Add SOCKS5 proxy support

commands/dispatch.go

@@ -114,13 +114,20 @@ func init() {
 
 	viper.SetDefault("auto_ctcp", true)
 	viper.SetDefault("verify_certificates", true)
+
 	viper.SetDefault("https.enabled", true)
 	viper.SetDefault("https.port", 443)
+
 	viper.SetDefault("auth.anonymous", true)
 	viper.SetDefault("auth.login", true)
 	viper.SetDefault("auth.registration", true)
+
 	viper.SetDefault("dcc.enabled", true)
 	viper.SetDefault("dcc.autoget.delete", true)
+
+	viper.SetDefault("proxy.protocol", "socks5")
+	viper.SetDefault("proxy.host", "127.0.0.1")
+	viper.SetDefault("proxy.port", 1080)
 }
 
 func initConfig(configPath string, overwrite bool) error {

config.default.toml

@@ -79,6 +79,15 @@ delete = true
 # Delete the file after a certain time period of inactivity, not implemented yet
 delete_after = "30m"
 
+[proxy]
+# Dispatch will make all outgoing connections through the specified proxy when enabled
+enabled = false
+protocol = "socks5"
+host = "127.0.0.1"
+port = 1080
+username = ""
+password = ""
+
 # HTTP Strict-Transport-Security
 [https.hsts]
 enabled = false

config/config.go

@@ -21,6 +21,7 @@ type Config struct {
 	LetsEncrypt        LetsEncrypt
 	Auth               Auth
 	DCC                DCC
+	Proxy              Proxy
 }
 
 type Defaults struct {
@@ -77,6 +78,15 @@ type Autoget struct {
 	DeleteAfter time.Duration `mapstructure:"delete_after"`
 }
 
+type Proxy struct {
+	Enabled  bool
+	Protocol string
+	Host     string
+	Port     string
+	Username string
+	Password string
+}
+
 func LoadConfig() (*Config, chan *Config) {
 	viper.SetConfigName("config")
 	viper.AddConfigPath(storage.Path.ConfigRoot())

pkg/irc/client.go

@@ -33,6 +33,8 @@ type Config struct {
 	Source string
 
 	HandleNickInUse func(string) string
+
+	Dialer Dialer
 }
 
 type Client struct {
@@ -56,7 +58,7 @@ type Client struct {
 	conn       net.Conn
 	connected  bool
 	registered bool
-	dialer     *net.Dialer
+	dialer     Dialer
 	recvBuf    []byte
 	scan       *bufio.Scanner
 	backoff    *backoff.Backoff
@@ -89,6 +91,10 @@ func NewClient(config *Config) *Client {
 		config.SASLMechanisms = DefaultSASLMechanisms
 	}
 
+	if config.Dialer == nil {
+		config.Dialer = DefaultDialer
+	}
+
 	client := &Client{
 		Config:                config,
 		Messages:              make(chan *Message, 32),
@@ -97,7 +103,7 @@ func NewClient(config *Config) *Client {
 		nick:                  config.Nick,
 		requestedCapabilities: map[string][]string{},
 		enabledCapabilities:   map[string][]string{},
-		dialer:                &net.Dialer{Timeout: 10 * time.Second},
+		dialer:                config.Dialer,
 		recvBuf:               make([]byte, 0, 4096),
 		backoff: &backoff.Backoff{
 			Min:    500 * time.Millisecond,

pkg/irc/conn.go

@@ -12,9 +12,15 @@ import (
 )
 
 var (
+	DefaultDialer = &net.Dialer{Timeout: 10 * time.Second}
+
 	ErrBadProtocol = errors.New("This server does not speak IRC")
 )
 
+type Dialer interface {
+	Dial(network, address string) (net.Conn, error)
+}
+
 func (c *Client) Connect() {
 	c.connChange(false, nil)
 	go c.run()
@@ -119,23 +125,23 @@ func (c *Client) connect() error {
 	c.lock.Lock()
 	defer c.lock.Unlock()
 
