private

hyper/src/proto/h1/decode.rs

@@ -0,0 +1,731 @@
+use std::error::Error as StdError;
+use std::fmt;
+use std::io;
+use std::usize;
+
+use bytes::Bytes;
+use tracing::{debug, trace};
+
+use crate::common::{task, Poll};
+
+use super::io::MemRead;
+use super::DecodedLength;
+
+use self::Kind::{Chunked, Eof, Length};
+
+/// Decoders to handle different Transfer-Encodings.
+///
+/// If a message body does not include a Transfer-Encoding, it *should*
+/// include a Content-Length header.
+#[derive(Clone, PartialEq)]
+pub(crate) struct Decoder {
+    kind: Kind,
+}
+
+#[derive(Debug, Clone, Copy, PartialEq)]
+enum Kind {
+    /// A Reader used when a Content-Length header is passed with a positive integer.
+    Length(u64),
+    /// A Reader used when Transfer-Encoding is `chunked`.
+    Chunked(ChunkedState, u64),
+    /// A Reader used for responses that don't indicate a length or chunked.
+    ///
+    /// The bool tracks when EOF is seen on the transport.
+    ///
+    /// Note: This should only used for `Response`s. It is illegal for a
+    /// `Request` to be made with both `Content-Length` and
+    /// `Transfer-Encoding: chunked` missing, as explained from the spec:
+    ///
+    /// > If a Transfer-Encoding header field is present in a response and
+    /// > the chunked transfer coding is not the final encoding, the
+    /// > message body length is determined by reading the connection until
+    /// > it is closed by the server.  If a Transfer-Encoding header field
+    /// > is present in a request and the chunked transfer coding is not
+    /// > the final encoding, the message body length cannot be determined
+    /// > reliably; the server MUST respond with the 400 (Bad Request)
+    /// > status code and then close the connection.
+    Eof(bool),
+}
+
+#[derive(Debug, PartialEq, Clone, Copy)]
+enum ChunkedState {
+    Size,
+    SizeLws,
+    Extension,
+    SizeLf,
+    Body,
+    BodyCr,
+    BodyLf,
+    Trailer,
+    TrailerLf,
+    EndCr,
+    EndLf,
+    End,
+}
+
+impl Decoder {
+    // constructors
+
+    pub(crate) fn length(x: u64) -> Decoder {
+        Decoder {
+            kind: Kind::Length(x),
+        }
+    }
+
+    pub(crate) fn chunked() -> Decoder {
+        Decoder {
+            kind: Kind::Chunked(ChunkedState::Size, 0),
+        }
+    }
+
+    pub(crate) fn eof() -> Decoder {
+        Decoder {
+            kind: Kind::Eof(false),
+        }
+    }
+
+    pub(super) fn new(len: DecodedLength) -> Self {
+        match len {
+            DecodedLength::CHUNKED => Decoder::chunked(),
+            DecodedLength::CLOSE_DELIMITED => Decoder::eof(),
+            length => Decoder::length(length.danger_len()),
+        }
+    }
+
+    // methods
+
+    pub(crate) fn is_eof(&self) -> bool {
+        matches!(self.kind, Length(0) | Chunked(ChunkedState::End, _) | Eof(true))
+    }
+
+    pub(crate) fn decode<R: MemRead>(
+        &mut self,
+        cx: &mut task::Context<'_>,
+        body: &mut R,
+    ) -> Poll<Result<Bytes, io::Error>> {
+        trace!("decode; state={:?}", self.kind);
+        match self.kind {
+            Length(ref mut remaining) => {
+                if *remaining == 0 {
+                    Poll::Ready(Ok(Bytes::new()))
+                } else {
+                    let to_read = *remaining as usize;
+                    let buf = ready!(body.read_mem(cx, to_read))?;
+                    let num = buf.as_ref().len() as u64;
+                    if num > *remaining {
+                        *remaining = 0;
+                    } else if num == 0 {
+                        return Poll::Ready(Err(io::Error::new(
+                            io::ErrorKind::UnexpectedEof,
+                            IncompleteBody,
+                        )));
+                    } else {
+                        *remaining -= num;
+                    }
+                    Poll::Ready(Ok(buf))
+                }
+            }
+            Chunked(ref mut state, ref mut size) => {
+                loop {
+                    let mut buf = None;
+                    // advances the chunked state
+                    *state = ready!(state.step(cx, body, size, &mut buf))?;
+                    if *state == ChunkedState::End {
+                        trace!("end of chunked");
+                        return Poll::Ready(Ok(Bytes::new()));
+                    }
+                    if let Some(buf) = buf {
+                        return Poll::Ready(Ok(buf));
+                    }
+                }
+            }
+            Eof(ref mut is_eof) => {
+                if *is_eof {
+                    Poll::Ready(Ok(Bytes::new()))
+                } else {
+                    // 8192 chosen because its about 2 packets, there probably
+                    // won't be that much available, so don't have MemReaders
+                    // allocate buffers to big
+                    body.read_mem(cx, 8192).map_ok(|slice| {
+                        *is_eof = slice.is_empty();
+                        slice
+                    })
+                }
+            }
+        }
+    }
+
+    #[cfg(test)]
+    async fn decode_fut<R: MemRead>(&mut self, body: &mut R) -> Result<Bytes, io::Error> {
+        futures_util::future::poll_fn(move |cx| self.decode(cx, body)).await
+    }
+}
+
+impl fmt::Debug for Decoder {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        fmt::Debug::fmt(&self.kind, f)
+    }
+}
+
+macro_rules! byte (
+    ($rdr:ident, $cx:expr) => ({
+        let buf = ready!($rdr.read_mem($cx, 1))?;
+        if !buf.is_empty() {
+            buf[0]
+        } else {
+            return Poll::Ready(Err(io::Error::new(io::ErrorKind::UnexpectedEof,
+                                      "unexpected EOF during chunk size line")));
+        }
+    })
+);
+
+impl ChunkedState {
+    fn step<R: MemRead>(
+        &self,
+        cx: &mut task::Context<'_>,
+        body: &mut R,
+        size: &mut u64,
+        buf: &mut Option<Bytes>,
+    ) -> Poll<Result<ChunkedState, io::Error>> {
+        use self::ChunkedState::*;
+        match *self {
+            Size => ChunkedState::read_size(cx, body, size),
+            SizeLws => ChunkedState::read_size_lws(cx, body),
+            Extension => ChunkedState::read_extension(cx, body),
+            SizeLf => ChunkedState::read_size_lf(cx, body, *size),
+            Body => ChunkedState::read_body(cx, body, size, buf),
+            BodyCr => ChunkedState::read_body_cr(cx, body),
+            BodyLf => ChunkedState::read_body_lf(cx, body),
+            Trailer => ChunkedState::read_trailer(cx, body),
+            TrailerLf => ChunkedState::read_trailer_lf(cx, body),
+            EndCr => ChunkedState::read_end_cr(cx, body),
+            EndLf => ChunkedState::read_end_lf(cx, body),
+            End => Poll::Ready(Ok(ChunkedState::End)),
+        }
+    }
+    fn read_size<R: MemRead>(
+        cx: &mut task::Context<'_>,
+        rdr: &mut R,
+        size: &mut u64,
+    ) -> Poll<Result<ChunkedState, io::Error>> {
+        trace!("Read chunk hex size");
+
+        macro_rules! or_overflow {
+            ($e:expr) => (
+                match $e {
+                    Some(val) => val,
+                    None => return Poll::Ready(Err(io::Error::new(
+                        io::ErrorKind::InvalidData,
+                        "invalid chunk size: overflow",
+                    ))),
+                }
+            )
+        }
+
+        let radix = 16;
+        match byte!(rdr, cx) {
+            b @ b'0'..=b'9' => {
+                *size = or_overflow!(size.checked_mul(radix));
+                *size = or_overflow!(size.checked_add((b - b'0') as u64));
+            }
+            b @ b'a'..=b'f' => {
+                *size = or_overflow!(size.checked_mul(radix));
+                *size = or_overflow!(size.checked_add((b + 10 - b'a') as u64));
+            }
+            b @ b'A'..=b'F' => {
+                *size = or_overflow!(size.checked_mul(radix));
+                *size = or_overflow!(size.checked_add((b + 10 - b'A') as u64));
+            }
+            b'\t' | b' ' => return Poll::Ready(Ok(ChunkedState::SizeLws)),
+            b';' => return Poll::Ready(Ok(ChunkedState::Extension)),
+            b'\r' => return Poll::Ready(Ok(ChunkedState::SizeLf)),
+            _ => {
+                return Poll::Ready(Err(io::Error::new(
+                    io::ErrorKind::InvalidInput,
+                    "Invalid chunk size line: Invalid Size",
+                )));
+            }
+        }
+        Poll::Ready(Ok(ChunkedState::Size))
+    }
+    fn read_size_lws<R: MemRead>(
+        cx: &mut task::Context<'_>,
+        rdr: &mut R,
+    ) -> Poll<Result<ChunkedState, io::Error>> {
+        trace!("read_size_lws");
+        match byte!(rdr, cx) {
+            // LWS can follow the chunk size, but no more digits can come
+            b'\t' | b' ' => Poll::Ready(Ok(ChunkedState::SizeLws)),
+            b';' => Poll::Ready(Ok(ChunkedState::Extension)),
+            b'\r' => Poll::Ready(Ok(ChunkedState::SizeLf)),
+            _ => Poll::Ready(Err(io::Error::new(
+                io::ErrorKind::InvalidInput,
+                "Invalid chunk size linear white space",
+            ))),
+        }
+    }
+    fn read_extension<R: MemRead>(
+        cx: &mut task::Context<'_>,
+        rdr: &mut R,
+    ) -> Poll<Result<ChunkedState, io::Error>> {
+        trace!("read_extension");
+        // We don't care about extensions really at all. Just ignore them.
+        // They "end" at the next CRLF.
+        //
+        // However, some implementations may not check for the CR, so to save
+        // them from themselves, we reject extensions containing plain LF as
+        // well.
+        match byte!(rdr, cx) {
+            b'\r' => Poll::Ready(Ok(ChunkedState::SizeLf)),
+            b'\n' => Poll::Ready(Err(io::Error::new(
+                io::ErrorKind::InvalidData,
+                "invalid chunk extension contains newline",
+            ))),
+            _ => Poll::Ready(Ok(ChunkedState::Extension)), // no supported extensions
+        }
+    }
+    fn read_size_lf<R: MemRead>(
+        cx: &mut task::Context<'_>,
+        rdr: &mut R,
+        size: u64,
+    ) -> Poll<Result<ChunkedState, io::Error>> {
+        trace!("Chunk size is {:?}", size);
+        match byte!(rdr, cx) {
+            b'\n' => {
+                if size == 0 {
+                    Poll::Ready(Ok(ChunkedState::EndCr))
+                } else {
+                    debug!("incoming chunked header: {0:#X} ({0} bytes)", size);
+                    Poll::Ready(Ok(ChunkedState::Body))
+                }
+            }
+            _ => Poll::Ready(Err(io::Error::new(
+                io::ErrorKind::InvalidInput,
+                "Invalid chunk size LF",
+            ))),
+        }
+    }
+
+    fn read_body<R: MemRead>(
+        cx: &mut task::Context<'_>,
+        rdr: &mut R,
+        rem: &mut u64,
+        buf: &mut Option<Bytes>,
+    ) -> Poll<Result<ChunkedState, io::Error>> {
+        trace!("Chunked read, remaining={:?}", rem);
+
+        // cap remaining bytes at the max capacity of usize
+        let rem_cap = match *rem {
+            r if r > usize::MAX as u64 => usize::MAX,
+            r => r as usize,
+        };
+
+        let to_read = rem_cap;
+        let slice = ready!(rdr.read_mem(cx, to_read))?;
+        let count = slice.len();
+
+        if count == 0 {
+            *rem = 0;
+            return Poll::Ready(Err(io::Error::new(
+                io::ErrorKind::UnexpectedEof,
+                IncompleteBody,
+            )));
+        }
+        *buf = Some(slice);
+        *rem -= count as u64;
+
+        if *rem > 0 {
+            Poll::Ready(Ok(ChunkedState::Body))
+        } else {
+            Poll::Ready(Ok(ChunkedState::BodyCr))
+        }
+    }
+    fn read_body_cr<R: MemRead>(
+        cx: &mut task::Context<'_>,
+        rdr: &mut R,
+    ) -> Poll<Result<ChunkedState, io::Error>> {
+        match byte!(rdr, cx) {
+            b'\r' => Poll::Ready(Ok(ChunkedState::BodyLf)),
+            _ => Poll::Ready(Err(io::Error::new(
+                io::ErrorKind::InvalidInput,
+                "Invalid chunk body CR",
+            ))),
+        }
+    }
+    fn read_body_lf<R: MemRead>(
+        cx: &mut task::Context<'_>,
+        rdr: &mut R,
+    ) -> Poll<Result<ChunkedState, io::Error>> {
+        match byte!(rdr, cx) {
+            b'\n' => Poll::Ready(Ok(ChunkedState::Size)),
+            _ => Poll::Ready(Err(io::Error::new(
+                io::ErrorKind::InvalidInput,
+                "Invalid chunk body LF",
+            ))),
+        }
+    }
+
+    fn read_trailer<R: MemRead>(
+        cx: &mut task::Context<'_>,
+        rdr: &mut R,
