mirror of
https://github.com/apernet/OpenGFW.git
synced 2024-11-13 13:59:24 +08:00
385 lines
8.6 KiB
Go
385 lines
8.6 KiB
Go
package udp
|
|
|
|
import (
|
|
"github.com/apernet/OpenGFW/analyzer"
|
|
"github.com/apernet/OpenGFW/analyzer/utils"
|
|
)
|
|
|
|
var (
|
|
_ analyzer.UDPAnalyzer = (*OpenVpnAnalyzer)(nil)
|
|
_ analyzer.TCPAnalyzer = (*OpenVpnAnalyzer)(nil)
|
|
)
|
|
|
|
var (
|
|
_ analyzer.UDPStream = (*openVpnUdpStream)(nil)
|
|
_ analyzer.TCPStream = (*openVpnTcpStream)(nil)
|
|
)
|
|
|
|
// Ref paper:
|
|
// https://www.usenix.org/system/files/sec22fall_xue-diwen.pdf
|
|
|
|
// OpenVPN Opcodes definitions from:
|
|
// https://github.com/OpenVPN/openvpn/blob/master/src/openvpn/ssl_pkt.h
|
|
const (
|
|
OpenVpnControlHardResetClientV1 = 1
|
|
OpenVpnControlHardResetServerV1 = 2
|
|
OpenVpnControlSoftResetV1 = 3
|
|
OpenVpnControlV1 = 4
|
|
OpenVpnAckV1 = 5
|
|
OpenVpnDataV1 = 6
|
|
OpenVpnControlHardResetClientV2 = 7
|
|
OpenVpnControlHardResetServerV2 = 8
|
|
OpenVpnDataV2 = 9
|
|
OpenVpnControlHardResetClientV3 = 10
|
|
OpenVpnControlWkcV1 = 11
|
|
)
|
|
|
|
const (
|
|
OpenVpnMinPktLen = 6
|
|
OpenVpnTcpPktDefaultLimit = 256
|
|
OpenVpnUdpPktDefaultLimit = 256
|
|
)
|
|
|
|
type OpenVpnAnalyzer struct{}
|
|
|
|
func (a *OpenVpnAnalyzer) Name() string {
|
|
return "openvpn"
|
|
}
|
|
|
|
func (a *OpenVpnAnalyzer) Limit() int {
|
|
return 0
|
|
}
|
|
|
|
func (a *OpenVpnAnalyzer) NewUDP(info analyzer.UDPInfo, logger analyzer.Logger) analyzer.UDPStream {
|
|
return newOpenVpnUdpStream(logger)
|
|
}
|
|
|
|
func (a *OpenVpnAnalyzer) NewTCP(info analyzer.TCPInfo, logger analyzer.Logger) analyzer.TCPStream {
|
|
return newOpenVpnTcpStream(logger)
|
|
}
|
|
|
|
type openVpnPkt struct {
|
|
pktLen uint16 // 16 bits, TCP proto only
|
|
opcode byte // 5 bits
|
|
_keyId byte // 3 bits, not used
|
|
|
|
// We don't care about the rest of the packet
|
|
// payload []byte
|
|
}
|
|
|
|
type openVpnStream struct {
|
|
logger analyzer.Logger
|
|
|
|
reqUpdated bool
|
|
reqLSM *utils.LinearStateMachine
|
|
reqDone bool
|
|
|
|
respUpdated bool
|
|
respLSM *utils.LinearStateMachine
|
|
respDone bool
|
|
|
|
rxPktCnt int
|
|
txPktCnt int
|
|
pktLimit int
|
|
|
|
reqPktParse func() (*openVpnPkt, utils.LSMAction)
|
|
respPktParse func() (*openVpnPkt, utils.LSMAction)
|
|
|
|
lastOpcode byte
|
|
}
|
|
|
|
func (o *openVpnStream) parseCtlHardResetClient() utils.LSMAction {
|
|
pkt, action := o.reqPktParse()
|
|
if action != utils.LSMActionNext {
