Add capture parser

This commit adds contrib/message-capture/message-capture-parser.py, a python
script to be used alongside -capturemessages to parse the captured
messages.

It is complete with arguments and will parse any file given, sorting the
messages in the files when creating the output.  If an output file is
specified with -o or --output, it will dump the messages in json format
to that file, otherwise it will print to stdout.

The small change to the unused msg_generic is to bring it in line with
the other message classes, purely to avoid a bug in the future.

contrib/message-capture/message-capture-parser.py

@@ -0,0 +1,214 @@
+#!/usr/bin/env python3
+# Copyright (c) 2020 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""Parse message capture binary files.  To be used in conjunction with -capturemessages."""
+
+import argparse
+import os
+import shutil
+import sys
+from io import BytesIO
+import json
+from pathlib import Path
+from typing import Any, List, Optional
+
+sys.path.append(os.path.join(os.path.dirname(__file__), '../../test/functional'))
+
+from test_framework.messages import ser_uint256     # noqa: E402
+from test_framework.p2p import MESSAGEMAP           # noqa: E402
+
+TIME_SIZE = 8
+LENGTH_SIZE = 4
+MSGTYPE_SIZE = 12
+
+# The test framework classes stores hashes as large ints in many cases.
+# These are variables of type uint256 in core.
+# There isn't a way to distinguish between a large int and a large int that is actually a blob of bytes.
+# As such, they are itemized here.
+# Any variables with these names that are of type int are actually uint256 variables.
+# (These can be easily found by looking for calls to deser_uint256, deser_uint256_vector, and uint256_from_str in messages.py)
+HASH_INTS = [
+    "blockhash",
+    "block_hash",
+    "hash",
+    "hashMerkleRoot",
+    "hashPrevBlock",
+    "hashstop",
+    "prev_header",
+    "sha256",
+    "stop_hash",
+]
+
+HASH_INT_VECTORS = [
+    "hashes",
+    "headers",
+    "vHave",
+    "vHash",
+]
+
+
+class ProgressBar:
+    def __init__(self, total: float):
+        self.total = total
+        self.running = 0
+
+    def set_progress(self, progress: float):
+        cols = shutil.get_terminal_size()[0]
+        if cols <= 12:
+            return
+        max_blocks = cols - 9
+        num_blocks = int(max_blocks * progress)
+        print('\r[ {}{} ] {:3.0f}%'
+              .format('#' * num_blocks,
+                      ' ' * (max_blocks - num_blocks),
+                      progress * 100),
+              end ='')
+
+    def update(self, more: float):
+        self.running += more
+        self.set_progress(self.running / self.total)
+
+
+def to_jsonable(obj: Any) -> Any:
+    if hasattr(obj, "__dict__"):
+        return obj.__dict__
+    elif hasattr(obj, "__slots__"):
+        ret = {}    # type: Any
+        for slot in obj.__slots__:
+            val = getattr(obj, slot, None)
+            if slot in HASH_INTS and isinstance(val, int):
+                ret[slot] = ser_uint256(val).hex()
+            elif slot in HASH_INT_VECTORS and isinstance(val[0], int):
+                ret[slot] = [ser_uint256(a).hex() for a in val]
+            else:
+                ret[slot] = to_jsonable(val)
+        return ret
+    elif isinstance(obj, list):
+        return [to_jsonable(a) for a in obj]
+    elif isinstance(obj, bytes):
+        return obj.hex()
+    else:
+        return obj
+
+
+def process_file(path: str, messages: List[Any], recv: bool, progress_bar: Optional[ProgressBar]) -> None:
+    with open(path, 'rb') as f_in:
+        if progress_bar:
+            bytes_read = 0
+
+        while True:
+            if progress_bar:
+                # Update progress bar
+                diff = f_in.tell() - bytes_read - 1
+                progress_bar.update(diff)
+                bytes_read = f_in.tell() - 1
+
+            # Read the Header
+            tmp_header_raw = f_in.read(TIME_SIZE + LENGTH_SIZE + MSGTYPE_SIZE)
+            if not tmp_header_raw:
+                break
+            tmp_header = BytesIO(tmp_header_raw)
+            time = int.from_bytes(tmp_header.read(TIME_SIZE), "little")      # type: int
+            msgtype = tmp_header.read(MSGTYPE_SIZE).split(b'\x00', 1)[0]     # type: bytes
+            length = int.from_bytes(tmp_header.read(LENGTH_SIZE), "little")  # type: int
