Support redirect rule (#145)

Syntax:

match_hostname_regex:port(* means match all port)#redirect_dist_host:redirect_port

and in the config.json(user-config.json) redirect param should be a list,

for example

```
"redirect": ["*:8080#zhaoj.in:80","zhaojin97.cn:80#127.0.0.1:80","*#pku.edu.cn:80"]
```

This example means abnormal connection which connect to port 8080 will be redirected to zhaoj.in:80,and if there a http request with hostname zhaojin97.cn(you can set hosts file to test it) will be redirected to 127.0.0.1:80,and the rest of abnormal connection will be redirect to pku.edu.cn:80

shadowsocks/common.py

@@ -22,6 +22,7 @@ import socket
 import struct
 import logging
 import binascii
+import re
 
 def compat_ord(s):
     if type(s) == int:
@@ -118,6 +119,13 @@ def is_ip(address):
     return False
 
 
+def match_regex(regex, text):
+    regex = re.compile(regex)
+    for item in regex.findall(text):
+        return True
+    return False
+
+
 def patch_socket():
     if not hasattr(socket, 'inet_pton'):
         socket.inet_pton = inet_pton

shadowsocks/tcprelay.py

@@ -151,7 +151,7 @@ class TCPRelayHandler(object):
         server_info.tcp_mss = 1460
         self._protocol.set_server_info(server_info)
 
-        self._redir_list = config.get('redirect', ["0.0.0.0:0"])
+        self._redir_list = config.get('redirect', ["*#0.0.0.0:0"])
         self._bind = config.get('out_bind', '')
         self._bindv6 = config.get('out_bindv6', '')
         self._ignore_bind_list = config.get('ignore_bind', [])
@@ -347,7 +347,13 @@ class TCPRelayHandler(object):
         return True
 
     def _get_redirect_host(self, client_address, ogn_data):
-        host_list = self._redir_list or ["0.0.0.0:0"]
+        host_list = self._redir_list or ["*#0.0.0.0:0"]
+
+        if type(host_list) != list:
+            host_list = [host_list]
+
+        items_sum = common.to_str(host_list[0]).rsplit('#', 1)
+        if len(items_sum) < 2:
             hash_code = binascii.crc32(ogn_data)
             addrs = socket.getaddrinfo(client_address[0], client_address[1], 0, socket.SOCK_STREAM, socket.SOL_TCP)
             af, socktype, proto, canonname, sa = addrs[0]
@@ -361,8 +367,6 @@ class TCPRelayHandler(object):
 
             host_port = []
             match_port = False
-        if type(host_list) != list:
-            host_list = [host_list]
             for host in host_list:
                 items = common.to_str(host).rsplit(':', 1)
                 if len(items) > 1:
@@ -385,6 +389,36 @@ class TCPRelayHandler(object):
 
             return host_port[((hash_code & 0xffffffff) + addr) % len(host_port)]
 
+        else:
+            host_port = []
+            for host in host_list:
+                items_sum = common.to_str(host).rsplit('#', 1)
+                items_match = common.to_str(items_sum[0]).rsplit(':', 1)
+                items = common.to_str(items_sum[1]).rsplit(':', 1)
+                if len(items_match) > 1:
+                    if self._server._listen_port != int(items_match[1]):
+                        continue
+                match_port = 0
+                if len(items_match) > 1:
+                    if items_match[1] != "*":
+                        try:
+                            match_port = int(items_match[1])
+                        except:
+                            pass
+                if items_match[0] != "*" and common.match_regex(items_match[0], ogn_data) == False and \
+                not (match_port == self._server._listen_port or match_port == 0):
+                    continue
+                if len(items) > 1:
+                    try:
+                        port = int(items[1])
+                        return (items[0], port)
+                    except:
+                        pass
+                else:
+                    return (items[0], 80)
+
+            return ("0.0.0.0", 0)
+
     def _handel_protocol_error(self, client_address, ogn_data):
         logging.warn("Protocol ERROR, TCP ogn data %s from %s:%d via port %d" % (binascii.hexlify(ogn_data), client_address[0], client_address[1], self._server._listen_port))
         self._encrypt_correct = False