feat(client): adds HttpInfo to responses when HttpConnector is used

- Adds `client::connect::Connected::extra()`, which allows connectors to
  specify arbitrary custom information about a connected transport.

If a connector provides this extra value, it will be set in the
`Response` extensions.

Closes #1402

Author: seanmonstar

Diff for: examples/hello.rs

@@ -10,7 +10,6 @@ static PHRASE: &'static [u8] = b"Hello World!";
 
 fn main() {
     pretty_env_logger::init();
-
     let addr = ([127, 0, 0, 1], 3000).into();
 
     // new_service is run for each connection, creating a 'service'

Diff for: src/client/connect.rs

@@ -6,14 +6,15 @@
 //!   establishes connections over TCP.
 //! - The [`Connect`](Connect) trait and related types to build custom connectors.
 use std::error::Error as StdError;
+use std::fmt;
 use std::mem;
 
 use bytes::{BufMut, BytesMut};
 use futures::Future;
-use http::{uri, Uri};
+use http::{uri, Response, Uri};
 use tokio_io::{AsyncRead, AsyncWrite};
 
-#[cfg(feature = "runtime")] pub use self::http::HttpConnector;
+#[cfg(feature = "runtime")] pub use self::http::{HttpConnector, HttpInfo};
 
 /// Connect to a destination, returning an IO transport.
 ///
@@ -46,8 +47,12 @@ pub struct Destination {
 pub struct Connected {
     //alpn: Alpn,
     pub(super) is_proxied: bool,
+    pub(super) extra: Option<Extra>,
 }
 
+pub(super) struct Extra(Box<FnClone>);
+
+
 /*TODO: when HTTP1 Upgrades to H2 are added, this will be needed
 #[derive(Debug)]
 pub(super) enum Alpn {
@@ -234,8 +239,8 @@ impl Connected {
     /// Create new `Connected` type with empty metadata.
     pub fn new() -> Connected {
         Connected {
-            //alpn: Alpn::Http1,
             is_proxied: false,
+            extra: None,
         }
     }
 
@@ -251,6 +256,15 @@ impl Connected {
         self
     }
 
+    /// Set extra connection information to be set in the extensions of every `Response`.
+    pub fn extra<T: Clone + Send + Sync + 'static>(mut self, extra: T) -> Connected {
+        self.extra = Some(Extra(Box::new(move |res: &mut Response<::Body>| {
+            let e = extra.clone();
+            res.extensions_mut().insert(e);
+        })));
+        self
+    }
+
     /*
     /// Set that the connected transport negotiated HTTP/2 as it's
     /// next protocol.
@@ -259,6 +273,54 @@ impl Connected {
         self
     }
     */
+
+    // Don't public expose that `Connected` is `Clone`, unsure if we want to
+    // keep that contract...
+    pub(super) fn clone(&self) -> Connected {
+        Connected {
+            is_proxied: self.is_proxied,
+            extra: self.extra.clone(),
+        }
+    }
+}
+
+// ===== impl Extra =====
+
+impl Extra {
+    pub(super) fn set(&self, res: &mut Response<::Body>) {
+        self.0.call(res);
+    }
+}
+
+impl Clone for Extra {
+    fn clone(&self) -> Extra {
+        Extra(self.0.clone_fn())
+    }
+}
+
+impl fmt::Debug for Extra {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("Extra")
+            .finish()
+    }
+}
+
+trait FnClone: Send + Sync {
+    fn clone_fn(&self) -> Box<FnClone>;
+    fn call(&self, res: &mut Response<::Body>);
+}
+
+impl<F> FnClone for F
+where
+    F: Fn(&mut Response<::Body>) + Clone + Send + Sync + 'static
+{
+    fn clone_fn(&self) -> Box<FnClone> {
+        Box::new(self.clone())
+    }
+
+    fn call(&self, res: &mut Response<::Body>) {
+        (*self)(res)
+    }
 }
 
 #[cfg(test)]
@@ -436,14 +498,50 @@ mod http {
     /// A connector for the `http` scheme.
     ///
     /// Performs DNS resolution in a thread pool, and then connects over TCP.
+    ///
+    /// # Note
+    ///
+    /// Sets the [`HttpInfo`](HttpInfo) value on responses, which includes
+    /// transport information such as the remote socket address used.
     #[derive(Clone)]
     pub struct HttpConnector {
         executor: HttpConnectExecutor,
         enforce_http: bool,
         handle: Option<Handle>,
         keep_alive_timeout: Option<Duration>,
-        nodelay: bool,
         local_address: Option<IpAddr>,
+        nodelay: bool,
+    }
+
+    /// Extra information about the transport when an HttpConnector is used.
+    ///
+    /// # Example
+    ///
+    /// ```rust
+    /// use hyper::client::{Client, connect::HttpInfo};
+    /// use hyper::rt::Future;
+    ///
+    /// let client = Client::new();
+    ///
+    /// let fut = client.get("http://example.local".parse().unwrap())
+    ///     .inspect(|resp| {
+    ///         let info = resp
+    ///             .extensions()
+    ///             .get::<HttpInfo>()
+    ///             .expect("HttpConnector sets HttpInfo");
+    ///
+    ///         println!("remote addr = {}", info.remote_addr());
+    ///     });
+    /// ```
+    ///
+    /// # Note
+    ///
+    /// If a different connector is used besides [`HttpConnector`](HttpConnector),
+    /// this value will not exist in the extensions. Consult that specific
+    /// connector to see what "extra" information it might provide to responses.
+    #[derive(Clone, Debug)]
+    pub struct HttpInfo {
+        remote_addr: SocketAddr,
     }
 
