.controller.state === 'aborted'
+}
+
+function isCancelled (fetchParams) {
+  return fetchParams.controller.state === 'aborted' ||
+    fetchParams.controller.state === 'terminated'
+}
+
+const normalizeMethodRecord = {
+  delete: 'DELETE',
+  DELETE: 'DELETE',
+  get: 'GET',
+  GET: 'GET',
+  head: 'HEAD',
+  HEAD: 'HEAD',
+  options: 'OPTIONS',
+  OPTIONS: 'OPTIONS',
+  post: 'POST',
+  POST: 'POST',
+  put: 'PUT',
+  PUT: 'PUT'
+}
+
+// Note: object prototypes should not be able to be referenced. e.g. `Object#hasOwnProperty`.
+Object.setPrototypeOf(normalizeMethodRecord, null)
+
+/**
+ * @see https://fetch.spec.whatwg.org/#concept-method-normalize
+ * @param {string} method
+ */
+function normalizeMethod (method) {
+  return normalizeMethodRecord[method.toLowerCase()] ?? method
+}
+
+// https://infra.spec.whatwg.org/#serialize-a-javascript-value-to-a-json-string
+function serializeJavascriptValueToJSONString (value) {
+  // 1. Let result be ? Call(%JSON.stringify%, undefined, « value »).
+  const result = JSON.stringify(value)
+
+  // 2. If result is undefined, then throw a TypeError.
+  if (result === undefined) {
+    throw new TypeError('Value is not JSON serializable')
+  }
+
+  // 3. Assert: result is a string.
+  assert(typeof result === 'string')
+
+  // 4. Return result.
+  return result
+}
+
+// https://tc39.es/ecma262/#sec-%25iteratorprototype%25-object
+const esIteratorPrototype = Object.getPrototypeOf(Object.getPrototypeOf([][Symbol.iterator]()))
+
+/**
+ * @see https://webidl.spec.whatwg.org/#dfn-iterator-prototype-object
+ * @param {() => unknown[]} iterator
+ * @param {string} name name of the instance
+ * @param {'key'|'value'|'key+value'} kind
+ */
+function makeIterator (iterator, name, kind) {
+  const object = {
+    index: 0,
+    kind,
+    target: iterator
+  }
+
+  const i = {
+    next () {
+      // 1. Let interface be the interface for which the iterator prototype object exists.
+
+      // 2. Let thisValue be the this value.
+
+      // 3. Let object be ? ToObject(thisValue).
+
+      // 4. If object is a platform object, then perform a security
+      //    check, passing:
+
+      // 5. If object is not a default iterator object for interface,
+      //    then throw a TypeError.
+      if (Object.getPrototypeOf(this) !== i) {
+        throw new TypeError(
+          `'next' called on an object that does not implement interface ${name} Iterator.`
+        )
+      }
+
+      // 6. Let index be object’s index.
+      // 7. Let kind be object’s kind.
+      // 8. Let values be object’s target's value pairs to iterate over.
+      const { index, kind, target } = object
+      const values = target()
+
+      // 9. Let len be the length of values.
+      const len = values.length
+
+      // 10. If index is greater than or equal to len, then return
+      //     CreateIterResultObject(undefined, true).
+      if (index >= len) {
+        return { value: undefined, done: true }
+      }
+
+      // 11. Let pair be the entry in values at index index.
+      const pair = values[index]
+
+      // 12. Set object’s index to index + 1.
+      object.index = index + 1
+
+      // 13. Return the iterator result for pair and kind.
+      return iteratorResult(pair, kind)
+    },
+    // The class string of an iterator prototype object for a given interface is the
+    // result of concatenating the identifier of the interface and the string " Iterator".
+    [Symbol.toStringTag]: `${name} Iterator`
+  }
+
+  // The [[Prototype]] internal slot of an iterator prototype object must be %IteratorPrototype%.
+  Object.setPrototypeOf(i, esIteratorPrototype)
+  // esIteratorPrototype needs to be the prototype of i
+  // which is the prototype of an empty object. Yes, it's confusing.
+  return Object.setPrototypeOf({}, i)
+}
+
+// https://webidl.spec.whatwg.org/#iterator-result
+function iteratorResult (pair, kind) {
+  let result
+
+  // 1. Let result be a value determined by the value of kind:
+  switch (kind) {
+    case 'key': {
+      // 1. Let idlKey be pair’s key.
