projects / oddments / cappie.git / blame
| Commit | Line | Data |
|---|---|---|
| 53478050 MT |
1 | #!/usr/bin/python |
| 2 | ############################################################################### | |
| 3 | # # | |
| 4 | # Cappie # | |
| 5 | # Copyright (C) 2010 Michael Tremer # | |
| 6 | # # | |
| 7 | # This program is free software: you can redistribute it and/or modify # | |
| 8 | # it under the terms of the GNU General Public License as published by # | |
| 9 | # the Free Software Foundation, either version 3 of the License, or # | |
| 10 | # (at your option) any later version. # | |
| 11 | # # | |
| 12 | # This program is distributed in the hope that it will be useful, # | |
| 13 | # but WITHOUT ANY WARRANTY; without even the implied warranty of # | |
| 14 | # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # | |
| 15 | # GNU General Public License for more details. # | |
| 16 | # # | |
| 17 | # You should have received a copy of the GNU General Public License # | |
| 18 | # along with this program. If not, see <http://www.gnu.org/licenses/>. # | |
| 19 | # # | |
| 20 | ############################################################################### | |
| 21 | ||
| 22 | import struct | |
| 23 | ||
| 24 | from constants import * | |
| 25 | from errors import * | |
| 26 | ||
| 27 | def val2int(val): | |
| 28 | return int("".join(["%02d" % ord(c) for c in val]), 16) | |
| 29 | ||
| 30 | def val2ip4(val): | |
| 31 | return ".".join(["%d" % ord(i) for i in val]) | |
| 32 | ||
| 33 | def val2mac(val): | |
| 34 | return ":".join(["%02x" % ord(i) for i in val]) | |
| 35 | ||
| 36 | def decode_packet(data): | |
| 37 | for func in (decode_arp_packet,): | |
| 38 | try: | |
| 39 | p = func(data) | |
| 40 | except PacketTypeError: | |
| 41 | continue | |
| 42 | ||
| 43 | return p | |
| 44 | ||
| 45 | raise PacketTypeError, "Could not determine type of packet" | |
| 46 | ||
| 47 | def decode_arp_packet(data): | |
| 48 | operationmap = { | |
| 49 | 1 : OPERATION_REQUEST, | |
| 50 | 2 : OPERATION_RESPONSE, | |
| 51 | } | |
| 52 | ||
| 53 | #if not len(data) == 42: | |
| 54 | # raise DecodeError, "Data has wrong length: %d" % len(data) | |
| 55 | ||
| 56 | ret = { | |
| 57 | "type" : TYPE_ARP, | |
| 58 | } | |
| 59 | ||
| 60 | #"hwtype" : data[:2], | |
| 61 | protocol = val2int(struct.unpack("!2s", data[12:14])[0]) | |
| 62 | hw_addr_size = val2int(struct.unpack("!1s", data[18:19])[0]) | |
| 63 | hw_prot_size = val2int(struct.unpack("!1s", data[19:20])[0]) | |
| 64 | operation = val2int(struct.unpack("!2s", data[20:22])[0]) | |
| 65 | ||
| 66 | # Sanity checks | |
| 67 | if not protocol == 0x0806: | |
| 68 | raise PacketTypeError, "Not an ARP packet" | |
| 69 | ||
| 70 | # TODO Must check hwtype here... | |
| 71 | ||
| 72 | try: | |
| 73 | ret["operation"] = operationmap[operation] | |
| 74 | except KeyError: | |
| 75 | raise DecodeError, "Unknown operation type" | |
| 76 | ||
| 77 | address_length = hw_addr_size + hw_prot_size | |
| 78 | unpack_str = "!%ss%ss" % (hw_addr_size, hw_prot_size) | |
| 79 | ||
| 80 | ret["source_address"], ret["source_ip_address"] = \ | |
| 81 | struct.unpack(unpack_str, data[22:22 + address_length]) | |
| 82 | ||
| 83 | ret["destination_address"], ret["destination_ip_address"] = \ | |
| 84 | struct.unpack(unpack_str, data[22 + address_length:22 + address_length * 2]) | |
| 85 | ||
| 86 | for i in ("source_address", "destination_address"): | |
| 87 | ret[i] = val2mac(ret[i]) | |
| 88 | ||
| 89 | for i in ("source_ip_address", "destination_ip_address"): | |
| 90 | ret[i] = val2ip4(ret[i]) | |
| 91 | ||
| 92 | return ret | |
| 93 | ||
| 94 | def decode_ndp_packet(data): | |
| 95 | raise PacketTypeError |