forked from bluenviron/mediamtx
/
handshake.go
298 lines (221 loc) · 4.47 KB
/
handshake.go
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// Package handshake contains the RTMP handshake mechanism.
package handshake
import (
"bytes"
"fmt"
"io"
)
const (
encryptedVersion = 3<<24 | 5<<16 | 1<<8 | 1
)
func doClientEncrypted(rw io.ReadWriter) ([]byte, []byte, error) {
var c0 C0S0
c0.Version = 6
err := c0.Write(rw)
if err != nil {
return nil, nil, err
}
localPrivateKey, localPublicKey, err := dhGenerateKeyPair()
if err != nil {
return nil, nil, err
}
var c1 C1S1
c1Digest, err := c1.fill(false, localPublicKey)
if err != nil {
return nil, nil, err
}
err = c1.Write(rw)
if err != nil {
return nil, nil, err
}
var s0 C0S0
err = s0.Read(rw)
if err != nil {
return nil, nil, err
}
if s0.Version != 6 {
return nil, nil, fmt.Errorf("server replied with unexpected version %d", s0.Version)
}
var s1 C1S1
err = s1.Read(rw)
if err != nil {
return nil, nil, err
}
s1Digest, remotePublicKey, err := s1.validate(true)
if err != nil {
return nil, nil, err
}
var s2 C2S2
err = s2.Read(rw)
if err != nil {
return nil, nil, err
}
err = s2.validate(true, c1Digest)
if err != nil {
return nil, nil, err
}
var c2 C2S2
err = c2.fill(false, s1Digest)
if err != nil {
return nil, nil, err
}
err = c2.Write(rw)
if err != nil {
return nil, nil, err
}
sharedSecret := dhComputeSharedSecret(localPrivateKey, remotePublicKey)
keyIn := hmacSha256(sharedSecret, localPublicKey)[:16]
keyOut := hmacSha256(sharedSecret, remotePublicKey)[:16]
return keyIn, keyOut, nil
}
func doClientPlain(rw io.ReadWriter, strict bool) error {
var c0 C0S0
c0.Version = 3
err := c0.Write(rw)
if err != nil {
return err
}
var c1 C1S1
err = c1.fillPlain()
if err != nil {
return err
}
err = c1.Write(rw)
if err != nil {
return err
}
var s0 C0S0
err = s0.Read(rw)
if err != nil {
return err
}
if s0.Version != 3 {
return fmt.Errorf("server replied with unexpected version %d", s0.Version)
}
var s1 C1S1
err = s1.Read(rw)
if err != nil {
return err
}
var s2 C2S2
err = s2.Read(rw)
if err != nil {
return err
}
if strict && !bytes.Equal(s2.Data, c1.Data) {
return fmt.Errorf("data in S2 does not correspond")
}
var c2 C2S2
c2.Data = s1.Data
return c2.Write(rw)
}
// DoClient performs a client-side handshake.
func DoClient(rw io.ReadWriter, encrypted bool, strict bool) ([]byte, []byte, error) {
if encrypted {
return doClientEncrypted(rw)
}
return nil, nil, doClientPlain(rw, strict)
}
func doServerEncrypted(rw io.ReadWriter) ([]byte, []byte, error) {
var c1 C1S1
err := c1.Read(rw)
if err != nil {
return nil, nil, err
}
c1Digest, remotePublicKey, err := c1.validate(false)
if err != nil {
return nil, nil, err
}
localPrivateKey, localPublicKey, err := dhGenerateKeyPair()
if err != nil {
return nil, nil, err
}
var s0 C0S0
s0.Version = 6
err = s0.Write(rw)
if err != nil {
return nil, nil, err
}
var s1 C1S1
s1.Version = encryptedVersion
s1Digest, err := s1.fill(true, localPublicKey)
if err != nil {
return nil, nil, err
}
err = s1.Write(rw)
if err != nil {
return nil, nil, err
}
var s2 C2S2
s2.Time2 = encryptedVersion
err = s2.fill(true, c1Digest)
if err != nil {
return nil, nil, err
}
err = s2.Write(rw)
if err != nil {
return nil, nil, err
}
var c2 C2S2
err = c2.Read(rw)
if err != nil {
return nil, nil, err
}
err = c2.validate(false, s1Digest)
if err != nil {
return nil, nil, err
}
sharedSecret := dhComputeSharedSecret(localPrivateKey, remotePublicKey)
keyIn := hmacSha256(sharedSecret, localPublicKey)[:16]
keyOut := hmacSha256(sharedSecret, remotePublicKey)[:16]
return keyIn, keyOut, nil
}
func doServerPlain(rw io.ReadWriter, strict bool) error {
var c1 C1S1
err := c1.Read(rw)
if err != nil {
return err
}
var s0 C0S0
s0.Version = 3
err = s0.Write(rw)
if err != nil {
return err
}
var s1 C1S1
err = s1.fillPlain()
if err != nil {
return err
}
err = s1.Write(rw)
if err != nil {
return err
}
var s2 C2S2
s2.Data = c1.Data
err = s2.Write(rw)
if err != nil {
return err
}
var c2 C2S2
err = c2.Read(rw)
if err != nil {
return err
}
if strict && !bytes.Equal(c2.Data, s1.Data) {
return fmt.Errorf("data in C2 does not correspond")
}
return nil
}
// DoServer performs a server-side handshake.
func DoServer(rw io.ReadWriter, strict bool) ([]byte, []byte, error) {
var c0 C0S0
err := c0.Read(rw)
if err != nil {
return nil, nil, err
}
if c0.Version == 6 {
return doServerEncrypted(rw)
}
return nil, nil, doServerPlain(rw, strict)
}