+    ) -> Poll<Result<ChunkedState, io::Error>> {
+        trace!("read_trailer");
+        match byte!(rdr, cx) {
+            b'\r' => Poll::Ready(Ok(ChunkedState::TrailerLf)),
+            _ => Poll::Ready(Ok(ChunkedState::Trailer)),
+        }
+    }
+    fn read_trailer_lf<R: MemRead>(
+        cx: &mut task::Context<'_>,
+        rdr: &mut R,
+    ) -> Poll<Result<ChunkedState, io::Error>> {
+        match byte!(rdr, cx) {
+            b'\n' => Poll::Ready(Ok(ChunkedState::EndCr)),
+            _ => Poll::Ready(Err(io::Error::new(
+                io::ErrorKind::InvalidInput,
+                "Invalid trailer end LF",
+            ))),
+        }
+    }
+
+    fn read_end_cr<R: MemRead>(
+        cx: &mut task::Context<'_>,
+        rdr: &mut R,
+    ) -> Poll<Result<ChunkedState, io::Error>> {
+        match byte!(rdr, cx) {
+            b'\r' => Poll::Ready(Ok(ChunkedState::EndLf)),
+            _ => Poll::Ready(Ok(ChunkedState::Trailer)),
+        }
+    }
+    fn read_end_lf<R: MemRead>(
+        cx: &mut task::Context<'_>,
+        rdr: &mut R,
+    ) -> Poll<Result<ChunkedState, io::Error>> {
+        match byte!(rdr, cx) {
+            b'\n' => Poll::Ready(Ok(ChunkedState::End)),
+            _ => Poll::Ready(Err(io::Error::new(
+                io::ErrorKind::InvalidInput,
+                "Invalid chunk end LF",
+            ))),
+        }
+    }
+}
+
+#[derive(Debug)]
+struct IncompleteBody;
+
+impl fmt::Display for IncompleteBody {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "end of file before message length reached")
+    }
+}
+
+impl StdError for IncompleteBody {}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::pin::Pin;
+    use std::time::Duration;
+    use tokio::io::{AsyncRead, ReadBuf};
+
+    impl<'a> MemRead for &'a [u8] {
+        fn read_mem(&mut self, _: &mut task::Context<'_>, len: usize) -> Poll<io::Result<Bytes>> {
+            let n = std::cmp::min(len, self.len());
+            if n > 0 {
+                let (a, b) = self.split_at(n);
+                let buf = Bytes::copy_from_slice(a);
+                *self = b;
+                Poll::Ready(Ok(buf))
+            } else {
+                Poll::Ready(Ok(Bytes::new()))
+            }
+        }
+    }
+
+    impl<'a> MemRead for &'a mut (dyn AsyncRead + Unpin) {
+        fn read_mem(&mut self, cx: &mut task::Context<'_>, len: usize) -> Poll<io::Result<Bytes>> {
+            let mut v = vec![0; len];
+            let mut buf = ReadBuf::new(&mut v);
+            ready!(Pin::new(self).poll_read(cx, &mut buf)?);
+            Poll::Ready(Ok(Bytes::copy_from_slice(&buf.filled())))
+        }
+    }
+
+    #[cfg(feature = "nightly")]
+    impl MemRead for Bytes {
+        fn read_mem(&mut self, _: &mut task::Context<'_>, len: usize) -> Poll<io::Result<Bytes>> {
+            let n = std::cmp::min(len, self.len());
+            let ret = self.split_to(n);
+            Poll::Ready(Ok(ret))
+        }
+    }
+
+    /*
+    use std::io;
+    use std::io::Write;
+    use super::Decoder;
+    use super::ChunkedState;
+    use futures::{Async, Poll};
+    use bytes::{BytesMut, Bytes};
+    use crate::mock::AsyncIo;
+    */
+
+    #[tokio::test]
+    async fn test_read_chunk_size() {
+        use std::io::ErrorKind::{InvalidData, InvalidInput, UnexpectedEof};
+
+        async fn read(s: &str) -> u64 {
+            let mut state = ChunkedState::Size;
+            let rdr = &mut s.as_bytes();
+            let mut size = 0;
+            loop {
+                let result =
+                    futures_util::future::poll_fn(|cx| state.step(cx, rdr, &mut size, &mut None))
+                        .await;
+                let desc = format!("read_size failed for {:?}", s);
+                state = result.expect(desc.as_str());
+                if state == ChunkedState::Body || state == ChunkedState::EndCr {
+                    break;
+                }
+            }
+            size
+        }
+
+        async fn read_err(s: &str, expected_err: io::ErrorKind) {
+            let mut state = ChunkedState::Size;
+            let rdr = &mut s.as_bytes();
+            let mut size = 0;
+            loop {
+                let result =
+                    futures_util::future::poll_fn(|cx| state.step(cx, rdr, &mut size, &mut None))
+                        .await;
+                state = match result {
+                    Ok(s) => s,
+                    Err(e) => {
+                        assert!(
+                            expected_err == e.kind(),
+                            "Reading {:?}, expected {:?}, but got {:?}",
+                            s,
+                            expected_err,
+                            e.kind()
+                        );
+                        return;
+                    }
+                };
+                if state == ChunkedState::Body || state == ChunkedState::End {
+                    panic!("Was Ok. Expected Err for {:?}", s);
+                }
+            }
+        }
+
+        assert_eq!(1, read("1\r\n").await);
+        assert_eq!(1, read("01\r\n").await);
+        assert_eq!(0, read("0\r\n").await);
+        assert_eq!(0, read("00\r\n").await);
+        assert_eq!(10, read("A\r\n").await);
+        assert_eq!(10, read("a\r\n").await);
+        assert_eq!(255, read("Ff\r\n").await);
+        assert_eq!(255, read("Ff   \r\n").await);
+        // Missing LF or CRLF
+        read_err("F\rF", InvalidInput).await;
+        read_err("F", UnexpectedEof).await;
+        // Invalid hex digit
+        read_err("X\r\n", InvalidInput).await;
+        read_err("1X\r\n", InvalidInput).await;
+        read_err("-\r\n", InvalidInput).await;
+        read_err("-1\r\n", InvalidInput).await;
+        // Acceptable (if not fully valid) extensions do not influence the size
+        assert_eq!(1, read("1;extension\r\n").await);
+        assert_eq!(10, read("a;ext name=value\r\n").await);
+        assert_eq!(1, read("1;extension;extension2\r\n").await);
+        assert_eq!(1, read("1;;;  ;\r\n").await);
+        assert_eq!(2, read("2; extension...\r\n").await);
+        assert_eq!(3, read("3   ; extension=123\r\n").await);
+        assert_eq!(3, read("3   ;\r\n").await);
+        assert_eq!(3, read("3   ;   \r\n").await);
+        // Invalid extensions cause an error
+        read_err("1 invalid extension\r\n", InvalidInput).await;
+        read_err("1 A\r\n", InvalidInput).await;
+        read_err("1;no CRLF", UnexpectedEof).await;
+        read_err("1;reject\nnewlines\r\n", InvalidData).await;
+        // Overflow
+        read_err("f0000000000000003\r\n", InvalidData).await;
+    }
+
+    #[tokio::test]
+    async fn test_read_sized_early_eof() {
+        let mut bytes = &b"foo bar"[..];
+        let mut decoder = Decoder::length(10);
+        assert_eq!(decoder.decode_fut(&mut bytes).await.unwrap().len(), 7);
+        let e = decoder.decode_fut(&mut bytes).await.unwrap_err();
+        assert_eq!(e.kind(), io::ErrorKind::UnexpectedEof);
+    }
+
+    #[tokio::test]
+    async fn test_read_chunked_early_eof() {
+        let mut bytes = &b"\
+            9\r\n\
+            foo bar\
+        "[..];
+        let mut decoder = Decoder::chunked();
+        assert_eq!(decoder.decode_fut(&mut bytes).await.unwrap().len(), 7);
+        let e = decoder.decode_fut(&mut bytes).await.unwrap_err();
+        assert_eq!(e.kind(), io::ErrorKind::UnexpectedEof);
+    }
+
+    #[tokio::test]
+    async fn test_read_chunked_single_read() {
+        let mut mock_buf = &b"10\r\n1234567890abcdef\r\n0\r\n"[..];
+        let buf = Decoder::chunked()
+            .decode_fut(&mut mock_buf)
+            .await
+            .expect("decode");
+        assert_eq!(16, buf.len());
+        let result = String::from_utf8(buf.as_ref().to_vec()).expect("decode String");
+        assert_eq!("1234567890abcdef", &result);
+    }
+
+    #[tokio::test]
+    async fn test_read_chunked_trailer_with_missing_lf() {
+        let mut mock_buf = &b"10\r\n1234567890abcdef\r\n0\r\nbad\r\r\n"[..];
+        let mut decoder = Decoder::chunked();
+        decoder.decode_fut(&mut mock_buf).await.expect("decode");
+        let e = decoder.decode_fut(&mut mock_buf).await.unwrap_err();
+        assert_eq!(e.kind(), io::ErrorKind::InvalidInput);
+    }
+
+    #[tokio::test]
+    async fn test_read_chunked_after_eof() {
+        let mut mock_buf = &b"10\r\n1234567890abcdef\r\n0\r\n\r\n"[..];
+        let mut decoder = Decoder::chunked();
+
+        // normal read
+        let buf = decoder.decode_fut(&mut mock_buf).await.unwrap();
+        assert_eq!(16, buf.len());
+        let result = String::from_utf8(buf.as_ref().to_vec()).expect("decode String");
+        assert_eq!("1234567890abcdef", &result);
+
+        // eof read
+        let buf = decoder.decode_fut(&mut mock_buf).await.expect("decode");
+        assert_eq!(0, buf.len());
+
+        // ensure read after eof also returns eof
+        let buf = decoder.decode_fut(&mut mock_buf).await.expect("decode");
+        assert_eq!(0, buf.len());
+    }
+
+    // perform an async read using a custom buffer size and causing a blocking
+    // read at the specified byte
+    async fn read_async(mut decoder: Decoder, content: &[u8], block_at: usize) -> String {
+        let mut outs = Vec::new();
+
+        let mut ins = if block_at == 0 {
+            tokio_test::io::Builder::new()
+                .wait(Duration::from_millis(10))
+                .read(content)
+                .build()
+        } else {
+            tokio_test::io::Builder::new()
+                .read(&content[..block_at])
+                .wait(Duration::from_millis(10))
+                .read(&content[block_at..])
+                .build()
+        };
+
+        let mut ins = &mut ins as &mut (dyn AsyncRead + Unpin);
+
+        loop {
+            let buf = decoder
+                .decode_fut(&mut ins)
+                .await
+                .expect("unexpected decode error");
+            if buf.is_empty() {
+                break; // eof
+            }
+            outs.extend(buf.as_ref());
+        }
+
+        String::from_utf8(outs).expect("decode String")
+    }
+
+    // iterate over the different ways that this async read could go.
+    // tests blocking a read at each byte along the content - The shotgun approach
+    async fn all_async_cases(content: &str, expected: &str, decoder: Decoder) {
+        let content_len = content.len();
+        for block_at in 0..content_len {
+            let actual = read_async(decoder.clone(), content.as_bytes(), block_at).await;
+            assert_eq!(expected, &actual) //, "Failed async. Blocking at {}", block_at);
+        }
+    }
+
+    #[tokio::test]
+    async fn test_read_length_async() {
+        let content = "foobar";
+        all_async_cases(content, content, Decoder::length(content.len() as u64)).await;
+    }
+
+    #[tokio::test]
+    async fn test_read_chunked_async() {
+        let content = "3\r\nfoo\r\n3\r\nbar\r\n0\r\n\r\n";
+        let expected = "foobar";
+        all_async_cases(content, expected, Decoder::chunked()).await;
+    }
+
+    #[tokio::test]
+    async fn test_read_eof_async() {
+        let content = "foobar";
+        all_async_cases(content, content, Decoder::eof()).await;
+    }
+
+    #[cfg(feature = "nightly")]
+    #[bench]
+    fn bench_decode_chunked_1kb(b: &mut test::Bencher) {
+        let rt = new_runtime();
+
+        const LEN: usize = 1024;
+        let mut vec = Vec::new();
+        vec.extend(format!("{:x}\r\n", LEN).as_bytes());
+        vec.extend(&[0; LEN][..]);
+        vec.extend(b"\r\n");
+        let content = Bytes::from(vec);
+
+        b.bytes = LEN as u64;
+
+        b.iter(|| {
+            let mut decoder = Decoder::chunked();
+            rt.block_on(async {
+                let mut raw = content.clone();
+                let chunk = decoder.decode_fut(&mut raw).await.unwrap();
+                assert_eq!(chunk.len(), LEN);
+            });
+        });
+    }
+
+    #[cfg(feature = "nightly")]
+    #[bench]
+    fn bench_decode_length_1kb(b: &mut test::Bencher) {
+        let rt = new_runtime();
+
+        const LEN: usize = 1024;
+        let content = Bytes::from(&[0; LEN][..]);
+        b.bytes = LEN as u64;
+
+        b.iter(|| {
+            let mut decoder = Decoder::length(LEN as u64);
+            rt.block_on(async {
+                let mut raw = content.clone();
+                let chunk = decoder.decode_fut(&mut raw).await.unwrap();
+                assert_eq!(chunk.len(), LEN);
+            });
+        });
+    }
+
+    #[cfg(feature = "nightly")]
+    fn new_runtime() -> tokio::runtime::Runtime {
+        tokio::runtime::Builder::new_current_thread()
+            .enable_all()
+            .build()
+            .expect("rt build")
+    }
+}

