add/update deps

2026-06-07 13:33:32 +02:00 · 2017-11-04 15:25:51 -07:00
parent 84bd64a188
commit a2e36e808a
61 changed files with 12394 additions and 1 deletions
@@ -0,0 +1,10 @@
+# Treat all files in this repo as binary, with no git magic updating
+# line endings. Windows users contributing to Go will need to use a
+# modern version of git and editors capable of LF line endings.
+#
+# We'll prevent accidental CRLF line endings from entering the repo
+# via the git-review gofmt checks.
+#
+# See golang.org/issue/9281
+
+* -text
@@ -0,0 +1,2 @@
+# Add no patterns to .hgignore except for files generated by the build.
+last-change
@@ -0,0 +1,3 @@
+# This source code refers to The Go Authors for copyright purposes.
+# The master list of authors is in the main Go distribution,
+# visible at http://tip.golang.org/AUTHORS.
@@ -0,0 +1,31 @@
+# Contributing to Go
+
+Go is an open source project.
+
+It is the work of hundreds of contributors. We appreciate your help!
+
+
+## Filing issues
+
+When [filing an issue](https://golang.org/issue/new), make sure to answer these five questions:
+
+1. What version of Go are you using (`go version`)?
+2. What operating system and processor architecture are you using?
+3. What did you do?
+4. What did you expect to see?
+5. What did you see instead?
+
+General questions should go to the [golang-nuts mailing list](https://groups.google.com/group/golang-nuts) instead of the issue tracker.
+The gophers there will answer or ask you to file an issue if you've tripped over a bug.
+
+## Contributing code
+
+Please read the [Contribution Guidelines](https://golang.org/doc/contribute.html)
+before sending patches.
+
+**We do not accept GitHub pull requests**
+(we use [Gerrit](https://code.google.com/p/gerrit/) instead for code review).
+
+Unless otherwise noted, the Go source files are distributed under
+the BSD-style license found in the LICENSE file.
+
@@ -0,0 +1,3 @@
+# This source code was written by the Go contributors.
+# The master list of contributors is in the main Go distribution,
+# visible at http://tip.golang.org/CONTRIBUTORS.
@@ -0,0 +1,27 @@
+Copyright (c) 2009 The Go Authors. All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+   * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+   * Redistributions in binary form must reproduce the above
+copyright notice, this list of conditions and the following disclaimer
+in the documentation and/or other materials provided with the
+distribution.
+   * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
@@ -0,0 +1,22 @@
+Additional IP Rights Grant (Patents)
+
+"This implementation" means the copyrightable works distributed by
+Google as part of the Go project.
+
+Google hereby grants to You a perpetual, worldwide, non-exclusive,
+no-charge, royalty-free, irrevocable (except as stated in this section)
+patent license to make, have made, use, offer to sell, sell, import,
+transfer and otherwise run, modify and propagate the contents of this
+implementation of Go, where such license applies only to those patent
+claims, both currently owned or controlled by Google and acquired in
+the future, licensable by Google that are necessarily infringed by this
+implementation of Go.  This grant does not include claims that would be
+infringed only as a consequence of further modification of this
+implementation.  If you or your agent or exclusive licensee institute or
+order or agree to the institution of patent litigation against any
+entity (including a cross-claim or counterclaim in a lawsuit) alleging
+that this implementation of Go or any code incorporated within this
+implementation of Go constitutes direct or contributory patent
+infringement, or inducement of patent infringement, then any patent
+rights granted to you under this License for this implementation of Go
+shall terminate as of the date such litigation is filed.
@@ -0,0 +1,16 @@
+# Go Networking
+
+This repository holds supplementary Go networking libraries.
+
+## Download/Install
+
+The easiest way to install is to run `go get -u golang.org/x/net`. You can
+also manually git clone the repository to `$GOPATH/src/golang.org/x/net`.
+
+## Report Issues / Send Patches
+
+This repository uses Gerrit for code changes. To learn how to submit
+changes to this repository, see https://golang.org/doc/contribute.html.
+The main issue tracker for the net repository is located at
+https://github.com/golang/go/issues. Prefix your issue with "x/net:" in the
+subject line, so it is easy to find.