|
|
return action
|
|
}
|
|
|
|
if pkt.opcode != OpenVpnControlHardResetClientV1 &&
|
|
pkt.opcode != OpenVpnControlHardResetClientV2 &&
|
|
pkt.opcode != OpenVpnControlHardResetClientV3 {
|
|
return utils.LSMActionCancel
|
|
}
|
|
o.lastOpcode = pkt.opcode
|
|
|
|
return utils.LSMActionNext
|
|
}
|
|
|
|
func (o *openVpnStream) parseCtlHardResetServer() utils.LSMAction {
|
|
if o.lastOpcode != OpenVpnControlHardResetClientV1 &&
|
|
o.lastOpcode != OpenVpnControlHardResetClientV2 &&
|
|
o.lastOpcode != OpenVpnControlHardResetClientV3 {
|
|
return utils.LSMActionCancel
|
|
}
|
|
|
|
pkt, action := o.respPktParse()
|
|
if action != utils.LSMActionNext {
|
|
return action
|
|
}
|
|
|
|
if pkt.opcode != OpenVpnControlHardResetServerV1 &&
|
|
pkt.opcode != OpenVpnControlHardResetServerV2 {
|
|
return utils.LSMActionCancel
|
|
}
|
|
o.lastOpcode = pkt.opcode
|
|
|
|
return utils.LSMActionNext
|
|
}
|
|
|
|
func (o *openVpnStream) parseReq() utils.LSMAction {
|
|
pkt, action := o.reqPktParse()
|
|
if action != utils.LSMActionNext {
|
|
return action
|
|
}
|
|
|
|
if pkt.opcode != OpenVpnControlSoftResetV1 &&
|
|
pkt.opcode != OpenVpnControlV1 &&
|
|
pkt.opcode != OpenVpnAckV1 &&
|
|
pkt.opcode != OpenVpnDataV1 &&
|
|
pkt.opcode != OpenVpnDataV2 &&
|
|
pkt.opcode != OpenVpnControlWkcV1 {
|
|
return utils.LSMActionCancel
|
|
}
|
|
|
|
o.txPktCnt += 1
|
|
o.reqUpdated = true
|
|
|
|
return utils.LSMActionPause
|
|
}
|
|
|
|
func (o *openVpnStream) parseResp() utils.LSMAction {
|
|
pkt, action := o.respPktParse()
|
|
if action != utils.LSMActionNext {
|
|
return action
|
|
}
|
|
|
|
if pkt.opcode != OpenVpnControlSoftResetV1 &&
|
|
pkt.opcode != OpenVpnControlV1 &&
|
|
pkt.opcode != OpenVpnAckV1 &&
|
|
pkt.opcode != OpenVpnDataV1 &&
|
|
pkt.opcode != OpenVpnDataV2 &&
|
|
pkt.opcode != OpenVpnControlWkcV1 {
|
|
return utils.LSMActionCancel
|
|
}
|
|
|
|
o.rxPktCnt += 1
|
|
o.respUpdated = true
|
|
|
|
return utils.LSMActionPause
|
|
}
|
|
|
|
type openVpnUdpStream struct {
|
|
openVpnStream
|
|
curPkt []byte
|
|
// We don't introduce `invalidCount` here to decrease the false positive rate
|
|
// invalidCount int
|
|
}
|
|
|
|
func newOpenVpnUdpStream(logger analyzer.Logger) *openVpnUdpStream {
|
|
s := &openVpnUdpStream{
|
|
openVpnStream: openVpnStream{
|
|
logger: logger,
|
|
pktLimit: OpenVpnUdpPktDefaultLimit,
|
|
},
|
|
}
|
|
s.respPktParse = s.parsePkt
|
|
s.reqPktParse = s.parsePkt
|
|
s.reqLSM = utils.NewLinearStateMachine(