hyper/src/proto/h1/dispatch.rs

@@ -0,0 +1,750 @@
+use std::error::Error as StdError;
+
+use bytes::{Buf, Bytes};
+use http::Request;
+use tokio::io::{AsyncRead, AsyncWrite};
+use tracing::{debug, trace};
+
+use super::{Http1Transaction, Wants};
+use crate::body::{Body, DecodedLength, HttpBody};
+use crate::common::{task, Future, Pin, Poll, Unpin};
+use crate::proto::{
+    BodyLength, Conn, Dispatched, MessageHead, RequestHead,
+};
+use crate::upgrade::OnUpgrade;
+
+pub(crate) struct Dispatcher<D, Bs: HttpBody, I, T> {
+    conn: Conn<I, Bs::Data, T>,
+    dispatch: D,
+    body_tx: Option<crate::body::Sender>,
+    body_rx: Pin<Box<Option<Bs>>>,
+    is_closing: bool,
+}
+
+pub(crate) trait Dispatch {
+    type PollItem;
+    type PollBody;
+    type PollError;
+    type RecvItem;
+    fn poll_msg(
+        self: Pin<&mut Self>,
+        cx: &mut task::Context<'_>,
+    ) -> Poll<Option<Result<(Self::PollItem, Self::PollBody), Self::PollError>>>;
+    fn recv_msg(&mut self, msg: crate::Result<(Self::RecvItem, Body)>) -> crate::Result<()>;
+    fn poll_ready(&mut self, cx: &mut task::Context<'_>) -> Poll<Result<(), ()>>;
+    fn should_poll(&self) -> bool;
+}
+
+cfg_server! {
+    use crate::service::HttpService;
+
+    pub(crate) struct Server<S: HttpService<B>, B> {
+        in_flight: Pin<Box<Option<S::Future>>>,
+        pub(crate) service: S,
+    }
+}
+
+cfg_client! {
+    pin_project_lite::pin_project! {
+        pub(crate) struct Client<B> {
+            callback: Option<crate::client::dispatch::Callback<Request<B>, http::Response<Body>>>,
+            #[pin]
+            rx: ClientRx<B>,
+            rx_closed: bool,
+        }
+    }
+
+    type ClientRx<B> = crate::client::dispatch::Receiver<Request<B>, http::Response<Body>>;
+}
+
+impl<D, Bs, I, T> Dispatcher<D, Bs, I, T>
+where
+    D: Dispatch<
+        PollItem = MessageHead<T::Outgoing>,
+        PollBody = Bs,
+        RecvItem = MessageHead<T::Incoming>,
+    > + Unpin,
+    D::PollError: Into<Box<dyn StdError + Send + Sync>>,
+    I: AsyncRead + AsyncWrite + Unpin,
+    T: Http1Transaction + Unpin,
+    Bs: HttpBody + 'static,
+    Bs::Error: Into<Box<dyn StdError + Send + Sync>>,
+{
+    pub(crate) fn new(dispatch: D, conn: Conn<I, Bs::Data, T>) -> Self {
+        Dispatcher {
+            conn,
+            dispatch,
+            body_tx: None,
+            body_rx: Box::pin(None),
+            is_closing: false,
+        }
+    }
+
+    #[cfg(feature = "server")]
+    pub(crate) fn disable_keep_alive(&mut self) {
+        self.conn.disable_keep_alive();
+        if self.conn.is_write_closed() {
+            self.close();
+        }
+    }
+
+    pub(crate) fn into_inner(self) -> (I, Bytes, D) {
+        let (io, buf) = self.conn.into_inner();
+        (io, buf, self.dispatch)
+    }
+
+    /// Run this dispatcher until HTTP says this connection is done,
+    /// but don't call `AsyncWrite::shutdown` on the underlying IO.
+    ///
+    /// This is useful for old-style HTTP upgrades, but ignores
+    /// newer-style upgrade API.
+    pub(crate) fn poll_without_shutdown(
+        &mut self,
+        cx: &mut task::Context<'_>,
+    ) -> Poll<crate::Result<()>>
+    where
+        Self: Unpin,
+    {
+        Pin::new(self).poll_catch(cx, false).map_ok(|ds| {
+            if let Dispatched::Upgrade(pending) = ds {
+                pending.manual();
+            }
+        })
+    }
+
+    fn poll_catch(
+        &mut self,
+        cx: &mut task::Context<'_>,
+        should_shutdown: bool,
+    ) -> Poll<crate::Result<Dispatched>> {
+        Poll::Ready(ready!(self.poll_inner(cx, should_shutdown)).or_else(|e| {
+            // An error means we're shutting down either way.
+            // We just try to give the error to the user,
+            // and close the connection with an Ok. If we
+            // cannot give it to the user, then return the Err.
+            self.dispatch.recv_msg(Err(e))?;
+            Ok(Dispatched::Shutdown)
+        }))
+    }
+
+    fn poll_inner(
+        &mut self,
+        cx: &mut task::Context<'_>,
+        should_shutdown: bool,
+    ) -> Poll<crate::Result<Dispatched>> {
+        T::update_date();
+
+        ready!(self.poll_loop(cx))?;
+
+        if self.is_done() {
+            if let Some(pending) = self.conn.pending_upgrade() {
+                self.conn.take_error()?;
+                return Poll::Ready(Ok(Dispatched::Upgrade(pending)));
+            } else if should_shutdown {
+                ready!(self.conn.poll_shutdown(cx)).map_err(crate::Error::new_shutdown)?;
+            }
+            self.conn.take_error()?;
+            Poll::Ready(Ok(Dispatched::Shutdown))
+        } else {
+            Poll::Pending
+        }
+    }
+
+    fn poll_loop(&mut self, cx: &mut task::Context<'_>) -> Poll<crate::Result<()>> {
+        // Limit the looping on this connection, in case it is ready far too
+        // often, so that other futures don't starve.
+        //
+        // 16 was chosen arbitrarily, as that is number of pipelined requests
+        // benchmarks often use. Perhaps it should be a config option instead.
+        for _ in 0..16 {
+            let _ = self.poll_read(cx)?;
+            let _ = self.poll_write(cx)?;
+            let _ = self.poll_flush(cx)?;
+
+            // This could happen if reading paused before blocking on IO,
+            // such as getting to the end of a framed message, but then
+            // writing/flushing set the state back to Init. In that case,
+            // if the read buffer still had bytes, we'd want to try poll_read
+            // again, or else we wouldn't ever be woken up again.
+            //
+            // Using this instead of task::current() and notify() inside
+            // the Conn is noticeably faster in pipelined benchmarks.
+            if !self.conn.wants_read_again() {
+                //break;
+                return Poll::Ready(Ok(()));
+            }
+        }
+
+        trace!("poll_loop yielding (self = {:p})", self);
+
+        task::yield_now(cx).map(|never| match never {})
+    }
+
+    fn poll_read(&mut self, cx: &mut task::Context<'_>) -> Poll<crate::Result<()>> {
+        loop {
+            if self.is_closing {
+                return Poll::Ready(Ok(()));
+            } else if self.conn.can_read_head() {
+                ready!(self.poll_read_head(cx))?;
+            } else if let Some(mut body) = self.body_tx.take() {
+                if self.conn.can_read_body() {
+                    match body.poll_ready(cx) {
+                        Poll::Ready(Ok(())) => (),
+                        Poll::Pending => {
+                            self.body_tx = Some(body);
+                            return Poll::Pending;
+                        }
+                        Poll::Ready(Err(_canceled)) => {
+                            // user doesn't care about the body
+                            // so we should stop reading
+                            trace!("body receiver dropped before eof, draining or closing");
+                            self.conn.poll_drain_or_close_read(cx);
+                            continue;
+                        }
+                    }
+                    match self.conn.poll_read_body(cx) {
+                        Poll::Ready(Some(Ok(chunk))) => match body.try_send_data(chunk) {
+                            Ok(()) => {
+                                self.body_tx = Some(body);
+                            }
+                            Err(_canceled) => {
+                                if self.conn.can_read_body() {
+                                    trace!("body receiver dropped before eof, closing");
+                                    self.conn.close_read();
+                                }
+                            }
+                        },
+                        Poll::Ready(None) => {
+                            // just drop, the body will close automatically
+                        }
+                        Poll::Pending => {
+                            self.body_tx = Some(body);
+                            return Poll::Pending;
+                        }
+                        Poll::Ready(Some(Err(e))) => {
+                            body.send_error(crate::Error::new_body(e));
+                        }
+                    }
+                } else {
+                    // just drop, the body will close automatically
+                }
+            } else {
+                return self.conn.poll_read_keep_alive(cx);
+            }
+        }
+    }
+
+    fn poll_read_head(&mut self, cx: &mut task::Context<'_>) -> Poll<crate::Result<()>> {
+        // can dispatch receive, or does it still care about, an incoming message?
+        match ready!(self.dispatch.poll_ready(cx)) {
+            Ok(()) => (),
+            Err(()) => {
+                trace!("dispatch no longer receiving messages");
+                self.close();
+                return Poll::Ready(Ok(()));
+            }
+        }
+        // dispatch is ready for a message, try to read one
+        match ready!(self.conn.poll_read_head(cx)) {
+            Some(Ok((mut head, body_len, wants))) => {
+                let body = match body_len {
+                    DecodedLength::ZERO => Body::empty(),
+                    other => {
+                        let (tx, rx) = Body::new_channel(other, wants.contains(Wants::EXPECT));
+                        self.body_tx = Some(tx);
+                        rx
+                    }
+                };
+                if wants.contains(Wants::UPGRADE) {
+                    let upgrade = self.conn.on_upgrade();
+                    debug_assert!(!upgrade.is_none(), "empty upgrade");
+                    debug_assert!(head.extensions.get::<OnUpgrade>().is_none(), "OnUpgrade already set");
+                    head.extensions.insert(upgrade);
+                }
+                self.dispatch.recv_msg(Ok((head, body)))?;
+                Poll::Ready(Ok(()))
+            }
+            Some(Err(err)) => {
+                debug!("read_head error: {}", err);
+                self.dispatch.recv_msg(Err(err))?;
+                // if here, the dispatcher gave the user the error
+                // somewhere else. we still need to shutdown, but
+                // not as a second error.
+                self.close();
+                Poll::Ready(Ok(()))
+            }
+            None => {
+                // read eof, the write side will have been closed too unless
+                // allow_read_close was set to true, in which case just do
+                // nothing...
+                debug_assert!(self.conn.is_read_closed());
+                if self.conn.is_write_closed() {
+                    self.close();
+                }
+                Poll::Ready(Ok(()))
+            }
+        }
+    }
+
+    fn poll_write(&mut self, cx: &mut task::Context<'_>) -> Poll<crate::Result<()>> {
+        loop {
+            if self.is_closing {
+                return Poll::Ready(Ok(()));
+            } else if self.body_rx.is_none()
+                && self.conn.can_write_head()
+                && self.dispatch.should_poll()
+            {
+                if let Some(msg) = ready!(Pin::new(&mut self.dispatch).poll_msg(cx)) {
+                    let (head, mut body) = msg.map_err(crate::Error::new_user_service)?;
+
+                    // Check if the body knows its full data immediately.
+                    //
+                    // If so, we can skip a bit of bookkeeping that streaming
+                    // bodies need to do.
+                    if let Some(full) = crate::body::take_full_data(&mut body) {
+                        self.conn.write_full_msg(head, full);
+                        return Poll::Ready(Ok(()));
+                    }
+
+                    let body_type = if body.is_end_stream() {
+                        self.body_rx.set(None);
+                        None
+                    } else {
+                        let btype = body
+                            .size_hint()
+                            .exact()
+                            .map(BodyLength::Known)
+                            .or_else(|| Some(BodyLength::Unknown));
+                        self.body_rx.set(Some(body));
+                        btype
+                    };
+                    self.conn.write_head(head, body_type);
+                } else {
+                    self.close();
+                    return Poll::Ready(Ok(()));
+                }
+            } else if !self.conn.can_buffer_body() {
+                ready!(self.poll_flush(cx))?;
+            } else {
+                // A new scope is needed :(
+                if let (Some(mut body), clear_body) =
+                    OptGuard::new(self.body_rx.as_mut()).guard_mut()
+                {
+                    debug_assert!(!*clear_body, "opt guard defaults to keeping body");
+                    if !self.conn.can_write_body() {
+                        trace!(
+                            "no more write body allowed, user body is_end_stream = {}",
+                            body.is_end_stream(),
+                        );
+                        *clear_body = true;
+                        continue;
+                    }
+
+                    let item = ready!(body.as_mut().poll_data(cx));
+                    if let Some(item) = item {
+                        let chunk = item.map_err(|e| {
+                            *clear_body = true;
+                            crate::Error::new_user_body(e)
+                        })?;
+                        let eos = body.is_end_stream();
+                        if eos {
+                            *clear_body = true;
+                            if chunk.remaining() == 0 {
+                                trace!("discarding empty chunk");
+                                self.conn.end_body()?;
+                            } else {
+                                self.conn.write_body_and_end(chunk);
+                            }
+                        } else {
+                            if chunk.remaining() == 0 {
+                                trace!("discarding empty chunk");
+                                continue;
+                            }
+                            self.conn.write_body(chunk);
+                        }
+                    } else {
+                        *clear_body = true;
+                        self.conn.end_body()?;
+                    }
+                } else {
+                    return Poll::Pending;
+                }
+            }
+        }
+    }
+
+    fn poll_flush(&mut self, cx: &mut task::Context<'_>) -> Poll<crate::Result<()>> {
+        self.conn.poll_flush(cx).map_err(|err| {
+            debug!("error writing: {}", err);
+            crate::Error::new_body_write(err)
+        })
+    }
+
+    fn close(&mut self) {
+        self.is_closing = true;
+        self.conn.close_read();
+        self.conn.close_write();
+    }
+
+    fn is_done(&self) -> bool {
+        if self.is_closing {
+            return true;
+        }
+
+        let read_done = self.conn.is_read_closed();
+
+        if !T::should_read_first() && read_done {
+            // a client that cannot read may was well be done.
+            true
+        } else {
+            let write_done = self.conn.is_write_closed()
+                || (!self.dispatch.should_poll() && self.body_rx.is_none());
+            read_done && write_done
+        }
+    }
+}
+
+impl<D, Bs, I, T> Future for Dispatcher<D, Bs, I, T>
+where
+    D: Dispatch<
+        PollItem = MessageHead<T::Outgoing>,
+        PollBody = Bs,
+        RecvItem = MessageHead<T::Incoming>,
+    > + Unpin,
+    D::PollError: Into<Box<dyn StdError + Send + Sync>>,
+    I: AsyncRead + AsyncWrite + Unpin,
+    T: Http1Transaction + Unpin,
+    Bs: HttpBody + 'static,
+    Bs::Error: Into<Box<dyn StdError + Send + Sync>>,
+{
+    type Output = crate::Result<Dispatched>;
+
+    #[inline]
+    fn poll(mut self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Self::Output> {
+        self.poll_catch(cx, true)
+    }
+}
+
+// ===== impl OptGuard =====
+
+/// A drop guard to allow a mutable borrow of an Option while being able to
+/// set whether the `Option` should be cleared on drop.
+struct OptGuard<'a, T>(Pin<&'a mut Option<T>>, bool);
+
+impl<'a, T> OptGuard<'a, T> {
+    fn new(pin: Pin<&'a mut Option<T>>) -> Self {
+        OptGuard(pin, false)
+    }
+
+    fn guard_mut(&mut self) -> (Option<Pin<&mut T>>, &mut bool) {
+        (self.0.as_mut().as_pin_mut(), &mut self.1)
+    }
+}
+
+impl<'a, T> Drop for OptGuard<'a, T> {
+    fn drop(&mut self) {
+        if self.1 {
+            self.0.set(None);
+        }
+    }
+}
+
+// ===== impl Server =====
+
+cfg_server! {
+    impl<S, B> Server<S, B>
+    where
+        S: HttpService<B>,
+    {
+        pub(crate) fn new(service: S) -> Server<S, B> {
+            Server {
+                in_flight: Box::pin(None),
+                service,
+            }
+        }
+
+        pub(crate) fn into_service(self) -> S {
+            self.service
+        }
+    }
+
+    // Service is never pinned
+    impl<S: HttpService<B>, B> Unpin for Server<S, B> {}
+
+    impl<S, Bs> Dispatch for Server<S, Body>
+    where
+        S: HttpService<Body, ResBody = Bs>,
+        S::Error: Into<Box<dyn StdError + Send + Sync>>,
+        Bs: HttpBody,
+    {
+        type PollItem = MessageHead<http::StatusCode>;
+        type PollBody = Bs;
+        type PollError = S::Error;
+        type RecvItem = RequestHead;
+
+        fn poll_msg(
+            mut self: Pin<&mut Self>,
+            cx: &mut task::Context<'_>,
+        ) -> Poll<Option<Result<(Self::PollItem, Self::PollBody), Self::PollError>>> {
+            let mut this = self.as_mut();
+            let ret = if let Some(ref mut fut) = this.in_flight.as_mut().as_pin_mut() {
+                let resp = ready!(fut.as_mut().poll(cx)?);
+                let (parts, body) = resp.into_parts();
+                let head = MessageHead {
+                    version: parts.version,
+                    subject: parts.status,
+                    headers: parts.headers,
+                    extensions: parts.extensions,
+                };
+                Poll::Ready(Some(Ok((head, body))))
+            } else {
+                unreachable!("poll_msg shouldn't be called if no inflight");
+            };
+
+            // Since in_flight finished, remove it
+            this.in_flight.set(None);
+            ret
+        }
+
+        fn recv_msg(&mut self, msg: crate::Result<(Self::RecvItem, Body)>) -> crate::Result<()> {
+            let (msg, body) = msg?;
+            let mut req = Request::new(body);
+            *req.method_mut() = msg.subject.0;
+            *req.uri_mut() = msg.subject.1;
+            *req.headers_mut() = msg.headers;
+            *req.version_mut() = msg.version;
+            *req.extensions_mut() = msg.extensions;
+            let fut = self.service.call(req);
+            self.in_flight.set(Some(fut));
+            Ok(())
+        }
+
+        fn poll_ready(&mut self, cx: &mut task::Context<'_>) -> Poll<Result<(), ()>> {
+            if self.in_flight.is_some() {
+                Poll::Pending
+            } else {
+                self.service.poll_ready(cx).map_err(|_e| {
+                    // FIXME: return error value.
+                    trace!("service closed");
+                })
+            }
+        }
+
+        fn should_poll(&self) -> bool {
+            self.in_flight.is_some()
+        }
+    }
+}
+
+// ===== impl Client =====
+
+cfg_client! {
+    impl<B> Client<B> {
+        pub(crate) fn new(rx: ClientRx<B>) -> Client<B> {
+            Client {
+                callback: None,
+                rx,
+                rx_closed: false,
+            }
+        }
+    }
+
+    impl<B> Dispatch for Client<B>
+    where
+        B: HttpBody,
+    {
+        type PollItem = RequestHead;
+        type PollBody = B;
+        type PollError = crate::common::Never;
+        type RecvItem = crate::proto::ResponseHead;
+
+        fn poll_msg(
+            mut self: Pin<&mut Self>,
+            cx: &mut task::Context<'_>,
+        ) -> Poll<Option<Result<(Self::PollItem, Self::PollBody), crate::common::Never>>> {
+            let mut this = self.as_mut();
+            debug_assert!(!this.rx_closed);
+            match this.rx.poll_recv(cx) {
+                Poll::Ready(Some((req, mut cb))) => {
+                    // check that future hasn't been canceled already
+                    match cb.poll_canceled(cx) {
+                        Poll::Ready(()) => {
+                            trace!("request canceled");
+                            Poll::Ready(None)
+                        }
+                        Poll::Pending => {
+                            let (parts, body) = req.into_parts();
+                            let head = RequestHead {
+                                version: parts.version,
+                                subject: crate::proto::RequestLine(parts.method, parts.uri),
+                                headers: parts.headers,
+                                extensions: parts.extensions,
+                            };
+                            this.callback = Some(cb);
+                            Poll::Ready(Some(Ok((head, body))))
+                        }
+                    }
+                }
+                Poll::Ready(None) => {
+                    // user has dropped sender handle
+                    trace!("client tx closed");
+                    this.rx_closed = true;
+                    Poll::Ready(None)
+                }
+                Poll::Pending => Poll::Pending,
+            }
+        }
+
+        fn recv_msg(&mut self, msg: crate::Result<(Self::RecvItem, Body)>) -> crate::Result<()> {
+            match msg {
+                Ok((msg, body)) => {
+                    if let Some(cb) = self.callback.take() {
+                        let res = msg.into_response(body);
+                        cb.send(Ok(res));
+                        Ok(())
+                    } else {
+                        // Getting here is likely a bug! An error should have happened
+                        // in Conn::require_empty_read() before ever parsing a
+                        // full message!
+                        Err(crate::Error::new_unexpected_message())
+                    }
+                }
+                Err(err) => {
+                    if let Some(cb) = self.callback.take() {
+                        cb.send(Err((err, None)));
+                        Ok(())
+                    } else if !self.rx_closed {
+                        self.rx.close();
+                        if let Some((req, cb)) = self.rx.try_recv() {
+                            trace!("canceling queued request with connection error: {}", err);
+                            // in this case, the message was never even started, so it's safe to tell
+                            // the user that the request was completely canceled
+                            cb.send(Err((crate::Error::new_canceled().with(err), Some(req))));
+                            Ok(())
+                        } else {
+                            Err(err)
+                        }
+                    } else {
+                        Err(err)
+                    }
+                }
+            }
+        }
+
+        fn poll_ready(&mut self, cx: &mut task::Context<'_>) -> Poll<Result<(), ()>> {
+            match self.callback {
+                Some(ref mut cb) => match cb.poll_canceled(cx) {
+                    Poll::Ready(()) => {
+                        trace!("callback receiver has dropped");
+                        Poll::Ready(Err(()))
+                    }
+                    Poll::Pending => Poll::Ready(Ok(())),
+                },
+                None => Poll::Ready(Err(())),
+            }
+        }
+
+        fn should_poll(&self) -> bool {
+            self.callback.is_none()
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::proto::h1::ClientTransaction;
+    use std::time::Duration;
+
+    #[test]
+    fn client_read_bytes_before_writing_request() {
+        let _ = pretty_env_logger::try_init();
+
+        tokio_test::task::spawn(()).enter(|cx, _| {
+            let (io, mut handle) = tokio_test::io::Builder::new().build_with_handle();
+
+            // Block at 0 for now, but we will release this response before
+            // the request is ready to write later...
+            let (mut tx, rx) = crate::client::dispatch::channel();
+            let conn = Conn::<_, bytes::Bytes, ClientTransaction>::new(io);
+            let mut dispatcher = Dispatcher::new(Client::new(rx), conn);
+
+            // First poll is needed to allow tx to send...
+            assert!(Pin::new(&mut dispatcher).poll(cx).is_pending());
+
+            // Unblock our IO, which has a response before we've sent request!
+            //
+            handle.read(b"HTTP/1.1 200 OK\r\n\r\n");
+
+            let mut res_rx = tx
+                .try_send(crate::Request::new(crate::Body::empty()))
+                .unwrap();
+
+            tokio_test::assert_ready_ok!(Pin::new(&mut dispatcher).poll(cx));
+            let err = tokio_test::assert_ready_ok!(Pin::new(&mut res_rx).poll(cx))
+                .expect_err("callback should send error");
+
+            match (err.0.kind(), err.1) {
+                (&crate::error::Kind::Canceled, Some(_)) => (),
+                other => panic!("expected Canceled, got {:?}", other),
+            }
+        });
+    }
+
+    #[tokio::test]
+    async fn client_flushing_is_not_ready_for_next_request() {
+        let _ = pretty_env_logger::try_init();
+
+        let (io, _handle) = tokio_test::io::Builder::new()
+            .write(b"POST / HTTP/1.1\r\ncontent-length: 4\r\n\r\n")
+            .read(b"HTTP/1.1 200 OK\r\ncontent-length: 0\r\n\r\n")
+            .wait(std::time::Duration::from_secs(2))
+            .build_with_handle();
+
+        let (mut tx, rx) = crate::client::dispatch::channel();
+        let mut conn = Conn::<_, bytes::Bytes, ClientTransaction>::new(io);
+        conn.set_write_strategy_queue();
+
+        let dispatcher = Dispatcher::new(Client::new(rx), conn);
+        let _dispatcher = tokio::spawn(async move { dispatcher.await });
+
+        let req = crate::Request::builder()
+            .method("POST")
+            .body(crate::Body::from("reee"))
+            .unwrap();
+
+        let res = tx.try_send(req).unwrap().await.expect("response");
+        drop(res);
+
+        assert!(!tx.is_ready());
+    }
+
+    #[tokio::test]
+    async fn body_empty_chunks_ignored() {
+        let _ = pretty_env_logger::try_init();
+
+        let io = tokio_test::io::Builder::new()
+            // no reading or writing, just be blocked for the test...
+            .wait(Duration::from_secs(5))
+            .build();
+
+        let (mut tx, rx) = crate::client::dispatch::channel();
+        let conn = Conn::<_, bytes::Bytes, ClientTransaction>::new(io);
+        let mut dispatcher = tokio_test::task::spawn(Dispatcher::new(Client::new(rx), conn));
+
+        // First poll is needed to allow tx to send...
+        assert!(dispatcher.poll().is_pending());
+
+        let body = {
+            let (mut tx, body) = crate::Body::channel();
+            tx.try_send_data("".into()).unwrap();
+            body
+        };
+
+        let _res_rx = tx.try_send(crate::Request::new(body)).unwrap();
+
+        // Ensure conn.write_body wasn't called with the empty chunk.
+        // If it is, it will trigger an assertion.
+        assert!(dispatcher.poll().is_pending());
+    }
+}

