Adding upstream version 124.0.1.upstream/124.0.1

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

13 files changed, 2611 insertions, 0 deletions

diff --git a/third_party/rust/h2/src/frame/data.rs b/third_party/rust/h2/src/frame/data.rs
new file mode 100644
index 0000000000..5ed3c31b50
--- /dev/null
+++ b/third_party/rust/h2/src/frame/data.rs
@@ -0,0 +1,227 @@
+use crate::frame::{util, Error, Frame, Head, Kind, StreamId};
+use bytes::{Buf, BufMut, Bytes};
+
+use std::fmt;
+
+/// Data frame
+///
+/// Data frames convey arbitrary, variable-length sequences of octets associated
+/// with a stream. One or more DATA frames are used, for instance, to carry HTTP
+/// request or response payloads.
+#[derive(Eq, PartialEq)]
+pub struct Data<T = Bytes> {
+    stream_id: StreamId,
+    data: T,
+    flags: DataFlags,
+    pad_len: Option<u8>,
+}
+
+#[derive(Copy, Clone, Default, Eq, PartialEq)]
+struct DataFlags(u8);
+
+const END_STREAM: u8 = 0x1;
+const PADDED: u8 = 0x8;
+const ALL: u8 = END_STREAM | PADDED;
+
+impl<T> Data<T> {
+    /// Creates a new DATA frame.
+    pub fn new(stream_id: StreamId, payload: T) -> Self {
+        assert!(!stream_id.is_zero());
+
+        Data {
+            stream_id,
+            data: payload,
+            flags: DataFlags::default(),
+            pad_len: None,
+        }
+    }
+
+    /// Returns the stream identifier that this frame is associated with.
+    ///
+    /// This cannot be a zero stream identifier.
+    pub fn stream_id(&self) -> StreamId {
+        self.stream_id
+    }
+
+    /// Gets the value of the `END_STREAM` flag for this frame.
+    ///
+    /// If true, this frame is the last that the endpoint will send for the
+    /// identified stream.
+    ///
+    /// Setting this flag causes the stream to enter one of the "half-closed"
+    /// states or the "closed" state (Section 5.1).
+    pub fn is_end_stream(&self) -> bool {
+        self.flags.is_end_stream()
+    }
+
+    /// Sets the value for the `END_STREAM` flag on this frame.
+    pub fn set_end_stream(&mut self, val: bool) {
+        if val {
+            self.flags.set_end_stream();
+        } else {
+            self.flags.unset_end_stream();
+        }
+    }
+
+    /// Returns whether the `PADDED` flag is set on this frame.
+    #[cfg(feature = "unstable")]
+    pub fn is_padded(&self) -> bool {
+        self.flags.is_padded()
+    }
+
+    /// Sets the value for the `PADDED` flag on this frame.
+    #[cfg(feature = "unstable")]
+    pub fn set_padded(&mut self) {
+        self.flags.set_padded();
+    }
+
+    /// Returns a reference to this frame's payload.
+    ///
+    /// This does **not** include any padding that might have been originally
+    /// included.
+    pub fn payload(&self) -> &T {
+        &self.data
+    }
+
+    /// Returns a mutable reference to this frame's payload.
+    ///
+    /// This does **not** include any padding that might have been originally
+    /// included.
+    pub fn payload_mut(&mut self) -> &mut T {
+        &mut self.data
+    }
+
+    /// Consumes `self` and returns the frame's payload.
+    ///
+    /// This does **not** include any padding that might have been originally
+    /// included.
+    pub fn into_payload(self) -> T {
+        self.data
+    }
+
+    pub(crate) fn head(&self) -> Head {
+        Head::new(Kind::Data, self.flags.into(), self.stream_id)
+    }
+
+    pub(crate) fn map<F, U>(self, f: F) -> Data<U>
+    where
+        F: FnOnce(T) -> U,
+    {
+        Data {
+            stream_id: self.stream_id,
+            data: f(self.data),
+            flags: self.flags,
+            pad_len: self.pad_len,
+        }
+    }
+}
+
+impl Data<Bytes> {
+    pub(crate) fn load(head: Head, mut payload: Bytes) -> Result<Self, Error> {
+        let flags = DataFlags::load(head.flag());
+
+        // The stream identifier must not be zero
+        if head.stream_id().is_zero() {
+            return Err(Error::InvalidStreamId);
+        }
+
+        let pad_len = if flags.is_padded() {
+            let len = util::strip_padding(&mut payload)?;
+            Some(len)
+        } else {
+            None
+        };
+
+        Ok(Data {
+            stream_id: head.stream_id(),
+            data: payload,
+            flags,
+            pad_len,
+        })
+    }
+}
+
+impl<T: Buf> Data<T> {
+    /// Encode the data frame into the `dst` buffer.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `dst` cannot contain the data frame.
+    pub(crate) fn encode_chunk<U: BufMut>(&mut self, dst: &mut U) {
+        let len = self.data.remaining();
+
+        assert!(dst.remaining_mut() >= len);
+
+        self.head().encode(len, dst);
+        dst.put(&mut self.data);
+    }
+}
+
+impl<T> From<Data<T>> for Frame<T> {
+    fn from(src: Data<T>) -> Self {
+        Frame::Data(src)
+    }
+}
+
+impl<T> fmt::Debug for Data<T> {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let mut f = fmt.debug_struct("Data");
+        f.field("stream_id", &self.stream_id);
+        if !self.flags.is_empty() {
+            f.field("flags", &self.flags);
+        }
+        if let Some(ref pad_len) = self.pad_len {
+            f.field("pad_len", pad_len);
+        }
+        // `data` bytes purposefully excluded
+        f.finish()
+    }
+}
+
+// ===== impl DataFlags =====
+
+impl DataFlags {
+    fn load(bits: u8) -> DataFlags {
+        DataFlags(bits & ALL)
+    }
+
+    fn is_empty(&self) -> bool {
+        self.0 == 0
+    }
+
+    fn is_end_stream(&self) -> bool {
+        self.0 & END_STREAM == END_STREAM
+    }
+
+    fn set_end_stream(&mut self) {
+        self.0 |= END_STREAM
+    }
+
+    fn unset_end_stream(&mut self) {
+        self.0 &= !END_STREAM
+    }
+
+    fn is_padded(&self) -> bool {
+        self.0 & PADDED == PADDED
+    }
+
+    #[cfg(feature = "unstable")]
+    fn set_padded(&mut self) {
+        self.0 |= PADDED
+    }
+}
+
+impl From<DataFlags> for u8 {
+    fn from(src: DataFlags) -> u8 {
+        src.0
+    }
+}
+
+impl fmt::Debug for DataFlags {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        util::debug_flags(fmt, self.0)
+            .flag_if(self.is_end_stream(), "END_STREAM")
+            .flag_if(self.is_padded(), "PADDED")
+            .finish()
+    }
+}
diff --git a/third_party/rust/h2/src/frame/go_away.rs b/third_party/rust/h2/src/frame/go_away.rs
new file mode 100644
index 0000000000..99330e9811
--- /dev/null
+++ b/third_party/rust/h2/src/frame/go_away.rs
@@ -0,0 +1,87 @@
+use std::fmt;
+
+use bytes::{BufMut, Bytes};
+
+use crate::frame::{self, Error, Head, Kind, Reason, StreamId};
+
+#[derive(Clone, Eq, PartialEq)]
+pub struct GoAway {
+    last_stream_id: StreamId,
+    error_code: Reason,
+    debug_data: Bytes,
+}
+
+impl GoAway {
+    pub fn new(last_stream_id: StreamId, reason: Reason) -> Self {
+        GoAway {
+            last_stream_id,
+            error_code: reason,
+            debug_data: Bytes::new(),
+        }
+    }
+
+    pub fn with_debug_data(last_stream_id: StreamId, reason: Reason, debug_data: Bytes) -> Self {
+        Self {
+            last_stream_id,
+            error_code: reason,
+            debug_data,
+        }
+    }
+
+    pub fn last_stream_id(&self) -> StreamId {
+        self.last_stream_id
+    }
+
+    pub fn reason(&self) -> Reason {
+        self.error_code
+    }
+
+    pub fn debug_data(&self) -> &Bytes {
+        &self.debug_data
+    }
+
+    pub fn load(payload: &[u8]) -> Result<GoAway, Error> {
+        if payload.len() < 8 {
+            return Err(Error::BadFrameSize);
+        }
+
+        let (last_stream_id, _) = StreamId::parse(&payload[..4]);
+        let error_code = unpack_octets_4!(payload, 4, u32);
+        let debug_data = Bytes::copy_from_slice(&payload[8..]);
+
+        Ok(GoAway {
+            last_stream_id,
+            error_code: error_code.into(),
+            debug_data,
+        })
+    }
+
+    pub fn encode<B: BufMut>(&self, dst: &mut B) {
+        tracing::trace!("encoding GO_AWAY; code={:?}", self.error_code);
+        let head = Head::new(Kind::GoAway, 0, StreamId::zero());
+        head.encode(8 + self.debug_data.len(), dst);
+        dst.put_u32(self.last_stream_id.into());
+        dst.put_u32(self.error_code.into());
+        dst.put(self.debug_data.slice(..));
+    }
+}
+
+impl<B> From<GoAway> for frame::Frame<B> {
+    fn from(src: GoAway) -> Self {
+        frame::Frame::GoAway(src)
+    }
+}
+
+impl fmt::Debug for GoAway {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let mut builder = f.debug_struct("GoAway");
+        builder.field("error_code", &self.error_code);
+        builder.field("last_stream_id", &self.last_stream_id);
+
+        if !self.debug_data.is_empty() {
+            builder.field("debug_data", &self.debug_data);
+        }
+
+        builder.finish()
+    }
+}
diff --git a/third_party/rust/h2/src/frame/head.rs b/third_party/rust/h2/src/frame/head.rs
new file mode 100644
index 0000000000..38be2f6973
--- /dev/null
+++ b/third_party/rust/h2/src/frame/head.rs
@@ -0,0 +1,94 @@
+use super::StreamId;
+
+use bytes::BufMut;
+
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub struct Head {
+    kind: Kind,
+    flag: u8,
+    stream_id: StreamId,
+}
+
+#[repr(u8)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq)]
+pub enum Kind {
+    Data = 0,
+    Headers = 1,
+    Priority = 2,
+    Reset = 3,
+    Settings = 4,
+    PushPromise = 5,
+    Ping = 6,
+    GoAway = 7,
+    WindowUpdate = 8,
+    Continuation = 9,
+    Unknown,
+}
+
+// ===== impl Head =====
+
+impl Head {
+    pub fn new(kind: Kind, flag: u8, stream_id: StreamId) -> Head {
+        Head {
+            kind,
+            flag,
+            stream_id,
+        }
+    }
+
+    /// Parse an HTTP/2 frame header
+    pub fn parse(header: &[u8]) -> Head {
+        let (stream_id, _) = StreamId::parse(&header[5..]);
+
+        Head {
+            kind: Kind::new(header[3]),
+            flag: header[4],
+            stream_id,
+        }
+    }
+
+    pub fn stream_id(&self) -> StreamId {
+        self.stream_id
+    }
+
+    pub fn kind(&self) -> Kind {
+        self.kind
+    }
+
+    pub fn flag(&self) -> u8 {
+        self.flag
+    }
+
+    pub fn encode_len(&self) -> usize {
+        super::HEADER_LEN
+    }
+
+    pub fn encode<T: BufMut>(&self, payload_len: usize, dst: &mut T) {
+        debug_assert!(self.encode_len() <= dst.remaining_mut());
+
+        dst.put_uint(payload_len as u64, 3);
+        dst.put_u8(self.kind as u8);
+        dst.put_u8(self.flag);
+        dst.put_u32(self.stream_id.into());
+    }
+}
+
+// ===== impl Kind =====
+
+impl Kind {
+    pub fn new(byte: u8) -> Kind {
+        match byte {
+            0 => Kind::Data,
+            1 => Kind::Headers,
+            2 => Kind::Priority,
+            3 => Kind::Reset,
+            4 => Kind::Settings,
+            5 => Kind::PushPromise,
+            6 => Kind::Ping,
+            7 => Kind::GoAway,
+            8 => Kind::WindowUpdate,
+            9 => Kind::Continuation,
+            _ => Kind::Unknown,
+        }
+    }
+}
diff --git a/third_party/rust/h2/src/frame/headers.rs b/third_party/rust/h2/src/frame/headers.rs
new file mode 100644
index 0000000000..9d5c8cefe8
--- /dev/null
+++ b/third_party/rust/h2/src/frame/headers.rs
@@ -0,0 +1,1042 @@
+use super::{util, StreamDependency, StreamId};
+use crate::ext::Protocol;
+use crate::frame::{Error, Frame, Head, Kind};
+use crate::hpack::{self, BytesStr};
+
+use http::header::{self, HeaderName, HeaderValue};
+use http::{uri, HeaderMap, Method, Request, StatusCode, Uri};
+
+use bytes::{BufMut, Bytes, BytesMut};
+
+use std::fmt;
+use std::io::Cursor;
+
+type EncodeBuf<'a> = bytes::buf::Limit<&'a mut BytesMut>;
+/// Header frame
+///
+/// This could be either a request or a response.