+      // 2. Let key be the result of converting idlKey to an
+      //    ECMAScript value.
+      // 3. result is key.
+      result = pair[0]
+      break
+    }
+    case 'value': {
+      // 1. Let idlValue be pair’s value.
+      // 2. Let value be the result of converting idlValue to
+      //    an ECMAScript value.
+      // 3. result is value.
+      result = pair[1]
+      break
+    }
+    case 'key+value': {
+      // 1. Let idlKey be pair’s key.
+      // 2. Let idlValue be pair’s value.
+      // 3. Let key be the result of converting idlKey to an
+      //    ECMAScript value.
+      // 4. Let value be the result of converting idlValue to
+      //    an ECMAScript value.
+      // 5. Let array be ! ArrayCreate(2).
+      // 6. Call ! CreateDataProperty(array, "0", key).
+      // 7. Call ! CreateDataProperty(array, "1", value).
+      // 8. result is array.
+      result = pair
+      break
+    }
+  }
+
+  // 2. Return CreateIterResultObject(result, false).
+  return { value: result, done: false }
+}
+
+/**
+ * @see https://fetch.spec.whatwg.org/#body-fully-read
+ */
+async function fullyReadBody (body, processBody, processBodyError) {
+  // 1. If taskDestination is null, then set taskDestination to
+  //    the result of starting a new parallel queue.
+
+  // 2. Let successSteps given a byte sequence bytes be to queue a
+  //    fetch task to run processBody given bytes, with taskDestination.
+  const successSteps = processBody
+
+  // 3. Let errorSteps be to queue a fetch task to run processBodyError,
+  //    with taskDestination.
+  const errorSteps = processBodyError
+
+  // 4. Let reader be the result of getting a reader for body’s stream.
+  //    If that threw an exception, then run errorSteps with that
+  //    exception and return.
+  let reader
+
+  try {
+    reader = body.stream.getReader()
+  } catch (e) {
+    errorSteps(e)
+    return
+  }
+
+  // 5. Read all bytes from reader, given successSteps and errorSteps.
+  try {
+    const result = await readAllBytes(reader)
+    successSteps(result)
+  } catch (e) {
+    errorSteps(e)
+  }
+}
+
+/** @type {ReadableStream} */
+let ReadableStream = globalThis.ReadableStream
+
+function isReadableStreamLike (stream) {
+  if (!ReadableStream) {
+    ReadableStream = require('stream/web').ReadableStream
+  }
+
+  return stream instanceof ReadableStream || (
+    stream[Symbol.toStringTag] === 'ReadableStream' &&
+    typeof stream.tee === 'function'
+  )
+}
+
+const MAXIMUM_ARGUMENT_LENGTH = 65535
+
+/**
+ * @see https://infra.spec.whatwg.org/#isomorphic-decode
+ * @param {number[]|Uint8Array} input
+ */
+function isomorphicDecode (input) {
+  // 1. To isomorphic decode a byte sequence input, return a string whose code point
+  //    length is equal to input’s length and whose code points have the same values
+  //    as the values of input’s bytes, in the same order.
+
+  if (input.length < MAXIMUM_ARGUMENT_LENGTH) {
+    return String.fromCharCode(...input)
+  }
+
+  return input.reduce((previous, current) => previous + String.fromCharCode(current), '')
+}
+
+/**
+ * @param {ReadableStreamController<Uint8Array>} controller
+ */
+function readableStreamClose (controller) {
+  try {
+    controller.close()
+  } catch (err) {
+    // TODO: add comment explaining why this error occurs.
+    if (!err.message.includes('Controller is already closed')) {
+      throw err
+    }
+  }
+}
+
+/**
+ * @see https://infra.spec.whatwg.org/#isomorphic-encode
+ * @param {string} input
+ */
+function isomorphicEncode (input) {
+  // 1. Assert: input contains no code points greater than U+00FF.