-	addr := net.JoinHostPort(c.Config.Host, c.Config.Port)
+	conn, err := c.dialer.Dial("tcp", net.JoinHostPort(c.Config.Host, c.Config.Port))
+	if err != nil {
+		return err
+	}
+
 	if c.Config.TLS {
-		conn, err := tls.DialWithDialer(c.dialer, "tcp", addr, c.Config.TLSConfig)
+		c.Config.TLSConfig.ServerName = c.Config.Host
+
+		tlsConn := tls.Client(conn, c.Config.TLSConfig)
+		err = tlsConn.Handshake()
 		if err != nil {
 			return err
 		}
-
+		conn = tlsConn
-		c.conn = conn
-	} else {
-		conn, err := c.dialer.Dial("tcp", addr)
-		if err != nil {
-			return err
 	}
 
 	c.conn = conn
-	}
-
 	c.connected = true
 	c.connChange(true, nil)
 	c.scan = bufio.NewScanner(c.conn)

pkg/irc/dcc.go

@@ -17,9 +17,11 @@ type DCCSend struct {
 	IP     string `json:"ip"`
 	Port   string `json:"port"`
 	Length uint64 `json:"length"`
+
+	dialer Dialer
 }
 
-func ParseDCCSend(ctcp *CTCP) *DCCSend {
+func (c *Client) ParseDCCSend(ctcp *CTCP) *DCCSend {
 	params := strings.Split(ctcp.Params, " ")
 
 	if len(params) > 4 {
@@ -43,20 +45,21 @@ func ParseDCCSend(ctcp *CTCP) *DCCSend {
 			IP:     intToIP(ip),
 			Port:   params[3],
 			Length: length,
+			dialer: c.dialer,
 		}
 	}
 
 	return nil
 }
 
-func DownloadDCC(w io.Writer, pack *DCCSend, progress chan DownloadProgress) error {
+func (pack *DCCSend) Download(w io.Writer, progress chan DownloadProgress) error {
 	if progress != nil {
 		progress <- DownloadProgress{
 			File: pack.File,
 		}
 	}
 
-	conn, err := net.DialTimeout("tcp", net.JoinHostPort(pack.IP, pack.Port), 10*time.Second)
+	conn, err := pack.dialer.Dial("tcp", net.JoinHostPort(pack.IP, pack.Port))
 	if err != nil {
 		return err
 	}

server/irc.go

@@ -4,9 +4,13 @@ import (
 	"crypto/tls"
 	"encoding/hex"
 	"fmt"
+	"log"
+	"net"
+	"strings"
 
 	"github.com/khlieng/dispatch/pkg/irc"
 	"github.com/khlieng/dispatch/storage"
+	"golang.org/x/net/proxy"
 )
 
 func createNickInUseHandler(i *irc.Client, state *State) func(string) string {
@@ -54,6 +58,25 @@ func connectIRC(network *storage.Network, state *State, srcIP []byte) *irc.Clien
 		ircCfg.ServerPassword = cfg.Defaults.ServerPassword
 	}
 
+	if cfg.Proxy.Enabled && strings.ToLower(cfg.Proxy.Protocol) == "socks5" {
+		addr := net.JoinHostPort(cfg.Proxy.Host, cfg.Proxy.Port)
+
+		var auth *proxy.Auth
+		if cfg.Proxy.Username != "" {
+			auth = &proxy.Auth{
+				User:     cfg.Proxy.Username,
+				Password: cfg.Proxy.Password,
+			}
+		}
+
+		dialer, err := proxy.SOCKS5("tcp", addr, auth, irc.DefaultDialer)
+		if err != nil {
+			log.Println(err)
+		} else {
+			ircCfg.Dialer = dialer
+		}
+	}
+
 	i := irc.NewClient(ircCfg)
 	i.Config.HandleNickInUse = createNickInUseHandler(i, state)
 

server/irc_handler.go

@@ -231,7 +231,7 @@ func (i *ircHandler) mode(msg *irc.Message) {
 func (i *ircHandler) message(msg *irc.Message) {
 	if ctcp := msg.ToCTCP(); ctcp != nil {
 		if ctcp.Command == "DCC" && strings.HasPrefix(ctcp.Params, "SEND") {
-			if pack := irc.ParseDCCSend(ctcp); pack != nil {
+			if pack := i.client.ParseDCCSend(ctcp); pack != nil {
 				go i.receiveDCCSend(pack, msg)
 				return
 			}
@@ -470,7 +470,7 @@ func (i *ircHandler) receiveDCCSend(pack *irc.DCCSend, msg *irc.Message) {
 			}
 			defer file.Close()
 