+#[derive(Eq, PartialEq)]
+pub struct Headers {
+    /// The ID of the stream with which this frame is associated.
+    stream_id: StreamId,
+
+    /// The stream dependency information, if any.
+    stream_dep: Option<StreamDependency>,
+
+    /// The header block fragment
+    header_block: HeaderBlock,
+
+    /// The associated flags
+    flags: HeadersFlag,
+}
+
+#[derive(Copy, Clone, Eq, PartialEq)]
+pub struct HeadersFlag(u8);
+
+#[derive(Eq, PartialEq)]
+pub struct PushPromise {
+    /// The ID of the stream with which this frame is associated.
+    stream_id: StreamId,
+
+    /// The ID of the stream being reserved by this PushPromise.
+    promised_id: StreamId,
+
+    /// The header block fragment
+    header_block: HeaderBlock,
+
+    /// The associated flags
+    flags: PushPromiseFlag,
+}
+
+#[derive(Copy, Clone, Eq, PartialEq)]
+pub struct PushPromiseFlag(u8);
+
+#[derive(Debug)]
+pub struct Continuation {
+    /// Stream ID of continuation frame
+    stream_id: StreamId,
+
+    header_block: EncodingHeaderBlock,
+}
+
+// TODO: These fields shouldn't be `pub`
+#[derive(Debug, Default, Eq, PartialEq)]
+pub struct Pseudo {
+    // Request
+    pub method: Option<Method>,
+    pub scheme: Option<BytesStr>,
+    pub authority: Option<BytesStr>,
+    pub path: Option<BytesStr>,
+    pub protocol: Option<Protocol>,
+
+    // Response
+    pub status: Option<StatusCode>,
+}
+
+#[derive(Debug)]
+pub struct Iter {
+    /// Pseudo headers
+    pseudo: Option<Pseudo>,
+
+    /// Header fields
+    fields: header::IntoIter<HeaderValue>,
+}
+
+#[derive(Debug, PartialEq, Eq)]
+struct HeaderBlock {
+    /// The decoded header fields
+    fields: HeaderMap,
+
+    /// Set to true if decoding went over the max header list size.
+    is_over_size: bool,
+
+    /// Pseudo headers, these are broken out as they must be sent as part of the
+    /// headers frame.
+    pseudo: Pseudo,
+}
+
+#[derive(Debug)]
+struct EncodingHeaderBlock {
+    hpack: Bytes,
+}
+
+const END_STREAM: u8 = 0x1;
+const END_HEADERS: u8 = 0x4;
+const PADDED: u8 = 0x8;
+const PRIORITY: u8 = 0x20;
+const ALL: u8 = END_STREAM | END_HEADERS | PADDED | PRIORITY;
+
+// ===== impl Headers =====
+
+impl Headers {
+    /// Create a new HEADERS frame
+    pub fn new(stream_id: StreamId, pseudo: Pseudo, fields: HeaderMap) -> Self {
+        Headers {
+            stream_id,
+            stream_dep: None,
+            header_block: HeaderBlock {
+                fields,
+                is_over_size: false,
+                pseudo,
+            },
+            flags: HeadersFlag::default(),
+        }
+    }
+
+    pub fn trailers(stream_id: StreamId, fields: HeaderMap) -> Self {
+        let mut flags = HeadersFlag::default();
+        flags.set_end_stream();
+
+        Headers {
+            stream_id,
+            stream_dep: None,
+            header_block: HeaderBlock {
+                fields,
+                is_over_size: false,
+                pseudo: Pseudo::default(),
+            },
+            flags,
+        }
+    }
+
+    /// Loads the header frame but doesn't actually do HPACK decoding.
+    ///
+    /// HPACK decoding is done in the `load_hpack` step.
+    pub fn load(head: Head, mut src: BytesMut) -> Result<(Self, BytesMut), Error> {
+        let flags = HeadersFlag(head.flag());
+        let mut pad = 0;
+
+        tracing::trace!("loading headers; flags={:?}", flags);
+
+        if head.stream_id().is_zero() {
+            return Err(Error::InvalidStreamId);
+        }
+
+        // Read the padding length
+        if flags.is_padded() {
+            if src.is_empty() {
+                return Err(Error::MalformedMessage);
+            }
+            pad = src[0] as usize;
+
+            // Drop the padding
+            let _ = src.split_to(1);
+        }
+
+        // Read the stream dependency
+        let stream_dep = if flags.is_priority() {
+            if src.len() < 5 {
+                return Err(Error::MalformedMessage);
+            }
+            let stream_dep = StreamDependency::load(&src[..5])?;
+
+            if stream_dep.dependency_id() == head.stream_id() {
+                return Err(Error::InvalidDependencyId);
+            }
+
+            // Drop the next 5 bytes
+            let _ = src.split_to(5);
+
+            Some(stream_dep)
+        } else {
+            None
+        };
+
+        if pad > 0 {
+            if pad > src.len() {
+                return Err(Error::TooMuchPadding);
+            }
+
+            let len = src.len() - pad;
+            src.truncate(len);
+        }
+
+        let headers = Headers {
+            stream_id: head.stream_id(),
+            stream_dep,
+            header_block: HeaderBlock {
+                fields: HeaderMap::new(),
+                is_over_size: false,
+                pseudo: Pseudo::default(),
+            },
+            flags,
+        };
+
+        Ok((headers, src))
+    }
+
+    pub fn load_hpack(
+        &mut self,
+        src: &mut BytesMut,
+        max_header_list_size: usize,
+        decoder: &mut hpack::Decoder,
+    ) -> Result<(), Error> {
+        self.header_block.load(src, max_header_list_size, decoder)
+    }
+
+    pub fn stream_id(&self) -> StreamId {
+        self.stream_id
+    }
+
+    pub fn is_end_headers(&self) -> bool {
+        self.flags.is_end_headers()
+    }
+
+    pub fn set_end_headers(&mut self) {
+        self.flags.set_end_headers();
+    }
+
+    pub fn is_end_stream(&self) -> bool {
+        self.flags.is_end_stream()
+    }
+
+    pub fn set_end_stream(&mut self) {
+        self.flags.set_end_stream()
+    }
+
+    pub fn is_over_size(&self) -> bool {
+        self.header_block.is_over_size
+    }
+
+    pub fn into_parts(self) -> (Pseudo, HeaderMap) {
+        (self.header_block.pseudo, self.header_block.fields)
+    }
+
+    #[cfg(feature = "unstable")]
+    pub fn pseudo_mut(&mut self) -> &mut Pseudo {
+        &mut self.header_block.pseudo
+    }
+
+    /// Whether it has status 1xx
+    pub(crate) fn is_informational(&self) -> bool {
+        self.header_block.pseudo.is_informational()
+    }
+
+    pub fn fields(&self) -> &HeaderMap {
+        &self.header_block.fields
+    }
+
+    pub fn into_fields(self) -> HeaderMap {
+        self.header_block.fields
+    }
+
+    pub fn encode(
+        self,
+        encoder: &mut hpack::Encoder,
+        dst: &mut EncodeBuf<'_>,
+    ) -> Option<Continuation> {
+        // At this point, the `is_end_headers` flag should always be set
+        debug_assert!(self.flags.is_end_headers());
+
+        // Get the HEADERS frame head
+        let head = self.head();
+
+        self.header_block
+            .into_encoding(encoder)
+            .encode(&head, dst, |_| {})
+    }
+
+    fn head(&self) -> Head {
+        Head::new(Kind::Headers, self.flags.into(), self.stream_id)
+    }
+}
+
+impl<T> From<Headers> for Frame<T> {
+    fn from(src: Headers) -> Self {
+        Frame::Headers(src)
+    }
+}
+
+impl fmt::Debug for Headers {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let mut builder = f.debug_struct("Headers");
+        builder
+            .field("stream_id", &self.stream_id)
+            .field("flags", &self.flags);
+
+        if let Some(ref protocol) = self.header_block.pseudo.protocol {
+            builder.field("protocol", protocol);
+        }
+
+        if let Some(ref dep) = self.stream_dep {
+            builder.field("stream_dep", dep);
+        }
+
+        // `fields` and `pseudo` purposefully not included
+        builder.finish()
+    }
+}
+
+// ===== util =====
+
+#[derive(Debug, PartialEq, Eq)]
+pub struct ParseU64Error;
+
+pub fn parse_u64(src: &[u8]) -> Result<u64, ParseU64Error> {
+    if src.len() > 19 {
+        // At danger for overflow...
