utilities/ovs-pcap.in

   1 #! /usr/bin/env @PYTHON@
   2 #
   3 # Copyright (c) 2010 Nicira, Inc.
   4 #
   5 # Licensed under the Apache License, Version 2.0 (the "License");
   6 # you may not use this file except in compliance with the License.
   7 # You may obtain a copy of the License at:
   8 #
   9 #     http://www.apache.org/licenses/LICENSE-2.0
  10 #
  11 # Unless required by applicable law or agreed to in writing, software
  12 # distributed under the License is distributed on an "AS IS" BASIS,
  13 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  14 # See the License for the specific language governing permissions and
  15 # limitations under the License.
  16
  17 from __future__ import print_function
  18
  19 import binascii
  20 import getopt
  21 import struct
  22 import sys
  23
  24
  25 class PcapException(Exception):
  26     pass
  27
  28
  29 class PcapReader(object):
  30     def __init__(self, file_name):
  31         self.file = open(file_name, "rb")
  32         header = self.file.read(24)
  33         if len(header) != 24:
  34             raise PcapException("end of file reading pcap header")
  35         magic, version, thiszone, sigfigs, snaplen, network = \
  36             struct.unpack(">6I", header)
  37         if magic == 0xa1b2c3d4:
  38             self.header_format = ">4I"
  39         elif magic == 0xd4c3b2a1:
  40             self.header_format = "<4I"
  41         else:
  42             raise PcapException("bad magic %u reading pcap file "
  43                         "(expected 0xa1b2c3d4 or 0xd4c3b2a1)" % magic)
  44
  45     def read(self):
  46         header = self.file.read(16)
  47         if len(header) == 0:
  48             return None
  49         elif len(header) != 16:
  50             raise PcapException("end of file within pcap record header")
  51
  52         ts_sec, ts_usec, incl_len, orig_len = struct.unpack(self.header_format,
  53                                                             header)
  54         packet = self.file.read(incl_len)
  55         if len(packet) != incl_len:
  56             raise PcapException("end of file reading pcap packet data")
  57         return packet
  58
  59
  60 argv0 = sys.argv[0]
  61
  62
  63 def usage():
  64     print("""\
  65 %(argv0)s: print pcap file packet data as hex
  66 usage: %(argv0)s FILE
  67 where FILE is a PCAP file.
  68
  69 The following options are also available:
  70   -h, --help                  display this help message
  71   -V, --version               display version information\
  72 """ % {'argv0': argv0})
  73     sys.exit(0)
  74
  75
  76 if __name__ == "__main__":
  77     try:
  78         try:
  79             options, args = getopt.gnu_getopt(sys.argv[1:], 'hV',
  80                                               ['help', 'version'])
  81         except getopt.GetoptException as geo:
  82             sys.stderr.write("%s: %s\n" % (argv0, geo.msg))
  83             sys.exit(1)
  84
  85         for key, value in options:
  86             if key in ['-h', '--help']:
  87                 usage()
  88             elif key in ['-V', '--version']:
  89                 print("ovs-pcap (Open vSwitch) @VERSION@")
  90             else:
  91                 sys.exit(0)
  92
  93         if len(args) != 1:
  94             sys.stderr.write("%s: exactly 1 non-option argument required "
  95                              "(use --help for help)\n" % argv0)
  96             sys.exit(1)
  97
  98         reader = PcapReader(args[0])
  99         while True:
 100             packet = reader.read()
 101             if packet is None:
 102                 break
 103
 104             print(binascii.hexlify(packet).decode().strip())
 105
 106     except PcapException as e:
 107         sys.stderr.write("%s: %s\n" % (argv0, e))
 108         sys.exit(1)
 109
 110 # Local variables:
 111 # mode: python
 112 # End: