tor: socks.port is now a (restricted) endpoint string

Foolscap has limitations that prevent us from accepting anything but a
TCP endpoint, but that will change in the future, so make the tahoe.cfg
syntax accept an endpoint, but then reject non-TCP ones. See the ticket
for details: refs ticket:2813.

This depends upon the new `foolscap.connections.tor.socks_port(host,
port)` API in foolscap-0.12.2, so it bumps the dependency to that (the
previous commit depended upon 0.12.1, but I hadn't gotten around to
updating the dep before now).

docs/configuration.rst

@@ -402,14 +402,21 @@ specify it.
     If False, this will disable the use of Tor entirely. The default of True
     means the node will use Tor, if necessary, and if possible.
 
-``socks.port = (string, optional, PORT, defaults to empty)``
+``socks.port = (string, optional, endpoint specification string, defaults to empty)``
 
     This tells the node that Tor connections should be routed to a SOCKS
-    proxy listening on the given port. The default (of an empty value) will
-    cause the node to first try localhost port 9050, then if that fails, try
-    localhost port 9150. These are the default listening ports of the
+    proxy listening on the given endpoint. The default (of an empty value)
+    will cause the node to first try localhost port 9050, then if that fails,
+    try localhost port 9150. These are the default listening ports of the
     standard Tor daemon, and the Tor Browser Bundle, respectively.
 
+    While this nominally accepts an arbitrary endpoint string, internal
+    limitations prevent it from accepting anything but ``tcp:HOST:PORT``
+    (unfortunately, unix-domain sockets are not yet supported). See ticket
+    #2813 for details. Also note that using a HOST of anything other than
+    localhost is discouraged, because you would be revealing your IP address
+    to external (and possibly hostile) machines.
+
 ``control.port = (string, optional, endpoint specification string)``
 
     This tells the node to connect to a pre-existing Tor daemon on the given
@@ -434,8 +441,8 @@ There are 5 valid combinations of these configuration settings:
 
 * 1: ``(empty)``: use SOCKS on port 9050/9150
 * 2: ``launch = true``: launch a new Tor
-* 3: ``socks.port = HOST:PORT``: use an existing Tor on the given SOCKS port
-* 4: ``control.port = PORT``: use an existing Tor at the given control port
+* 3: ``socks.port = tcp:HOST:PORT``: use an existing Tor on the given SOCKS port
+* 4: ``control.port = ENDPOINT``: use an existing Tor at the given control port
 * 5: ``enable = false``: no Tor at all
 
 1 is the default, and should work for any Linux host with the system Tor

src/allmydata/_auto_deps.py

@@ -39,7 +39,8 @@ install_requires = [
     # * foolscap 0.8.0 generates 2048-bit RSA-with-SHA-256 signatures,
     #   rather than 1024-bit RSA-with-MD5. This also allows us to work
     #   with a FIPS build of OpenSSL.
-    "foolscap >= 0.10.1",
+    # * foolscap >= 0.12.2 provides tcp/tor/i2p connection handlers we need
+    "foolscap >= 0.12.2",
 
     # Needed for SFTP.
     # pycrypto 2.2 doesn't work due to <https://bugs.launchpad.net/pycrypto/+bug/620253>

src/allmydata/node.py

@@ -187,25 +187,22 @@ class Node(service.MultiService):
 
         socksport = self.get_config("tor", "socks.port", None)
         if socksport:
-            # foolscap.connections.tor.socks_port() in Foolscap-0.12.1 only
-            # allows the use of SOCKS port on localhost, to discourage unsafe
-            # connections to remote SOCKS ports. Allow the HOST:PORT syntax,
-            # but refuse to use anything other than 127.0.0.1 . Also accept
-            # just PORT.
-            if ":" in socksport:
-                host, port = socksport.split(":")
-                if host != "127.0.0.1":
-                    raise ValueError("'tahoe.cfg [tor] socks.port' = "
-                                     "must be '127.0.0.1:PORT' or just PORT, "
-                                     "not '%s'" % (socksport,))
-            else:
-                port = socksport
+            # this is nominally and endpoint string, but txtorcon requires
+            # TCP host and port. So parse it now, and reject non-TCP
+            # endpoints.
+
+            pieces = socksport.split(":")
+            if pieces[0] != "tcp" or len(pieces) != 3:
+                raise ValueError("'tahoe.cfg [tor] socks.port' = "
+                                 "is currently limited to 'tcp:HOST:PORT', "
+                                 "not '%s'" % (socksport,))
+            host = pieces[1]
             try:
-                port = int(port)
+                port = int(pieces[2])
             except ValueError:
                 raise ValueError("'tahoe.cfg [tor] socks.port' used "
-                                 "non-numeric PORT value '%s'" % (port,))
-            return tor.socks_port(port)
+                                 "non-numeric PORT value '%s'" % (pieces[2],))
+            return tor.socks_port(host, port)
 
         controlport = self.get_config("tor", "control.port", None)
         if controlport:

src/allmydata/test/test_connections.py

@@ -65,30 +65,30 @@ class Tor(unittest.TestCase):
             self.assertIdentical(h, h1)
 
     def test_socksport(self):
-        n = FakeNode(BASECONFIG+"[tor]\nsocks.port = 1234\n")
+        n = FakeNode(BASECONFIG+"[tor]\nsocks.port = tcp:127.0.0.1:1234\n")
         h1 = mock.Mock()
         with mock.patch("foolscap.connections.tor.socks_port",
                         return_value=h1) as f:
             h = n._make_tor_handler()
-            self.assertEqual(f.mock_calls, [mock.call(1234)])
+            self.assertEqual(f.mock_calls, [mock.call("127.0.0.1", 1234)])
             self.assertIdentical(h, h1)
 
-    def test_socksport_localhost(self):
-        n = FakeNode(BASECONFIG+"[tor]\nsocks.port = 127.0.0.1:1234\n")
+    def test_socksport_otherhost(self):
+        n = FakeNode(BASECONFIG+"[tor]\nsocks.port = tcp:otherhost:1234\n")
         h1 = mock.Mock()
         with mock.patch("foolscap.connections.tor.socks_port",
                         return_value=h1) as f:
             h = n._make_tor_handler()
-            self.assertEqual(f.mock_calls, [mock.call(1234)])
+            self.assertEqual(f.mock_calls, [mock.call("otherhost", 1234)])
             self.assertIdentical(h, h1)
 
-    def test_socksport_bad_host(self):
-        n = FakeNode(BASECONFIG+"[tor]\nsocks.port = example.com:1234\n")
+    def test_socksport_bad_endpoint(self):
+        n = FakeNode(BASECONFIG+"[tor]\nsocks.port = unix:unsupported\n")
         e = self.assertRaises(ValueError, n._make_tor_handler)
-        self.assertIn("must be '127.0.0.1:PORT'", str(e))
+        self.assertIn("is currently limited to 'tcp:HOST:PORT'", str(e))
 
     def test_socksport_not_integer(self):
-        n = FakeNode(BASECONFIG+"[tor]\nsocks.port = kumquat\n")
+        n = FakeNode(BASECONFIG+"[tor]\nsocks.port = tcp:localhost:kumquat\n")
         e = self.assertRaises(ValueError, n._make_tor_handler)
         self.assertIn("used non-numeric PORT value", str(e))