tests: Add test of the LUA dissector

This just adds the test. It is not enabled yet in CI.

Author: mefistotelis

tests/test_comm_dissector.py

@@ -0,0 +1,88 @@
+# -*- coding: utf-8 -*-
+
+""" Test for dji-firmware-tools, comm_dissector scripts.
+
+    This test verifies functions of the script by using
+    `tshark`, command line Wireshark utility.
+"""
+
+# Copyright (C) 2023 Mefistotelis <mefistotelis@gmail.com>
+# Copyright (C) 2023 Original Gangsters <https://dji-rev.slack.com/>
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+pckt_mavic_air_fcc = [0x55, 0x17, 0x04, 0x38, 0x02, 0x0e, 0x1d, 0x00, 0x40, 0x07, 0x30, 0x55, 0x53, 0x00, 0x00, 0x55, 0x53, 0x00, 0x00, 0x01, 0x00, 0xfe, 0x5d]
+pckt_mini_2_fcc = [0x55, 0x18, 0x04, 0x20, 0x02, 0x09, 0x00, 0x00, 0x40, 0x09, 0x27, 0x00, 0x02, 0x48, 0x00, 0xff, 0xff, 0x02, 0x00, 0x00, 0x00, 0x00, 0x81, 0x1f]
+
+import logging
+import subprocess
+import os
+import re
+import sys
+import struct
+import time
+import datetime
+import pytest
+
+import array
+
+LOGGER = logging.getLogger(__name__)
+
+def write_one_packet_pcap(fname, userdlt, data):
+    with open(fname, "wb") as out:
+        out.write(struct.pack("=IHHiIII",
+            0xa1b2c3d4,   # magic number
+            2,            # major version number
+            4,            # minor version number
+            0,            # GMT to local correction
+            0,            # accuracy of timestamps
+            65535,        # max length of captured packets, in octets
+            147+userdlt, # data link type (DLT) - USER_0
+        ))
+
+        dtime = datetime.datetime.now()
+        timestamp = int(time.mktime(dtime.timetuple()))
+        out.write(struct.pack("=IIII",
+            timestamp,        # timestamp seconds
+            dtime.microsecond, # timestamp microseconds
+            len(data),        # number of octets of packet saved in file
+            len(data),        # actual length of packet
+        ))
+        out.write(data)
+
+def run_comm_dissector_tshark_show(cmd, inp_file, proto_name, pkt_cmd, env=None):
+    command = [cmd, '-r', inp_file, '-V']
+    LOGGER.info(' '.join(command))
+    prc_result = subprocess.run(command, env=env, capture_output=True)
+    assert prc_result.returncode == 0
+    # Check if protocol name is found in tshark output (protocol was recognized)
+    assert str(prc_result.stdout).find(proto_name) > 0
+    # Check if command from the packet is found in tshark output (packet header was dissected)
+    match = re.search(r'\s+Cmd: [A-Za-z0-9 \//,.-]+ [\(]0x([0-9a-f]+)[\)]', str(prc_result.stdout), re.IGNORECASE)
+    assert match
+    assert int(match.group(1), 16) == pkt_cmd
+
+def case_comm_dissector_tshark_show(pcap_file, userdlt, proto_name, pckt, env=None):
+    pkt_cmd = int(pckt[10])
+    write_one_packet_pcap(pcap_file, userdlt, bytearray(pckt))
+    run_comm_dissector_tshark_show("tshark", str(pcap_file), proto_name, pkt_cmd, env=env)
+
+# Make this a separate mark rather than comm, until our CI can execute this correctly
+@pytest.mark.commDISS
+def test_comm_dissector_tshark_show(tmp_path):
+    """ Test dissecting a packet with Wiresharks tshark.
+    """
+    test_env = os.environ.copy()
+    case_comm_dissector_tshark_show(tmp_path / "dji-packet.pcap", 3, "DJI_DUMLv1", pckt_mavic_air_fcc, env=test_env)
+    case_comm_dissector_tshark_show(tmp_path / "dji-packet.pcap", 3, "DJI_DUMLv1", pckt_mini_2_fcc, env=test_env)