Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

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

1 files changed, 2847 insertions, 0 deletions

diff --git a/third_party/rust/hyper/src/proto/h1/role.rs b/third_party/rust/hyper/src/proto/h1/role.rs
new file mode 100644
index 0000000000..6252207baf
--- /dev/null
+++ b/third_party/rust/hyper/src/proto/h1/role.rs
@@ -0,0 +1,2847 @@
+use std::fmt::{self, Write};
+use std::mem::MaybeUninit;
+
+use bytes::Bytes;
+use bytes::BytesMut;
+#[cfg(feature = "server")]
+use http::header::ValueIter;
+use http::header::{self, Entry, HeaderName, HeaderValue};
+use http::{HeaderMap, Method, StatusCode, Version};
+#[cfg(all(feature = "server", feature = "runtime"))]
+use tokio::time::Instant;
+use tracing::{debug, error, trace, trace_span, warn};
+
+use crate::body::DecodedLength;
+#[cfg(feature = "server")]
+use crate::common::date;
+use crate::error::Parse;
+use crate::ext::HeaderCaseMap;
+#[cfg(feature = "ffi")]
+use crate::ext::OriginalHeaderOrder;
+use crate::headers;
+use crate::proto::h1::{
+    Encode, Encoder, Http1Transaction, ParseContext, ParseResult, ParsedMessage,
+};
+use crate::proto::{BodyLength, MessageHead, RequestHead, RequestLine};
+
+const MAX_HEADERS: usize = 100;
+const AVERAGE_HEADER_SIZE: usize = 30; // totally scientific
+#[cfg(feature = "server")]
+const MAX_URI_LEN: usize = (u16::MAX - 1) as usize;
+
+macro_rules! header_name {
+    ($bytes:expr) => {{
+        {
+            match HeaderName::from_bytes($bytes) {
+                Ok(name) => name,
+                Err(e) => maybe_panic!(e),
+            }
+        }
+    }};
+}
+
+macro_rules! header_value {
+    ($bytes:expr) => {{
+        {
+            unsafe { HeaderValue::from_maybe_shared_unchecked($bytes) }
+        }
+    }};
+}
+
+macro_rules! maybe_panic {
+    ($($arg:tt)*) => ({
+        let _err = ($($arg)*);
+        if cfg!(debug_assertions) {
+            panic!("{:?}", _err);
+        } else {
+            error!("Internal Hyper error, please report {:?}", _err);
+            return Err(Parse::Internal)
+        }
+    })
+}
+
+pub(super) fn parse_headers<T>(
+    bytes: &mut BytesMut,
+    ctx: ParseContext<'_>,
+) -> ParseResult<T::Incoming>
+where
+    T: Http1Transaction,
+{
+    // If the buffer is empty, don't bother entering the span, it's just noise.
+    if bytes.is_empty() {
+        return Ok(None);
+    }
+
+    let span = trace_span!("parse_headers");
+    let _s = span.enter();
+
+    #[cfg(all(feature = "server", feature = "runtime"))]
+    if !*ctx.h1_header_read_timeout_running {
+        if let Some(h1_header_read_timeout) = ctx.h1_header_read_timeout {
+            let deadline = Instant::now() + h1_header_read_timeout;
+            *ctx.h1_header_read_timeout_running = true;
+            match ctx.h1_header_read_timeout_fut {
+                Some(h1_header_read_timeout_fut) => {
+                    debug!("resetting h1 header read timeout timer");
+                    h1_header_read_timeout_fut.as_mut().reset(deadline);
+                }
+                None => {
+                    debug!("setting h1 header read timeout timer");
+                    *ctx.h1_header_read_timeout_fut =
+                        Some(Box::pin(tokio::time::sleep_until(deadline)));
+                }
+            }
+        }
+    }
+
+    T::parse(bytes, ctx)
+}
+
+pub(super) fn encode_headers<T>(
+    enc: Encode<'_, T::Outgoing>,
+    dst: &mut Vec<u8>,
+) -> crate::Result<Encoder>
+where
+    T: Http1Transaction,
+{
+    let span = trace_span!("encode_headers");
+    let _s = span.enter();
+    T::encode(enc, dst)
+}
+
+// There are 2 main roles, Client and Server.
+
+#[cfg(feature = "client")]
+pub(crate) enum Client {}
+
+#[cfg(feature = "server")]
+pub(crate) enum Server {}
+
+#[cfg(feature = "server")]
+impl Http1Transaction for Server {
+    type Incoming = RequestLine;
+    type Outgoing = StatusCode;
+    const LOG: &'static str = "{role=server}";
+
+    fn parse(buf: &mut BytesMut, ctx: ParseContext<'_>) -> ParseResult<RequestLine> {
+        debug_assert!(!buf.is_empty(), "parse called with empty buf");
+
+        let mut keep_alive;
+        let is_http_11;
+        let subject;
+        let version;
+        let len;
+        let headers_len;
+
+        // Unsafe: both headers_indices and headers are using uninitialized memory,
+        // but we *never* read any of it until after httparse has assigned
+        // values into it. By not zeroing out the stack memory, this saves
+        // a good ~5% on pipeline benchmarks.
+        let mut headers_indices: [MaybeUninit<HeaderIndices>; MAX_HEADERS] = unsafe {
+            // SAFETY: We can go safely from MaybeUninit array to array of MaybeUninit
+            MaybeUninit::uninit().assume_init()
+        };
+        {
+            /* SAFETY: it is safe to go from MaybeUninit array to array of MaybeUninit */
+            let mut headers: [MaybeUninit<httparse::Header<'_>>; MAX_HEADERS] =
+                unsafe { MaybeUninit::uninit().assume_init() };
+            trace!(bytes = buf.len(), "Request.parse");
+            let mut req = httparse::Request::new(&mut []);
+            let bytes = buf.as_ref();
+            match req.parse_with_uninit_headers(bytes, &mut headers) {
+                Ok(httparse::Status::Complete(parsed_len)) => {
+                    trace!("Request.parse Complete({})", parsed_len);
+                    len = parsed_len;
+                    let uri = req.path.unwrap();
+                    if uri.len() > MAX_URI_LEN {
+                        return Err(Parse::UriTooLong);
+                    }
+                    subject = RequestLine(
+                        Method::from_bytes(req.method.unwrap().as_bytes())?,
+                        uri.parse()?,
+                    );
+                    version = if req.version.unwrap() == 1 {
+                        keep_alive = true;
+                        is_http_11 = true;
+                        Version::HTTP_11
+                    } else {
+                        keep_alive = false;
+                        is_http_11 = false;
+                        Version::HTTP_10
+                    };
+
+                    record_header_indices(bytes, &req.headers, &mut headers_indices)?;
+                    headers_len = req.headers.len();
+                }
+                Ok(httparse::Status::Partial) => return Ok(None),
+                Err(err) => {
+                    return Err(match err {
+                        // if invalid Token, try to determine if for method or path
+                        httparse::Error::Token => {
+                            if req.method.is_none() {
+                                Parse::Method
+                            } else {
+                                debug_assert!(req.path.is_none());
+                                Parse::Uri
+                            }
+                        }
+                        other => other.into(),
+                    });
+                }
+            }
+        };
+
+        let slice = buf.split_to(len).freeze();
+
+        // According to https://tools.ietf.org/html/rfc7230#section-3.3.3
+        // 1. (irrelevant to Request)
+        // 2. (irrelevant to Request)
+        // 3. Transfer-Encoding: chunked has a chunked body.
+        // 4. If multiple differing Content-Length headers or invalid, close connection.
+        // 5. Content-Length header has a sized body.
+        // 6. Length 0.
+        // 7. (irrelevant to Request)
+
+        let mut decoder = DecodedLength::ZERO;
+        let mut expect_continue = false;
+        let mut con_len = None;
+        let mut is_te = false;
+        let mut is_te_chunked = false;
+        let mut wants_upgrade = subject.0 == Method::CONNECT;
+
+        let mut header_case_map = if ctx.preserve_header_case {
+            Some(HeaderCaseMap::default())
+        } else {
+            None
+        };
+
+        #[cfg(feature = "ffi")]
+        let mut header_order = if ctx.preserve_header_order {
+            Some(OriginalHeaderOrder::default())
+        } else {
+            None
+        };
+
+        let mut headers = ctx.cached_headers.take().unwrap_or_else(HeaderMap::new);
+
+        headers.reserve(headers_len);
+
+        for header in &headers_indices[..headers_len] {
+            // SAFETY: array is valid up to `headers_len`
+            let header = unsafe { &*header.as_ptr() };
+            let name = header_name!(&slice[header.name.0..header.name.1]);
+            let value = header_value!(slice.slice(header.value.0..header.value.1));
+
+            match name {
+                header::TRANSFER_ENCODING => {
+                    // https://tools.ietf.org/html/rfc7230#section-3.3.3
+                    // If Transfer-Encoding header is present, and 'chunked' is
+                    // not the final encoding, and this is a Request, then it is
+                    // malformed. A server should respond with 400 Bad Request.
+                    if !is_http_11 {
+                        debug!("HTTP/1.0 cannot have Transfer-Encoding header");
+                        return Err(Parse::transfer_encoding_unexpected());
+                    }
+                    is_te = true;
+                    if headers::is_chunked_(&value) {
+                        is_te_chunked = true;
+                        decoder = DecodedLength::CHUNKED;
+                    } else {
+                        is_te_chunked = false;
+                    }
+                }
+                header::CONTENT_LENGTH => {
+                    if is_te {
+                        continue;
+                    }
+                    let len = headers::content_length_parse(&value)
+                        .ok_or_else(Parse::content_length_invalid)?;
+                    if let Some(prev) = con_len {
+                        if prev != len {
+                            debug!(
+                                "multiple Content-Length headers with different values: [{}, {}]",
+                                prev, len,
+                            );
+                            return Err(Parse::content_length_invalid());
+                        }
+                        // we don't need to append this secondary length
+                        continue;
+                    }
+                    decoder = DecodedLength::checked_new(len)?;
+                    con_len = Some(len);
+                }
+                header::CONNECTION => {
+                    // keep_alive was previously set to default for Version
+                    if keep_alive {
+                        // HTTP/1.1
+                        keep_alive = !headers::connection_close(&value);
+                    } else {
+                        // HTTP/1.0
+                        keep_alive = headers::connection_keep_alive(&value);
+                    }
+                }
+                header::EXPECT => {
+                    // According to https://datatracker.ietf.org/doc/html/rfc2616#section-14.20
+                    // Comparison of expectation values is case-insensitive for unquoted tokens
+                    // (including the 100-continue token)
+                    expect_continue = value.as_bytes().eq_ignore_ascii_case(b"100-continue");
+                }
+                header::UPGRADE => {
+                    // Upgrades are only allowed with HTTP/1.1
+                    wants_upgrade = is_http_11;
+                }
+
+                _ => (),
+            }
+
+            if let Some(ref mut header_case_map) = header_case_map {
+                header_case_map.append(&name, slice.slice(header.name.0..header.name.1));
+            }
+
+            #[cfg(feature = "ffi")]
+            if let Some(ref mut header_order) = header_order {
+                header_order.append(&name);
+            }
+
+            headers.append(name, value);
+        }
+
+        if is_te && !is_te_chunked {
+            debug!("request with transfer-encoding header, but not chunked, bad request");
+            return Err(Parse::transfer_encoding_invalid());
+        }
+
+        let mut extensions = http::Extensions::default();
+
+        if let Some(header_case_map) = header_case_map {
+            extensions.insert(header_case_map);
+        }
+
+        #[cfg(feature = "ffi")]
+        if let Some(header_order) = header_order {
+            extensions.insert(header_order);
+        }
+
+        *ctx.req_method = Some(subject.0.clone());
+
+        Ok(Some(ParsedMessage {
+            head: MessageHead {
+                version,
+                subject,
+                headers,
+                extensions,
+            },
+            decode: decoder,
+            expect_continue,
+            keep_alive,
+            wants_upgrade,
+        }))
+    }
+
+    fn encode(mut msg: Encode<'_, Self::Outgoing>, dst: &mut Vec<u8>) -> crate::Result<Encoder> {
+        trace!(
+            "Server::encode status={:?}, body={:?}, req_method={:?}",
+            msg.head.subject,
+            msg.body,
+            msg.req_method
+        );
+
+        let mut wrote_len = false;
+
+        // hyper currently doesn't support returning 1xx status codes as a Response
+        // This is because Service only allows returning a single Response, and
+        // so if you try to reply with a e.g. 100 Continue, you have no way of
+        // replying with the latter status code response.