hyper/src/proto/h1/encode.rs

@@ -0,0 +1,439 @@
+use std::fmt;
+use std::io::IoSlice;
+
+use bytes::buf::{Chain, Take};
+use bytes::Buf;
+use tracing::trace;
+
+use super::io::WriteBuf;
+
+type StaticBuf = &'static [u8];
+
+/// Encoders to handle different Transfer-Encodings.
+#[derive(Debug, Clone, PartialEq)]
+pub(crate) struct Encoder {
+    kind: Kind,
+    is_last: bool,
+}
+
+#[derive(Debug)]
+pub(crate) struct EncodedBuf<B> {
+    kind: BufKind<B>,
+}
+
+#[derive(Debug)]
+pub(crate) struct NotEof(u64);
+
+#[derive(Debug, PartialEq, Clone)]
+enum Kind {
+    /// An Encoder for when Transfer-Encoding includes `chunked`.
+    Chunked,
+    /// An Encoder for when Content-Length is set.
+    ///
+    /// Enforces that the body is not longer than the Content-Length header.
+    Length(u64),
+    /// An Encoder for when neither Content-Length nor Chunked encoding is set.
+    ///
+    /// This is mostly only used with HTTP/1.0 with a length. This kind requires
+    /// the connection to be closed when the body is finished.
+    #[cfg(feature = "server")]
+    CloseDelimited,
+}
+
+#[derive(Debug)]
+enum BufKind<B> {
+    Exact(B),
+    Limited(Take<B>),
+    Chunked(Chain<Chain<ChunkSize, B>, StaticBuf>),
+    ChunkedEnd(StaticBuf),
+}
+
+impl Encoder {
+    fn new(kind: Kind) -> Encoder {
+        Encoder {
+            kind,
+            is_last: false,
+        }
+    }
+    pub(crate) fn chunked() -> Encoder {
+        Encoder::new(Kind::Chunked)
+    }
+
+    pub(crate) fn length(len: u64) -> Encoder {
+        Encoder::new(Kind::Length(len))
+    }
+
+    #[cfg(feature = "server")]
+    pub(crate) fn close_delimited() -> Encoder {
+        Encoder::new(Kind::CloseDelimited)
+    }
+
+    pub(crate) fn is_eof(&self) -> bool {
+        matches!(self.kind, Kind::Length(0))
+    }
+
+    #[cfg(feature = "server")]
+    pub(crate) fn set_last(mut self, is_last: bool) -> Self {
+        self.is_last = is_last;
+        self
+    }
+
+    pub(crate) fn is_last(&self) -> bool {
+        self.is_last
+    }
+
+    pub(crate) fn is_close_delimited(&self) -> bool {
+        match self.kind {
+            #[cfg(feature = "server")]
+            Kind::CloseDelimited => true,
+            _ => false,
+        }
+    }
+
+    pub(crate) fn end<B>(&self) -> Result<Option<EncodedBuf<B>>, NotEof> {
+        match self.kind {
+            Kind::Length(0) => Ok(None),
+            Kind::Chunked => Ok(Some(EncodedBuf {
+                kind: BufKind::ChunkedEnd(b"0\r\n\r\n"),
+            })),
+            #[cfg(feature = "server")]
+            Kind::CloseDelimited => Ok(None),
+            Kind::Length(n) => Err(NotEof(n)),
+        }
+    }
+
+    pub(crate) fn encode<B>(&mut self, msg: B) -> EncodedBuf<B>
+    where
+        B: Buf,
+    {
+        let len = msg.remaining();
+        debug_assert!(len > 0, "encode() called with empty buf");
+
+        let kind = match self.kind {
+            Kind::Chunked => {
+                trace!("encoding chunked {}B", len);
+                let buf = ChunkSize::new(len)
+                    .chain(msg)
+                    .chain(b"\r\n" as &'static [u8]);
+                BufKind::Chunked(buf)
+            }
+            Kind::Length(ref mut remaining) => {
+                trace!("sized write, len = {}", len);
+                if len as u64 > *remaining {
+                    let limit = *remaining as usize;
+                    *remaining = 0;
+                    BufKind::Limited(msg.take(limit))
+                } else {
+                    *remaining -= len as u64;
+                    BufKind::Exact(msg)
+                }
+            }
+            #[cfg(feature = "server")]
+            Kind::CloseDelimited => {
+                trace!("close delimited write {}B", len);
+                BufKind::Exact(msg)
+            }
+        };
+        EncodedBuf { kind }
+    }
+
+    pub(super) fn encode_and_end<B>(&self, msg: B, dst: &mut WriteBuf<EncodedBuf<B>>) -> bool
+    where
+        B: Buf,
+    {
+        let len = msg.remaining();
+        debug_assert!(len > 0, "encode() called with empty buf");
+
+        match self.kind {
+            Kind::Chunked => {
+                trace!("encoding chunked {}B", len);
+                let buf = ChunkSize::new(len)
+                    .chain(msg)
+                    .chain(b"\r\n0\r\n\r\n" as &'static [u8]);
+                dst.buffer(buf);
+                !self.is_last
+            }
+            Kind::Length(remaining) => {
+                use std::cmp::Ordering;
+
+                trace!("sized write, len = {}", len);
+                match (len as u64).cmp(&remaining) {
+                    Ordering::Equal => {
+                        dst.buffer(msg);
+                        !self.is_last
+                    }
+                    Ordering::Greater => {
+                        dst.buffer(msg.take(remaining as usize));
+                        !self.is_last
+                    }
+                    Ordering::Less => {
+                        dst.buffer(msg);
+                        false
+                    }
+                }
+            }
+            #[cfg(feature = "server")]
+            Kind::CloseDelimited => {
+                trace!("close delimited write {}B", len);
+                dst.buffer(msg);
+                false
+            }
+        }
+    }
+
+    /// Encodes the full body, without verifying the remaining length matches.
+    ///
+    /// This is used in conjunction with HttpBody::__hyper_full_data(), which
+    /// means we can trust that the buf has the correct size (the buf itself
+    /// was checked to make the headers).
+    pub(super) fn danger_full_buf<B>(self, msg: B, dst: &mut WriteBuf<EncodedBuf<B>>)
+    where
+        B: Buf,
+    {
+        debug_assert!(msg.remaining() > 0, "encode() called with empty buf");
+        debug_assert!(
+            match self.kind {
+                Kind::Length(len) => len == msg.remaining() as u64,
+                _ => true,
+            },
+            "danger_full_buf length mismatches"
+        );
+
+        match self.kind {
+            Kind::Chunked => {
+                let len = msg.remaining();
+                trace!("encoding chunked {}B", len);
+                let buf = ChunkSize::new(len)
+                    .chain(msg)
+                    .chain(b"\r\n0\r\n\r\n" as &'static [u8]);
+                dst.buffer(buf);
+            }
+            _ => {
+                dst.buffer(msg);
+            }
+        }
+    }
+}
+
+impl<B> Buf for EncodedBuf<B>
+where
+    B: Buf,
+{
+    #[inline]
+    fn remaining(&self) -> usize {
+        match self.kind {
+            BufKind::Exact(ref b) => b.remaining(),
+            BufKind::Limited(ref b) => b.remaining(),
+            BufKind::Chunked(ref b) => b.remaining(),
+            BufKind::ChunkedEnd(ref b) => b.remaining(),
+        }
+    }
+
+    #[inline]
+    fn chunk(&self) -> &[u8] {
+        match self.kind {
+            BufKind::Exact(ref b) => b.chunk(),
+            BufKind::Limited(ref b) => b.chunk(),
+            BufKind::Chunked(ref b) => b.chunk(),
+            BufKind::ChunkedEnd(ref b) => b.chunk(),
+        }
+    }
+
+    #[inline]
+    fn advance(&mut self, cnt: usize) {
+        match self.kind {
+            BufKind::Exact(ref mut b) => b.advance(cnt),
+            BufKind::Limited(ref mut b) => b.advance(cnt),
+            BufKind::Chunked(ref mut b) => b.advance(cnt),
+            BufKind::ChunkedEnd(ref mut b) => b.advance(cnt),
+        }
+    }
+
+    #[inline]
+    fn chunks_vectored<'t>(&'t self, dst: &mut [IoSlice<'t>]) -> usize {
+        match self.kind {
+            BufKind::Exact(ref b) => b.chunks_vectored(dst),
+            BufKind::Limited(ref b) => b.chunks_vectored(dst),
+            BufKind::Chunked(ref b) => b.chunks_vectored(dst),
+            BufKind::ChunkedEnd(ref b) => b.chunks_vectored(dst),
+        }
+    }
+}
+
+#[cfg(target_pointer_width = "32")]
+const USIZE_BYTES: usize = 4;
+
+#[cfg(target_pointer_width = "64")]
+const USIZE_BYTES: usize = 8;
+
+// each byte will become 2 hex
+const CHUNK_SIZE_MAX_BYTES: usize = USIZE_BYTES * 2;
+
+#[derive(Clone, Copy)]
+struct ChunkSize {
+    bytes: [u8; CHUNK_SIZE_MAX_BYTES + 2],
+    pos: u8,
+    len: u8,
+}
+
+impl ChunkSize {
+    fn new(len: usize) -> ChunkSize {
+        use std::fmt::Write;
+        let mut size = ChunkSize {
+            bytes: [0; CHUNK_SIZE_MAX_BYTES + 2],
+            pos: 0,
+            len: 0,
+        };
+        write!(&mut size, "{:X}\r\n", len).expect("CHUNK_SIZE_MAX_BYTES should fit any usize");
+        size
+    }
+}
+
+impl Buf for ChunkSize {
+    #[inline]
+    fn remaining(&self) -> usize {
+        (self.len - self.pos).into()
+    }
+
+    #[inline]
+    fn chunk(&self) -> &[u8] {
+        &self.bytes[self.pos.into()..self.len.into()]
+    }
+
+    #[inline]
+    fn advance(&mut self, cnt: usize) {
+        assert!(cnt <= self.remaining());
+        self.pos += cnt as u8; // just asserted cnt fits in u8
+    }
+}
+
+impl fmt::Debug for ChunkSize {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("ChunkSize")
+            .field("bytes", &&self.bytes[..self.len.into()])
+            .field("pos", &self.pos)
+            .finish()
+    }
+}
+
+impl fmt::Write for ChunkSize {
+    fn write_str(&mut self, num: &str) -> fmt::Result {
+        use std::io::Write;
+        (&mut self.bytes[self.len.into()..])
+            .write_all(num.as_bytes())
+            .expect("&mut [u8].write() cannot error");
+        self.len += num.len() as u8; // safe because bytes is never bigger than 256
+        Ok(())
+    }
+}
+
+impl<B: Buf> From<B> for EncodedBuf<B> {
+    fn from(buf: B) -> Self {
+        EncodedBuf {
+            kind: BufKind::Exact(buf),
+        }
+    }
+}
+
+impl<B: Buf> From<Take<B>> for EncodedBuf<B> {
+    fn from(buf: Take<B>) -> Self {
+        EncodedBuf {
+            kind: BufKind::Limited(buf),
+        }
+    }
+}
+
+impl<B: Buf> From<Chain<Chain<ChunkSize, B>, StaticBuf>> for EncodedBuf<B> {
+    fn from(buf: Chain<Chain<ChunkSize, B>, StaticBuf>) -> Self {
+        EncodedBuf {
+            kind: BufKind::Chunked(buf),
+        }
+    }
+}
+
+impl fmt::Display for NotEof {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "early end, expected {} more bytes", self.0)
+    }
+}
+
+impl std::error::Error for NotEof {}
+
+#[cfg(test)]
+mod tests {
+    use bytes::BufMut;
+
+    use super::super::io::Cursor;
+    use super::Encoder;
+
+    #[test]
+    fn chunked() {
+        let mut encoder = Encoder::chunked();
+        let mut dst = Vec::new();
+
+        let msg1 = b"foo bar".as_ref();
+        let buf1 = encoder.encode(msg1);
+        dst.put(buf1);
+        assert_eq!(dst, b"7\r\nfoo bar\r\n");
+
+        let msg2 = b"baz quux herp".as_ref();
+        let buf2 = encoder.encode(msg2);
+        dst.put(buf2);
+
+        assert_eq!(dst, b"7\r\nfoo bar\r\nD\r\nbaz quux herp\r\n");
+
+        let end = encoder.end::<Cursor<Vec<u8>>>().unwrap().unwrap();
+        dst.put(end);
+
+        assert_eq!(
+            dst,
+            b"7\r\nfoo bar\r\nD\r\nbaz quux herp\r\n0\r\n\r\n".as_ref()
+        );
+    }
+
+    #[test]
+    fn length() {
+        let max_len = 8;
+        let mut encoder = Encoder::length(max_len as u64);
+        let mut dst = Vec::new();
+
+        let msg1 = b"foo bar".as_ref();
+        let buf1 = encoder.encode(msg1);
+        dst.put(buf1);
+
+        assert_eq!(dst, b"foo bar");
+        assert!(!encoder.is_eof());
+        encoder.end::<()>().unwrap_err();
+
+        let msg2 = b"baz".as_ref();
+        let buf2 = encoder.encode(msg2);
+        dst.put(buf2);
+
+        assert_eq!(dst.len(), max_len);
+        assert_eq!(dst, b"foo barb");
+        assert!(encoder.is_eof());
+        assert!(encoder.end::<()>().unwrap().is_none());
+    }
+
+    #[test]
+    fn eof() {
+        let mut encoder = Encoder::close_delimited();
+        let mut dst = Vec::new();
+
+        let msg1 = b"foo bar".as_ref();
+        let buf1 = encoder.encode(msg1);
+        dst.put(buf1);
+
+        assert_eq!(dst, b"foo bar");
+        assert!(!encoder.is_eof());
+        encoder.end::<()>().unwrap();
+
+        let msg2 = b"baz".as_ref();
+        let buf2 = encoder.encode(msg2);
+        dst.put(buf2);
+
+        assert_eq!(dst, b"foo barbaz");
+        assert!(!encoder.is_eof());
+        encoder.end::<()>().unwrap();
+    }
+}

hyper/src/proto/h1/mod.rs

@@ -0,0 +1,122 @@
+#[cfg(all(feature = "server", feature = "runtime"))]
+use std::{pin::Pin, time::Duration};
+
+use bytes::BytesMut;
+use http::{HeaderMap, Method};
+use httparse::ParserConfig;
+#[cfg(all(feature = "server", feature = "runtime"))]
+use tokio::time::Sleep;
+
+use crate::body::DecodedLength;
+use crate::proto::{BodyLength, MessageHead};
+
+pub(crate) use self::conn::Conn;
+pub(crate) use self::decode::Decoder;
+pub(crate) use self::dispatch::Dispatcher;
+pub(crate) use self::encode::{EncodedBuf, Encoder};
+//TODO: move out of h1::io
+pub(crate) use self::io::MINIMUM_MAX_BUFFER_SIZE;
+
+mod conn;
+mod decode;
+pub(crate) mod dispatch;
+mod encode;
+mod io;
+mod role;
+
+cfg_client! {
+    pub(crate) type ClientTransaction = role::Client;
+}
+
+cfg_server! {
+    pub(crate) type ServerTransaction = role::Server;
+}
+
+pub(crate) trait Http1Transaction {
+    type Incoming;
+    type Outgoing: Default;
+    const LOG: &'static str;
+    fn parse(bytes: &mut BytesMut, ctx: ParseContext<'_>) -> ParseResult<Self::Incoming>;
+    fn encode(enc: Encode<'_, Self::Outgoing>, dst: &mut Vec<u8>) -> crate::Result<Encoder>;
+
+    fn on_error(err: &crate::Error) -> Option<MessageHead<Self::Outgoing>>;
+
+    fn is_client() -> bool {
+        !Self::is_server()
+    }
+
+    fn is_server() -> bool {
+        !Self::is_client()
+    }
+
+    fn should_error_on_parse_eof() -> bool {
+        Self::is_client()
+    }
+
+    fn should_read_first() -> bool {
+        Self::is_server()
+    }
+
+    fn update_date() {}
+}
+
+/// Result newtype for Http1Transaction::parse.
+pub(crate) type ParseResult<T> = Result<Option<ParsedMessage<T>>, crate::error::Parse>;
+
+#[derive(Debug)]
+pub(crate) struct ParsedMessage<T> {
+    head: MessageHead<T>,
+    decode: DecodedLength,
+    expect_continue: bool,
+    keep_alive: bool,
+    wants_upgrade: bool,
+}
+
+pub(crate) struct ParseContext<'a> {
+    cached_headers: &'a mut Option<HeaderMap>,
+    req_method: &'a mut Option<Method>,
+    h1_parser_config: ParserConfig,
+    #[cfg(all(feature = "server", feature = "runtime"))]
+    h1_header_read_timeout: Option<Duration>,
+    #[cfg(all(feature = "server", feature = "runtime"))]
+    h1_header_read_timeout_fut: &'a mut Option<Pin<Box<Sleep>>>,
+    #[cfg(all(feature = "server", feature = "runtime"))]
+    h1_header_read_timeout_running: &'a mut bool,
+    preserve_header_case: bool,
+    #[cfg(feature = "ffi")]
+    preserve_header_order: bool,
+    h09_responses: bool,
+    #[cfg(feature = "ffi")]
+    on_informational: &'a mut Option<crate::ffi::OnInformational>,
+    #[cfg(feature = "ffi")]
+    raw_headers: bool,
+}
+
+/// Passed to Http1Transaction::encode
+pub(crate) struct Encode<'a, T> {
+    head: &'a mut MessageHead<T>,
+    body: Option<BodyLength>,
+    #[cfg(feature = "server")]
+    keep_alive: bool,
+    req_method: &'a mut Option<Method>,
+    title_case_headers: bool,
+}
+
+/// Extra flags that a request "wants", like expect-continue or upgrades.
+#[derive(Clone, Copy, Debug)]
+struct Wants(u8);
+
+impl Wants {
+    const EMPTY: Wants = Wants(0b00);
+    const EXPECT: Wants = Wants(0b01);
+    const UPGRADE: Wants = Wants(0b10);
+
+    #[must_use]
+    fn add(self, other: Wants) -> Wants {
+        Wants(self.0 | other.0)
+    }
+
+    fn contains(&self, other: Wants) -> bool {
+        (self.0 & other.0) == other.0
+    }
+}

