mirror of
https://github.com/apernet/OpenGFW.git
synced 2024-11-13 13:59:24 +08:00
355 lines
9.3 KiB
Go
355 lines
9.3 KiB
Go
package tcp
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import (
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"github.com/apernet/OpenGFW/analyzer"
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"github.com/apernet/OpenGFW/analyzer/utils"
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)
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var _ analyzer.TCPAnalyzer = (*TLSAnalyzer)(nil)
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type TLSAnalyzer struct{}
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func (a *TLSAnalyzer) Name() string {
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return "tls"
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}
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func (a *TLSAnalyzer) Limit() int {
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return 8192
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}
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func (a *TLSAnalyzer) NewTCP(info analyzer.TCPInfo, logger analyzer.Logger) analyzer.TCPStream {
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return newTLSStream(logger)
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}
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type tlsStream struct {
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logger analyzer.Logger
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reqBuf *utils.ByteBuffer
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reqMap analyzer.PropMap
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reqUpdated bool
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reqLSM *utils.LinearStateMachine
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reqDone bool
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respBuf *utils.ByteBuffer
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respMap analyzer.PropMap
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respUpdated bool
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respLSM *utils.LinearStateMachine
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respDone bool
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clientHelloLen int
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serverHelloLen int
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}
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func newTLSStream(logger analyzer.Logger) *tlsStream {
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s := &tlsStream{logger: logger, reqBuf: &utils.ByteBuffer{}, respBuf: &utils.ByteBuffer{}}
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s.reqLSM = utils.NewLinearStateMachine(
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s.tlsClientHelloSanityCheck,
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s.parseClientHello,
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)
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s.respLSM = utils.NewLinearStateMachine(
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s.tlsServerHelloSanityCheck,
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s.parseServerHello,
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)
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return s
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}
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func (s *tlsStream) Feed(rev, start, end bool, skip int, data []byte) (u *analyzer.PropUpdate, done bool) {
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if skip != 0 {
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return nil, true
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}
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if len(data) == 0 {
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return nil, false
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}
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var update *analyzer.PropUpdate
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var cancelled bool
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if rev {
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s.respBuf.Append(data)
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s.respUpdated = false
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cancelled, s.respDone = s.respLSM.Run()
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if s.respUpdated {
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update = &analyzer.PropUpdate{
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Type: analyzer.PropUpdateMerge,
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M: analyzer.PropMap{"resp": s.respMap},
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}
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s.respUpdated = false
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}
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} else {
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s.reqBuf.Append(data)
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s.reqUpdated = false
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cancelled, s.reqDone = s.reqLSM.Run()
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if s.reqUpdated {
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update = &analyzer.PropUpdate{
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Type: analyzer.PropUpdateMerge,
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M: analyzer.PropMap{"req": s.reqMap},
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}
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s.reqUpdated = false
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}
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}
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return update, cancelled || (s.reqDone && s.respDone)
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}
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func (s *tlsStream) tlsClientHelloSanityCheck() utils.LSMAction {
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data, ok := s.reqBuf.Get(9, true)
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if !ok {
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return utils.LSMActionPause
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}
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if data[0] != 0x16 || data[5] != 0x01 {
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// Not a TLS handshake, or not a client hello
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return utils.LSMActionCancel
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}
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s.clientHelloLen = int(data[6])<<16 | int(data[7])<<8 | int(data[8])
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if s.clientHelloLen < 41 {
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// 2 (Protocol Version) +
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// 32 (Random) +
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// 1 (Session ID Length) +
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// 2 (Cipher Suites Length) +_ws.col.protocol == "TLSv1.3"
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// 2 (Cipher Suite) +
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// 1 (Compression Methods Length) +
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// 1 (Compression Method) +
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// No extensions
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// This should be the bare minimum for a client hello
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return utils.LSMActionCancel
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}
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return utils.LSMActionNext
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}
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func (s *tlsStream) tlsServerHelloSanityCheck() utils.LSMAction {
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data, ok := s.respBuf.Get(9, true)
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if !ok {
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return utils.LSMActionPause
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}
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if data[0] != 0x16 || data[5] != 0x02 {
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// Not a TLS handshake, or not a server hello
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return utils.LSMActionCancel
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}
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s.serverHelloLen = int(data[6])<<16 | int(data[7])<<8 | int(data[8])
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if s.serverHelloLen < 38 {
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// 2 (Protocol Version) +
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// 32 (Random) +
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// 1 (Session ID Length) +
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// 2 (Cipher Suite) +
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// 1 (Compression Method) +
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// No extensions
