table encryptor should have its own encrypt/decrypt table

shadowsocks/encrypt.py

@@ -42,11 +42,7 @@ def get_table(key):
         table.sort(lambda x, y: int(a % (ord(x) + i) - a % (ord(y) + i)))
     return table
 
-encrypt_table = None
-decrypt_table = None
-
-
-def init_table(key, method=None):
+def try_encryptor(key, method=None):
     if method == 'table':
         method = None
     if method:
@@ -56,7 +52,6 @@ def init_table(key, method=None):
             logging.error('M2Crypto is required to use encryption other than default method')
             sys.exit(1)
     if not method:
-        global encrypt_table, decrypt_table
         encrypt_table = ''.join(get_table(key))
         decrypt_table = string.maketrans(encrypt_table, string.maketrans('', ''))
     else:
@@ -118,6 +113,9 @@ class Encryptor(object):
             self.cipher = self.get_cipher(key, method, 1, iv=random_string(32))
         else:
             self.cipher = None
+            self.encrypt_table = ''.join(get_table(key))
+            self.decrypt_table = string.maketrans(self.encrypt_table, string.maketrans('', ''))
+
 
     def get_cipher_len(self, method):
         method = method.lower()
@@ -147,7 +145,7 @@ class Encryptor(object):
         if len(buf) == 0:
             return buf
         if self.method is None:
-            return string.translate(buf, encrypt_table)
+            return string.translate(buf, self.encrypt_table)
         else:
             if self.iv_sent:
                 return self.cipher.update(buf)
@@ -159,7 +157,7 @@ class Encryptor(object):
         if len(buf) == 0:
             return buf
         if self.method is None:
-            return string.translate(buf, decrypt_table)
+            return string.translate(buf, self.decrypt_table)
         else:
             if self.decipher is None:
                 decipher_iv_len = self.get_cipher_len(self.method)[1]

shadowsocks/local.py

@@ -235,7 +235,7 @@ def main():
 
     utils.check_config(config)
 
-    encrypt.init_table(KEY, METHOD)
+    encrypt.try_encryptor(KEY, METHOD)
 
     try:
         if IPv6:

shadowsocks/server.py

@@ -193,7 +193,7 @@ def main():
         PORTPASSWORD = {}
         PORTPASSWORD[str(PORT)] = KEY
 
-    encrypt.init_table(KEY, METHOD)
+    encrypt.try_encryptor(KEY, METHOD)
     if IPv6:
         ThreadingTCPServer.address_family = socket.AF_INET6
     for port, key in PORTPASSWORD.items():