@@ -0,0 +1 @@
+issuerepo: golang/go
@@ -0,0 +1,18 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package proxy
+
+import (
+	"net"
+)
+
+type direct struct{}
+
+// Direct is a direct proxy: one that makes network connections directly.
+var Direct = direct{}
+
+func (direct) Dial(network, addr string) (net.Conn, error) {
+	return net.Dial(network, addr)
+}
@@ -0,0 +1,140 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package proxy
+
+import (
+	"net"
+	"strings"
+)
+
+// A PerHost directs connections to a default Dialer unless the host name
+// requested matches one of a number of exceptions.
+type PerHost struct {
+	def, bypass Dialer
+
+	bypassNetworks []*net.IPNet
+	bypassIPs      []net.IP
+	bypassZones    []string
+	bypassHosts    []string
+}
+
+// NewPerHost returns a PerHost Dialer that directs connections to either
+// defaultDialer or bypass, depending on whether the connection matches one of
+// the configured rules.
+func NewPerHost(defaultDialer, bypass Dialer) *PerHost {
+	return &PerHost{
+		def:    defaultDialer,
+		bypass: bypass,
+	}
+}
+
+// Dial connects to the address addr on the given network through either
+// defaultDialer or bypass.
+func (p *PerHost) Dial(network, addr string) (c net.Conn, err error) {
+	host, _, err := net.SplitHostPort(addr)
+	if err != nil {
+		return nil, err
+	}
+
+	return p.dialerForRequest(host).Dial(network, addr)
+}
+
+func (p *PerHost) dialerForRequest(host string) Dialer {
+	if ip := net.ParseIP(host); ip != nil {
+		for _, net := range p.bypassNetworks {
+			if net.Contains(ip) {
+				return p.bypass
+			}
+		}
+		for _, bypassIP := range p.bypassIPs {
+			if bypassIP.Equal(ip) {
+				return p.bypass
+			}
+		}
+		return p.def
+	}
+
+	for _, zone := range p.bypassZones {
+		if strings.HasSuffix(host, zone) {
+			return p.bypass
+		}
+		if host == zone[1:] {
+			// For a zone ".example.com", we match "example.com"
+			// too.
+			return p.bypass
+		}
+	}
+	for _, bypassHost := range p.bypassHosts {
+		if bypassHost == host {
+			return p.bypass
+		}
+	}
+	return p.def
+}
+
+// AddFromString parses a string that contains comma-separated values
+// specifying hosts that should use the bypass proxy. Each value is either an
+// IP address, a CIDR range, a zone (*.example.com) or a host name
+// (localhost). A best effort is made to parse the string and errors are
+// ignored.
+func (p *PerHost) AddFromString(s string) {
+	hosts := strings.Split(s, ",")
+	for _, host := range hosts {
+		host = strings.TrimSpace(host)
+		if len(host) == 0 {
+			continue
+		}
+		if strings.Contains(host, "/") {
+			// We assume that it's a CIDR address like 127.0.0.0/8
+			if _, net, err := net.ParseCIDR(host); err == nil {
+				p.AddNetwork(net)
+			}
+			continue
+		}
+		if ip := net.ParseIP(host); ip != nil {
+			p.AddIP(ip)
+			continue
+		}
+		if strings.HasPrefix(host, "*.") {
+			p.AddZone(host[1:])
+			continue
+		}
+		p.AddHost(host)
+	}
+}
+
+// AddIP specifies an IP address that will use the bypass proxy. Note that
+// this will only take effect if a literal IP address is dialed. A connection
+// to a named host will never match an IP.
+func (p *PerHost) AddIP(ip net.IP) {
+	p.bypassIPs = append(p.bypassIPs, ip)
+}
+
+// AddNetwork specifies an IP range that will use the bypass proxy. Note that
+// this will only take effect if a literal IP address is dialed. A connection
+// to a named host will never match.
+func (p *PerHost) AddNetwork(net *net.IPNet) {
+	p.bypassNetworks = append(p.bypassNetworks, net)
+}
+
+// AddZone specifies a DNS suffix that will use the bypass proxy. A zone of
+// "example.com" matches "example.com" and all of its subdomains.