+  for (let i = 0; i < input.length; i++) {
+    assert(input.charCodeAt(i) <= 0xFF)
+  }
+
+  // 2. Return a byte sequence whose length is equal to input’s code
+  //    point length and whose bytes have the same values as the
+  //    values of input’s code points, in the same order
+  return input
+}
+
+/**
+ * @see https://streams.spec.whatwg.org/#readablestreamdefaultreader-read-all-bytes
+ * @see https://streams.spec.whatwg.org/#read-loop
+ * @param {ReadableStreamDefaultReader} reader
+ */
+async function readAllBytes (reader) {
+  const bytes = []
+  let byteLength = 0
+
+  while (true) {
+    const { done, value: chunk } = await reader.read()
+
+    if (done) {
+      // 1. Call successSteps with bytes.
+      return Buffer.concat(bytes, byteLength)
+    }
+
+    // 1. If chunk is not a Uint8Array object, call failureSteps
+    //    with a TypeError and abort these steps.
+    if (!isUint8Array(chunk)) {
+      throw new TypeError('Received non-Uint8Array chunk')
+    }
+
+    // 2. Append the bytes represented by chunk to bytes.
+    bytes.push(chunk)
+    byteLength += chunk.length
+
+    // 3. Read-loop given reader, bytes, successSteps, and failureSteps.
+  }
+}
+
+/**
+ * @see https://fetch.spec.whatwg.org/#is-local
+ * @param {URL} url
+ */
+function urlIsLocal (url) {
+  assert('protocol' in url) // ensure it's a url object
+
+  const protocol = url.protocol
+
+  return protocol === 'about:' || protocol === 'blob:' || protocol === 'data:'
+}
+
+/**
+ * @param {string|URL} url
+ */
+function urlHasHttpsScheme (url) {
+  if (typeof url === 'string') {
+    return url.startsWith('https:')
+  }
+
+  return url.protocol === 'https:'
+}
+
+/**
+ * @see https://fetch.spec.whatwg.org/#http-scheme
+ * @param {URL} url
+ */
+function urlIsHttpHttpsScheme (url) {
+  assert('protocol' in url) // ensure it's a url object
+
+  const protocol = url.protocol
+
+  return protocol === 'http:' || protocol === 'https:'
+}
+
+/**
+ * Fetch supports node >= 16.8.0, but Object.hasOwn was added in v16.9.0.
+ */
+const hasOwn = Object.hasOwn || ((dict, key) => Object.prototype.hasOwnProperty.call(dict, key))
+
+module.exports = {
+  isAborted,
+  isCancelled,
+  createDeferredPromise,
+  ReadableStreamFrom,
+  toUSVString,
+  tryUpgradeRequestToAPotentiallyTrustworthyURL,
+  coarsenedSharedCurrentTime,
+  determineRequestsReferrer,
+  makePolicyContainer,
+  clonePolicyContainer,
+  appendFetchMetadata,
+  appendRequestOriginHeader,
+  TAOCheck,
+  corsCheck,
+  crossOriginResourcePolicyCheck,
+  createOpaqueTimingInfo,
+  setRequestReferrerPolicyOnRedirect,
+  isValidHTTPToken,
+  requestBadPort,
+  requestCurrentURL,
+  responseURL,
+  responseLocationURL,
+  isBlobLike,
+  isURLPotentiallyTrustworthy,
+  isValidReasonPhrase,
+  sameOrigin,
+  normalizeMethod,
+  serializeJavascriptValueToJSONString,
+  makeIterator,
+  isValidHeaderName,
+  isValidHeaderValue,
+  hasOwn,
+  isErrorLike,
+  fullyReadBody,
+  bytesMatch,
+  isReadableStreamLike,
+  readableStreamClose,
+  isomorphicEncode,
+  isomorphicDecode,
+  urlIsLocal,
+  urlHasHttpsScheme,
+  urlIsHttpHttpsScheme,
+  readAllBytes,
+  normalizeMethodRecord
+}
diff --git a/lib/fetch/webidl.js b/lib/fetch/webidl.js
new file mode 100644
index 0000000..6fcf2ab
--- /dev/null
+++ b/lib/fetch/webidl.js
@@ -0,0 +1,646 @@
+'use strict'
+
+const { types } = require('util')
+const { hasOwn, toUSVString } = require('./util')
+
+/** @type {import('../../types/webidl').Webidl} */
+const webidl = {}
+webidl.converters = {}
+webidl.util = {}
+webidl.errors = {}
+
+webidl.errors.exception = function (message) {