|
|
s.parseCtlHardResetClient,
|
|
s.parseReq,
|
|
)
|
|
s.respLSM = utils.NewLinearStateMachine(
|
|
s.parseCtlHardResetServer,
|
|
s.parseResp,
|
|
)
|
|
return s
|
|
}
|
|
|
|
func (o *openVpnUdpStream) Feed(rev bool, data []byte) (u *analyzer.PropUpdate, d bool) {
|
|
if len(data) == 0 {
|
|
return nil, false
|
|
}
|
|
var update *analyzer.PropUpdate
|
|
var cancelled bool
|
|
o.curPkt = data
|
|
if rev {
|
|
o.respUpdated = false
|
|
cancelled, o.respDone = o.respLSM.Run()
|
|
if o.respUpdated {
|
|
update = &analyzer.PropUpdate{
|
|
Type: analyzer.PropUpdateMerge,
|
|
M: analyzer.PropMap{"rx_pkt_cnt": o.rxPktCnt},
|
|
}
|
|
o.respUpdated = false
|
|
}
|
|
} else {
|
|
o.reqUpdated = false
|
|
cancelled, o.reqDone = o.reqLSM.Run()
|
|
if o.reqUpdated {
|
|
update = &analyzer.PropUpdate{
|
|
Type: analyzer.PropUpdateMerge,
|
|
M: analyzer.PropMap{"tx_pkt_cnt": o.txPktCnt},
|
|
}
|
|
o.reqUpdated = false
|
|
}
|
|
}
|
|
|
|
return update, cancelled || (o.reqDone && o.respDone) || o.rxPktCnt+o.txPktCnt > o.pktLimit
|
|
}
|
|
|
|
func (o *openVpnUdpStream) Close(limited bool) *analyzer.PropUpdate {
|
|
return nil
|
|
}
|
|
|
|
// Parse OpenVpn UDP packet.
|
|
func (o *openVpnUdpStream) parsePkt() (p *openVpnPkt, action utils.LSMAction) {
|
|
if o.curPkt == nil {
|
|
return nil, utils.LSMActionPause
|
|
}
|
|
|
|
if !OpenVpnCheckForValidOpcode(o.curPkt[0] >> 3) {
|
|
return nil, utils.LSMActionCancel
|
|
}
|
|
|
|
// Parse packet header
|
|
p = &openVpnPkt{}
|
|
p.opcode = o.curPkt[0] >> 3
|
|
p._keyId = o.curPkt[0] & 0x07
|
|
|
|
o.curPkt = nil
|
|
return p, utils.LSMActionNext
|
|
}
|
|
|
|
type openVpnTcpStream struct {
|
|
openVpnStream
|
|
reqBuf *utils.ByteBuffer
|
|
respBuf *utils.ByteBuffer
|
|
}
|
|
|
|
func newOpenVpnTcpStream(logger analyzer.Logger) *openVpnTcpStream {
|
|
s := &openVpnTcpStream{
|
|
openVpnStream: openVpnStream{
|
|
logger: logger,
|
|
pktLimit: OpenVpnTcpPktDefaultLimit,
|
|
},
|
|
reqBuf: &utils.ByteBuffer{},
|
|
respBuf: &utils.ByteBuffer{},
|
|
}
|
|
s.respPktParse = func() (*openVpnPkt, utils.LSMAction) {
|
|
return s.parsePkt(true)
|
|
}
|
|
s.reqPktParse = func() (*openVpnPkt, utils.LSMAction) {
|
|
return s.parsePkt(false)
|
|
}
|
|
s.reqLSM = utils.NewLinearStateMachine(
|
|
s.parseCtlHardResetClient,
|
|
s.parseReq,
|
|
)
|
|
s.respLSM = utils.NewLinearStateMachine(
|
|
s.parseCtlHardResetServer,
|
|
s.parseResp,
|
|
)
|
|
return s
|
|
}
|
|
|
|
