4 files changed, 1022 insertions, 0 deletions
diff --git a/third_party/rust/bhttp/src/err.rs b/third_party/rust/bhttp/src/err.rs
new file mode 100644
index 0000000000..5ee136f960
--- /dev/null
+++ b/third_party/rust/bhttp/src/err.rs
@@ -0,0 +1,38 @@
+use thiserror::Error;
+
+#[derive(Error, Debug)]
+pub enum Error {
+    #[error("a request used the CONNECT method")]
+    ConnectUnsupported,
+    #[error("a field contained invalid Unicode: {0}")]
+    CharacterEncoding(#[from] std::string::FromUtf8Error),
+    #[error("a field contained an integer value that was out of range: {0}")]
+    IntRange(#[from] std::num::TryFromIntError),
+    #[error("the mode of the message was invalid")]
+    InvalidMode,
+    #[error("IO error {0}")]
+    Io(#[from] std::io::Error),
+    #[error("a field or line was missing a necessary character 0x{0:x}")]
+    Missing(u8),
+    #[error("a URL was missing a key component")]
+    MissingUrlComponent,
+    #[error("an obs-fold line was the first line of a field section")]
+    ObsFold,
+    #[error("a field contained a non-integer value: {0}")]
+    ParseInt(#[from] std::num::ParseIntError),
+    #[error("a field was truncated")]
+    Truncated,
+    #[error("a message included the Upgrade field")]
+    UpgradeUnsupported,
+    #[error("a URL could not be parsed into components: {0}")]
+    #[cfg(feature = "read-http")]
+    UrlParse(#[from] url::ParseError),
+}
+
+#[cfg(any(
+    feature = "read-http",
+    feature = "write-http",
+    feature = "read-bhttp",
+    feature = "write-bhttp"
+))]
+pub type Res<T> = Result<T, Error>;
diff --git a/third_party/rust/bhttp/src/lib.rs b/third_party/rust/bhttp/src/lib.rs
new file mode 100644
index 0000000000..205cbf7202
--- /dev/null
+++ b/third_party/rust/bhttp/src/lib.rs
@@ -0,0 +1,797 @@
+#![deny(warnings, clippy::pedantic)]
+#![allow(clippy::missing_errors_doc)] // Too lazy to document these.
+
+#[cfg(feature = "read-bhttp")]
+use std::convert::TryFrom;
+#[cfg(any(
+    feature = "read-http",
+    feature = "write-http",
+    feature = "read-bhttp",
+    feature = "write-bhttp"
+))]
+use std::io;
+#[cfg(feature = "read-http")]
+use url::Url;
+
+mod err;
+mod parse;
+#[cfg(any(feature = "read-bhttp", feature = "write-bhttp"))]
+mod rw;
+
+pub use err::Error;
+#[cfg(any(
+    feature = "read-http",
+    feature = "write-http",
+    feature = "read-bhttp",
+    feature = "write-bhttp"
+))]
+use err::Res;
+#[cfg(feature = "read-http")]
+use parse::{downcase, is_ows, read_line, split_at, COLON, SEMICOLON, SLASH, SP};
+use parse::{index_of, trim_ows, COMMA};
+#[cfg(feature = "read-bhttp")]
+use rw::{read_varint, read_vec};
+#[cfg(feature = "write-bhttp")]
+use rw::{write_len, write_varint, write_vec};
+#[cfg(any(feature = "read-http", feature = "read-bhttp",))]
+use std::borrow::BorrowMut;
+
+#[cfg(feature = "read-http")]
+const CONTENT_LENGTH: &[u8] = b"content-length";
+#[cfg(feature = "read-bhttp")]
+const COOKIE: &[u8] = b"cookie";
+const TRANSFER_ENCODING: &[u8] = b"transfer-encoding";
+const CHUNKED: &[u8] = b"chunked";
+
+pub type StatusCode = u16;
+
+pub trait ReadSeek: io::BufRead + io::Seek {}
+impl<T> ReadSeek for io::Cursor<T> where T: AsRef<[u8]> {}
+impl<T> ReadSeek for io::BufReader<T> where T: io::Read + io::Seek {}
+
+#[derive(Clone, Copy, Debug, PartialEq, Eq)]
+#[cfg(any(feature = "read-bhttp", feature = "write-bhttp"))]
+pub enum Mode {
+    KnownLength,
+    IndefiniteLength,
+}
+
+pub struct Field {
+    name: Vec<u8>,
+    value: Vec<u8>,
+}
+
+impl Field {
+    #[must_use]
+    pub fn new(name: Vec<u8>, value: Vec<u8>) -> Self {
+        Self { name, value }
+    }
+
+    #[must_use]
+    pub fn name(&self) -> &[u8] {
+        &self.name
+    }
+
+    #[must_use]
+    pub fn value(&self) -> &[u8] {
+        &self.value
+    }
+
+    #[cfg(feature = "write-http")]
+    pub fn write_http(&self, w: &mut impl io::Write) -> Res<()> {
+        w.write_all(&self.name)?;
+        w.write_all(b": ")?;
+        w.write_all(&self.value)?;
+        w.write_all(b"\r\n")?;
+        Ok(())
+    }
+
+    #[cfg(feature = "write-bhttp")]
+    pub fn write_bhttp(&self, w: &mut impl io::Write) -> Res<()> {
+        write_vec(&self.name, w)?;
+        write_vec(&self.value, w)?;
+        Ok(())