-			irc.DownloadDCC(file, pack, i.dccProgress)
+			pack.Download(file, i.dccProgress)
 		} else {
 			i.state.setPendingDCC(pack.File, pack)
 

server/server.go

@@ -11,7 +11,6 @@ import (
 	"github.com/gorilla/websocket"
 	"github.com/khlieng/dispatch/config"
 	"github.com/khlieng/dispatch/pkg/https"
-	"github.com/khlieng/dispatch/pkg/irc"
 	"github.com/khlieng/dispatch/pkg/session"
 	"github.com/khlieng/dispatch/storage"
 )
@@ -195,7 +194,7 @@ func (d *Dispatch) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 				state.deletePendingDCC(filename)
 
 				w.Header().Set("Content-Length", strconv.FormatUint(pack.Length, 10))
-				irc.DownloadDCC(w, pack, nil)
+				pack.Download(w, nil)
 			} else {
 				file := storage.Path.DownloadedFile(state.user.Username, filename)
 				http.ServeFile(w, r, file)

vendor/golang.org/x/net/internal/socks/client.go

@@ -0,0 +1,168 @@
+// Copyright 2018 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 socks
+
+import (
+	"context"
+	"errors"
+	"io"
+	"net"
+	"strconv"
+	"time"
+)
+
+var (
+	noDeadline   = time.Time{}
+	aLongTimeAgo = time.Unix(1, 0)
+)
+
+func (d *Dialer) connect(ctx context.Context, c net.Conn, address string) (_ net.Addr, ctxErr error) {
+	host, port, err := splitHostPort(address)
+	if err != nil {
+		return nil, err
+	}
+	if deadline, ok := ctx.Deadline(); ok && !deadline.IsZero() {
+		c.SetDeadline(deadline)
+		defer c.SetDeadline(noDeadline)
+	}
+	if ctx != context.Background() {
+		errCh := make(chan error, 1)
+		done := make(chan struct{})
+		defer func() {
+			close(done)
+			if ctxErr == nil {
+				ctxErr = <-errCh
+			}
+		}()
+		go func() {
+			select {
+			case <-ctx.Done():
+				c.SetDeadline(aLongTimeAgo)
+				errCh <- ctx.Err()
+			case <-done:
+				errCh <- nil
+			}
+		}()
+	}
+
+	b := make([]byte, 0, 6+len(host)) // the size here is just an estimate
+	b = append(b, Version5)
+	if len(d.AuthMethods) == 0 || d.Authenticate == nil {
+		b = append(b, 1, byte(AuthMethodNotRequired))
+	} else {
+		ams := d.AuthMethods
+		if len(ams) > 255 {
+			return nil, errors.New("too many authentication methods")
+		}
+		b = append(b, byte(len(ams)))
+		for _, am := range ams {
+			b = append(b, byte(am))
+		}
+	}
+	if _, ctxErr = c.Write(b); ctxErr != nil {
+		return
+	}
+
+	if _, ctxErr = io.ReadFull(c, b[:2]); ctxErr != nil {
+		return
+	}
+	if b[0] != Version5 {
+		return nil, errors.New("unexpected protocol version " + strconv.Itoa(int(b[0])))
+	}
+	am := AuthMethod(b[1])
+	if am == AuthMethodNoAcceptableMethods {
+		return nil, errors.New("no acceptable authentication methods")
+	}
+	if d.Authenticate != nil {
+		if ctxErr = d.Authenticate(ctx, c, am); ctxErr != nil {
+			return
+		}
+	}
+
+	b = b[:0]
+	b = append(b, Version5, byte(d.cmd), 0)
+	if ip := net.ParseIP(host); ip != nil {
+		if ip4 := ip.To4(); ip4 != nil {
+			b = append(b, AddrTypeIPv4)
+			b = append(b, ip4...)
+		} else if ip6 := ip.To16(); ip6 != nil {
+			b = append(b, AddrTypeIPv6)
+			b = append(b, ip6...)
+		} else {
+			return nil, errors.New("unknown address type")
+		}
+	} else {
+		if len(host) > 255 {
+			return nil, errors.New("FQDN too long")
+		}
+		b = append(b, AddrTypeFQDN)
+		b = append(b, byte(len(host)))
+		b = append(b, host...)
+	}
+	b = append(b, byte(port>>8), byte(port))
+	if _, ctxErr = c.Write(b); ctxErr != nil {
+		return
+	}
+
+	if _, ctxErr = io.ReadFull(c, b[:4]); ctxErr != nil {
+		return
+	}
+	if b[0] != Version5 {
+		return nil, errors.New("unexpected protocol version " + strconv.Itoa(int(b[0])))
+	}
+	if cmdErr := Reply(b[1]); cmdErr != StatusSucceeded {
+		return nil, errors.New("unknown error " + cmdErr.String())
+	}
+	if b[2] != 0 {
+		return nil, errors.New("non-zero reserved field")
+	}
+	l := 2
+	var a Addr
+	switch b[3] {
+	case AddrTypeIPv4:
+		l += net.IPv4len
+		a.IP = make(net.IP, net.IPv4len)
+	case AddrTypeIPv6:
+		l += net.IPv6len
+		a.IP = make(net.IP, net.IPv6len)
+	case AddrTypeFQDN:
+		if _, err := io.ReadFull(c, b[:1]); err != nil {
+			return nil, err
+		}
+		l += int(b[0])
+	default:
+		return nil, errors.New("unknown address type " + strconv.Itoa(int(b[3])))
+	}
+	if cap(b) < l {
+		b = make([]byte, l)
+	} else {
+		b = b[:l]
+	}
+	if _, ctxErr = io.ReadFull(c, b); ctxErr != nil {
+		return
+	}
+	if a.IP != nil {
+		copy(a.IP, b)
+	} else {
+		a.Name = string(b[:len(b)-2])
+	}
+	a.Port = int(b[len(b)-2])<<8 | int(b[len(b)-1])
+	return &a, nil
+}
+
+func splitHostPort(address string) (string, int, error) {
+	host, port, err := net.SplitHostPort(address)
+	if err != nil {
+		return "", 0, err
+	}
+	portnum, err := strconv.Atoi(port)
+	if err != nil {
+		return "", 0, err
+	}
+	if 1 > portnum || portnum > 0xffff {
+		return "", 0, errors.New("port number out of range " + port)
+	}
+	return host, portnum, nil
+}

