/
stun.py
219 lines (166 loc) · 6.55 KB
/
stun.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
# coding: utf-8
import random
import socket
import binascii
import struct
import argparse
STUN_PORT = 3478
FAMILY_IPv4 = '\x01'
FAMILY_IPv6 = '\x02'
# 0b00: Request
# 0b01: Binding
BINDING_REQUEST_SIGN = '\x00\x01' # 16bit (2bytes)
BINDING_RESPONSE_ERROR = '\x01\x11'
BINDING_RESPONSE_SUCCESS = '\x01\x01'
MAGIC_COOKIE = '\x21\x12\xA4\x42' # 固定値 32bit (4bytes)
# STUN Attribute Registry
MAPPED_ADDRESS = '\x00\x01'
RESPONSE_ADDRESS = '\x00\x02'
CHANGE_REQUEST = '\x00\x03'
SOURCE_ADDRESS = '\x00\x04'
CHANGED_ADDRESS = '\x00\x05'
USERNAME = '\x00\x06'
PASSWORD = '\x00\x07'
MESSAGE_INTEGRITY = '\x00\x08'
ERROR_CODE = '\x00\x09'
UNKNOWN_ATTRIBUTES = '\x00\x0A'
REFLECTED_FROM = '\x00\x0B'
REALM = '\x00\x14'
NONCE = '\x00\x15'
XOR_MAPPED_ADDRESS = '\x80\x82'
STUN_ATTRIBUTE_NAMES = {
MAPPED_ADDRESS: 'MAPPED-ADDRESS',
RESPONSE_ADDRESS: 'RESPONSE-ADDRESS',
CHANGE_REQUEST: 'CHANGE-REQUEST',
SOURCE_ADDRESS: 'SOURCE-ADDRESS',
CHANGED_ADDRESS: 'CHANGED-ADDRESS',
USERNAME: 'USERNAME',
PASSWORD: 'PASSWORD',
MESSAGE_INTEGRITY: 'MESSAGE-INTEGRITY',
ERROR_CODE: 'ERROR-CODE',
UNKNOWN_ATTRIBUTES: 'UNKNOWN-ATTRIBUTES',
REFLECTED_FROM: 'REFLECTED-FROM',
REALM: 'REALM',
NONCE: 'NONCE',
XOR_MAPPED_ADDRESS: 'XOR-MAPPED-ADDRESS',
'\x00\x20': 'XOR-MAPPED-ADDRESS',
}
socket.setdefaulttimeout(10)
def generate_transaction_id():
tid = []
for i in xrange(24): # 96bits (12bytes)
tid.append(random.choice('0123456789ABCDEF'))
return binascii.a2b_hex(''.join(tid))
def build_binding_request(transaction_id):
if len(transaction_id) != 12:
raise RuntimeError('Invalid transaction id')
body_length = '\x00\x00' # 属性無しなので0。 16bit (2bytes)
return ''.join([BINDING_REQUEST_SIGN, body_length, MAGIC_COOKIE, transaction_id])
def validate_response(buf, transaction_id):
if not buf or len(buf) < 20:
raise RuntimeError('Response too shoot')
response_sign = buf[:2]
if response_sign != BINDING_RESPONSE_SUCCESS:
if response_sign == BINDING_RESPONSE_ERROR:
raise RuntimeError('BINDING_RESPONSE_ERROR')
raise RuntimeError('Invalid Response')
response_magic_cookie = buf[4:8]
if MAGIC_COOKIE != response_magic_cookie:
raise RuntimeError('Invalid magic cookie')
response_transaction_id = buf[8:20]
if transaction_id != response_transaction_id:
raise RuntimeError('invalid transaction id')
def ip_to_bytes(ip, xor):
octets = [binascii.a2b_hex('%02x' % int(o)) for o in ip.split('.')]