+        return Err(ParseU64Error);
+    }
+
+    let mut ret = 0;
+
+    for &d in src {
+        if d < b'0' || d > b'9' {
+            return Err(ParseU64Error);
+        }
+
+        ret *= 10;
+        ret += (d - b'0') as u64;
+    }
+
+    Ok(ret)
+}
+
+// ===== impl PushPromise =====
+
+#[derive(Debug)]
+pub enum PushPromiseHeaderError {
+    InvalidContentLength(Result<u64, ParseU64Error>),
+    NotSafeAndCacheable,
+}
+
+impl PushPromise {
+    pub fn new(
+        stream_id: StreamId,
+        promised_id: StreamId,
+        pseudo: Pseudo,
+        fields: HeaderMap,
+    ) -> Self {
+        PushPromise {
+            flags: PushPromiseFlag::default(),
+            header_block: HeaderBlock {
+                fields,
+                is_over_size: false,
+                pseudo,
+            },
+            promised_id,
+            stream_id,
+        }
+    }
+
+    pub fn validate_request(req: &Request<()>) -> Result<(), PushPromiseHeaderError> {
+        use PushPromiseHeaderError::*;
+        // The spec has some requirements for promised request headers
+        // [https://httpwg.org/specs/rfc7540.html#PushRequests]
+
+        // A promised request "that indicates the presence of a request body
+        // MUST reset the promised stream with a stream error"
+        if let Some(content_length) = req.headers().get(header::CONTENT_LENGTH) {
+            let parsed_length = parse_u64(content_length.as_bytes());
+            if parsed_length != Ok(0) {
+                return Err(InvalidContentLength(parsed_length));
+            }
+        }
+        // "The server MUST include a method in the :method pseudo-header field
+        // that is safe and cacheable"
+        if !Self::safe_and_cacheable(req.method()) {
+            return Err(NotSafeAndCacheable);
+        }
+
+        Ok(())
+    }
+
+    fn safe_and_cacheable(method: &Method) -> bool {
+        // Cacheable: https://httpwg.org/specs/rfc7231.html#cacheable.methods
+        // Safe: https://httpwg.org/specs/rfc7231.html#safe.methods
+        method == Method::GET || method == Method::HEAD
+    }
+
+    pub fn fields(&self) -> &HeaderMap {
+        &self.header_block.fields
+    }
+
+    #[cfg(feature = "unstable")]
+    pub fn into_fields(self) -> HeaderMap {
+        self.header_block.fields
+    }
+
+    /// Loads the push promise frame but doesn't actually do HPACK decoding.
+    ///
+    /// HPACK decoding is done in the `load_hpack` step.
+    pub fn load(head: Head, mut src: BytesMut) -> Result<(Self, BytesMut), Error> {
+        let flags = PushPromiseFlag(head.flag());
+        let mut pad = 0;
+
+        if head.stream_id().is_zero() {
+            return Err(Error::InvalidStreamId);
+        }
+
+        // Read the padding length
+        if flags.is_padded() {
+            if src.is_empty() {
+                return Err(Error::MalformedMessage);
+            }
+
+            // TODO: Ensure payload is sized correctly
+            pad = src[0] as usize;
+
+            // Drop the padding
+            let _ = src.split_to(1);
+        }
+
+        if src.len() < 5 {
+            return Err(Error::MalformedMessage);
+        }
+
+        let (promised_id, _) = StreamId::parse(&src[..4]);
+        // Drop promised_id bytes
+        let _ = src.split_to(4);
+
+        if pad > 0 {
+            if pad > src.len() {
+                return Err(Error::TooMuchPadding);
+            }
+
+            let len = src.len() - pad;
+            src.truncate(len);
+        }
+
+        let frame = PushPromise {
+            flags,
+            header_block: HeaderBlock {
+                fields: HeaderMap::new(),
+                is_over_size: false,
+                pseudo: Pseudo::default(),
+            },
+            promised_id,
+            stream_id: head.stream_id(),
+        };
+        Ok((frame, src))
+    }
+
+    pub fn load_hpack(
+        &mut self,
+        src: &mut BytesMut,
+        max_header_list_size: usize,
+        decoder: &mut hpack::Decoder,
+    ) -> Result<(), Error> {
+        self.header_block.load(src, max_header_list_size, decoder)
+    }
+
+    pub fn stream_id(&self) -> StreamId {
+        self.stream_id
+    }
+
+    pub fn promised_id(&self) -> StreamId {
+        self.promised_id
+    }
+
+    pub fn is_end_headers(&self) -> bool {
+        self.flags.is_end_headers()
+    }
+
+    pub fn set_end_headers(&mut self) {
+        self.flags.set_end_headers();
+    }
+
+    pub fn is_over_size(&self) -> bool {
+        self.header_block.is_over_size
+    }
+
+    pub fn encode(
+        self,
+        encoder: &mut hpack::Encoder,
+        dst: &mut EncodeBuf<'_>,
+    ) -> Option<Continuation> {
+        // At this point, the `is_end_headers` flag should always be set
+        debug_assert!(self.flags.is_end_headers());
+
+        let head = self.head();
+        let promised_id = self.promised_id;
+
+        self.header_block
+            .into_encoding(encoder)
+            .encode(&head, dst, |dst| {
+                dst.put_u32(promised_id.into());
+            })
+    }
+
+    fn head(&self) -> Head {
+        Head::new(Kind::PushPromise, self.flags.into(), self.stream_id)
+    }
+
+    /// Consume `self`, returning the parts of the frame
+    pub fn into_parts(self) -> (Pseudo, HeaderMap) {
+        (self.header_block.pseudo, self.header_block.fields)
+    }
+}
+
+impl<T> From<PushPromise> for Frame<T> {
+    fn from(src: PushPromise) -> Self {
+        Frame::PushPromise(src)
+    }
+}
+
+impl fmt::Debug for PushPromise {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("PushPromise")
+            .field("stream_id", &self.stream_id)
+            .field("promised_id", &self.promised_id)
+            .field("flags", &self.flags)
+            // `fields` and `pseudo` purposefully not included
+            .finish()
+    }
+}
+
+// ===== impl Continuation =====
+
+impl Continuation {
+    fn head(&self) -> Head {
+        Head::new(Kind::Continuation, END_HEADERS, self.stream_id)
+    }
+
+    pub fn encode(self, dst: &mut EncodeBuf<'_>) -> Option<Continuation> {
+        // Get the CONTINUATION frame head
+        let head = self.head();
+
+        self.header_block.encode(&head, dst, |_| {})
+    }
+}
+
+// ===== impl Pseudo =====
+
+impl Pseudo {
+    pub fn request(method: Method, uri: Uri, protocol: Option<Protocol>) -> Self {
+        let parts = uri::Parts::from(uri);
+
+        let mut path = parts
+            .path_and_query
+            .map(|v| BytesStr::from(v.as_str()))
+            .unwrap_or(BytesStr::from_static(""));
+
+        match method {
+            Method::OPTIONS | Method::CONNECT => {}
+            _ if path.is_empty() => {
+                path = BytesStr::from_static("/");
+            }
+            _ => {}
+        }
+
+        let mut pseudo = Pseudo {
+            method: Some(method),
+            scheme: None,
+            authority: None,
+            path: Some(path).filter(|p| !p.is_empty()),
+            protocol,
+            status: None,
+        };
+
+        // If the URI includes a scheme component, add it to the pseudo headers
+        //
+        // TODO: Scheme must be set...
+        if let Some(scheme) = parts.scheme {
+            pseudo.set_scheme(scheme);
+        }
+
+        // If the URI includes an authority component, add it to the pseudo
+        // headers
+        if let Some(authority) = parts.authority {
+            pseudo.set_authority(BytesStr::from(authority.as_str()));
+        }
+
+        pseudo
+    }
+
+    pub fn response(status: StatusCode) -> Self {
+        Pseudo {
+            method: None,
+            scheme: None,
+            authority: None,
+            path: None,
+            protocol: None,
+            status: Some(status),
+        }
+    }
+
+    #[cfg(feature = "unstable")]
+    pub fn set_status(&mut self, value: StatusCode) {
+        self.status = Some(value);
+    }
+
+    pub fn set_scheme(&mut self, scheme: uri::Scheme) {
+        let bytes_str = match scheme.as_str() {
+            "http" => BytesStr::from_static("http"),
+            "https" => BytesStr::from_static("https"),
+            s => BytesStr::from(s),
+        };
+        self.scheme = Some(bytes_str);
+    }
+
+    #[cfg(feature = "unstable")]
+    pub fn set_protocol(&mut self, protocol: Protocol) {
+        self.protocol = Some(protocol);
+    }
+
+    pub fn set_authority(&mut self, authority: BytesStr) {
+        self.authority = Some(authority);
+    }
+
+    /// Whether it has status 1xx
+    pub(crate) fn is_informational(&self) -> bool {
+        self.status
+            .map_or(false, |status| status.is_informational())
+    }
+}
+
+// ===== impl EncodingHeaderBlock =====
+
+impl EncodingHeaderBlock {
+    fn encode<F>(mut self, head: &Head, dst: &mut EncodeBuf<'_>, f: F) -> Option<Continuation>
+    where
+        F: FnOnce(&mut EncodeBuf<'_>),
+    {
+        let head_pos = dst.get_ref().len();
+
+        // At this point, we don't know how big the h2 frame will be.
+        // So, we write the head with length 0, then write the body, and
+        // finally write the length once we know the size.
