func CheckC2(s1, c2 []byte) (uint32, error) {
server_pos := rtmp.ValidateDigest(s1, 8, rtmp.GENUINE_FMS_KEY[:36])
if server_pos == 0 {
server_pos = rtmp.ValidateDigest(s1, 772, rtmp.GENUINE_FMS_KEY[:36])
if server_pos == 0 {
return 0, errors.New("Server response validating failed")
}
}
digest, err := rtmp.HMACsha256(s1[server_pos:server_pos+rtmp.SHA256_DIGEST_LENGTH], rtmp.GENUINE_FP_KEY)
rtmp.CheckError(err, "Get digest from s1 error")
signature, err := rtmp.HMACsha256(c2[:rtmp.RTMP_SIG_SIZE-rtmp.SHA256_DIGEST_LENGTH], digest)
rtmp.CheckError(err, "Get signature from c2 error")
if bytes.Compare(signature, c2[rtmp.RTMP_SIG_SIZE-rtmp.SHA256_DIGEST_LENGTH:]) != 0 {
return 0, errors.New("Server signature mismatch")
}
return server_pos, nil
}
func main() {
flag.Usage = func() {
fmt.Fprintf(os.Stderr, "%s version[%s]\r\nUsage: %s [OPTIONS]\r\n", programName, version, os.Args[0])
flag.PrintDefaults()
}
flag.Parse()
// listen
listen, err := net.Listen("tcp", ":1935")
if err != nil {
log.Println("Listen error", err)
os.Exit(-1)
}
defer listen.Close()
for {
iconn, err := listen.Accept()
if err != nil {
log.Println("Accept error", err)
os.Exit(-1)
}
if iconn == nil {
log.Println("iconn is nil")
os.Exit(-1)
}
defer iconn.Close()
// Handshake
// C>>>P: C0+C1
ibr := bufio.NewReader(iconn)
ibw := bufio.NewWriter(iconn)
c0, err := ibr.ReadByte()
if c0 != 0x03 {
log.Printf("C>>>P: C0(0x%2x) != 0x03\n", c0)
os.Exit(-1)
}
c1 := make([]byte, rtmp.RTMP_SIG_SIZE)
_, err = io.ReadAtLeast(ibr, c1, rtmp.RTMP_SIG_SIZE)
// Check C1
var clientDigestOffset uint32
if clientDigestOffset, err = CheckC1(c1, true); err != nil {
log.Println("C>>>P: Test C1 err:", err)
os.Exit(-1)
}
// P>>>S: Connect Server
oconn, err := net.Dial("tcp", "192.168.20.111:1935")
if err != nil {
log.Println("P>>>S: Dial server err:", err)
os.Exit(-1)
}
defer oconn.Close()
obr := bufio.NewReader(oconn)
obw := bufio.NewWriter(oconn)
// P>>>S: C0+C1
if err = obw.WriteByte(c0); err != nil {
log.Println("P>>>S: Write C0 err:", err)
os.Exit(-1)
}
if _, err = obw.Write(c1); err != nil {
log.Println("P>>>S: Write C1 err:", err)
os.Exit(-1)
}
if err = obw.Flush(); err != nil {
log.Println("P>>>S: Flush err:", err)
os.Exit(-1)
}
// P<<<S: Read S0+S1+S2
s0, err := obr.ReadByte()
if err != nil {
log.Println("P<<<S: Read S0 err:", err)
os.Exit(-1)
}
if c0 != 0x03 {
log.Printf("P<<<S: S0(0x%2x) != 0x03\n", s0)
os.Exit(-1)
}
s1 := make([]byte, rtmp.RTMP_SIG_SIZE)
_, err = io.ReadAtLeast(obr, s1, rtmp.RTMP_SIG_SIZE)
if err != nil {
log.Println("P<<<S: Read S1 err:", err)
os.Exit(-1)
}
s2 := make([]byte, rtmp.RTMP_SIG_SIZE)
_, err = io.ReadAtLeast(obr, s2, rtmp.RTMP_SIG_SIZE)
if err != nil {
log.Println("P<<<S: Read S2 err:", err)
os.Exit(-1)
}
// C<<<P: Send S0+S1+S2
if err = ibw.WriteByte(s0); err != nil {
log.Println("C<<<P: Write S0 err:", err)
os.Exit(-1)
}
if _, err = ibw.Write(s1); err != nil {
log.Println("C<<<P: Write S1 err:", err)
os.Exit(-1)
}
if _, err = ibw.Write(s2); err != nil {
log.Println("C<<<P: Write S2 err:", err)
os.Exit(-1)
}
if err = ibw.Flush(); err != nil {
log.Println("C<<<P: Flush err:", err)
os.Exit(-1)
}
// C>>>P: Read C2
c2 := make([]byte, rtmp.RTMP_SIG_SIZE)
_, err = io.ReadAtLeast(ibr, c2, rtmp.RTMP_SIG_SIZE)
// Check S2
server_pos := rtmp.ValidateDigest(s1, 8, rtmp.GENUINE_FP_KEY[:30])
if server_pos == 0 {
server_pos = rtmp.ValidateDigest(s1, 772, rtmp.GENUINE_FP_KEY[:30])
if server_pos == 0 {
log.Println("P<<<S: S1 position check error")
os.Exit(-1)
}
}
digest, err := rtmp.HMACsha256(c1[clientDigestOffset:clientDigestOffset+rtmp.SHA256_DIGEST_LENGTH], rtmp.GENUINE_FMS_KEY)
rtmp.CheckError(err, "Get digest from c1 error")
signature, err := rtmp.HMACsha256(s2[:rtmp.RTMP_SIG_SIZE-rtmp.SHA256_DIGEST_LENGTH], digest)
rtmp.CheckError(err, "Get signature from s2 error")
if bytes.Compare(signature, s2[rtmp.RTMP_SIG_SIZE-rtmp.SHA256_DIGEST_LENGTH:]) != 0 {
log.Println("Server signature mismatch")
os.Exit(-1)
}
digestResp, err := rtmp.HMACsha256(s1[server_pos:server_pos+rtmp.SHA256_DIGEST_LENGTH], rtmp.GENUINE_FP_KEY)
rtmp.CheckError(err, "Generate C2 HMACsha256 digestResp")
signatureResp, err := rtmp.HMACsha256(c2[:rtmp.RTMP_SIG_SIZE-rtmp.SHA256_DIGEST_LENGTH], digestResp)
if bytes.Compare(signatureResp, c2[rtmp.RTMP_SIG_SIZE-rtmp.SHA256_DIGEST_LENGTH:]) != 0 {
log.Println("C2 mismatch")
os.Exit(-1)
}
// P>>>S: Send C2
if _, err = obw.Write(c2); err != nil {
log.Println("P>>>S: Write C2 err:", err)
os.Exit(-1)
}
if err = obw.Flush(); err != nil {
log.Println("P>>>S: Flush err:", err)
os.Exit(-1)
}
// Proxy
go io.Copy(iconn, oconn)
go io.Copy(oconn, iconn)
}
}