+        let (ret, is_last) = if msg.head.subject == StatusCode::SWITCHING_PROTOCOLS {
+            (Ok(()), true)
+        } else if msg.req_method == &Some(Method::CONNECT) && msg.head.subject.is_success() {
+            // Sending content-length or transfer-encoding header on 2xx response
+            // to CONNECT is forbidden in RFC 7231.
+            wrote_len = true;
+            (Ok(()), true)
+        } else if msg.head.subject.is_informational() {
+            warn!("response with 1xx status code not supported");
+            *msg.head = MessageHead::default();
+            msg.head.subject = StatusCode::INTERNAL_SERVER_ERROR;
+            msg.body = None;
+            (Err(crate::Error::new_user_unsupported_status_code()), true)
+        } else {
+            (Ok(()), !msg.keep_alive)
+        };
+
+        // In some error cases, we don't know about the invalid message until already
+        // pushing some bytes onto the `dst`. In those cases, we don't want to send
+        // the half-pushed message, so rewind to before.
+        let orig_len = dst.len();
+
+        let init_cap = 30 + msg.head.headers.len() * AVERAGE_HEADER_SIZE;
+        dst.reserve(init_cap);
+
+        let custom_reason_phrase = msg.head.extensions.get::<crate::ext::ReasonPhrase>();
+
+        if msg.head.version == Version::HTTP_11
+            && msg.head.subject == StatusCode::OK
+            && custom_reason_phrase.is_none()
+        {
+            extend(dst, b"HTTP/1.1 200 OK\r\n");
+        } else {
+            match msg.head.version {
+                Version::HTTP_10 => extend(dst, b"HTTP/1.0 "),
+                Version::HTTP_11 => extend(dst, b"HTTP/1.1 "),
+                Version::HTTP_2 => {
+                    debug!("response with HTTP2 version coerced to HTTP/1.1");
+                    extend(dst, b"HTTP/1.1 ");
+                }
+                other => panic!("unexpected response version: {:?}", other),
+            }
+
+            extend(dst, msg.head.subject.as_str().as_bytes());
+            extend(dst, b" ");
+
+            if let Some(reason) = custom_reason_phrase {
+                extend(dst, reason.as_bytes());
+            } else {
+                // a reason MUST be written, as many parsers will expect it.
+                extend(
+                    dst,
+                    msg.head
+                        .subject
+                        .canonical_reason()
+                        .unwrap_or("<none>")
+                        .as_bytes(),
+                );
+            }
+
+            extend(dst, b"\r\n");
+        }
+
+        let orig_headers;
+        let extensions = std::mem::take(&mut msg.head.extensions);
+        let orig_headers = match extensions.get::<HeaderCaseMap>() {
+            None if msg.title_case_headers => {
+                orig_headers = HeaderCaseMap::default();
+                Some(&orig_headers)
+            }
+            orig_headers => orig_headers,
+        };
+        let encoder = if let Some(orig_headers) = orig_headers {
+            Self::encode_headers_with_original_case(
+                msg,
+                dst,
+                is_last,
+                orig_len,
+                wrote_len,
+                orig_headers,
+            )?
+        } else {
+            Self::encode_headers_with_lower_case(msg, dst, is_last, orig_len, wrote_len)?
+        };
+
+        ret.map(|()| encoder)
+    }
+
+    fn on_error(err: &crate::Error) -> Option<MessageHead<Self::Outgoing>> {
+        use crate::error::Kind;
+        let status = match *err.kind() {
+            Kind::Parse(Parse::Method)
+            | Kind::Parse(Parse::Header(_))
+            | Kind::Parse(Parse::Uri)
+            | Kind::Parse(Parse::Version) => StatusCode::BAD_REQUEST,
+            Kind::Parse(Parse::TooLarge) => StatusCode::REQUEST_HEADER_FIELDS_TOO_LARGE,
+            Kind::Parse(Parse::UriTooLong) => StatusCode::URI_TOO_LONG,
+            _ => return None,
+        };
+
+        debug!("sending automatic response ({}) for parse error", status);
+        let mut msg = MessageHead::default();
+        msg.subject = status;
+        Some(msg)
+    }
+
+    fn is_server() -> bool {
+        true
+    }
+
+    fn update_date() {
+        date::update();
+    }
+}
+
+#[cfg(feature = "server")]
+impl Server {
+    fn can_have_body(method: &Option<Method>, status: StatusCode) -> bool {
+        Server::can_chunked(method, status)
+    }
+
+    fn can_chunked(method: &Option<Method>, status: StatusCode) -> bool {
+        if method == &Some(Method::HEAD) || method == &Some(Method::CONNECT) && status.is_success()
+        {
+            false
+        } else if status.is_informational() {
+            false
+        } else {
+            match status {
+                StatusCode::NO_CONTENT | StatusCode::NOT_MODIFIED => false,
+                _ => true,
+            }
+        }
+    }
+
+    fn can_have_content_length(method: &Option<Method>, status: StatusCode) -> bool {
+        if status.is_informational() || method == &Some(Method::CONNECT) && status.is_success() {
+            false
+        } else {
+            match status {
+                StatusCode::NO_CONTENT | StatusCode::NOT_MODIFIED => false,
+                _ => true,
+            }
+        }
+    }
+
+    fn can_have_implicit_zero_content_length(method: &Option<Method>, status: StatusCode) -> bool {
+        Server::can_have_content_length(method, status) && method != &Some(Method::HEAD)
+    }
+
+    fn encode_headers_with_lower_case(
+        msg: Encode<'_, StatusCode>,
+        dst: &mut Vec<u8>,
+        is_last: bool,
+        orig_len: usize,
+        wrote_len: bool,
+    ) -> crate::Result<Encoder> {
+        struct LowercaseWriter;
+
+        impl HeaderNameWriter for LowercaseWriter {
+            #[inline]
+            fn write_full_header_line(
+                &mut self,
+                dst: &mut Vec<u8>,
+                line: &str,
+                _: (HeaderName, &str),
+            ) {
+                extend(dst, line.as_bytes())
+            }
+
+            #[inline]
+            fn write_header_name_with_colon(
+                &mut self,
+                dst: &mut Vec<u8>,
+                name_with_colon: &str,
+                _: HeaderName,
+            ) {
+                extend(dst, name_with_colon.as_bytes())
+            }
+
+            #[inline]
+            fn write_header_name(&mut self, dst: &mut Vec<u8>, name: &HeaderName) {
+                extend(dst, name.as_str().as_bytes())
+            }
+        }
+
+        Self::encode_headers(msg, dst, is_last, orig_len, wrote_len, LowercaseWriter)
+    }
+
+    #[cold]
+    #[inline(never)]
+    fn encode_headers_with_original_case(
+        msg: Encode<'_, StatusCode>,
+        dst: &mut Vec<u8>,
+        is_last: bool,
+        orig_len: usize,
+        wrote_len: bool,
+        orig_headers: &HeaderCaseMap,
+    ) -> crate::Result<Encoder> {
+        struct OrigCaseWriter<'map> {
+            map: &'map HeaderCaseMap,
+            current: Option<(HeaderName, ValueIter<'map, Bytes>)>,
+            title_case_headers: bool,
+        }
+
+        impl HeaderNameWriter for OrigCaseWriter<'_> {
+            #[inline]
+            fn write_full_header_line(
+                &mut self,
+                dst: &mut Vec<u8>,
+                _: &str,
+                (name, rest): (HeaderName, &str),
+            ) {
+                self.write_header_name(dst, &name);
+                extend(dst, rest.as_bytes());
+            }
+
+            #[inline]
+            fn write_header_name_with_colon(
+                &mut self,
+                dst: &mut Vec<u8>,
+                _: &str,
+                name: HeaderName,
+            ) {
+                self.write_header_name(dst, &name);
+                extend(dst, b": ");
+            }
+
+            #[inline]
+            fn write_header_name(&mut self, dst: &mut Vec<u8>, name: &HeaderName) {
+                let Self {
+                    map,
+                    ref mut current,
+                    title_case_headers,
+                } = *self;
+                if current.as_ref().map_or(true, |(last, _)| last != name) {
+                    *current = None;
+                }
+                let (_, values) =
+                    current.get_or_insert_with(|| (name.clone(), map.get_all_internal(name)));
+
+                if let Some(orig_name) = values.next() {
+                    extend(dst, orig_name);
+                } else if title_case_headers {
+                    title_case(dst, name.as_str().as_bytes());
+                } else {
+                    extend(dst, name.as_str().as_bytes());
+                }
+            }
+        }
+
+        let header_name_writer = OrigCaseWriter {
+            map: orig_headers,
+            current: None,
+            title_case_headers: msg.title_case_headers,
+        };
+
+        Self::encode_headers(msg, dst, is_last, orig_len, wrote_len, header_name_writer)
+    }
+
+    #[inline]
+    fn encode_headers<W>(
+        msg: Encode<'_, StatusCode>,
+        dst: &mut Vec<u8>,
+        mut is_last: bool,
+        orig_len: usize,
+        mut wrote_len: bool,
+        mut header_name_writer: W,
+    ) -> crate::Result<Encoder>
+    where
+        W: HeaderNameWriter,
+    {
+        // In some error cases, we don't know about the invalid message until already
+        // pushing some bytes onto the `dst`. In those cases, we don't want to send
+        // the half-pushed message, so rewind to before.