+        head.encode(0, dst);
+
+        let payload_pos = dst.get_ref().len();
+
+        f(dst);
+
+        // Now, encode the header payload
+        let continuation = if self.hpack.len() > dst.remaining_mut() {
+            dst.put_slice(&self.hpack.split_to(dst.remaining_mut()));
+
+            Some(Continuation {
+                stream_id: head.stream_id(),
+                header_block: self,
+            })
+        } else {
+            dst.put_slice(&self.hpack);
+
+            None
+        };
+
+        // Compute the header block length
+        let payload_len = (dst.get_ref().len() - payload_pos) as u64;
+
+        // Write the frame length
+        let payload_len_be = payload_len.to_be_bytes();
+        assert!(payload_len_be[0..5].iter().all(|b| *b == 0));
+        (dst.get_mut()[head_pos..head_pos + 3]).copy_from_slice(&payload_len_be[5..]);
+
+        if continuation.is_some() {
+            // There will be continuation frames, so the `is_end_headers` flag
+            // must be unset
+            debug_assert!(dst.get_ref()[head_pos + 4] & END_HEADERS == END_HEADERS);
+
+            dst.get_mut()[head_pos + 4] -= END_HEADERS;
+        }
+
+        continuation
+    }
+}
+
+// ===== impl Iter =====
+
+impl Iterator for Iter {
+    type Item = hpack::Header<Option<HeaderName>>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        use crate::hpack::Header::*;
+
+        if let Some(ref mut pseudo) = self.pseudo {
+            if let Some(method) = pseudo.method.take() {
+                return Some(Method(method));
+            }
+
+            if let Some(scheme) = pseudo.scheme.take() {
+                return Some(Scheme(scheme));
+            }
+
+            if let Some(authority) = pseudo.authority.take() {
+                return Some(Authority(authority));
+            }
+
+            if let Some(path) = pseudo.path.take() {
+                return Some(Path(path));
+            }
+
+            if let Some(protocol) = pseudo.protocol.take() {
+                return Some(Protocol(protocol));
+            }
+
+            if let Some(status) = pseudo.status.take() {
+                return Some(Status(status));
+            }
+        }
+
+        self.pseudo = None;
+
+        self.fields
+            .next()
+            .map(|(name, value)| Field { name, value })
+    }
+}
+
+// ===== impl HeadersFlag =====
+
+impl HeadersFlag {
+    pub fn empty() -> HeadersFlag {
+        HeadersFlag(0)
+    }
+
+    pub fn load(bits: u8) -> HeadersFlag {
+        HeadersFlag(bits & ALL)
+    }
+
+    pub fn is_end_stream(&self) -> bool {
+        self.0 & END_STREAM == END_STREAM
+    }
+
+    pub fn set_end_stream(&mut self) {
+        self.0 |= END_STREAM;
+    }
+
+    pub fn is_end_headers(&self) -> bool {
+        self.0 & END_HEADERS == END_HEADERS
+    }
+
+    pub fn set_end_headers(&mut self) {
+        self.0 |= END_HEADERS;
+    }
+
+    pub fn is_padded(&self) -> bool {
+        self.0 & PADDED == PADDED
+    }
+
+    pub fn is_priority(&self) -> bool {
+        self.0 & PRIORITY == PRIORITY
+    }
+}
+
+impl Default for HeadersFlag {
+    /// Returns a `HeadersFlag` value with `END_HEADERS` set.
+    fn default() -> Self {
+        HeadersFlag(END_HEADERS)
+    }
+}
+
+impl From<HeadersFlag> for u8 {
+    fn from(src: HeadersFlag) -> u8 {
+        src.0
+    }
+}
+
+impl fmt::Debug for HeadersFlag {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        util::debug_flags(fmt, self.0)
+            .flag_if(self.is_end_headers(), "END_HEADERS")
+            .flag_if(self.is_end_stream(), "END_STREAM")
+            .flag_if(self.is_padded(), "PADDED")
+            .flag_if(self.is_priority(), "PRIORITY")
+            .finish()
+    }
+}
+
+// ===== impl PushPromiseFlag =====
+
+impl PushPromiseFlag {
+    pub fn empty() -> PushPromiseFlag {
+        PushPromiseFlag(0)
+    }
+
+    pub fn load(bits: u8) -> PushPromiseFlag {
+        PushPromiseFlag(bits & ALL)
+    }
+
+    pub fn is_end_headers(&self) -> bool {
+        self.0 & END_HEADERS == END_HEADERS
+    }
+
+    pub fn set_end_headers(&mut self) {
+        self.0 |= END_HEADERS;
+    }
+
+    pub fn is_padded(&self) -> bool {
+        self.0 & PADDED == PADDED
+    }
+}
+
+impl Default for PushPromiseFlag {
+    /// Returns a `PushPromiseFlag` value with `END_HEADERS` set.
+    fn default() -> Self {
+        PushPromiseFlag(END_HEADERS)
+    }
+}
+
+impl From<PushPromiseFlag> for u8 {
+    fn from(src: PushPromiseFlag) -> u8 {
+        src.0
+    }
+}
+
+impl fmt::Debug for PushPromiseFlag {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        util::debug_flags(fmt, self.0)
+            .flag_if(self.is_end_headers(), "END_HEADERS")
+            .flag_if(self.is_padded(), "PADDED")
+            .finish()
+    }
+}
+
+// ===== HeaderBlock =====
+
+impl HeaderBlock {
+    fn load(
+        &mut self,
+        src: &mut BytesMut,
+        max_header_list_size: usize,
+        decoder: &mut hpack::Decoder,
+    ) -> Result<(), Error> {
+        let mut reg = !self.fields.is_empty();
+        let mut malformed = false;
+        let mut headers_size = self.calculate_header_list_size();
+
+        macro_rules! set_pseudo {
+            ($field:ident, $val:expr) => {{
+                if reg {
+                    tracing::trace!("load_hpack; header malformed -- pseudo not at head of block");
+                    malformed = true;
+                } else if self.pseudo.$field.is_some() {
+                    tracing::trace!("load_hpack; header malformed -- repeated pseudo");
+                    malformed = true;
+                } else {
+                    let __val = $val;
+                    headers_size +=
+                        decoded_header_size(stringify!($field).len() + 1, __val.as_str().len());
+                    if headers_size < max_header_list_size {
+                        self.pseudo.$field = Some(__val);
+                    } else if !self.is_over_size {
+                        tracing::trace!("load_hpack; header list size over max");
+                        self.is_over_size = true;
+                    }
+                }
+            }};
+        }
+
+        let mut cursor = Cursor::new(src);
+
+        // If the header frame is malformed, we still have to continue decoding
+        // the headers. A malformed header frame is a stream level error, but
+        // the hpack state is connection level. In order to maintain correct
+        // state for other streams, the hpack decoding process must complete.
+        let res = decoder.decode(&mut cursor, |header| {
+            use crate::hpack::Header::*;
+
+            match header {
+                Field { name, value } => {
+                    // Connection level header fields are not supported and must
+                    // result in a protocol error.
+
+                    if name == header::CONNECTION
+                        || name == header::TRANSFER_ENCODING
+                        || name == header::UPGRADE
+                        || name == "keep-alive"
+                        || name == "proxy-connection"
+                    {
+                        tracing::trace!("load_hpack; connection level header");
+                        malformed = true;
+                    } else if name == header::TE && value != "trailers" {
+                        tracing::trace!(
+                            "load_hpack; TE header not set to trailers; val={:?}",
+                            value
+                        );
+                        malformed = true;
+                    } else {
+                        reg = true;
+
+                        headers_size += decoded_header_size(name.as_str().len(), value.len());
+                        if headers_size < max_header_list_size {
+                            self.fields.append(name, value);
+                        } else if !self.is_over_size {
+                            tracing::trace!("load_hpack; header list size over max");
+                            self.is_over_size = true;
+                        }
+                    }
+                }
+                Authority(v) => set_pseudo!(authority, v),
+                Method(v) => set_pseudo!(method, v),
+                Scheme(v) => set_pseudo!(scheme, v),
+                Path(v) => set_pseudo!(path, v),
+                Protocol(v) => set_pseudo!(protocol, v),
+                Status(v) => set_pseudo!(status, v),
+            }
+        });
+
+        if let Err(e) = res {
+            tracing::trace!("hpack decoding error; err={:?}", e);
+            return Err(e.into());
+        }
+
+        if malformed {
+            tracing::trace!("malformed message");
+            return Err(Error::MalformedMessage);
+        }
+
+        Ok(())
+    }
+
+    fn into_encoding(self, encoder: &mut hpack::Encoder) -> EncodingHeaderBlock {
+        let mut hpack = BytesMut::new();
+        let headers = Iter {
+            pseudo: Some(self.pseudo),
+            fields: self.fields.into_iter(),
+        };
+
+        encoder.encode(headers, &mut hpack);
+
+        EncodingHeaderBlock {
+            hpack: hpack.freeze(),
+        }
+    }
+
+    /// Calculates the size of the currently decoded header list.
+    ///
+    /// According to http://httpwg.org/specs/rfc7540.html#SETTINGS_MAX_HEADER_LIST_SIZE
+    ///
+    /// > The value is based on the uncompressed size of header fields,
+    /// > including the length of the name and value in octets plus an
+    /// > overhead of 32 octets for each header field.
