mirror of
https://github.com/emanuele-f/PCAPdroid.git
synced 2026-05-08 21:12:26 +00:00
emanuele-f
e00870b23e
- snaplen: limit the size of a every packet - max_pkts_per_flow - max_dump_size: stop the capture when the size limit is reached
122 lines
3.8 KiB
Python
Executable File
122 lines
3.8 KiB
Python
Executable File
#!/usr/bin/env python3
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#
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# This file is part of PCAPdroid.
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#
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# PCAPdroid is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# PCAPdroid is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with PCAPdroid. If not, see <http://www.gnu.org/licenses/>.
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#
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# Copyright 2020-21 - Emanuele Faranda
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#
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import socket
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import sys
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import argparse
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# The buffer to hold the received UDP data
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BUFSIZE = 65535
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PCAP_HEADER_SIZE = 24
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# Standard PCAP header (struct pcap_hdr_s). Must be sent before any other PCAP record (struct pcaprec_hdr_s).
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# magic: 0xa1b2c3d4, v2.4
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PCAP_HDR_BYTES_PREFIX = bytes.fromhex("d4c3b2a1020004000000000000000000")
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# snaplen: 65535, LINKTYPE_RAW
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PCAP_HDR_BYTES_RAW_SUFFIX = bytes.fromhex("ffff000065000000")
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# snaplen: 65535, LINKTYPE_ETHERNET
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PCAP_HDR_BYTES_ETHER_SUFFIX = bytes.fromhex("ffff000001000000")
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# PCAP header when PCAPDroid trailer is in use
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# magic: 0xa1b2c3d4, v2.4
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PCAPDROID_TRAILER_MAGIC = bytes.fromhex("01072021")
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PCAPDROID_TRAILER_SIZE = 32
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example = '''example:
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udp_receiver.py -p 1234 | wireshark -k -i -
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'''
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parser = argparse.ArgumentParser(
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description='''Receives data from the PCAPdroid app and outputs it to stdout.''',
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epilog=example,
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formatter_class=argparse.RawDescriptionHelpFormatter)
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parser.add_argument('-p', '--port', type=int, help='The UDP port to listen', default=1234)
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parser.add_argument('-v', '--verbose', help='Enable verbose log to stderr', action='store_true')
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parser.add_argument('-w', '--write', help='Write the PCAP to the specified file', metavar='FILE', default="-")
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args = parser.parse_args()
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outf = None
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if args.write != '-':
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outf = open(args.write, "wb")
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def write(data):
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if outf:
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outf.write(data)
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else:
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sys.stdout.buffer.write(data)
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sys.stdout.flush()
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def main_loop():
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sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
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sock.bind(("0.0.0.0", args.port))
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pcap_header_sent = False
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# Send the individual records (struct pcaprec_hdr_s)
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while True:
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data, addr = sock.recvfrom(BUFSIZE)
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is_pcap_header = (len(data) == PCAP_HEADER_SIZE) and (data.startswith(PCAP_HDR_BYTES_PREFIX))
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if(args.verbose):
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sys.stderr.write("Got a {}B packet\n".format(len(data)))
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if(not pcap_header_sent) and (not is_pcap_header):
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# This tool was started after PCAPdroid, so we must build a PCAP header
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# Determine is the PCAPDroid trailer is in use
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offset = len(data) - PCAPDROID_TRAILER_SIZE
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has_trailer = ((offset > 0) and (data[offset:offset+4] == PCAPDROID_TRAILER_MAGIC))
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if(args.verbose):
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sys.stderr.write("Sending PCAP header (trailer " + ("not " if not has_trailer else "") + "detected)\n")
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# Send the PCAP header before any other data
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suffix = PCAP_HDR_BYTES_RAW_SUFFIX if not has_trailer else PCAP_HDR_BYTES_ETHER_SUFFIX
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write(PCAP_HDR_BYTES_PREFIX + suffix)
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pcap_header_sent = True
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elif is_pcap_header:
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if pcap_header_sent:
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# PCAPdroid has been restarted, ignore the PCAP header
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if(args.verbose):
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sys.stderr.write("PCAP header detected, skipping\n");
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continue
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else:
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if(args.verbose):
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sys.stderr.write("PCAP header detected\n");
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pcap_header_sent = True
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# this is a PCAP header/record, send it
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write(data)
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if __name__ == "__main__":
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try:
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main_loop()
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except KeyboardInterrupt:
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sys.stderr.write("Terminating...")
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if outf:
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outf.close()
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exit(0)
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