+        let rewind = |dst: &mut Vec<u8>| {
+            dst.truncate(orig_len);
+        };
+
+        let mut encoder = Encoder::length(0);
+        let mut wrote_date = false;
+        let mut cur_name = None;
+        let mut is_name_written = false;
+        let mut must_write_chunked = false;
+        let mut prev_con_len = None;
+
+        macro_rules! handle_is_name_written {
+            () => {{
+                if is_name_written {
+                    // we need to clean up and write the newline
+                    debug_assert_ne!(
+                        &dst[dst.len() - 2..],
+                        b"\r\n",
+                        "previous header wrote newline but set is_name_written"
+                    );
+
+                    if must_write_chunked {
+                        extend(dst, b", chunked\r\n");
+                    } else {
+                        extend(dst, b"\r\n");
+                    }
+                }
+            }};
+        }
+
+        'headers: for (opt_name, value) in msg.head.headers.drain() {
+            if let Some(n) = opt_name {
+                cur_name = Some(n);
+                handle_is_name_written!();
+                is_name_written = false;
+            }
+            let name = cur_name.as_ref().expect("current header name");
+            match *name {
+                header::CONTENT_LENGTH => {
+                    if wrote_len && !is_name_written {
+                        warn!("unexpected content-length found, canceling");
+                        rewind(dst);
+                        return Err(crate::Error::new_user_header());
+                    }
+                    match msg.body {
+                        Some(BodyLength::Known(known_len)) => {
+                            // The HttpBody claims to know a length, and
+                            // the headers are already set. For performance
+                            // reasons, we are just going to trust that
+                            // the values match.
+                            //
+                            // In debug builds, we'll assert they are the
+                            // same to help developers find bugs.
+                            #[cfg(debug_assertions)]
+                            {
+                                if let Some(len) = headers::content_length_parse(&value) {
+                                    assert!(
+                                        len == known_len,
+                                        "payload claims content-length of {}, custom content-length header claims {}",
+                                        known_len,
+                                        len,
+                                    );
+                                }
+                            }
+
+                            if !is_name_written {
+                                encoder = Encoder::length(known_len);
+                                header_name_writer.write_header_name_with_colon(
+                                    dst,
+                                    "content-length: ",
+                                    header::CONTENT_LENGTH,
+                                );
+                                extend(dst, value.as_bytes());
+                                wrote_len = true;
+                                is_name_written = true;
+                            }
+                            continue 'headers;
+                        }
+                        Some(BodyLength::Unknown) => {
+                            // The HttpBody impl didn't know how long the
+                            // body is, but a length header was included.
+                            // We have to parse the value to return our
+                            // Encoder...
+
+                            if let Some(len) = headers::content_length_parse(&value) {
+                                if let Some(prev) = prev_con_len {
+                                    if prev != len {
+                                        warn!(
+                                            "multiple Content-Length values found: [{}, {}]",
+                                            prev, len
+                                        );
+                                        rewind(dst);
+                                        return Err(crate::Error::new_user_header());
+                                    }
+                                    debug_assert!(is_name_written);
+                                    continue 'headers;
+                                } else {
+                                    // we haven't written content-length yet!
+                                    encoder = Encoder::length(len);
+                                    header_name_writer.write_header_name_with_colon(
+                                        dst,
+                                        "content-length: ",
+                                        header::CONTENT_LENGTH,
+                                    );
+                                    extend(dst, value.as_bytes());
+                                    wrote_len = true;
+                                    is_name_written = true;
+                                    prev_con_len = Some(len);
+                                    continue 'headers;
+                                }
+                            } else {
+                                warn!("illegal Content-Length value: {:?}", value);
+                                rewind(dst);
+                                return Err(crate::Error::new_user_header());
+                            }
+                        }
+                        None => {
+                            // We have no body to actually send,
+                            // but the headers claim a content-length.
+                            // There's only 2 ways this makes sense:
+                            //
+                            // - The header says the length is `0`.
+                            // - This is a response to a `HEAD` request.
+                            if msg.req_method == &Some(Method::HEAD) {
+                                debug_assert_eq!(encoder, Encoder::length(0));
+                            } else {
+                                if value.as_bytes() != b"0" {
+                                    warn!(
+                                        "content-length value found, but empty body provided: {:?}",
+                                        value
+                                    );
+                                }
+                                continue 'headers;
+                            }
+                        }
+                    }
+                    wrote_len = true;
+                }
+                header::TRANSFER_ENCODING => {
+                    if wrote_len && !is_name_written {
+                        warn!("unexpected transfer-encoding found, canceling");
+                        rewind(dst);
+                        return Err(crate::Error::new_user_header());
+                    }
+                    // check that we actually can send a chunked body...
+                    if msg.head.version == Version::HTTP_10
+                        || !Server::can_chunked(msg.req_method, msg.head.subject)
+                    {
+                        continue;
+                    }
+                    wrote_len = true;
+                    // Must check each value, because `chunked` needs to be the
+                    // last encoding, or else we add it.
+                    must_write_chunked = !headers::is_chunked_(&value);
+
+                    if !is_name_written {
+                        encoder = Encoder::chunked();
+                        is_name_written = true;
+                        header_name_writer.write_header_name_with_colon(
+                            dst,
+                            "transfer-encoding: ",
+                            header::TRANSFER_ENCODING,
+                        );
+                        extend(dst, value.as_bytes());
+                    } else {
+                        extend(dst, b", ");
+                        extend(dst, value.as_bytes());
+                    }
+                    continue 'headers;
+                }
+                header::CONNECTION => {
+                    if !is_last && headers::connection_close(&value) {
+                        is_last = true;
+                    }
+                    if !is_name_written {
+                        is_name_written = true;
+                        header_name_writer.write_header_name_with_colon(
+                            dst,
+                            "connection: ",
+                            header::CONNECTION,
+                        );
+                        extend(dst, value.as_bytes());
+                    } else {
+                        extend(dst, b", ");
+                        extend(dst, value.as_bytes());
+                    }
+                    continue 'headers;
+                }
+                header::DATE => {
+                    wrote_date = true;
+                }
+                _ => (),
+            }
+            //TODO: this should perhaps instead combine them into
+            //single lines, as RFC7230 suggests is preferable.
+
+            // non-special write Name and Value
+            debug_assert!(
+                !is_name_written,
+                "{:?} set is_name_written and didn't continue loop",
+                name,
+            );
+            header_name_writer.write_header_name(dst, name);
+            extend(dst, b": ");
+            extend(dst, value.as_bytes());
+            extend(dst, b"\r\n");
+        }
+
+        handle_is_name_written!();
+
+        if !wrote_len {
+            encoder = match msg.body {
+                Some(BodyLength::Unknown) => {
+                    if msg.head.version == Version::HTTP_10
+                        || !Server::can_chunked(msg.req_method, msg.head.subject)
+                    {
+                        Encoder::close_delimited()
+                    } else {
+                        header_name_writer.write_full_header_line(
+                            dst,
+                            "transfer-encoding: chunked\r\n",
+                            (header::TRANSFER_ENCODING, ": chunked\r\n"),
+                        );
+                        Encoder::chunked()
+                    }
+                }
+                None | Some(BodyLength::Known(0)) => {
+                    if Server::can_have_implicit_zero_content_length(
+                        msg.req_method,
+                        msg.head.subject,
+                    ) {
+                        header_name_writer.write_full_header_line(
+                            dst,
+                            "content-length: 0\r\n",
+                            (header::CONTENT_LENGTH, ": 0\r\n"),
+                        )
+                    }
+                    Encoder::length(0)
+                }
+                Some(BodyLength::Known(len)) => {
+                    if !Server::can_have_content_length(msg.req_method, msg.head.subject) {
+                        Encoder::length(0)
+                    } else {
+                        header_name_writer.write_header_name_with_colon(
+                            dst,
+                            "content-length: ",
+                            header::CONTENT_LENGTH,
+                        );
+                        extend(dst, ::itoa::Buffer::new().format(len).as_bytes());
+                        extend(dst, b"\r\n");
+                        Encoder::length(len)
+                    }
+                }
+            };
+        }
+
+        if !Server::can_have_body(msg.req_method, msg.head.subject) {
+            trace!(
+                "server body forced to 0; method={:?}, status={:?}",
+                msg.req_method,
+                msg.head.subject
+            );
+            encoder = Encoder::length(0);
+        }
+
+        // cached date is much faster than formatting every request
+        if !wrote_date {
+            dst.reserve(date::DATE_VALUE_LENGTH + 8);
+            header_name_writer.write_header_name_with_colon(dst, "date: ", header::DATE);
+            date::extend(dst);
+            extend(dst, b"\r\n\r\n");
+        } else {
+            extend(dst, b"\r\n");
+        }
+
+        Ok(encoder.set_last(is_last))
+    }
+}
+
+#[cfg(feature = "server")]
+trait HeaderNameWriter {
+    fn write_full_header_line(
+        &mut self,
+        dst: &mut Vec<u8>,
+        line: &str,
+        name_value_pair: (HeaderName, &str),
+    );
+    fn write_header_name_with_colon(
+        &mut self,
+        dst: &mut Vec<u8>,
+        name_with_colon: &str,
+        name: HeaderName,
+    );
+    fn write_header_name(&mut self, dst: &mut Vec<u8>, name: &HeaderName);
+}
+
+#[cfg(feature = "client")]
+impl Http1Transaction for Client {
+    type Incoming = StatusCode;
+    type Outgoing = RequestLine;
+    const LOG: &'static str = "{role=client}";
+
+    fn parse(buf: &mut BytesMut, ctx: ParseContext<'_>) -> ParseResult<StatusCode> {
+        debug_assert!(!buf.is_empty(), "parse called with empty buf");
+
+        // Loop to skip information status code headers (100 Continue, etc).
+        loop {
+            // Unsafe: see comment in Server Http1Transaction, above.