+    fn calculate_header_list_size(&self) -> usize {
+        macro_rules! pseudo_size {
+            ($name:ident) => {{
+                self.pseudo
+                    .$name
+                    .as_ref()
+                    .map(|m| decoded_header_size(stringify!($name).len() + 1, m.as_str().len()))
+                    .unwrap_or(0)
+            }};
+        }
+
+        pseudo_size!(method)
+            + pseudo_size!(scheme)
+            + pseudo_size!(status)
+            + pseudo_size!(authority)
+            + pseudo_size!(path)
+            + self
+                .fields
+                .iter()
+                .map(|(name, value)| decoded_header_size(name.as_str().len(), value.len()))
+                .sum::<usize>()
+    }
+}
+
+fn decoded_header_size(name: usize, value: usize) -> usize {
+    name + value + 32
+}
+
+#[cfg(test)]
+mod test {
+    use std::iter::FromIterator;
+
+    use http::HeaderValue;
+
+    use super::*;
+    use crate::frame;
+    use crate::hpack::{huffman, Encoder};
+
+    #[test]
+    fn test_nameless_header_at_resume() {
+        let mut encoder = Encoder::default();
+        let mut dst = BytesMut::new();
+
+        let headers = Headers::new(
+            StreamId::ZERO,
+            Default::default(),
+            HeaderMap::from_iter(vec![
+                (
+                    HeaderName::from_static("hello"),
+                    HeaderValue::from_static("world"),
+                ),
+                (
+                    HeaderName::from_static("hello"),
+                    HeaderValue::from_static("zomg"),
+                ),
+                (
+                    HeaderName::from_static("hello"),
+                    HeaderValue::from_static("sup"),
+                ),
+            ]),
+        );
+
+        let continuation = headers
+            .encode(&mut encoder, &mut (&mut dst).limit(frame::HEADER_LEN + 8))
+            .unwrap();
+
+        assert_eq!(17, dst.len());
+        assert_eq!([0, 0, 8, 1, 0, 0, 0, 0, 0], &dst[0..9]);
+        assert_eq!(&[0x40, 0x80 | 4], &dst[9..11]);
+        assert_eq!("hello", huff_decode(&dst[11..15]));
+        assert_eq!(0x80 | 4, dst[15]);
+
+        let mut world = dst[16..17].to_owned();
+
+        dst.clear();
+
+        assert!(continuation
+            .encode(&mut (&mut dst).limit(frame::HEADER_LEN + 16))
+            .is_none());
+
+        world.extend_from_slice(&dst[9..12]);
+        assert_eq!("world", huff_decode(&world));
+
+        assert_eq!(24, dst.len());
+        assert_eq!([0, 0, 15, 9, 4, 0, 0, 0, 0], &dst[0..9]);
+
+        // // Next is not indexed
+        assert_eq!(&[15, 47, 0x80 | 3], &dst[12..15]);
+        assert_eq!("zomg", huff_decode(&dst[15..18]));
+        assert_eq!(&[15, 47, 0x80 | 3], &dst[18..21]);
+        assert_eq!("sup", huff_decode(&dst[21..]));
+    }
+
+    fn huff_decode(src: &[u8]) -> BytesMut {
+        let mut buf = BytesMut::new();
+        huffman::decode(src, &mut buf).unwrap()
+    }
+}
diff --git a/third_party/rust/h2/src/frame/mod.rs b/third_party/rust/h2/src/frame/mod.rs
new file mode 100644
index 0000000000..0e8e7035c3
--- /dev/null
+++ b/third_party/rust/h2/src/frame/mod.rs
@@ -0,0 +1,171 @@
+use crate::hpack;
+
+use bytes::Bytes;
+
+use std::fmt;
+
+/// A helper macro that unpacks a sequence of 4 bytes found in the buffer with
+/// the given identifier, starting at the given offset, into the given integer
+/// type. Obviously, the integer type should be able to support at least 4
+/// bytes.
+///
+/// # Examples
+///
+/// ```ignore
+/// # // We ignore this doctest because the macro is not exported.
+/// let buf: [u8; 4] = [0, 0, 0, 1];
+/// assert_eq!(1u32, unpack_octets_4!(buf, 0, u32));
+/// ```
+macro_rules! unpack_octets_4 {
+    // TODO: Get rid of this macro
+    ($buf:expr, $offset:expr, $tip:ty) => {
+        (($buf[$offset + 0] as $tip) << 24)
+            | (($buf[$offset + 1] as $tip) << 16)
+            | (($buf[$offset + 2] as $tip) << 8)
+            | (($buf[$offset + 3] as $tip) << 0)
+    };
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn test_unpack_octets_4() {
+        let buf: [u8; 4] = [0, 0, 0, 1];
+        assert_eq!(1u32, unpack_octets_4!(buf, 0, u32));
+    }
+}
+
+mod data;
+mod go_away;
+mod head;
+mod headers;
+mod ping;
+mod priority;
+mod reason;
+mod reset;
+mod settings;
+mod stream_id;
+mod util;
+mod window_update;
+
+pub use self::data::Data;
+pub use self::go_away::GoAway;
+pub use self::head::{Head, Kind};
+pub use self::headers::{
+    parse_u64, Continuation, Headers, Pseudo, PushPromise, PushPromiseHeaderError,
+};
+pub use self::ping::Ping;
+pub use self::priority::{Priority, StreamDependency};
+pub use self::reason::Reason;
+pub use self::reset::Reset;
+pub use self::settings::Settings;
+pub use self::stream_id::{StreamId, StreamIdOverflow};
+pub use self::window_update::WindowUpdate;
+
+#[cfg(feature = "unstable")]
+pub use crate::hpack::BytesStr;
+
+// Re-export some constants
+
+pub use self::settings::{
+    DEFAULT_INITIAL_WINDOW_SIZE, DEFAULT_MAX_FRAME_SIZE, DEFAULT_SETTINGS_HEADER_TABLE_SIZE,
+    MAX_MAX_FRAME_SIZE,
+};
+
+pub type FrameSize = u32;
+
+pub const HEADER_LEN: usize = 9;
+
+#[derive(Eq, PartialEq)]
+pub enum Frame<T = Bytes> {
+    Data(Data<T>),
+    Headers(Headers),
+    Priority(Priority),
+    PushPromise(PushPromise),
+    Settings(Settings),
+    Ping(Ping),
+    GoAway(GoAway),
+    WindowUpdate(WindowUpdate),
+    Reset(Reset),
+}
+
+impl<T> Frame<T> {
+    pub fn map<F, U>(self, f: F) -> Frame<U>
+    where
+        F: FnOnce(T) -> U,
+    {
+        use self::Frame::*;
+
+        match self {
+            Data(frame) => frame.map(f).into(),
+            Headers(frame) => frame.into(),
+            Priority(frame) => frame.into(),
+            PushPromise(frame) => frame.into(),
+            Settings(frame) => frame.into(),
+            Ping(frame) => frame.into(),
+            GoAway(frame) => frame.into(),
+            WindowUpdate(frame) => frame.into(),
+            Reset(frame) => frame.into(),
+        }
+    }
+}
+
+impl<T> fmt::Debug for Frame<T> {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        use self::Frame::*;
+
+        match *self {
+            Data(ref frame) => fmt::Debug::fmt(frame, fmt),
+            Headers(ref frame) => fmt::Debug::fmt(frame, fmt),
+            Priority(ref frame) => fmt::Debug::fmt(frame, fmt),
+            PushPromise(ref frame) => fmt::Debug::fmt(frame, fmt),
+            Settings(ref frame) => fmt::Debug::fmt(frame, fmt),
+            Ping(ref frame) => fmt::Debug::fmt(frame, fmt),
+            GoAway(ref frame) => fmt::Debug::fmt(frame, fmt),
+            WindowUpdate(ref frame) => fmt::Debug::fmt(frame, fmt),
+            Reset(ref frame) => fmt::Debug::fmt(frame, fmt),
+        }
+    }
+}
+
+/// Errors that can occur during parsing an HTTP/2 frame.
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum Error {
+    /// A length value other than 8 was set on a PING message.
+    BadFrameSize,
+
+    /// The padding length was larger than the frame-header-specified
+    /// length of the payload.
+    TooMuchPadding,
+
+    /// An invalid setting value was provided
+    InvalidSettingValue,
+
+    /// An invalid window update value
+    InvalidWindowUpdateValue,
+
+    /// The payload length specified by the frame header was not the
+    /// value necessary for the specific frame type.
+    InvalidPayloadLength,
+
+    /// Received a payload with an ACK settings frame
+    InvalidPayloadAckSettings,
+
+    /// An invalid stream identifier was provided.
+    ///
+    /// This is returned if a SETTINGS or PING frame is received with a stream
+    /// identifier other than zero.
+    InvalidStreamId,
+
+    /// A request or response is malformed.
+    MalformedMessage,
+
+    /// An invalid stream dependency ID was provided
+    ///
+    /// This is returned if a HEADERS or PRIORITY frame is received with an
+    /// invalid stream identifier.
+    InvalidDependencyId,
+
+    /// Failed to perform HPACK decoding
+    Hpack(hpack::DecoderError),
+}
diff --git a/third_party/rust/h2/src/frame/ping.rs b/third_party/rust/h2/src/frame/ping.rs
new file mode 100644
index 0000000000..241d06ea17
--- /dev/null
+++ b/third_party/rust/h2/src/frame/ping.rs
@@ -0,0 +1,102 @@
+use crate::frame::{Error, Frame, Head, Kind, StreamId};
+use bytes::BufMut;
+
+const ACK_FLAG: u8 = 0x1;
+
+pub type Payload = [u8; 8];
+
+#[derive(Debug, Eq, PartialEq)]
+pub struct Ping {
+    ack: bool,
+    payload: Payload,
+}
+
+// This was just 8 randomly generated bytes. We use something besides just
+// zeroes to distinguish this specific PING from any other.
+const SHUTDOWN_PAYLOAD: Payload = [0x0b, 0x7b, 0xa2, 0xf0, 0x8b, 0x9b, 0xfe, 0x54];
+const USER_PAYLOAD: Payload = [0x3b, 0x7c, 0xdb, 0x7a, 0x0b, 0x87, 0x16, 0xb4];
+
+impl Ping {
+    #[cfg(feature = "unstable")]
+    pub const SHUTDOWN: Payload = SHUTDOWN_PAYLOAD;
+
+    #[cfg(not(feature = "unstable"))]
+    pub(crate) const SHUTDOWN: Payload = SHUTDOWN_PAYLOAD;
+
+    #[cfg(feature = "unstable")]
+    pub const USER: Payload = USER_PAYLOAD;
+
+    #[cfg(not(feature = "unstable"))]
+    pub(crate) const USER: Payload = USER_PAYLOAD;
+
+    pub fn new(payload: Payload) -> Ping {
+        Ping {
+            ack: false,
+            payload,
+        }
+    }
+
+    pub fn pong(payload: Payload) -> Ping {
+        Ping { ack: true, payload }
+    }
+
+    pub fn is_ack(&self) -> bool {
+        self.ack
+    }
+
+    pub fn payload(&self) -> &Payload {
+        &self.payload
+    }
+
+    pub fn into_payload(self) -> Payload {
+        self.payload
+    }
+
+    /// Builds a `Ping` frame from a raw frame.
+    pub fn load(head: Head, bytes: &[u8]) -> Result<Ping, Error> {
+        debug_assert_eq!(head.kind(), crate::frame::Kind::Ping);
+
+        // PING frames are not associated with any individual stream. If a PING
+        // frame is received with a stream identifier field value other than
+        // 0x0, the recipient MUST respond with a connection error
+        // (Section 5.4.1) of type PROTOCOL_ERROR.
+        if !head.stream_id().is_zero() {
+            return Err(Error::InvalidStreamId);
+        }
+
+        // In addition to the frame header, PING frames MUST contain 8 octets of opaque
+        // data in the payload.
+        if bytes.len() != 8 {
+            return Err(Error::BadFrameSize);
+        }
+
+        let mut payload = [0; 8];
+        payload.copy_from_slice(bytes);
+
+        // The PING frame defines the following flags:
+        //
+        // ACK (0x1): When set, bit 0 indicates that this PING frame is a PING
+        //    response. An endpoint MUST set this flag in PING responses. An
+        //    endpoint MUST NOT respond to PING frames containing this flag.