+func (p *PerHost) AddZone(zone string) {
+	if strings.HasSuffix(zone, ".") {
+		zone = zone[:len(zone)-1]
+	}
+	if !strings.HasPrefix(zone, ".") {
+		zone = "." + zone
+	}
+	p.bypassZones = append(p.bypassZones, zone)
+}
+
+// AddHost specifies a host name that will use the bypass proxy.
+func (p *PerHost) AddHost(host string) {
+	if strings.HasSuffix(host, ".") {
+		host = host[:len(host)-1]
+	}
+	p.bypassHosts = append(p.bypassHosts, host)
+}
@@ -0,0 +1,55 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package proxy
+
+import (
+	"errors"
+	"net"
+	"reflect"
+	"testing"
+)
+
+type recordingProxy struct {
+	addrs []string
+}
+
+func (r *recordingProxy) Dial(network, addr string) (net.Conn, error) {
+	r.addrs = append(r.addrs, addr)
+	return nil, errors.New("recordingProxy")
+}
+
+func TestPerHost(t *testing.T) {
+	var def, bypass recordingProxy
+	perHost := NewPerHost(&def, &bypass)
+	perHost.AddFromString("localhost,*.zone,127.0.0.1,10.0.0.1/8,1000::/16")
+
+	expectedDef := []string{
+		"example.com:123",
+		"1.2.3.4:123",
+		"[1001::]:123",
+	}
+	expectedBypass := []string{
+		"localhost:123",
+		"zone:123",
+		"foo.zone:123",
+		"127.0.0.1:123",
+		"10.1.2.3:123",
+		"[1000::]:123",
+	}
+
+	for _, addr := range expectedDef {
+		perHost.Dial("tcp", addr)
+	}
+	for _, addr := range expectedBypass {
+		perHost.Dial("tcp", addr)
+	}
+
+	if !reflect.DeepEqual(expectedDef, def.addrs) {
+		t.Errorf("Hosts which went to the default proxy didn't match. Got %v, want %v", def.addrs, expectedDef)
+	}
+	if !reflect.DeepEqual(expectedBypass, bypass.addrs) {
+		t.Errorf("Hosts which went to the bypass proxy didn't match. Got %v, want %v", bypass.addrs, expectedBypass)
+	}
+}
@@ -0,0 +1,134 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Package proxy provides support for a variety of protocols to proxy network
+// data.
+package proxy // import "golang.org/x/net/proxy"
+
+import (
+	"errors"
+	"net"
+	"net/url"
+	"os"
+	"sync"
+)
+
+// A Dialer is a means to establish a connection.
+type Dialer interface {
+	// Dial connects to the given address via the proxy.
+	Dial(network, addr string) (c net.Conn, err error)
+}
+
+// Auth contains authentication parameters that specific Dialers may require.
+type Auth struct {
+	User, Password string
+}
+
+// FromEnvironment returns the dialer specified by the proxy related variables in
+// the environment.
+func FromEnvironment() Dialer {
+	allProxy := allProxyEnv.Get()
+	if len(allProxy) == 0 {
+		return Direct
+	}
+
+	proxyURL, err := url.Parse(allProxy)
+	if err != nil {
+		return Direct
+	}
+	proxy, err := FromURL(proxyURL, Direct)
+	if err != nil {
+		return Direct
+	}
+
+	noProxy := noProxyEnv.Get()
+	if len(noProxy) == 0 {
+		return proxy
+	}
+
+	perHost := NewPerHost(proxy, Direct)
+	perHost.AddFromString(noProxy)
+	return perHost
+}
+
+// proxySchemes is a map from URL schemes to a function that creates a Dialer
+// from a URL with such a scheme.
+var proxySchemes map[string]func(*url.URL, Dialer) (Dialer, error)
+
+// RegisterDialerType takes a URL scheme and a function to generate Dialers from
+// a URL with that scheme and a forwarding Dialer. Registered schemes are used
+// by FromURL.