vendor/golang.org/x/net/internal/socks/socks.go

@@ -0,0 +1,317 @@
+// Copyright 2018 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 socks provides a SOCKS version 5 client implementation.
+//
+// SOCKS protocol version 5 is defined in RFC 1928.
+// Username/Password authentication for SOCKS version 5 is defined in
+// RFC 1929.
+package socks
+
+import (
+	"context"
+	"errors"
+	"io"
+	"net"
+	"strconv"
+)
+
+// A Command represents a SOCKS command.
+type Command int
+
+func (cmd Command) String() string {
+	switch cmd {
+	case CmdConnect:
+		return "socks connect"
+	case cmdBind:
+		return "socks bind"
+	default:
+		return "socks " + strconv.Itoa(int(cmd))
+	}
+}
+
+// An AuthMethod represents a SOCKS authentication method.
+type AuthMethod int
+
+// A Reply represents a SOCKS command reply code.
+type Reply int
+
+func (code Reply) String() string {
+	switch code {
+	case StatusSucceeded:
+		return "succeeded"
+	case 0x01:
+		return "general SOCKS server failure"
+	case 0x02:
+		return "connection not allowed by ruleset"
+	case 0x03:
+		return "network unreachable"
+	case 0x04:
+		return "host unreachable"
+	case 0x05:
+		return "connection refused"
+	case 0x06:
+		return "TTL expired"
+	case 0x07:
+		return "command not supported"
+	case 0x08:
+		return "address type not supported"
+	default:
+		return "unknown code: " + strconv.Itoa(int(code))
+	}
+}
+
+// Wire protocol constants.
+const (
+	Version5 = 0x05
+
+	AddrTypeIPv4 = 0x01
+	AddrTypeFQDN = 0x03
+	AddrTypeIPv6 = 0x04
+
+	CmdConnect Command = 0x01 // establishes an active-open forward proxy connection
+	cmdBind    Command = 0x02 // establishes a passive-open forward proxy connection
+
+	AuthMethodNotRequired         AuthMethod = 0x00 // no authentication required
+	AuthMethodUsernamePassword    AuthMethod = 0x02 // use username/password
+	AuthMethodNoAcceptableMethods AuthMethod = 0xff // no acceptable authentication methods
+
+	StatusSucceeded Reply = 0x00
+)
+
+// An Addr represents a SOCKS-specific address.
+// Either Name or IP is used exclusively.
+type Addr struct {
+	Name string // fully-qualified domain name
+	IP   net.IP
+	Port int
+}
+
+func (a *Addr) Network() string { return "socks" }
+
+func (a *Addr) String() string {
+	if a == nil {
+		return "<nil>"
+	}
+	port := strconv.Itoa(a.Port)
+	if a.IP == nil {
+		return net.JoinHostPort(a.Name, port)
+	}
+	return net.JoinHostPort(a.IP.String(), port)
+}
+
+// A Conn represents a forward proxy connection.
+type Conn struct {
+	net.Conn
+
+	boundAddr net.Addr
+}
+
+// BoundAddr returns the address assigned by the proxy server for
+// connecting to the command target address from the proxy server.
+func (c *Conn) BoundAddr() net.Addr {
+	if c == nil {
+		return nil
+	}
+	return c.boundAddr
+}
+
+// A Dialer holds SOCKS-specific options.
+type Dialer struct {
+	cmd          Command // either CmdConnect or cmdBind
+	proxyNetwork string  // network between a proxy server and a client
+	proxyAddress string  // proxy server address
+
+	// ProxyDial specifies the optional dial function for
+	// establishing the transport connection.
+	ProxyDial func(context.Context, string, string) (net.Conn, error)