+  return new TypeError(`${message.header}: ${message.message}`)
+}
+
+webidl.errors.conversionFailed = function (context) {
+  const plural = context.types.length === 1 ? '' : ' one of'
+  const message =
+    `${context.argument} could not be converted to` +
+    `${plural}: ${context.types.join(', ')}.`
+
+  return webidl.errors.exception({
+    header: context.prefix,
+    message
+  })
+}
+
+webidl.errors.invalidArgument = function (context) {
+  return webidl.errors.exception({
+    header: context.prefix,
+    message: `"${context.value}" is an invalid ${context.type}.`
+  })
+}
+
+// https://webidl.spec.whatwg.org/#implements
+webidl.brandCheck = function (V, I, opts = undefined) {
+  if (opts?.strict !== false && !(V instanceof I)) {
+    throw new TypeError('Illegal invocation')
+  } else {
+    return V?.[Symbol.toStringTag] === I.prototype[Symbol.toStringTag]
+  }
+}
+
+webidl.argumentLengthCheck = function ({ length }, min, ctx) {
+  if (length < min) {
+    throw webidl.errors.exception({
+      message: `${min} argument${min !== 1 ? 's' : ''} required, ` +
+               `but${length ? ' only' : ''} ${length} found.`,
+      ...ctx
+    })
+  }
+}
+
+webidl.illegalConstructor = function () {
+  throw webidl.errors.exception({
+    header: 'TypeError',
+    message: 'Illegal constructor'
+  })
+}
+
+// https://tc39.es/ecma262/#sec-ecmascript-data-types-and-values
+webidl.util.Type = function (V) {
+  switch (typeof V) {
+    case 'undefined': return 'Undefined'
+    case 'boolean': return 'Boolean'
+    case 'string': return 'String'
+    case 'symbol': return 'Symbol'
+    case 'number': return 'Number'
+    case 'bigint': return 'BigInt'
+    case 'function':
+    case 'object': {
+      if (V === null) {
+        return 'Null'
+      }
+
+      return 'Object'
+    }
+  }
+}
+
+// https://webidl.spec.whatwg.org/#abstract-opdef-converttoint
+webidl.util.ConvertToInt = function (V, bitLength, signedness, opts = {}) {
+  let upperBound
+  let lowerBound
+
+  // 1. If bitLength is 64, then:
+  if (bitLength === 64) {
+    // 1. Let upperBound be 2^53 − 1.
+    upperBound = Math.pow(2, 53) - 1
+
+    // 2. If signedness is "unsigned", then let lowerBound be 0.
+    if (signedness === 'unsigned') {
+      lowerBound = 0
+    } else {
+      // 3. Otherwise let lowerBound be −2^53 + 1.
+      lowerBound = Math.pow(-2, 53) + 1
+    }
+  } else if (signedness === 'unsigned') {
+    // 2. Otherwise, if signedness is "unsigned", then:
+
+    // 1. Let lowerBound be 0.
+    lowerBound = 0
+
+    // 2. Let upperBound be 2^bitLength − 1.
+    upperBound = Math.pow(2, bitLength) - 1
+  } else {
+    // 3. Otherwise:
+
+    // 1. Let lowerBound be -2^bitLength − 1.
+    lowerBound = Math.pow(-2, bitLength) - 1
+
+    // 2. Let upperBound be 2^bitLength − 1 − 1.
+    upperBound = Math.pow(2, bitLength - 1) - 1
+  }
+
+  // 4. Let x be ? ToNumber(V).
+  let x = Number(V)
+
+  // 5. If x is −0, then set x to +0.
+  if (x === 0) {
+    x = 0
+  }
+
+  // 6. If the conversion is to an IDL type associated
+  //    with the [EnforceRange] extended attribute, then:
+  if (opts.enforceRange === true) {
+    // 1. If x is NaN, +∞, or −∞, then throw a TypeError.
+    if (
+      Number.isNaN(x) ||
+      x === Number.POSITIVE_INFINITY ||
+      x === Number.NEGATIVE_INFINITY
+    ) {
+      throw webidl.errors.exception({
+        header: 'Integer conversion',
+        message: `Could not convert ${V} to an integer.`
+      })
+    }
+
+    // 2. Set x to IntegerPart(x).
+    x = webidl.util.IntegerPart(x)
+
+    // 3. If x < lowerBound or x > upperBound, then
+    //    throw a TypeError.