+func RegisterDialerType(scheme string, f func(*url.URL, Dialer) (Dialer, error)) {
+	if proxySchemes == nil {
+		proxySchemes = make(map[string]func(*url.URL, Dialer) (Dialer, error))
+	}
+	proxySchemes[scheme] = f
+}
+
+// FromURL returns a Dialer given a URL specification and an underlying
+// Dialer for it to make network requests.
+func FromURL(u *url.URL, forward Dialer) (Dialer, error) {
+	var auth *Auth
+	if u.User != nil {
+		auth = new(Auth)
+		auth.User = u.User.Username()
+		if p, ok := u.User.Password(); ok {
+			auth.Password = p
+		}
+	}
+
+	switch u.Scheme {
+	case "socks5":
+		return SOCKS5("tcp", u.Host, auth, forward)
+	}
+
+	// If the scheme doesn't match any of the built-in schemes, see if it
+	// was registered by another package.
+	if proxySchemes != nil {
+		if f, ok := proxySchemes[u.Scheme]; ok {
+			return f(u, forward)
+		}
+	}
+
+	return nil, errors.New("proxy: unknown scheme: " + u.Scheme)
+}
+
+var (
+	allProxyEnv = &envOnce{
+		names: []string{"ALL_PROXY", "all_proxy"},
+	}
+	noProxyEnv = &envOnce{
+		names: []string{"NO_PROXY", "no_proxy"},
+	}
+)
+
+// envOnce looks up an environment variable (optionally by multiple
+// names) once. It mitigates expensive lookups on some platforms
+// (e.g. Windows).
+// (Borrowed from net/http/transport.go)
+type envOnce struct {
+	names []string
+	once  sync.Once
+	val   string
+}
+
+func (e *envOnce) Get() string {
+	e.once.Do(e.init)
+	return e.val
+}
+
+func (e *envOnce) init() {
+	for _, n := range e.names {
+		e.val = os.Getenv(n)
+		if e.val != "" {
+			return
+		}
+	}
+}
+
+// reset is used by tests
+func (e *envOnce) reset() {
+	e.once = sync.Once{}
+	e.val = ""
+}
@@ -0,0 +1,215 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package proxy
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"net"
+	"net/url"
+	"os"
+	"strconv"
+	"strings"
+	"sync"
+	"testing"
+)
+
+type proxyFromEnvTest struct {
+	allProxyEnv string
+	noProxyEnv  string
+	wantTypeOf  Dialer
+}
+
+func (t proxyFromEnvTest) String() string {
+	var buf bytes.Buffer
+	space := func() {
+		if buf.Len() > 0 {
+			buf.WriteByte(' ')
+		}
+	}
+	if t.allProxyEnv != "" {
+		fmt.Fprintf(&buf, "all_proxy=%q", t.allProxyEnv)
+	}
+	if t.noProxyEnv != "" {
+		space()
+		fmt.Fprintf(&buf, "no_proxy=%q", t.noProxyEnv)
+	}
+	return strings.TrimSpace(buf.String())
+}
+
+func TestFromEnvironment(t *testing.T) {
+	ResetProxyEnv()
+
+	type dummyDialer struct {
+		direct
+	}
+
+	RegisterDialerType("irc", func(_ *url.URL, _ Dialer) (Dialer, error) {
+		return dummyDialer{}, nil
+	})
+
+	proxyFromEnvTests := []proxyFromEnvTest{
+		{allProxyEnv: "127.0.0.1:8080", noProxyEnv: "localhost, 127.0.0.1", wantTypeOf: direct{}},
+		{allProxyEnv: "ftp://example.com:8000", noProxyEnv: "localhost, 127.0.0.1", wantTypeOf: direct{}},
+		{allProxyEnv: "socks5://example.com:8080", noProxyEnv: "localhost, 127.0.0.1", wantTypeOf: &PerHost{}},
+		{allProxyEnv: "irc://example.com:8000", wantTypeOf: dummyDialer{}},
+		{noProxyEnv: "localhost, 127.0.0.1", wantTypeOf: direct{}},
+		{wantTypeOf: direct{}},
+	}
+
+	for _, tt := range proxyFromEnvTests {
+		os.Setenv("ALL_PROXY", tt.allProxyEnv)
+		os.Setenv("NO_PROXY", tt.noProxyEnv)