+
+	// AuthMethods specifies the list of request authentication
+	// methods.
+	// If empty, SOCKS client requests only AuthMethodNotRequired.
+	AuthMethods []AuthMethod
+
+	// Authenticate specifies the optional authentication
+	// function. It must be non-nil when AuthMethods is not empty.
+	// It must return an error when the authentication is failed.
+	Authenticate func(context.Context, io.ReadWriter, AuthMethod) error
+}
+
+// DialContext connects to the provided address on the provided
+// network.
+//
+// The returned error value may be a net.OpError. When the Op field of
+// net.OpError contains "socks", the Source field contains a proxy
+// server address and the Addr field contains a command target
+// address.
+//
+// See func Dial of the net package of standard library for a
+// description of the network and address parameters.
+func (d *Dialer) DialContext(ctx context.Context, network, address string) (net.Conn, error) {
+	if err := d.validateTarget(network, address); err != nil {
+		proxy, dst, _ := d.pathAddrs(address)
+		return nil, &net.OpError{Op: d.cmd.String(), Net: network, Source: proxy, Addr: dst, Err: err}
+	}
+	if ctx == nil {
+		proxy, dst, _ := d.pathAddrs(address)
+		return nil, &net.OpError{Op: d.cmd.String(), Net: network, Source: proxy, Addr: dst, Err: errors.New("nil context")}
+	}
+	var err error
+	var c net.Conn
+	if d.ProxyDial != nil {
+		c, err = d.ProxyDial(ctx, d.proxyNetwork, d.proxyAddress)
+	} else {
+		var dd net.Dialer
+		c, err = dd.DialContext(ctx, d.proxyNetwork, d.proxyAddress)
+	}
+	if err != nil {
+		proxy, dst, _ := d.pathAddrs(address)
+		return nil, &net.OpError{Op: d.cmd.String(), Net: network, Source: proxy, Addr: dst, Err: err}
+	}
+	a, err := d.connect(ctx, c, address)
+	if err != nil {
+		c.Close()
+		proxy, dst, _ := d.pathAddrs(address)
+		return nil, &net.OpError{Op: d.cmd.String(), Net: network, Source: proxy, Addr: dst, Err: err}
+	}
+	return &Conn{Conn: c, boundAddr: a}, nil
+}
+
+// DialWithConn initiates a connection from SOCKS server to the target
+// network and address using the connection c that is already
+// connected to the SOCKS server.
+//
+// It returns the connection's local address assigned by the SOCKS
+// server.
+func (d *Dialer) DialWithConn(ctx context.Context, c net.Conn, network, address string) (net.Addr, error) {
+	if err := d.validateTarget(network, address); err != nil {
+		proxy, dst, _ := d.pathAddrs(address)
+		return nil, &net.OpError{Op: d.cmd.String(), Net: network, Source: proxy, Addr: dst, Err: err}
+	}
+	if ctx == nil {
+		proxy, dst, _ := d.pathAddrs(address)
+		return nil, &net.OpError{Op: d.cmd.String(), Net: network, Source: proxy, Addr: dst, Err: errors.New("nil context")}
+	}
+	a, err := d.connect(ctx, c, address)
+	if err != nil {
+		proxy, dst, _ := d.pathAddrs(address)
+		return nil, &net.OpError{Op: d.cmd.String(), Net: network, Source: proxy, Addr: dst, Err: err}
+	}
+	return a, nil
+}
+
+// Dial connects to the provided address on the provided network.
+//
+// Unlike DialContext, it returns a raw transport connection instead
+// of a forward proxy connection.
+//
+// Deprecated: Use DialContext or DialWithConn instead.
