feat(http1): Add higher-level HTTP upgrade support to Client and Server (#1563)

- Adds `Body::on_upgrade()` that returns an `OnUpgrade` future.
- Adds `hyper::upgrade` module containing types for dealing with
  upgrades.
- Adds `server::conn::Connection::with_upgrades()` method to enable
  these upgrades when using lower-level API (because of a missing
  `Send` bound on the transport generic).
- Client connections are automatically enabled.
- Optimizes request parsing, to make up for extra work to look for
  upgrade requests.
  - Returns a smaller `DecodedLength` type instead of the fatter
    `Decoder`, which should also allow a couple fewer branches.
  - Removes the `Decode::Ignore` wrapper enum, and instead ignoring
    1xx responses is handled directly in the response parsing code.

Ref #1563 

Closes #1395

src/proto/mod.rs

@@ -1,12 +1,12 @@
 //! Pieces pertaining to the HTTP message protocol.
 use http::{HeaderMap, Method, StatusCode, Uri, Version};
 
-pub(crate) use self::h1::{dispatch, Conn, ClientTransaction, ClientUpgradeTransaction, ServerTransaction};
+pub(crate) use self::h1::{dispatch, Conn, ServerTransaction};
+use self::body_length::DecodedLength;
 
 pub(crate) mod h1;
 pub(crate) mod h2;
 
-
 /// An Incoming Message head. Includes request/status line, and headers.
 #[derive(Clone, Debug, Default, PartialEq)]
 pub struct MessageHead<S> {
@@ -27,34 +27,6 @@ pub struct RequestLine(pub Method, pub Uri);
 /// An incoming response message.
 pub type ResponseHead = MessageHead<StatusCode>;
 
-/*
-impl<S> MessageHead<S> {
-    pub fn should_keep_alive(&self) -> bool {
-        should_keep_alive(self.version, &self.headers)
-    }
-
-    pub fn expecting_continue(&self) -> bool {
-        expecting_continue(self.version, &self.headers)
-    }
-}
-
-/// Checks if a connection should be kept alive.
-#[inline]
-pub fn should_keep_alive(version: Version, headers: &HeaderMap) -> bool {
-    if version == Version::HTTP_10 {
-        headers::connection_keep_alive(headers)
-    } else {
-        !headers::connection_close(headers)
-    }
-}
-
-/// Checks if a connection is expecting a `100 Continue` before sending its body.
-#[inline]
-pub fn expecting_continue(version: Version, headers: &HeaderMap) -> bool {
-    version == Version::HTTP_11 && headers::expect_continue(headers)
-}
-*/
-
 #[derive(Debug)]
 pub enum BodyLength {
     /// Content-Length
@@ -63,32 +35,72 @@ pub enum BodyLength {
     Unknown,
 }
 
-/*
-#[test]
-fn test_should_keep_alive() {
-    let mut headers = HeaderMap::new();
-
-    assert!(!should_keep_alive(Version::HTTP_10, &headers));
-    assert!(should_keep_alive(Version::HTTP_11, &headers));
-
-    headers.insert("connection", ::http::header::HeaderValue::from_static("close"));
-    assert!(!should_keep_alive(Version::HTTP_10, &headers));
-    assert!(!should_keep_alive(Version::HTTP_11, &headers));
-
-    headers.insert("connection", ::http::header::HeaderValue::from_static("keep-alive"));
-    assert!(should_keep_alive(Version::HTTP_10, &headers));
-    assert!(should_keep_alive(Version::HTTP_11, &headers));
+/// Status of when an Disaptcher future completes.
+pub(crate) enum Dispatched {
+    /// Dispatcher completely shutdown connection.
+    Shutdown,
+    /// Dispatcher has pending upgrade, and so did not shutdown.
+    Upgrade(::upgrade::Pending),
 }
 
-#[test]
-fn test_expecting_continue() {
-    let mut headers = HeaderMap::new();
+/// A separate module to encapsulate the invariants of the DecodedLength type.
+mod body_length {
+    use std::fmt;
 
-    assert!(!expecting_continue(Version::HTTP_10, &headers));
-    assert!(!expecting_continue(Version::HTTP_11, &headers));
+    #[derive(Clone, Copy, Debug, PartialEq, Eq)]
+    pub(crate) struct DecodedLength(u64);
 
-    headers.insert("expect", ::http::header::HeaderValue::from_static("100-continue"));
-    assert!(!expecting_continue(Version::HTTP_10, &headers));
-    assert!(expecting_continue(Version::HTTP_11, &headers));
+    const MAX_LEN: u64 = ::std::u64::MAX - 2;
+
+    impl DecodedLength {
+        pub(crate) const CLOSE_DELIMITED: DecodedLength = DecodedLength(::std::u64::MAX);
+        pub(crate) const CHUNKED: DecodedLength = DecodedLength(::std::u64::MAX - 1);
+        pub(crate) const ZERO: DecodedLength = DecodedLength(0);
+
+        #[cfg(test)]
+        pub(crate) fn new(len: u64) -> Self {
+            debug_assert!(len <= MAX_LEN);
+            DecodedLength(len)
+        }
+
+        /// Takes the length as a content-length without other checks.
+        ///
+        /// Should only be called if previously confirmed this isn't
+        /// CLOSE_DELIMITED or CHUNKED.
+        #[inline]
+        pub(crate) fn danger_len(self) -> u64 {
+            debug_assert!(self.0 < Self::CHUNKED.0);
+            self.0
+        }
+
+        /// Converts to an Option<u64> representing a Known or Unknown length.
+        pub(crate) fn into_opt(self) -> Option<u64> {
+            match self {
+                DecodedLength::CHUNKED |
+                DecodedLength::CLOSE_DELIMITED => None,
+                DecodedLength(known) => Some(known)
+            }
+        }
+
+        /// Checks the `u64` is within the maximum allowed for content-length.
+        pub(crate) fn checked_new(len: u64) -> Result<Self, ::error::Parse> {
+            if len <= MAX_LEN {
+                Ok(DecodedLength(len))
+            } else {
+                warn!("content-length bigger than maximum: {} > {}", len, MAX_LEN);
+                Err(::error::Parse::TooLarge)
+            }
+        }
+    }
+
+    impl fmt::Display for DecodedLength {
+        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+            match *self {
+                DecodedLength::CLOSE_DELIMITED => f.write_str("close-delimited"),
+                DecodedLength::CHUNKED => f.write_str("chunked encoding"),
+                DecodedLength::ZERO => f.write_str("empty"),
+                DecodedLength(n) => write!(f, "content-length ({} bytes)", n),
+            }
+        }
+    }
 }
-*/