feat(client): support local bind for HttpConnector

Add `set_local_address` to the `HttpConnector`.
This configures the client to bind the socket to a local address of
the host before it connects to the destination. This is useful on
hosts which have multiple network interfaces, to ensure the request is
issued over a specific interface.

Closes hyperium#1498

Cargo.toml

@@ -57,6 +57,11 @@ runtime = [
     "tokio-tcp",
 ]
 
+[[example]]
+name = "bound_client"
+path = "examples/bound_client.rs"
+required-features = ["runtime"]
+
 [[example]]
 name = "client"
 path = "examples/client.rs"

examples/bound_client.rs

@@ -0,0 +1,56 @@
+#![deny(warnings)]
+extern crate hyper;
+extern crate pretty_env_logger;
+
+use std::env;
+use std::net::IpAddr;
+use std::io::{self, Write};
+
+use hyper::{Body, Client, Request};
+use hyper::rt::{self, Future, Stream};
+use hyper::client::connect::HttpConnector;
+
+fn main() {
+    pretty_env_logger::init();
+
+    let url = match env::args().nth(1) {
+        Some(url) => url,
+        None => {
+            println!("Usage: client <url> [<bind_addr>]");
+            return;
+        }
+    };
+
+    let url = url.parse::<hyper::Uri>().unwrap();
+    if url.scheme_part().map(|s| s.as_ref()) != Some("http") {
+        println!("This example only works with 'http' URLs.");
+        return;
+    }
+
+    let bind_addr = env::args().nth(2);
+
+    let bind_addr: Option<IpAddr> = bind_addr.map(|s| s.parse::<IpAddr>().unwrap());
+
+    rt::run(rt::lazy(move || {
+        let mut connector = HttpConnector::new(4);
+        connector.set_local_address(bind_addr);
+        let client = Client::builder().build(connector);
+
+        let mut req = Request::new(Body::empty());
+        *req.uri_mut() = url;
+
+        client.request(req).and_then(|res| {
+            println!("Response: {}", res.status());
+            println!("Headers: {:#?}", res.headers());
+
+            res.into_body().for_each(|chunk| {
+                io::stdout().write_all(&chunk)
+                    .map_err(|e| panic!("example expects stdout is open, error={}", e))
+            })
+        }).map(|_| {
+            println!("\n\nDone.");
+        }).map_err(|err| {
+            eprintln!("Error {}", err);
+        })
+    }));
+}

src/client/connect.rs

@@ -6,6 +6,7 @@
 //!   establishes connections over TCP.
 //! - The [`Connect`](Connect) trait and related types to build custom connectors.
 use std::error::Error as StdError;
+use std::borrow::Cow;
 
 use futures::Future;
 use http::Uri;
@@ -128,7 +129,7 @@ mod http {
     use std::fmt;
     use std::io;
     use std::mem;
-    use std::net::SocketAddr;
+    use std::net::{IpAddr, SocketAddr};
     use std::sync::Arc;
     use std::time::Duration;
 
@@ -146,30 +147,35 @@ mod http {
     use self::http_connector::HttpConnectorBlockingTask;
 
 
-    fn connect(addr: &SocketAddr, handle: &Option<Handle>) -> io::Result<ConnectFuture> {
-        if let Some(ref handle) = *handle {
-            let builder = match addr {
-                &SocketAddr::V4(_) => TcpBuilder::new_v4()?,
-                &SocketAddr::V6(_) => TcpBuilder::new_v6()?,
+    fn connect(addr: &SocketAddr, local_addr: &Option<IpAddr>, handle: &Option<Handle>) -> io::Result<ConnectFuture> {
+        let builder = match addr {
+            &SocketAddr::V4(_) => TcpBuilder::new_v4()?,
+            &SocketAddr::V6(_) => TcpBuilder::new_v6()?,
+        };
+
+        if let Some(ref local_addr) = *local_addr {
+            // Caller has requested this socket be bound before calling connect
+            builder.bind(SocketAddr::new(local_addr.clone(), 0))?;
+        }
+        else if cfg!(windows) {
+            // Windows requires a socket be bound before calling connect
+            let any: SocketAddr = match addr {
+                &SocketAddr::V4(_) => {
+                    ([0, 0, 0, 0], 0).into()
+                },
+                &SocketAddr::V6(_) => {
+                    ([0, 0, 0, 0, 0, 0, 0, 0], 0).into()
+                }
             };
+            builder.bind(any)?;
+        }
 