+        let ack = head.flag() & ACK_FLAG != 0;
+
+        Ok(Ping { ack, payload })
+    }
+
+    pub fn encode<B: BufMut>(&self, dst: &mut B) {
+        let sz = self.payload.len();
+        tracing::trace!("encoding PING; ack={} len={}", self.ack, sz);
+
+        let flags = if self.ack { ACK_FLAG } else { 0 };
+        let head = Head::new(Kind::Ping, flags, StreamId::zero());
+
+        head.encode(sz, dst);
+        dst.put_slice(&self.payload);
+    }
+}
+
+impl<T> From<Ping> for Frame<T> {
+    fn from(src: Ping) -> Frame<T> {
+        Frame::Ping(src)
+    }
+}
diff --git a/third_party/rust/h2/src/frame/priority.rs b/third_party/rust/h2/src/frame/priority.rs
new file mode 100644
index 0000000000..d7d47dbb01
--- /dev/null
+++ b/third_party/rust/h2/src/frame/priority.rs
@@ -0,0 +1,72 @@
+use crate::frame::*;
+
+#[derive(Debug, Eq, PartialEq)]
+pub struct Priority {
+    stream_id: StreamId,
+    dependency: StreamDependency,
+}
+
+#[derive(Debug, Eq, PartialEq)]
+pub struct StreamDependency {
+    /// The ID of the stream dependency target
+    dependency_id: StreamId,
+
+    /// The weight for the stream. The value exposed (and set) here is always in
+    /// the range [0, 255], instead of [1, 256] (as defined in section 5.3.2.)
+    /// so that the value fits into a `u8`.
+    weight: u8,
+
+    /// True if the stream dependency is exclusive.
+    is_exclusive: bool,
+}
+
+impl Priority {
+    pub fn load(head: Head, payload: &[u8]) -> Result<Self, Error> {
+        let dependency = StreamDependency::load(payload)?;
+
+        if dependency.dependency_id() == head.stream_id() {
+            return Err(Error::InvalidDependencyId);
+        }
+
+        Ok(Priority {
+            stream_id: head.stream_id(),
+            dependency,
+        })
+    }
+}
+
+impl<B> From<Priority> for Frame<B> {
+    fn from(src: Priority) -> Self {
+        Frame::Priority(src)
+    }
+}
+
+// ===== impl StreamDependency =====
+
+impl StreamDependency {
+    pub fn new(dependency_id: StreamId, weight: u8, is_exclusive: bool) -> Self {
+        StreamDependency {
+            dependency_id,
+            weight,
+            is_exclusive,
+        }
+    }
+
+    pub fn load(src: &[u8]) -> Result<Self, Error> {
+        if src.len() != 5 {
+            return Err(Error::InvalidPayloadLength);
+        }
+
+        // Parse the stream ID and exclusive flag
+        let (dependency_id, is_exclusive) = StreamId::parse(&src[..4]);
+
+        // Read the weight
+        let weight = src[4];
+
+        Ok(StreamDependency::new(dependency_id, weight, is_exclusive))
+    }
+
+    pub fn dependency_id(&self) -> StreamId {
+        self.dependency_id
+    }
+}
diff --git a/third_party/rust/h2/src/frame/reason.rs b/third_party/rust/h2/src/frame/reason.rs
new file mode 100644
index 0000000000..ff5e2012f8
--- /dev/null
+++ b/third_party/rust/h2/src/frame/reason.rs
@@ -0,0 +1,134 @@
+use std::fmt;
+
+/// HTTP/2 error codes.
+///
+/// Error codes are used in `RST_STREAM` and `GOAWAY` frames to convey the
+/// reasons for the stream or connection error. For example,
+/// [`SendStream::send_reset`] takes a `Reason` argument. Also, the `Error` type
+/// may contain a `Reason`.
+///
+/// Error codes share a common code space. Some error codes apply only to
+/// streams, others apply only to connections, and others may apply to either.
+/// See [RFC 7540] for more information.
+///
+/// See [Error Codes in the spec][spec].
+///
+/// [spec]: http://httpwg.org/specs/rfc7540.html#ErrorCodes
+/// [`SendStream::send_reset`]: struct.SendStream.html#method.send_reset
+#[derive(PartialEq, Eq, Clone, Copy)]
+pub struct Reason(u32);
+
+impl Reason {
+    /// The associated condition is not a result of an error.
+    ///
+    /// For example, a GOAWAY might include this code to indicate graceful
+    /// shutdown of a connection.
+    pub const NO_ERROR: Reason = Reason(0);
+    /// The endpoint detected an unspecific protocol error.
+    ///
+    /// This error is for use when a more specific error code is not available.
+    pub const PROTOCOL_ERROR: Reason = Reason(1);
+    /// The endpoint encountered an unexpected internal error.
+    pub const INTERNAL_ERROR: Reason = Reason(2);
+    /// The endpoint detected that its peer violated the flow-control protocol.
+    pub const FLOW_CONTROL_ERROR: Reason = Reason(3);
+    /// The endpoint sent a SETTINGS frame but did not receive a response in
+    /// a timely manner.
+    pub const SETTINGS_TIMEOUT: Reason = Reason(4);
+    /// The endpoint received a frame after a stream was half-closed.
+    pub const STREAM_CLOSED: Reason = Reason(5);
+    /// The endpoint received a frame with an invalid size.
+    pub const FRAME_SIZE_ERROR: Reason = Reason(6);
+    /// The endpoint refused the stream prior to performing any application
+    /// processing.
+    pub const REFUSED_STREAM: Reason = Reason(7);
+    /// Used by the endpoint to indicate that the stream is no longer needed.
+    pub const CANCEL: Reason = Reason(8);
+    /// The endpoint is unable to maintain the header compression context for
+    /// the connection.
+    pub const COMPRESSION_ERROR: Reason = Reason(9);
+    /// The connection established in response to a CONNECT request was reset
+    /// or abnormally closed.
+    pub const CONNECT_ERROR: Reason = Reason(10);
+    /// The endpoint detected that its peer is exhibiting a behavior that might
+    /// be generating excessive load.
+    pub const ENHANCE_YOUR_CALM: Reason = Reason(11);
+    /// The underlying transport has properties that do not meet minimum
+    /// security requirements.
+    pub const INADEQUATE_SECURITY: Reason = Reason(12);
+    /// The endpoint requires that HTTP/1.1 be used instead of HTTP/2.
+    pub const HTTP_1_1_REQUIRED: Reason = Reason(13);
+
+    /// Get a string description of the error code.
+    pub fn description(&self) -> &str {
+        match self.0 {
+            0 => "not a result of an error",
+            1 => "unspecific protocol error detected",
+            2 => "unexpected internal error encountered",
+            3 => "flow-control protocol violated",
+            4 => "settings ACK not received in timely manner",
+            5 => "received frame when stream half-closed",
+            6 => "frame with invalid size",
+            7 => "refused stream before processing any application logic",
+            8 => "stream no longer needed",
+            9 => "unable to maintain the header compression context",
+            10 => {
+                "connection established in response to a CONNECT request was reset or abnormally \
+                 closed"
+            }
+            11 => "detected excessive load generating behavior",
+            12 => "security properties do not meet minimum requirements",
+            13 => "endpoint requires HTTP/1.1",
+            _ => "unknown reason",
+        }
+    }
+}
+
+impl From<u32> for Reason {
+    fn from(src: u32) -> Reason {
+        Reason(src)
+    }
+}
+
+impl From<Reason> for u32 {
+    fn from(src: Reason) -> u32 {
+        src.0
+    }
+}
+
+impl fmt::Debug for Reason {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let name = match self.0 {
+            0 => "NO_ERROR",
+            1 => "PROTOCOL_ERROR",
+            2 => "INTERNAL_ERROR",
+            3 => "FLOW_CONTROL_ERROR",
+            4 => "SETTINGS_TIMEOUT",
+            5 => "STREAM_CLOSED",
+            6 => "FRAME_SIZE_ERROR",
+            7 => "REFUSED_STREAM",
+            8 => "CANCEL",
+            9 => "COMPRESSION_ERROR",
+            10 => "CONNECT_ERROR",
+            11 => "ENHANCE_YOUR_CALM",
+            12 => "INADEQUATE_SECURITY",
+            13 => "HTTP_1_1_REQUIRED",
+            other => return f.debug_tuple("Reason").field(&Hex(other)).finish(),
+        };
+        f.write_str(name)
+    }
+}
+
+struct Hex(u32);
+
+impl fmt::Debug for Hex {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::LowerHex::fmt(&self.0, f)
+    }
+}
+
+impl fmt::Display for Reason {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt, "{}", self.description())
+    }
+}
diff --git a/third_party/rust/h2/src/frame/reset.rs b/third_party/rust/h2/src/frame/reset.rs
new file mode 100644
index 0000000000..39f6ac2022
--- /dev/null
+++ b/third_party/rust/h2/src/frame/reset.rs
@@ -0,0 +1,56 @@
+use crate::frame::{self, Error, Head, Kind, Reason, StreamId};
+
+use bytes::BufMut;
+
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub struct Reset {
+    stream_id: StreamId,
+    error_code: Reason,
+}
+
+impl Reset {
+    pub fn new(stream_id: StreamId, error: Reason) -> Reset {
+        Reset {
+            stream_id,
+            error_code: error,
+        }
+    }
+
+    pub fn stream_id(&self) -> StreamId {
+        self.stream_id
+    }
+
+    pub fn reason(&self) -> Reason {
+        self.error_code
+    }
+
+    pub fn load(head: Head, payload: &[u8]) -> Result<Reset, Error> {
+        if payload.len() != 4 {
+            return Err(Error::InvalidPayloadLength);
+        }
+
+        let error_code = unpack_octets_4!(payload, 0, u32);
+
+        Ok(Reset {
+            stream_id: head.stream_id(),
+            error_code: error_code.into(),
+        })
+    }
+
+    pub fn encode<B: BufMut>(&self, dst: &mut B) {
+        tracing::trace!(
+            "encoding RESET; id={:?} code={:?}",
+            self.stream_id,
+            self.error_code
+        );
+        let head = Head::new(Kind::Reset, 0, self.stream_id);
+        head.encode(4, dst);
+        dst.put_u32(self.error_code.into());
+    }
+}
+
+impl<B> From<Reset> for frame::Frame<B> {
+    fn from(src: Reset) -> Self {
+        frame::Frame::Reset(src)
+    }
+}
diff --git a/third_party/rust/h2/src/frame/settings.rs b/third_party/rust/h2/src/frame/settings.rs
new file mode 100644
index 0000000000..484498a9d9
--- /dev/null
+++ b/third_party/rust/h2/src/frame/settings.rs
@@ -0,0 +1,389 @@
+use std::fmt;
+
+use crate::frame::{util, Error, Frame, FrameSize, Head, Kind, StreamId};
+use bytes::{BufMut, BytesMut};
+
+#[derive(Clone, Default, Eq, PartialEq)]
+pub struct Settings {
+    flags: SettingsFlags,
+    // Fields
+    header_table_size: Option<u32>,
+    enable_push: Option<u32>,
+    max_concurrent_streams: Option<u32>,
+    initial_window_size: Option<u32>,
+    max_frame_size: Option<u32>,
+    max_header_list_size: Option<u32>,
+    enable_connect_protocol: Option<u32>,
+}
+
+/// An enum that lists all valid settings that can be sent in a SETTINGS
+/// frame.
