blob: 3e17efec61bdccf539e06793b79da774959f3025 [file] [log] [blame]
* Copyright 2017 gRPC authors.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* See the License for the specific language governing permissions and
* limitations under the License.
package grpc
import (
var (
// errDisabled indicates that proxy is disabled for the address.
errDisabled = errors.New("proxy is disabled for the address")
// The following variable will be overwritten in the tests.
httpProxyFromEnvironment = http.ProxyFromEnvironment
func mapAddress(ctx context.Context, address string) (string, error) {
req := &http.Request{
URL: &url.URL{
Scheme: "https",
Host: address,
url, err := httpProxyFromEnvironment(req)
if err != nil {
return "", err
if url == nil {
return "", errDisabled
return url.Host, nil
// To read a response from a net.Conn, http.ReadResponse() takes a bufio.Reader.
// It's possible that this reader reads more than what's need for the response and stores
// those bytes in the buffer.
// bufConn wraps the original net.Conn and the bufio.Reader to make sure we don't lose the
// bytes in the buffer.
type bufConn struct {
r io.Reader
func (c *bufConn) Read(b []byte) (int, error) {
return c.r.Read(b)
func doHTTPConnectHandshake(ctx context.Context, conn net.Conn, addr string) (_ net.Conn, err error) {
defer func() {
if err != nil {
req := (&http.Request{
Method: http.MethodConnect,
URL: &url.URL{Host: addr},
Header: map[string][]string{"User-Agent": {grpcUA}},
req = req.WithContext(ctx)
if err := req.Write(conn); err != nil {
return nil, fmt.Errorf("failed to write the HTTP request: %v", err)
r := bufio.NewReader(conn)
resp, err := http.ReadResponse(r, req)
if err != nil {
return nil, fmt.Errorf("reading server HTTP response: %v", err)
defer resp.Body.Close()
if resp.StatusCode != http.StatusOK {
dump, err := httputil.DumpResponse(resp, true)
if err != nil {
return nil, fmt.Errorf("failed to do connect handshake, status code: %s", resp.Status)
return nil, fmt.Errorf("failed to do connect handshake, response: %q", dump)
return &bufConn{Conn: conn, r: r}, nil
// newProxyDialer returns a dialer that connects to proxy first if necessary.
// The returned dialer checks if a proxy is necessary, dial to the proxy with the
// provided dialer, does HTTP CONNECT handshake and returns the connection.
func newProxyDialer(dialer func(context.Context, string) (net.Conn, error)) func(context.Context, string) (net.Conn, error) {
return func(ctx context.Context, addr string) (conn net.Conn, err error) {
var skipHandshake bool
newAddr, err := mapAddress(ctx, addr)
if err != nil {
if err != errDisabled {
return nil, err
skipHandshake = true
newAddr = addr
conn, err = dialer(ctx, newAddr)
if err != nil {
if !skipHandshake {
conn, err = doHTTPConnectHandshake(ctx, conn, addr)