108 lines
3.2 KiB
Python
Executable File
108 lines
3.2 KiB
Python
Executable File
#!/usr/bin/env python3
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# Generate the array of Certificate Transparency Log ID to description mappings
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# for the TLS dissector.
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#
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# To update the TLS dissector source file, run this from the source directory:
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#
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# python3 tools/make-tls-ct-logids.py --update
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#
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import argparse
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from base64 import b64decode, b64encode
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import itertools
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import requests
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from hashlib import sha256
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# Begin of comment, followed by the actual array definition
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HEADER = "/* Generated by tools/make-tls-ct-logids.py\n"
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# See also https://www.certificate-transparency.org/known-logs
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CT_JSON_URL = 'https://www.gstatic.com/ct/log_list/v2/all_logs_list.json'
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# File to be patched
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SOURCE_FILE = "epan/dissectors/packet-tls-utils.c"
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# Maximum elements per line in the value array. 11 is chosen because it results
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# in output consistent with clang-format.
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BYTES_PER_LINE = 11
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def escape_c(s):
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return s.replace('\\', '\\\\').replace('"', '\\"')
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def byteshex(b):
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return " ".join("0x%02x," % b for b in bytearray(b))
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def process_json(obj, lastmod):
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logs = list(itertools.chain(*[op['logs'] for op in obj['operators']]))
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lines = HEADER
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lines += " * Last-Modified %s, %s entries. */\n" % (lastmod, len(logs))
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lines += "static const bytes_string ct_logids[] = {\n"
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for entry in logs:
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desc = entry["description"]
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pubkey_der = b64decode(entry["key"])
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key_id = sha256(pubkey_der).digest()
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lines += ' { (const guint8[]){\n'
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for offset in range(0, len(key_id), BYTES_PER_LINE):
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lines += ' %s\n' % \
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byteshex(key_id[offset:offset+BYTES_PER_LINE])
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lines += ' },\n'
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lines += ' %d, "%s" },\n' % (len(key_id), escape_c(desc))
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lines += " { NULL, 0, NULL }\n"
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lines += "};\n"
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return lines
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def parse_source():
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"""
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Reads the source file and tries to split it in the parts before, inside and
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after the block.
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"""
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begin, block, end = '', '', ''
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# Stages: 1 (before block), 2 (in block, skip), 3 (after block)
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stage = 1
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with open(SOURCE_FILE) as f:
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for line in f:
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if line == HEADER:
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stage = 2 # Begin of block
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if stage == 1:
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begin += line
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elif stage == 2:
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block += line
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if line.startswith('}'):
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stage = 3 # End of block reached
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elif stage == 3:
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end += line
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if stage != 3:
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raise RuntimeError("Could not parse file (in stage %d)" % stage)
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return begin, block, end
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parser = argparse.ArgumentParser()
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parser.add_argument("--update", action="store_true",
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help="Update %s as needed instead of writing to stdout" % SOURCE_FILE)
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def main():
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args = parser.parse_args()
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r = requests.get(CT_JSON_URL)
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code = process_json(r.json(), lastmod=r.headers['Last-Modified'])
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if args.update:
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begin, block, end = parse_source()
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if block == code:
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print("File is up-to-date")
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else:
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with open(SOURCE_FILE, "w") as f:
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f.write(begin)
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f.write(code)
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f.write(end)
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print("Updated %s" % SOURCE_FILE)
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else:
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print(code)
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if __name__ == '__main__':
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main()
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