clash/transport/vless/filter.go

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package vless
import (
"bytes"
"encoding/binary"
"github.com/Dreamacro/clash/log"
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)
var (
tls13SupportedVersions = []byte{0x00, 0x2b, 0x00, 0x02, 0x03, 0x04}
tlsClientHandshakeStart = []byte{0x16, 0x03}
tlsServerHandshakeStart = []byte{0x16, 0x03, 0x03}
tlsApplicationDataStart = []byte{0x17, 0x03, 0x03}
tls13CipherSuiteMap = map[uint16]string{
0x1301: "TLS_AES_128_GCM_SHA256",
0x1302: "TLS_AES_256_GCM_SHA384",
0x1303: "TLS_CHACHA20_POLY1305_SHA256",
0x1304: "TLS_AES_128_CCM_SHA256",
0x1305: "TLS_AES_128_CCM_8_SHA256",
}
)
const (
tlsHandshakeTypeClientHello byte = 0x01
tlsHandshakeTypeServerHello byte = 0x02
)
func (vc *Conn) FilterTLS(buffer []byte) (index int) {
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if vc.packetsToFilter <= 0 {
return 0
}
lenP := len(buffer)
vc.packetsToFilter--
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if index = bytes.Index(buffer, tlsServerHandshakeStart); index != -1 {
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if lenP > index+5 {
if buffer[0] == 22 && buffer[1] == 3 && buffer[2] == 3 {
vc.isTLS = true
if buffer[5] == tlsHandshakeTypeServerHello {
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//log.Debugln("isTLS12orAbove")
vc.remainingServerHello = binary.BigEndian.Uint16(buffer[index+3:]) + 5
vc.isTLS12orAbove = true
if lenP-index >= 79 && vc.remainingServerHello >= 79 {
sessionIDLen := int(buffer[index+43])
vc.cipher = binary.BigEndian.Uint16(buffer[index+43+sessionIDLen+1:])
}
}
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}
}
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} else if index = bytes.Index(buffer, tlsClientHandshakeStart); index != -1 {
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if lenP > index+5 && buffer[index+5] == tlsHandshakeTypeClientHello {
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vc.isTLS = true
}
}
if vc.remainingServerHello > 0 {
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end := int(vc.remainingServerHello)
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i := index
if i < 0 {
i = 0
}
if i+end > lenP {
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end = lenP
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vc.remainingServerHello -= uint16(end - i)
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} else {
vc.remainingServerHello -= uint16(end)
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end += i
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}
if bytes.Contains(buffer[i:end], tls13SupportedVersions) {
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// TLS 1.3 Client Hello
cs, ok := tls13CipherSuiteMap[vc.cipher]
if ok && cs != "TLS_AES_128_CCM_8_SHA256" {
vc.enableXTLS = true
}
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log.Debugln("XTLS Vision found TLS 1.3, packetLength=%d CipherSuite=%s", lenP, cs)
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vc.packetsToFilter = 0
return
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} else if vc.remainingServerHello <= 0 {
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log.Debugln("XTLS Vision found TLS 1.2, packetLength=%d", lenP)
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vc.packetsToFilter = 0
return
}
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log.Debugln("XTLS Vision found inconclusive server hello, packetLength=%d, remainingServerHelloBytes=%d", lenP, vc.remainingServerHello)
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}
if vc.packetsToFilter <= 0 {
log.Debugln("XTLS Vision stop filtering")
}
return
}