+    }
+
+    #[cfg(feature = "read-http")]
+    pub fn obs_fold(&mut self, extra: &[u8]) {
+        self.value.push(SP);
+        self.value.extend(trim_ows(extra));
+    }
+}
+
+#[derive(Default)]
+pub struct FieldSection(Vec<Field>);
+impl FieldSection {
+    #[must_use]
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+
+    /// Gets the value from the first instance of the field.
+    #[must_use]
+    pub fn get(&self, n: &[u8]) -> Option<&[u8]> {
+        for f in &self.0 {
+            if &f.name[..] == n {
+                return Some(&f.value);
+            }
+        }
+        None
+    }
+
+    pub fn put(&mut self, name: impl Into<Vec<u8>>, value: impl Into<Vec<u8>>) {
+        self.0.push(Field::new(name.into(), value.into()));
+    }
+
+    pub fn iter(&self) -> impl Iterator<Item = &Field> {
+        self.0.iter()
+    }
+
+    #[must_use]
+    pub fn fields(&self) -> &[Field] {
+        &self.0
+    }
+
+    #[must_use]
+    pub fn is_chunked(&self) -> bool {
+        // Look at the last symbol in Transfer-Encoding.
+        // This is very primitive decoding; structured field this is not.
+        if let Some(te) = self.get(TRANSFER_ENCODING) {
+            let mut slc = te;
+            while let Some(i) = index_of(COMMA, slc) {
+                slc = trim_ows(&slc[i + 1..]);
+            }
+            slc == CHUNKED
+        } else {
+            false
+        }
+    }
+
+    /// As required by the HTTP specification, remove the Connection header
+    /// field, everything it refers to, and a few extra fields.
+    #[cfg(feature = "read-http")]
+    fn strip_connection_headers(&mut self) {
+        const CONNECTION: &[u8] = b"connection";
+        const PROXY_CONNECTION: &[u8] = b"proxy-connection";
+        const SHOULD_REMOVE: &[&[u8]] = &[
+            CONNECTION,
+            PROXY_CONNECTION,
+            b"keep-alive",
+            b"te",
+            b"trailer",
+            b"transfer-encoding",
+            b"upgrade",
+        ];
+        let mut listed = Vec::new();
+        let mut track = |n| {
+            let mut name = Vec::from(trim_ows(n));
+            downcase(&mut name);
+            if !listed.contains(&name) {
+                listed.push(name);
+            }
+        };
+
+        for f in self
+            .0
+            .iter()
+            .filter(|f| f.name() == CONNECTION || f.name == PROXY_CONNECTION)
+        {
+            let mut v = f.value();
+            while let Some(i) = index_of(COMMA, v) {
+                track(&v[..i]);
+                v = &v[i + 1..];
+            }
+            track(v);
+        }
+
+        self.0.retain(|f| {
+            !SHOULD_REMOVE.contains(&f.name()) && listed.iter().all(|x| &x[..] != f.name())
+        });
+    }
+
+    #[cfg(feature = "read-http")]
+    fn parse_line(fields: &mut Vec<Field>, line: Vec<u8>) -> Res<()> {
+        // obs-fold is helpful in specs, so support it here too
+        let f = if is_ows(line[0]) {
+            let mut e = fields.pop().ok_or(Error::ObsFold)?;
+            e.obs_fold(&line);
+            e
+        } else if let Some((n, v)) = split_at(COLON, line) {
+            let mut name = Vec::from(trim_ows(&n));
+            downcase(&mut name);
+            let value = Vec::from(trim_ows(&v));
+            Field::new(name, value)
+        } else {
+            return Err(Error::Missing(COLON));
+        };
+        fields.push(f);
+        Ok(())
+    }
+
+    #[cfg(feature = "read-http")]
+    pub fn read_http<T, R>(r: &mut T) -> Res<Self>
+    where
+        T: BorrowMut<R> + ?Sized,
+        R: ReadSeek + ?Sized,
+    {
+        let mut fields = Vec::new();
+        loop {
+            let line = read_line(r)?;
+            if trim_ows(&line).is_empty() {
+                return Ok(Self(fields));
+            }
+            Self::parse_line(&mut fields, line)?;
+        }
+    }
+
+    #[cfg(feature = "read-bhttp")]
+    fn read_bhttp_fields<T, R>(terminator: bool, r: &mut T) -> Res<Vec<Field>>
+    where
+        T: BorrowMut<R> + ?Sized,
+        R: ReadSeek + ?Sized,
+    {
+        let r = r.borrow_mut();
+        let mut fields = Vec::new();
+        let mut cookie_index: Option<usize> = None;
+        loop {