func (o *openVpnTcpStream) Feed(rev, start, end bool, skip int, data []byte) (u *analyzer.PropUpdate, d bool) {
|
|
if skip != 0 {
|
|
return nil, true
|
|
}
|
|
if len(data) == 0 {
|
|
return nil, false
|
|
}
|
|
var update *analyzer.PropUpdate
|
|
var cancelled bool
|
|
if rev {
|
|
o.respBuf.Append(data)
|
|
o.respUpdated = false
|
|
cancelled, o.respDone = o.respLSM.Run()
|
|
if o.respUpdated {
|
|
update = &analyzer.PropUpdate{
|
|
Type: analyzer.PropUpdateMerge,
|
|
M: analyzer.PropMap{"rx_pkt_cnt": o.rxPktCnt},
|
|
}
|
|
o.respUpdated = false
|
|
}
|
|
} else {
|
|
o.reqBuf.Append(data)
|
|
o.reqUpdated = false
|
|
cancelled, o.reqDone = o.reqLSM.Run()
|
|
if o.reqUpdated {
|
|
update = &analyzer.PropUpdate{
|
|
Type: analyzer.PropUpdateMerge,
|
|
M: analyzer.PropMap{"tx_pkt_cnt": o.txPktCnt},
|
|
}
|
|
o.reqUpdated = false
|
|
}
|
|
}
|
|
|
|
return update, cancelled || (o.reqDone && o.respDone) || o.rxPktCnt+o.txPktCnt > o.pktLimit
|
|
}
|
|
|
|
func (o *openVpnTcpStream) Close(limited bool) *analyzer.PropUpdate {
|
|
o.reqBuf.Reset()
|
|
o.respBuf.Reset()
|
|
return nil
|
|
}
|
|
|
|
// Parse OpenVpn TCP packet.
|
|
func (o *openVpnTcpStream) parsePkt(rev bool) (p *openVpnPkt, action utils.LSMAction) {
|
|
var buffer *utils.ByteBuffer
|
|
if rev {
|
|
buffer = o.respBuf
|
|
} else {
|
|
buffer = o.reqBuf
|
|
}
|
|
|
|
// Parse packet length
|
|
pktLen, ok := buffer.GetUint16(false, false)
|
|
if !ok {
|
|
return nil, utils.LSMActionPause
|
|
}
|
|
|
|
if pktLen < OpenVpnMinPktLen {
|
|
return nil, utils.LSMActionCancel
|
|
}
|
|
|
|
pktOp, ok := buffer.Get(3, false)
|
|
if !ok {
|
|
return nil, utils.LSMActionPause
|
|
}
|
|
if !OpenVpnCheckForValidOpcode(pktOp[2] >> 3) {
|
|
return nil, utils.LSMActionCancel
|
|
}
|
|
|
|
pkt, ok := buffer.Get(int(pktLen)+2, true)
|
|
if !ok {
|
|
return nil, utils.LSMActionPause
|
|
}
|
|
pkt = pkt[2:]
|
|
|
|
// Parse packet header
|
|
p = &openVpnPkt{}
|
|
p.pktLen = pktLen
|
|
p.opcode = pkt[0] >> 3
|
|
p._keyId = pkt[0] & 0x07
|
|
|
|
return p, utils.LSMActionNext
|
|
}
|
|
|
|
func OpenVpnCheckForValidOpcode(opcode byte) bool {
|
|
switch opcode {
|
|
case OpenVpnControlHardResetClientV1,
|
|
OpenVpnControlHardResetServerV1,
|
|
OpenVpnControlSoftResetV1,
|
|
OpenVpnControlV1,
|
|
OpenVpnAckV1,
|
|
OpenVpnDataV1,
|
|
OpenVpnControlHardResetClientV2,
|
|
OpenVpnControlHardResetServerV2,
|
|
OpenVpnDataV2,
|
|
OpenVpnControlHardResetClientV3,
|
|
OpenVpnControlWkcV1:
|
|
return true
|
|
}
|
|
return false
|
|
}
|