+    if (x < lowerBound || x > upperBound) {
+      throw webidl.errors.exception({
+        header: 'Integer conversion',
+        message: `Value must be between ${lowerBound}-${upperBound}, got ${x}.`
+      })
+    }
+
+    // 4. Return x.
+    return x
+  }
+
+  // 7. If x is not NaN and the conversion is to an IDL
+  //    type associated with the [Clamp] extended
+  //    attribute, then:
+  if (!Number.isNaN(x) && opts.clamp === true) {
+    // 1. Set x to min(max(x, lowerBound), upperBound).
+    x = Math.min(Math.max(x, lowerBound), upperBound)
+
+    // 2. Round x to the nearest integer, choosing the
+    //    even integer if it lies halfway between two,
+    //    and choosing +0 rather than −0.
+    if (Math.floor(x) % 2 === 0) {
+      x = Math.floor(x)
+    } else {
+      x = Math.ceil(x)
+    }
+
+    // 3. Return x.
+    return x
+  }
+
+  // 8. If x is NaN, +0, +∞, or −∞, then return +0.
+  if (
+    Number.isNaN(x) ||
+    (x === 0 && Object.is(0, x)) ||
+    x === Number.POSITIVE_INFINITY ||
+    x === Number.NEGATIVE_INFINITY
+  ) {
+    return 0
+  }
+
+  // 9. Set x to IntegerPart(x).
+  x = webidl.util.IntegerPart(x)
+
+  // 10. Set x to x modulo 2^bitLength.
+  x = x % Math.pow(2, bitLength)
+
+  // 11. If signedness is "signed" and x ≥ 2^bitLength − 1,
+  //    then return x − 2^bitLength.
+  if (signedness === 'signed' && x >= Math.pow(2, bitLength) - 1) {
+    return x - Math.pow(2, bitLength)
+  }
+
+  // 12. Otherwise, return x.
+  return x
+}
+
+// https://webidl.spec.whatwg.org/#abstract-opdef-integerpart
+webidl.util.IntegerPart = function (n) {
+  // 1. Let r be floor(abs(n)).
+  const r = Math.floor(Math.abs(n))
+
+  // 2. If n < 0, then return -1 × r.
+  if (n < 0) {
+    return -1 * r
+  }
+
+  // 3. Otherwise, return r.
+  return r
+}
+
+// https://webidl.spec.whatwg.org/#es-sequence
+webidl.sequenceConverter = function (converter) {
+  return (V) => {
+    // 1. If Type(V) is not Object, throw a TypeError.
+    if (webidl.util.Type(V) !== 'Object') {
+      throw webidl.errors.exception({
+        header: 'Sequence',
+        message: `Value of type ${webidl.util.Type(V)} is not an Object.`
+      })
+    }
+
+    // 2. Let method be ? GetMethod(V, @@iterator).
+    /** @type {Generator} */
+    const method = V?.[Symbol.iterator]?.()
+    const seq = []
+
+    // 3. If method is undefined, throw a TypeError.
+    if (
+      method === undefined ||
+      typeof method.next !== 'function'
+    ) {
+      throw webidl.errors.exception({
+        header: 'Sequence',
+        message: 'Object is not an iterator.'
+      })
+    }
+
+    // https://webidl.spec.whatwg.org/#create-sequence-from-iterable
+    while (true) {
+      const { done, value } = method.next()
+
+      if (done) {
+        break
+      }
+
+      seq.push(converter(value))
+    }
+
+    return seq
+  }
+}
+
+// https://webidl.spec.whatwg.org/#es-to-record
+webidl.recordConverter = function (keyConverter, valueConverter) {
+  return (O) => {
+    // 1. If Type(O) is not Object, throw a TypeError.
+    if (webidl.util.Type(O) !== 'Object') {
+      throw webidl.errors.exception({
+        header: 'Record',
+        message: `Value of type ${webidl.util.Type(O)} is not an Object.`
+      })
+    }
+
+    // 2. Let result be a new empty instance of record<K, V>.
+    const result = {}
+
+    if (!types.isProxy(O)) {
+      // Object.keys only returns enumerable properties
+      const keys = Object.keys(O)
+
+      for (const key of keys) {
+        // 1. Let typedKey be key converted to an IDL value of type K.
+        const typedKey = keyConverter(key)
+
+        // 2. Let value be ? Get(O, key).
