Correctly update channel local mark when address of incoming connection changes after handshake; fixes bug #12160

changes/bug12160

@@ -0,0 +1,4 @@
+ o Bugfixes
+   - Correctly update the local mark on the controlling channel when changing
+     the address of an or_connection_t after the handshake.  Fixes bug #12160;
+     bugfix on 0.2.4.4-alpha.

src/or/channel.c

@@ -3759,6 +3759,23 @@ channel_mark_local(channel_t *chan)
   chan->is_local = 1;
 }
 
+/**
+ * Mark a channel as remote
+ *
+ * This internal-only function should be called by the lower layer if the
+ * channel is not to a local address but has previously been marked local.
+ * See channel_is_local() above or the description of the is_local bit in
+ * channel.h
+ */
+
+void
+channel_mark_remote(channel_t *chan)
+{
+  tor_assert(chan);
+
+  chan->is_local = 0;
+}
+
 /**
  * Test outgoing flag
  *

src/or/channel.h

@@ -349,6 +349,7 @@ void channel_clear_remote_end(channel_t *chan);
 void channel_mark_local(channel_t *chan);
 void channel_mark_incoming(channel_t *chan);
 void channel_mark_outgoing(channel_t *chan);
+void channel_mark_remote(channel_t *chan);
 void channel_set_identity_digest(channel_t *chan,
                                  const char *identity_digest);
 void channel_set_remote_end(channel_t *chan,

src/or/channeltls.c

@@ -156,7 +156,18 @@ channel_tls_connect(const tor_addr_t *addr, uint16_t port,
             tlschan,
             U64_PRINTF_ARG(chan->global_identifier));
 
-  if (is_local_addr(addr)) channel_mark_local(chan);
+  if (is_local_addr(addr)) {
+    log_debug(LD_CHANNEL,
+              "Marking new outgoing channel " U64_FORMAT " at %p as local",
+              U64_PRINTF_ARG(chan->global_identifier), chan);
+    channel_mark_local(chan);
+  } else {
+    log_debug(LD_CHANNEL,
+              "Marking new outgoing channel " U64_FORMAT " at %p as remote",
+              U64_PRINTF_ARG(chan->global_identifier), chan);
+    channel_mark_remote(chan);
+  }
+
   channel_mark_outgoing(chan);
 
   /* Set up or_connection stuff */
@@ -286,7 +297,18 @@ channel_tls_handle_incoming(or_connection_t *orconn)
   tlschan->conn = orconn;
   orconn->chan = tlschan;
 
-  if (is_local_addr(&(TO_CONN(orconn)->addr))) channel_mark_local(chan);
+  if (is_local_addr(&(TO_CONN(orconn)->addr))) {
+    log_debug(LD_CHANNEL,
+              "Marking new incoming channel " U64_FORMAT " at %p as local",
+              U64_PRINTF_ARG(chan->global_identifier), chan);
+    channel_mark_local(chan);
+  } else {
+    log_debug(LD_CHANNEL,
+              "Marking new incoming channel " U64_FORMAT " at %p as remote",
+              U64_PRINTF_ARG(chan->global_identifier), chan);
+    channel_mark_remote(chan);
+  }
+
   channel_mark_incoming(chan);
 
   /* Register it */
@@ -1208,6 +1230,44 @@ channel_tls_handle_var_cell(var_cell_t *var_cell, or_connection_t *conn)
   }
 }
 
+/**
+ * Update channel marks after connection_or.c has changed an address
+ *
+ * This is called from connection_or_init_conn_from_address() after the
+ * connection's _base.addr or real_addr fields have potentially been changed
+ * so we can recalculate the local mark.  Notably, this happens when incoming
+ * connections are reverse-proxied and we only learn the real address of the
+ * remote router by looking it up in the consensus after we finish the
+ * handshake and know an authenticated identity digest.
+ */
+
+void
+channel_tls_update_marks(or_connection_t *conn)
+{
+  channel_t *chan = NULL;
+
+  tor_assert(conn);
+  tor_assert(conn->chan);
+
+  chan = TLS_CHAN_TO_BASE(conn->chan);
+
+  if (is_local_addr(&(TO_CONN(conn)->addr))) {
+    if (!channel_is_local(chan)) {
+      log_debug(LD_CHANNEL,
+                "Marking channel " U64_FORMAT " at %p as local",
+                U64_PRINTF_ARG(chan->global_identifier), chan);
+      channel_mark_local(chan);
+    }
+  } else {
+    if (channel_is_local(chan)) {
+      log_debug(LD_CHANNEL,
+                "Marking channel " U64_FORMAT " at %p as remote",
+                U64_PRINTF_ARG(chan->global_identifier), chan);
+      channel_mark_remote(chan);
+    }
+  }
+}
+
 /**
  * Check if this cell type is allowed before the handshake is finished
  *

src/or/channeltls.h

@@ -49,6 +49,7 @@ void channel_tls_handle_state_change_on_orconn(channel_tls_t *chan,
                                                uint8_t state);
 void channel_tls_handle_var_cell(var_cell_t *var_cell,
                                  or_connection_t *conn);
+void channel_tls_update_marks(or_connection_t *conn);
 
 /* Cleanup at shutdown */
 void channel_tls_free_all(void);

src/or/connection_or.c

@@ -923,6 +923,15 @@ connection_or_init_conn_from_address(or_connection_t *conn,
     tor_free(conn->base_.address);
     conn->base_.address = tor_dup_addr(addr);
   }
+
+  /*
+   * We have to tell channeltls.c to update the channel marks (local, in
+   * particular), since we may have changed the address.
+   */
+
+  if (conn->chan) {
+    channel_tls_update_marks(conn);
+  }
 }
 
 /** These just pass all the is_bad_for_new_circs manipulation on to