http: let Transport use a custom net.Dial function

Permits the use of SOCKS proxy dialer with
the transport.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/4536091

diff --git a/src/pkg/http/transport.go b/src/pkg/http/transport.go
index 2b5e5a4250e0cc4e171f223039474ccd2b52524c..c907d85fd2a5f9dbc490d17fe79d1ef72bd56a47 100644 (file)
--- a/src/pkg/http/transport.go
+++ b/src/pkg/http/transport.go
@@ -42,12 +42,17 @@ type Transport struct {
        // TODO: tunable on timeout on cached connections
        // TODO: optional pipelining
 
-       // Proxy optionally specifies a function to return a proxy for
-       // a given Request. If the function returns a non-nil error,
-       // the request is aborted with the provided error. If Proxy is
-       // nil or returns a nil *URL, no proxy is used.
+       // Proxy specifies a function to return a proxy for a given
+       // Request. If the function returns a non-nil error, the
+       // request is aborted with the provided error.
+       // If Proxy is nil or returns a nil *URL, no proxy is used.
        Proxy func(*Request) (*URL, os.Error)
 
+       // Dial specifies the dial function for creating TCP
+       // connections.
+       // If Dial is nil, net.Dial is used.
+       Dial func(net, addr string) (c net.Conn, err os.Error)
+
        DisableKeepAlives  bool
        DisableCompression bool
 
@@ -255,6 +260,13 @@ func (t *Transport) getIdleConn(cm *connectMethod) (pconn *persistConn) {
        return
 }
 
+func (t *Transport) dial(network, addr string) (c net.Conn, err os.Error) {
+       if t.Dial != nil {
+               return t.Dial(network, addr)
+       }
+       return net.Dial(network, addr)
+}
+
 // getConn dials and creates a new persistConn to the target as
 // specified in the connectMethod.  This includes doing a proxy CONNECT
 // and/or setting up TLS.  If this doesn't return an error, the persistConn
@@ -264,7 +276,7 @@ func (t *Transport) getConn(cm *connectMethod) (*persistConn, os.Error) {
                return pc, nil
        }
 
-       conn, err := net.Dial("tcp", cm.addr())
+       conn, err := t.dial("tcp", cm.addr())
        if err != nil {
                if cm.proxyURL != nil {
                        err = fmt.Errorf("http: error connecting to proxy %s: %v", cm.proxyURL, err)