+        // 3. Let typedValue be value converted to an IDL value of type V.
+        const typedValue = valueConverter(O[key])
+
+        // 4. Set result[typedKey] to typedValue.
+        result[typedKey] = typedValue
+      }
+
+      // 5. Return result.
+      return result
+    }
+
+    // 3. Let keys be ? O.[[OwnPropertyKeys]]().
+    const keys = Reflect.ownKeys(O)
+
+    // 4. For each key of keys.
+    for (const key of keys) {
+      // 1. Let desc be ? O.[[GetOwnProperty]](key).
+      const desc = Reflect.getOwnPropertyDescriptor(O, key)
+
+      // 2. If desc is not undefined and desc.[[Enumerable]] is true:
+      if (desc?.enumerable) {
+        // 1. Let typedKey be key converted to an IDL value of type K.
+        const typedKey = keyConverter(key)
+
+        // 2. Let value be ? Get(O, key).
+        // 3. Let typedValue be value converted to an IDL value of type V.
+        const typedValue = valueConverter(O[key])
+
+        // 4. Set result[typedKey] to typedValue.
+        result[typedKey] = typedValue
+      }
+    }
+
+    // 5. Return result.
+    return result
+  }
+}
+
+webidl.interfaceConverter = function (i) {
+  return (V, opts = {}) => {
+    if (opts.strict !== false && !(V instanceof i)) {
+      throw webidl.errors.exception({
+        header: i.name,
+        message: `Expected ${V} to be an instance of ${i.name}.`
+      })
+    }
+
+    return V
+  }
+}
+
+webidl.dictionaryConverter = function (converters) {
+  return (dictionary) => {
+    const type = webidl.util.Type(dictionary)
+    const dict = {}
+
+    if (type === 'Null' || type === 'Undefined') {
+      return dict
+    } else if (type !== 'Object') {
+      throw webidl.errors.exception({
+        header: 'Dictionary',
+        message: `Expected ${dictionary} to be one of: Null, Undefined, Object.`
+      })
+    }
+
+    for (const options of converters) {
+      const { key, defaultValue, required, converter } = options
+
+      if (required === true) {
+        if (!hasOwn(dictionary, key)) {
+          throw webidl.errors.exception({
+            header: 'Dictionary',
+            message: `Missing required key "${key}".`
+          })
+        }
+      }
+
+      let value = dictionary[key]
+      const hasDefault = hasOwn(options, 'defaultValue')
+
+      // Only use defaultValue if value is undefined and
+      // a defaultValue options was provided.
+      if (hasDefault && value !== null) {
+        value = value ?? defaultValue
+      }
+
+      // A key can be optional and have no default value.
+      // When this happens, do not perform a conversion,
+      // and do not assign the key a value.
+      if (required || hasDefault || value !== undefined) {
+        value = converter(value)
+
+        if (
+          options.allowedValues &&
+          !options.allowedValues.includes(value)
+        ) {
+          throw webidl.errors.exception({
+            header: 'Dictionary',
+            message: `${value} is not an accepted type. Expected one of ${options.allowedValues.join(', ')}.`
+          })
+        }
+
+        dict[key] = value
+      }
+    }
+
+    return dict
+  }
+}
+
+webidl.nullableConverter = function (converter) {
+  return (V) => {
+    if (V === null) {
+      return V
+    }
+
+    return converter(V)
+  }
+}
+
+// https://webidl.spec.whatwg.org/#es-DOMString
+webidl.converters.DOMString = function (V, opts = {}) {
+  // 1. If V is null and the conversion is to an IDL type
+  //    associated with the [LegacyNullToEmptyString]
+  //    extended attribute, then return the DOMString value
+  //    that represents the empty string.
+  if (V === null && opts.legacyNullToEmptyString) {
+    return ''
+  }
+
+  // 2. Let x be ? ToString(V).
+  if (typeof V === 'symbol') {
+    throw new TypeError('Could not convert argument of type symbol to string.')
+  }
+
+  // 3. Return the IDL DOMString value that represents the
+  //    same sequence of code units as the one the
+  //    ECMAScript String value x represents.
+  return String(V)
+}
+
+// https://webidl.spec.whatwg.org/#es-ByteString
+webidl.converters.ByteString = function (V) {
+  // 1. Let x be ? ToString(V).