-            if cfg!(windows) {
-                // Windows requires a socket be bound before calling connect
-                let any: SocketAddr = match addr {
-                    &SocketAddr::V4(_) => {
-                        ([0, 0, 0, 0], 0).into()
-                    },
-                    &SocketAddr::V6(_) => {
-                        ([0, 0, 0, 0, 0, 0, 0, 0], 0).into()
-                    }
-                };
-                builder.bind(any)?;
-            }
+        let handle = match *handle {
+            Some(ref handle) => Cow::Borrowed(handle),
+            None => Cow::Owned(Handle::current()),
+        };
 
-            Ok(TcpStream::connect_std(builder.to_tcp_stream()?, addr, handle))
-        } else {
-            Ok(TcpStream::connect(addr))
-        }
+        Ok(TcpStream::connect_std(builder.to_tcp_stream()?, addr, &handle))
     }
 
     /// A connector for the `http` scheme.
@@ -182,6 +188,7 @@ mod http {
         handle: Option<Handle>,
         keep_alive_timeout: Option<Duration>,
         nodelay: bool,
+        local_address: Option<IpAddr>,
     }
 
     impl HttpConnector {
@@ -218,6 +225,7 @@ mod http {
                 handle,
                 keep_alive_timeout: None,
                 nodelay: false,
+                local_address: None,
             }
         }
 
@@ -246,6 +254,16 @@ mod http {
         pub fn set_nodelay(&mut self, nodelay: bool) {
             self.nodelay = nodelay;
         }
+
+        /// Set that all sockets are bound to the configured address before connection.
+        ///
+        /// If `None`, the sockets will not be bound.
+        ///
+        /// Default is `None`.
+        #[inline]
+        pub fn set_local_address(&mut self, addr: Option<IpAddr>) {
+            self.local_address = addr;
+        }
     }
 
     impl fmt::Debug for HttpConnector {
@@ -287,7 +305,7 @@ mod http {
             };
 
             HttpConnecting {
-                state: State::Lazy(self.executor.clone(), host.into(), port),
+                state: State::Lazy(self.executor.clone(), host.into(), port, self.local_address),
                 handle: self.handle.clone(),
                 keep_alive_timeout: self.keep_alive_timeout,
                 nodelay: self.nodelay,
@@ -337,8 +355,8 @@ mod http {
     }
 
     enum State {
-        Lazy(HttpConnectExecutor, String, u16),
-        Resolving(oneshot::SpawnHandle<dns::IpAddrs, io::Error>),
+        Lazy(HttpConnectExecutor, String, u16, Option<IpAddr>),
+        Resolving(oneshot::SpawnHandle<dns::IpAddrs, io::Error>, Option<IpAddr>),
         Connecting(ConnectingTcp),
         Error(Option<io::Error>),
     }
@@ -351,26 +369,28 @@ mod http {
             loop {
                 let state;
                 match self.state {
-                    State::Lazy(ref executor, ref mut host, port) => {
+                    State::Lazy(ref executor, ref mut host, port, local_addr) => {
                         // If the host is already an IP addr (v4 or v6),
                         // skip resolving the dns and start connecting right away.
                         if let Some(addrs) = dns::IpAddrs::try_parse(host, port) {
                             state = State::Connecting(ConnectingTcp {
                                 addrs: addrs,
+                                local_addr: local_addr,
                                 current: None
                             })
                         } else {
                             let host = mem::replace(host, String::new());
                             let work = dns::Work::new(host, port);
-                            state = State::Resolving(oneshot::spawn(work, executor));
+                            state = State::Resolving(oneshot::spawn(work, executor), local_addr);
                         }
                     },
-                    State::Resolving(ref mut future) => {
+                    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,
                                 })
                             }
@@ -402,6 +422,7 @@ mod http {
 
     struct ConnectingTcp {
         addrs: dns::IpAddrs,
+        local_addr: Option<IpAddr>,
         current: Option<ConnectFuture>,
     }
 
@@ -418,14 +439,14 @@ mod http {
                             err = Some(e);
                             if let Some(addr) = self.addrs.next() {
                                 debug!("connecting to {}", addr);
-                                *current = connect(&addr, handle)?;
+                                *current = connect(&addr, &self.local_addr, handle)?;
                                 continue;
                             }
                         }
                     }
                 } else if let Some(addr) = self.addrs.next() {
                     debug!("connecting to {}", addr);
-                    self.current = Some(connect(&addr, handle)?);
+                    self.current = Some(connect(&addr, &self.local_addr, handle)?);
                     continue;
                 }