+            if let Some(n) = read_vec(r)? {
+                if n.is_empty() {
+                    if terminator {
+                        return Ok(fields);
+                    }
+                    return Err(Error::Truncated);
+                }
+                let mut v = read_vec(r)?.ok_or(Error::Truncated)?;
+                if n == COOKIE {
+                    if let Some(i) = &cookie_index {
+                        fields[*i].value.extend_from_slice(b"; ");
+                        fields[*i].value.append(&mut v);
+                        continue;
+                    }
+                    cookie_index = Some(fields.len());
+                }
+                fields.push(Field::new(n, v));
+            } else if terminator {
+                return Err(Error::Truncated);
+            } else {
+                return Ok(fields);
+            }
+        }
+    }
+
+    #[cfg(feature = "read-bhttp")]
+    pub fn read_bhttp<T, R>(mode: Mode, r: &mut T) -> Res<Self>
+    where
+        T: BorrowMut<R> + ?Sized,
+        R: ReadSeek + ?Sized,
+    {
+        let fields = if mode == Mode::KnownLength {
+            if let Some(buf) = read_vec(r)? {
+                Self::read_bhttp_fields(false, &mut io::Cursor::new(&buf[..]))?
+            } else {
+                Vec::new()
+            }
+        } else {
+            Self::read_bhttp_fields(true, r)?
+        };
+        Ok(Self(fields))
+    }
+
+    #[cfg(feature = "write-bhttp")]
+    fn write_bhttp_headers(&self, w: &mut impl io::Write) -> Res<()> {
+        for f in &self.0 {
+            f.write_bhttp(w)?;
+        }
+        Ok(())
+    }
+
+    #[cfg(feature = "write-bhttp")]
+    pub fn write_bhttp(&self, mode: Mode, w: &mut impl io::Write) -> Res<()> {
+        if mode == Mode::KnownLength {
+            let mut buf = Vec::new();
+            self.write_bhttp_headers(&mut buf)?;
+            write_vec(&buf, w)?;
+        } else {
+            self.write_bhttp_headers(w)?;
+            write_len(0, w)?;
+        }
+        Ok(())
+    }
+
+    #[cfg(feature = "write-http")]
+    pub fn write_http(&self, w: &mut impl io::Write) -> Res<()> {
+        for f in &self.0 {
+            f.write_http(w)?;
+        }
+        w.write_all(b"\r\n")?;
+        Ok(())
+    }
+}
+
+pub enum ControlData {
+    Request {
+        method: Vec<u8>,
+        scheme: Vec<u8>,
+        authority: Vec<u8>,
+        path: Vec<u8>,
+    },
+    Response(StatusCode),
+}
+
+impl ControlData {
+    #[must_use]
+    pub fn is_request(&self) -> bool {
+        matches!(self, Self::Request { .. })
+    }
+
+    #[must_use]
+    pub fn method(&self) -> Option<&[u8]> {
+        if let Self::Request { method, .. } = self {
+            Some(method)
+        } else {
+            None
+        }
+    }
+
+    #[must_use]
+    pub fn scheme(&self) -> Option<&[u8]> {
+        if let Self::Request { scheme, .. } = self {
+            Some(scheme)
+        } else {
+            None
+        }
+    }
+
+    #[must_use]
+    pub fn authority(&self) -> Option<&[u8]> {
+        if let Self::Request { authority, .. } = self {
+            if authority.is_empty() {
+                None
+            } else {
+                Some(authority)
+            }
+        } else {
+            None
+        }
+    }
+
+    #[must_use]
+    pub fn path(&self) -> Option<&[u8]> {
+        if let Self::Request { path, .. } = self {
+            if path.is_empty() {
+                None
+            } else {
+                Some(path)
+            }
+        } else {
+            None
+        }
+    }
+
+    #[must_use]
+    pub fn status(&self) -> Option<StatusCode> {
+        if let Self::Response(code) = self {
+            Some(*code)
+        } else {
+            None
+        }
+    }
+
+    #[cfg(feature = "read-http")]
+    pub fn read_http(line: Vec<u8>) -> Res<Self> {
+        //  request-line = method SP request-target SP HTTP-version
+        //  status-line = HTTP-version SP status-code SP [reason-phrase]
+        let (a, r) = split_at(SP, line).ok_or(Error::Missing(SP))?;
+        let (b, _) = split_at(SP, r).ok_or(Error::Missing(SP))?;
+        if index_of(SLASH, &a).is_some() {
+            // Probably a response, so treat it as such.
