Ensure controller RESOLVE commands respect __LeaveStreamsUnattached

https://trac.torproject.org/projects/tor/ticket/1525

"The codepath taken by the control port "RESOLVE" command to create a
synthetic SOCKS resolve request isn't the same as the path taken by
a real SOCKS request from 'tor-resolve'.
This prevents controllers who set LeaveStreamsUnattached=1 from
being able to attach RESOLVE streams to circuits of their choosing."

Create a new function connection_ap_rewrite_and_attach_if_allowed()
and call that when Tor needs to attach a stream to a circuit but
needs to know if the controller permits it.

No tests added.

3 files changed, 35 insertions, 27 deletions

diff --git a/src/or/connection_edge.c b/src/or/connection_edge.c
index 7522368c56..365a7972e3 100644
--- a/src/or/connection_edge.c
+++ b/src/or/connection_edge.c
@@ -1408,6 +1408,23 @@ consider_plaintext_ports(edge_connection_t *conn, uint16_t port)
  * different one? */
 #define TRACKHOSTEXITS_RETRIES 5
 
+/** Call connection_ap_handshake_rewrite_and_attach() unless a controller
+ *  asked us to leave streams unattached.
+ */
+int
+connection_ap_rewrite_and_attach_if_allowed(edge_connection_t *conn,
+                                            origin_circuit_t *circ,
+                                            crypt_path_t *cpath)
+{
+  or_options_t *options = get_options();
+
+  if (options->LeaveStreamsUnattached) {
+    conn->_base.state = AP_CONN_STATE_CONTROLLER_WAIT;
+    return 0;
+  }
+  return connection_ap_handshake_rewrite_and_attach(conn, circ, cpath);
+}
+
 /** Connection <b>conn</b> just finished its socks handshake, or the
  * controller asked us to take care of it. If <b>circ</b> is defined,
  * then that's where we'll want to attach it. Otherwise we have to
@@ -1908,11 +1925,7 @@ connection_ap_handshake_process_socks(edge_connection_t *conn)
   else
     control_event_stream_status(conn, STREAM_EVENT_NEW_RESOLVE, 0);
 
-  if (options->LeaveStreamsUnattached) {
-    conn->_base.state = AP_CONN_STATE_CONTROLLER_WAIT;
-    return 0;
-  }
-  return connection_ap_handshake_rewrite_and_attach(conn, NULL, NULL);
+  return connection_ap_rewrite_and_attach_if_allowed(conn, NULL, NULL);
 }
 
 /** connection_init_accepted_conn() found a new trans AP conn.
@@ -1926,7 +1939,6 @@ int
 connection_ap_process_transparent(edge_connection_t *conn)
 {
   socks_request_t *socks;
-  or_options_t *options = get_options();
 
   tor_assert(conn);
   tor_assert(conn->_base.type == CONN_TYPE_AP);
@@ -1950,11 +1962,7 @@ connection_ap_process_transparent(edge_connection_t *conn)
 
   control_event_stream_status(conn, STREAM_EVENT_NEW, 0);
 
-  if (options->LeaveStreamsUnattached) {
-    conn->_base.state = AP_CONN_STATE_CONTROLLER_WAIT;
-    return 0;
-  }
-  return connection_ap_handshake_rewrite_and_attach(conn, NULL, NULL);
+  return connection_ap_rewrite_and_attach_if_allowed(conn, NULL, NULL);
 }
 
 /** connection_edge_process_inbuf() found a conn in state natd_wait. See if
@@ -1975,7 +1983,6 @@ connection_ap_process_natd(edge_connection_t *conn)
   size_t tlen = 30;
   int err, port_ok;
   socks_request_t *socks;
-  or_options_t *options = get_options();
 
   tor_assert(conn);
   tor_assert(conn->_base.type == CONN_TYPE_AP);
@@ -2031,13 +2038,9 @@ connection_ap_process_natd(edge_connection_t *conn)
 
   control_event_stream_status(conn, STREAM_EVENT_NEW, 0);
 