+func (d *Dialer) Dial(network, address string) (net.Conn, error) {
+	if err := d.validateTarget(network, address); err != nil {
+		proxy, dst, _ := d.pathAddrs(address)
+		return nil, &net.OpError{Op: d.cmd.String(), Net: network, Source: proxy, Addr: dst, Err: err}
+	}
+	var err error
+	var c net.Conn
+	if d.ProxyDial != nil {
+		c, err = d.ProxyDial(context.Background(), d.proxyNetwork, d.proxyAddress)
+	} else {
+		c, err = net.Dial(d.proxyNetwork, d.proxyAddress)
+	}
+	if err != nil {
+		proxy, dst, _ := d.pathAddrs(address)
+		return nil, &net.OpError{Op: d.cmd.String(), Net: network, Source: proxy, Addr: dst, Err: err}
+	}
+	if _, err := d.DialWithConn(context.Background(), c, network, address); err != nil {
+		c.Close()
+		return nil, err
+	}
+	return c, nil
+}
+
+func (d *Dialer) validateTarget(network, address string) error {
+	switch network {
+	case "tcp", "tcp6", "tcp4":
+	default:
+		return errors.New("network not implemented")
+	}
+	switch d.cmd {
+	case CmdConnect, cmdBind:
+	default:
+		return errors.New("command not implemented")
+	}
+	return nil
+}
+
+func (d *Dialer) pathAddrs(address string) (proxy, dst net.Addr, err error) {
+	for i, s := range []string{d.proxyAddress, address} {
+		host, port, err := splitHostPort(s)
+		if err != nil {
+			return nil, nil, err
+		}
+		a := &Addr{Port: port}
+		a.IP = net.ParseIP(host)
+		if a.IP == nil {
+			a.Name = host
+		}
+		if i == 0 {
+			proxy = a
+		} else {
+			dst = a
+		}
+	}
+	return
+}
+
+// NewDialer returns a new Dialer that dials through the provided
+// proxy server's network and address.
+func NewDialer(network, address string) *Dialer {
+	return &Dialer{proxyNetwork: network, proxyAddress: address, cmd: CmdConnect}
+}
+
+const (
+	authUsernamePasswordVersion = 0x01
+	authStatusSucceeded         = 0x00
+)
+
+// UsernamePassword are the credentials for the username/password
+// authentication method.
+type UsernamePassword struct {
+	Username string
+	Password string
+}
+
+// Authenticate authenticates a pair of username and password with the
+// proxy server.
+func (up *UsernamePassword) Authenticate(ctx context.Context, rw io.ReadWriter, auth AuthMethod) error {
+	switch auth {
+	case AuthMethodNotRequired:
+		return nil
+	case AuthMethodUsernamePassword:
+		if len(up.Username) == 0 || len(up.Username) > 255 || len(up.Password) == 0 || len(up.Password) > 255 {
+			return errors.New("invalid username/password")
+		}
+		b := []byte{authUsernamePasswordVersion}
+		b = append(b, byte(len(up.Username)))
+		b = append(b, up.Username...)
+		b = append(b, byte(len(up.Password)))
+		b = append(b, up.Password...)
+		// TODO(mikio): handle IO deadlines and cancelation if
+		// necessary
+		if _, err := rw.Write(b); err != nil {
+			return err
+		}
+		if _, err := io.ReadFull(rw, b[:2]); err != nil {
+			return err
+		}
+		if b[0] != authUsernamePasswordVersion {
+			return errors.New("invalid username/password version")
+		}
+		if b[1] != authStatusSucceeded {
+			return errors.New("username/password authentication failed")
+		}
+		return nil
+	}
+	return errors.New("unsupported authentication method " + strconv.Itoa(int(auth)))
+}

