2018-10-07 17:09:45 +00:00
|
|
|
package util
|
|
|
|
|
|
|
|
import (
|
|
|
|
"encoding/binary"
|
|
|
|
|
2018-10-20 20:41:01 +00:00
|
|
|
xxhash "github.com/OneOfOne/xxhash"
|
2018-10-07 17:09:45 +00:00
|
|
|
mux "github.com/cbeuw/Cloak/internal/multiplex"
|
|
|
|
)
|
|
|
|
|
2018-10-20 20:41:01 +00:00
|
|
|
func genXorKeys(SID []byte, data []byte) (i uint32, ii uint32, iii uint32) {
|
|
|
|
h := xxhash.New32()
|
|
|
|
ret := make([]uint32, 3)
|
|
|
|
preHash := make([]byte, 16)
|
|
|
|
for j := 0; j < 3; j++ {
|
|
|
|
copy(preHash[0:10], SID[j*10:j*10+10])
|
|
|
|
copy(preHash[10:16], data[j*6:j*6+6])
|
|
|
|
h.Write(preHash)
|
|
|
|
ret[j] = h.Sum32()
|
|
|
|
}
|
|
|
|
return ret[0], ret[1], ret[2]
|
2018-10-07 17:09:45 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
func MakeObfs(key []byte) func(*mux.Frame) []byte {
|
|
|
|
obfs := func(f *mux.Frame) []byte {
|
2018-10-20 20:41:01 +00:00
|
|
|
obfsedHeader := make([]byte, 12)
|
2018-10-07 17:09:45 +00:00
|
|
|
// header: [StreamID 4 bytes][Seq 4 bytes][ClosingStreamID 4 bytes]
|
2018-10-20 20:41:01 +00:00
|
|
|
i, ii, iii := genXorKeys(key, f.Payload[0:18])
|
|
|
|
binary.BigEndian.PutUint32(obfsedHeader[0:4], f.StreamID^i)
|
|
|
|
binary.BigEndian.PutUint32(obfsedHeader[4:8], f.Seq^ii)
|
|
|
|
binary.BigEndian.PutUint32(obfsedHeader[8:12], f.ClosingStreamID^iii)
|
2018-10-20 16:03:39 +00:00
|
|
|
|
|
|
|
// Composing final obfsed message
|
|
|
|
// We don't use util.AddRecordLayer here to avoid unnecessary malloc
|
2018-10-20 20:41:01 +00:00
|
|
|
obfsed := make([]byte, 5+12+len(f.Payload))
|
2018-10-20 16:03:39 +00:00
|
|
|
obfsed[0] = 0x17
|
|
|
|
obfsed[1] = 0x03
|
|
|
|
obfsed[2] = 0x03
|
2018-10-20 20:41:01 +00:00
|
|
|
binary.BigEndian.PutUint16(obfsed[3:5], uint16(12+len(f.Payload)))
|
|
|
|
copy(obfsed[5:17], obfsedHeader)
|
|
|
|
copy(obfsed[17:], f.Payload)
|
|
|
|
// obfsed: [record layer 5 bytes][cipherheader 12 bytes][payload]
|
2018-10-20 16:03:39 +00:00
|
|
|
return obfsed
|
2018-10-07 17:09:45 +00:00
|
|
|
}
|
|
|
|
return obfs
|
|
|
|
}
|
|
|
|
|
|
|
|
func MakeDeobfs(key []byte) func([]byte) *mux.Frame {
|
|
|
|
deobfs := func(in []byte) *mux.Frame {
|
2018-10-20 16:03:39 +00:00
|
|
|
peeled := in[5:]
|
2018-10-20 20:41:01 +00:00
|
|
|
i, ii, iii := genXorKeys(key, peeled[12:30])
|
|
|
|
streamID := binary.BigEndian.Uint32(peeled[0:4]) ^ i
|
|
|
|
seq := binary.BigEndian.Uint32(peeled[4:8]) ^ ii
|
|
|
|
closingStreamID := binary.BigEndian.Uint32(peeled[8:12]) ^ iii
|
|
|
|
payload := make([]byte, len(peeled)-12)
|
|
|
|
copy(payload, peeled[12:])
|
2018-10-07 17:09:45 +00:00
|
|
|
ret := &mux.Frame{
|
|
|
|
StreamID: streamID,
|
|
|
|
Seq: seq,
|
|
|
|
ClosingStreamID: closingStreamID,
|
|
|
|
Payload: payload,
|
|
|
|
}
|
|
|
|
return ret
|
|
|
|
}
|
|
|
|
return deobfs
|
|
|
|
}
|