[or-cvs] r17815: {tor} Do not not cannibalize a circuit that has run out of RELAY_E (in tor/trunk: . src/or)

[nickm at seul.org]

Author: nickm
Date: 2008-12-29 14:55:17 -0500 (Mon, 29 Dec 2008)
New Revision: 17815

Modified:
   tor/trunk/ChangeLog
   tor/trunk/src/or/relay.c
Log:
Do not not cannibalize a circuit that has run out of RELAY_EARLY cells.  Partial bug 878 fix.

Modified: tor/trunk/ChangeLog
===================================================================
--- tor/trunk/ChangeLog	2008-12-29 19:55:13 UTC (rev 17814)
+++ tor/trunk/ChangeLog	2008-12-29 19:55:17 UTC (rev 17815)
@@ -18,6 +18,11 @@
       send on that circuit.  Otherwise we might violate the proposal-110
       limit.  Bugfix on 0.2.1.3-alpha.  Partial fix for Bug 878.  Diagnosis
       thanks to Karsten.
+    - When we're sending non-EXTEND cells to the first hop in a circuit
+      (for example in order to use an encrypted directory connection), we
+      don't need to use RELAY_EARLY cells: the first hop knows what kind of
+      cell it is, and nobody else can even see the cell type.  This makes
+      it easier to cannibalize circuits like this later.
 
   o Code simplifications and refactoring:
     - Change our header file guard macros to be less likely to conflict

Modified: tor/trunk/src/or/relay.c
===================================================================
--- tor/trunk/src/or/relay.c	2008-12-29 19:55:13 UTC (rev 17814)
+++ tor/trunk/src/or/relay.c	2008-12-29 19:55:17 UTC (rev 17815)
@@ -510,10 +510,13 @@
 
   if (cell_direction == CELL_DIRECTION_OUT) {
     origin_circuit_t *origin_circ = TO_ORIGIN_CIRCUIT(circ);
-    if (origin_circ->remaining_relay_early_cells > 0) {
-      /* If we've got any relay_early cells left, use one.  Don't worry
-       * about the conn protocol version: append_cell_to_circuit_queue will
-       * fix it up. */
+    if (origin_circ->remaining_relay_early_cells > 0 &&
+        (relay_command == RELAY_COMMAND_EXTEND ||
+         cpath_layer != origin_circ->cpath)) {
+      /* If we've got any relay_early cells left, and we're sending a relay
+       * cell or we're not talking to the first hop, use one of them.  Don't
+       * worry about the conn protocol version: append_cell_to_circuit_queue
+       * will fix it up. */
       cell.command = CELL_RELAY_EARLY;
       --origin_circ->remaining_relay_early_cells;
       log_debug(LD_OR, "Sending a RELAY_EARLY cell; %d remaining.",