+		ResetCachedEnvironment()
+
+		d := FromEnvironment()
+		if got, want := fmt.Sprintf("%T", d), fmt.Sprintf("%T", tt.wantTypeOf); got != want {
+			t.Errorf("%v: got type = %T, want %T", tt, d, tt.wantTypeOf)
+		}
+	}
+}
+
+func TestFromURL(t *testing.T) {
+	endSystem, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("net.Listen failed: %v", err)
+	}
+	defer endSystem.Close()
+	gateway, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("net.Listen failed: %v", err)
+	}
+	defer gateway.Close()
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go socks5Gateway(t, gateway, endSystem, socks5Domain, &wg)
+
+	url, err := url.Parse("socks5://user:password@" + gateway.Addr().String())
+	if err != nil {
+		t.Fatalf("url.Parse failed: %v", err)
+	}
+	proxy, err := FromURL(url, Direct)
+	if err != nil {
+		t.Fatalf("FromURL failed: %v", err)
+	}
+	_, port, err := net.SplitHostPort(endSystem.Addr().String())
+	if err != nil {
+		t.Fatalf("net.SplitHostPort failed: %v", err)
+	}
+	if c, err := proxy.Dial("tcp", "localhost:"+port); err != nil {
+		t.Fatalf("FromURL.Dial failed: %v", err)
+	} else {
+		c.Close()
+	}
+
+	wg.Wait()
+}
+
+func TestSOCKS5(t *testing.T) {
+	endSystem, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("net.Listen failed: %v", err)
+	}
+	defer endSystem.Close()
+	gateway, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		t.Fatalf("net.Listen failed: %v", err)
+	}
+	defer gateway.Close()
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go socks5Gateway(t, gateway, endSystem, socks5IP4, &wg)
+
+	proxy, err := SOCKS5("tcp", gateway.Addr().String(), nil, Direct)
+	if err != nil {
+		t.Fatalf("SOCKS5 failed: %v", err)
+	}
+	if c, err := proxy.Dial("tcp", endSystem.Addr().String()); err != nil {
+		t.Fatalf("SOCKS5.Dial failed: %v", err)
+	} else {
+		c.Close()
+	}
+
+	wg.Wait()
+}
+
+func socks5Gateway(t *testing.T, gateway, endSystem net.Listener, typ byte, wg *sync.WaitGroup) {
+	defer wg.Done()
+
+	c, err := gateway.Accept()
+	if err != nil {
+		t.Errorf("net.Listener.Accept failed: %v", err)
+		return
+	}
+	defer c.Close()
+
+	b := make([]byte, 32)
+	var n int
+	if typ == socks5Domain {
+		n = 4
+	} else {
+		n = 3
+	}
+	if _, err := io.ReadFull(c, b[:n]); err != nil {
+		t.Errorf("io.ReadFull failed: %v", err)
+		return
+	}
+	if _, err := c.Write([]byte{socks5Version, socks5AuthNone}); err != nil {
+		t.Errorf("net.Conn.Write failed: %v", err)
+		return
+	}
+	if typ == socks5Domain {
+		n = 16
+	} else {
+		n = 10
+	}
+	if _, err := io.ReadFull(c, b[:n]); err != nil {
+		t.Errorf("io.ReadFull failed: %v", err)
+		return
+	}
+	if b[0] != socks5Version || b[1] != socks5Connect || b[2] != 0x00 || b[3] != typ {
+		t.Errorf("got an unexpected packet: %#02x %#02x %#02x %#02x", b[0], b[1], b[2], b[3])
+		return
+	}
+	if typ == socks5Domain {
+		copy(b[:5], []byte{socks5Version, 0x00, 0x00, socks5Domain, 9})
+		b = append(b, []byte("localhost")...)
+	} else {
+		copy(b[:4], []byte{socks5Version, 0x00, 0x00, socks5IP4})
+	}
+	host, port, err := net.SplitHostPort(endSystem.Addr().String())
+	if err != nil {
+		t.Errorf("net.SplitHostPort failed: %v", err)
+		return
+	}
+	b = append(b, []byte(net.ParseIP(host).To4())...)