+            let status_str = String::from_utf8(b)?;
+            let code = status_str.parse::<u16>()?;
+            Ok(Self::Response(code))
+        } else if index_of(COLON, &b).is_some() {
+            // Now try to parse the URL.
+            let url_str = String::from_utf8(b)?;
+            let parsed = Url::parse(&url_str)?;
+            let authority = parsed.host_str().map_or_else(String::new, |host| {
+                let mut authority = String::from(host);
+                if let Some(port) = parsed.port() {
+                    authority.push(':');
+                    authority.push_str(&port.to_string());
+                }
+                authority
+            });
+            let mut path = String::from(parsed.path());
+            if let Some(q) = parsed.query() {
+                path.push('?');
+                path.push_str(q);
+            }
+            Ok(Self::Request {
+                method: a,
+                scheme: Vec::from(parsed.scheme().as_bytes()),
+                authority: Vec::from(authority.as_bytes()),
+                path: Vec::from(path.as_bytes()),
+            })
+        } else {
+            if a == b"CONNECT" {
+                return Err(Error::ConnectUnsupported);
+            }
+            Ok(Self::Request {
+                method: a,
+                scheme: Vec::from(&b"https"[..]),
+                authority: Vec::new(),
+                path: b,
+            })
+        }
+    }
+
+    #[cfg(feature = "read-bhttp")]
+    pub fn read_bhttp<T, R>(request: bool, r: &mut T) -> Res<Self>
+    where
+        T: BorrowMut<R> + ?Sized,
+        R: ReadSeek + ?Sized,
+    {
+        let v = if request {
+            let method = read_vec(r)?.ok_or(Error::Truncated)?;
+            let scheme = read_vec(r)?.ok_or(Error::Truncated)?;
+            let authority = read_vec(r)?.ok_or(Error::Truncated)?;
+            let path = read_vec(r)?.ok_or(Error::Truncated)?;
+            Self::Request {
+                method,
+                scheme,
+                authority,
+                path,
+            }
+        } else {
+            Self::Response(u16::try_from(read_varint(r)?.ok_or(Error::Truncated)?)?)
+        };
+        Ok(v)
+    }
+
+    /// If this is an informational response.