hyper/src/proto/h2/client.rs

@@ -0,0 +1,450 @@
+use std::error::Error as StdError;
+#[cfg(feature = "runtime")]
+use std::time::Duration;
+
+use bytes::Bytes;
+use futures_channel::{mpsc, oneshot};
+use futures_util::future::{self, Either, FutureExt as _, TryFutureExt as _};
+use futures_util::stream::StreamExt as _;
+use h2::client::{Builder, SendRequest};
+use h2::SendStream;
+use http::{Method, StatusCode};
+use tokio::io::{AsyncRead, AsyncWrite};
+use tracing::{debug, trace, warn};
+
+use super::{ping, H2Upgraded, PipeToSendStream, SendBuf};
+use crate::body::HttpBody;
+use crate::client::dispatch::Callback;
+use crate::common::{exec::Exec, task, Future, Never, Pin, Poll};
+use crate::ext::Protocol;
+use crate::headers;
+use crate::proto::h2::UpgradedSendStream;
+use crate::proto::Dispatched;
+use crate::upgrade::Upgraded;
+use crate::{Body, Request, Response};
+use h2::client::ResponseFuture;
+
+type ClientRx<B> = crate::client::dispatch::Receiver<Request<B>, Response<Body>>;
+
+///// An mpsc channel is used to help notify the `Connection` task when *all*
+///// other handles to it have been dropped, so that it can shutdown.
+type ConnDropRef = mpsc::Sender<Never>;
+
+///// A oneshot channel watches the `Connection` task, and when it completes,
+///// the "dispatch" task will be notified and can shutdown sooner.
+type ConnEof = oneshot::Receiver<Never>;
+
+// Our defaults are chosen for the "majority" case, which usually are not
+// resource constrained, and so the spec default of 64kb can be too limiting
+// for performance.
+const DEFAULT_CONN_WINDOW: u32 = 1024 * 1024 * 5; // 5mb
+const DEFAULT_STREAM_WINDOW: u32 = 1024 * 1024 * 2; // 2mb
+const DEFAULT_MAX_FRAME_SIZE: u32 = 1024 * 16; // 16kb
+const DEFAULT_MAX_SEND_BUF_SIZE: usize = 1024 * 1024; // 1mb
+
+#[derive(Clone, Debug)]
+pub(crate) struct Config {
+    pub(crate) adaptive_window: bool,
+    pub(crate) initial_conn_window_size: u32,
+    pub(crate) initial_stream_window_size: u32,
+    pub(crate) max_frame_size: u32,
+    #[cfg(feature = "runtime")]
+    pub(crate) keep_alive_interval: Option<Duration>,
+    #[cfg(feature = "runtime")]
+    pub(crate) keep_alive_timeout: Duration,
+    #[cfg(feature = "runtime")]
+    pub(crate) keep_alive_while_idle: bool,
+    pub(crate) max_concurrent_reset_streams: Option<usize>,
+    pub(crate) max_send_buffer_size: usize,
+}
+
+impl Default for Config {
+    fn default() -> Config {
+        Config {
+            adaptive_window: false,
+            initial_conn_window_size: DEFAULT_CONN_WINDOW,
+            initial_stream_window_size: DEFAULT_STREAM_WINDOW,
+            max_frame_size: DEFAULT_MAX_FRAME_SIZE,
+            #[cfg(feature = "runtime")]
+            keep_alive_interval: None,
+            #[cfg(feature = "runtime")]
+            keep_alive_timeout: Duration::from_secs(20),
+            #[cfg(feature = "runtime")]
+            keep_alive_while_idle: false,
+            max_concurrent_reset_streams: None,
+            max_send_buffer_size: DEFAULT_MAX_SEND_BUF_SIZE,
+        }
+    }
+}
+
+fn new_builder(config: &Config) -> Builder {
+    let mut builder = Builder::default();
+    builder
+        .initial_window_size(config.initial_stream_window_size)
+        .initial_connection_window_size(config.initial_conn_window_size)
+        .max_frame_size(config.max_frame_size)
+        .max_send_buffer_size(config.max_send_buffer_size)
+        .enable_push(false);
+    if let Some(max) = config.max_concurrent_reset_streams {
+        builder.max_concurrent_reset_streams(max);
+    }
+    builder
+}
+
+fn new_ping_config(config: &Config) -> ping::Config {
+    ping::Config {
+        bdp_initial_window: if config.adaptive_window {
+            Some(config.initial_stream_window_size)
+        } else {
+            None
+        },
+        #[cfg(feature = "runtime")]
+        keep_alive_interval: config.keep_alive_interval,
+        #[cfg(feature = "runtime")]
+        keep_alive_timeout: config.keep_alive_timeout,
+        #[cfg(feature = "runtime")]
+        keep_alive_while_idle: config.keep_alive_while_idle,
+    }
+}
+
+pub(crate) async fn handshake<T, B>(
+    io: T,
+    req_rx: ClientRx<B>,
+    config: &Config,
+    exec: Exec,
+) -> crate::Result<ClientTask<B>>
+where
+    T: AsyncRead + AsyncWrite + Send + Unpin + 'static,
+    B: HttpBody,
+    B::Data: Send + 'static,
+{
+    let (h2_tx, mut conn) = new_builder(config)
+        .handshake::<_, SendBuf<B::Data>>(io)
+        .await
+        .map_err(crate::Error::new_h2)?;
+
+    // An mpsc channel is used entirely to detect when the
+    // 'Client' has been dropped. This is to get around a bug
+    // in h2 where dropping all SendRequests won't notify a
+    // parked Connection.
+    let (conn_drop_ref, rx) = mpsc::channel(1);
+    let (cancel_tx, conn_eof) = oneshot::channel();
+
+    let conn_drop_rx = rx.into_future().map(|(item, _rx)| {
+        if let Some(never) = item {
+            match never {}
+        }
+    });
+
+    let ping_config = new_ping_config(&config);
+
+    let (conn, ping) = if ping_config.is_enabled() {
+        let pp = conn.ping_pong().expect("conn.ping_pong");
+        let (recorder, mut ponger) = ping::channel(pp, ping_config);
+
+        let conn = future::poll_fn(move |cx| {
+            match ponger.poll(cx) {
+                Poll::Ready(ping::Ponged::SizeUpdate(wnd)) => {
+                    conn.set_target_window_size(wnd);
+                    conn.set_initial_window_size(wnd)?;
+                }
+                #[cfg(feature = "runtime")]
+                Poll::Ready(ping::Ponged::KeepAliveTimedOut) => {
+                    debug!("connection keep-alive timed out");
+                    return Poll::Ready(Ok(()));
+                }
+                Poll::Pending => {}
+            }
+
+            Pin::new(&mut conn).poll(cx)
+        });
+        (Either::Left(conn), recorder)
+    } else {
+        (Either::Right(conn), ping::disabled())
+    };
+    let conn = conn.map_err(|e| debug!("connection error: {}", e));
+
+    exec.execute(conn_task(conn, conn_drop_rx, cancel_tx));
+
+    Ok(ClientTask {
+        ping,
+        conn_drop_ref,
+        conn_eof,
+        executor: exec,
+        h2_tx,
+        req_rx,
+        fut_ctx: None,
+    })
+}
+
+async fn conn_task<C, D>(conn: C, drop_rx: D, cancel_tx: oneshot::Sender<Never>)
+where
+    C: Future + Unpin,
+    D: Future<Output = ()> + Unpin,
+{
+    match future::select(conn, drop_rx).await {
+        Either::Left(_) => {
+            // ok or err, the `conn` has finished
+        }
+        Either::Right(((), conn)) => {
+            // mpsc has been dropped, hopefully polling
+            // the connection some more should start shutdown
+            // and then close
+            trace!("send_request dropped, starting conn shutdown");
+            drop(cancel_tx);
+            let _ = conn.await;
+        }
+    }
+}
+
+struct FutCtx<B>
+where
+    B: HttpBody,
+{
+    is_connect: bool,
+    eos: bool,
+    fut: ResponseFuture,
+    body_tx: SendStream<SendBuf<B::Data>>,
+    body: B,
+    cb: Callback<Request<B>, Response<Body>>,
+}
+
+impl<B: HttpBody> Unpin for FutCtx<B> {}
+
+pub(crate) struct ClientTask<B>
+where
+    B: HttpBody,
+{
+    ping: ping::Recorder,
+    conn_drop_ref: ConnDropRef,
+    conn_eof: ConnEof,
+    executor: Exec,
+    h2_tx: SendRequest<SendBuf<B::Data>>,
+    req_rx: ClientRx<B>,
+    fut_ctx: Option<FutCtx<B>>,
+}
+
+impl<B> ClientTask<B>
+where
+    B: HttpBody + 'static,
+{
+    pub(crate) fn is_extended_connect_protocol_enabled(&self) -> bool {
+        self.h2_tx.is_extended_connect_protocol_enabled()
+    }
+}
+
+impl<B> ClientTask<B>
+where
+    B: HttpBody + Send + 'static,
+    B::Data: Send,
+    B::Error: Into<Box<dyn StdError + Send + Sync>>,
+{
+    fn poll_pipe(&mut self, f: FutCtx<B>, cx: &mut task::Context<'_>) {
+        let ping = self.ping.clone();
+        let send_stream = if !f.is_connect {
+            if !f.eos {
+                let mut pipe = Box::pin(PipeToSendStream::new(f.body, f.body_tx)).map(|res| {
+                    if let Err(e) = res {
+                        debug!("client request body error: {}", e);
+                    }
+                });
+
+                // eagerly see if the body pipe is ready and
+                // can thus skip allocating in the executor
+                match Pin::new(&mut pipe).poll(cx) {
+                    Poll::Ready(_) => (),
+                    Poll::Pending => {
+                        let conn_drop_ref = self.conn_drop_ref.clone();
+                        // keep the ping recorder's knowledge of an
+                        // "open stream" alive while this body is
+                        // still sending...
+                        let ping = ping.clone();
+                        let pipe = pipe.map(move |x| {
+                            drop(conn_drop_ref);
+                            drop(ping);
+                            x
+                        });
+                        // Clear send task
+                        self.executor.execute(pipe);
+                    }
+                }
+            }
+
+            None
+        } else {
+            Some(f.body_tx)
+        };
+
+        let fut = f.fut.map(move |result| match result {
+            Ok(res) => {
+                // record that we got the response headers
+                ping.record_non_data();
+
+                let content_length = headers::content_length_parse_all(res.headers());
+                if let (Some(mut send_stream), StatusCode::OK) = (send_stream, res.status()) {
+                    if content_length.map_or(false, |len| len != 0) {
+                        warn!("h2 connect response with non-zero body not supported");
+
+                        send_stream.send_reset(h2::Reason::INTERNAL_ERROR);
+                        return Err((
+                            crate::Error::new_h2(h2::Reason::INTERNAL_ERROR.into()),
+                            None,
+                        ));
+                    }
+                    let (parts, recv_stream) = res.into_parts();
+                    let mut res = Response::from_parts(parts, Body::empty());
+
+                    let (pending, on_upgrade) = crate::upgrade::pending();
+                    let io = H2Upgraded {
+                        ping,
+                        send_stream: unsafe { UpgradedSendStream::new(send_stream) },
+                        recv_stream,
+                        buf: Bytes::new(),
+                    };
+                    let upgraded = Upgraded::new(io, Bytes::new());
+
+                    pending.fulfill(upgraded);
+                    res.extensions_mut().insert(on_upgrade);
+
+                    Ok(res)
+                } else {
+                    let res = res.map(|stream| {
+                        let ping = ping.for_stream(&stream);
+                        crate::Body::h2(stream, content_length.into(), ping)
+                    });
+                    Ok(res)
+                }
+            }
+            Err(err) => {
+                ping.ensure_not_timed_out().map_err(|e| (e, None))?;
+
+                debug!("client response error: {}", err);
+                Err((crate::Error::new_h2(err), None))
+            }
+        });
+        self.executor.execute(f.cb.send_when(fut));
+    }
+}
+
+impl<B> Future for ClientTask<B>
+where
+    B: HttpBody + Send + 'static,
+    B::Data: Send,
+    B::Error: Into<Box<dyn StdError + Send + Sync>>,
+{
+    type Output = crate::Result<Dispatched>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Self::Output> {
+        loop {
+            match ready!(self.h2_tx.poll_ready(cx)) {
+                Ok(()) => (),
+                Err(err) => {
+                    self.ping.ensure_not_timed_out()?;
+                    return if err.reason() == Some(::h2::Reason::NO_ERROR) {
+                        trace!("connection gracefully shutdown");
+                        Poll::Ready(Ok(Dispatched::Shutdown))
+                    } else {
+                        Poll::Ready(Err(crate::Error::new_h2(err)))
+                    };
+                }
+            };
+
+            match self.fut_ctx.take() {
+                // If we were waiting on pending open
+                // continue where we left off.
+                Some(f) => {
+                    self.poll_pipe(f, cx);
+                    continue;
+                }
+                None => (),
+            }
+
+            match self.req_rx.poll_recv(cx) {
+                Poll::Ready(Some((req, cb))) => {
+                    // check that future hasn't been canceled already
+                    if cb.is_canceled() {
+                        trace!("request callback is canceled");
+                        continue;
+                    }
+                    let (head, body) = req.into_parts();
+                    let mut req = ::http::Request::from_parts(head, ());
+                    super::strip_connection_headers(req.headers_mut(), true);
+                    if let Some(len) = body.size_hint().exact() {
+                        if len != 0 || headers::method_has_defined_payload_semantics(req.method()) {
+                            headers::set_content_length_if_missing(req.headers_mut(), len);
+                        }
+                    }
+
+                    let is_connect = req.method() == Method::CONNECT;
+                    let eos = body.is_end_stream();
+
+                    if is_connect {
+                        if headers::content_length_parse_all(req.headers())
+                            .map_or(false, |len| len != 0)
+                        {
+                            warn!("h2 connect request with non-zero body not supported");
+                            cb.send(Err((
+                                crate::Error::new_h2(h2::Reason::INTERNAL_ERROR.into()),
+                                None,
+                            )));
+                            continue;
+                        }
+                    }
+
+                    if let Some(protocol) = req.extensions_mut().remove::<Protocol>() {
+                        req.extensions_mut().insert(protocol.into_inner());
+                    }
+
+                    let (fut, body_tx) = match self.h2_tx.send_request(req, !is_connect && eos) {
+                        Ok(ok) => ok,
+                        Err(err) => {
+                            debug!("client send request error: {}", err);
+                            cb.send(Err((crate::Error::new_h2(err), None)));
+                            continue;
+                        }
+                    };
+
+                    let f = FutCtx {
+                        is_connect,
+                        eos,
+                        fut,
+                        body_tx,
+                        body,
+                        cb,
+                    };
+
+                    // Check poll_ready() again.
+                    // If the call to send_request() resulted in the new stream being pending open
+                    // we have to wait for the open to complete before accepting new requests.
+                    match self.h2_tx.poll_ready(cx) {
+                        Poll::Pending => {
+                            // Save Context
+                            self.fut_ctx = Some(f);
+                            return Poll::Pending;
+                        }
+                        Poll::Ready(Ok(())) => (),
+                        Poll::Ready(Err(err)) => {
+                            f.cb.send(Err((crate::Error::new_h2(err), None)));
+                            continue;
+                        }
+                    }
+                    self.poll_pipe(f, cx);
+                    continue;
+                }
+
+                Poll::Ready(None) => {
+                    trace!("client::dispatch::Sender dropped");
+                    return Poll::Ready(Ok(Dispatched::Shutdown));
+                }
+
+                Poll::Pending => match ready!(Pin::new(&mut self.conn_eof).poll(cx)) {
+                    Ok(never) => match never {},
+                    Err(_conn_is_eof) => {
+                        trace!("connection task is closed, closing dispatch task");
+                        return Poll::Ready(Ok(Dispatched::Shutdown));
+                    }
+                },
+            }
+        }
+    }
+}

