OpenGFW/analyzer/tcp/socks.go

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package tcp
import (
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"net"
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"github.com/apernet/OpenGFW/analyzer"
"github.com/apernet/OpenGFW/analyzer/utils"
)
const (
SocksInvalid = iota
Socks4
Socks4A
Socks5
Socks4Version = 0x04
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Socks5Version = 0x05
Socks4ReplyVN = 0x00
Socks4CmdTCPConnect = 0x01
Socks4CmdTCPBind = 0x02
Socks4ReqGranted = 0x5A
Socks4ReqRejectOrFailed = 0x5B
Socks4ReqRejectIdentd = 0x5C
Socks4ReqRejectUser = 0x5D
Socks5CmdTCPConnect = 0x01
Socks5CmdTCPBind = 0x02
Socks5CmdUDPAssociate = 0x03
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Socks5AuthNotRequired = 0x00
Socks5AuthPassword = 0x02
Socks5AuthNoMatchingMethod = 0xFF
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Socks5AuthSuccess = 0x00
Socks5AuthFailure = 0x01
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Socks5AddrTypeIPv4 = 0x01
Socks5AddrTypeDomain = 0x03
Socks5AddrTypeIPv6 = 0x04
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)
var _ analyzer.Analyzer = (*SocksAnalyzer)(nil)
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type SocksAnalyzer struct{}
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func (a *SocksAnalyzer) Name() string {
return "socks"
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}
func (a *SocksAnalyzer) Limit() int {
// Socks4 length limit cannot be predicted
return 0
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}
func (a *SocksAnalyzer) NewTCP(info analyzer.TCPInfo, logger analyzer.Logger) analyzer.TCPStream {
return newSocksStream(logger)
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}
type socksStream struct {
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logger analyzer.Logger
reqBuf *utils.ByteBuffer
reqMap analyzer.PropMap
reqUpdated bool
reqLSM *utils.LinearStateMachine
reqDone bool
respBuf *utils.ByteBuffer
respMap analyzer.PropMap
respUpdated bool
respLSM *utils.LinearStateMachine
respDone bool
version int
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authReqMethod int
authUsername string
authPassword string
authRespMethod int
}
func newSocksStream(logger analyzer.Logger) *socksStream {
s := &socksStream{logger: logger, reqBuf: &utils.ByteBuffer{}, respBuf: &utils.ByteBuffer{}}
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s.reqLSM = utils.NewLinearStateMachine(
s.parseSocksReqVersion,
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)
s.respLSM = utils.NewLinearStateMachine(
s.parseSocksRespVersion,
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)
return s
}
func (s *socksStream) Feed(rev, start, end bool, skip int, data []byte) (u *analyzer.PropUpdate, d bool) {
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if skip != 0 {
return nil, true
}
if len(data) == 0 {
return nil, false
}
var update *analyzer.PropUpdate
var cancelled bool
if rev {
s.respBuf.Append(data)
s.respUpdated = false
cancelled, s.respDone = s.respLSM.Run()
if s.respUpdated {
update = &analyzer.PropUpdate{
Type: analyzer.PropUpdateMerge,
M: analyzer.PropMap{"resp": s.respMap},
}
s.respUpdated = false
}
} else {
s.reqBuf.Append(data)
s.reqUpdated = false
cancelled, s.reqDone = s.reqLSM.Run()
if s.reqUpdated {
update = &analyzer.PropUpdate{
Type: analyzer.PropUpdateMerge,
M: analyzer.PropMap{
"version": s.socksVersion(),
"req": s.reqMap,
},
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}
s.reqUpdated = false
}
}
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return update, cancelled || (s.reqDone && s.respDone)
}
func (s *socksStream) Close(limited bool) *analyzer.PropUpdate {
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s.reqBuf.Reset()
s.respBuf.Reset()
s.reqMap = nil
s.respMap = nil
return nil
}
func (s *socksStream) parseSocksReqVersion() utils.LSMAction {
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socksVer, ok := s.reqBuf.GetByte(true)
if !ok {
return utils.LSMActionPause
}
if socksVer != Socks4Version && socksVer != Socks5Version {
return utils.LSMActionCancel
}
s.reqMap = make(analyzer.PropMap)
s.reqUpdated = true
if socksVer == Socks4Version {
s.version = Socks4
s.reqLSM.AppendSteps(
s.parseSocks4ReqIpAndPort,
s.parseSocks4ReqUserId,
s.parseSocks4ReqHostname,
)
} else {
s.version = Socks5
s.reqLSM.AppendSteps(
s.parseSocks5ReqMethod,
s.parseSocks5ReqAuth,
s.parseSocks5ReqConnInfo,
)
}
return utils.LSMActionNext
}
func (s *socksStream) parseSocksRespVersion() utils.LSMAction {
socksVer, ok := s.respBuf.GetByte(true)
if !ok {
