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-rwxr-xr-xsrc/target/fake_trx/trx_sniff.py318
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diff --git a/src/target/fake_trx/trx_sniff.py b/src/target/fake_trx/trx_sniff.py
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+#!/usr/bin/env python2
+# -*- coding: utf-8 -*-
+
+# Scapy-based TRX interface sniffer
+#
+# (C) 2018 by Vadim Yanitskiy <axilirator@gmail.com>
+#
+# All Rights Reserved
+#
+# 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 2 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, write to the Free Software Foundation, Inc.,
+# 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+
+import signal
+import getopt
+import sys
+
+import scapy.all
+
+COPYRIGHT = \
+ "Copyright (C) 2018 by Vadim Yanitskiy <axilirator@gmail.com>\n" \
+ "License GPLv2+: GNU GPL version 2 or later " \
+ "<http://gnu.org/licenses/gpl.html>\n" \
+ "This is free software: you are free to change and redistribute it.\n" \
+ "There is NO WARRANTY, to the extent permitted by law.\n"
+
+class Application:
+ # Application variables
+ sniff_interface = "lo"
+ sniff_base_port = 5700
+ print_bursts = False
+ output_file = None
+
+ # Counters
+ cnt_burst_dropped_num = 0
+ cnt_burst_break = None
+ cnt_burst_num = 0
+
+ cnt_frame_break = None
+ cnt_frame_last = None
+ cnt_frame_num = 0
+
+ # Burst direction fliter
+ bf_dir_l12trx = None
+
+ # Timeslot number filter
+ bf_tn_val = None
+
+ # Frame number fliter
+ bf_fn_lt = None
+ bf_fn_gt = None
+
+ # Internal variables
+ lo_trigger = False
+
+ def __init__(self):
+ print(COPYRIGHT)
+ self.parse_argv()
+
+ # Open requested file for writing
+ if self.output_file is not None:
+ self.output_file = open(self.output_file, "ab")
+
+ def run(self):
+ # Compose a packet filter
+ pkt_filter = "udp and (port %d or port %d)" \
+ % (self.sniff_base_port + 2, self.sniff_base_port + 102)
+
+ print("[i] Listening on interface '%s'..." % self.sniff_interface)
+
+ # Start sniffing...
+ scapy.all.sniff(iface = self.sniff_interface, store = 1,
+ filter = pkt_filter, prn = self.pkt_handler)
+
+ # Scapy registers its own signal handler
+ self.shutdown()
+
+ def pkt_handler(self, ether):
+ # Prevent loopback packet duplication
+ if self.sniff_interface == "lo":
+ self.lo_trigger = not self.lo_trigger
+ if not self.lo_trigger:
+ return
+
+ # Extract a TRX payload
+ ip = ether.payload
+ udp = ip.payload
+ trx = udp.payload
+
+ # Convert to bytearray
+ trx = bytearray(str(trx))
+
+ # Parse GSM TDMA specific data
+ fn = (trx[1] << 24) | (trx[2] << 16) | (trx[3] << 8) | trx[4]
+ tn = trx[0]
+
+ # Determine a burst direction (L1 <-> TRX)
+ l12trx = udp.sport > udp.dport
+
+ # Poke burst pass filter
+ rc = self.burst_pass_filter(l12trx, fn, tn)
+ if rc is False:
+ self.cnt_burst_dropped_num += 1
+ return
+
+ # Debug print
+ print("[i] %s burst: fn=%u, tn=%d" \
+ % ("L1 -> TRX" if l12trx else "TRX -> L1", fn, tn))
+
+ # Poke burst handler
+ rc = self.burst_handle(trx, l12trx, fn, tn)
+ if rc is False:
+ self.shutdown()
+
+ # Poke burst counter
+ rc = self.burst_count(fn, tn)
+ if rc is True:
+ self.shutdown()
+
+ def burst_pass_filter(self, l12trx, fn, tn):
+ # Direction filter
+ if self.bf_dir_l12trx is not None:
+ if l12trx != self.bf_dir_l12trx:
+ return False
+
+ # Timeslot filter
+ if self.bf_tn_val is not None:
+ if tn != self.bf_tn_val:
+ return False
+
+ # Frame number filter
+ if self.bf_fn_lt is not None:
+ if fn > self.bf_fn_lt:
+ return False
+ if self.bf_fn_gt is not None:
+ if fn < self.bf_fn_gt:
+ return False
+
+ # Burst passed ;)
+ return True
+
+ def burst_handle(self, trx_burst, l12trx, fn, tn):
+ if self.print_bursts:
+ self.burst_dump_bits(sys.stdout, trx_burst, l12trx)
+ sys.stdout.flush()
+
+ if self.output_file is not None:
+ # TLV: tag defines burst direction (one byte, BE)
+ self.output_file.write('\x01' if l12trx else '\x02')
+
+ # TLV: length of value (one byte, BE)
+ length = len(trx_burst)
+ self.output_file.write(chr(length))
+
+ # TLV: raw value
+ self.output_file.write(trx_burst)
+
+ return True
+
+ def burst_dump_bits(self, dst, trx_burst, l12trx):
+ # Split out burst header
+ if l12trx:
+ burst = trx_burst[6:]
+ else:
+ burst = trx_burst[8:]
+
+ # Print normal bits: 0 or 1
+ for i in range(0, 148):
+ # Convert bits to chars
+ if l12trx:
+ # Convert bits as is
+ bit = '1' if burst[i] else '0'
+ else:
+ # Convert trx bits {254..0} to sbits {-127..127}
+ bit = -127 if burst[i] == 255 else 127 - burst[i]
+ # Convert sbits {-127..127} to ubits {0..1}
+ bit = '1' if bit < 0 else '0'
+
+ # Write a normal bit
+ dst.write(bit)
+ dst.write("\n")
+
+ def burst_count(self, fn, tn):
+ # Update frame counter
+ if self.cnt_frame_last is None:
+ self.cnt_frame_last = fn
+ self.cnt_frame_num += 1
+ else:
+ if fn != self.cnt_frame_last:
+ self.cnt_frame_num += 1
+
+ # Update burst counter
+ self.cnt_burst_num += 1
+
+ # Stop sniffing after N bursts
+ if self.cnt_burst_break is not None:
+ if self.cnt_burst_num == self.cnt_burst_break:
+ print("[i] Collected required amount of bursts")
+ return True
+
+ # Stop sniffing after N frames
+ if self.cnt_frame_break is not None:
+ if self.cnt_frame_num == self.cnt_frame_break:
+ print("[i] Collected required amount of frames")
+ return True
+
+ return False
+
+ def shutdown(self):
+ print("[i] Shutting down...")