+  // Note: DOMString converter perform ? ToString(V)
+  const x = webidl.converters.DOMString(V)
+
+  // 2. If the value of any element of x is greater than
+  //    255, then throw a TypeError.
+  for (let index = 0; index < x.length; index++) {
+    if (x.charCodeAt(index) > 255) {
+      throw new TypeError(
+        'Cannot convert argument to a ByteString because the character at ' +
+        `index ${index} has a value of ${x.charCodeAt(index)} which is greater than 255.`
+      )
+    }
+  }
+
+  // 3. Return an IDL ByteString value whose length is the
+  //    length of x, and where the value of each element is
+  //    the value of the corresponding element of x.
+  return x
+}
+
+// https://webidl.spec.whatwg.org/#es-USVString
+webidl.converters.USVString = toUSVString
+
+// https://webidl.spec.whatwg.org/#es-boolean
+webidl.converters.boolean = function (V) {
+  // 1. Let x be the result of computing ToBoolean(V).
+  const x = Boolean(V)
+
+  // 2. Return the IDL boolean value that is the one that represents
+  //    the same truth value as the ECMAScript Boolean value x.
+  return x
+}
+
+// https://webidl.spec.whatwg.org/#es-any
+webidl.converters.any = function (V) {
+  return V
+}
+
+// https://webidl.spec.whatwg.org/#es-long-long
+webidl.converters['long long'] = function (V) {
+  // 1. Let x be ? ConvertToInt(V, 64, "signed").
+  const x = webidl.util.ConvertToInt(V, 64, 'signed')
+
+  // 2. Return the IDL long long value that represents
+  //    the same numeric value as x.
+  return x
+}
+
+// https://webidl.spec.whatwg.org/#es-unsigned-long-long
+webidl.converters['unsigned long long'] = function (V) {
+  // 1. Let x be ? ConvertToInt(V, 64, "unsigned").
+  const x = webidl.util.ConvertToInt(V, 64, 'unsigned')
+
+  // 2. Return the IDL unsigned long long value that
+  //    represents the same numeric value as x.
+  return x
+}
+
+// https://webidl.spec.whatwg.org/#es-unsigned-long
+webidl.converters['unsigned long'] = function (V) {
+  // 1. Let x be ? ConvertToInt(V, 32, "unsigned").
+  const x = webidl.util.ConvertToInt(V, 32, 'unsigned')
+
+  // 2. Return the IDL unsigned long value that
+  //    represents the same numeric value as x.
+  return x
+}
+
+// https://webidl.spec.whatwg.org/#es-unsigned-short
+webidl.converters['unsigned short'] = function (V, opts) {
+  // 1. Let x be ? ConvertToInt(V, 16, "unsigned").
+  const x = webidl.util.ConvertToInt(V, 16, 'unsigned', opts)
+
+  // 2. Return the IDL unsigned short value that represents
+  //    the same numeric value as x.
+  return x
+}
+
+// https://webidl.spec.whatwg.org/#idl-ArrayBuffer
+webidl.converters.ArrayBuffer = function (V, opts = {}) {
+  // 1. If Type(V) is not Object, or V does not have an
+  //    [[ArrayBufferData]] internal slot, then throw a
+  //    TypeError.
+  // see: https://tc39.es/ecma262/#sec-properties-of-the-arraybuffer-instances
+  // see: https://tc39.es/ecma262/#sec-properties-of-the-sharedarraybuffer-instances
+  if (
+    webidl.util.Type(V) !== 'Object' ||
+    !types.isAnyArrayBuffer(V)
+  ) {
+    throw webidl.errors.conversionFailed({
+      prefix: `${V}`,
+      argument: `${V}`,
+      types: ['ArrayBuffer']
+    })
+  }
+
+  // 2. If the conversion is not to an IDL type associated
+  //    with the [AllowShared] extended attribute, and
+  //    IsSharedArrayBuffer(V) is true, then throw a
+  //    TypeError.
+  if (opts.allowShared === false && types.isSharedArrayBuffer(V)) {
+    throw webidl.errors.exception({
+      header: 'ArrayBuffer',
+      message: 'SharedArrayBuffer is not allowed.'