+    #[cfg(any(feature = "read-bhttp", feature = "read-http"))]
+    #[must_use]
+    fn informational(&self) -> Option<StatusCode> {
+        match self {
+            Self::Response(v) if *v >= 100 && *v < 200 => Some(*v),
+            _ => None,
+        }
+    }
+
+    #[cfg(feature = "write-bhttp")]
+    #[must_use]
+    fn code(&self, mode: Mode) -> u64 {
+        match (self, mode) {
+            (Self::Request { .. }, Mode::KnownLength) => 0,
+            (Self::Response(_), Mode::KnownLength) => 1,
+            (Self::Request { .. }, Mode::IndefiniteLength) => 2,
+            (Self::Response(_), Mode::IndefiniteLength) => 3,
+        }
+    }
+
+    #[cfg(feature = "write-bhttp")]
+    pub fn write_bhttp(&self, w: &mut impl io::Write) -> Res<()> {
+        match self {
+            Self::Request {
+                method,
+                scheme,
+                authority,
+                path,
+            } => {
+                write_vec(method, w)?;
+                write_vec(scheme, w)?;
+                write_vec(authority, w)?;
+                write_vec(path, w)?;
+            }
+            Self::Response(status) => write_varint(*status, w)?,
+        }
+        Ok(())
+    }
+
+    #[cfg(feature = "write-http")]
+    pub fn write_http(&self, w: &mut impl io::Write) -> Res<()> {
+        match self {
+            Self::Request {
+                method,
+                scheme,
+                authority,
+                path,
+            } => {
+                w.write_all(method)?;
+                w.write_all(b" ")?;
+                if !authority.is_empty() {
+                    w.write_all(scheme)?;
+                    w.write_all(b"://")?;
+                    w.write_all(authority)?;
+                }
+                w.write_all(path)?;
+                w.write_all(b" HTTP/1.1\r\n")?;
+            }
+            Self::Response(status) => {
+                let buf = format!("HTTP/1.1 {} Reason\r\n", *status);
+                w.write_all(buf.as_bytes())?;
+            }
+        }
+        Ok(())
+    }
+}
+
+pub struct InformationalResponse {
+    status: StatusCode,
+    fields: FieldSection,
+}
+
+impl InformationalResponse {
+    #[must_use]
+    pub fn new(status: StatusCode, fields: FieldSection) -> Self {
+        Self { status, fields }
+    }
+
+    #[must_use]
+    pub fn status(&self) -> StatusCode {
+        self.status
+    }
+
+    #[must_use]
+    pub fn fields(&self) -> &FieldSection {
+        &self.fields
+    }
+
+    #[cfg(feature = "write-bhttp")]
+    fn write_bhttp(&self, mode: Mode, w: &mut impl io::Write) -> Res<()> {
+        write_varint(self.status, w)?;
+        self.fields.write_bhttp(mode, w)?;
+        Ok(())
+    }
+}
+
+pub struct Message {
+    informational: Vec<InformationalResponse>,
+    control: ControlData,
+    header: FieldSection,
+    content: Vec<u8>,
+    trailer: FieldSection,
+}
+
+impl Message {
+    #[must_use]
+    pub fn request(method: Vec<u8>, scheme: Vec<u8>, authority: Vec<u8>, path: Vec<u8>) -> Self {
+        Self {
+            informational: Vec::new(),
+            control: ControlData::Request {
+                method,
+                scheme,
+                authority,
+                path,
+            },
+            header: FieldSection::default(),
+            content: Vec::new(),
+            trailer: FieldSection::default(),
+        }
+    }
+
+    #[must_use]
+    pub fn response(status: StatusCode) -> Self {
+        Self {
+            informational: Vec::new(),
+            control: ControlData::Response(status),
+            header: FieldSection::default(),
+            content: Vec::new(),
+            trailer: FieldSection::default(),
+        }
+    }
+
+    pub fn put_header(&mut self, name: impl Into<Vec<u8>>, value: impl Into<Vec<u8>>) {
+        self.header.put(name, value);
+    }
+
+    pub fn put_trailer(&mut self, name: impl Into<Vec<u8>>, value: impl Into<Vec<u8>>) {
+        self.trailer.put(name, value);
+    }
+
+    pub fn write_content(&mut self, d: impl AsRef<[u8]>) {
+        self.content.extend_from_slice(d.as_ref());
+    }
+
+    #[must_use]
+    pub fn informational(&self) -> &[InformationalResponse] {
+        &self.informational
+    }
+
+    #[must_use]
+    pub fn control(&self) -> &ControlData {
+        &self.control
+    }
+
+    #[must_use]
+    pub fn header(&self) -> &FieldSection {
+        &self.header
+    }
+
+    #[must_use]
+    pub fn content(&self) -> &[u8] {
+        &self.content
+    }
+
+    #[must_use]
+    pub fn trailer(&self) -> &FieldSection {
+        &self.trailer
+    }
+
+    #[cfg(feature = "read-http")]
+    fn read_chunked<T, R>(r: &mut T) -> Res<Vec<u8>>
+    where
+        T: BorrowMut<R> + ?Sized,
+        R: ReadSeek + ?Sized,
+    {
+        let mut content = Vec::new();
+        loop {
+            let mut line = read_line(r)?;
+            if let Some(i) = index_of(SEMICOLON, &line) {
+                std::mem::drop(line.split_off(i));
+            }
+            let count_str = String::from_utf8(line)?;
+            let count = usize::from_str_radix(&count_str, 16)?;
+            if count == 0 {
+                return Ok(content);
+            }
+            let mut buf = vec![0; count];
+            r.borrow_mut().read_exact(&mut buf)?;
+            assert!(read_line(r)?.is_empty());
+            content.append(&mut buf);
+        }
+    }
+
+    #[cfg(feature = "read-http")]
+    #[allow(clippy::read_zero_byte_vec)] // https://github.com/rust-lang/rust-clippy/issues/9274
+    pub fn read_http<T, R>(r: &mut T) -> Res<Self>
+    where
+        T: BorrowMut<R> + ?Sized,
+        R: ReadSeek + ?Sized,
+    {
+        let line = read_line(r)?;
+        let mut control = ControlData::read_http(line)?;
+        let mut informational = Vec::new();
+        while let Some(status) = control.informational() {
+            let fields = FieldSection::read_http(r)?;
+            informational.push(InformationalResponse::new(status, fields));
+            let line = read_line(r)?;
+            control = ControlData::read_http(line)?;
+        }
+
+        let mut header = FieldSection::read_http(r)?;
+
+        let (content, trailer) = if matches!(control.status(), Some(204) | Some(304)) {
+            // 204 and 304 have no body, no matter what Content-Length says.
