Package dpkt :: Module stun
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Source Code for Module dpkt.stun

  1  # $Id: stun.py 47 2008-05-27 02:10:00Z jon.oberheide $ 
  2  # -*- coding: utf-8 -*- 
  3  """Simple Traversal of UDP through NAT.""" 
  4  from __future__ import print_function 
  5  from __future__ import absolute_import 
  6   
  7  import struct 
  8   
  9  from . import dpkt 
 10   
 11  # STUN - RFC 3489 
 12  # http://tools.ietf.org/html/rfc3489 
 13  # Each packet has a 20 byte header followed by 0 or more attribute TLVs. 
 14   
 15  # Message Types 
 16  BINDING_REQUEST = 0x0001 
 17  BINDING_RESPONSE = 0x0101 
 18  BINDING_ERROR_RESPONSE = 0x0111 
 19  SHARED_SECRET_REQUEST = 0x0002 
 20  SHARED_SECRET_RESPONSE = 0x0102 
 21  SHARED_SECRET_ERROR_RESPONSE = 0x0112 
 22   
 23  # Message Attributes 
 24  MAPPED_ADDRESS = 0x0001 
 25  RESPONSE_ADDRESS = 0x0002 
 26  CHANGE_REQUEST = 0x0003 
 27  SOURCE_ADDRESS = 0x0004 
 28  CHANGED_ADDRESS = 0x0005 
 29  USERNAME = 0x0006 
 30  PASSWORD = 0x0007 
 31  MESSAGE_INTEGRITY = 0x0008 
 32  ERROR_CODE = 0x0009 
 33  UNKNOWN_ATTRIBUTES = 0x000a 
 34  REFLECTED_FROM = 0x000b 
 35   
 36   
37 -class STUN(dpkt.Packet):
38 """Simple Traversal of UDP through NAT. 39 40 STUN - RFC 3489 41 http://tools.ietf.org/html/rfc3489 42 Each packet has a 20 byte header followed by 0 or more attribute TLVs. 43 44 Attributes: 45 __hdr__: Header fields of STUN. 46 TODO. 47 """ 48 49 __hdr__ = ( 50 ('type', 'H', 0), 51 ('len', 'H', 0), 52 ('xid', '16s', 0) 53 )
54 55
56 -def tlv(buf):
57 n = 4 58 t, l = struct.unpack('>HH', buf[:n]) 59 v = buf[n:n + l] 60 pad = (n - l % n) % n 61 buf = buf[n + l + pad:] 62 return t, l, v, buf
63 64
65 -def parse_attrs(buf):
66 """Parse STUN.data buffer into a list of (attribute, data) tuples.""" 67 attrs = [] 68 while buf: 69 t, _, v, buf = tlv(buf) 70 attrs.append((t, v)) 71 return attrs
72 73
74 -def test_stun_response():
75 s = b'\x01\x01\x00\x0c\x21\x12\xa4\x42\x53\x4f\x70\x43\x69\x69\x35\x4a\x66\x63\x31\x7a\x00\x01\x00\x08\x00\x01\x11\x22\x33\x44\x55\x66' 76 m = STUN(s) 77 assert m.type == BINDING_RESPONSE 78 assert m.len == 12 79 80 attrs = parse_attrs(m.data) 81 assert attrs == [(MAPPED_ADDRESS, b'\x00\x01\x11\x22\x33\x44\x55\x66'), ]
82 83
84 -def test_stun_padded():
85 s = (b'\x00\x01\x00\x54\x21\x12\xa4\x42\x35\x59\x53\x6e\x42\x71\x70\x56\x77\x61\x39\x4f\x00\x06' 86 b'\x00\x17\x70\x4c\x79\x5a\x48\x52\x3a\x47\x77\x4c\x33\x41\x48\x42\x6f\x76\x75\x62\x4c\x76' 87 b'\x43\x71\x6e\x00\x80\x2a\x00\x08\x18\x8b\x10\x4c\x69\x7b\xf6\x5b\x00\x25\x00\x00\x00\x24' 88 b'\x00\x04\x6e\x00\x1e\xff\x00\x08\x00\x14\x60\x2b\xc7\xfc\x0d\x10\x63\xaa\xc5\x38\x1c\xcb' 89 b'\x96\xa9\x73\x08\x73\x9a\x96\x0c\x80\x28\x00\x04\xd1\x62\xea\x65') 90 m = STUN(s) 91 assert m.type == BINDING_REQUEST 92 assert m.len == 84 93 94 attrs = parse_attrs(m.data) 95 assert len(attrs) == 6 96 assert attrs[0] == (USERNAME, b'pLyZHR:GwL3AHBovubLvCqn') 97 assert attrs[4][0] == MESSAGE_INTEGRITY
98 99 100 if __name__ == '__main__': 101 test_stun_response() 102 test_stun_padded() 103 104 print('Tests Successful...') 105