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// This should be the bare minimum for a server hello
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return utils.LSMActionCancel
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}
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return utils.LSMActionNext
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}
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func (s *tlsStream) parseClientHello() utils.LSMAction {
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chBuf, ok := s.reqBuf.GetSubBuffer(s.clientHelloLen, true)
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if !ok {
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// Not a full client hello yet
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return utils.LSMActionPause
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}
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s.reqUpdated = true
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s.reqMap = make(analyzer.PropMap)
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// Version, random & session ID length combined are within 35 bytes,
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// so no need for bounds checking
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s.reqMap["version"], _ = chBuf.GetUint16(false, true)
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s.reqMap["random"], _ = chBuf.Get(32, true)
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sessionIDLen, _ := chBuf.GetByte(true)
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s.reqMap["session"], ok = chBuf.Get(int(sessionIDLen), true)
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if !ok {
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// Not enough data for session ID
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return utils.LSMActionCancel
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}
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cipherSuitesLen, ok := chBuf.GetUint16(false, true)
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if !ok {
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// Not enough data for cipher suites length
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return utils.LSMActionCancel
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}
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if cipherSuitesLen%2 != 0 {
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// Cipher suites are 2 bytes each, so must be even
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return utils.LSMActionCancel
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}
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ciphers := make([]uint16, cipherSuitesLen/2)
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for i := range ciphers {
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ciphers[i], ok = chBuf.GetUint16(false, true)
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if !ok {
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return utils.LSMActionCancel
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}
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}
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s.reqMap["ciphers"] = ciphers
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compressionMethodsLen, ok := chBuf.GetByte(true)
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if !ok {
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// Not enough data for compression methods length
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return utils.LSMActionCancel
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}
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// Compression methods are 1 byte each, we just put a byte slice here
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s.reqMap["compression"], ok = chBuf.Get(int(compressionMethodsLen), true)
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if !ok {
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// Not enough data for compression methods
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return utils.LSMActionCancel
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}
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extsLen, ok := chBuf.GetUint16(false, true)
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if !ok {
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// No extensions, I guess it's possible?
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return utils.LSMActionNext
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}
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extBuf, ok := chBuf.GetSubBuffer(int(extsLen), true)
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if !ok {
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// Not enough data for extensions
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return utils.LSMActionCancel
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}
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for extBuf.Len() > 0 {
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extType, ok := extBuf.GetUint16(false, true)
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if !ok {
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// Not enough data for extension type
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return utils.LSMActionCancel
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}
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extLen, ok := extBuf.GetUint16(false, true)
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if !ok {
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// Not enough data for extension length
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return utils.LSMActionCancel
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}
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extDataBuf, ok := extBuf.GetSubBuffer(int(extLen), true)
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if !ok || !s.handleExtensions(extType, extDataBuf, s.reqMap) {
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// Not enough data for extension data, or invalid extension
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return utils.LSMActionCancel
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}
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}
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return utils.LSMActionNext
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}
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func (s *tlsStream) parseServerHello() utils.LSMAction {
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shBuf, ok := s.respBuf.GetSubBuffer(s.serverHelloLen, true)
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if !ok {
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// Not a full server hello yet
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return utils.LSMActionPause
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}
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s.respUpdated = true
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s.respMap = make(analyzer.PropMap)
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// Version, random & session ID length combined are within 35 bytes,
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// so no need for bounds checking
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s.respMap["version"], _ = shBuf.GetUint16(false, true)
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s.respMap["random"], _ = shBuf.Get(32, true)
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sessionIDLen, _ := shBuf.GetByte(true)
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s.respMap["session"], ok = shBuf.Get(int(sessionIDLen), true)
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if !ok {
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// Not enough data for session ID
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return utils.LSMActionCancel
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}
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cipherSuite, ok := shBuf.GetUint16(false, true)
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if !ok {
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// Not enough data for cipher suite
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return utils.LSMActionCancel
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}
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s.respMap["cipher"] = cipherSuite
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compressionMethod, ok := shBuf.GetByte(true)
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if !ok {
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// Not enough data for compression method
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return utils.LSMActionCancel
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}
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s.respMap["compression"] = compressionMethod
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extsLen, ok := shBuf.GetUint16(false, true)
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if !ok {
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// No extensions, I guess it's possible?