+            // Unfortunately, we can't do the same for responses to HEAD.
+            (Vec::new(), FieldSection::default())
+        } else if header.is_chunked() {
+            let content = Self::read_chunked(r)?;
+            let trailer = FieldSection::read_http(r)?;
+            (content, trailer)
+        } else {
+            let mut content = Vec::new();
+            if let Some(cl) = header.get(CONTENT_LENGTH) {
+                let cl_str = String::from_utf8(Vec::from(cl))?;
+                let cl_int = cl_str.parse::<usize>()?;
+                if cl_int > 0 {
+                    content.resize(cl_int, 0);
+                    r.borrow_mut().read_exact(&mut content)?;
+                }
+            } else {
+                // Note that for a request, the spec states that the content is
+                // empty, but this just reads all input like for a response.
+                r.borrow_mut().read_to_end(&mut content)?;
+            }
+            (content, FieldSection::default())
+        };
+
+        header.strip_connection_headers();
+        Ok(Self {
+            informational,
+            control,
+            header,
+            content,
+            trailer,
+        })
+    }
+
+    #[cfg(feature = "write-http")]
+    pub fn write_http(&self, w: &mut impl io::Write) -> Res<()> {
+        for info in &self.informational {
+            ControlData::Response(info.status()).write_http(w)?;
+            info.fields().write_http(w)?;
+        }
+        self.control.write_http(w)?;
+        if !self.content.is_empty() {
+            if self.trailer.is_empty() {
+                write!(w, "Content-Length: {}\r\n", self.content.len())?;
+            } else {
+                w.write_all(b"Transfer-Encoding: chunked\r\n")?;
+            }
+        }
+        self.header.write_http(w)?;
+
+        if self.header.is_chunked() {
+            write!(w, "{:x}\r\n", self.content.len())?;
+            w.write_all(&self.content)?;
+            w.write_all(b"\r\n0\r\n")?;
+            self.trailer.write_http(w)?;
+        } else {
+            w.write_all(&self.content)?;
+        }
+
+        Ok(())
+    }
+
+    /// Read a BHTTP message.
