support http proxy correctly

client.go

@@ -17,6 +17,8 @@ import (
 	"net/url"
 	"strings"
 	"time"
+
+	"golang.org/x/net/proxy"
 )
 
 // ErrBadHandshake is returned when the server response to opening handshake is
@@ -281,11 +283,30 @@ func (d *Dialer) DialContext(ctx context.Context, urlStr string, requestHeader h
 		if err != nil {
 			return nil, nil, err
 		}
-		if proxyURL != nil {
+		switch {
-			netDial, err = proxyFromURL(proxyURL, netDial)
+		case proxyURL == nil:
+			// Do nothing. Not using a proxy.
+		case u.Scheme == "http":
+			if pa := proxyAuth(proxyURL.User); pa != "" {
+				req.Header.Set("Proxy-Authorization", pa)
+			}
+			netDial = func(ctx context.Context, network, addr string) (net.Conn, error) {
+				return (&net.Dialer{}).DialContext(ctx, network, proxyURL.Host)
+			}
+		case u.Scheme == "https":
+			netDial = (&httpsProxyDialer{proxyURL: proxyURL, forwardDial: netDial}).DialContext
+		default:
+			dialer, err := proxy.FromURL(proxyURL, netDial)
 			if err != nil {
 				return nil, nil, err
 			}
+			if d, ok := dialer.(proxy.ContextDialer); ok {
+				netDial = d.DialContext
+			} else {
+				netDial = func(ctx context.Context, network, addr string) (net.Conn, error) {
+					return dialer.Dial(network, addr)
+				}
+			}
 		}
 	}
 

proxy.go

@@ -14,8 +14,6 @@ import (
 	"net/http"
 	"net/url"
 	"strings"
-
-	"golang.org/x/net/proxy"
 )
 
 type netDialerFunc func(ctx context.Context, network, addr string) (net.Conn, error)
@@ -28,28 +26,12 @@ func (fn netDialerFunc) DialContext(ctx context.Context, network, addr string) (
 	return fn(ctx, network, addr)
 }
 
-func proxyFromURL(proxyURL *url.URL, forwardDial netDialerFunc) (netDialerFunc, error) {
+type httpsProxyDialer struct {
-	if proxyURL.Scheme == "http" {
-		return (&httpProxyDialer{proxyURL: proxyURL, forwardDial: forwardDial}).DialContext, nil
-	}
-	dialer, err := proxy.FromURL(proxyURL, forwardDial)
-	if err != nil {
-		return nil, err
-	}
-	if d, ok := dialer.(proxy.ContextDialer); ok {
-		return d.DialContext, nil
-	}
-	return func(ctx context.Context, net, addr string) (net.Conn, error) {
-		return dialer.Dial(net, addr)
-	}, nil
-}
-
-type httpProxyDialer struct {
 	proxyURL    *url.URL
 	forwardDial netDialerFunc
 }
 
-func (hpd *httpProxyDialer) DialContext(ctx context.Context, network string, addr string) (net.Conn, error) {
+func (hpd *httpsProxyDialer) DialContext(ctx context.Context, network string, addr string) (net.Conn, error) {
 	hostPort, _ := hostPortNoPort(hpd.proxyURL)
 	conn, err := hpd.forwardDial(ctx, network, hostPort)
 	if err != nil {
@@ -57,12 +39,8 @@ func (hpd *httpProxyDialer) DialContext(ctx context.Context, network string, add
 	}
 
 	connectHeader := make(http.Header)
-	if user := hpd.proxyURL.User; user != nil {
+	if pa := proxyAuth(hpd.proxyURL.User); pa != "" {
-		proxyUser := user.Username()
+		connectHeader.Set("Proxy-Authorization", pa)
-		if proxyPassword, passwordSet := user.Password(); passwordSet {
-			credential := base64.StdEncoding.EncodeToString([]byte(proxyUser + ":" + proxyPassword))
-			connectHeader.Set("Proxy-Authorization", "Basic "+credential)
-		}
 	}
 
 	connectReq := &http.Request{
@@ -103,3 +81,13 @@ func (hpd *httpProxyDialer) DialContext(ctx context.Context, network string, add
 	}
 	return conn, nil
 }
+
+func proxyAuth(user *url.Userinfo) string {
+	if user != nil {
+		proxyUser := user.Username()
+		if proxyPassword, passwordSet := user.Password(); passwordSet {
+			return "Basic " + base64.StdEncoding.EncodeToString([]byte(proxyUser+":"+proxyPassword))
+		}
+	}
+	return ""
+}