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[tor-commits] [tor/master] Implement a placeholder mechanism in the channel, id->circ map
commit 967503c12c46f1c75209622ebddd15242e8af79a
Author: Nick Mathewson <nickm@xxxxxxxxxxxxxx>
Date: Thu Mar 14 12:13:45 2013 -0400
Implement a placeholder mechanism in the channel,id->circ map
We'll use this to help fix bug 7912, by providing a way to mark
that a circuit ID can't get reused while a DESTROY is queued but not sent.
---
src/or/circuitlist.c | 81 +++++++++++++++++++++++++++++++++++++++++++++-----
src/or/circuitlist.h | 2 ++
2 files changed, 76 insertions(+), 7 deletions(-)
diff --git a/src/or/circuitlist.c b/src/or/circuitlist.c
index 1903fbe..9bdf2ad 100644
--- a/src/or/circuitlist.c
+++ b/src/or/circuitlist.c
@@ -207,6 +207,61 @@ circuit_set_circid_chan_helper(circuit_t *circ, int direction,
}
}
+/** Mark that circuit id <b>id</b> shouldn't be used on channel <b>chan</b>,
+ * even if there is no circuit on the channel. We use this to keep the
+ * circuit id from getting re-used while we have queued but not yet sent
+ * a destroy cell. */
+void
+channel_mark_circid_unusable(channel_t *chan, circid_t id)
+{
+ chan_circid_circuit_map_t search;
+ chan_circid_circuit_map_t *ent;
+
+ /* See if there's an entry there. That wouldn't be good. */
+ memset(&search, 0, sizeof(search));
+ search.chan = chan;
+ search.circ_id = id;
+ ent = HT_FIND(chan_circid_map, &chan_circid_map, &search);
+
+ if (ent && ent->circuit) {
+ /* we have a problem. */
+ log_warn(LD_BUG, "Tried to mark %u unusable on %p, but there was already "
+ "a circuit there.", (unsigned)id, chan);
+ } else if (ent) {
+ /* It's already marked. */
+ } else {
+ ent = tor_malloc_zero(sizeof(chan_circid_circuit_map_t));
+ ent->chan = chan;
+ ent->circ_id = id;
+ /* leave circuit at NULL */
+ HT_INSERT(chan_circid_map, &chan_circid_map, ent);
+ }
+}
+
+/** Mark that a circuit id <b>id</b> can be used again on <b>chan</b>.
+ * We use this to re-enable the circuit ID after we've sent a destroy cell.
+ */
+void
+channel_mark_circid_usable(channel_t *chan, circid_t id)
+{
+ chan_circid_circuit_map_t search;
+ chan_circid_circuit_map_t *ent;
+
+ /* See if there's an entry there. That wouldn't be good. */
+ memset(&search, 0, sizeof(search));
+ search.chan = chan;
+ search.circ_id = id;
+ ent = HT_REMOVE(chan_circid_map, &chan_circid_map, &search);
+ if (ent && ent->circuit) {
+ log_warn(LD_BUG, "Tried to mark %u usable on %p, but there was already "
+ "a circuit there.", (unsigned)id, chan);
+ return;
+ }
+ if (_last_circid_chan_ent == ent)
+ _last_circid_chan_ent = NULL;
+ tor_free(ent);
+}
+
/** Set the p_conn field of a circuit <b>circ</b>, along
* with the corresponding circuit ID, and add the circuit as appropriate
* to the (chan,id)-\>circuit map. */
@@ -928,9 +983,13 @@ circuit_get_by_global_id(uint32_t id)
* - circ-\>n_circ_id or circ-\>p_circ_id is equal to <b>circ_id</b>, and
* - circ is attached to <b>chan</b>, either as p_chan or n_chan.
* Return NULL if no such circuit exists.
+ *
+ * If <b>found_entry_out</b> is provided, set it to true if we have a
+ * placeholder entry for circid/chan, and leave it unset otherwise.
