Memory optimisation

internal/multiplex/crypto.go

@@ -45,9 +45,7 @@ func MakeAESGCMCipher(key []byte) (*AESGCM, error) {
 
 func (a *AESGCM) encrypt(plaintext []byte, nonce []byte) ([]byte, error) {
 	ciphertext := a.cipher.Seal(nil, nonce, plaintext, nil)
-	ret := make([]byte, len(plaintext)+16)
-	copy(ret, ciphertext)
-	return ret, nil
+	return ciphertext, nil
 }
 
 func (a *AESGCM) decrypt(ciphertext []byte, nonce []byte) ([]byte, error) {
@@ -75,9 +73,7 @@ func MakeCPCipher(key []byte) (*C20P1305, error) {
 
 func (c *C20P1305) encrypt(plaintext []byte, nonce []byte) ([]byte, error) {
 	ciphertext := c.cipher.Seal(nil, nonce, plaintext, nil)
-	ret := make([]byte, len(plaintext)+16)
-	copy(ret, ciphertext)
-	return ret, nil
+	return ciphertext, nil
 }
 
 func (c *C20P1305) decrypt(ciphertext []byte, nonce []byte) ([]byte, error) {

internal/multiplex/obfs.go

@@ -13,7 +13,7 @@ type Deobfser func([]byte) (*Frame, error)
 var u32 = binary.BigEndian.Uint32
 var putU32 = binary.BigEndian.PutUint32
 
-const headerLen = 12
+const HEADER_LEN = 12
 
 func genXorKey(key, salt []byte) []byte {
 	h := sha1.New()
@@ -29,17 +29,22 @@ func xor(a []byte, b []byte) {
 
 func MakeObfs(key []byte, algo Crypto) Obfser {
 	obfs := func(f *Frame) ([]byte, error) {
+		ret := make([]byte, 5+HEADER_LEN+len(f.Payload)+16)
+		recordLayer := ret[0:5]
+		header := ret[5 : 5+HEADER_LEN]
+		encryptedPayload := ret[5+HEADER_LEN:]
+
 		// header: [StreamID 4 bytes][Seq 4 bytes][Closing 1 byte][random 3 bytes]
-		header := make([]byte, headerLen)
 		putU32(header[0:4], f.StreamID)
 		putU32(header[4:8], f.Seq)
 		header[8] = f.Closing
 		rand.Read(header[9:12])
 
-		encryptedPayload, err := algo.encrypt(f.Payload, header)
+		ciphertext, err := algo.encrypt(f.Payload, header)
 		if err != nil {
 			return nil, err
 		}
+		copy(encryptedPayload, ciphertext)
 
 		cKey := make([]byte, len(key))
 		copy(cKey, key)
@@ -49,23 +54,18 @@ func MakeObfs(key []byte, algo Crypto) Obfser {
 
 		// Composing final obfsed message
 		// We don't use util.AddRecordLayer here to avoid unnecessary malloc
-		// TODO: allocate this in the beginning and do everything in place
-		obfsed := make([]byte, 5+headerLen+len(encryptedPayload))
-		obfsed[0] = 0x17
-		obfsed[1] = 0x03
-		obfsed[2] = 0x03
-		binary.BigEndian.PutUint16(obfsed[3:5], uint16(headerLen+len(encryptedPayload)))
-		copy(obfsed[5:5+headerLen], header)
-		copy(obfsed[5+headerLen:], encryptedPayload)
-		// obfsed: [record layer 5 bytes][obfsedheader 12 bytes][payload]
-		return obfsed, nil
+		recordLayer[0] = 0x17
+		recordLayer[1] = 0x03
+		recordLayer[2] = 0x03
+		binary.BigEndian.PutUint16(recordLayer[3:5], uint16(HEADER_LEN+len(encryptedPayload)))
+		return ret, nil
 	}
 	return obfs
 }
 
 func MakeDeobfs(key []byte, algo Crypto) Deobfser {
 	deobfs := func(in []byte) (*Frame, error) {
-		if len(in) < 5+headerLen+16 {
+		if len(in) < 5+HEADER_LEN+16 {
 			return nil, errors.New("Input cannot be shorter than 33 bytes")
 		}
 		peeled := in[5:]