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// 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 sockstest provides utilities for SOCKS testing.
package sockstest
import (
"errors"
"io"
"net"
"golang.org/x/net/internal/nettest"
"golang.org/x/net/internal/socks"
)
// An AuthRequest represents an authentication request.
type AuthRequest struct {
Version int
Methods []socks.AuthMethod
}
// ParseAuthRequest parses an authentication request.
func ParseAuthRequest(b []byte) (*AuthRequest, error) {
if len(b) < 2 {
return nil, errors.New("short auth request")
}
if b[0] != socks.Version5 {
return nil, errors.New("unexpected protocol version")
}
if len(b)-2 < int(b[1]) {
return nil, errors.New("short auth request")
}
req := &AuthRequest{Version: int(b[0])}
if b[1] > 0 {
req.Methods = make([]socks.AuthMethod, b[1])
for i, m := range b[2 : 2+b[1]] {
req.Methods[i] = socks.AuthMethod(m)
}
}
return req, nil
}
// MarshalAuthReply returns an authentication reply in wire format.
func MarshalAuthReply(ver int, m socks.AuthMethod) ([]byte, error) {
return []byte{byte(ver), byte(m)}, nil
}
// A CmdRequest repesents a command request.
type CmdRequest struct {
Version int
Cmd socks.Command
Addr socks.Addr
}
// ParseCmdRequest parses a command request.
func ParseCmdRequest(b []byte) (*CmdRequest, error) {
if len(b) < 7 {
return nil, errors.New("short cmd request")
}
if b[0] != socks.Version5 {
return nil, errors.New("unexpected protocol version")
}
if socks.Command(b[1]) != socks.CmdConnect {
return nil, errors.New("unexpected command")
}
if b[2] != 0 {
return nil, errors.New("non-zero reserved field")
}
req := &CmdRequest{Version: int(b[0]), Cmd: socks.Command(b[1])}
l := 2
off := 4
switch b[3] {
case socks.AddrTypeIPv4:
l += net.IPv4len
req.Addr.IP = make(net.IP, net.IPv4len)
case socks.AddrTypeIPv6:
l += net.IPv6len
req.Addr.IP = make(net.IP, net.IPv6len)
case socks.AddrTypeFQDN:
l += int(b[4])
off = 5
default:
return nil, errors.New("unknown address type")
}
if len(b[off:]) < l {
return nil, errors.New("short cmd request")
}
if req.Addr.IP != nil {
copy(req.Addr.IP, b[off:])
} else {
req.Addr.Name = string(b[off : off+l-2])
}
req.Addr.Port = int(b[off+l-2])<<8 | int(b[off+l-1])
return req, nil
}
// MarshalCmdReply returns a command reply in wire format.
func MarshalCmdReply(ver int, reply socks.Reply, a *socks.Addr) ([]byte, error) {
b := make([]byte, 4)
b[0] = byte(ver)
b[1] = byte(reply)
if a.Name != "" {
if len(a.Name) > 255 {
return nil, errors.New("fqdn too long")
}
b[3] = socks.AddrTypeFQDN
b = append(b, byte(len(a.Name)))
b = append(b, a.Name...)
} else if ip4 := a.IP.To4(); ip4 != nil {
b[3] = socks.AddrTypeIPv4
b = append(b, ip4...)
} else if ip6 := a.IP.To16(); ip6 != nil {
b[3] = socks.AddrTypeIPv6
b = append(b, ip6...)
} else {
return nil, errors.New("unknown address type")
}
b = append(b, byte(a.Port>>8), byte(a.Port))
return b, nil
}
// A Server repesents a server for handshake testing.
type Server struct {
ln net.Listener
}
// Addr rerurns a server address.
func (s *Server) Addr() net.Addr {
return s.ln.Addr()
}
// TargetAddr returns a fake final destination address.
//
// The returned address is only valid for testing with Server.
func (s *Server) TargetAddr() net.Addr {
a := s.ln.Addr()
switch a := a.(type) {
case *net.TCPAddr:
if a.IP.To4() != nil {
return &net.TCPAddr{IP: net.IPv4(127, 0, 0, 1), Port: 5963}
}
if a.IP.To16() != nil && a.IP.To4() == nil {
return &net.TCPAddr{IP: net.IPv6loopback, Port: 5963}
}
}
return nil
}
// Close closes the server.
func (s *Server) Close() error {
return s.ln.Close()
}
func (s *Server) serve(authFunc, cmdFunc func(io.ReadWriter, []byte) error) {
c, err := s.ln.Accept()
if err != nil {
return
}
defer c.Close()
go s.serve(authFunc, cmdFunc)
b := make([]byte, 512)
n, err := c.Read(b)
if err != nil {
return
}
if err := authFunc(c, b[:n]); err != nil {
return
}
n, err = c.Read(b)
if err != nil {
return
}
if err := cmdFunc(c, b[:n]); err != nil {
return
}
}
// NewServer returns a new server.
//
// The provided authFunc and cmdFunc must parse requests and return
// appropriate replies to clients.
func NewServer(authFunc, cmdFunc func(io.ReadWriter, []byte) error) (*Server, error) {
var err error
s := new(Server)
s.ln, err = nettest.NewLocalListener("tcp")
if err != nil {
return nil, err
}
go s.serve(authFunc, cmdFunc)
return s, nil
}
// NoAuthRequired handles a no-authentication-required signaling.
func NoAuthRequired(rw io.ReadWriter, b []byte) error {
req, err := ParseAuthRequest(b)
if err != nil {
return err
}
b, err = MarshalAuthReply(req.Version, socks.AuthMethodNotRequired)
if err != nil {
return err
}
n, err := rw.Write(b)
if err != nil {
return err
}
if n != len(b) {
return errors.New("short write")
}
return nil
}
// NoProxyRequired handles a command signaling without constructing a
// proxy connection to the final destination.
func NoProxyRequired(rw io.ReadWriter, b []byte) error {
req, err := ParseCmdRequest(b)
if err != nil {
return err
}
req.Addr.Port += 1
if req.Addr.Name != "" {
req.Addr.Name = "boundaddr.doesnotexist"
} else if req.Addr.IP.To4() != nil {
req.Addr.IP = net.IPv4(127, 0, 0, 1)
} else {
req.Addr.IP = net.IPv6loopback
}
b, err = MarshalCmdReply(socks.Version5, socks.StatusSucceeded, &req.Addr)
if err != nil {
return err
}
n, err := rw.Write(b)
if err != nil {
return err
}
if n != len(b) {
return errors.New("short write")
}
return nil
}