+    })
+  }
+
+  // 3. If the conversion is not to an IDL type associated
+  //    with the [AllowResizable] extended attribute, and
+  //    IsResizableArrayBuffer(V) is true, then throw a
+  //    TypeError.
+  // Note: resizable ArrayBuffers are currently a proposal.
+
+  // 4. Return the IDL ArrayBuffer value that is a
+  //    reference to the same object as V.
+  return V
+}
+
+webidl.converters.TypedArray = function (V, T, opts = {}) {
+  // 1. Let T be the IDL type V is being converted to.
+
+  // 2. If Type(V) is not Object, or V does not have a
+  //    [[TypedArrayName]] internal slot with a value
+  //    equal to T’s name, then throw a TypeError.
+  if (
+    webidl.util.Type(V) !== 'Object' ||
+    !types.isTypedArray(V) ||
+    V.constructor.name !== T.name
+  ) {
+    throw webidl.errors.conversionFailed({
+      prefix: `${T.name}`,
+      argument: `${V}`,
+      types: [T.name]
+    })
+  }
+
+  // 3. If the conversion is not to an IDL type associated
+  //    with the [AllowShared] extended attribute, and
+  //    IsSharedArrayBuffer(V.[[ViewedArrayBuffer]]) is
+  //    true, then throw a TypeError.
+  if (opts.allowShared === false && types.isSharedArrayBuffer(V.buffer)) {
+    throw webidl.errors.exception({
+      header: 'ArrayBuffer',
+      message: 'SharedArrayBuffer is not allowed.'
+    })
+  }
+
+  // 4. If the conversion is not to an IDL type associated
+  //    with the [AllowResizable] extended attribute, and
+  //    IsResizableArrayBuffer(V.[[ViewedArrayBuffer]]) is
+  //    true, then throw a TypeError.
+  // Note: resizable array buffers are currently a proposal
+
+  // 5. Return the IDL value of type T that is a reference
+  //    to the same object as V.
+  return V
+}
+
+webidl.converters.DataView = function (V, opts = {}) {
+  // 1. If Type(V) is not Object, or V does not have a
+  //    [[DataView]] internal slot, then throw a TypeError.
+  if (webidl.util.Type(V) !== 'Object' || !types.isDataView(V)) {
+    throw webidl.errors.exception({
+      header: 'DataView',
+      message: 'Object is not a DataView.'
+    })
+  }
+
+  // 2. If the conversion is not to an IDL type associated
+  //    with the [AllowShared] extended attribute, and
+  //    IsSharedArrayBuffer(V.[[ViewedArrayBuffer]]) is true,
+  //    then throw a TypeError.
+  if (opts.allowShared === false && types.isSharedArrayBuffer(V.buffer)) {
+    throw webidl.errors.exception({
+      header: 'ArrayBuffer',
+      message: 'SharedArrayBuffer is not allowed.'
+    })
+  }
+
+  // 3. If the conversion is not to an IDL type associated
+  //    with the [AllowResizable] extended attribute, and
+  //    IsResizableArrayBuffer(V.[[ViewedArrayBuffer]]) is
+  //    true, then throw a TypeError.
+  // Note: resizable ArrayBuffers are currently a proposal
+
+  // 4. Return the IDL DataView value that is a reference
+  //    to the same object as V.
+  return V
+}
+
+// https://webidl.spec.whatwg.org/#BufferSource
+webidl.converters.BufferSource = function (V, opts = {}) {
+  if (types.isAnyArrayBuffer(V)) {
+    return webidl.converters.ArrayBuffer(V, opts)
+  }
+
+  if (types.isTypedArray(V)) {
+    return webidl.converters.TypedArray(V, V.constructor)
+  }
+
+  if (types.isDataView(V)) {
+    return webidl.converters.DataView(V, opts)
+  }
+
+  throw new TypeError(`Could not convert ${V} to a BufferSource.`)
+}
+
+webidl.converters['sequence<ByteString>'] = webidl.sequenceConverter(
+  webidl.converters.ByteString
+)
+
+webidl.converters['sequence<sequence<ByteString>>'] = webidl.sequenceConverter(
+  webidl.converters['sequence<ByteString>']
+)
+
+webidl.converters['record<ByteString, ByteString>'] = webidl.recordConverter(
+  webidl.converters.ByteString,
+  webidl.converters.ByteString
+)
+
+module.exports = {
+  webidl
+}