+            let mut headers_indices: [MaybeUninit<HeaderIndices>; MAX_HEADERS] = unsafe {
+                // SAFETY: We can go safely from MaybeUninit array to array of MaybeUninit
+                MaybeUninit::uninit().assume_init()
+            };
+            let (len, status, reason, version, headers_len) = {
+                // SAFETY: We can go safely from MaybeUninit array to array of MaybeUninit
+                let mut headers: [MaybeUninit<httparse::Header<'_>>; MAX_HEADERS] =
+                    unsafe { MaybeUninit::uninit().assume_init() };
+                trace!(bytes = buf.len(), "Response.parse");
+                let mut res = httparse::Response::new(&mut []);
+                let bytes = buf.as_ref();
+                match ctx.h1_parser_config.parse_response_with_uninit_headers(
+                    &mut res,
+                    bytes,
+                    &mut headers,
+                ) {
+                    Ok(httparse::Status::Complete(len)) => {
+                        trace!("Response.parse Complete({})", len);
+                        let status = StatusCode::from_u16(res.code.unwrap())?;
+
+                        let reason = {
+                            let reason = res.reason.unwrap();
+                            // Only save the reason phrase if it isn't the canonical reason
+                            if Some(reason) != status.canonical_reason() {
+                                Some(Bytes::copy_from_slice(reason.as_bytes()))
+                            } else {
+                                None
+                            }
+                        };
+
+                        let version = if res.version.unwrap() == 1 {
+                            Version::HTTP_11
+                        } else {
+                            Version::HTTP_10
+                        };
+                        record_header_indices(bytes, &res.headers, &mut headers_indices)?;
+                        let headers_len = res.headers.len();
+                        (len, status, reason, version, headers_len)
+                    }
+                    Ok(httparse::Status::Partial) => return Ok(None),
+                    Err(httparse::Error::Version) if ctx.h09_responses => {
+                        trace!("Response.parse accepted HTTP/0.9 response");
+
+                        (0, StatusCode::OK, None, Version::HTTP_09, 0)
+                    }
+                    Err(e) => return Err(e.into()),
+                }
+            };
+
+            let mut slice = buf.split_to(len);
+
+            if ctx
+                .h1_parser_config
+                .obsolete_multiline_headers_in_responses_are_allowed()
+            {
+                for header in &headers_indices[..headers_len] {
+                    // SAFETY: array is valid up to `headers_len`
+                    let header = unsafe { &*header.as_ptr() };
+                    for b in &mut slice[header.value.0..header.value.1] {
+                        if *b == b'\r' || *b == b'\n' {
+                            *b = b' ';
+                        }
+                    }
+                }
+            }
+
+            let slice = slice.freeze();
+
+            let mut headers = ctx.cached_headers.take().unwrap_or_else(HeaderMap::new);
+
+            let mut keep_alive = version == Version::HTTP_11;
+
+            let mut header_case_map = if ctx.preserve_header_case {
+                Some(HeaderCaseMap::default())
+            } else {
+                None
+            };
+
+            #[cfg(feature = "ffi")]
+            let mut header_order = if ctx.preserve_header_order {
+                Some(OriginalHeaderOrder::default())
+            } else {
+                None
+            };
+
+            headers.reserve(headers_len);
+            for header in &headers_indices[..headers_len] {
+                // SAFETY: array is valid up to `headers_len`
+                let header = unsafe { &*header.as_ptr() };
+                let name = header_name!(&slice[header.name.0..header.name.1]);
+                let value = header_value!(slice.slice(header.value.0..header.value.1));
+
+                if let header::CONNECTION = name {
+                    // keep_alive was previously set to default for Version
+                    if keep_alive {
+                        // HTTP/1.1
+                        keep_alive = !headers::connection_close(&value);
+                    } else {
+                        // HTTP/1.0
+                        keep_alive = headers::connection_keep_alive(&value);
+                    }
+                }
+
+                if let Some(ref mut header_case_map) = header_case_map {
+                    header_case_map.append(&name, slice.slice(header.name.0..header.name.1));
+                }
+
+                #[cfg(feature = "ffi")]
+                if let Some(ref mut header_order) = header_order {
+                    header_order.append(&name);
+                }
+
+                headers.append(name, value);
+            }
+
+            let mut extensions = http::Extensions::default();
+
+            if let Some(header_case_map) = header_case_map {
+                extensions.insert(header_case_map);
+            }
+
+            #[cfg(feature = "ffi")]
+            if let Some(header_order) = header_order {
+                extensions.insert(header_order);
+            }
+
+            if let Some(reason) = reason {
+                // Safety: httparse ensures that only valid reason phrase bytes are present in this
+                // field.
+                let reason = unsafe { crate::ext::ReasonPhrase::from_bytes_unchecked(reason) };
+                extensions.insert(reason);
+            }
+
+            #[cfg(feature = "ffi")]
+            if ctx.raw_headers {
+                extensions.insert(crate::ffi::RawHeaders(crate::ffi::hyper_buf(slice)));
+            }
+
+            let head = MessageHead {
+                version,
+                subject: status,
+                headers,
+                extensions,
+            };
+            if let Some((decode, is_upgrade)) = Client::decoder(&head, ctx.req_method)? {
+                return Ok(Some(ParsedMessage {
+                    head,
+                    decode,
+                    expect_continue: false,
+                    // a client upgrade means the connection can't be used
+                    // again, as it is definitely upgrading.
+                    keep_alive: keep_alive && !is_upgrade,
+                    wants_upgrade: is_upgrade,
+                }));
+            }
+
+            #[cfg(feature = "ffi")]
+            if head.subject.is_informational() {
+                if let Some(callback) = ctx.on_informational {
+                    callback.call(head.into_response(crate::Body::empty()));
+                }
+            }
+
+            // Parsing a 1xx response could have consumed the buffer, check if
+            // it is empty now...
+            if buf.is_empty() {
+                return Ok(None);
+            }
+        }
+    }
+
+    fn encode(msg: Encode<'_, Self::Outgoing>, dst: &mut Vec<u8>) -> crate::Result<Encoder> {
+        trace!(
+            "Client::encode method={:?}, body={:?}",
+            msg.head.subject.0,
+            msg.body
+        );
+
+        *msg.req_method = Some(msg.head.subject.0.clone());
+
+        let body = Client::set_length(msg.head, msg.body);
+
+        let init_cap = 30 + msg.head.headers.len() * AVERAGE_HEADER_SIZE;
+        dst.reserve(init_cap);
+
+        extend(dst, msg.head.subject.0.as_str().as_bytes());
+        extend(dst, b" ");
+        //TODO: add API to http::Uri to encode without std::fmt
+        let _ = write!(FastWrite(dst), "{} ", msg.head.subject.1);
+
+        match msg.head.version {
+            Version::HTTP_10 => extend(dst, b"HTTP/1.0"),
+            Version::HTTP_11 => extend(dst, b"HTTP/1.1"),
+            Version::HTTP_2 => {
+                debug!("request with HTTP2 version coerced to HTTP/1.1");
+                extend(dst, b"HTTP/1.1");
+            }
+            other => panic!("unexpected request version: {:?}", other),
+        }
+        extend(dst, b"\r\n");
+
+        if let Some(orig_headers) = msg.head.extensions.get::<HeaderCaseMap>() {
+            write_headers_original_case(
+                &msg.head.headers,
+                orig_headers,
+                dst,
+                msg.title_case_headers,
+            );
+        } else if msg.title_case_headers {
+            write_headers_title_case(&msg.head.headers, dst);
+        } else {
+            write_headers(&msg.head.headers, dst);
+        }
+
+        extend(dst, b"\r\n");
+        msg.head.headers.clear(); //TODO: remove when switching to drain()
+
+        Ok(body)
+    }
+
+    fn on_error(_err: &crate::Error) -> Option<MessageHead<Self::Outgoing>> {
+        // we can't tell the server about any errors it creates
+        None
+    }
+
+    fn is_client() -> bool {
+        true
+    }
+}
+
+#[cfg(feature = "client")]
+impl Client {
+    /// Returns Some(length, wants_upgrade) if successful.
+    ///
+    /// Returns None if this message head should be skipped (like a 100 status).
+    fn decoder(
+        inc: &MessageHead<StatusCode>,
+        method: &mut Option<Method>,
+    ) -> Result<Option<(DecodedLength, bool)>, Parse> {
+        // According to https://tools.ietf.org/html/rfc7230#section-3.3.3
+        // 1. HEAD responses, and Status 1xx, 204, and 304 cannot have a body.
+        // 2. Status 2xx to a CONNECT cannot have a body.
+        // 3. Transfer-Encoding: chunked has a chunked body.
+        // 4. If multiple differing Content-Length headers or invalid, close connection.
+        // 5. Content-Length header has a sized body.
+        // 6. (irrelevant to Response)
+        // 7. Read till EOF.
+
+        match inc.subject.as_u16() {
+            101 => {
+                return Ok(Some((DecodedLength::ZERO, true)));
+            }
+            100 | 102..=199 => {
+                trace!("ignoring informational response: {}", inc.subject.as_u16());
+                return Ok(None);
+            }
+            204 | 304 => return Ok(Some((DecodedLength::ZERO, false))),
+            _ => (),
+        }
+        match *method {
+            Some(Method::HEAD) => {
+                return Ok(Some((DecodedLength::ZERO, false)));
+            }
+            Some(Method::CONNECT) => {
+                if let 200..=299 = inc.subject.as_u16() {
+                    return Ok(Some((DecodedLength::ZERO, true)));
+                }
+            }
+            Some(_) => {}
+            None => {
+                trace!("Client::decoder is missing the Method");
+            }
+        }
+
+        if inc.headers.contains_key(header::TRANSFER_ENCODING) {
+            // https://tools.ietf.org/html/rfc7230#section-3.3.3
+            // If Transfer-Encoding header is present, and 'chunked' is
+            // not the final encoding, and this is a Request, then it is
+            // malformed. A server should respond with 400 Bad Request.
+            if inc.version == Version::HTTP_10 {
+                debug!("HTTP/1.0 cannot have Transfer-Encoding header");
+                Err(Parse::transfer_encoding_unexpected())
+            } else if headers::transfer_encoding_is_chunked(&inc.headers) {
+                Ok(Some((DecodedLength::CHUNKED, false)))
+            } else {
+                trace!("not chunked, read till eof");
+                Ok(Some((DecodedLength::CLOSE_DELIMITED, false)))
+            }
+        } else if let Some(len) = headers::content_length_parse_all(&inc.headers) {
+            Ok(Some((DecodedLength::checked_new(len)?, false)))
+        } else if inc.headers.contains_key(header::CONTENT_LENGTH) {
+            debug!("illegal Content-Length header");
+            Err(Parse::content_length_invalid())
+        } else {
+            trace!("neither Transfer-Encoding nor Content-Length");
+            Ok(Some((DecodedLength::CLOSE_DELIMITED, false)))
+        }
+    }
+    fn set_length(head: &mut RequestHead, body: Option<BodyLength>) -> Encoder {
+        let body = if let Some(body) = body {
+            body
+        } else {
+            head.headers.remove(header::TRANSFER_ENCODING);
+            return Encoder::length(0);
+        };
+
+        // HTTP/1.0 doesn't know about chunked
+        let can_chunked = head.version == Version::HTTP_11;
+        let headers = &mut head.headers;
+
+        // If the user already set specific headers, we should respect them, regardless
+        // of what the HttpBody knows about itself. They set them for a reason.
+
+        // Because of the borrow checker, we can't check the for an existing
+        // Content-Length header while holding an `Entry` for the Transfer-Encoding
+        // header, so unfortunately, we must do the check here, first.
+
+        let existing_con_len = headers::content_length_parse_all(headers);
+        let mut should_remove_con_len = false;
+
+        if !can_chunked {
+            // Chunked isn't legal, so if it is set, we need to remove it.
+            if headers.remove(header::TRANSFER_ENCODING).is_some() {
+                trace!("removing illegal transfer-encoding header");
+            }
+
+            return if let Some(len) = existing_con_len {
+                Encoder::length(len)
+            } else if let BodyLength::Known(len) = body {
+                set_content_length(headers, len)
+            } else {
+                // HTTP/1.0 client requests without a content-length
+                // cannot have any body at all.
+                Encoder::length(0)
+            };
+        }
+
+        // If the user set a transfer-encoding, respect that. Let's just
+        // make sure `chunked` is the final encoding.
+        let encoder = match headers.entry(header::TRANSFER_ENCODING) {
+            Entry::Occupied(te) => {
+                should_remove_con_len = true;
+                if headers::is_chunked(te.iter()) {
+                    Some(Encoder::chunked())
+                } else {
+                    warn!("user provided transfer-encoding does not end in 'chunked'");
+
+                    // There's a Transfer-Encoding, but it doesn't end in 'chunked'!
+                    // An example that could trigger this:
+                    //
+                    //     Transfer-Encoding: gzip
+                    //
+                    // This can be bad, depending on if this is a request or a
+                    // response.
+                    //
+                    // - A request is illegal if there is a `Transfer-Encoding`
+                    //   but it doesn't end in `chunked`.
+                    // - A response that has `Transfer-Encoding` but doesn't
+                    //   end in `chunked` isn't illegal, it just forces this
+                    //   to be close-delimited.
+                    //
+                    // We can try to repair this, by adding `chunked` ourselves.
+
+                    headers::add_chunked(te);
+                    Some(Encoder::chunked())
+                }
+            }
+            Entry::Vacant(te) => {
+                if let Some(len) = existing_con_len {
+                    Some(Encoder::length(len))
+                } else if let BodyLength::Unknown = body {
+                    // GET, HEAD, and CONNECT almost never have bodies.
