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#!/usr/bin/env python
#
# Copyright 2015-2015 breakwa11
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations
# under the License.
from __future__ import absolute_import, division, print_function, \
with_statement
import os
import sys
import hashlib
import logging
import binascii
import base64
import time
import datetime
import random
import math
import struct
import zlib
import hmac
import hashlib
import shadowsocks
from shadowsocks import common, lru_cache, encrypt
from shadowsocks.obfsplugin import plain
from shadowsocks.common import to_bytes, to_str, ord, chr
def create_auth_chain_a(method):
return auth_chain_a(method)
obfs_map = {
'auth_chain_a': (create_auth_chain_a,),
}
class xorshift128plus(object):
max_int = (1 << 64) - 1
mov_mask = (1 << (64 - 23)) - 1
def __init__(self):
self.v0 = 0
self.v1 = 0
def next(self):
x = self.v0
y = self.v1
self.v0 = y
x ^= ((x & xorshift128plus.mov_mask) << 23)
x ^= (y ^ (x >> 17) ^ (y >> 26)) & xorshift128plus.max_int
self.v1 = x
return (x + y) & xorshift128plus.max_int
def init_from_bin(self, bin):
bin += b'\0' * 16
self.v0 = struct.unpack('<Q', bin[:8])[0]
self.v1 = struct.unpack('<Q', bin[8:16])[0]
def init_from_bin_len(self, bin, length):
bin += b'\0' * 16
bin = struct.pack('<H', length) + bin[2:]
self.v0 = struct.unpack('<Q', bin[:8])[0]
self.v1 = struct.unpack('<Q', bin[8:16])[0]
for i in range(4):
self.next()
def match_begin(str1, str2):
if len(str1) >= len(str2):
if str1[:len(str2)] == str2:
return True
return False
class auth_base(plain.plain):
def __init__(self, method):
super(auth_base, self).__init__(method)
self.method = method
self.no_compatible_method = ''
self.overhead = 4
def init_data(self):
return ''
def get_overhead(self, direction): # direction: true for c->s false for s->c
return self.overhead
def set_server_info(self, server_info):
self.server_info = server_info
def client_encode(self, buf):
return buf
def client_decode(self, buf):
return (buf, False)
def server_encode(self, buf):
return buf
def server_decode(self, buf):
return (buf, True, False)
def not_match_return(self, buf):
self.raw_trans = True
self.overhead = 0
if self.method == self.no_compatible_method:
return (b'E'*2048, False)
return (buf, False)
class client_queue(object):
def __init__(self, begin_id):
self.front = begin_id - 64
self.back = begin_id + 1
self.alloc = {}
self.enable = True
self.last_update = time.time()
self.ref = 0
def update(self):
self.last_update = time.time()
def addref(self):
self.ref += 1
def delref(self):
if self.ref > 0:
self.ref -= 1
def is_active(self):
return (self.ref > 0) and (time.time() - self.last_update < 60 * 10)
def re_enable(self, connection_id):
self.enable = True
self.front = connection_id - 64
self.back = connection_id + 1
self.alloc = {}
def insert(self, connection_id):
if not self.enable:
logging.warn('obfs auth: not enable')
return False
if not self.is_active():
self.re_enable(connection_id)
self.update()
if connection_id < self.front:
logging.warn('obfs auth: deprecated id, someone replay attack')
return False
if connection_id > self.front + 0x4000:
logging.warn('obfs auth: wrong id')
return False
if connection_id in self.alloc:
logging.warn('obfs auth: duplicate id, someone replay attack')
return False
if self.back <= connection_id:
self.back = connection_id + 1
self.alloc[connection_id] = 1
while (self.front in self.alloc) or self.front + 0x1000 < self.back:
if self.front in self.alloc:
del self.alloc[self.front]
self.front += 1
self.addref()
return True
class obfs_auth_chain_data(object):
def __init__(self, name):
self.name = name
self.user_id = {}
self.local_client_id = b''
self.connection_id = 0
self.set_max_client(64) # max active client count
def update(self, user_id, client_id, connection_id):
if user_id not in self.user_id:
self.user_id[user_id] = lru_cache.LRUCache()
local_client_id = self.user_id[user_id]
if client_id in local_client_id:
local_client_id[client_id].update()
def set_max_client(self, max_client):
self.max_client = max_client
self.max_buffer = max(self.max_client * 2, 1024)
def insert(self, user_id, client_id, connection_id):
if user_id not in self.user_id:
self.user_id[user_id] = lru_cache.LRUCache()
local_client_id = self.user_id[user_id]
if local_client_id.get(client_id, None) is None or not local_client_id[client_id].enable:
if local_client_id.first() is None or len(local_client_id) < self.max_client:
if client_id not in local_client_id:
#TODO: check
local_client_id[client_id] = client_queue(connection_id)
else:
local_client_id[client_id].re_enable(connection_id)
return local_client_id[client_id].insert(connection_id)
if not local_client_id[local_client_id.first()].is_active():
del local_client_id[local_client_id.first()]
if client_id not in local_client_id:
#TODO: check
local_client_id[client_id] = client_queue(connection_id)
else:
local_client_id[client_id].re_enable(connection_id)
return local_client_id[client_id].insert(connection_id)
logging.warn(self.name + ': no inactive client')
return False
else:
return local_client_id[client_id].insert(connection_id)
def remove(self, user_id, client_id):
if user_id in self.user_id:
local_client_id = self.user_id[user_id]
if client_id in local_client_id:
local_client_id[client_id].delref()
class auth_chain_a(auth_base):
def __init__(self, method):
super(auth_chain_a, self).__init__(method)
self.hashfunc = hashlib.md5
self.recv_buf = b''
self.unit_len = 2800
self.raw_trans = False
self.has_sent_header = False
self.has_recv_header = False
self.client_id = 0
self.connection_id = 0
self.max_time_dif = 60 * 60 * 24 # time dif (second) setting
self.salt = b"auth_chain_a"
self.no_compatible_method = 'auth_chain_a'
self.pack_id = 1
self.recv_id = 1
self.user_id = None
self.user_id_num = 0
self.user_key = None
self.overhead = 4
self.client_over_head = 4
self.last_client_hash = b''
self.last_server_hash = b''
self.random_client = xorshift128plus()
self.random_server = xorshift128plus()
self.encryptor = None
def init_data(self):
return obfs_auth_chain_data(self.method)
def get_overhead(self, direction): # direction: true for c->s false for s->c
return self.overhead
def set_server_info(self, server_info):
self.server_info = server_info
try:
max_client = int(server_info.protocol_param.split('#')[0])
except:
max_client = 64
self.server_info.data.set_max_client(max_client)
def trapezoid_random_float(self, d):
if d == 0:
return random.random()
s = random.random()
a = 1 - d
return (math.sqrt(a * a + 4 * d * s) - a) / (2 * d)
def trapezoid_random_int(self, max_val, d):
v = self.trapezoid_random_float(d)
return int(v * max_val)
def rnd_data_len(self, buf_size, last_hash, random):
if buf_size > 1440:
return 0
random.init_from_bin_len(last_hash, buf_size)
if buf_size > 1300:
return random.next() % 31
if buf_size > 900:
return random.next() % 127
if buf_size > 400:
return random.next() % 521
return random.next() % 1021
def udp_rnd_data_len(self, last_hash, random):
random.init_from_bin(last_hash)
return random.next() % 127
def rnd_start_pos(self, rand_len, random):
if rand_len > 0:
return random.next() % 8589934609 % rand_len
return 0
def rnd_data(self, buf_size, buf, last_hash, random):
rand_len = self.rnd_data_len(buf_size, last_hash, random)
rnd_data_buf = os.urandom(rand_len)
if buf_size == 0:
return rnd_data_buf
else:
if rand_len > 0:
start_pos = self.rnd_start_pos(rand_len, random)
return rnd_data_buf[:start_pos] + buf + rnd_data_buf[start_pos:]
else:
return buf
def pack_client_data(self, buf):
buf = self.encryptor.encrypt(buf)
data = self.rnd_data(len(buf), buf, self.last_client_hash, self.random_client)
data_len = len(data) + 8
mac_key = self.user_key + struct.pack('<I', self.pack_id)
length = len(buf) ^ struct.unpack('<H', self.last_client_hash[14:])[0]
data = struct.pack('<H', length) + data
self.last_client_hash = hmac.new(mac_key, data, self.hashfunc).digest()