+///
+/// Each setting has a value that is a 32 bit unsigned integer (6.5.1.).
+#[derive(Debug)]
+pub enum Setting {
+    HeaderTableSize(u32),
+    EnablePush(u32),
+    MaxConcurrentStreams(u32),
+    InitialWindowSize(u32),
+    MaxFrameSize(u32),
+    MaxHeaderListSize(u32),
+    EnableConnectProtocol(u32),
+}
+
+#[derive(Copy, Clone, Eq, PartialEq, Default)]
+pub struct SettingsFlags(u8);
+
+const ACK: u8 = 0x1;
+const ALL: u8 = ACK;
+
+/// The default value of SETTINGS_HEADER_TABLE_SIZE
+pub const DEFAULT_SETTINGS_HEADER_TABLE_SIZE: usize = 4_096;
+
+/// The default value of SETTINGS_INITIAL_WINDOW_SIZE
+pub const DEFAULT_INITIAL_WINDOW_SIZE: u32 = 65_535;
+
+/// The default value of MAX_FRAME_SIZE
+pub const DEFAULT_MAX_FRAME_SIZE: FrameSize = 16_384;
+
+/// INITIAL_WINDOW_SIZE upper bound
+pub const MAX_INITIAL_WINDOW_SIZE: usize = (1 << 31) - 1;
+
+/// MAX_FRAME_SIZE upper bound
+pub const MAX_MAX_FRAME_SIZE: FrameSize = (1 << 24) - 1;
+
+// ===== impl Settings =====
+
+impl Settings {
+    pub fn ack() -> Settings {
+        Settings {
+            flags: SettingsFlags::ack(),
+            ..Settings::default()
+        }
+    }
+
+    pub fn is_ack(&self) -> bool {
+        self.flags.is_ack()
+    }
+
+    pub fn initial_window_size(&self) -> Option<u32> {
+        self.initial_window_size
+    }
+
+    pub fn set_initial_window_size(&mut self, size: Option<u32>) {
+        self.initial_window_size = size;
+    }
+
+    pub fn max_concurrent_streams(&self) -> Option<u32> {
+        self.max_concurrent_streams
+    }
+
+    pub fn set_max_concurrent_streams(&mut self, max: Option<u32>) {
+        self.max_concurrent_streams = max;
+    }
+
+    pub fn max_frame_size(&self) -> Option<u32> {
+        self.max_frame_size
+    }
+
+    pub fn set_max_frame_size(&mut self, size: Option<u32>) {
+        if let Some(val) = size {
+            assert!(DEFAULT_MAX_FRAME_SIZE <= val && val <= MAX_MAX_FRAME_SIZE);
+        }
+        self.max_frame_size = size;
+    }
+
+    pub fn max_header_list_size(&self) -> Option<u32> {
+        self.max_header_list_size
+    }
+
+    pub fn set_max_header_list_size(&mut self, size: Option<u32>) {
+        self.max_header_list_size = size;
+    }
+
+    pub fn is_push_enabled(&self) -> Option<bool> {
+        self.enable_push.map(|val| val != 0)
+    }
+
+    pub fn set_enable_push(&mut self, enable: bool) {
+        self.enable_push = Some(enable as u32);
+    }
+
+    pub fn is_extended_connect_protocol_enabled(&self) -> Option<bool> {
+        self.enable_connect_protocol.map(|val| val != 0)
+    }
+
+    pub fn set_enable_connect_protocol(&mut self, val: Option<u32>) {
+        self.enable_connect_protocol = val;
+    }
+
+    pub fn header_table_size(&self) -> Option<u32> {
+        self.header_table_size
+    }
+
+    pub fn set_header_table_size(&mut self, size: Option<u32>) {
+        self.header_table_size = size;
+    }
+
+    pub fn load(head: Head, payload: &[u8]) -> Result<Settings, Error> {
+        use self::Setting::*;
+
+        debug_assert_eq!(head.kind(), crate::frame::Kind::Settings);
+
+        if !head.stream_id().is_zero() {
+            return Err(Error::InvalidStreamId);
+        }
+
+        // Load the flag
+        let flag = SettingsFlags::load(head.flag());
+
+        if flag.is_ack() {
+            // Ensure that the payload is empty
+            if !payload.is_empty() {
+                return Err(Error::InvalidPayloadLength);
+            }
+
+            // Return the ACK frame
+            return Ok(Settings::ack());
+        }
+
+        // Ensure the payload length is correct, each setting is 6 bytes long.
+        if payload.len() % 6 != 0 {
+            tracing::debug!("invalid settings payload length; len={:?}", payload.len());
+            return Err(Error::InvalidPayloadAckSettings);
+        }
+
+        let mut settings = Settings::default();
+        debug_assert!(!settings.flags.is_ack());
+
+        for raw in payload.chunks(6) {
+            match Setting::load(raw) {
+                Some(HeaderTableSize(val)) => {
+                    settings.header_table_size = Some(val);
+                }
+                Some(EnablePush(val)) => match val {
+                    0 | 1 => {
+                        settings.enable_push = Some(val);
+                    }
+                    _ => {
+                        return Err(Error::InvalidSettingValue);
+                    }
+                },
+                Some(MaxConcurrentStreams(val)) => {
+                    settings.max_concurrent_streams = Some(val);
+                }
+                Some(InitialWindowSize(val)) => {
+                    if val as usize > MAX_INITIAL_WINDOW_SIZE {
+                        return Err(Error::InvalidSettingValue);
+                    } else {
+                        settings.initial_window_size = Some(val);
+                    }
+                }
+                Some(MaxFrameSize(val)) => {
+                    if DEFAULT_MAX_FRAME_SIZE <= val && val <= MAX_MAX_FRAME_SIZE {
+                        settings.max_frame_size = Some(val);
+                    } else {
+                        return Err(Error::InvalidSettingValue);
+                    }
+                }
+                Some(MaxHeaderListSize(val)) => {
+                    settings.max_header_list_size = Some(val);
+                }
+                Some(EnableConnectProtocol(val)) => match val {
+                    0 | 1 => {
+                        settings.enable_connect_protocol = Some(val);
+                    }
+                    _ => {
+                        return Err(Error::InvalidSettingValue);
+                    }
+                },
+                None => {}
+            }
+        }
+
+        Ok(settings)
+    }
+
+    fn payload_len(&self) -> usize {
+        let mut len = 0;
+        self.for_each(|_| len += 6);
+        len
+    }
+
+    pub fn encode(&self, dst: &mut BytesMut) {
+        // Create & encode an appropriate frame head
+        let head = Head::new(Kind::Settings, self.flags.into(), StreamId::zero());
+        let payload_len = self.payload_len();
+
+        tracing::trace!("encoding SETTINGS; len={}", payload_len);
+
+        head.encode(payload_len, dst);
+
+        // Encode the settings
+        self.for_each(|setting| {
+            tracing::trace!("encoding setting; val={:?}", setting);
+            setting.encode(dst)
+        });
+    }
+
+    fn for_each<F: FnMut(Setting)>(&self, mut f: F) {
+        use self::Setting::*;
+
+        if let Some(v) = self.header_table_size {
+            f(HeaderTableSize(v));
+        }
+
+        if let Some(v) = self.enable_push {
+            f(EnablePush(v));
+        }
+
+        if let Some(v) = self.max_concurrent_streams {
+            f(MaxConcurrentStreams(v));
+        }
+
+        if let Some(v) = self.initial_window_size {
+            f(InitialWindowSize(v));
+        }
+
+        if let Some(v) = self.max_frame_size {
+            f(MaxFrameSize(v));
+        }
+
+        if let Some(v) = self.max_header_list_size {
+            f(MaxHeaderListSize(v));
+        }
+
+        if let Some(v) = self.enable_connect_protocol {
+            f(EnableConnectProtocol(v));
+        }
+    }
+}
+
+impl<T> From<Settings> for Frame<T> {
+    fn from(src: Settings) -> Frame<T> {
+        Frame::Settings(src)
+    }
+}
+
+impl fmt::Debug for Settings {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let mut builder = f.debug_struct("Settings");
+        builder.field("flags", &self.flags);
+
+        self.for_each(|setting| match setting {
+            Setting::EnablePush(v) => {
+                builder.field("enable_push", &v);
+            }
+            Setting::HeaderTableSize(v) => {
+                builder.field("header_table_size", &v);
+            }
+            Setting::InitialWindowSize(v) => {
+                builder.field("initial_window_size", &v);
+            }
+            Setting::MaxConcurrentStreams(v) => {
+                builder.field("max_concurrent_streams", &v);
+            }
+            Setting::MaxFrameSize(v) => {
+                builder.field("max_frame_size", &v);
+            }
+            Setting::MaxHeaderListSize(v) => {
+                builder.field("max_header_list_size", &v);
+            }
+            Setting::EnableConnectProtocol(v) => {
+                builder.field("enable_connect_protocol", &v);
+            }
+        });
+
+        builder.finish()
+    }
+}
+
+// ===== impl Setting =====
+
+impl Setting {
+    /// Creates a new `Setting` with the correct variant corresponding to the
+    /// given setting id, based on the settings IDs defined in section
+    /// 6.5.2.
+    pub fn from_id(id: u16, val: u32) -> Option<Setting> {
+        use self::Setting::*;
+
+        match id {
+            1 => Some(HeaderTableSize(val)),
+            2 => Some(EnablePush(val)),
+            3 => Some(MaxConcurrentStreams(val)),
+            4 => Some(InitialWindowSize(val)),
+            5 => Some(MaxFrameSize(val)),
+            6 => Some(MaxHeaderListSize(val)),
+            8 => Some(EnableConnectProtocol(val)),
+            _ => None,
+        }
+    }
+
+    /// Creates a new `Setting` by parsing the given buffer of 6 bytes, which
+    /// contains the raw byte representation of the setting, according to the
+    /// "SETTINGS format" defined in section 6.5.1.