vendor/golang.org/x/net/proxy/dial.go

@@ -0,0 +1,54 @@
+// Copyright 2019 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 (
+	"context"
+	"net"
+)
+
+// A ContextDialer dials using a context.
+type ContextDialer interface {
+	DialContext(ctx context.Context, network, address string) (net.Conn, error)
+}
+
+// Dial works like DialContext on net.Dialer but using a dialer returned by FromEnvironment.
+//
+// The passed ctx is only used for returning the Conn, not the lifetime of the Conn.
+//
+// Custom dialers (registered via RegisterDialerType) that do not implement ContextDialer
+// can leak a goroutine for as long as it takes the underlying Dialer implementation to timeout.
+//
+// A Conn returned from a successful Dial after the context has been cancelled will be immediately closed.
+func Dial(ctx context.Context, network, address string) (net.Conn, error) {
+	d := FromEnvironment()
+	if xd, ok := d.(ContextDialer); ok {
+		return xd.DialContext(ctx, network, address)
+	}
+	return dialContext(ctx, d, network, address)
+}
+
+// WARNING: this can leak a goroutine for as long as the underlying Dialer implementation takes to timeout
+// A Conn returned from a successful Dial after the context has been cancelled will be immediately closed.
+func dialContext(ctx context.Context, d Dialer, network, address string) (net.Conn, error) {
+	var (
+		conn net.Conn
+		done = make(chan struct{}, 1)
+		err  error
+	)
+	go func() {
+		conn, err = d.Dial(network, address)
+		close(done)
+		if conn != nil && ctx.Err() != nil {
+			conn.Close()
+		}
+	}()
+	select {
+	case <-ctx.Done():
+		err = ctx.Err()
+	case <-done:
+	}
+	return conn, err
+}

vendor/golang.org/x/net/proxy/direct.go

@@ -0,0 +1,31 @@
+// 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 (
+	"context"
+	"net"
+)
+
+type direct struct{}
+
+// Direct implements Dialer by making network connections directly using net.Dial or net.DialContext.
+var Direct = direct{}
+
+var (
+	_ Dialer        = Direct
+	_ ContextDialer = Direct
+)
+
+// Dial directly invokes net.Dial with the supplied parameters.
+func (direct) Dial(network, addr string) (net.Conn, error) {
+	return net.Dial(network, addr)
+}
+
+// DialContext instantiates a net.Dialer and invokes its DialContext receiver with the supplied parameters.
+func (direct) DialContext(ctx context.Context, network, addr string) (net.Conn, error) {
+	var d net.Dialer
+	return d.DialContext(ctx, network, addr)
+}