return utils.LSMActionPause
}
if (s.version == Socks4 || s.version == Socks4A) && socksVer != Socks4ReplyVN ||
s.version == Socks5 && socksVer != Socks5Version || s.version == SocksInvalid {
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return utils.LSMActionCancel
}
if socksVer == Socks4ReplyVN {
s.respLSM.AppendSteps(
s.parseSocks4RespPacket,
)
} else {
s.respLSM.AppendSteps(
s.parseSocks5RespMethod,
s.parseSocks5RespAuth,
s.parseSocks5RespConnInfo,
)
}
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return utils.LSMActionNext
}
func (s *socksStream) parseSocks5ReqMethod() utils.LSMAction {
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nMethods, ok := s.reqBuf.GetByte(false)
if !ok {
return utils.LSMActionPause
}
methods, ok := s.reqBuf.Get(int(nMethods)+1, true)
if !ok {
return utils.LSMActionPause
}
// For convenience, we only take the first method we can process
s.authReqMethod = Socks5AuthNoMatchingMethod
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for _, method := range methods[1:] {
switch method {
case Socks5AuthNotRequired:
s.authReqMethod = Socks5AuthNotRequired
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break
case Socks5AuthPassword:
s.authReqMethod = Socks5AuthPassword
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break
default:
// TODO: more auth method to support
}
}
return utils.LSMActionNext
}
func (s *socksStream) parseSocks5ReqAuth() utils.LSMAction {
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switch s.authReqMethod {
case Socks5AuthNotRequired:
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s.reqMap["auth"] = analyzer.PropMap{"method": s.authReqMethod}
case Socks5AuthPassword:
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meta, ok := s.reqBuf.Get(2, false)
if !ok {
return utils.LSMActionPause
}
if meta[0] != 0x01 {
return utils.LSMActionCancel
}
usernameLen := int(meta[1])
meta, ok = s.reqBuf.Get(usernameLen+3, false)
if !ok {
return utils.LSMActionPause
}
passwordLen := int(meta[usernameLen+2])
meta, ok = s.reqBuf.Get(usernameLen+passwordLen+3, true)
if !ok {
return utils.LSMActionPause
}
s.authUsername = string(meta[2 : usernameLen+2])
s.authPassword = string(meta[usernameLen+3:])
s.reqMap["auth"] = analyzer.PropMap{
"method": s.authReqMethod,
"username": s.authUsername,
"password": s.authPassword,
}
default:
return utils.LSMActionCancel
}
s.reqUpdated = true
return utils.LSMActionNext
}
func (s *socksStream) parseSocks5ReqConnInfo() utils.LSMAction {
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/* preInfo struct
+----+-----+-------+------+-------------+
|VER | CMD | RSV | ATYP | DST.ADDR(1) |
+----+-----+-------+------+-------------+
*/
preInfo, ok := s.reqBuf.Get(5, false)
if !ok {
return utils.LSMActionPause
}
// verify socks version
if preInfo[0] != Socks5Version {
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return utils.LSMActionCancel
}
var pktLen int
switch int(preInfo[3]) {
case Socks5AddrTypeIPv4:
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pktLen = 10
case Socks5AddrTypeDomain:
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domainLen := int(preInfo[4])
pktLen = 7 + domainLen
case Socks5AddrTypeIPv6:
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pktLen = 22
default:
return utils.LSMActionCancel
}
pkt, ok := s.reqBuf.Get(pktLen, true)
if !ok {
return utils.LSMActionPause
}
// parse cmd
cmd := int(pkt[1])
if cmd != Socks5CmdTCPConnect && cmd != Socks5CmdTCPBind && cmd != Socks5CmdUDPAssociate {
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return utils.LSMActionCancel
}
s.reqMap["cmd"] = cmd
// parse addr type
addrType := int(pkt[3])
var addr string
switch addrType {
case Socks5AddrTypeIPv4:
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addr = net.IPv4(pkt[4], pkt[5], pkt[6], pkt[7]).String()
case Socks5AddrTypeDomain:
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addr = string(pkt[5 : 5+pkt[4]])
case Socks5AddrTypeIPv6:
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addr = net.IP(pkt[4 : 4+net.IPv6len]).String()
default:
return utils.LSMActionCancel
}
s.reqMap["addr_type"] = addrType
s.reqMap["addr"] = addr
// parse port
port := int(pkt[pktLen-2])<<8 | int(pkt[pktLen-1])
s.reqMap["port"] = port
s.reqUpdated = true
return utils.LSMActionNext
}
func (s *socksStream) parseSocks5RespMethod() utils.LSMAction {
method, ok := s.respBuf.Get(1, true)
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if !ok {
return utils.LSMActionPause
}
s.authRespMethod = int(method[0])
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s.respMap = make(analyzer.PropMap)
return utils.LSMActionNext