+                    //
+                    // So instead of sending a "chunked" body with a 0-chunk,
+                    // assume no body here. If you *must* send a body,
+                    // set the headers explicitly.
+                    match head.subject.0 {
+                        Method::GET | Method::HEAD | Method::CONNECT => Some(Encoder::length(0)),
+                        _ => {
+                            te.insert(HeaderValue::from_static("chunked"));
+                            Some(Encoder::chunked())
+                        }
+                    }
+                } else {
+                    None
+                }
+            }
+        };
+
+        // This is because we need a second mutable borrow to remove
+        // content-length header.
+        if let Some(encoder) = encoder {
+            if should_remove_con_len && existing_con_len.is_some() {
+                headers.remove(header::CONTENT_LENGTH);
+            }
+            return encoder;
+        }
+
+        // User didn't set transfer-encoding, AND we know body length,
+        // so we can just set the Content-Length automatically.
+
+        let len = if let BodyLength::Known(len) = body {
+            len
+        } else {
+            unreachable!("BodyLength::Unknown would set chunked");
+        };
+
+        set_content_length(headers, len)
+    }
+}
+
+fn set_content_length(headers: &mut HeaderMap, len: u64) -> Encoder {
+    // At this point, there should not be a valid Content-Length
+    // header. However, since we'll be indexing in anyways, we can
+    // warn the user if there was an existing illegal header.
+    //
+    // Or at least, we can in theory. It's actually a little bit slower,
+    // so perhaps only do that while the user is developing/testing.
+
+    if cfg!(debug_assertions) {
+        match headers.entry(header::CONTENT_LENGTH) {
+            Entry::Occupied(mut cl) => {
+                // Internal sanity check, we should have already determined
+                // that the header was illegal before calling this function.
+                debug_assert!(headers::content_length_parse_all_values(cl.iter()).is_none());
+                // Uh oh, the user set `Content-Length` headers, but set bad ones.
+                // This would be an illegal message anyways, so let's try to repair
+                // with our known good length.
+                error!("user provided content-length header was invalid");
+
+                cl.insert(HeaderValue::from(len));
+                Encoder::length(len)
+            }
+            Entry::Vacant(cl) => {
+                cl.insert(HeaderValue::from(len));
+                Encoder::length(len)
+            }
+        }
+    } else {
+        headers.insert(header::CONTENT_LENGTH, HeaderValue::from(len));
+        Encoder::length(len)
+    }
+}
+
+#[derive(Clone, Copy)]
+struct HeaderIndices {
+    name: (usize, usize),
+    value: (usize, usize),
+}
+
+fn record_header_indices(
+    bytes: &[u8],
+    headers: &[httparse::Header<'_>],
+    indices: &mut [MaybeUninit<HeaderIndices>],
+) -> Result<(), crate::error::Parse> {
+    let bytes_ptr = bytes.as_ptr() as usize;
+
+    for (header, indices) in headers.iter().zip(indices.iter_mut()) {
+        if header.name.len() >= (1 << 16) {
+            debug!("header name larger than 64kb: {:?}", header.name);
+            return Err(crate::error::Parse::TooLarge);
+        }
+        let name_start = header.name.as_ptr() as usize - bytes_ptr;
+        let name_end = name_start + header.name.len();
+        let value_start = header.value.as_ptr() as usize - bytes_ptr;
+        let value_end = value_start + header.value.len();
+
+        // FIXME(maybe_uninit_extra)
+        // FIXME(addr_of)
+        // Currently we don't have `ptr::addr_of_mut` in stable rust or
+        // MaybeUninit::write, so this is some way of assigning into a MaybeUninit
+        // safely
+        let new_header_indices = HeaderIndices {
+            name: (name_start, name_end),
+            value: (value_start, value_end),
+        };
+        *indices = MaybeUninit::new(new_header_indices);
+    }
+
+    Ok(())
+}
+
+// Write header names as title case. The header name is assumed to be ASCII.
+fn title_case(dst: &mut Vec<u8>, name: &[u8]) {
+    dst.reserve(name.len());
+
+    // Ensure first character is uppercased
+    let mut prev = b'-';
+    for &(mut c) in name {
+        if prev == b'-' {
+            c.make_ascii_uppercase();
+        }
+        dst.push(c);
+        prev = c;
+    }
+}
+
+fn write_headers_title_case(headers: &HeaderMap, dst: &mut Vec<u8>) {
+    for (name, value) in headers {
+        title_case(dst, name.as_str().as_bytes());
+        extend(dst, b": ");
+        extend(dst, value.as_bytes());
+        extend(dst, b"\r\n");
+    }
+}
+
+fn write_headers(headers: &HeaderMap, dst: &mut Vec<u8>) {
+    for (name, value) in headers {
+        extend(dst, name.as_str().as_bytes());
+        extend(dst, b": ");
+        extend(dst, value.as_bytes());
+        extend(dst, b"\r\n");
+    }
+}
+
+#[cold]
+fn write_headers_original_case(
+    headers: &HeaderMap,
+    orig_case: &HeaderCaseMap,
+    dst: &mut Vec<u8>,
+    title_case_headers: bool,
+) {
+    // For each header name/value pair, there may be a value in the casemap
+    // that corresponds to the HeaderValue. So, we iterator all the keys,
+    // and for each one, try to pair the originally cased name with the value.
+    //
+    // TODO: consider adding http::HeaderMap::entries() iterator
+    for name in headers.keys() {
+        let mut names = orig_case.get_all(name);
+
+        for value in headers.get_all(name) {
+            if let Some(orig_name) = names.next() {
+                extend(dst, orig_name.as_ref());
+            } else if title_case_headers {
+                title_case(dst, name.as_str().as_bytes());
+            } else {
+                extend(dst, name.as_str().as_bytes());
+            }
+
+            // Wanted for curl test cases that send `X-Custom-Header:\r\n`
+            if value.is_empty() {
+                extend(dst, b":\r\n");
+            } else {
+                extend(dst, b": ");
+                extend(dst, value.as_bytes());
+                extend(dst, b"\r\n");
+            }
+        }
+    }
+}
+
+struct FastWrite<'a>(&'a mut Vec<u8>);
+
+impl<'a> fmt::Write for FastWrite<'a> {
+    #[inline]
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        extend(self.0, s.as_bytes());
+        Ok(())
+    }
+
+    #[inline]
+    fn write_fmt(&mut self, args: fmt::Arguments<'_>) -> fmt::Result {
+        fmt::write(self, args)
+    }
+}
+
+#[inline]
+fn extend(dst: &mut Vec<u8>, data: &[u8]) {
+    dst.extend_from_slice(data);
+}
+
+#[cfg(test)]
+mod tests {
+    use bytes::BytesMut;
+
+    use super::*;
+
+    #[test]
+    fn test_parse_request() {
+        let _ = pretty_env_logger::try_init();
+        let mut raw = BytesMut::from("GET /echo HTTP/1.1\r\nHost: hyper.rs\r\n\r\n");
+        let mut method = None;
+        let msg = Server::parse(
+            &mut raw,
+            ParseContext {
+                cached_headers: &mut None,
+                req_method: &mut method,
+                h1_parser_config: Default::default(),
+                #[cfg(feature = "runtime")]
+                h1_header_read_timeout: None,
+                #[cfg(feature = "runtime")]
+                h1_header_read_timeout_fut: &mut None,
+                #[cfg(feature = "runtime")]
+                h1_header_read_timeout_running: &mut false,
+                preserve_header_case: false,
+                #[cfg(feature = "ffi")]
+                preserve_header_order: false,
+                h09_responses: false,
+                #[cfg(feature = "ffi")]
+                on_informational: &mut None,
+                #[cfg(feature = "ffi")]
+                raw_headers: false,
+            },
+        )
+        .unwrap()
+        .unwrap();
+        assert_eq!(raw.len(), 0);
+        assert_eq!(msg.head.subject.0, crate::Method::GET);
+        assert_eq!(msg.head.subject.1, "/echo");
+        assert_eq!(msg.head.version, crate::Version::HTTP_11);
+        assert_eq!(msg.head.headers.len(), 1);
+        assert_eq!(msg.head.headers["Host"], "hyper.rs");
+        assert_eq!(method, Some(crate::Method::GET));
+    }
+
+    #[test]
+    fn test_parse_response() {
+        let _ = pretty_env_logger::try_init();
+        let mut raw = BytesMut::from("HTTP/1.1 200 OK\r\nContent-Length: 0\r\n\r\n");
+        let ctx = ParseContext {
+            cached_headers: &mut None,
+            req_method: &mut Some(crate::Method::GET),
+            h1_parser_config: Default::default(),
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout: None,
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout_fut: &mut None,
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout_running: &mut false,
+            preserve_header_case: false,
+            #[cfg(feature = "ffi")]
+            preserve_header_order: false,
+            h09_responses: false,
+            #[cfg(feature = "ffi")]
+            on_informational: &mut None,
+            #[cfg(feature = "ffi")]
+            raw_headers: false,
+        };
+        let msg = Client::parse(&mut raw, ctx).unwrap().unwrap();
+        assert_eq!(raw.len(), 0);
+        assert_eq!(msg.head.subject, crate::StatusCode::OK);
+        assert_eq!(msg.head.version, crate::Version::HTTP_11);
+        assert_eq!(msg.head.headers.len(), 1);
+        assert_eq!(msg.head.headers["Content-Length"], "0");
+    }
+
+    #[test]
+    fn test_parse_request_errors() {
+        let mut raw = BytesMut::from("GET htt:p// HTTP/1.1\r\nHost: hyper.rs\r\n\r\n");
+        let ctx = ParseContext {
+            cached_headers: &mut None,
+            req_method: &mut None,
+            h1_parser_config: Default::default(),
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout: None,
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout_fut: &mut None,
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout_running: &mut false,
+            preserve_header_case: false,
+            #[cfg(feature = "ffi")]
+            preserve_header_order: false,
+            h09_responses: false,
+            #[cfg(feature = "ffi")]
+            on_informational: &mut None,
+            #[cfg(feature = "ffi")]
+            raw_headers: false,
+        };
+        Server::parse(&mut raw, ctx).unwrap_err();
+    }
+
+    const H09_RESPONSE: &'static str = "Baguettes are super delicious, don't you agree?";
+
+    #[test]
+    fn test_parse_response_h09_allowed() {
+        let _ = pretty_env_logger::try_init();
+        let mut raw = BytesMut::from(H09_RESPONSE);
+        let ctx = ParseContext {
+            cached_headers: &mut None,
+            req_method: &mut Some(crate::Method::GET),
+            h1_parser_config: Default::default(),
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout: None,
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout_fut: &mut None,
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout_running: &mut false,
+            preserve_header_case: false,
+            #[cfg(feature = "ffi")]
+            preserve_header_order: false,
+            h09_responses: true,
+            #[cfg(feature = "ffi")]
+            on_informational: &mut None,
+            #[cfg(feature = "ffi")]
+            raw_headers: false,
+        };
+        let msg = Client::parse(&mut raw, ctx).unwrap().unwrap();
+        assert_eq!(raw, H09_RESPONSE);
+        assert_eq!(msg.head.subject, crate::StatusCode::OK);
+        assert_eq!(msg.head.version, crate::Version::HTTP_09);
+        assert_eq!(msg.head.headers.len(), 0);
+    }
+
+    #[test]
+    fn test_parse_response_h09_rejected() {
+        let _ = pretty_env_logger::try_init();
+        let mut raw = BytesMut::from(H09_RESPONSE);
+        let ctx = ParseContext {
+            cached_headers: &mut None,
+            req_method: &mut Some(crate::Method::GET),
+            h1_parser_config: Default::default(),
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout: None,
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout_fut: &mut None,
