gpg: parse_packets() should get file-like stream

and wrap it with util.Reader()

trezor_agent/gpg/decode.py

@@ -218,9 +218,10 @@ def parse_packets(stream):
 
     See https://tools.ietf.org/html/rfc4880#section-4.2 for details.
     """
+    reader = util.Reader(stream)
     while True:
         try:
-            value = stream.readfmt('B')
+            value = reader.readfmt('B')
         except EOFError:
             return
 
@@ -232,20 +233,20 @@ def parse_packets(stream):
             length_type = util.low_bits(tag, 2)
             tag = tag >> 2
             fmt = {0: '>B', 1: '>H', 2: '>L'}[length_type]
-            packet_size = stream.readfmt(fmt)
+            packet_size = reader.readfmt(fmt)
         else:
-            first = stream.readfmt('B')
+            first = reader.readfmt('B')
             if first < 192:
                 packet_size = first
             elif first < 224:
-                packet_size = ((first - 192) << 8) + stream.readfmt('B') + 192
+                packet_size = ((first - 192) << 8) + reader.readfmt('B') + 192
             elif first == 255:
-                packet_size = stream.readfmt('>L')
+                packet_size = reader.readfmt('>L')
             else:
                 log.error('Partial Body Lengths unsupported')
 
         log.debug('packet length: %d', packet_size)
-        packet_data = stream.read(packet_size)
+        packet_data = reader.read(packet_size)
         packet_type = PACKET_TYPES.get(tag)
 
         if packet_type is not None:
@@ -281,7 +282,7 @@ HASH_ALGORITHMS = {
 def load_public_key(pubkey_bytes, use_custom=False, ecdh=False):
     """Parse and validate GPG public key from an input stream."""
     stream = io.BytesIO(pubkey_bytes)
-    packets = list(parse_packets(util.Reader(stream)))
+    packets = list(parse_packets(stream))
     pubkey, userid, signature = packets[:3]
     packets = packets[3:]
 
@@ -318,7 +319,7 @@ def load_public_key(pubkey_bytes, use_custom=False, ecdh=False):
 
 def load_signature(stream, original_data):
     """Load signature from stream, and compute GPG digest for verification."""
-    signature, = list(parse_packets(util.Reader(stream)))
+    signature, = list(parse_packets((stream)))
     hash_alg = HASH_ALGORITHMS[signature['hash_alg']]
     digest = digest_packets([{'_to_hash': original_data}, signature],
                             hasher=hashlib.new(hash_alg))

trezor_agent/gpg/tests/test_decode.py

@@ -40,7 +40,7 @@ zpR9luXTKwMEl+mlZmwEFKZXBmir
 =oyj0
 -----END PGP PUBLIC KEY BLOCK-----
 '''
-    stream = util.Reader(io.BytesIO(decode.remove_armor(data)))
+    stream = io.BytesIO(decode.remove_armor(data))
     pubkey, user_id, signature = list(decode.parse_packets(stream))
     expected_pubkey = {
         'created': 1464355030, 'type': 'pubkey', 'tag': 6,