1 files changed, 66 insertions, 0 deletions
diff --git a/mitmproxy/libmproxy/proxy/modes/socks_proxy.py b/mitmproxy/libmproxy/proxy/modes/socks_proxy.py
new file mode 100644
index 00000000..e2ce44ae
--- /dev/null
+++ b/mitmproxy/libmproxy/proxy/modes/socks_proxy.py
@@ -0,0 +1,66 @@
+from __future__ import (absolute_import, print_function, division)
+
+from netlib import socks, tcp
+from netlib.exceptions import TcpException
+
+from ...exceptions import Socks5ProtocolException
+from ...protocol import Layer, ServerConnectionMixin
+
+
+class Socks5Proxy(Layer, ServerConnectionMixin):
+
+    def __init__(self, ctx):
+        super(Socks5Proxy, self).__init__(ctx)
+
+    def __call__(self):
+        try:
+            # Parse Client Greeting
+            client_greet = socks.ClientGreeting.from_file(self.client_conn.rfile, fail_early=True)
+            client_greet.assert_socks5()
+            if socks.METHOD.NO_AUTHENTICATION_REQUIRED not in client_greet.methods:
+                raise socks.SocksError(
+                    socks.METHOD.NO_ACCEPTABLE_METHODS,
+                    "mitmproxy only supports SOCKS without authentication"
+                )
+
+            # Send Server Greeting
+            server_greet = socks.ServerGreeting(
+                socks.VERSION.SOCKS5,
+                socks.METHOD.NO_AUTHENTICATION_REQUIRED
+            )
+            server_greet.to_file(self.client_conn.wfile)
+            self.client_conn.wfile.flush()
+
+            # Parse Connect Request
+            connect_request = socks.Message.from_file(self.client_conn.rfile)
+            connect_request.assert_socks5()
+            if connect_request.msg != socks.CMD.CONNECT:
+                raise socks.SocksError(
+                    socks.REP.COMMAND_NOT_SUPPORTED,
+                    "mitmproxy only supports SOCKS5 CONNECT."
+                )
+
+            # We always connect lazily, but we need to pretend to the client that we connected.
+            connect_reply = socks.Message(
+                socks.VERSION.SOCKS5,
+                socks.REP.SUCCEEDED,
+                connect_request.atyp,
+                # dummy value, we don't have an upstream connection yet.
+                connect_request.addr
+            )
+            connect_reply.to_file(self.client_conn.wfile)
+            self.client_conn.wfile.flush()
+
+        except (socks.SocksError, TcpException) as e:
+            raise Socks5ProtocolException("SOCKS5 mode failure: %s" % repr(e))
+
+        # https://github.com/mitmproxy/mitmproxy/issues/839
+        address_bytes = (connect_request.addr.host.encode("idna"), connect_request.addr.port)
+        self.server_conn.address = tcp.Address(address_bytes, connect_request.addr.use_ipv6)
+
+        layer = self.ctx.next_layer(self)
+        try:
+            layer()
+        finally:
+            if self.server_conn:
+                self.disconnect()