+    #[cfg(feature = "read-bhttp")]
+    pub fn read_bhttp<T, R>(r: &mut T) -> Res<Self>
+    where
+        T: BorrowMut<R> + ?Sized,
+        R: ReadSeek + ?Sized,
+    {
+        let t = read_varint(r)?.ok_or(Error::Truncated)?;
+        let request = t == 0 || t == 2;
+        let mode = match t {
+            0 | 1 => Mode::KnownLength,
+            2 | 3 => Mode::IndefiniteLength,
+            _ => return Err(Error::InvalidMode),
+        };
+
+        let mut control = ControlData::read_bhttp(request, r)?;
+        let mut informational = Vec::new();
+        while let Some(status) = control.informational() {
+            let fields = FieldSection::read_bhttp(mode, r)?;
+            informational.push(InformationalResponse::new(status, fields));
+            control = ControlData::read_bhttp(request, r)?;
+        }
+        let header = FieldSection::read_bhttp(mode, r)?;
+
+        let mut content = read_vec(r)?.unwrap_or_default();
+        if mode == Mode::IndefiniteLength && !content.is_empty() {
+            loop {
+                let mut extra = read_vec(r)?.unwrap_or_default();
+                if extra.is_empty() {
+                    break;
+                }
+                content.append(&mut extra);
+            }
+        }
+
+        let trailer = FieldSection::read_bhttp(mode, r)?;
+
+        Ok(Self {
+            informational,
+            control,
+            header,
+            content,
+            trailer,
+        })
+    }
+
+    #[cfg(feature = "write-bhttp")]
+    pub fn write_bhttp(&self, mode: Mode, w: &mut impl io::Write) -> Res<()> {
+        write_varint(self.control.code(mode), w)?;
+        for info in &self.informational {
+            info.write_bhttp(mode, w)?;
+        }
+        self.control.write_bhttp(w)?;
+        self.header.write_bhttp(mode, w)?;
+
+        write_vec(&self.content, w)?;
+        if mode == Mode::IndefiniteLength && !self.content.is_empty() {
+            write_len(0, w)?;
+        }
+        self.trailer.write_bhttp(mode, w)?;
+        Ok(())
+    }
+}
+
+#[cfg(feature = "write-http")]
+impl std::fmt::Debug for Message {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> Result<(), std::fmt::Error> {
+        let mut buf = Vec::new();
+        self.write_http(&mut buf).map_err(|_| std::fmt::Error)?;
+        write!(f, "{:?}", String::from_utf8_lossy(&buf))
+    }
+}
diff --git a/third_party/rust/bhttp/src/parse.rs b/third_party/rust/bhttp/src/parse.rs
new file mode 100644
index 0000000000..42ba2b8b01
--- /dev/null
+++ b/third_party/rust/bhttp/src/parse.rs
@@ -0,0 +1,81 @@
+#[cfg(feature = "read-http")]
+use crate::{Error, ReadSeek, Res};
+#[cfg(feature = "read-http")]
+use std::borrow::BorrowMut;
+
+pub const HTAB: u8 = 0x09;
+#[cfg(feature = "read-http")]
+pub const NL: u8 = 0x0a;
+#[cfg(feature = "read-http")]
+pub const CR: u8 = 0x0d;
+pub const SP: u8 = 0x20;
+pub const COMMA: u8 = 0x2c;
+#[cfg(feature = "read-http")]
+pub const SLASH: u8 = 0x2f;
+#[cfg(feature = "read-http")]
+pub const COLON: u8 = 0x3a;
+#[cfg(feature = "read-http")]
+pub const SEMICOLON: u8 = 0x3b;
+
+pub fn is_ows(x: u8) -> bool {
+    x == SP || x == HTAB
+}
+
+pub fn trim_ows(v: &[u8]) -> &[u8] {
+    for s in 0..v.len() {
+        if !is_ows(v[s]) {
+            for e in (s..v.len()).rev() {
+                if !is_ows(v[e]) {
+                    return &v[s..=e];
+                }
+            }
+        }
+    }
+    &v[..0]
+}
+
+#[cfg(feature = "read-http")]
+pub fn downcase(n: &mut [u8]) {
+    for i in n {
+        if *i >= 0x41 && *i <= 0x5a {
+            *i += 0x20;
+        }
+    }
+}
+
+pub fn index_of(v: u8, line: &[u8]) -> Option<usize> {
+    for (i, x) in line.iter().enumerate() {
+        if *x == v {
+            return Some(i);
+        }
+    }
+    None
+}
+
+#[cfg(feature = "read-http")]
+pub fn split_at(v: u8, mut line: Vec<u8>) -> Option<(Vec<u8>, Vec<u8>)> {
