refactor: Replace struct.pack/unpack.

basicswap/network.py

@@ -24,7 +24,6 @@ import queue
 import random
 import select
 import socket
-import struct
 import hashlib
 import logging
 import secrets
@@ -41,7 +40,7 @@ from basicswap.contrib.rfc6979 import (
 
 
 START_TOKEN = 0xabcd
-MSG_START_TOKEN = struct.pack('>H', START_TOKEN)
+MSG_START_TOKEN = START_TOKEN.to_bytes(2, 'big')
 
 MSG_MAX_SIZE = 0x200000  # 2MB
 
@@ -83,8 +82,8 @@ class MsgHandshake:
         pass
 
     def encode_aad(self):  # Additional Authenticated Data
-        return struct.pack('>H', NetMessageTypes.HANDSHAKE) + \
-            struct.pack('>Q', self._timestamp) + \
+        return int(NetMessageTypes.HANDSHAKE).to_bytes(2, 'big') + \
+            self._timestamp.to_bytes(8, 'big') + \
             self._ephem_pk
 
     def encode(self):
@@ -92,7 +91,7 @@ class MsgHandshake:
 
     def decode(self, msg_mv):
         o = 2
-        self._timestamp = struct.unpack('>Q', msg_mv[o: o + 8])[0]
+        self._timestamp = int.from_bytes(msg_mv[o: o + 8], 'big')
         o += 8
         self._ephem_pk = bytes(msg_mv[o: o + 33])
         o += 33
@@ -333,7 +332,7 @@ class Network:
 
             ss = k.ecdh(peer._pubkey)
 
-            hashed = hashlib.sha512(ss + struct.pack('>Q', msg._timestamp)).digest()
+            hashed = hashlib.sha512(ss + msg._timestamp.to_bytes(8, 'big')).digest()
             peer._ke = hashed[:32]
             peer._km = hashed[32:]
 
@@ -386,7 +385,7 @@ class Network:
             nk = PrivateKey(self._network_key)
             ss = nk.ecdh(msg._ephem_pk)
 
-            hashed = hashlib.sha512(ss + struct.pack('>Q', msg._timestamp)).digest()
+            hashed = hashlib.sha512(ss + msg._timestamp.to_bytes(8, 'big')).digest()
             peer._ke = hashed[:32]
             peer._km = hashed[32:]
 
@@ -427,7 +426,7 @@ class Network:
         mac = msg_mv[-16:]
         plaintext = cipher.decrypt_and_verify(msg_mv[2: -16], mac)
 
-        ping_nonce = struct.unpack('>I', plaintext[:4])[0]
+        ping_nonce = int.from_bytes(plaintext[:4], 'big')
         # Version is added to a ping following a handshake message
         if len(plaintext) >= 10:
             peer._ready = True
@@ -450,7 +449,7 @@ class Network:
         mac = msg_mv[-16:]
         plaintext = cipher.decrypt_and_verify(msg_mv[2: -16], mac)
 
-        pong_nonce = struct.unpack('>I', plaintext[:4])[0]
+        pong_nonce = int.from_bytes(plaintext[:4], 'big')
 
         if pong_nonce == peer._ping_nonce:
             peer._last_ping_rtt = (time.time_ns() // 1000) - peer._last_ping_at
@@ -462,14 +461,14 @@ class Network:
     def send_ping(self, peer):
         ping_nonce = random.getrandbits(32)
 
-        msg_bytes = struct.pack('>H', NetMessageTypes.PING)
+        msg_bytes = int(NetMessageTypes.PING).to_bytes(2, 'big')
         nonce = peer._sent_nonce[:24]
 
         cipher = ChaCha20_Poly1305.new(key=peer._ke, nonce=nonce)
         cipher.update(msg_bytes)
         cipher.update(nonce)
 
-        payload = struct.pack('>I', ping_nonce)
+        payload = ping_nonce.to_bytes(4, 'big')
         if peer._last_ping_at == 0:
             payload += self._sc._version
         ct, mac = cipher.encrypt_and_digest(payload)
@@ -484,14 +483,14 @@ class Network:
         self.send_msg(peer, msg_bytes)
 
     def send_pong(self, peer, ping_nonce):
-        msg_bytes = struct.pack('>H', NetMessageTypes.PONG)
+        msg_bytes = int(NetMessageTypes.PONG).to_bytes(2, 'big')
         nonce = peer._sent_nonce[:24]
 
         cipher = ChaCha20_Poly1305.new(key=peer._ke, nonce=nonce)
         cipher.update(msg_bytes)
         cipher.update(nonce)
 
-        payload = struct.pack('>I', ping_nonce)
+        payload = ping_nonce.to_bytes(4, 'big')
         ct, mac = cipher.encrypt_and_digest(payload)
         msg_bytes += ct + mac
 
@@ -503,7 +502,7 @@ class Network:
         msg_encoded = msg if isinstance(msg, bytes) else msg.encode()
         len_encoded = len(msg_encoded)
 
-        msg_packed = bytearray(MSG_START_TOKEN) + struct.pack('>I', len_encoded) + msg_encoded
+        msg_packed = bytearray(MSG_START_TOKEN) + len_encoded.to_bytes(4, 'big') + msg_encoded
         peer._socket.sendall(msg_packed)
 
         peer._bytes_sent += len_encoded
@@ -515,7 +514,7 @@ class Network:
         try:
             mv = memoryview(msg_bytes)
             o = 0
-            msg_type = struct.unpack('>H', mv[o: o + 2])[0]
+            msg_type = int.from_bytes(mv[o: o + 2], 'big')
             if msg_type == NetMessageTypes.HANDSHAKE:
                 self.process_handshake(peer, mv)
             elif msg_type == NetMessageTypes.PING:
@@ -548,13 +547,13 @@ class Network:
                         raise ValueError('Invalid start token')
                     o += 2
 
-                    msg_len = struct.unpack('>I', mv[o: o + 4])[0]
+                    msg_len = int.from_bytes(mv[o: o + 4], 'big')
                     o += 4
                     if msg_len < 2 or msg_len > MSG_MAX_SIZE:
                         raise ValueError('Invalid data length')
 
                     # Precheck msg_type
-                    msg_type = struct.unpack('>H', mv[o: o + 2])[0]
+                    msg_type = int.from_bytes(mv[o: o + 2], 'big')
                     # o += 2  # Don't inc offset, msg includes type
                     if not NetMessageTypes.has_value(msg_type):
                         raise ValueError('Invalid msg type')