+
+            # Start converting the message to a dictionary
+            msg_dict = {}
+            msg_dict["direction"] = "recv" if recv else "sent"
+            msg_dict["time"] = time
+            msg_dict["size"] = length   # "size" is less readable here, but more readable in the output
+
+            msg_ser = BytesIO(f_in.read(length))
+
+            # Determine message type
+            if msgtype not in MESSAGEMAP:
+                # Unrecognized message type
+                try:
+                    msgtype_tmp = msgtype.decode()
+                    if not msgtype_tmp.isprintable():
+                        raise UnicodeDecodeError
+                    msg_dict["msgtype"] = msgtype_tmp
+                except UnicodeDecodeError:
+                    msg_dict["msgtype"] = "UNREADABLE"
+                msg_dict["body"] = msg_ser.read().hex()
+                msg_dict["error"] = "Unrecognized message type."
+                messages.append(msg_dict)
+                print(f"WARNING - Unrecognized message type {msgtype} in {path}", file=sys.stderr)
+                continue
+
+            # Deserialize the message
+            msg = MESSAGEMAP[msgtype]()
+            msg_dict["msgtype"] = msgtype.decode()
+
+            try:
+                msg.deserialize(msg_ser)
+            except KeyboardInterrupt:
+                raise
+            except Exception:
+                # Unable to deserialize message body
+                msg_ser.seek(0, os.SEEK_SET)
+                msg_dict["body"] = msg_ser.read().hex()
+                msg_dict["error"] = "Unable to deserialize message."
+                messages.append(msg_dict)
+                print(f"WARNING - Unable to deserialize message in {path}", file=sys.stderr)
+                continue
+
+            # Convert body of message into a jsonable object
+            if length:
+                msg_dict["body"] = to_jsonable(msg)
+            messages.append(msg_dict)
+
+        if progress_bar:
+            # Update the progress bar to the end of the current file
+            # in case we exited the loop early
+            f_in.seek(0, os.SEEK_END)   # Go to end of file
+            diff = f_in.tell() - bytes_read - 1
+            progress_bar.update(diff)
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description=__doc__,
+        epilog="EXAMPLE \n\t{0} -o out.json <data-dir>/message_capture/**/*.dat".format(sys.argv[0]),
+        formatter_class=argparse.RawTextHelpFormatter)
+    parser.add_argument(
+        "capturepaths",
+        nargs='+',
+        help="binary message capture files to parse.")
+    parser.add_argument(
+        "-o", "--output",
+        help="output file.  If unset print to stdout")
+    parser.add_argument(
+        "-n", "--no-progress-bar",
+        action='store_true',
+        help="disable the progress bar.  Automatically set if the output is not a terminal")
+    args = parser.parse_args()
+    capturepaths = [Path.cwd() / Path(capturepath) for capturepath in args.capturepaths]
+    output = Path.cwd() / Path(args.output) if args.output else False
+    use_progress_bar = (not args.no_progress_bar) and sys.stdout.isatty()
+
+    messages = []   # type: List[Any]
+    if use_progress_bar:
+        total_size = sum(capture.stat().st_size for capture in capturepaths)
+        progress_bar = ProgressBar(total_size)
+    else:
+        progress_bar = None
+
+    for capture in capturepaths:
+        process_file(str(capture), messages, "recv" in capture.stem, progress_bar)
+
+    messages.sort(key=lambda msg: msg['time'])
+
+    if use_progress_bar:
+        progress_bar.set_progress(1)
+
+    jsonrep = json.dumps(messages)
+    if output:
+        with open(str(output), 'w+', encoding="utf8") as f_out:
+            f_out.write(jsonrep)
+    else:
+        print(jsonrep)
+
+if __name__ == "__main__":
+    main()

test/functional/test_framework/messages.py

@@ -1273,7 +1273,7 @@ def __repr__(self):
 # for cases where a user needs tighter control over what is sent over the wire
 # note that the user must supply the name of the msgtype, and the data
 class msg_generic:
-    __slots__ = ("msgtype", "data")
+    __slots__ = ("data")
 
     def __init__(self, msgtype, data=None):
         self.msgtype = msgtype