Add set_nodelay and set_keepalive (#123)

These additions are similar to those in 271e24d, which were then
removed during the transition to futures and tokio in 5bf6560.

src/relay/tcprelay/server.rs

@@ -139,6 +139,14 @@ fn handle_client(server_cfg: Arc<ServerConfig>,
                  config: Arc<Config>,
                  socket: TcpStream)
                  -> impl Future<Item = (), Error = ()> + Send {
+    if let Err(err) = socket.set_keepalive(*server_cfg.timeout()) {
+        error!("Failed to set keep alive: {:?}", err);
+    }
+
+    if let Err(err) = socket.set_nodelay(true) {
+        error!("Failed to set no delay: {:?}", err);
+    }
+
     futures::lazy(move || match socket.peer_addr() {
                       Ok(addr) => Ok((socket, addr)),
                       Err(err) => {

src/relay/tcprelay/socks5_local.rs

@@ -92,6 +92,14 @@ fn handle_socks5_client(config: Arc<Config>,
                         conf: Arc<ServerConfig>,
                         udp_conf: UdpConfig)
                         -> io::Result<()> {
+    if let Err(err) = s.set_keepalive(*conf.timeout()) {
+        error!("Failed to set keep alive: {:?}", err);
+    }
+
+    if let Err(err) = s.set_nodelay(true) {
+        error!("Failed to set no delay: {:?}", err);
+    }
+
     let client_addr = s.peer_addr()?;
     let cloned_client_addr = client_addr;
     let fut = futures::lazy(|| Ok(s.split()))