TREZOR v1 protocol codec

src/trezor/wire/wire_codec_v1.py

@@ -0,0 +1,82 @@
+import ustruct
+
+SESSION_V1 = const(0)
+REP_MARKER_V1 = const(63) # ord('?)
+REP_MARKER_V1_LEN = const(1) # len('?')
+
+_MSG_HEADER_MAGIC = const(35) # org('#')
+_MSG_HEADER_V1 = '>BBHL'  # wire type, data length
+_MSG_HEADER_V1_LEN = ustruct.calcsize(_MSG_HEADER_V1)
+
+def detect_v1(data):
+    return (data[0] == REP_MARKER_V1)
+
+def parse_report_v1(data):
+    return None, SESSION_V1, data[1:]
+
+def parse_message(data):
+    magic1, magic2, msg_type, data_len = ustruct.unpack(_MSG_HEADER_V1, data)
+    if magic1 != _MSG_HEADER_MAGIC or magic2 != _MSG_HEADER_MAGIC:
+        raise Exception("Corrupted magic bytes")
+
+    return msg_type, data_len, data[_MSG_HEADER_V1_LEN:]
+
+def serialize_message_header(data, msg_type, msg_len):
+    ustruct.pack_into(_MSG_HEADER_V1, data, REP_MARKER_V1_LEN, _MSG_HEADER_MAGIC, _MSG_HEADER_MAGIC, msg_type, msg_len)
+
+def decode_wire_v1_stream(genfunc, session_id, *args):
+    '''Decode a v1 wire message from the report data and stream it to target.
+
+Receives report payloads.
+Sends (msg_type, data_len) to target, followed by data chunks.
+Throws EOFError after last data chunk, in case of valid checksum.
+Throws MessageChecksumError to target if data doesn't match the checksum.
+'''
+    
+    message = yield # read first report
+    msg_type, data_len, data = parse_message(message)
+
+    print(msg_type, data_len, bytes(data))
+    target = genfunc(msg_type, data_len, session_id, *args)
+    target.send(None)
+
+    while data_len > 0:
+
+        data_chunk = data[:data_len]  # slice off the garbage at the end
+        data = data[len(data_chunk):]  # slice off what we have read
+        data_len -= len(data_chunk)
+        target.send(data_chunk)
+
+        if data_len > 0:
+            data = yield # First next record
+
+    target.throw(EOFError())
+
+def encode_wire_v1_message(msg_type, msg_data, target):
+    report = memoryview(bytearray(64)) # Maximum report length
+    report[0] = REP_MARKER_V1 # Put report marker
+    serialize_message_header(report, msg_type, len(msg_data))
+
+    source_data = memoryview(msg_data)
+    target_data = report[REP_MARKER_V1_LEN+_MSG_HEADER_V1_LEN:]
+
+    while True:
+        # move as much as possible from source to target
+        n = min(len(target_data), len(source_data))
+        target_data[:n] = source_data[:n]
+        source_data = source_data[n:]
+        target_data = target_data[n:]
+
+        # FIXME: Optimize speed
+        x = 0
+        to_fill = len(target_data)
+        while x < to_fill:
+            target_data[x] = 0
+            x += 1
+
+        target.send(report)
+
+        if not source_data:
+            break
+
+        target_data = report[REP_MARKER_V1_LEN:]