+	p, err := strconv.Atoi(port)
+	if err != nil {
+		t.Errorf("strconv.Atoi failed: %v", err)
+		return
+	}
+	b = append(b, []byte{byte(p >> 8), byte(p)}...)
+	if _, err := c.Write(b); err != nil {
+		t.Errorf("net.Conn.Write failed: %v", err)
+		return
+	}
+}
+
+func ResetProxyEnv() {
+	for _, env := range []*envOnce{allProxyEnv, noProxyEnv} {
+		for _, v := range env.names {
+			os.Setenv(v, "")
+		}
+	}
+	ResetCachedEnvironment()
+}
+
+func ResetCachedEnvironment() {
+	allProxyEnv.reset()
+	noProxyEnv.reset()
+}
@@ -0,0 +1,214 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package proxy
+
+import (
+	"errors"
+	"io"
+	"net"
+	"strconv"
+)
+
+// SOCKS5 returns a Dialer that makes SOCKSv5 connections to the given address
+// with an optional username and password. See RFC 1928 and RFC 1929.
+func SOCKS5(network, addr string, auth *Auth, forward Dialer) (Dialer, error) {
+	s := &socks5{
+		network: network,
+		addr:    addr,
+		forward: forward,
+	}
+	if auth != nil {
+		s.user = auth.User
+		s.password = auth.Password
+	}
+
+	return s, nil
+}
+
+type socks5 struct {
+	user, password string
+	network, addr  string
+	forward        Dialer
+}
+
+const socks5Version = 5
+
+const (
+	socks5AuthNone     = 0
+	socks5AuthPassword = 2
+)
+
+const socks5Connect = 1
+
+const (
+	socks5IP4    = 1
+	socks5Domain = 3
+	socks5IP6    = 4
+)
+
+var socks5Errors = []string{
+	"",
+	"general failure",
+	"connection forbidden",
+	"network unreachable",
+	"host unreachable",
+	"connection refused",
+	"TTL expired",
+	"command not supported",
+	"address type not supported",
+}
+
+// Dial connects to the address addr on the given network via the SOCKS5 proxy.
+func (s *socks5) Dial(network, addr string) (net.Conn, error) {
+	switch network {
+	case "tcp", "tcp6", "tcp4":
+	default:
+		return nil, errors.New("proxy: no support for SOCKS5 proxy connections of type " + network)
+	}
+
+	conn, err := s.forward.Dial(s.network, s.addr)
+	if err != nil {
+		return nil, err
+	}
+	if err := s.connect(conn, addr); err != nil {
+		conn.Close()
+		return nil, err
+	}
+	return conn, nil
+}
+
+// connect takes an existing connection to a socks5 proxy server,
+// and commands the server to extend that connection to target,
+// which must be a canonical address with a host and port.
+func (s *socks5) connect(conn net.Conn, target string) error {
+	host, portStr, err := net.SplitHostPort(target)
+	if err != nil {
+		return err
+	}
+
+	port, err := strconv.Atoi(portStr)
+	if err != nil {
+		return errors.New("proxy: failed to parse port number: " + portStr)
+	}
+	if port < 1 || port > 0xffff {
+		return errors.New("proxy: port number out of range: " + portStr)
+	}
+
+	// the size here is just an estimate
+	buf := make([]byte, 0, 6+len(host))
+
+	buf = append(buf, socks5Version)
+	if len(s.user) > 0 && len(s.user) < 256 && len(s.password) < 256 {
+		buf = append(buf, 2 /* num auth methods */, socks5AuthNone, socks5AuthPassword)
+	} else {
+		buf = append(buf, 1 /* num auth methods */, socks5AuthNone)
+	}
+
+	if _, err := conn.Write(buf); err != nil {
+		return errors.New("proxy: failed to write greeting to SOCKS5 proxy at " + s.addr + ": " + err.Error())
+	}
+
+	if _, err := io.ReadFull(conn, buf[:2]); err != nil {
+		return errors.New("proxy: failed to read greeting from SOCKS5 proxy at " + s.addr + ": " + err.Error())
+	}
+	if buf[0] != 5 {
+		return errors.New("proxy: SOCKS5 proxy at " + s.addr + " has unexpected version " + strconv.Itoa(int(buf[0])))
+	}
+	if buf[1] == 0xff {
+		return errors.New("proxy: SOCKS5 proxy at " + s.addr + " requires authentication")
+	}
+
+	// See RFC 1929
+	if buf[1] == socks5AuthPassword {
+		buf = buf[:0]
+		buf = append(buf, 1 /* password protocol version */)
+		buf = append(buf, uint8(len(s.user)))
+		buf = append(buf, s.user...)