data += self.last_client_hash[:2]
self.pack_id = (self.pack_id + 1) & 0xFFFFFFFF
return data
def pack_server_data(self, buf):
buf = self.encryptor.encrypt(buf)
data = self.rnd_data(len(buf), buf, self.last_server_hash, self.random_server)
data_len = len(data) + 8
mac_key = self.user_key + struct.pack('<I', self.pack_id)
length = len(buf) ^ struct.unpack('<H', self.last_server_hash[14:])[0]
data = struct.pack('<H', length) + data
self.last_server_hash = hmac.new(mac_key, data, self.hashfunc).digest()
data += self.last_server_hash[:2]
self.pack_id = (self.pack_id + 1) & 0xFFFFFFFF
return data
def pack_auth_data(self, auth_data, buf):
data = auth_data
data_len = 12 + 4 + 16 + 4
data = data + (struct.pack('<H', self.server_info.overhead) + struct.pack('<H', 0))
mac_key = self.server_info.iv + self.server_info.key
check_head = os.urandom(4)
self.last_client_hash = hmac.new(mac_key, check_head, self.hashfunc).digest()
check_head += self.last_client_hash[:8]
if b':' in to_bytes(self.server_info.protocol_param):
try:
items = to_bytes(self.server_info.protocol_param).split(b':')
self.user_key = items[1]
uid = struct.pack('<I', int(items[0]))
except:
uid = os.urandom(4)
else:
uid = os.urandom(4)
if self.user_key is None:
self.user_key = self.server_info.key
encryptor = encrypt.Encryptor(to_bytes(base64.b64encode(self.user_key)) + self.salt, 'aes-128-cbc', b'\x00' * 16)
uid = struct.unpack('<I', uid)[0] ^ struct.unpack('<I', self.last_client_hash[8:12])[0]
uid = struct.pack('<I', uid)
data = uid + encryptor.encrypt(data)[16:]
self.last_server_hash = hmac.new(self.user_key, data, self.hashfunc).digest()
data = check_head + data + self.last_server_hash[:4]
self.encryptor = encrypt.Encryptor(to_bytes(base64.b64encode(self.user_key)) + to_bytes(base64.b64encode(self.last_client_hash)), 'rc4')
return data + self.pack_client_data(buf)
def auth_data(self):
utc_time = int(time.time()) & 0xFFFFFFFF
if self.server_info.data.connection_id > 0xFF000000:
self.server_info.data.local_client_id = b''
if not self.server_info.data.local_client_id:
self.server_info.data.local_client_id = os.urandom(4)
logging.debug("local_client_id %s" % (binascii.hexlify(self.server_info.data.local_client_id),))
self.server_info.data.connection_id = struct.unpack('<I', os.urandom(4))[0] & 0xFFFFFF
self.server_info.data.connection_id += 1
return b''.join([struct.pack('<I', utc_time),
self.server_info.data.local_client_id,
struct.pack('<I', self.server_info.data.connection_id)])
def client_pre_encrypt(self, buf):
ret = b''
ogn_data_len = len(buf)
if not self.has_sent_header:
head_size = self.get_head_size(buf, 30)
datalen = min(len(buf), random.randint(0, 31) + head_size)
ret += self.pack_auth_data(self.auth_data(), buf[:datalen])
buf = buf[datalen:]
self.has_sent_header = True
while len(buf) > self.unit_len:
ret += self.pack_client_data(buf[:self.unit_len])
buf = buf[self.unit_len:]
ret += self.pack_client_data(buf)
return ret
def client_post_decrypt(self, buf):
if self.raw_trans:
return buf
self.recv_buf += buf
out_buf = b''
while len(self.recv_buf) > 4:
mac_key = self.user_key + struct.pack('<I', self.recv_id)
data_len = struct.unpack('<H', self.recv_buf[:2])[0] ^ struct.unpack('<H', self.last_server_hash[14:16])[0]
rand_len = self.rnd_data_len(data_len, self.last_server_hash, self.random_server)
length = data_len + rand_len
if length >= 4096:
self.raw_trans = True
self.recv_buf = b''
raise Exception('client_post_decrypt data error')
if length + 4 > len(self.recv_buf):
break
server_hash = hmac.new(mac_key, self.recv_buf[:length + 2], self.hashfunc).digest()
if server_hash[:2] != self.recv_buf[length + 2 : length + 4]:
logging.info('%s: checksum error, data %s' % (self.no_compatible_method, binascii.hexlify(self.recv_buf[:length])))
self.raw_trans = True
self.recv_buf = b''
raise Exception('client_post_decrypt data uncorrect checksum')
pos = 2
if data_len > 0 and rand_len > 0:
pos = 2 + self.rnd_start_pos(rand_len, self.random_server)