}
func (s *socksStream) parseSocks5RespAuth() utils.LSMAction {
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switch s.authRespMethod {
case Socks5AuthNotRequired:
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s.respMap["auth"] = analyzer.PropMap{"method": s.authRespMethod}
case Socks5AuthPassword:
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authResp, ok := s.respBuf.Get(2, true)
if !ok {
return utils.LSMActionPause
}
if authResp[0] != 0x01 {
return utils.LSMActionCancel
}
authStatus := int(authResp[1])
s.respMap["auth"] = analyzer.PropMap{
"method": s.authRespMethod,
"status": authStatus,
}
default:
return utils.LSMActionCancel
}
s.respUpdated = true
return utils.LSMActionNext
}
func (s *socksStream) parseSocks5RespConnInfo() utils.LSMAction {
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/* preInfo struct
+----+-----+-------+------+-------------+
|VER | REP | RSV | ATYP | BND.ADDR(1) |
+----+-----+-------+------+-------------+
*/
preInfo, ok := s.respBuf.Get(5, false)
if !ok {
return utils.LSMActionPause
}
// verify socks version
if preInfo[0] != Socks5Version {
return utils.LSMActionCancel
}
var pktLen int
switch int(preInfo[3]) {
case Socks5AddrTypeIPv4:
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pktLen = 10
case Socks5AddrTypeDomain:
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domainLen := int(preInfo[4])
pktLen = 7 + domainLen
case Socks5AddrTypeIPv6:
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pktLen = 22
default:
return utils.LSMActionCancel
}
pkt, ok := s.respBuf.Get(pktLen, true)
if !ok {
return utils.LSMActionPause
}
// parse rep
rep := int(pkt[1])
s.respMap["rep"] = rep
// parse addr type
addrType := int(pkt[3])
var addr string
switch addrType {
case Socks5AddrTypeIPv4:
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addr = net.IPv4(pkt[4], pkt[5], pkt[6], pkt[7]).String()
case Socks5AddrTypeDomain:
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addr = string(pkt[5 : 5+pkt[4]])
case Socks5AddrTypeIPv6:
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addr = net.IP(pkt[4 : 4+net.IPv6len]).String()
default:
return utils.LSMActionCancel
}
s.respMap["addr_type"] = addrType
s.respMap["addr"] = addr
// parse port
port := int(pkt[pktLen-2])<<8 | int(pkt[pktLen-1])
s.respMap["port"] = port
s.respUpdated = true
return utils.LSMActionNext
}
func (s *socksStream) parseSocks4ReqIpAndPort() utils.LSMAction {
/* Following field will be parsed in this state:
+-----+----------+--------+
| CMD | DST.PORT | DST.IP |
+-----+----------+--------+
*/
pkt, ok := s.reqBuf.Get(7, true)
if !ok {
return utils.LSMActionPause
}
if pkt[0] != Socks4CmdTCPConnect && pkt[0] != Socks4CmdTCPBind {
return utils.LSMActionCancel
}
dstPort := uint16(pkt[1])<<8 | uint16(pkt[2])
dstIp := net.IPv4(pkt[3], pkt[4], pkt[5], pkt[6]).String()
// Socks4a extension
if pkt[3] == 0 && pkt[4] == 0 && pkt[5] == 0 {
s.version = Socks4A
}
s.reqMap["cmd"] = pkt[0]
s.reqMap["addr"] = dstIp
s.reqMap["addr_type"] = Socks5AddrTypeIPv4
s.reqMap["port"] = dstPort
s.reqUpdated = true
return utils.LSMActionNext
}
func (s *socksStream) parseSocks4ReqUserId() utils.LSMAction {
userIdSlice, ok := s.reqBuf.GetUntil([]byte("\x00"), true, true)
if !ok {
return utils.LSMActionPause
}
userId := string(userIdSlice[:len(userIdSlice)-1])
s.reqMap["auth"] = analyzer.PropMap{
"user_id": userId,
}
s.reqUpdated = true
return utils.LSMActionNext
}
func (s *socksStream) parseSocks4ReqHostname() utils.LSMAction {
// Only Socks4a support hostname
if s.version != Socks4A {
return utils.LSMActionNext
}
hostnameSlice, ok := s.reqBuf.GetUntil([]byte("\x00"), true, true)
if !ok {
return utils.LSMActionPause
}
hostname := string(hostnameSlice[:len(hostnameSlice)-1])
s.reqMap["addr"] = hostname
s.reqMap["addr_type"] = Socks5AddrTypeDomain
s.reqUpdated = true
return utils.LSMActionNext
}
func (s *socksStream) parseSocks4RespPacket() utils.LSMAction {
pkt, ok := s.respBuf.Get(7, true)
if !ok {
return utils.LSMActionPause
}
if pkt[0] != Socks4ReqGranted &&
pkt[0] != Socks4ReqRejectOrFailed &&
pkt[0] != Socks4ReqRejectIdentd &&
pkt[0] != Socks4ReqRejectUser {
return utils.LSMActionCancel
}
dstPort := uint16(pkt[1])<<8 | uint16(pkt[2])
dstIp := net.IPv4(pkt[3], pkt[4], pkt[5], pkt[6]).String()
s.respMap = analyzer.PropMap{
"rep": pkt[0],
"addr": dstIp,
"addr_type": Socks5AddrTypeIPv4,
"port": dstPort,
}
s.respUpdated = true
return utils.LSMActionNext
}
func (s *socksStream) socksVersion() int {
switch s.version {
case Socks4, Socks4A:
return Socks4Version
case Socks5:
return Socks5Version
default:
return SocksInvalid
}
}