hyper/src/proto/h2/mod.rs

@@ -0,0 +1,471 @@
+use bytes::{Buf, Bytes};
+use h2::{Reason, RecvStream, SendStream};
+use http::header::{HeaderName, CONNECTION, TE, TRAILER, TRANSFER_ENCODING, UPGRADE};
+use http::HeaderMap;
+use pin_project_lite::pin_project;
+use std::error::Error as StdError;
+use std::io::{self, Cursor, IoSlice};
+use std::mem;
+use std::task::Context;
+use tokio::io::{AsyncRead, AsyncWrite, ReadBuf};
+use tracing::{debug, trace, warn};
+
+use crate::body::HttpBody;
+use crate::common::{task, Future, Pin, Poll};
+use crate::proto::h2::ping::Recorder;
+
+pub(crate) mod ping;
+
+cfg_client! {
+    pub(crate) mod client;
+    pub(crate) use self::client::ClientTask;
+}
+
+cfg_server! {
+    pub(crate) mod server;
+    pub(crate) use self::server::Server;
+}
+
+/// Default initial stream window size defined in HTTP2 spec.
+pub(crate) const SPEC_WINDOW_SIZE: u32 = 65_535;
+
+fn strip_connection_headers(headers: &mut HeaderMap, is_request: bool) {
+    // List of connection headers from:
+    // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Connection
+    //
+    // TE headers are allowed in HTTP/2 requests as long as the value is "trailers", so they're
+    // tested separately.
+    let connection_headers = [
+        HeaderName::from_lowercase(b"keep-alive").unwrap(),
+        HeaderName::from_lowercase(b"proxy-connection").unwrap(),
+        TRAILER,
+        TRANSFER_ENCODING,
+        UPGRADE,
+    ];
+
+    for header in connection_headers.iter() {
+        if headers.remove(header).is_some() {
+            warn!("Connection header illegal in HTTP/2: {}", header.as_str());
+        }
+    }
+
+    if is_request {
+        if headers
+            .get(TE)
+            .map(|te_header| te_header != "trailers")
+            .unwrap_or(false)
+        {
+            warn!("TE headers not set to \"trailers\" are illegal in HTTP/2 requests");
+            headers.remove(TE);
+        }
+    } else if headers.remove(TE).is_some() {
+        warn!("TE headers illegal in HTTP/2 responses");
+    }
+
+    if let Some(header) = headers.remove(CONNECTION) {
+        warn!(
+            "Connection header illegal in HTTP/2: {}",
+            CONNECTION.as_str()
+        );
+        let header_contents = header.to_str().unwrap();
+
+        // A `Connection` header may have a comma-separated list of names of other headers that
+        // are meant for only this specific connection.
+        //
+        // Iterate these names and remove them as headers. Connection-specific headers are
+        // forbidden in HTTP2, as that information has been moved into frame types of the h2
+        // protocol.
+        for name in header_contents.split(',') {
+            let name = name.trim();
+            headers.remove(name);
+        }
+    }
+}
+
+// body adapters used by both Client and Server
+
+pin_project! {
+    struct PipeToSendStream<S>
+    where
+        S: HttpBody,
+    {
+        body_tx: SendStream<SendBuf<S::Data>>,
+        data_done: bool,
+        #[pin]
+        stream: S,
+    }
+}
+
+impl<S> PipeToSendStream<S>
+where
+    S: HttpBody,
+{
+    fn new(stream: S, tx: SendStream<SendBuf<S::Data>>) -> PipeToSendStream<S> {
+        PipeToSendStream {
+            body_tx: tx,
+            data_done: false,
+            stream,
+        }
+    }
+}
+
+impl<S> Future for PipeToSendStream<S>
+where
+    S: HttpBody,
+    S::Error: Into<Box<dyn StdError + Send + Sync>>,
+{
+    type Output = crate::Result<()>;
+
+    fn poll(self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Self::Output> {
+        let mut me = self.project();
+        loop {
+            if !*me.data_done {
+                // we don't have the next chunk of data yet, so just reserve 1 byte to make
+                // sure there's some capacity available. h2 will handle the capacity management
+                // for the actual body chunk.
+                me.body_tx.reserve_capacity(1);
+
+                if me.body_tx.capacity() == 0 {
+                    loop {
+                        match ready!(me.body_tx.poll_capacity(cx)) {
+                            Some(Ok(0)) => {}
+                            Some(Ok(_)) => break,
+                            Some(Err(e)) => {
+                                return Poll::Ready(Err(crate::Error::new_body_write(e)))
+                            }
+                            None => {
+                                // None means the stream is no longer in a
+                                // streaming state, we either finished it
+                                // somehow, or the remote reset us.
+                                return Poll::Ready(Err(crate::Error::new_body_write(
+                                    "send stream capacity unexpectedly closed",
+                                )));
+                            }
+                        }
+                    }
+                } else if let Poll::Ready(reason) = me
+                    .body_tx
+                    .poll_reset(cx)
+                    .map_err(crate::Error::new_body_write)?
+                {
+                    debug!("stream received RST_STREAM: {:?}", reason);
+                    return Poll::Ready(Err(crate::Error::new_body_write(::h2::Error::from(
+                        reason,
+                    ))));
+                }
+
+                match ready!(me.stream.as_mut().poll_data(cx)) {
+                    Some(Ok(chunk)) => {
+                        let is_eos = me.stream.is_end_stream();
+                        trace!(
+                            "send body chunk: {} bytes, eos={}",
+                            chunk.remaining(),
+                            is_eos,
+                        );
+
+                        let buf = SendBuf::Buf(chunk);
+                        me.body_tx
+                            .send_data(buf, is_eos)
+                            .map_err(crate::Error::new_body_write)?;
+
+                        if is_eos {
+                            return Poll::Ready(Ok(()));
+                        }
+                    }
+                    Some(Err(e)) => return Poll::Ready(Err(me.body_tx.on_user_err(e))),
+                    None => {
+                        me.body_tx.reserve_capacity(0);
+                        let is_eos = me.stream.is_end_stream();
+                        if is_eos {
+                            return Poll::Ready(me.body_tx.send_eos_frame());
+                        } else {
+                            *me.data_done = true;
+                            // loop again to poll_trailers
+                        }
+                    }
+                }
+            } else {
+                if let Poll::Ready(reason) = me
+                    .body_tx
+                    .poll_reset(cx)
+                    .map_err(crate::Error::new_body_write)?
+                {
+                    debug!("stream received RST_STREAM: {:?}", reason);
+                    return Poll::Ready(Err(crate::Error::new_body_write(::h2::Error::from(
+                        reason,
+                    ))));
+                }
+
+                match ready!(me.stream.poll_trailers(cx)) {
+                    Ok(Some(trailers)) => {
+                        me.body_tx
+                            .send_trailers(trailers)
+                            .map_err(crate::Error::new_body_write)?;
+                        return Poll::Ready(Ok(()));
+                    }
+                    Ok(None) => {
+                        // There were no trailers, so send an empty DATA frame...
+                        return Poll::Ready(me.body_tx.send_eos_frame());
+                    }
+                    Err(e) => return Poll::Ready(Err(me.body_tx.on_user_err(e))),
+                }
+            }
+        }
+    }
+}
+
+trait SendStreamExt {
+    fn on_user_err<E>(&mut self, err: E) -> crate::Error
+    where
+        E: Into<Box<dyn std::error::Error + Send + Sync>>;
+    fn send_eos_frame(&mut self) -> crate::Result<()>;
+}
+
+impl<B: Buf> SendStreamExt for SendStream<SendBuf<B>> {
+    fn on_user_err<E>(&mut self, err: E) -> crate::Error
+    where
+        E: Into<Box<dyn std::error::Error + Send + Sync>>,
+    {
+        let err = crate::Error::new_user_body(err);
+        debug!("send body user stream error: {}", err);
+        self.send_reset(err.h2_reason());
+        err
+    }
+
+    fn send_eos_frame(&mut self) -> crate::Result<()> {
+        trace!("send body eos");
+        self.send_data(SendBuf::None, true)
+            .map_err(crate::Error::new_body_write)
+    }
+}
+
+#[repr(usize)]
+enum SendBuf<B> {
+    Buf(B),
+    Cursor(Cursor<Box<[u8]>>),
+    None,
+}
+
+impl<B: Buf> Buf for SendBuf<B> {
+    #[inline]
+    fn remaining(&self) -> usize {
+        match *self {
+            Self::Buf(ref b) => b.remaining(),
+            Self::Cursor(ref c) => Buf::remaining(c),
+            Self::None => 0,
+        }
+    }
+
+    #[inline]
+    fn chunk(&self) -> &[u8] {
+        match *self {
+            Self::Buf(ref b) => b.chunk(),
+            Self::Cursor(ref c) => c.chunk(),
+            Self::None => &[],
+        }
+    }
+
+    #[inline]
+    fn advance(&mut self, cnt: usize) {
+        match *self {
+            Self::Buf(ref mut b) => b.advance(cnt),
+            Self::Cursor(ref mut c) => c.advance(cnt),
+            Self::None => {}
+        }
+    }
+
+    fn chunks_vectored<'a>(&'a self, dst: &mut [IoSlice<'a>]) -> usize {
+        match *self {
+            Self::Buf(ref b) => b.chunks_vectored(dst),
+            Self::Cursor(ref c) => c.chunks_vectored(dst),
+            Self::None => 0,
+        }
+    }
+}
+
+struct H2Upgraded<B>
+where
+    B: Buf,
+{
+    ping: Recorder,
+    send_stream: UpgradedSendStream<B>,
+    recv_stream: RecvStream,
+    buf: Bytes,
+}
+
+impl<B> AsyncRead for H2Upgraded<B>
+where
+    B: Buf,
+{
+    fn poll_read(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        read_buf: &mut ReadBuf<'_>,
+    ) -> Poll<Result<(), io::Error>> {
+        if self.buf.is_empty() {
+            self.buf = loop {
+                match ready!(self.recv_stream.poll_data(cx)) {
+                    None => return Poll::Ready(Ok(())),
+                    Some(Ok(buf)) if buf.is_empty() && !self.recv_stream.is_end_stream() => {
+                        continue
+                    }
+                    Some(Ok(buf)) => {
+                        self.ping.record_data(buf.len());
+                        break buf;
+                    }
+                    Some(Err(e)) => {
+                        return Poll::Ready(match e.reason() {
+                            Some(Reason::NO_ERROR) | Some(Reason::CANCEL) => Ok(()),
+                            Some(Reason::STREAM_CLOSED) => {
+                                Err(io::Error::new(io::ErrorKind::BrokenPipe, e))
+                            }
+                            _ => Err(h2_to_io_error(e)),
+                        })
+                    }
+                }
+            };
+        }
+        let cnt = std::cmp::min(self.buf.len(), read_buf.remaining());
+        read_buf.put_slice(&self.buf[..cnt]);
+        self.buf.advance(cnt);
+        let _ = self.recv_stream.flow_control().release_capacity(cnt);
+        Poll::Ready(Ok(()))
+    }
+}
+
+impl<B> AsyncWrite for H2Upgraded<B>
+where
+    B: Buf,
+{
+    fn poll_write(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+        buf: &[u8],
+    ) -> Poll<Result<usize, io::Error>> {
+        if buf.is_empty() {
+            return Poll::Ready(Ok(0));
+        }
+        self.send_stream.reserve_capacity(buf.len());
+
+        // We ignore all errors returned by `poll_capacity` and `write`, as we
+        // will get the correct from `poll_reset` anyway.
+        let cnt = match ready!(self.send_stream.poll_capacity(cx)) {
+            None => Some(0),
+            Some(Ok(cnt)) => self
+                .send_stream
+                .write(&buf[..cnt], false)
+                .ok()
+                .map(|()| cnt),
+            Some(Err(_)) => None,
+        };
+
+        if let Some(cnt) = cnt {
+            return Poll::Ready(Ok(cnt));
+        }
+
+        Poll::Ready(Err(h2_to_io_error(
+            match ready!(self.send_stream.poll_reset(cx)) {
+                Ok(Reason::NO_ERROR) | Ok(Reason::CANCEL) | Ok(Reason::STREAM_CLOSED) => {
+                    return Poll::Ready(Err(io::ErrorKind::BrokenPipe.into()))
+                }
+                Ok(reason) => reason.into(),
+                Err(e) => e,
+            },
+        )))
+    }
+
+    fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Result<(), io::Error>> {
+        Poll::Ready(Ok(()))
+    }
+
+    fn poll_shutdown(
+        mut self: Pin<&mut Self>,
+        cx: &mut Context<'_>,
+    ) -> Poll<Result<(), io::Error>> {
+        if self.send_stream.write(&[], true).is_ok() {
+            return Poll::Ready(Ok(()))
+        }
+
+        Poll::Ready(Err(h2_to_io_error(
+            match ready!(self.send_stream.poll_reset(cx)) {
+                Ok(Reason::NO_ERROR) => {
+                    return Poll::Ready(Ok(()))
+                }
+                Ok(Reason::CANCEL) | Ok(Reason::STREAM_CLOSED) => {
+                    return Poll::Ready(Err(io::ErrorKind::BrokenPipe.into()))
+                }
+                Ok(reason) => reason.into(),
+                Err(e) => e,
+            },
+        )))
+    }
+}
+
+fn h2_to_io_error(e: h2::Error) -> io::Error {
+    if e.is_io() {
+        e.into_io().unwrap()
+    } else {
+        io::Error::new(io::ErrorKind::Other, e)
+    }
+}
+
+struct UpgradedSendStream<B>(SendStream<SendBuf<Neutered<B>>>);
+
+impl<B> UpgradedSendStream<B>
+where
+    B: Buf,
+{
+    unsafe fn new(inner: SendStream<SendBuf<B>>) -> Self {
+        assert_eq!(mem::size_of::<B>(), mem::size_of::<Neutered<B>>());
+        Self(mem::transmute(inner))
+    }
+
+    fn reserve_capacity(&mut self, cnt: usize) {
+        unsafe { self.as_inner_unchecked().reserve_capacity(cnt) }
+    }
+
+    fn poll_capacity(&mut self, cx: &mut Context<'_>) -> Poll<Option<Result<usize, h2::Error>>> {
+        unsafe { self.as_inner_unchecked().poll_capacity(cx) }
+    }
+
+    fn poll_reset(&mut self, cx: &mut Context<'_>) -> Poll<Result<h2::Reason, h2::Error>> {
+        unsafe { self.as_inner_unchecked().poll_reset(cx) }
+    }
+
+    fn write(&mut self, buf: &[u8], end_of_stream: bool) -> Result<(), io::Error> {
+        let send_buf = SendBuf::Cursor(Cursor::new(buf.into()));
+        unsafe {
+            self.as_inner_unchecked()
+                .send_data(send_buf, end_of_stream)
+                .map_err(h2_to_io_error)
+        }
+    }
+
+    unsafe fn as_inner_unchecked(&mut self) -> &mut SendStream<SendBuf<B>> {
+        &mut *(&mut self.0 as *mut _ as *mut _)
+    }
+}
+
+#[repr(transparent)]
+struct Neutered<B> {
+    _inner: B,
+    impossible: Impossible,
+}
+
+enum Impossible {}
+
+unsafe impl<B> Send for Neutered<B> {}
+
+impl<B> Buf for Neutered<B> {
+    fn remaining(&self) -> usize {
+        match self.impossible {}
+    }
+
+    fn chunk(&self) -> &[u8] {
+        match self.impossible {}
+    }
+
+    fn advance(&mut self, _cnt: usize) {
+        match self.impossible {}
+    }
+}

