From 397990534a4d1d5c8823884bd73b4a028c5e1660 Mon Sep 17 00:00:00 2001
From: BreakWa11 <mmgac001@gmail.com>
Date: Tue, 19 Jan 2016 20:37:40 +0800
Subject: [PATCH] add plugin "auth_sha1_v2"

---
 shadowsocks/lru_cache.py       |   4 +
 shadowsocks/obfsplugin/auth.py | 248 ++++++++++++++++++++++++++++++++-
 2 files changed, 251 insertions(+), 1 deletion(-)

diff --git a/shadowsocks/lru_cache.py b/shadowsocks/lru_cache.py
index 648b5a3..e50d0b5 100644
--- a/shadowsocks/lru_cache.py
+++ b/shadowsocks/lru_cache.py
@@ -80,6 +80,10 @@ class LRUCache(collections.MutableMapping):
     def __len__(self):
         return len(self._store)
 
+    def first(self):
+        if len(self._keys_to_last_time) > 0:
+            return iter(self._keys_to_last_time).next()
+
     def sweep(self):
         # O(n - m)
         now = time.time()
diff --git a/shadowsocks/obfsplugin/auth.py b/shadowsocks/obfsplugin/auth.py
index 14cff5d..16bfc16 100644
--- a/shadowsocks/obfsplugin/auth.py
+++ b/shadowsocks/obfsplugin/auth.py
@@ -32,7 +32,7 @@ import hmac
 import hashlib
 
 import shadowsocks
-from shadowsocks import common
+from shadowsocks import common, lru_cache
 from shadowsocks.obfsplugin import plain
 from shadowsocks.common import to_bytes, to_str, ord, chr
 
@@ -42,10 +42,15 @@ def create_auth_simple(method):
 def create_auth_sha1(method):
     return auth_sha1(method)
 
+def create_auth_sha1_v2(method):
+    return auth_sha1_v2(method)
+
 obfs_map = {
         'auth_simple': (create_auth_simple,),
         'auth_sha1': (create_auth_sha1,),
         'auth_sha1_compatible': (create_auth_sha1,),
+        'auth_sha1_v2': (create_auth_sha1_v2,),
+        'auth_sha1_v2_compatible': (create_auth_sha1_v2,),
 }
 
 def match_begin(str1, str2):
@@ -526,3 +531,244 @@ class auth_sha1(verify_base):
             self.decrypt_packet_num += 1
         return out_buf
 