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return utils.LSMActionNext
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}
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extBuf, ok := shBuf.GetSubBuffer(int(extsLen), true)
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if !ok {
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// Not enough data for extensions
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return utils.LSMActionCancel
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}
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for extBuf.Len() > 0 {
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extType, ok := extBuf.GetUint16(false, true)
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if !ok {
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// Not enough data for extension type
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return utils.LSMActionCancel
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}
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extLen, ok := extBuf.GetUint16(false, true)
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if !ok {
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// Not enough data for extension length
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return utils.LSMActionCancel
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}
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extDataBuf, ok := extBuf.GetSubBuffer(int(extLen), true)
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if !ok || !s.handleExtensions(extType, extDataBuf, s.respMap) {
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// Not enough data for extension data, or invalid extension
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return utils.LSMActionCancel
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}
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}
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return utils.LSMActionNext
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}
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func (s *tlsStream) handleExtensions(extType uint16, extDataBuf *utils.ByteBuffer, m analyzer.PropMap) bool {
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switch extType {
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case 0x0000: // SNI
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ok := extDataBuf.Skip(2) // Ignore list length, we only care about the first entry for now
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if !ok {
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// Not enough data for list length
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return false
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}
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sniType, ok := extDataBuf.GetByte(true)
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if !ok || sniType != 0 {
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// Not enough data for SNI type, or not hostname
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return false
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}
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sniLen, ok := extDataBuf.GetUint16(false, true)
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if !ok {
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// Not enough data for SNI length
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return false
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}
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m["sni"], ok = extDataBuf.GetString(int(sniLen), true)
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if !ok {
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// Not enough data for SNI
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return false
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}
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case 0x0010: // ALPN
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ok := extDataBuf.Skip(2) // Ignore list length, as we read until the end
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if !ok {
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// Not enough data for list length
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return false
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}
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var alpnList []string
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for extDataBuf.Len() > 0 {
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alpnLen, ok := extDataBuf.GetByte(true)
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if !ok {
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// Not enough data for ALPN length
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return false
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}
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alpn, ok := extDataBuf.GetString(int(alpnLen), true)
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if !ok {
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// Not enough data for ALPN
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return false
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}
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alpnList = append(alpnList, alpn)
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}
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m["alpn"] = alpnList
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case 0x002b: // Supported Versions
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if extDataBuf.Len() == 2 {
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// Server only selects one version
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m["supported_versions"], _ = extDataBuf.GetUint16(false, true)
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} else {
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// Client sends a list of versions
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ok := extDataBuf.Skip(1) // Ignore list length, as we read until the end
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if !ok {
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// Not enough data for list length
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return false
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}
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var versions []uint16
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for extDataBuf.Len() > 0 {
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ver, ok := extDataBuf.GetUint16(false, true)
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if !ok {
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// Not enough data for version
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return false
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}
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versions = append(versions, ver)
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}
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m["supported_versions"] = versions
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}
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case 0xfe0d: // ECH
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// We can't parse ECH for now, just set a flag
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m["ech"] = true
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}
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return true
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}
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func (s *tlsStream) Close(limited bool) *analyzer.PropUpdate {
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s.reqBuf.Reset()
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s.respBuf.Reset()
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s.reqMap = nil
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s.respMap = nil
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return nil
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}
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