hyper/src/proto/h2/ping.rs

@@ -0,0 +1,555 @@
+/// HTTP2 Ping usage
+///
+/// hyper uses HTTP2 pings for two purposes:
+///
+/// 1. Adaptive flow control using BDP
+/// 2. Connection keep-alive
+///
+/// Both cases are optional.
+///
+/// # BDP Algorithm
+///
+/// 1. When receiving a DATA frame, if a BDP ping isn't outstanding:
+///   1a. Record current time.
+///   1b. Send a BDP ping.
+/// 2. Increment the number of received bytes.
+/// 3. When the BDP ping ack is received:
+///   3a. Record duration from sent time.
+///   3b. Merge RTT with a running average.
+///   3c. Calculate bdp as bytes/rtt.
+///   3d. If bdp is over 2/3 max, set new max to bdp and update windows.
+
+#[cfg(feature = "runtime")]
+use std::fmt;
+#[cfg(feature = "runtime")]
+use std::future::Future;
+#[cfg(feature = "runtime")]
+use std::pin::Pin;
+use std::sync::{Arc, Mutex};
+use std::task::{self, Poll};
+use std::time::Duration;
+#[cfg(not(feature = "runtime"))]
+use std::time::Instant;
+
+use h2::{Ping, PingPong};
+#[cfg(feature = "runtime")]
+use tokio::time::{Instant, Sleep};
+use tracing::{debug, trace};
+
+type WindowSize = u32;
+
+pub(super) fn disabled() -> Recorder {
+    Recorder { shared: None }
+}
+
+pub(super) fn channel(ping_pong: PingPong, config: Config) -> (Recorder, Ponger) {
+    debug_assert!(
+        config.is_enabled(),
+        "ping channel requires bdp or keep-alive config",
+    );
+
+    let bdp = config.bdp_initial_window.map(|wnd| Bdp {
+        bdp: wnd,
+        max_bandwidth: 0.0,
+        rtt: 0.0,
+        ping_delay: Duration::from_millis(100),
+        stable_count: 0,
+    });
+
+    let (bytes, next_bdp_at) = if bdp.is_some() {
+        (Some(0), Some(Instant::now()))
+    } else {
+        (None, None)
+    };
+
+    #[cfg(feature = "runtime")]
+    let keep_alive = config.keep_alive_interval.map(|interval| KeepAlive {
+        interval,
+        timeout: config.keep_alive_timeout,
+        while_idle: config.keep_alive_while_idle,
+        timer: Box::pin(tokio::time::sleep(interval)),
+        state: KeepAliveState::Init,
+    });
+
+    #[cfg(feature = "runtime")]
+    let last_read_at = keep_alive.as_ref().map(|_| Instant::now());
+
+    let shared = Arc::new(Mutex::new(Shared {
+        bytes,
+        #[cfg(feature = "runtime")]
+        last_read_at,
+        #[cfg(feature = "runtime")]
+        is_keep_alive_timed_out: false,
+        ping_pong,
+        ping_sent_at: None,
+        next_bdp_at,
+    }));
+
+    (
+        Recorder {
+            shared: Some(shared.clone()),
+        },
+        Ponger {
+            bdp,
+            #[cfg(feature = "runtime")]
+            keep_alive,
+            shared,
+        },
+    )
+}
+
+#[derive(Clone)]
+pub(super) struct Config {
+    pub(super) bdp_initial_window: Option<WindowSize>,
+    /// If no frames are received in this amount of time, a PING frame is sent.
+    #[cfg(feature = "runtime")]
+    pub(super) keep_alive_interval: Option<Duration>,
+    /// After sending a keepalive PING, the connection will be closed if
+    /// a pong is not received in this amount of time.
+    #[cfg(feature = "runtime")]
+    pub(super) keep_alive_timeout: Duration,
+    /// If true, sends pings even when there are no active streams.
+    #[cfg(feature = "runtime")]
+    pub(super) keep_alive_while_idle: bool,
+}
+
+#[derive(Clone)]
+pub(crate) struct Recorder {
+    shared: Option<Arc<Mutex<Shared>>>,
+}
+
+pub(super) struct Ponger {
+    bdp: Option<Bdp>,
+    #[cfg(feature = "runtime")]
+    keep_alive: Option<KeepAlive>,
+    shared: Arc<Mutex<Shared>>,
+}
+
+struct Shared {
+    ping_pong: PingPong,
+    ping_sent_at: Option<Instant>,
+
+    // bdp
+    /// If `Some`, bdp is enabled, and this tracks how many bytes have been
+    /// read during the current sample.
+    bytes: Option<usize>,
+    /// We delay a variable amount of time between BDP pings. This allows us
+    /// to send less pings as the bandwidth stabilizes.
+    next_bdp_at: Option<Instant>,
+
+    // keep-alive
+    /// If `Some`, keep-alive is enabled, and the Instant is how long ago
+    /// the connection read the last frame.
+    #[cfg(feature = "runtime")]
+    last_read_at: Option<Instant>,
+
+    #[cfg(feature = "runtime")]
+    is_keep_alive_timed_out: bool,
+}
+
+struct Bdp {
+    /// Current BDP in bytes
+    bdp: u32,
+    /// Largest bandwidth we've seen so far.
+    max_bandwidth: f64,
+    /// Round trip time in seconds
+    rtt: f64,
+    /// Delay the next ping by this amount.
+    ///
+    /// This will change depending on how stable the current bandwidth is.
+    ping_delay: Duration,
+    /// The count of ping round trips where BDP has stayed the same.
+    stable_count: u32,
+}
+
+#[cfg(feature = "runtime")]
+struct KeepAlive {
+    /// If no frames are received in this amount of time, a PING frame is sent.
+    interval: Duration,
+    /// After sending a keepalive PING, the connection will be closed if
+    /// a pong is not received in this amount of time.
+    timeout: Duration,
+    /// If true, sends pings even when there are no active streams.
+    while_idle: bool,
+
+    state: KeepAliveState,
+    timer: Pin<Box<Sleep>>,
+}
+
+#[cfg(feature = "runtime")]
+enum KeepAliveState {
+    Init,
+    Scheduled,
+    PingSent,
+}
+
+pub(super) enum Ponged {
+    SizeUpdate(WindowSize),
+    #[cfg(feature = "runtime")]
+    KeepAliveTimedOut,
+}
+
+#[cfg(feature = "runtime")]
+#[derive(Debug)]
+pub(super) struct KeepAliveTimedOut;
+
+// ===== impl Config =====
+
+impl Config {
+    pub(super) fn is_enabled(&self) -> bool {
+        #[cfg(feature = "runtime")]
+        {
+            self.bdp_initial_window.is_some() || self.keep_alive_interval.is_some()
+        }
+
+        #[cfg(not(feature = "runtime"))]
+        {
+            self.bdp_initial_window.is_some()
+        }
+    }
+}
+
+// ===== impl Recorder =====
+
+impl Recorder {
+    pub(crate) fn record_data(&self, len: usize) {
+        let shared = if let Some(ref shared) = self.shared {
+            shared
+        } else {
+            return;
+        };
+
+        let mut locked = shared.lock().unwrap();
+
+        #[cfg(feature = "runtime")]
+        locked.update_last_read_at();
+
+        // are we ready to send another bdp ping?
+        // if not, we don't need to record bytes either
+
+        if let Some(ref next_bdp_at) = locked.next_bdp_at {
+            if Instant::now() < *next_bdp_at {
+                return;
+            } else {
+                locked.next_bdp_at = None;
+            }
+        }
+
+        if let Some(ref mut bytes) = locked.bytes {
+            *bytes += len;
+        } else {
+            // no need to send bdp ping if bdp is disabled
+            return;
+        }
+
+        if !locked.is_ping_sent() {
+            locked.send_ping();
+        }
+    }
+
+    pub(crate) fn record_non_data(&self) {
+        #[cfg(feature = "runtime")]
+        {
+            let shared = if let Some(ref shared) = self.shared {
+                shared
+            } else {
+                return;
+            };
+
+            let mut locked = shared.lock().unwrap();
+
+            locked.update_last_read_at();
+        }
+    }
+
+    /// If the incoming stream is already closed, convert self into
+    /// a disabled reporter.
+    #[cfg(feature = "client")]
+    pub(super) fn for_stream(self, stream: &h2::RecvStream) -> Self {
+        if stream.is_end_stream() {
+            disabled()
+        } else {
+            self
+        }
+    }
+
+    pub(super) fn ensure_not_timed_out(&self) -> crate::Result<()> {
+        #[cfg(feature = "runtime")]
+        {
+            if let Some(ref shared) = self.shared {
+                let locked = shared.lock().unwrap();
+                if locked.is_keep_alive_timed_out {
+                    return Err(KeepAliveTimedOut.crate_error());
+                }
+            }
+        }
+
+        // else
+        Ok(())
+    }
+}
+
+// ===== impl Ponger =====
+
+impl Ponger {
+    pub(super) fn poll(&mut self, cx: &mut task::Context<'_>) -> Poll<Ponged> {
+        let now = Instant::now();
+        let mut locked = self.shared.lock().unwrap();
+        #[cfg(feature = "runtime")]
+        let is_idle = self.is_idle();
+
+        #[cfg(feature = "runtime")]
+        {
+            if let Some(ref mut ka) = self.keep_alive {
+                ka.schedule(is_idle, &locked);
+                ka.maybe_ping(cx, &mut locked);
+            }
+        }
+
+        if !locked.is_ping_sent() {
+            // XXX: this doesn't register a waker...?
+            return Poll::Pending;
+        }
+
+        match locked.ping_pong.poll_pong(cx) {
+            Poll::Ready(Ok(_pong)) => {
+                let start = locked
+                    .ping_sent_at
+                    .expect("pong received implies ping_sent_at");
+                locked.ping_sent_at = None;
+                let rtt = now - start;
+                trace!("recv pong");
+
+                #[cfg(feature = "runtime")]
+                {
+                    if let Some(ref mut ka) = self.keep_alive {
+                        locked.update_last_read_at();
+                        ka.schedule(is_idle, &locked);
+                    }
+                }
+
+                if let Some(ref mut bdp) =  self.bdp {
+                    let bytes = locked.bytes.expect("bdp enabled implies bytes");
+                    locked.bytes = Some(0); // reset
+                    trace!("received BDP ack; bytes = {}, rtt = {:?}", bytes, rtt);
+
+                    let update = bdp.calculate(bytes, rtt);
+                    locked.next_bdp_at = Some(now + bdp.ping_delay);
+                    if let Some(update) = update {
+                        return Poll::Ready(Ponged::SizeUpdate(update))
+                    }
+                }
+            }
+            Poll::Ready(Err(e)) => {
+                debug!("pong error: {}", e);
+            }
+            Poll::Pending => {
+                #[cfg(feature = "runtime")]
+                {
+                    if let Some(ref mut ka) = self.keep_alive {
+                        if let Err(KeepAliveTimedOut) = ka.maybe_timeout(cx) {
+                            self.keep_alive = None;
+                            locked.is_keep_alive_timed_out = true;
+                            return Poll::Ready(Ponged::KeepAliveTimedOut);
+                        }
+                    }
+                }
+            }
+        }
+
+        // XXX: this doesn't register a waker...?
+        Poll::Pending
+    }
+
+    #[cfg(feature = "runtime")]
+    fn is_idle(&self) -> bool {
+        Arc::strong_count(&self.shared) <= 2
+    }
+}
+
+// ===== impl Shared =====
+
+impl Shared {
+    fn send_ping(&mut self) {
+        match self.ping_pong.send_ping(Ping::opaque()) {
+            Ok(()) => {
+                self.ping_sent_at = Some(Instant::now());
+                trace!("sent ping");
+            }
+            Err(err) => {
+                debug!("error sending ping: {}", err);
+            }
+        }
+    }
+
+    fn is_ping_sent(&self) -> bool {
+        self.ping_sent_at.is_some()
+    }
+
+    #[cfg(feature = "runtime")]
+    fn update_last_read_at(&mut self) {
+        if self.last_read_at.is_some() {
+            self.last_read_at = Some(Instant::now());
+        }
+    }
+
+    #[cfg(feature = "runtime")]
+    fn last_read_at(&self) -> Instant {
+        self.last_read_at.expect("keep_alive expects last_read_at")
+    }
+}
+
+// ===== impl Bdp =====
+
+/// Any higher than this likely will be hitting the TCP flow control.
+const BDP_LIMIT: usize = 1024 * 1024 * 16;
+
+impl Bdp {
+    fn calculate(&mut self, bytes: usize, rtt: Duration) -> Option<WindowSize> {
+        // No need to do any math if we're at the limit.
+        if self.bdp as usize == BDP_LIMIT {
+            self.stabilize_delay();
+            return None;
+        }
+
+        // average the rtt
+        let rtt = seconds(rtt);
+        if self.rtt == 0.0 {
+            // First sample means rtt is first rtt.
+            self.rtt = rtt;
+        } else {
+            // Weigh this rtt as 1/8 for a moving average.
+            self.rtt += (rtt - self.rtt) * 0.125;
+        }
+
+        // calculate the current bandwidth
+        let bw = (bytes as f64) / (self.rtt * 1.5);
+        trace!("current bandwidth = {:.1}B/s", bw);
+
+        if bw < self.max_bandwidth {
+            // not a faster bandwidth, so don't update
+            self.stabilize_delay();
+            return None;
+        } else {
+            self.max_bandwidth = bw;
+        }
+
+        // if the current `bytes` sample is at least 2/3 the previous
+        // bdp, increase to double the current sample.
+        if bytes >= self.bdp as usize * 2 / 3 {
+            self.bdp = (bytes * 2).min(BDP_LIMIT) as WindowSize;
+            trace!("BDP increased to {}", self.bdp);
+
+            self.stable_count = 0;
+            self.ping_delay /= 2;
+            Some(self.bdp)
+        } else {
+            self.stabilize_delay();
+            None
+        }
+    }
+
+    fn stabilize_delay(&mut self) {
+        if self.ping_delay < Duration::from_secs(10) {
+            self.stable_count += 1;
+
+            if self.stable_count >= 2 {
+                self.ping_delay *= 4;
+                self.stable_count = 0;
+            }
+        }
+    }
+}
+
+fn seconds(dur: Duration) -> f64 {
+    const NANOS_PER_SEC: f64 = 1_000_000_000.0;
+    let secs = dur.as_secs() as f64;
+    secs + (dur.subsec_nanos() as f64) / NANOS_PER_SEC
+}
+
+// ===== impl KeepAlive =====
+
+#[cfg(feature = "runtime")]
+impl KeepAlive {
+    fn schedule(&mut self, is_idle: bool, shared: &Shared) {
+        match self.state {
+            KeepAliveState::Init => {
+                if !self.while_idle && is_idle {
+                    return;
+                }
+
+                self.state = KeepAliveState::Scheduled;
+                let interval = shared.last_read_at() + self.interval;
+                self.timer.as_mut().reset(interval);
+            }
+            KeepAliveState::PingSent => {
+                if shared.is_ping_sent() {
+                    return;
+                }
+
+                self.state = KeepAliveState::Scheduled;
+                let interval = shared.last_read_at() + self.interval;
+                self.timer.as_mut().reset(interval);
+            }
+            KeepAliveState::Scheduled => (),
+        }
+    }
+
+    fn maybe_ping(&mut self, cx: &mut task::Context<'_>, shared: &mut Shared) {
+        match self.state {
+            KeepAliveState::Scheduled => {
+                if Pin::new(&mut self.timer).poll(cx).is_pending() {
+                    return;
+                }
+                // check if we've received a frame while we were scheduled
+                if shared.last_read_at() + self.interval > self.timer.deadline() {
+                    self.state = KeepAliveState::Init;
+                    cx.waker().wake_by_ref(); // schedule us again
+                    return;
+                }
+                trace!("keep-alive interval ({:?}) reached", self.interval);
+                shared.send_ping();
+                self.state = KeepAliveState::PingSent;
+                let timeout = Instant::now() + self.timeout;
+                self.timer.as_mut().reset(timeout);
+            }
+            KeepAliveState::Init | KeepAliveState::PingSent => (),
+        }
+    }
+
+    fn maybe_timeout(&mut self, cx: &mut task::Context<'_>) -> Result<(), KeepAliveTimedOut> {
+        match self.state {
+            KeepAliveState::PingSent => {
+                if Pin::new(&mut self.timer).poll(cx).is_pending() {
+                    return Ok(());
+                }
+                trace!("keep-alive timeout ({:?}) reached", self.timeout);
+                Err(KeepAliveTimedOut)
+            }
+            KeepAliveState::Init | KeepAliveState::Scheduled => Ok(()),
+        }
+    }
+}
+
+// ===== impl KeepAliveTimedOut =====
+
+#[cfg(feature = "runtime")]
+impl KeepAliveTimedOut {
+    pub(super) fn crate_error(self) -> crate::Error {
+        crate::Error::new(crate::error::Kind::Http2).with(self)
+    }
+}
+
+#[cfg(feature = "runtime")]
+impl fmt::Display for KeepAliveTimedOut {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str("keep-alive timed out")
+    }
+}
+
+#[cfg(feature = "runtime")]
+impl std::error::Error for KeepAliveTimedOut {
+    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
+        Some(&crate::error::TimedOut)
+    }
+}