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout_running: &mut false,
+            preserve_header_case: false,
+            #[cfg(feature = "ffi")]
+            preserve_header_order: false,
+            h09_responses: false,
+            #[cfg(feature = "ffi")]
+            on_informational: &mut None,
+            #[cfg(feature = "ffi")]
+            raw_headers: false,
+        };
+        Client::parse(&mut raw, ctx).unwrap_err();
+        assert_eq!(raw, H09_RESPONSE);
+    }
+
+    const RESPONSE_WITH_WHITESPACE_BETWEEN_HEADER_NAME_AND_COLON: &'static str =
+        "HTTP/1.1 200 OK\r\nAccess-Control-Allow-Credentials : true\r\n\r\n";
+
+    #[test]
+    fn test_parse_allow_response_with_spaces_before_colons() {
+        use httparse::ParserConfig;
+
+        let _ = pretty_env_logger::try_init();
+        let mut raw = BytesMut::from(RESPONSE_WITH_WHITESPACE_BETWEEN_HEADER_NAME_AND_COLON);
+        let mut h1_parser_config = ParserConfig::default();
+        h1_parser_config.allow_spaces_after_header_name_in_responses(true);
+        let ctx = ParseContext {
+            cached_headers: &mut None,
+            req_method: &mut Some(crate::Method::GET),
+            h1_parser_config,
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout: None,
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout_fut: &mut None,
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout_running: &mut false,
+            preserve_header_case: false,
+            #[cfg(feature = "ffi")]
+            preserve_header_order: false,
+            h09_responses: false,
+            #[cfg(feature = "ffi")]
+            on_informational: &mut None,
+            #[cfg(feature = "ffi")]
+            raw_headers: false,
+        };
+        let msg = Client::parse(&mut raw, ctx).unwrap().unwrap();
+        assert_eq!(raw.len(), 0);
+        assert_eq!(msg.head.subject, crate::StatusCode::OK);
+        assert_eq!(msg.head.version, crate::Version::HTTP_11);
+        assert_eq!(msg.head.headers.len(), 1);
+        assert_eq!(msg.head.headers["Access-Control-Allow-Credentials"], "true");
+    }
+
+    #[test]
+    fn test_parse_reject_response_with_spaces_before_colons() {
+        let _ = pretty_env_logger::try_init();
+        let mut raw = BytesMut::from(RESPONSE_WITH_WHITESPACE_BETWEEN_HEADER_NAME_AND_COLON);
+        let ctx = ParseContext {
+            cached_headers: &mut None,
+            req_method: &mut Some(crate::Method::GET),
+            h1_parser_config: Default::default(),
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout: None,
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout_fut: &mut None,
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout_running: &mut false,
+            preserve_header_case: false,
+            #[cfg(feature = "ffi")]
+            preserve_header_order: false,
+            h09_responses: false,
+            #[cfg(feature = "ffi")]
+            on_informational: &mut None,
+            #[cfg(feature = "ffi")]
+            raw_headers: false,
+        };
+        Client::parse(&mut raw, ctx).unwrap_err();
+    }
+
+    #[test]
+    fn test_parse_preserve_header_case_in_request() {
+        let mut raw =
+            BytesMut::from("GET / HTTP/1.1\r\nHost: hyper.rs\r\nX-BREAD: baguette\r\n\r\n");
+        let ctx = ParseContext {
+            cached_headers: &mut None,
+            req_method: &mut None,
+            h1_parser_config: Default::default(),
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout: None,
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout_fut: &mut None,
+            #[cfg(feature = "runtime")]
+            h1_header_read_timeout_running: &mut false,
+            preserve_header_case: true,
+            #[cfg(feature = "ffi")]
+            preserve_header_order: false,
+            h09_responses: false,
+            #[cfg(feature = "ffi")]
+            on_informational: &mut None,
+            #[cfg(feature = "ffi")]
+            raw_headers: false,
+        };
+        let parsed_message = Server::parse(&mut raw, ctx).unwrap().unwrap();
+        let orig_headers = parsed_message
+            .head
+            .extensions
+            .get::<HeaderCaseMap>()
+            .unwrap();
+        assert_eq!(
+            orig_headers
+                .get_all_internal(&HeaderName::from_static("host"))
+                .into_iter()
+                .collect::<Vec<_>>(),
+            vec![&Bytes::from("Host")]
+        );
+        assert_eq!(
+            orig_headers
+                .get_all_internal(&HeaderName::from_static("x-bread"))
+                .into_iter()
+                .collect::<Vec<_>>(),
+            vec![&Bytes::from("X-BREAD")]
+        );
+    }
+
+    #[test]
+    fn test_decoder_request() {
+        fn parse(s: &str) -> ParsedMessage<RequestLine> {
+            let mut bytes = BytesMut::from(s);
+            Server::parse(
+                &mut bytes,
+                ParseContext {
+                    cached_headers: &mut None,
+                    req_method: &mut None,
+                    h1_parser_config: Default::default(),
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout: None,
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout_fut: &mut None,
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout_running: &mut false,
+                    preserve_header_case: false,
+                    #[cfg(feature = "ffi")]
+                    preserve_header_order: false,
+                    h09_responses: false,
+                    #[cfg(feature = "ffi")]
+                    on_informational: &mut None,
+                    #[cfg(feature = "ffi")]
+                    raw_headers: false,
+                },
+            )
+            .expect("parse ok")
+            .expect("parse complete")
+        }
+
+        fn parse_err(s: &str, comment: &str) -> crate::error::Parse {
+            let mut bytes = BytesMut::from(s);
+            Server::parse(
+                &mut bytes,
+                ParseContext {
+                    cached_headers: &mut None,
+                    req_method: &mut None,
+                    h1_parser_config: Default::default(),
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout: None,
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout_fut: &mut None,
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout_running: &mut false,
+                    preserve_header_case: false,
+                    #[cfg(feature = "ffi")]
+                    preserve_header_order: false,
+                    h09_responses: false,
+                    #[cfg(feature = "ffi")]
+                    on_informational: &mut None,
+                    #[cfg(feature = "ffi")]
+                    raw_headers: false,
+                },
+            )
+            .expect_err(comment)
+        }
+
+        // no length or transfer-encoding means 0-length body
+        assert_eq!(
+            parse(
+                "\
+                 GET / HTTP/1.1\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::ZERO
+        );
+
+        assert_eq!(
+            parse(
+                "\
+                 POST / HTTP/1.1\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::ZERO
+        );
+
+        // transfer-encoding: chunked
+        assert_eq!(
+            parse(
+                "\
+                 POST / HTTP/1.1\r\n\
+                 transfer-encoding: chunked\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::CHUNKED
+        );
+
+        assert_eq!(
+            parse(
+                "\
+                 POST / HTTP/1.1\r\n\
+                 transfer-encoding: gzip, chunked\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::CHUNKED
+        );
+
+        assert_eq!(
+            parse(
+                "\
+                 POST / HTTP/1.1\r\n\
+                 transfer-encoding: gzip\r\n\
+                 transfer-encoding: chunked\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::CHUNKED
+        );
+
+        // content-length
+        assert_eq!(
+            parse(
+                "\
+                 POST / HTTP/1.1\r\n\
+                 content-length: 10\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::new(10)
+        );
+
+        // transfer-encoding and content-length = chunked
+        assert_eq!(
+            parse(
+                "\
+                 POST / HTTP/1.1\r\n\
+                 content-length: 10\r\n\
+                 transfer-encoding: chunked\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::CHUNKED
+        );
+
+        assert_eq!(
+            parse(
+                "\
+                 POST / HTTP/1.1\r\n\
+                 transfer-encoding: chunked\r\n\
+                 content-length: 10\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::CHUNKED
+        );
+
+        assert_eq!(
+            parse(
+                "\
+                 POST / HTTP/1.1\r\n\
+                 transfer-encoding: gzip\r\n\
+                 content-length: 10\r\n\
+                 transfer-encoding: chunked\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::CHUNKED
+        );
+
+        // multiple content-lengths of same value are fine
+        assert_eq!(
+            parse(
+                "\
+                 POST / HTTP/1.1\r\n\
+                 content-length: 10\r\n\
+                 content-length: 10\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::new(10)
+        );
+
+        // multiple content-lengths with different values is an error
+        parse_err(
+            "\
+             POST / HTTP/1.1\r\n\
+             content-length: 10\r\n\
+             content-length: 11\r\n\
+             \r\n\
+             ",
+            "multiple content-lengths",
+        );
+
+        // content-length with prefix is not allowed
+        parse_err(
+            "\
+             POST / HTTP/1.1\r\n\
+             content-length: +10\r\n\
+             \r\n\
+             ",
+            "prefixed content-length",
+        );
+
+        // transfer-encoding that isn't chunked is an error
+        parse_err(
+            "\
+             POST / HTTP/1.1\r\n\
+             transfer-encoding: gzip\r\n\
+             \r\n\
+             ",
+            "transfer-encoding but not chunked",
+        );
+
+        parse_err(
+            "\
+             POST / HTTP/1.1\r\n\
+             transfer-encoding: chunked, gzip\r\n\
+             \r\n\
+             ",
+            "transfer-encoding doesn't end in chunked",
+        );
+
+        parse_err(
+            "\
+             POST / HTTP/1.1\r\n\
+             transfer-encoding: chunked\r\n\
+             transfer-encoding: afterlol\r\n\
+             \r\n\
+             ",
+            "transfer-encoding multiple lines doesn't end in chunked",
+        );
+
+        // http/1.0
+
+        assert_eq!(
+            parse(
+                "\
+                 POST / HTTP/1.0\r\n\
+                 content-length: 10\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::new(10)
+        );
+
+        // 1.0 doesn't understand chunked, so its an error
+        parse_err(
+            "\
+             POST / HTTP/1.0\r\n\
+             transfer-encoding: chunked\r\n\
+             \r\n\
+             ",
+            "1.0 chunked",
+        );
+    }
+
+    #[test]
+    fn test_decoder_response() {
+        fn parse(s: &str) -> ParsedMessage<StatusCode> {
+            parse_with_method(s, Method::GET)
+        }
+
+        fn parse_ignores(s: &str) {
+            let mut bytes = BytesMut::from(s);
+            assert!(Client::parse(
+                &mut bytes,
+                ParseContext {
+                    cached_headers: &mut None,
+                    req_method: &mut Some(Method::GET),
+                    h1_parser_config: Default::default(),
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout: None,
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout_fut: &mut None,
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout_running: &mut false,
+                    preserve_header_case: false,
+                    #[cfg(feature = "ffi")]
+                    preserve_header_order: false,