out_buf += self.encryptor.decrypt(self.recv_buf[pos : data_len + pos])
self.last_server_hash = server_hash
if self.recv_id == 1:
self.server_info.tcp_mss = struct.unpack('<H', out_buf[:2])[0]
out_buf = out_buf[2:]
self.recv_id = (self.recv_id + 1) & 0xFFFFFFFF
self.recv_buf = self.recv_buf[length + 4:]
return out_buf
def server_pre_encrypt(self, buf):
if self.raw_trans:
return buf
ret = b''
if self.pack_id == 1:
tcp_mss = self.server_info.tcp_mss if self.server_info.tcp_mss < 1500 else 1500
self.server_info.tcp_mss = tcp_mss
buf = struct.pack('<H', tcp_mss) + buf
self.unit_len = tcp_mss - self.client_over_head
while len(buf) > self.unit_len:
ret += self.pack_server_data(buf[:self.unit_len])
buf = buf[self.unit_len:]
ret += self.pack_server_data(buf)
return ret
def server_post_decrypt(self, buf):
if self.raw_trans:
return (buf, False)
self.recv_buf += buf
out_buf = b''
sendback = False
if not self.has_recv_header:
if len(self.recv_buf) >= 12 or len(self.recv_buf) in [7, 8]:
recv_len = min(len(self.recv_buf), 12)
mac_key = self.server_info.recv_iv + self.server_info.key
md5data = hmac.new(mac_key, self.recv_buf[:4], self.hashfunc).digest()
if md5data[:recv_len - 4] != self.recv_buf[4:recv_len]:
return self.not_match_return(self.recv_buf)
if len(self.recv_buf) < 12 + 24:
return (b'', False)
self.last_client_hash = md5data
uid = struct.unpack('<I', self.recv_buf[12:16])[0] ^ struct.unpack('<I', md5data[8:12])[0]
self.user_id_num = uid
uid = struct.pack('<I', uid)
if uid in self.server_info.users:
self.user_id = uid
self.user_key = self.server_info.users[uid]
self.server_info.update_user_func(uid)
else:
self.user_id_num = 0
if not self.server_info.users:
self.user_key = self.server_info.key
else:
self.user_key = self.server_info.recv_iv
md5data = hmac.new(self.user_key, self.recv_buf[12 : 12 + 20], self.hashfunc).digest()
if md5data[:4] != self.recv_buf[32:36]:
logging.error('%s data uncorrect auth HMAC-MD5 from %s:%d, data %s' % (self.no_compatible_method, self.server_info.client, self.server_info.client_port, binascii.hexlify(self.recv_buf)))
if len(self.recv_buf) < 36:
return (b'', False)
return self.not_match_return(self.recv_buf)
self.last_server_hash = md5data
encryptor = encrypt.Encryptor(to_bytes(base64.b64encode(self.user_key)) + self.salt, 'aes-128-cbc')
head = encryptor.decrypt(b'\x00' * 16 + self.recv_buf[16:32] + b'\x00') # need an extra byte or recv empty
self.client_over_head = struct.unpack('<H', head[12:14])[0]
utc_time = struct.unpack('<I', head[:4])[0]
client_id = struct.unpack('<I', head[4:8])[0]
connection_id = struct.unpack('<I', head[8:12])[0]
time_dif = common.int32(utc_time - (int(time.time()) & 0xffffffff))
if time_dif < -self.max_time_dif or time_dif > self.max_time_dif:
logging.info('%s: wrong timestamp, time_dif %d, data %s' % (self.no_compatible_method, time_dif, binascii.hexlify(head)))
return self.not_match_return(self.recv_buf)
elif self.server_info.data.insert(self.user_id, client_id, connection_id):
self.has_recv_header = True
self.client_id = client_id
self.connection_id = connection_id
else:
logging.info('%s: auth fail, data %s' % (self.no_compatible_method, binascii.hexlify(out_buf)))
return self.not_match_return(self.recv_buf)
self.encryptor = encrypt.Encryptor(to_bytes(base64.b64encode(self.user_key)) + to_bytes(base64.b64encode(self.last_client_hash)), 'rc4')
self.recv_buf = self.recv_buf[36:]
self.has_recv_header = True
sendback = True
while len(self.recv_buf) > 4:
mac_key = self.user_key + struct.pack('<I', self.recv_id)
data_len = struct.unpack('<H', self.recv_buf[:2])[0] ^ struct.unpack('<H', self.last_client_hash[14:16])[0]
rand_len = self.rnd_data_len(data_len, self.last_client_hash, self.random_client)
length = data_len + rand_len
if length >= 4096:
self.raw_trans = True
self.recv_buf = b''
if self.recv_id == 0:
logging.info(self.no_compatible_method + ': over size')
return (b'E'*2048, False)
else:
raise Exception('server_post_decrype data error')