+    ///
+    /// The `raw` parameter should have length at least 6 bytes, since the
+    /// length of the raw setting is exactly 6 bytes.
+    ///
+    /// # Panics
+    ///
+    /// If given a buffer shorter than 6 bytes, the function will panic.
+    fn load(raw: &[u8]) -> Option<Setting> {
+        let id: u16 = (u16::from(raw[0]) << 8) | u16::from(raw[1]);
+        let val: u32 = unpack_octets_4!(raw, 2, u32);
+
+        Setting::from_id(id, val)
+    }
+
+    fn encode(&self, dst: &mut BytesMut) {
+        use self::Setting::*;
+
+        let (kind, val) = match *self {
+            HeaderTableSize(v) => (1, v),
+            EnablePush(v) => (2, v),
+            MaxConcurrentStreams(v) => (3, v),
+            InitialWindowSize(v) => (4, v),
+            MaxFrameSize(v) => (5, v),
+            MaxHeaderListSize(v) => (6, v),
+            EnableConnectProtocol(v) => (8, v),
+        };
+
+        dst.put_u16(kind);
+        dst.put_u32(val);
+    }
+}
+
+// ===== impl SettingsFlags =====
+
+impl SettingsFlags {
+    pub fn empty() -> SettingsFlags {
+        SettingsFlags(0)
+    }
+
+    pub fn load(bits: u8) -> SettingsFlags {
+        SettingsFlags(bits & ALL)
+    }
+
+    pub fn ack() -> SettingsFlags {
+        SettingsFlags(ACK)
+    }
+
+    pub fn is_ack(&self) -> bool {
+        self.0 & ACK == ACK
+    }
+}
+
+impl From<SettingsFlags> for u8 {
+    fn from(src: SettingsFlags) -> u8 {
+        src.0
+    }
+}
+
+impl fmt::Debug for SettingsFlags {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        util::debug_flags(f, self.0)
+            .flag_if(self.is_ack(), "ACK")
+            .finish()
+    }
+}
diff --git a/third_party/rust/h2/src/frame/stream_id.rs b/third_party/rust/h2/src/frame/stream_id.rs
new file mode 100644
index 0000000000..10a14d3c82
--- /dev/null
+++ b/third_party/rust/h2/src/frame/stream_id.rs
@@ -0,0 +1,96 @@
+use std::u32;
+
+/// A stream identifier, as described in [Section 5.1.1] of RFC 7540.
+///
+/// Streams are identified with an unsigned 31-bit integer. Streams
+/// initiated by a client MUST use odd-numbered stream identifiers; those
+/// initiated by the server MUST use even-numbered stream identifiers.  A
+/// stream identifier of zero (0x0) is used for connection control
+/// messages; the stream identifier of zero cannot be used to establish a
+/// new stream.
+///
+/// [Section 5.1.1]: https://tools.ietf.org/html/rfc7540#section-5.1.1
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
+pub struct StreamId(u32);
+
+#[derive(Debug, Copy, Clone)]
+pub struct StreamIdOverflow;
+
+const STREAM_ID_MASK: u32 = 1 << 31;
+
+impl StreamId {
+    /// Stream ID 0.
+    pub const ZERO: StreamId = StreamId(0);
+
+    /// The maximum allowed stream ID.
+    pub const MAX: StreamId = StreamId(u32::MAX >> 1);
+
+    /// Parse the stream ID
+    #[inline]
+    pub fn parse(buf: &[u8]) -> (StreamId, bool) {
+        let mut ubuf = [0; 4];
+        ubuf.copy_from_slice(&buf[0..4]);
+        let unpacked = u32::from_be_bytes(ubuf);
+        let flag = unpacked & STREAM_ID_MASK == STREAM_ID_MASK;
+
+        // Now clear the most significant bit, as that is reserved and MUST be
+        // ignored when received.
+        (StreamId(unpacked & !STREAM_ID_MASK), flag)
+    }
+
+    /// Returns true if this stream ID corresponds to a stream that
+    /// was initiated by the client.
+    pub fn is_client_initiated(&self) -> bool {
+        let id = self.0;
+        id != 0 && id % 2 == 1
+    }
+
+    /// Returns true if this stream ID corresponds to a stream that
+    /// was initiated by the server.
+    pub fn is_server_initiated(&self) -> bool {
+        let id = self.0;
+        id != 0 && id % 2 == 0
+    }
+
+    /// Return a new `StreamId` for stream 0.
+    #[inline]
+    pub fn zero() -> StreamId {
+        StreamId::ZERO
+    }
+
+    /// Returns true if this stream ID is zero.
+    pub fn is_zero(&self) -> bool {
+        self.0 == 0
+    }
+
+    /// Returns the next stream ID initiated by the same peer as this stream
+    /// ID, or an error if incrementing this stream ID would overflow the
+    /// maximum.
+    pub fn next_id(&self) -> Result<StreamId, StreamIdOverflow> {
+        let next = self.0 + 2;
+        if next > StreamId::MAX.0 {
+            Err(StreamIdOverflow)
+        } else {
+            Ok(StreamId(next))
+        }
+    }
+}
+
+impl From<u32> for StreamId {
+    fn from(src: u32) -> Self {
+        assert_eq!(src & STREAM_ID_MASK, 0, "invalid stream ID -- MSB is set");
+        StreamId(src)
+    }
+}
+
+impl From<StreamId> for u32 {
+    fn from(src: StreamId) -> Self {
+        src.0
+    }
+}
+
+impl PartialEq<u32> for StreamId {
+    fn eq(&self, other: &u32) -> bool {
+        self.0 == *other
+    }
+}
diff --git a/third_party/rust/h2/src/frame/util.rs b/third_party/rust/h2/src/frame/util.rs
new file mode 100644
index 0000000000..6bee7bd9bb
--- /dev/null
+++ b/third_party/rust/h2/src/frame/util.rs
@@ -0,0 +1,79 @@
+use std::fmt;
+
+use super::Error;
+use bytes::Bytes;
+
+/// Strip padding from the given payload.
+///
+/// It is assumed that the frame had the padded flag set. This means that the
+/// first byte is the length of the padding with that many
+/// 0 bytes expected to follow the actual payload.
+///
+/// # Returns
+///
+/// A slice of the given payload where the actual one is found and the length
+/// of the padding.
+///
+/// If the padded payload is invalid (e.g. the length of the padding is equal
+/// to the total length), returns `None`.
+pub fn strip_padding(payload: &mut Bytes) -> Result<u8, Error> {
+    let payload_len = payload.len();
+    if payload_len == 0 {
+        // If this is the case, the frame is invalid as no padding length can be
+        // extracted, even though the frame should be padded.
+        return Err(Error::TooMuchPadding);
+    }
+
+    let pad_len = payload[0] as usize;
+
+    if pad_len >= payload_len {
+        // This is invalid: the padding length MUST be less than the
+        // total frame size.
+        return Err(Error::TooMuchPadding);
+    }
+
+    let _ = payload.split_to(1);
+    let _ = payload.split_off(payload_len - pad_len - 1);
+
+    Ok(pad_len as u8)
+}
+
+pub(super) fn debug_flags<'a, 'f: 'a>(
+    fmt: &'a mut fmt::Formatter<'f>,
+    bits: u8,
+) -> DebugFlags<'a, 'f> {
+    let result = write!(fmt, "({:#x}", bits);
+    DebugFlags {
+        fmt,
+        result,
+        started: false,
+    }
+}
+
+pub(super) struct DebugFlags<'a, 'f: 'a> {
+    fmt: &'a mut fmt::Formatter<'f>,
+    result: fmt::Result,
+    started: bool,
+}
+
+impl<'a, 'f: 'a> DebugFlags<'a, 'f> {
+    pub(super) fn flag_if(&mut self, enabled: bool, name: &str) -> &mut Self {
+        if enabled {
+            self.result = self.result.and_then(|()| {
+                let prefix = if self.started {
+                    " | "
+                } else {
+                    self.started = true;
+                    ": "
+                };
+
+                write!(self.fmt, "{}{}", prefix, name)
+            });
+        }
+        self
+    }
+
+    pub(super) fn finish(&mut self) -> fmt::Result {
+        self.result.and_then(|()| write!(self.fmt, ")"))
+    }
+}
diff --git a/third_party/rust/h2/src/frame/window_update.rs b/third_party/rust/h2/src/frame/window_update.rs
new file mode 100644
index 0000000000..eed2ce17ec
--- /dev/null
+++ b/third_party/rust/h2/src/frame/window_update.rs
@@ -0,0 +1,62 @@
+use crate::frame::{self, Error, Head, Kind, StreamId};
+
+use bytes::BufMut;
+
+const SIZE_INCREMENT_MASK: u32 = 1 << 31;
+
+#[derive(Debug, Copy, Clone, Eq, PartialEq)]
+pub struct WindowUpdate {
+    stream_id: StreamId,
+    size_increment: u32,
+}
+
+impl WindowUpdate {
+    pub fn new(stream_id: StreamId, size_increment: u32) -> WindowUpdate {
+        WindowUpdate {
+            stream_id,
+            size_increment,
+        }
+    }
+
+    pub fn stream_id(&self) -> StreamId {
+        self.stream_id
+    }
+
+    pub fn size_increment(&self) -> u32 {
+        self.size_increment
+    }
+
+    /// Builds a `WindowUpdate` frame from a raw frame.
+    pub fn load(head: Head, payload: &[u8]) -> Result<WindowUpdate, Error> {
+        debug_assert_eq!(head.kind(), crate::frame::Kind::WindowUpdate);
+        if payload.len() != 4 {
+            return Err(Error::BadFrameSize);
+        }
+
+        // Clear the most significant bit, as that is reserved and MUST be ignored
+        // when received.
+        let size_increment = unpack_octets_4!(payload, 0, u32) & !SIZE_INCREMENT_MASK;
+
+        if size_increment == 0 {
+            return Err(Error::InvalidWindowUpdateValue);
+        }
+
+        Ok(WindowUpdate {
+            stream_id: head.stream_id(),
+            size_increment,
+        })
+    }
+
+    pub fn encode<B: BufMut>(&self, dst: &mut B) {
+        tracing::trace!("encoding WINDOW_UPDATE; id={:?}", self.stream_id);
+        let head = Head::new(Kind::WindowUpdate, 0, self.stream_id);
+        head.encode(4, dst);
+        dst.put_u32(self.size_increment);
+    }
+}
+
+impl<B> From<WindowUpdate> for frame::Frame<B> {
+    fn from(src: WindowUpdate) -> Self {
+        frame::Frame::WindowUpdate(src)
+    }
+}