+                    h09_responses: false,
+                    #[cfg(feature = "ffi")]
+                    on_informational: &mut None,
+                    #[cfg(feature = "ffi")]
+                    raw_headers: false,
+                }
+            )
+            .expect("parse ok")
+            .is_none())
+        }
+
+        fn parse_with_method(s: &str, m: Method) -> ParsedMessage<StatusCode> {
+            let mut bytes = BytesMut::from(s);
+            Client::parse(
+                &mut bytes,
+                ParseContext {
+                    cached_headers: &mut None,
+                    req_method: &mut Some(m),
+                    h1_parser_config: Default::default(),
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout: None,
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout_fut: &mut None,
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout_running: &mut false,
+                    preserve_header_case: false,
+                    #[cfg(feature = "ffi")]
+                    preserve_header_order: false,
+                    h09_responses: false,
+                    #[cfg(feature = "ffi")]
+                    on_informational: &mut None,
+                    #[cfg(feature = "ffi")]
+                    raw_headers: false,
+                },
+            )
+            .expect("parse ok")
+            .expect("parse complete")
+        }
+
+        fn parse_err(s: &str) -> crate::error::Parse {
+            let mut bytes = BytesMut::from(s);
+            Client::parse(
+                &mut bytes,
+                ParseContext {
+                    cached_headers: &mut None,
+                    req_method: &mut Some(Method::GET),
+                    h1_parser_config: Default::default(),
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout: None,
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout_fut: &mut None,
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout_running: &mut false,
+                    preserve_header_case: false,
+                    #[cfg(feature = "ffi")]
+                    preserve_header_order: false,
+                    h09_responses: false,
+                    #[cfg(feature = "ffi")]
+                    on_informational: &mut None,
+                    #[cfg(feature = "ffi")]
+                    raw_headers: false,
+                },
+            )
+            .expect_err("parse should err")
+        }
+
+        // no content-length or transfer-encoding means close-delimited
+        assert_eq!(
+            parse(
+                "\
+                 HTTP/1.1 200 OK\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::CLOSE_DELIMITED
+        );
+
+        // 204 and 304 never have a body
+        assert_eq!(
+            parse(
+                "\
+                 HTTP/1.1 204 No Content\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::ZERO
+        );
+
+        assert_eq!(
+            parse(
+                "\
+                 HTTP/1.1 304 Not Modified\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::ZERO
+        );
+
+        // content-length
+        assert_eq!(
+            parse(
+                "\
+                 HTTP/1.1 200 OK\r\n\
+                 content-length: 8\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::new(8)
+        );
+
+        assert_eq!(
+            parse(
+                "\
+                 HTTP/1.1 200 OK\r\n\
+                 content-length: 8\r\n\
+                 content-length: 8\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::new(8)
+        );
+
+        parse_err(
+            "\
+             HTTP/1.1 200 OK\r\n\
+             content-length: 8\r\n\
+             content-length: 9\r\n\
+             \r\n\
+             ",
+        );
+
+        parse_err(
+            "\
+             HTTP/1.1 200 OK\r\n\
+             content-length: +8\r\n\
+             \r\n\
+             ",
+        );
+
+        // transfer-encoding: chunked
+        assert_eq!(
+            parse(
+                "\
+                 HTTP/1.1 200 OK\r\n\
+                 transfer-encoding: chunked\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::CHUNKED
+        );
+
+        // transfer-encoding not-chunked is close-delimited
+        assert_eq!(
+            parse(
+                "\
+                 HTTP/1.1 200 OK\r\n\
+                 transfer-encoding: yolo\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::CLOSE_DELIMITED
+        );
+
+        // transfer-encoding and content-length = chunked
+        assert_eq!(
+            parse(
+                "\
+                 HTTP/1.1 200 OK\r\n\
+                 content-length: 10\r\n\
+                 transfer-encoding: chunked\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::CHUNKED
+        );
+
+        // HEAD can have content-length, but not body
+        assert_eq!(
+            parse_with_method(
+                "\
+                 HTTP/1.1 200 OK\r\n\
+                 content-length: 8\r\n\
+                 \r\n\
+                 ",
+                Method::HEAD
+            )
+            .decode,
+            DecodedLength::ZERO
+        );
+
+        // CONNECT with 200 never has body
+        {
+            let msg = parse_with_method(
+                "\
+                 HTTP/1.1 200 OK\r\n\
+                 \r\n\
+                 ",
+                Method::CONNECT,
+            );
+            assert_eq!(msg.decode, DecodedLength::ZERO);
+            assert!(!msg.keep_alive, "should be upgrade");
+            assert!(msg.wants_upgrade, "should be upgrade");
+        }
+
+        // CONNECT receiving non 200 can have a body
+        assert_eq!(
+            parse_with_method(
+                "\
+                 HTTP/1.1 400 Bad Request\r\n\
+                 \r\n\
+                 ",
+                Method::CONNECT
+            )
+            .decode,
+            DecodedLength::CLOSE_DELIMITED
+        );
+
+        // 1xx status codes
+        parse_ignores(
+            "\
+             HTTP/1.1 100 Continue\r\n\
+             \r\n\
+             ",
+        );
+
+        parse_ignores(
+            "\
+             HTTP/1.1 103 Early Hints\r\n\
+             \r\n\
+             ",
+        );
+
+        // 101 upgrade not supported yet
+        {
+            let msg = parse(
+                "\
+                 HTTP/1.1 101 Switching Protocols\r\n\
+                 \r\n\
+                 ",
+            );
+            assert_eq!(msg.decode, DecodedLength::ZERO);
+            assert!(!msg.keep_alive, "should be last");
+            assert!(msg.wants_upgrade, "should be upgrade");
+        }
+
+        // http/1.0
+        assert_eq!(
+            parse(
+                "\
+                 HTTP/1.0 200 OK\r\n\
+                 \r\n\
+                 "
+            )
+            .decode,
+            DecodedLength::CLOSE_DELIMITED
+        );
+
+        // 1.0 doesn't understand chunked
+        parse_err(
+            "\
+             HTTP/1.0 200 OK\r\n\
+             transfer-encoding: chunked\r\n\
+             \r\n\
+             ",
+        );
+
+        // keep-alive
+        assert!(
+            parse(
+                "\
+                 HTTP/1.1 200 OK\r\n\
+                 content-length: 0\r\n\
+                 \r\n\
+                 "
+            )
+            .keep_alive,
+            "HTTP/1.1 keep-alive is default"
+        );
+
+        assert!(
+            !parse(
+                "\
+                 HTTP/1.1 200 OK\r\n\
+                 content-length: 0\r\n\
+                 connection: foo, close, bar\r\n\
+                 \r\n\
+                 "
+            )
+            .keep_alive,
+            "connection close is always close"
+        );
+
+        assert!(
+            !parse(
+                "\
+                 HTTP/1.0 200 OK\r\n\
+                 content-length: 0\r\n\
+                 \r\n\
+                 "
+            )
+            .keep_alive,
+            "HTTP/1.0 close is default"
+        );
+
+        assert!(
+            parse(
+                "\
+                 HTTP/1.0 200 OK\r\n\
+                 content-length: 0\r\n\
+                 connection: foo, keep-alive, bar\r\n\
+                 \r\n\
+                 "
+            )
+            .keep_alive,
+            "connection keep-alive is always keep-alive"
+        );
+    }
+
+    #[test]
+    fn test_client_request_encode_title_case() {
+        use crate::proto::BodyLength;
+        use http::header::HeaderValue;
+
+        let mut head = MessageHead::default();
+        head.headers
+            .insert("content-length", HeaderValue::from_static("10"));
+        head.headers
+            .insert("content-type", HeaderValue::from_static("application/json"));
+        head.headers.insert("*-*", HeaderValue::from_static("o_o"));
+
+        let mut vec = Vec::new();
+        Client::encode(
+            Encode {
+                head: &mut head,
+                body: Some(BodyLength::Known(10)),
+                keep_alive: true,
+                req_method: &mut None,
+                title_case_headers: true,
+            },
+            &mut vec,
+        )
+        .unwrap();
+
+        assert_eq!(vec, b"GET / HTTP/1.1\r\nContent-Length: 10\r\nContent-Type: application/json\r\n*-*: o_o\r\n\r\n".to_vec());
+    }
+
+    #[test]
+    fn test_client_request_encode_orig_case() {
+        use crate::proto::BodyLength;
+        use http::header::{HeaderValue, CONTENT_LENGTH};
+
+        let mut head = MessageHead::default();
+        head.headers
+            .insert("content-length", HeaderValue::from_static("10"));
+        head.headers
+            .insert("content-type", HeaderValue::from_static("application/json"));
+
+        let mut orig_headers = HeaderCaseMap::default();
+        orig_headers.insert(CONTENT_LENGTH, "CONTENT-LENGTH".into());
+        head.extensions.insert(orig_headers);
+
+        let mut vec = Vec::new();
+        Client::encode(
+            Encode {
+                head: &mut head,
+                body: Some(BodyLength::Known(10)),
+                keep_alive: true,
+                req_method: &mut None,
+                title_case_headers: false,
+            },
+            &mut vec,
+        )
+        .unwrap();
+
+        assert_eq!(
+            &*vec,
+            b"GET / HTTP/1.1\r\nCONTENT-LENGTH: 10\r\ncontent-type: application/json\r\n\r\n"
+                .as_ref(),
+        );
+    }
+    #[test]
+    fn test_client_request_encode_orig_and_title_case() {
+        use crate::proto::BodyLength;
+        use http::header::{HeaderValue, CONTENT_LENGTH};
+
+        let mut head = MessageHead::default();
+        head.headers
+            .insert("content-length", HeaderValue::from_static("10"));
+        head.headers
+            .insert("content-type", HeaderValue::from_static("application/json"));
+
+        let mut orig_headers = HeaderCaseMap::default();
+        orig_headers.insert(CONTENT_LENGTH, "CONTENT-LENGTH".into());
+        head.extensions.insert(orig_headers);
+
+        let mut vec = Vec::new();
+        Client::encode(
+            Encode {
+                head: &mut head,
+                body: Some(BodyLength::Known(10)),
+                keep_alive: true,
+                req_method: &mut None,
+                title_case_headers: true,
+            },
+            &mut vec,
+        )
+        .unwrap();
+
+        assert_eq!(
+            &*vec,
+            b"GET / HTTP/1.1\r\nCONTENT-LENGTH: 10\r\nContent-Type: application/json\r\n\r\n"
+                .as_ref(),
+        );
+    }
+
+    #[test]
+    fn test_server_encode_connect_method() {
+        let mut head = MessageHead::default();
+
+        let mut vec = Vec::new();
+        let encoder = Server::encode(
+            Encode {
+                head: &mut head,
+                body: None,
+                keep_alive: true,
+                req_method: &mut Some(Method::CONNECT),
+                title_case_headers: false,
+            },
+            &mut vec,
+        )
+        .unwrap();
+
+        assert!(encoder.is_last());
+    }
+
+    #[test]
+    fn test_server_response_encode_title_case() {