if length + 4 > len(self.recv_buf):
break
client_hash = hmac.new(mac_key, self.recv_buf[:length + 2], self.hashfunc).digest()
if client_hash[:2] != self.recv_buf[length + 2 : length + 4]:
logging.info('%s: checksum error, data %s' % (self.no_compatible_method, binascii.hexlify(self.recv_buf[:length])))
self.raw_trans = True
self.recv_buf = b''
if self.recv_id == 0:
return (b'E'*2048, False)
else:
raise Exception('server_post_decrype data uncorrect checksum')
self.recv_id = (self.recv_id + 1) & 0xFFFFFFFF
pos = 2
if data_len > 0 and rand_len > 0:
pos = 2 + self.rnd_start_pos(rand_len, self.random_client)
out_buf += self.encryptor.decrypt(self.recv_buf[pos : data_len + pos])
self.last_client_hash = client_hash
self.recv_buf = self.recv_buf[length + 4:]
if data_len == 0:
sendback = True
if out_buf:
self.server_info.data.update(self.user_id, self.client_id, self.connection_id)
return (out_buf, sendback)
def client_udp_pre_encrypt(self, buf):
if self.user_key is None:
if b':' in to_bytes(self.server_info.protocol_param):
try:
items = to_bytes(self.server_info.protocol_param).split(':')
self.user_key = self.hashfunc(items[1]).digest()
self.user_id = struct.pack('<I', int(items[0]))
except:
pass
if self.user_key is None:
self.user_id = os.urandom(4)
self.user_key = self.server_info.key
authdata = os.urandom(3)
mac_key = self.server_info.key
md5data = hmac.new(mac_key, authdata, self.hashfunc).digest()
uid = struct.unpack('<I', self.user_id)[0] ^ struct.unpack('<I', md5data[:4])[0]
uid = struct.pack('<I', uid)
rand_len = self.udp_rnd_data_len(md5data, self.random_client)
encryptor = encrypt.Encryptor(to_bytes(base64.b64encode(self.user_key)) + to_bytes(base64.b64encode(md5data)), 'rc4')
out_buf = encryptor.encrypt(buf)
buf = out_buf + os.urandom(rand_len) + authdata + uid
return buf + hmac.new(self.user_key, buf, self.hashfunc).digest()[:1]
def client_udp_post_decrypt(self, buf):
if len(buf) <= 8:
return (b'', None)
if hmac.new(self.user_key, buf[:-1], self.hashfunc).digest()[:1] != buf[-1:]:
return (b'', None)
mac_key = self.server_info.key
md5data = hmac.new(mac_key, buf[-8:-1], self.hashfunc).digest()
rand_len = self.udp_rnd_data_len(md5data, self.random_server)
encryptor = encrypt.Encryptor(to_bytes(base64.b64encode(self.user_key)) + to_bytes(base64.b64encode(md5data)), 'rc4')
return encryptor.decrypt(buf[:-8 - rand_len])
def server_udp_pre_encrypt(self, buf, uid):
if uid in self.server_info.users:
user_key = self.server_info.users[uid]
else:
uid = None
if not self.server_info.users:
user_key = self.server_info.key
else:
user_key = self.server_info.recv_iv
authdata = os.urandom(7)
mac_key = self.server_info.key
md5data = hmac.new(mac_key, authdata, self.hashfunc).digest()
rand_len = self.udp_rnd_data_len(md5data, self.random_server)
encryptor = encrypt.Encryptor(to_bytes(base64.b64encode(user_key)) + to_bytes(base64.b64encode(md5data)), 'rc4')
out_buf = encryptor.encrypt(buf)
buf = out_buf + os.urandom(rand_len) + authdata
return buf + hmac.new(user_key, buf, self.hashfunc).digest()[:1]
def server_udp_post_decrypt(self, buf):
mac_key = self.server_info.key
md5data = hmac.new(mac_key, buf[-8:-5], self.hashfunc).digest()
uid = struct.unpack('<I', buf[-5:-1])[0] ^ struct.unpack('<I', md5data[:4])[0]
uid = struct.pack('<I', uid)
if uid in self.server_info.users:
user_key = self.server_info.users[uid]
else:
uid = None
if not self.server_info.users:
user_key = self.server_info.key
else:
user_key = self.server_info.recv_iv
if hmac.new(user_key, buf[:-1], self.hashfunc).digest()[:1] != buf[-1:]:
return (b'', None)
rand_len = self.udp_rnd_data_len(md5data, self.random_client)
encryptor = encrypt.Encryptor(to_bytes(base64.b64encode(user_key)) + to_bytes(base64.b64encode(md5data)), 'rc4')
out_buf = encryptor.decrypt(buf[:-8 - rand_len])
return (out_buf, uid)
def dispose(self):
self.server_info.data.remove(self.user_id, self.client_id)
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