vendor/golang.org/x/net/proxy/per_host.go

@@ -0,0 +1,155 @@
+// 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 (
+	"context"
+	"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)
+}
+
+// DialContext connects to the address addr on the given network through either
+// defaultDialer or bypass.
+func (p *PerHost) DialContext(ctx context.Context, network, addr string) (c net.Conn, err error) {
+	host, _, err := net.SplitHostPort(addr)
+	if err != nil {
+		return nil, err
+	}
+	d := p.dialerForRequest(host)
+	if x, ok := d.(ContextDialer); ok {
+		return x.DialContext(ctx, network, addr)
+	}
+	return dialContext(ctx, d, 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)
+}

vendor/golang.org/x/net/proxy/proxy.go

@@ -0,0 +1,149 @@
+// 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.
+// Custom dialers should also implement ContextDialer.
+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 and makes underlying connections
+// directly.
+func FromEnvironment() Dialer {
+	return FromEnvironmentUsing(Direct)
+}
+
+// FromEnvironmentUsing returns the dialer specify by the proxy-related
+// variables in the environment and makes underlying connections
+// using the provided forwarding Dialer (for instance, a *net.Dialer
+// with desired configuration).
+func FromEnvironmentUsing(forward Dialer) Dialer {
+	allProxy := allProxyEnv.Get()
+	if len(allProxy) == 0 {
+		return forward
+	}
+
+	proxyURL, err := url.Parse(allProxy)
+	if err != nil {
+		return forward
+	}
+	proxy, err := FromURL(proxyURL, forward)
+	if err != nil {
+		return forward
+	}
+
+	noProxy := noProxyEnv.Get()
+	if len(noProxy) == 0 {
+		return proxy
+	}
+
+	perHost := NewPerHost(proxy, forward)
+	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", "socks5h":
+		addr := u.Hostname()
+		port := u.Port()
+		if port == "" {
+			port = "1080"
+		}
+		return SOCKS5("tcp", net.JoinHostPort(addr, port), 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 = ""
+}

vendor/golang.org/x/net/proxy/socks5.go

@@ -0,0 +1,42 @@
+// 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 (
+	"context"
+	"net"
+
+	"golang.org/x/net/internal/socks"
+)
+
+// 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, address string, auth *Auth, forward Dialer) (Dialer, error) {
+	d := socks.NewDialer(network, address)
+	if forward != nil {
+		if f, ok := forward.(ContextDialer); ok {
+			d.ProxyDial = func(ctx context.Context, network string, address string) (net.Conn, error) {
+				return f.DialContext(ctx, network, address)
+			}
+		} else {
+			d.ProxyDial = func(ctx context.Context, network string, address string) (net.Conn, error) {
+				return dialContext(ctx, forward, network, address)
+			}
+		}
+	}
+	if auth != nil {
+		up := socks.UsernamePassword{
+			Username: auth.User,
+			Password: auth.Password,
+		}
+		d.AuthMethods = []socks.AuthMethod{
+			socks.AuthMethodNotRequired,
+			socks.AuthMethodUsernamePassword,
+		}
+		d.Authenticate = up.Authenticate
+	}
+	return d, nil
+}

vendor/modules.txt

@@ -243,8 +243,10 @@ golang.org/x/net/html/atom
 golang.org/x/net/idna
 golang.org/x/net/internal/iana
 golang.org/x/net/internal/socket
+golang.org/x/net/internal/socks
 golang.org/x/net/ipv4
 golang.org/x/net/ipv6
+golang.org/x/net/proxy
 # golang.org/x/sys v0.0.0-20200610111108-226ff32320da
 ## explicit
 golang.org/x/sys/internal/unsafeheader