+        use crate::proto::BodyLength;
+        use http::header::HeaderValue;
+
+        let mut head = MessageHead::default();
+        head.headers
+            .insert("content-length", HeaderValue::from_static("10"));
+        head.headers
+            .insert("content-type", HeaderValue::from_static("application/json"));
+        head.headers
+            .insert("weird--header", HeaderValue::from_static(""));
+
+        let mut vec = Vec::new();
+        Server::encode(
+            Encode {
+                head: &mut head,
+                body: Some(BodyLength::Known(10)),
+                keep_alive: true,
+                req_method: &mut None,
+                title_case_headers: true,
+            },
+            &mut vec,
+        )
+        .unwrap();
+
+        let expected_response =
+            b"HTTP/1.1 200 OK\r\nContent-Length: 10\r\nContent-Type: application/json\r\nWeird--Header: \r\n";
+
+        assert_eq!(&vec[..expected_response.len()], &expected_response[..]);
+    }
+
+    #[test]
+    fn test_server_response_encode_orig_case() {
+        use crate::proto::BodyLength;
+        use http::header::{HeaderValue, CONTENT_LENGTH};
+
+        let mut head = MessageHead::default();
+        head.headers
+            .insert("content-length", HeaderValue::from_static("10"));
+        head.headers
+            .insert("content-type", HeaderValue::from_static("application/json"));
+
+        let mut orig_headers = HeaderCaseMap::default();
+        orig_headers.insert(CONTENT_LENGTH, "CONTENT-LENGTH".into());
+        head.extensions.insert(orig_headers);
+
+        let mut vec = Vec::new();
+        Server::encode(
+            Encode {
+                head: &mut head,
+                body: Some(BodyLength::Known(10)),
+                keep_alive: true,
+                req_method: &mut None,
+                title_case_headers: false,
+            },
+            &mut vec,
+        )
+        .unwrap();
+
+        let expected_response =
+            b"HTTP/1.1 200 OK\r\nCONTENT-LENGTH: 10\r\ncontent-type: application/json\r\ndate: ";
+
+        assert_eq!(&vec[..expected_response.len()], &expected_response[..]);
+    }
+
+    #[test]
+    fn test_server_response_encode_orig_and_title_case() {
+        use crate::proto::BodyLength;
+        use http::header::{HeaderValue, CONTENT_LENGTH};
+
+        let mut head = MessageHead::default();
+        head.headers
+            .insert("content-length", HeaderValue::from_static("10"));
+        head.headers
+            .insert("content-type", HeaderValue::from_static("application/json"));
+
+        let mut orig_headers = HeaderCaseMap::default();
+        orig_headers.insert(CONTENT_LENGTH, "CONTENT-LENGTH".into());
+        head.extensions.insert(orig_headers);
+
+        let mut vec = Vec::new();
+        Server::encode(
+            Encode {
+                head: &mut head,
+                body: Some(BodyLength::Known(10)),
+                keep_alive: true,
+                req_method: &mut None,
+                title_case_headers: true,
+            },
+            &mut vec,
+        )
+        .unwrap();
+
+        let expected_response =
+            b"HTTP/1.1 200 OK\r\nCONTENT-LENGTH: 10\r\nContent-Type: application/json\r\nDate: ";
+
+        assert_eq!(&vec[..expected_response.len()], &expected_response[..]);
+    }
+
+    #[test]
+    fn parse_header_htabs() {
+        let mut bytes = BytesMut::from("HTTP/1.1 200 OK\r\nserver: hello\tworld\r\n\r\n");
+        let parsed = Client::parse(
+            &mut bytes,
+            ParseContext {
+                cached_headers: &mut None,
+                req_method: &mut Some(Method::GET),
+                h1_parser_config: Default::default(),
+                #[cfg(feature = "runtime")]
+                h1_header_read_timeout: None,
+                #[cfg(feature = "runtime")]
+                h1_header_read_timeout_fut: &mut None,
+                #[cfg(feature = "runtime")]
+                h1_header_read_timeout_running: &mut false,
+                preserve_header_case: false,
+                #[cfg(feature = "ffi")]
+                preserve_header_order: false,
+                h09_responses: false,
+                #[cfg(feature = "ffi")]
+                on_informational: &mut None,
+                #[cfg(feature = "ffi")]
+                raw_headers: false,
+            },
+        )
+        .expect("parse ok")
+        .expect("parse complete");
+
+        assert_eq!(parsed.head.headers["server"], "hello\tworld");
+    }
+
+    #[test]
+    fn test_write_headers_orig_case_empty_value() {
+        let mut headers = HeaderMap::new();
+        let name = http::header::HeaderName::from_static("x-empty");
+        headers.insert(&name, "".parse().expect("parse empty"));
+        let mut orig_cases = HeaderCaseMap::default();
+        orig_cases.insert(name, Bytes::from_static(b"X-EmptY"));
+
+        let mut dst = Vec::new();
+        super::write_headers_original_case(&headers, &orig_cases, &mut dst, false);
+
+        assert_eq!(
+            dst, b"X-EmptY:\r\n",
+            "there should be no space between the colon and CRLF"
+        );
+    }
+
+    #[test]
+    fn test_write_headers_orig_case_multiple_entries() {
+        let mut headers = HeaderMap::new();
+        let name = http::header::HeaderName::from_static("x-empty");
+        headers.insert(&name, "a".parse().unwrap());
+        headers.append(&name, "b".parse().unwrap());
+
+        let mut orig_cases = HeaderCaseMap::default();
+        orig_cases.insert(name.clone(), Bytes::from_static(b"X-Empty"));
+        orig_cases.append(name, Bytes::from_static(b"X-EMPTY"));
+
+        let mut dst = Vec::new();
+        super::write_headers_original_case(&headers, &orig_cases, &mut dst, false);
+
+        assert_eq!(dst, b"X-Empty: a\r\nX-EMPTY: b\r\n");
+    }
+
+    #[cfg(feature = "nightly")]
+    use test::Bencher;
+
+    #[cfg(feature = "nightly")]
+    #[bench]
+    fn bench_parse_incoming(b: &mut Bencher) {
+        let mut raw = BytesMut::from(
+            &b"GET /super_long_uri/and_whatever?what_should_we_talk_about/\
+            I_wonder/Hard_to_write_in_an_uri_after_all/you_have_to_make\
+            _up_the_punctuation_yourself/how_fun_is_that?test=foo&test1=\
+            foo1&test2=foo2&test3=foo3&test4=foo4 HTTP/1.1\r\nHost: \
+            hyper.rs\r\nAccept: a lot of things\r\nAccept-Charset: \
+            utf8\r\nAccept-Encoding: *\r\nAccess-Control-Allow-\
+            Credentials: None\r\nAccess-Control-Allow-Origin: None\r\n\
+            Access-Control-Allow-Methods: None\r\nAccess-Control-Allow-\
+            Headers: None\r\nContent-Encoding: utf8\r\nContent-Security-\
+            Policy: None\r\nContent-Type: text/html\r\nOrigin: hyper\
+            \r\nSec-Websocket-Extensions: It looks super important!\r\n\
+            Sec-Websocket-Origin: hyper\r\nSec-Websocket-Version: 4.3\r\
+            \nStrict-Transport-Security: None\r\nUser-Agent: hyper\r\n\
+            X-Content-Duration: None\r\nX-Content-Security-Policy: None\
+            \r\nX-DNSPrefetch-Control: None\r\nX-Frame-Options: \
+            Something important obviously\r\nX-Requested-With: Nothing\
+            \r\n\r\n"[..],
+        );
+        let len = raw.len();
+        let mut headers = Some(HeaderMap::new());
+
+        b.bytes = len as u64;
+        b.iter(|| {
+            let mut msg = Server::parse(
+                &mut raw,
+                ParseContext {
+                    cached_headers: &mut headers,
+                    req_method: &mut None,
+                    h1_parser_config: Default::default(),
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout: None,
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout_fut: &mut None,
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout_running: &mut false,
+                    preserve_header_case: false,
+                    #[cfg(feature = "ffi")]
+                    preserve_header_order: false,
+                    h09_responses: false,
+                    #[cfg(feature = "ffi")]
+                    on_informational: &mut None,
+                    #[cfg(feature = "ffi")]
+                    raw_headers: false,
+                },
+            )
+            .unwrap()
+            .unwrap();
+            ::test::black_box(&msg);
+            msg.head.headers.clear();
+            headers = Some(msg.head.headers);
+            restart(&mut raw, len);
+        });
+
+        fn restart(b: &mut BytesMut, len: usize) {
+            b.reserve(1);
+            unsafe {
+                b.set_len(len);
+            }
+        }
+    }
+
+    #[cfg(feature = "nightly")]
+    #[bench]
+    fn bench_parse_short(b: &mut Bencher) {
+        let s = &b"GET / HTTP/1.1\r\nHost: localhost:8080\r\n\r\n"[..];
+        let mut raw = BytesMut::from(s);
+        let len = raw.len();
+        let mut headers = Some(HeaderMap::new());
+
+        b.bytes = len as u64;
+        b.iter(|| {
+            let mut msg = Server::parse(
+                &mut raw,
+                ParseContext {
+                    cached_headers: &mut headers,
+                    req_method: &mut None,
+                    h1_parser_config: Default::default(),
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout: None,
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout_fut: &mut None,
+                    #[cfg(feature = "runtime")]
+                    h1_header_read_timeout_running: &mut false,
+                    preserve_header_case: false,
+                    #[cfg(feature = "ffi")]
+                    preserve_header_order: false,
+                    h09_responses: false,
+                    #[cfg(feature = "ffi")]
+                    on_informational: &mut None,
+                    #[cfg(feature = "ffi")]
+                    raw_headers: false,
+                },
+            )
+            .unwrap()
+            .unwrap();
+            ::test::black_box(&msg);
+            msg.head.headers.clear();
+            headers = Some(msg.head.headers);
+            restart(&mut raw, len);
+        });
+
+        fn restart(b: &mut BytesMut, len: usize) {
+            b.reserve(1);
+            unsafe {
+                b.set_len(len);
+            }
+        }
+    }
+
+    #[cfg(feature = "nightly")]
+    #[bench]
+    fn bench_server_encode_headers_preset(b: &mut Bencher) {
+        use crate::proto::BodyLength;
+        use http::header::HeaderValue;
+
+        let len = 108;
+        b.bytes = len as u64;
+
+        let mut head = MessageHead::default();
+        let mut headers = HeaderMap::new();
+        headers.insert("content-length", HeaderValue::from_static("10"));
+        headers.insert("content-type", HeaderValue::from_static("application/json"));
+
+        b.iter(|| {
+            let mut vec = Vec::new();
+            head.headers = headers.clone();
+            Server::encode(
+                Encode {
+                    head: &mut head,
+                    body: Some(BodyLength::Known(10)),
+                    keep_alive: true,
+                    req_method: &mut Some(Method::GET),
+                    title_case_headers: false,
+                },
+                &mut vec,
+            )
+            .unwrap();
+            assert_eq!(vec.len(), len);
+            ::test::black_box(vec);
+        })
+    }
+
+    #[cfg(feature = "nightly")]
+    #[bench]
+    fn bench_server_encode_no_headers(b: &mut Bencher) {
+        use crate::proto::BodyLength;
+
+        let len = 76;
+        b.bytes = len as u64;
+
+        let mut head = MessageHead::default();
+        let mut vec = Vec::with_capacity(128);
+
+        b.iter(|| {
+            Server::encode(
+                Encode {
+                    head: &mut head,
+                    body: Some(BodyLength::Known(10)),
+                    keep_alive: true,
+                    req_method: &mut Some(Method::GET),
+                    title_case_headers: false,
+                },
+                &mut vec,
+            )
+            .unwrap();
+            assert_eq!(vec.len(), len);
+            ::test::black_box(&vec);
+
+            vec.clear();
+        })
+    }
+}