+class obfs_auth_v2_data(object):
+    def __init__(self):
+        self.client_id = lru_cache.LRUCache()
+        self.local_client_id = b''
+        self.connection_id = 0
+        self.set_max_client(64) # max active client count
+
+    def update(self, client_id, connection_id):
+        if client_id in self.client_id:
+            self.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, client_id, connection_id):
+        if self.client_id.get(client_id, None) is None or not self.client_id[client_id].enable:
+            if self.client_id.first() is None or len(self.client_id) < self.max_client:
+                if client_id not in self.client_id:
+                    #TODO: check
+                    self.client_id[client_id] = client_queue(connection_id)
+                else:
+                    self.client_id[client_id].re_enable(connection_id)
+                return self.client_id[client_id].insert(connection_id)
+
+            if not self.client_id[self.client_id.first()].is_active():
+                del self.client_id[self.client_id.first()]
+                if client_id not in self.client_id:
+                    #TODO: check
+                    self.client_id[client_id] = client_queue(connection_id)
+                else:
+                    self.client_id[client_id].re_enable(connection_id)
+                return self.client_id[client_id].insert(connection_id)
+
+            logging.warn('auth_sha1_v2: no inactive client')
+            return False
+        else:
+            return self.client_id[client_id].insert(connection_id)
+
+class auth_sha1_v2(verify_base):
+    def __init__(self, method):
+        super(auth_sha1_v2, self).__init__(method)
+        self.recv_buf = b''
+        self.unit_len = 8100
+        self.decrypt_packet_num = 0
+        self.raw_trans = False
+        self.has_sent_header = False
+        self.has_recv_header = False
+        self.client_id = 0
+        self.connection_id = 0
+
+    def init_data(self):
+        return obfs_auth_v2_data()
+
+    def set_server_info(self, server_info):
+        self.server_info = server_info
+        try:
+            max_client = int(server_info.protocol_param)
+        except:
+            max_client = 64
+        self.server_info.data.set_max_client(max_client)
+
+    def rnd_data(self, buf_size):
+        if buf_size > 1500:
+            return b'\x01'
+
+        if buf_size > 400:
+            rnd_data = os.urandom(common.ord(os.urandom(1)[0]) % 128)
+            return common.chr(len(rnd_data) + 1) + rnd_data
+
+        rnd_data = os.urandom(struct.unpack('>H', os.urandom(2))[0] % 1024)
+        return common.chr(255) + struct.pack('>H', len(rnd_data) + 3) + rnd_data
+
+    def pack_data(self, buf):
+        if len(buf) == 0:
+            return b''
+        data = self.rnd_data(len(buf)) + buf
+        data = struct.pack('>H', len(data) + 6) + data
+        adler32 = zlib.adler32(data) & 0xFFFFFFFF
+        data += struct.pack('<I', adler32)
+        return data
+
+    def pack_auth_data(self, buf):
+        if len(buf) == 0:
+            return b''
+        data = self.rnd_data(len(buf)) + buf
+        data = struct.pack('>H', len(data) + 16) + data
+        crc = binascii.crc32(self.server_info.key) & 0xFFFFFFFF
+        data = struct.pack('<I', crc) + data
+        data += hmac.new(self.server_info.iv + self.server_info.key, data, hashlib.sha1).digest()[:10]
+        return data
+
+    def auth_data(self):
+        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(8)
+            logging.debug("local_client_id %s" % (binascii.hexlify(self.server_info.data.local_client_id),))
+            self.server_info.data.connection_id = struct.unpack('<Q', self.server_info.data.local_client_id)[0] % 0xFFFFFD
+        self.server_info.data.connection_id += 1
+        return b''.join([self.server_info.data.local_client_id,
+                struct.pack('<I', self.server_info.data.connection_id)])
+
+    def client_pre_encrypt(self, buf):
+        ret = b''
+        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_data(buf[:self.unit_len])
+            buf = buf[self.unit_len:]
+        ret += self.pack_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) > 2:
+            length = struct.unpack('>H', self.recv_buf[:2])[0]
+            if length >= 8192 or length < 7:
+                self.raw_trans = True
+                self.recv_buf = b''
+                raise Exception('client_post_decrypt data error')
+            if length > len(self.recv_buf):
+                break
+
+            if struct.pack('<I', zlib.adler32(self.recv_buf[:length - 4]) & 0xFFFFFFFF) != self.recv_buf[length - 4:length]:
+                self.raw_trans = True
+                self.recv_buf = b''
+                raise Exception('client_post_decrypt data uncorrect checksum')
+
+            pos = common.ord(self.recv_buf[2])
+            if pos < 255:
+                pos += 2
+            else:
+                pos = struct.unpack('>H', self.recv_buf[3:5])[0] + 2
+            out_buf += self.recv_buf[pos:length - 4]
+            self.recv_buf = self.recv_buf[length:]
+
+        if out_buf:
+            self.decrypt_packet_num += 1
+        return out_buf
+
+    def server_pre_encrypt(self, buf):
+        if self.raw_trans:
+            return buf
+        ret = b''
+        while len(buf) > self.unit_len:
+            ret += self.pack_data(buf[:self.unit_len])
+            buf = buf[self.unit_len:]
+        ret += self.pack_data(buf)
+        return ret
+
+    def server_post_decrypt(self, buf):
+        if self.raw_trans:
+            return buf
+        self.recv_buf += buf
+        out_buf = b''
+        if not self.has_recv_header:
+            if len(self.recv_buf) < 4:
+                return b''
+            crc = struct.pack('<I', binascii.crc32(self.server_info.key) & 0xFFFFFFFF)
+            if crc != self.recv_buf[:4]:
+                if self.method == 'auth_sha1_v2':
+                    return b'E'
+                else:
+                    self.raw_trans = True
+                    return self.recv_buf
+            length = struct.unpack('>H', self.recv_buf[4:6])[0]
+            if length > len(self.recv_buf):
+                return b''
+            sha1data = hmac.new(self.server_info.recv_iv + self.server_info.key, self.recv_buf[:length - 10], hashlib.sha1).digest()[:10]
+            if sha1data != self.recv_buf[length - 10:length]:
+                logging.error('auth_sha1_v2 data uncorrect auth HMAC-SHA1')
+                return b'E'
+            pos = common.ord(self.recv_buf[6])
+            if pos < 255:
+                pos += 6
+            else:
+                pos = struct.unpack('>H', self.recv_buf[7:9])[0] + 6
+            out_buf = self.recv_buf[pos:length - 10]
+            if len(out_buf) < 8:
+                self.raw_trans = True
+                self.recv_buf = b''
+                logging.info('auth_sha1_v2: too short')
+                return b'E'
+            client_id = struct.unpack('<Q', out_buf[:8])[0]
+            connection_id = struct.unpack('<I', out_buf[8:12])[0]
+            if self.server_info.data.insert(client_id, connection_id):
+                self.has_recv_header = True
+                out_buf = out_buf[12:]
+                self.client_id = client_id
+                self.connection_id = connection_id
+            else:
+                self.raw_trans = True
+                self.recv_buf = b''
+                logging.info('auth_sha1_v2: auth fail, data %s' % (binascii.hexlify(out_buf),))
+                return b'E'
+            self.recv_buf = self.recv_buf[length:]
+            self.has_recv_header = True
+
+        while len(self.recv_buf) > 2:
+            length = struct.unpack('>H', self.recv_buf[:2])[0]
+            if length >= 8192 or length < 7:
+                self.raw_trans = True
+                self.recv_buf = b''
+                if self.decrypt_packet_num == 0:
+                    logging.info('auth_sha1_v2: over size')
+                    return b'E'
+                else:
+                    raise Exception('server_post_decrype data error')
+            if length > len(self.recv_buf):
+                break
+
+            if struct.pack('<I', zlib.adler32(self.recv_buf[:length - 4]) & 0xFFFFFFFF) != self.recv_buf[length - 4:length]:
+                logging.info('auth_sha1: checksum error, data %s' % (binascii.hexlify(self.recv_buf[:length]),))
+                self.raw_trans = True
+                self.recv_buf = b''
+                if self.decrypt_packet_num == 0:
+                    return b'E'
+                else:
+                    raise Exception('server_post_decrype data uncorrect checksum')
+
+            pos = common.ord(self.recv_buf[2])
+            if pos < 255:
+                pos += 2
+            else:
+                pos = struct.unpack('>H', self.recv_buf[3:5])[0] + 2
+            out_buf += self.recv_buf[pos:length - 4]
+            self.recv_buf = self.recv_buf[length:]
+
+        if out_buf:
+            self.server_info.data.update(self.client_id, self.connection_id)
+            self.decrypt_packet_num += 1
+        return out_buf
+