+    index_of(v, &line).map(|i| {
+        let tail = line.split_off(i + 1);
+        let _ = line.pop();
+        (line, tail)
+    })
+}
+
+#[cfg(feature = "read-http")]
+pub fn read_line<T, R>(r: &mut T) -> Res<Vec<u8>>
+where
+    T: BorrowMut<R> + ?Sized,
+    R: ReadSeek + ?Sized,
+{
+    let mut buf = Vec::new();
+    r.borrow_mut().read_until(NL, &mut buf)?;
+    let tail = buf.pop();
+    if tail != Some(NL) {
+        return Err(Error::Truncated);
+    }
+    if buf.pop().ok_or(Error::Missing(CR))? == CR {
+        Ok(buf)
+    } else {
+        Err(Error::Missing(CR))
+    }
+}
diff --git a/third_party/rust/bhttp/src/rw.rs b/third_party/rust/bhttp/src/rw.rs
new file mode 100644
index 0000000000..8fee16daa9
--- /dev/null
+++ b/third_party/rust/bhttp/src/rw.rs
@@ -0,0 +1,106 @@
+use crate::err::Res;
+#[cfg(feature = "read-bhttp")]
+use crate::{err::Error, ReadSeek};
+#[cfg(feature = "read-bhttp")]
+use std::borrow::BorrowMut;
+use std::{convert::TryFrom, io};
+
+#[cfg(feature = "write-bhttp")]
+#[allow(clippy::cast_possible_truncation)]
+fn write_uint(n: u8, v: impl Into<u64>, w: &mut impl io::Write) -> Res<()> {
+    let v = v.into();
+    assert!(n > 0 && usize::from(n) < std::mem::size_of::<u64>());
+    for i in 0..n {
+        w.write_all(&[((v >> (8 * (n - i - 1))) & 0xff) as u8])?;
+    }
+    Ok(())
+}
+
+#[cfg(feature = "write-bhttp")]
+pub fn write_varint(v: impl Into<u64>, w: &mut impl io::Write) -> Res<()> {
+    let v = v.into();
+    match () {
+        _ if v < (1 << 6) => write_uint(1, v, w),
+        _ if v < (1 << 14) => write_uint(2, v | (1 << 14), w),
+        _ if v < (1 << 30) => write_uint(4, v | (2 << 30), w),
+        _ if v < (1 << 62) => write_uint(8, v | (3 << 62), w),
+        _ => panic!("Varint value too large"),
+    }
+}
+
+#[cfg(feature = "write-bhttp")]
+pub fn write_len(len: usize, w: &mut impl io::Write) -> Res<()> {
+    write_varint(u64::try_from(len).unwrap(), w)
+}
+
+#[cfg(feature = "write-bhttp")]
+pub fn write_vec(v: &[u8], w: &mut impl io::Write) -> Res<()> {
+    write_len(v.len(), w)?;
+    w.write_all(v)?;
+    Ok(())
+}
+
+#[cfg(feature = "read-bhttp")]
+fn read_uint<T, R>(n: usize, r: &mut T) -> Res<Option<u64>>
+where
+    T: BorrowMut<R> + ?Sized,
+    R: ReadSeek + ?Sized,
+{
+    let mut buf = [0; 7];
+    let count = r.borrow_mut().read(&mut buf[..n])?;
+    if count == 0 {
+        return Ok(None);
+    } else if count < n {
+        return Err(Error::Truncated);
+    }
+    let mut v = 0;
+    for i in &buf[..n] {
+        v = (v << 8) | u64::from(*i);
+    }
+    Ok(Some(v))
+}
+
+#[cfg(feature = "read-bhttp")]
+pub fn read_varint<T, R>(r: &mut T) -> Res<Option<u64>>
+where
+    T: BorrowMut<R> + ?Sized,
+    R: ReadSeek + ?Sized,
+{
+    if let Some(b1) = read_uint(1, r)? {
+        Ok(Some(match b1 >> 6 {
+            0 => b1 & 0x3f,
+            1 => ((b1 & 0x3f) << 8) | read_uint(1, r)?.ok_or(Error::Truncated)?,
+            2 => ((b1 & 0x3f) << 24) | read_uint(3, r)?.ok_or(Error::Truncated)?,
+            3 => ((b1 & 0x3f) << 56) | read_uint(7, r)?.ok_or(Error::Truncated)?,
+            _ => unreachable!(),
+        }))
+    } else {
+        Ok(None)
+    }
+}
+
+#[cfg(feature = "read-bhttp")]
+pub fn read_vec<T, R>(r: &mut T) -> Res<Option<Vec<u8>>>
+where
+    T: BorrowMut<R> + ?Sized,
+    R: ReadSeek + ?Sized,
+{
+    use std::io::SeekFrom;
+
+    if let Some(len) = read_varint(r)? {
+        // Check that the input contains enough data.  Before allocating.
+        let r = r.borrow_mut();
+        let pos = r.stream_position()?;
+        let end = r.seek(SeekFrom::End(0))?;
+        if end - pos < len {
+            return Err(Error::Truncated);
+        }
+        let _ = r.seek(SeekFrom::Start(pos))?;
+
+        let mut v = vec![0; usize::try_from(len)?];
+        r.read_exact(&mut v)?;
+        Ok(Some(v))
+    } else {
+        Ok(None)
+    }
+}