-  if (options->LeaveStreamsUnattached) {
-    conn->_base.state = AP_CONN_STATE_CONTROLLER_WAIT;
-    return 0;
-  }
   conn->_base.state = AP_CONN_STATE_CIRCUIT_WAIT;
 
-  return connection_ap_handshake_rewrite_and_attach(conn, NULL, NULL);
+  return connection_ap_rewrite_and_attach_if_allowed(conn, NULL, NULL);
 }
 
 /** Iterate over the two bytes of stream_id until we get one that is not
diff --git a/src/or/connection_edge.h b/src/or/connection_edge.h
index c3d6098c5a..85444503b8 100644
--- a/src/or/connection_edge.h
+++ b/src/or/connection_edge.h
@@ -79,6 +79,9 @@ void client_dns_set_addressmap(const char *address, uint32_t val,
 const char *addressmap_register_virtual_address(int type, char *new_address);
 void addressmap_get_mappings(smartlist_t *sl, time_t min_expires,
                              time_t max_expires, int want_expiry);
+int connection_ap_rewrite_and_attach_if_allowed(edge_connection_t *conn,
+                                                origin_circuit_t *circ,
+                                                crypt_path_t *cpath);
 int connection_ap_handshake_rewrite_and_attach(edge_connection_t *conn,
                                                origin_circuit_t *circ,
                                                crypt_path_t *cpath);
diff --git a/src/or/dnsserv.c b/src/or/dnsserv.c
index e231b655f4..ad4f4122bc 100644
--- a/src/or/dnsserv.c
+++ b/src/or/dnsserv.c
@@ -141,16 +141,17 @@ evdns_server_callback(struct evdns_server_request *req, void *_data)
 
   control_event_stream_status(conn, STREAM_EVENT_NEW, 0);
 
-  /* Now, throw the connection over to get rewritten (which will answer it
-  * immediately if it's in the cache, or completely bogus, or automapped),
-  * and then attached to a circuit. */
+  /* Now, unless a controller asked us to leave streams unattached,
+  * throw the connection over to get rewritten (which will
+  * answer it immediately if it's in the cache, or completely bogus, or
+  * automapped), and then attached to a circuit. */
   log_info(LD_APP, "Passing request for %s to rewrite_and_attach.",
            escaped_safe_str_client(q->name));
   q_name = tor_strdup(q->name); /* q could be freed in rewrite_and_attach */
-  connection_ap_handshake_rewrite_and_attach(conn, NULL, NULL);
+  connection_ap_rewrite_and_attach_if_allowed(conn, NULL, NULL);
   /* Now, the connection is marked if it was bad. */
 
-  log_info(LD_APP, "Passed request for %s to rewrite_and_attach.",
+  log_info(LD_APP, "Passed request for %s to rewrite_and_attach_if_allowed.",
            escaped_safe_str_client(q_name));
   tor_free(q_name);
 }
@@ -186,16 +187,17 @@ dnsserv_launch_request(const char *name, int reverse)
     return -1;
   }
 
-  /* Now, throw the connection over to get rewritten (which will answer it
-  * immediately if it's in the cache, or completely bogus, or automapped),
-  * and then attached to a circuit. */
+  /* Now, unless a controller asked us to leave streams unattached,
+  * throw the connection over to get rewritten (which will
+  * answer it immediately if it's in the cache, or completely bogus, or
+  * automapped), and then attached to a circuit. */
   log_info(LD_APP, "Passing request for %s to rewrite_and_attach.",
            escaped_safe_str_client(name));
   q_name = tor_strdup(name); /* q could be freed in rewrite_and_attach */
-  connection_ap_handshake_rewrite_and_attach(conn, NULL, NULL);
+  connection_ap_rewrite_and_attach_if_allowed(conn, NULL, NULL);
   /* Now, the connection is marked if it was bad. */
 
-  log_info(LD_APP, "Passed request for %s to rewrite_and_attach.",
+  log_info(LD_APP, "Passed request for %s to rewrite_and_attach_if_allowed.",
            escaped_safe_str_client(q_name));
   tor_free(q_name);
   return 0;