sing-box/transport/clashssr/protocol/auth_sha1_v4.go

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package protocol
import (
"bytes"
"encoding/binary"
"hash/adler32"
"hash/crc32"
"math/rand"
"net"
"github.com/Dreamacro/clash/common/pool"
"github.com/Dreamacro/clash/transport/ssr/tools"
)
func init() {
register("auth_sha1_v4", newAuthSHA1V4, 7)
}
type authSHA1V4 struct {
*Base
*authData
iv []byte
hasSentHeader bool
rawTrans bool
}
func newAuthSHA1V4(b *Base) Protocol {
return &authSHA1V4{Base: b, authData: &authData{}}
}
func (a *authSHA1V4) StreamConn(c net.Conn, iv []byte) net.Conn {
p := &authSHA1V4{Base: a.Base, authData: a.next()}
p.iv = iv
return &Conn{Conn: c, Protocol: p}
}
func (a *authSHA1V4) PacketConn(c net.PacketConn) net.PacketConn {
return c
}
func (a *authSHA1V4) Decode(dst, src *bytes.Buffer) error {
if a.rawTrans {
dst.ReadFrom(src)
return nil
}
for src.Len() > 4 {
if uint16(crc32.ChecksumIEEE(src.Bytes()[:2])&0xffff) != binary.LittleEndian.Uint16(src.Bytes()[2:4]) {
src.Reset()
return errAuthSHA1V4CRC32Error
}
length := int(binary.BigEndian.Uint16(src.Bytes()[:2]))
if length >= 8192 || length < 7 {
a.rawTrans = true
src.Reset()
return errAuthSHA1V4LengthError
}
if length > src.Len() {
break
}
if adler32.Checksum(src.Bytes()[:length-4]) != binary.LittleEndian.Uint32(src.Bytes()[length-4:length]) {
a.rawTrans = true
src.Reset()
return errAuthSHA1V4Adler32Error
}
pos := int(src.Bytes()[4])
if pos < 255 {
pos += 4
} else {
pos = int(binary.BigEndian.Uint16(src.Bytes()[5:7])) + 4
}
dst.Write(src.Bytes()[pos : length-4])
src.Next(length)
}
return nil
}
func (a *authSHA1V4) Encode(buf *bytes.Buffer, b []byte) error {
if !a.hasSentHeader {
dataLength := getDataLength(b)
a.packAuthData(buf, b[:dataLength])
b = b[dataLength:]
a.hasSentHeader = true
}
for len(b) > 8100 {
a.packData(buf, b[:8100])
b = b[8100:]
}
if len(b) > 0 {
a.packData(buf, b)
}
return nil
}
func (a *authSHA1V4) DecodePacket(b []byte) ([]byte, error) { return b, nil }
func (a *authSHA1V4) EncodePacket(buf *bytes.Buffer, b []byte) error {
buf.Write(b)
return nil
}
func (a *authSHA1V4) packData(poolBuf *bytes.Buffer, data []byte) {
dataLength := len(data)
randDataLength := a.getRandDataLength(dataLength)
/*
2: uint16 BigEndian packedDataLength
2: uint16 LittleEndian crc32Data & 0xffff
3: maxRandDataLengthPrefix (min:1)
4: adler32Data
*/
packedDataLength := 2 + 2 + 3 + randDataLength + dataLength + 4
if randDataLength < 128 {
packedDataLength -= 2
}
binary.Write(poolBuf, binary.BigEndian, uint16(packedDataLength))
binary.Write(poolBuf, binary.LittleEndian, uint16(crc32.ChecksumIEEE(poolBuf.Bytes()[poolBuf.Len()-2:])&0xffff))
a.packRandData(poolBuf, randDataLength)
poolBuf.Write(data)
binary.Write(poolBuf, binary.LittleEndian, adler32.Checksum(poolBuf.Bytes()[poolBuf.Len()-packedDataLength+4:]))
}
func (a *authSHA1V4) packAuthData(poolBuf *bytes.Buffer, data []byte) {
dataLength := len(data)
randDataLength := a.getRandDataLength(12 + dataLength)
/*
2: uint16 BigEndian packedAuthDataLength
4: uint32 LittleEndian crc32Data
3: maxRandDataLengthPrefix (min: 1)
12: authDataLength
10: hmacSHA1DataLength
*/
packedAuthDataLength := 2 + 4 + 3 + randDataLength + 12 + dataLength + 10
if randDataLength < 128 {
packedAuthDataLength -= 2
}
salt := []byte("auth_sha1_v4")
crcData := pool.Get(len(salt) + len(a.Key) + 2)
defer pool.Put(crcData)
binary.BigEndian.PutUint16(crcData, uint16(packedAuthDataLength))
copy(crcData[2:], salt)
copy(crcData[2+len(salt):], a.Key)
key := pool.Get(len(a.iv) + len(a.Key))
defer pool.Put(key)
copy(key, a.iv)
copy(key[len(a.iv):], a.Key)
poolBuf.Write(crcData[:2])
binary.Write(poolBuf, binary.LittleEndian, crc32.ChecksumIEEE(crcData))
a.packRandData(poolBuf, randDataLength)
a.putAuthData(poolBuf)
poolBuf.Write(data)
poolBuf.Write(tools.HmacSHA1(key, poolBuf.Bytes()[poolBuf.Len()-packedAuthDataLength+10:])[:10])
}
func (a *authSHA1V4) packRandData(poolBuf *bytes.Buffer, size int) {
if size < 128 {
poolBuf.WriteByte(byte(size + 1))
tools.AppendRandBytes(poolBuf, size)
return
}
poolBuf.WriteByte(255)
binary.Write(poolBuf, binary.BigEndian, uint16(size+3))
tools.AppendRandBytes(poolBuf, size)
}
func (a *authSHA1V4) getRandDataLength(size int) int {
if size > 1200 {
return 0
}
if size > 400 {
return rand.Intn(256)
}
return rand.Intn(512)
}