+
+ # Print statistics
+ print("[i] %u bursts handled, %u dropped" \
+ % (self.cnt_burst_num, self.cnt_burst_dropped_num))
+
+ # Close output file if opened
+ if self.output_file is not None:
+ self.output_file.close()
+
+ # Exit
+ sys.exit(0)
+
+ def print_help(self, msg = None):
+ s = " Usage: " + sys.argv[0] + " [options]\n\n" \
+ " Some help...\n" \
+ " -h --help this text\n\n"
+
+ s += " Sniffing options\n" \
+ " -i --sniff-interface Set network interface (default '%s')\n" \
+ " -p --sniff-base-port Set base port number (default %d)\n\n"
+
+ s += " Processing (no processing by default)\n" \
+ " -o --output-file Write bursts to file\n" \
+ " -v --print-bits Print burst bits to stdout\n\n" \
+
+ s += " Count limitations (disabled by default)\n" \
+ " --frame-count NUM Stop after sniffing NUM frames\n" \
+ " --burst-count NUM Stop after sniffing NUM bursts\n\n"
+
+ s += " Filtering (disabled by default)\n" \
+ " --direction DIR Burst direction: L12TRX or TRX2L1\n" \
+ " --timeslot NUM TDMA timeslot number [0..7]\n" \
+ " --frame-num-lt NUM TDMA frame number lower than NUM\n" \
+ " --burst-num-gt NUM TDMA frame number greater than NUM\n"
+
+ print(s % (self.sniff_interface, self.sniff_base_port))
+
+ if msg is not None:
+ print(msg)
+
+ def parse_argv(self):
+ try:
+ opts, args = getopt.getopt(sys.argv[1:],
+ "i:p:o:v:h", ["help", "sniff-interface=", "sniff-base-port=",
+ "frame-count=", "burst-count=", "direction=",
+ "timeslot=", "frame-num-lt=", "frame-num-gt=",
+ "output-file=", "print-bits"])
+ except getopt.GetoptError as err:
+ self.print_help("[!] " + str(err))
+ sys.exit(2)
+
+ for o, v in opts:
+ if o in ("-h", "--help"):
+ self.print_help()
+ sys.exit(2)
+
+ elif o in ("-i", "--sniff-interface"):
+ self.sniff_interface = v
+ elif o in ("-p", "--sniff-base-port"):
+ self.sniff_base_port = int(v)
+
+ elif o in ("-o", "--output-file"):
+ self.output_file = v
+ elif o in ("-v", "--print-bits"):
+ self.print_bursts = True
+
+ # Break counters
+ elif o == "--frame-count":
+ self.cnt_frame_break = int(v)
+ elif o == "--burst-count":
+ self.cnt_burst_break = int(v)
+
+ # Direction filter
+ elif o == "--direction":
+ if v == "L12TRX":
+ self.bf_dir_l12trx = True
+ elif v == "TRX2L1":
+ self.bf_dir_l12trx = False
+ else:
+ self.print_help("[!] Wrong direction argument")
+ sys.exit(2)
+
+ # Timeslot pass filter
+ elif o == "--timeslot":
+ self.bf_tn_val = int(v)
+ if self.bf_tn_val < 0 or self.bf_tn_val > 7:
+ self.print_help("[!] Wrong timeslot value")
+ sys.exit(2)
+
+ # Frame number pass filter
+ elif o == "--frame-num-lt":
+ self.bf_fn_lt = int(v)
+ elif o == "--frame-num-gt":
+ self.bf_fn_gt = int(v)
+
+if __name__ == '__main__':
+ app = Application()
+ app.run()
generated by cgit v1.2.3 (git 2.25.1) at 2024-05-19 16:11:33 +0000