hyper/src/proto/h2/server.rs

@@ -0,0 +1,548 @@
+use std::error::Error as StdError;
+use std::marker::Unpin;
+#[cfg(feature = "runtime")]
+use std::time::Duration;
+
+use bytes::Bytes;
+use h2::server::{Connection, Handshake, SendResponse};
+use h2::{Reason, RecvStream};
+use http::{Method, Request};
+use pin_project_lite::pin_project;
+use tokio::io::{AsyncRead, AsyncWrite};
+use tracing::{debug, trace, warn};
+
+use super::{ping, PipeToSendStream, SendBuf};
+use crate::body::HttpBody;
+use crate::common::exec::ConnStreamExec;
+use crate::common::{date, task, Future, Pin, Poll};
+use crate::ext::Protocol;
+use crate::headers;
+use crate::proto::h2::ping::Recorder;
+use crate::proto::h2::{H2Upgraded, UpgradedSendStream};
+use crate::proto::Dispatched;
+use crate::service::HttpService;
+
+use crate::upgrade::{OnUpgrade, Pending, Upgraded};
+use crate::{Body, Response};
+
+// Our defaults are chosen for the "majority" case, which usually are not
+// resource constrained, and so the spec default of 64kb can be too limiting
+// for performance.
+//
+// At the same time, a server more often has multiple clients connected, and
+// so is more likely to use more resources than a client would.
+const DEFAULT_CONN_WINDOW: u32 = 1024 * 1024; // 1mb
+const DEFAULT_STREAM_WINDOW: u32 = 1024 * 1024; // 1mb
+const DEFAULT_MAX_FRAME_SIZE: u32 = 1024 * 16; // 16kb
+const DEFAULT_MAX_SEND_BUF_SIZE: usize = 1024 * 400; // 400kb
+// 16 MB "sane default" taken from golang http2
+const DEFAULT_SETTINGS_MAX_HEADER_LIST_SIZE: u32 = 16 << 20;
+
+#[derive(Clone, Debug)]
+pub(crate) struct Config {
+    pub(crate) adaptive_window: bool,
+    pub(crate) initial_conn_window_size: u32,
+    pub(crate) initial_stream_window_size: u32,
+    pub(crate) max_frame_size: u32,
+    pub(crate) enable_connect_protocol: bool,
+    pub(crate) max_concurrent_streams: Option<u32>,
+    #[cfg(feature = "runtime")]
+    pub(crate) keep_alive_interval: Option<Duration>,
+    #[cfg(feature = "runtime")]
+    pub(crate) keep_alive_timeout: Duration,
+    pub(crate) max_send_buffer_size: usize,
+    pub(crate) max_header_list_size: u32,
+}
+
+impl Default for Config {
+    fn default() -> Config {
+        Config {
+            adaptive_window: false,
+            initial_conn_window_size: DEFAULT_CONN_WINDOW,
+            initial_stream_window_size: DEFAULT_STREAM_WINDOW,
+            max_frame_size: DEFAULT_MAX_FRAME_SIZE,
+            enable_connect_protocol: false,
+            max_concurrent_streams: None,
+            #[cfg(feature = "runtime")]
+            keep_alive_interval: None,
+            #[cfg(feature = "runtime")]
+            keep_alive_timeout: Duration::from_secs(20),
+            max_send_buffer_size: DEFAULT_MAX_SEND_BUF_SIZE,
+            max_header_list_size: DEFAULT_SETTINGS_MAX_HEADER_LIST_SIZE,
+        }
+    }
+}
+
+pin_project! {
+    pub(crate) struct Server<T, S, B, E>
+    where
+        S: HttpService<Body>,
+        B: HttpBody,
+    {
+        exec: E,
+        service: S,
+        state: State<T, B>,
+    }
+}
+
+enum State<T, B>
+where
+    B: HttpBody,
+{
+    Handshaking {
+        ping_config: ping::Config,
+        hs: Handshake<T, SendBuf<B::Data>>,
+    },
+    Serving(Serving<T, B>),
+    Closed,
+}
+
+struct Serving<T, B>
+where
+    B: HttpBody,
+{
+    ping: Option<(ping::Recorder, ping::Ponger)>,
+    conn: Connection<T, SendBuf<B::Data>>,
+    closing: Option<crate::Error>,
+}
+
+impl<T, S, B, E> Server<T, S, B, E>
+where
+    T: AsyncRead + AsyncWrite + Unpin,
+    S: HttpService<Body, ResBody = B>,
+    S::Error: Into<Box<dyn StdError + Send + Sync>>,
+    B: HttpBody + 'static,
+    E: ConnStreamExec<S::Future, B>,
+{
+    pub(crate) fn new(io: T, service: S, config: &Config, exec: E) -> Server<T, S, B, E> {
+        let mut builder = h2::server::Builder::default();
+        builder
+            .initial_window_size(config.initial_stream_window_size)
+            .initial_connection_window_size(config.initial_conn_window_size)
+            .max_frame_size(config.max_frame_size)
+            .max_header_list_size(config.max_header_list_size)
+            .max_send_buffer_size(config.max_send_buffer_size);
+        if let Some(max) = config.max_concurrent_streams {
+            builder.max_concurrent_streams(max);
+        }
+        if config.enable_connect_protocol {
+            builder.enable_connect_protocol();
+        }
+        let handshake = builder.handshake(io);
+
+        let bdp = if config.adaptive_window {
+            Some(config.initial_stream_window_size)
+        } else {
+            None
+        };
+
+        let ping_config = ping::Config {
+            bdp_initial_window: bdp,
+            #[cfg(feature = "runtime")]
+            keep_alive_interval: config.keep_alive_interval,
+            #[cfg(feature = "runtime")]
+            keep_alive_timeout: config.keep_alive_timeout,
+            // If keep-alive is enabled for servers, always enabled while
+            // idle, so it can more aggressively close dead connections.
+            #[cfg(feature = "runtime")]
+            keep_alive_while_idle: true,
+        };
+
+        Server {
+            exec,
+            state: State::Handshaking {
+                ping_config,
+                hs: handshake,
+            },
+            service,
+        }
+    }
+
+    pub(crate) fn graceful_shutdown(&mut self) {
+        trace!("graceful_shutdown");
+        match self.state {
+            State::Handshaking { .. } => {
+                // fall-through, to replace state with Closed
+            }
+            State::Serving(ref mut srv) => {
+                if srv.closing.is_none() {
+                    srv.conn.graceful_shutdown();
+                }
+                return;
+            }
+            State::Closed => {
+                return;
+            }
+        }
+        self.state = State::Closed;
+    }
+}
+
+impl<T, S, B, E> Future for Server<T, S, B, E>
+where
+    T: AsyncRead + AsyncWrite + Unpin,
+    S: HttpService<Body, ResBody = B>,
+    S::Error: Into<Box<dyn StdError + Send + Sync>>,
+    B: HttpBody + 'static,
+    E: ConnStreamExec<S::Future, B>,
+{
+    type Output = crate::Result<Dispatched>;
+
+    fn poll(mut self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Self::Output> {
+        let me = &mut *self;
+        loop {
+            let next = match me.state {
+                State::Handshaking {
+                    ref mut hs,
+                    ref ping_config,
+                } => {
+                    let mut conn = ready!(Pin::new(hs).poll(cx).map_err(crate::Error::new_h2))?;
+                    let ping = if ping_config.is_enabled() {
+                        let pp = conn.ping_pong().expect("conn.ping_pong");
+                        Some(ping::channel(pp, ping_config.clone()))
+                    } else {
+                        None
+                    };
+                    State::Serving(Serving {
+                        ping,
+                        conn,
+                        closing: None,
+                    })
+                }
+                State::Serving(ref mut srv) => {
+                    ready!(srv.poll_server(cx, &mut me.service, &mut me.exec))?;
+                    return Poll::Ready(Ok(Dispatched::Shutdown));
+                }
+                State::Closed => {
+                    // graceful_shutdown was called before handshaking finished,
+                    // nothing to do here...
+                    return Poll::Ready(Ok(Dispatched::Shutdown));
+                }
+            };
+            me.state = next;
+        }
+    }
+}
+
+impl<T, B> Serving<T, B>
+where
+    T: AsyncRead + AsyncWrite + Unpin,
+    B: HttpBody + 'static,
+{
+    fn poll_server<S, E>(
+        &mut self,
+        cx: &mut task::Context<'_>,
+        service: &mut S,
+        exec: &mut E,
+    ) -> Poll<crate::Result<()>>
+    where
+        S: HttpService<Body, ResBody = B>,
+        S::Error: Into<Box<dyn StdError + Send + Sync>>,
+        E: ConnStreamExec<S::Future, B>,
+    {
+        if self.closing.is_none() {
+            loop {
+                self.poll_ping(cx);
+
+                // Check that the service is ready to accept a new request.
+                //
+                // - If not, just drive the connection some.
+                // - If ready, try to accept a new request from the connection.
+                match service.poll_ready(cx) {
+                    Poll::Ready(Ok(())) => (),
+                    Poll::Pending => {
+                        // use `poll_closed` instead of `poll_accept`,
+                        // in order to avoid accepting a request.
+                        ready!(self.conn.poll_closed(cx).map_err(crate::Error::new_h2))?;
+                        trace!("incoming connection complete");
+                        return Poll::Ready(Ok(()));
+                    }
+                    Poll::Ready(Err(err)) => {
+                        let err = crate::Error::new_user_service(err);
+                        debug!("service closed: {}", err);
+
+                        let reason = err.h2_reason();
+                        if reason == Reason::NO_ERROR {
+                            // NO_ERROR is only used for graceful shutdowns...
+                            trace!("interpreting NO_ERROR user error as graceful_shutdown");
+                            self.conn.graceful_shutdown();
+                        } else {
+                            trace!("abruptly shutting down with {:?}", reason);
+                            self.conn.abrupt_shutdown(reason);
+                        }
+                        self.closing = Some(err);
+                        break;
+                    }
+                }
+
+                // When the service is ready, accepts an incoming request.
+                match ready!(self.conn.poll_accept(cx)) {
+                    Some(Ok((req, mut respond))) => {
+                        trace!("incoming request");
+                        let content_length = headers::content_length_parse_all(req.headers());
+                        let ping = self
+                            .ping
+                            .as_ref()
+                            .map(|ping| ping.0.clone())
+                            .unwrap_or_else(ping::disabled);
+
+                        // Record the headers received
+                        ping.record_non_data();
+
+                        let is_connect = req.method() == Method::CONNECT;
+                        let (mut parts, stream) = req.into_parts();
+                        let (mut req, connect_parts) = if !is_connect {
+                            (
+                                Request::from_parts(
+                                    parts,
+                                    crate::Body::h2(stream, content_length.into(), ping),
+                                ),
+                                None,
+                            )
+                        } else {
+                            if content_length.map_or(false, |len| len != 0) {
+                                warn!("h2 connect request with non-zero body not supported");
+                                respond.send_reset(h2::Reason::INTERNAL_ERROR);
+                                return Poll::Ready(Ok(()));
+                            }
+                            let (pending, upgrade) = crate::upgrade::pending();
+                            debug_assert!(parts.extensions.get::<OnUpgrade>().is_none());
+                            parts.extensions.insert(upgrade);
+                            (
+                                Request::from_parts(parts, crate::Body::empty()),
+                                Some(ConnectParts {
+                                    pending,
+                                    ping,
+                                    recv_stream: stream,
+                                }),
+                            )
+                        };
+
+                        if let Some(protocol) = req.extensions_mut().remove::<h2::ext::Protocol>() {
+                            req.extensions_mut().insert(Protocol::from_inner(protocol));
+                        }
+
+                        let fut = H2Stream::new(service.call(req), connect_parts, respond);
+                        exec.execute_h2stream(fut);
+                    }
+                    Some(Err(e)) => {
+                        return Poll::Ready(Err(crate::Error::new_h2(e)));
+                    }
+                    None => {
+                        // no more incoming streams...
+                        if let Some((ref ping, _)) = self.ping {
+                            ping.ensure_not_timed_out()?;
+                        }
+
+                        trace!("incoming connection complete");
+                        return Poll::Ready(Ok(()));
+                    }
+                }
+            }
+        }
+
+        debug_assert!(
+            self.closing.is_some(),
+            "poll_server broke loop without closing"
+        );
+
+        ready!(self.conn.poll_closed(cx).map_err(crate::Error::new_h2))?;
+
+        Poll::Ready(Err(self.closing.take().expect("polled after error")))
+    }
+
+    fn poll_ping(&mut self, cx: &mut task::Context<'_>) {
+        if let Some((_, ref mut estimator)) = self.ping {
+            match estimator.poll(cx) {
+                Poll::Ready(ping::Ponged::SizeUpdate(wnd)) => {
+                    self.conn.set_target_window_size(wnd);
+                    let _ = self.conn.set_initial_window_size(wnd);
+                }
+                #[cfg(feature = "runtime")]
+                Poll::Ready(ping::Ponged::KeepAliveTimedOut) => {
+                    debug!("keep-alive timed out, closing connection");
+                    self.conn.abrupt_shutdown(h2::Reason::NO_ERROR);
+                }
+                Poll::Pending => {}
+            }
+        }
+    }
+}
+
+pin_project! {
+    #[allow(missing_debug_implementations)]
+    pub struct H2Stream<F, B>
+    where
+        B: HttpBody,
+    {
+        reply: SendResponse<SendBuf<B::Data>>,
+        #[pin]
+        state: H2StreamState<F, B>,
+    }
+}
+
+pin_project! {
+    #[project = H2StreamStateProj]
+    enum H2StreamState<F, B>
+    where
+        B: HttpBody,
+    {
+        Service {
+            #[pin]
+            fut: F,
+            connect_parts: Option<ConnectParts>,
+        },
+        Body {
+            #[pin]
+            pipe: PipeToSendStream<B>,
+        },
+    }
+}
+
+struct ConnectParts {
+    pending: Pending,
+    ping: Recorder,
+    recv_stream: RecvStream,
+}
+
+impl<F, B> H2Stream<F, B>
+where
+    B: HttpBody,
+{
+    fn new(
+        fut: F,
+        connect_parts: Option<ConnectParts>,
+        respond: SendResponse<SendBuf<B::Data>>,
+    ) -> H2Stream<F, B> {
+        H2Stream {
+            reply: respond,
+            state: H2StreamState::Service { fut, connect_parts },
+        }
+    }
+}
+
+macro_rules! reply {
+    ($me:expr, $res:expr, $eos:expr) => {{
+        match $me.reply.send_response($res, $eos) {
+            Ok(tx) => tx,
+            Err(e) => {
+                debug!("send response error: {}", e);
+                $me.reply.send_reset(Reason::INTERNAL_ERROR);
+                return Poll::Ready(Err(crate::Error::new_h2(e)));
+            }
+        }
+    }};
+}
+
+impl<F, B, E> H2Stream<F, B>
+where
+    F: Future<Output = Result<Response<B>, E>>,
+    B: HttpBody,
+    B::Data: 'static,
+    B::Error: Into<Box<dyn StdError + Send + Sync>>,
+    E: Into<Box<dyn StdError + Send + Sync>>,
+{
+    fn poll2(self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<crate::Result<()>> {
+        let mut me = self.project();
+        loop {
+            let next = match me.state.as_mut().project() {
+                H2StreamStateProj::Service {
+                    fut: h,
+                    connect_parts,
+                } => {
+                    let res = match h.poll(cx) {
+                        Poll::Ready(Ok(r)) => r,
+                        Poll::Pending => {
+                            // Response is not yet ready, so we want to check if the client has sent a
+                            // RST_STREAM frame which would cancel the current request.
+                            if let Poll::Ready(reason) =
+                                me.reply.poll_reset(cx).map_err(crate::Error::new_h2)?
+                            {
+                                debug!("stream received RST_STREAM: {:?}", reason);
+                                return Poll::Ready(Err(crate::Error::new_h2(reason.into())));
+                            }
+                            return Poll::Pending;
+                        }
+                        Poll::Ready(Err(e)) => {
+                            let err = crate::Error::new_user_service(e);
+                            warn!("http2 service errored: {}", err);
+                            me.reply.send_reset(err.h2_reason());
+                            return Poll::Ready(Err(err));
+                        }
+                    };
+
+                    let (head, body) = res.into_parts();
+                    let mut res = ::http::Response::from_parts(head, ());
+                    super::strip_connection_headers(res.headers_mut(), false);
+
+                    // set Date header if it isn't already set...
+                    res.headers_mut()
+                        .entry(::http::header::DATE)
+                        .or_insert_with(date::update_and_header_value);
+
+                    if let Some(connect_parts) = connect_parts.take() {
+                        if res.status().is_success() {
+                            if headers::content_length_parse_all(res.headers())
+                                .map_or(false, |len| len != 0)
+                            {
+                                warn!("h2 successful response to CONNECT request with body not supported");
+                                me.reply.send_reset(h2::Reason::INTERNAL_ERROR);
+                                return Poll::Ready(Err(crate::Error::new_user_header()));
+                            }
+                            let send_stream = reply!(me, res, false);
+                            connect_parts.pending.fulfill(Upgraded::new(
+                                H2Upgraded {
+                                    ping: connect_parts.ping,
+                                    recv_stream: connect_parts.recv_stream,
+                                    send_stream: unsafe { UpgradedSendStream::new(send_stream) },
+                                    buf: Bytes::new(),
+                                },
+                                Bytes::new(),
+                            ));
+                            return Poll::Ready(Ok(()));
+                        }
+                    }
+
+
+                    if !body.is_end_stream() {
+                        // automatically set Content-Length from body...
+                        if let Some(len) = body.size_hint().exact() {
+                            headers::set_content_length_if_missing(res.headers_mut(), len);
+                        }
+
+                        let body_tx = reply!(me, res, false);
+                        H2StreamState::Body {
+                            pipe: PipeToSendStream::new(body, body_tx),
+                        }
+                    } else {
+                        reply!(me, res, true);
+                        return Poll::Ready(Ok(()));
+                    }
+                }
+                H2StreamStateProj::Body { pipe } => {
+                    return pipe.poll(cx);
+                }
+            };
+            me.state.set(next);
+        }
+    }
+}
+
+impl<F, B, E> Future for H2Stream<F, B>
+where
+    F: Future<Output = Result<Response<B>, E>>,
+    B: HttpBody,
+    B::Data: 'static,
+    B::Error: Into<Box<dyn StdError + Send + Sync>>,
+    E: Into<Box<dyn StdError + Send + Sync>>,
+{
+    type Output = ();
+
+    fn poll(self: Pin<&mut Self>, cx: &mut task::Context<'_>) -> Poll<Self::Output> {
+        self.poll2(cx).map(|res| {
+            if let Err(e) = res {
+                debug!("stream error: {}", e);
+            }
+        })
+    }
+}

hyper/src/proto/mod.rs

@@ -0,0 +1,71 @@
+//! Pieces pertaining to the HTTP message protocol.
+
+cfg_feature! {
+    #![feature = "http1"]
+
+    pub(crate) mod h1;
+
+    pub(crate) use self::h1::Conn;
+
+    #[cfg(feature = "client")]
+    pub(crate) use self::h1::dispatch;
+    #[cfg(feature = "server")]
+    pub(crate) use self::h1::ServerTransaction;
+}
+
+#[cfg(feature = "http2")]
+pub(crate) mod h2;
+
+/// An Incoming Message head. Includes request/status line, and headers.
+#[derive(Debug, Default)]
+pub(crate) struct MessageHead<S> {
+    /// HTTP version of the message.
+    pub(crate) version: http::Version,
+    /// Subject (request line or status line) of Incoming message.
+    pub(crate) subject: S,
+    /// Headers of the Incoming message.
+    pub(crate) headers: http::HeaderMap,
+    /// Extensions.
+    extensions: http::Extensions,
+}
+
+/// An incoming request message.
+#[cfg(feature = "http1")]
+pub(crate) type RequestHead = MessageHead<RequestLine>;
+
+#[derive(Debug, Default, PartialEq)]
+#[cfg(feature = "http1")]
+pub(crate) struct RequestLine(pub(crate) http::Method, pub(crate) http::Uri);
+
+/// An incoming response message.
+#[cfg(all(feature = "http1", feature = "client"))]
+pub(crate) type ResponseHead = MessageHead<http::StatusCode>;
+
+#[derive(Debug)]
+#[cfg(feature = "http1")]
+pub(crate) enum BodyLength {
+    /// Content-Length
+    Known(u64),
+    /// Transfer-Encoding: chunked (if h1)
+    Unknown,
+}
+
+/// Status of when a Disaptcher future completes.
+pub(crate) enum Dispatched {
+    /// Dispatcher completely shutdown connection.
+    Shutdown,
+    /// Dispatcher has pending upgrade, and so did not shutdown.
+    #[cfg(feature = "http1")]
+    Upgrade(crate::upgrade::Pending),
+}
+
+impl MessageHead<http::StatusCode> {
+    fn into_response<B>(self, body: B) -> http::Response<B> {
+        let mut res = http::Response::new(body);
+        *res.status_mut() = self.subject;
+        *res.headers_mut() = self.headers;
+        *res.version_mut() = self.version;
+        *res.extensions_mut() = self.extensions;
+        res
+    }
+}