feat(gateway): validate encrypted Apollo RTSP frames

gateway/apollo_rtsp_test.go

@@ -0,0 +1,56 @@
+package gateway
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"encoding/binary"
+	"testing"
+)
+
+func TestEncryptedRTSPRejectsTagReplayAndReorderedHostFrames(t *testing.T) {
+	key := []byte("0123456789abcdef")
+	codec, err := newEncryptedRTSPCodec(key)
+	if err != nil {
+		t.Fatal(err)
+	}
+	first := hostEncryptedRTSPFrame(t, key, 1, []byte("RTSP/1.0 200 OK\r\n\r\n"))
+	if plaintext, err := codec.OpenHost(first); err != nil || string(plaintext) != "RTSP/1.0 200 OK\r\n\r\n" {
+		t.Fatalf("OpenHost() = %q, %v", plaintext, err)
+	}
+	if _, err := codec.OpenHost(first); err == nil {
+		t.Fatal("OpenHost() accepted a replayed frame")
+	}
+	tampered := hostEncryptedRTSPFrame(t, key, 2, []byte("RTSP/1.0 200 OK\r\n\r\n"))
+	tampered[len(tampered)-1] ^= 0x01
+	if _, err := codec.OpenHost(tampered); err == nil {
+		t.Fatal("OpenHost() accepted a tag failure")
+	}
+	third := hostEncryptedRTSPFrame(t, key, 3, []byte("RTSP/1.0 200 OK\r\n\r\n"))
+	if _, err := codec.OpenHost(third); err != nil {
+		t.Fatalf("OpenHost() sequence 3 error = %v", err)
+	}
+	second := hostEncryptedRTSPFrame(t, key, 2, []byte("RTSP/1.0 200 OK\r\n\r\n"))
+	if _, err := codec.OpenHost(second); err == nil {
+		t.Fatal("OpenHost() accepted an out-of-order frame")
+	}
+}
+
+func hostEncryptedRTSPFrame(t *testing.T, key []byte, sequence uint32, plaintext []byte) []byte {
+	t.Helper()
+	block, err := aes.NewCipher(key)
+	if err != nil {
+		t.Fatal(err)
+	}
+	aead, err := cipher.NewGCM(block)
+	if err != nil {
+		t.Fatal(err)
+	}
+	nonce := encryptedRTSPNonce(sequence, 'H', 'R')
+	sealed := aead.Seal(nil, nonce[:], plaintext, nil)
+	frame := make([]byte, encryptedRTSPHeaderSize+len(plaintext))
+	binary.BigEndian.PutUint32(frame[:4], uint32(len(plaintext))|0x80000000)
+	binary.BigEndian.PutUint32(frame[4:8], sequence)
+	copy(frame[8:24], sealed[len(plaintext):])
+	copy(frame[24:], sealed[:len(plaintext)])
+	return frame
+}