[tor-commits] [tor/master] Add a new GUARD_WAIT state for circuits

[nickm at torproject.org]

commit 238828c92b1cc186577e44490caf4fa3870e724d
Author: Nick Mathewson <nickm at torproject.org>
Date:   Mon Nov 21 16:59:00 2016 -0500

    Add a new GUARD_WAIT state for circuits
    
    This state corresponds to the WAITING_FOR_BETTER_GUARD state; it's
    for circuits that are 100% constructed, but which we won't use until
    we are sure that we wouldn't use circuits with a better guard.
---
 src/or/circuitlist.c | 20 ++++++++++++++++----
 src/or/control.c     |  5 ++++-
 src/or/or.h          |  6 +++++-
 3 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/src/or/circuitlist.c b/src/or/circuitlist.c
index f13126d..0189412 100644
--- a/src/or/circuitlist.c
+++ b/src/or/circuitlist.c
@@ -439,7 +439,13 @@ circuit_set_state(circuit_t *circ, uint8_t state)
     /* add to waiting-circuit list. */
     smartlist_add(circuits_pending_chans, circ);
   }
-  if (state == CIRCUIT_STATE_OPEN)
+  if (circ->state == CIRCUIT_STATE_GUARD_WAIT) {
+    smartlist_remove(circuits_pending_other_guards, circ);
+  }
+  if (state == CIRCUIT_STATE_GUARD_WAIT) {
+    smartlist_add(circuits_pending_other_guards, circ);
+  }
+  if (state == CIRCUIT_STATE_GUARD_WAIT || state == CIRCUIT_STATE_OPEN)
     tor_assert(!circ->n_chan_create_cell);
   circ->state = state;
 }
@@ -542,6 +548,8 @@ circuit_state_to_string(int state)
     case CIRCUIT_STATE_BUILDING: return "doing handshakes";
     case CIRCUIT_STATE_ONIONSKIN_PENDING: return "processing the onion";
     case CIRCUIT_STATE_CHAN_WAIT: return "connecting to server";
+    case CIRCUIT_STATE_GUARD_WAIT: return "waiting to see how other "
+      "guards perform";
     case CIRCUIT_STATE_OPEN: return "open";
     default:
       log_warn(LD_BUG, "Unknown circuit state %d", state);
@@ -1868,7 +1876,8 @@ circuit_about_to_free(circuit_t *circ)
    * module then.  If it isn't OPEN, we send it there now to remember which
    * links worked and which didn't.
    */
-  if (circ->state != CIRCUIT_STATE_OPEN) {
+  if (circ->state != CIRCUIT_STATE_OPEN &&
+      circ->state != CIRCUIT_STATE_GUARD_WAIT) {
     if (CIRCUIT_IS_ORIGIN(circ)) {
       origin_circuit_t *ocirc = TO_ORIGIN_CIRCUIT(circ);
       circuit_build_failed(ocirc); /* take actions if necessary */
@@ -1881,7 +1890,9 @@ circuit_about_to_free(circuit_t *circ)
   }
   if (CIRCUIT_IS_ORIGIN(circ)) {
     control_event_circuit_status(TO_ORIGIN_CIRCUIT(circ),
-     (circ->state == CIRCUIT_STATE_OPEN)?CIRC_EVENT_CLOSED:CIRC_EVENT_FAILED,
+     (circ->state == CIRCUIT_STATE_OPEN ||
+      circ->state == CIRCUIT_STATE_GUARD_WAIT) ?
+                                 CIRC_EVENT_CLOSED:CIRC_EVENT_FAILED,
      orig_reason);
   }
 
@@ -2403,7 +2414,8 @@ assert_circuit_ok(const circuit_t *c)
 
   tor_assert(c->deliver_window >= 0);
   tor_assert(c->package_window >= 0);
-  if (c->state == CIRCUIT_STATE_OPEN) {
+  if (c->state == CIRCUIT_STATE_OPEN ||
+      c->state == CIRCUIT_STATE_GUARD_WAIT) {
     tor_assert(!c->n_chan_create_cell);
     if (or_circ) {
       tor_assert(or_circ->n_crypto);
diff --git a/src/or/control.c b/src/or/control.c
index 1d7ec1b..9cc99b6 100644
--- a/src/or/control.c
+++ b/src/or/control.c
@@ -2596,6 +2596,8 @@ getinfo_helper_events(control_connection_t *control_conn,
 
       if (circ->base_.state == CIRCUIT_STATE_OPEN)
         state = "BUILT";
+      else if (circ->base_.state == CIRCUIT_STATE_GUARD_WAIT)
+        state = "GUARD_WAIT"; // XXXX prop271 must specify this.
       else if (circ->cpath)
         state = "EXTENDED";
       else
@@ -3379,7 +3381,8 @@ handle_control_extendcircuit(control_connection_t *conn, uint32_t len,
       goto done;
     }
   } else {
-    if (circ->base_.state == CIRCUIT_STATE_OPEN) {
+    if (circ->base_.state == CIRCUIT_STATE_OPEN ||
+        circ->base_.state == CIRCUIT_STATE_GUARD_WAIT) {
       int err_reason = 0;
       circuit_set_state(TO_CIRCUIT(circ), CIRCUIT_STATE_BUILDING);
       if ((err_reason = circuit_send_next_onion_skin(circ)) < 0) {
diff --git a/src/or/or.h b/src/or/or.h
index 4bc8066..eb0025d 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -438,8 +438,12 @@ typedef enum {
 /** Circuit state: I'd like to deliver a create, but my n_chan is still
  * connecting. */
 #define CIRCUIT_STATE_CHAN_WAIT 2
+/** Circuit state: the circuit is open but we don't want to actually use it
+ * until we find out if a better guard will be available.
+ */
+#define CIRCUIT_STATE_GUARD_WAIT 3
 /** Circuit state: onionskin(s) processed, ready to send/receive cells. */
-#define CIRCUIT_STATE_OPEN 3
+#define CIRCUIT_STATE_OPEN 4
 
 #define CIRCUIT_PURPOSE_MIN_ 1