internal/socks/socks.go - net - Git at Google

 // 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) > 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)))
 }
	// 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) > 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)))
	}