+		buf = append(buf, uint8(len(s.password)))
+		buf = append(buf, s.password...)
+
+		if _, err := conn.Write(buf); err != nil {
+			return errors.New("proxy: failed to write authentication request to SOCKS5 proxy at " + s.addr + ": " + err.Error())
+		}
+
+		if _, err := io.ReadFull(conn, buf[:2]); err != nil {
+			return errors.New("proxy: failed to read authentication reply from SOCKS5 proxy at " + s.addr + ": " + err.Error())
+		}
+
+		if buf[1] != 0 {
+			return errors.New("proxy: SOCKS5 proxy at " + s.addr + " rejected username/password")
+		}
+	}
+
+	buf = buf[:0]
+	buf = append(buf, socks5Version, socks5Connect, 0 /* reserved */)
+
+	if ip := net.ParseIP(host); ip != nil {
+		if ip4 := ip.To4(); ip4 != nil {
+			buf = append(buf, socks5IP4)
+			ip = ip4
+		} else {
+			buf = append(buf, socks5IP6)
+		}
+		buf = append(buf, ip...)
+	} else {
+		if len(host) > 255 {
+			return errors.New("proxy: destination host name too long: " + host)
+		}
+		buf = append(buf, socks5Domain)
+		buf = append(buf, byte(len(host)))
+		buf = append(buf, host...)
+	}
+	buf = append(buf, byte(port>>8), byte(port))
+
+	if _, err := conn.Write(buf); err != nil {
+		return errors.New("proxy: failed to write connect request to SOCKS5 proxy at " + s.addr + ": " + err.Error())
+	}
+
+	if _, err := io.ReadFull(conn, buf[:4]); err != nil {
+		return errors.New("proxy: failed to read connect reply from SOCKS5 proxy at " + s.addr + ": " + err.Error())
+	}
+
+	failure := "unknown error"
+	if int(buf[1]) < len(socks5Errors) {
+		failure = socks5Errors[buf[1]]
+	}
+
+	if len(failure) > 0 {
+		return errors.New("proxy: SOCKS5 proxy at " + s.addr + " failed to connect: " + failure)
+	}
+
+	bytesToDiscard := 0
+	switch buf[3] {
+	case socks5IP4:
+		bytesToDiscard = net.IPv4len
+	case socks5IP6:
+		bytesToDiscard = net.IPv6len
+	case socks5Domain:
+		_, err := io.ReadFull(conn, buf[:1])
+		if err != nil {
+			return errors.New("proxy: failed to read domain length from SOCKS5 proxy at " + s.addr + ": " + err.Error())
+		}
+		bytesToDiscard = int(buf[0])
+	default:
+		return errors.New("proxy: got unknown address type " + strconv.Itoa(int(buf[3])) + " from SOCKS5 proxy at " + s.addr)
+	}
+
+	if cap(buf) < bytesToDiscard {
+		buf = make([]byte, bytesToDiscard)
+	} else {
+		buf = buf[:bytesToDiscard]
+	}
+	if _, err := io.ReadFull(conn, buf); err != nil {
+		return errors.New("proxy: failed to read address from SOCKS5 proxy at " + s.addr + ": " + err.Error())
+	}
+
+	// Also need to discard the port number
+	if _, err := io.ReadFull(conn, buf[:2]); err != nil {
+		return errors.New("proxy: failed to read port from SOCKS5 proxy at " + s.addr + ": " + err.Error())
+	}
+
+	return nil
+}