     impl HttpConnector {
@@ -600,6 +698,7 @@ mod http {
             }
         }
     }
+
     /// A Future representing work to connect to a URL.
     #[must_use = "futures do nothing unless polled"]
     pub struct HttpConnecting {
@@ -640,16 +739,12 @@ mod http {
                         }
                     },
                     State::Resolving(ref mut future, local_addr) => {
-                        match try!(future.poll()) {
-                            Async::NotReady => return Ok(Async::NotReady),
-                            Async::Ready(addrs) => {
-                                state = State::Connecting(ConnectingTcp {
-                                    addrs: addrs,
-                                    local_addr: local_addr,
-                                    current: None,
-                                })
-                            }
-                        };
+                        let addrs = try_ready!(future.poll());
+                        state = State::Connecting(ConnectingTcp {
+                            addrs: addrs,
+                            local_addr: local_addr,
+                            current: None,
+                        });
                     },
                     State::Connecting(ref mut c) => {
                         let sock = try_ready!(c.poll(&self.handle));
@@ -660,7 +755,13 @@ mod http {
 
                         sock.set_nodelay(self.nodelay)?;
 
-                        return Ok(Async::Ready((sock, Connected::new())));
+                        let extra = HttpInfo {
+                            remote_addr: sock.peer_addr()?,
+                        };
+                        let connected = Connected::new()
+                            .extra(extra);
+
+                        return Ok(Async::Ready((sock, connected)));
                     },
                     State::Error(ref mut e) => return Err(e.take().expect("polled more than once")),
                 }
@@ -710,6 +811,13 @@ mod http {
         }
     }
 
+    impl HttpInfo {
+        /// Get the remote address of the transport used.
+        pub fn remote_addr(&self) -> SocketAddr {
+            self.remote_addr
+        }
+    }
+
     // Make this Future unnameable outside of this crate.
     mod http_connector {
         use super::*;

Diff for: src/client/mod.rs

@@ -92,7 +92,7 @@ use http::uri::Scheme;
 use body::{Body, Payload};
 use common::Exec;
 use common::lazy as hyper_lazy;
-use self::connect::{Connect, Destination};
+use self::connect::{Connect, Connected, Destination};
 use self::pool::{Pool, Poolable, Reservation};
 
 #[cfg(feature = "runtime")] pub use self::connect::HttpConnector;
@@ -304,7 +304,7 @@ where C: Connect + Sync + 'static,
                                 })
                                 .map(move |tx| {
                                     pool.pooled(connecting, PoolClient {
-                                        is_proxied: connected.is_proxied,
+                                        conn_info: connected,
                                         tx: match ver {
                                             Ver::Http1 => PoolTx::Http1(tx),
                                             Ver::Http2 => PoolTx::Http2(tx.into_http2()),
@@ -387,7 +387,7 @@ where C: Connect + Sync + 'static,
                 // CONNECT always sends origin-form, so check it first...
                 if req.method() == &Method::CONNECT {
                     authority_form(req.uri_mut());
-                } else if pooled.is_proxied {
+                } else if pooled.conn_info.is_proxied {
                     absolute_form(req.uri_mut());
                 } else {
                     origin_form(req.uri_mut());
@@ -401,6 +401,14 @@ where C: Connect + Sync + 'static,
 
             let fut = pooled.send_request_retryable(req);
 
+            let extra_info = pooled.conn_info.extra.clone();
+            let fut = fut.map(move |mut res| {
+                if let Some(extra) = extra_info {
+                    extra.set(&mut res);
+                }
+                res
+            });
+
             // As of [email protected], there is a race condition in the mpsc
             // channel, such that sending when the receiver is closing can
             // result in the message being stuck inside the queue. It won't
@@ -584,7 +592,7 @@ where
 }
 
 struct PoolClient<B> {
-    is_proxied: bool,
+    conn_info: Connected,
     tx: PoolTx<B>,
 }
 
@@ -644,17 +652,17 @@ where
         match self.tx {
             PoolTx::Http1(tx) => {
                 Reservation::Unique(PoolClient {
-                    is_proxied: self.is_proxied,
+                    conn_info: self.conn_info,
                     tx: PoolTx::Http1(tx),
                 })
             },
             PoolTx::Http2(tx) => {
                 let b = PoolClient {
-                    is_proxied: self.is_proxied,
+                    conn_info: self.conn_info.clone(),
                     tx: PoolTx::Http2(tx.clone()),
                 };
                 let a = PoolClient {
-                    is_proxied: self.is_proxied,
+                    conn_info: self.conn_info,
                     tx: PoolTx::Http2(tx),
                 };
                 Reservation::Shared(a, b)

Diff for: tests/client.rs

@@ -274,7 +274,17 @@ macro_rules! test {
 
         let rx = rx.expect("thread panicked");
 
-        rt.block_on(res.join(rx).map(|r| r.0))
+        rt.block_on(res.join(rx).map(|r| r.0)).map(move |mut resp| {
+            // Always check that HttpConnector has set the "extra" info...
+            let extra = resp
+                .extensions_mut()
+                .remove::<::hyper::client::connect::HttpInfo>()
+                .expect("HttpConnector should set HttpInfo");
+
+            assert_eq!(extra.remote_addr(), addr, "HttpInfo should have server addr");
+
+            resp
+        })
     });
 }