# $Id: stun.py 47 2008-05-27 02:10:00Z jon.oberheide $
# -*- coding: utf-8 -*-
"""Simple Traversal of UDP through NAT."""
from __future__ import print_function
from __future__ import absolute_import
import struct
from . import dpkt
# STUN - RFC 3489
# http://tools.ietf.org/html/rfc3489
# Each packet has a 20 byte header followed by 0 or more attribute TLVs.
# Message Types
BINDING_REQUEST = 0x0001
BINDING_RESPONSE = 0x0101
BINDING_ERROR_RESPONSE = 0x0111
SHARED_SECRET_REQUEST = 0x0002
SHARED_SECRET_RESPONSE = 0x0102
SHARED_SECRET_ERROR_RESPONSE = 0x0112
# Message Attributes
MAPPED_ADDRESS = 0x0001
RESPONSE_ADDRESS = 0x0002
CHANGE_REQUEST = 0x0003
SOURCE_ADDRESS = 0x0004
CHANGED_ADDRESS = 0x0005
USERNAME = 0x0006
PASSWORD = 0x0007
MESSAGE_INTEGRITY = 0x0008
ERROR_CODE = 0x0009
UNKNOWN_ATTRIBUTES = 0x000a
REFLECTED_FROM = 0x000b
[docs]class STUN(dpkt.Packet):
"""Simple Traversal of UDP through NAT.
STUN - RFC 3489
http://tools.ietf.org/html/rfc3489
Each packet has a 20 byte header followed by 0 or more attribute TLVs.
Attributes:
__hdr__: Header fields of STUN.
TODO.
"""
__hdr__ = (
('type', 'H', 0),
('len', 'H', 0),
('xid', '16s', 0)
)
[docs]def tlv(buf):
n = 4
t, l = struct.unpack('>HH', buf[:n])
v = buf[n:n + l]
pad = (n - l % n) % n
buf = buf[n + l + pad:]
return t, l, v, buf
[docs]def parse_attrs(buf):
"""Parse STUN.data buffer into a list of (attribute, data) tuples."""
attrs = []
while buf:
t, _, v, buf = tlv(buf)
attrs.append((t, v))
return attrs
[docs]def test_stun_response():
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'
m = STUN(s)
assert m.type == BINDING_RESPONSE
assert m.len == 12
attrs = parse_attrs(m.data)
assert attrs == [(MAPPED_ADDRESS, b'\x00\x01\x11\x22\x33\x44\x55\x66'), ]
[docs]def test_stun_padded():
s = (b'\x00\x01\x00\x54\x21\x12\xa4\x42\x35\x59\x53\x6e\x42\x71\x70\x56\x77\x61\x39\x4f\x00\x06'
b'\x00\x17\x70\x4c\x79\x5a\x48\x52\x3a\x47\x77\x4c\x33\x41\x48\x42\x6f\x76\x75\x62\x4c\x76'
b'\x43\x71\x6e\x00\x80\x2a\x00\x08\x18\x8b\x10\x4c\x69\x7b\xf6\x5b\x00\x25\x00\x00\x00\x24'
b'\x00\x04\x6e\x00\x1e\xff\x00\x08\x00\x14\x60\x2b\xc7\xfc\x0d\x10\x63\xaa\xc5\x38\x1c\xcb'
b'\x96\xa9\x73\x08\x73\x9a\x96\x0c\x80\x28\x00\x04\xd1\x62\xea\x65')
m = STUN(s)
assert m.type == BINDING_REQUEST
assert m.len == 84
attrs = parse_attrs(m.data)
assert len(attrs) == 6
assert attrs[0] == (USERNAME, b'pLyZHR:GwL3AHBovubLvCqn')
assert attrs[4][0] == MESSAGE_INTEGRITY
if __name__ == '__main__':
test_stun_response()
test_stun_padded()
print('Tests Successful...')