addr_int = struct.unpack('!I', ''.join(octets))[0]
if xor:
magicCookieBytesInt = int(binascii.b2a_hex(MAGIC_COOKIE), 16)
addr_int = magicCookieBytesInt ^ addr_int
addr_bytes = binascii.a2b_hex('%08x' % addr_int)
return addr_bytes
def port_to_bytes(port, xor):
if xor:
magicCookieHighBytesInt = int(binascii.b2a_hex(MAGIC_COOKIE[:2]), 16)
port = magicCookieHighBytesInt ^ port
port_bytes = binascii.a2b_hex('%04x' % port)
return port_bytes
def read_mapped_address(attr_type, attr_body, attr_len):
assert attr_type in (MAPPED_ADDRESS, XOR_MAPPED_ADDRESS, '\x00\x20')
assert attr_body[:1] == '\x00' # 最初の 8bit (1bytes) は 0 に設定しなければならない
family_bytes = attr_body[1:2]
port_bytes = attr_body[2:4]
addr_bytes = attr_body[4:attr_len]
xor = attr_type in (XOR_MAPPED_ADDRESS, '\x00\x20')
family_text = ''
assert family_bytes in (FAMILY_IPv4, FAMILY_IPv6)
if family_bytes == FAMILY_IPv4:
family_text = 'IPv4'
elif family_bytes == FAMILY_IPv6:
family_text = 'IPv6'
# TODO: IPv6 に対応
port = int(binascii.b2a_hex(port_bytes), 16)
addr_int = int(binascii.b2a_hex(addr_bytes), 16)
if xor:
# port
magicCookieHighBytesInt = int(binascii.b2a_hex(MAGIC_COOKIE[:2]), 16)
port = magicCookieHighBytesInt ^ port
# addr
magicCookieBytesInt = int(binascii.b2a_hex(MAGIC_COOKIE), 16)
addr_int = magicCookieBytesInt ^ addr_int
octets = struct.pack('!I', addr_int)
ip = '.'.join([str(ord(c)) for c in octets])
return dict(name=STUN_ATTRIBUTE_NAMES[attr_type], ip=ip, port=port, family=family_text)
def read_attributes(attributes, body_length):
pos = 0
parsed_attributes = []
while pos < body_length:
attr_type = attributes[pos:pos + 2] # 16bit (2bytes)
attr_len = int(binascii.b2a_hex(attributes[pos + 2:pos + 4]), 16) # 16bit (2bytes)
attr_body = attributes[pos + 4:pos + 4 + attr_len]
if attr_type in (MAPPED_ADDRESS, XOR_MAPPED_ADDRESS, '\x00\x20'):
parsed_attributes.append(read_mapped_address(attr_type, attr_body, attr_len))
else:
parsed_attributes.append(dict(
name=STUN_ATTRIBUTE_NAMES.get(attr_type),
attr_type=attr_type,
attr_body=attr_body,
attr_len=attr_len
))
attr_head = (2 + 2) # attr_type + attr_len
remain = attr_len % 4
# 32bit 境界 (4bytes区切り) でない場合、詰め物有り
padding = 4 - remain if remain else 0
pos += attr_head + attr_len + padding
return parsed_attributes
class StunClient(object):
def __init__(self):
self.sock = None
self.transaction_id = None
self.req = None
def send_request(self, host, port=STUN_PORT):
self.transaction_id = generate_transaction_id()
self.req = build_binding_request(self.transaction_id)
self.sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
self.sock.bind(('0.0.0.0', 0))
self.sock.sendto(self.req, (host, port))
def receive_response(self):
buf, addr = self.sock.recvfrom(2048)
validate_response(buf, self.transaction_id)
body_length = int(binascii.b2a_hex(buf[2:4]), 16)
attributes = buf[20:]
# body_length と実際の attribules の長さは一致するはず
assert len(attributes) == body_length
return read_attributes(attributes, body_length)
def close(self):
if self.sock:
self.sock.close()
if __name__ == '__main__':
parser = argparse.ArgumentParser()
parser.add_argument('host', type=str, help='Stun server host name')
parser.add_argument('--port', type=int, help='Stun server port', nargs='?', default=STUN_PORT)
args = parser.parse_args()
client = StunClient()
client.send_request(args.host, args.port)
print client.receive_response()
client.close()