*/
static INLINE circuit_t *
-circuit_get_by_circid_channel_impl(circid_t circ_id, channel_t *chan)
+circuit_get_by_circid_channel_impl(circid_t circ_id, channel_t *chan,
+ int *found_entry_out)
{
chan_circid_circuit_map_t search;
chan_circid_circuit_map_t *found;
@@ -951,15 +1010,21 @@ circuit_get_by_circid_channel_impl(circid_t circ_id, channel_t *chan)
" circ_id %u, channel ID " U64_FORMAT " (%p)",
found->circuit, (unsigned)circ_id,
U64_PRINTF_ARG(chan->global_identifier), chan);
+ if (found_entry_out)
+ *found_entry_out = 1;
return found->circuit;
}
log_debug(LD_CIRC,
- "circuit_get_by_circid_channel_impl() found nothing for"
+ "circuit_get_by_circid_channel_impl() found %s for"
" circ_id %u, channel ID " U64_FORMAT " (%p)",
+ found ? "placeholder" : "nothing",
(unsigned)circ_id,
U64_PRINTF_ARG(chan->global_identifier), chan);
+ if (found_entry_out)
+ *found_entry_out = found ? 1 : 0;
+
return NULL;
/* The rest of this checks for bugs. Disabled by default. */
/* We comment it out because coverity complains otherwise.
@@ -993,7 +1058,7 @@ circuit_get_by_circid_channel_impl(circid_t circ_id, channel_t *chan)
circuit_t *
circuit_get_by_circid_channel(circid_t circ_id, channel_t *chan)
{
- circuit_t *circ = circuit_get_by_circid_channel_impl(circ_id, chan);
+ circuit_t *circ = circuit_get_by_circid_channel_impl(circ_id, chan, NULL);
if (!circ || circ->marked_for_close)
return NULL;
else
@@ -1009,7 +1074,7 @@ circuit_t *
circuit_get_by_circid_channel_even_if_marked(circid_t circ_id,
channel_t *chan)
{
- return circuit_get_by_circid_channel_impl(circ_id, chan);
+ return circuit_get_by_circid_channel_impl(circ_id, chan, NULL);
}
/** Return true iff the circuit ID <b>circ_id</b> is currently used by a
@@ -1017,7 +1082,9 @@ circuit_get_by_circid_channel_even_if_marked(circid_t circ_id,
int
circuit_id_in_use_on_channel(circid_t circ_id, channel_t *chan)
{
- return circuit_get_by_circid_channel_impl(circ_id, chan) != NULL;
+ int found = 0;
+ return circuit_get_by_circid_channel_impl(circ_id, chan, &found) != NULL
+ || found;
}
/** Return the circuit that a given edge connection is using. */
@@ -1585,7 +1652,7 @@ assert_circuit_ok(const circuit_t *c)
/* We use the _impl variant here to make sure we don't fail on marked
* circuits, which would not be returned by the regular function. */
circuit_t *c2 = circuit_get_by_circid_channel_impl(c->n_circ_id,
- c->n_chan);
+ c->n_chan, NULL);
tor_assert(c == c2);
}
}
@@ -1593,7 +1660,7 @@ assert_circuit_ok(const circuit_t *c)
if (or_circ->p_circ_id) {
/* ibid */
circuit_t *c2 = circuit_get_by_circid_channel_impl(or_circ->p_circ_id,
- or_circ->p_chan);
+ or_circ->p_chan, NULL);
tor_assert(c == c2);
}
}
diff --git a/src/or/circuitlist.h b/src/or/circuitlist.h
index d67f80b..434d2a8 100644
--- a/src/or/circuitlist.h
+++ b/src/or/circuitlist.h
@@ -23,6 +23,8 @@ void circuit_set_p_circid_chan(or_circuit_t *circ, circid_t id,
channel_t *chan);
void circuit_set_n_circid_chan(circuit_t *circ, circid_t id,
channel_t *chan);
+void channel_mark_circid_unusable(channel_t *chan, circid_t id);
+void channel_mark_circid_usable(channel_t *chan, circid_t id);
void circuit_set_state(circuit_t *circ, uint8_t state);
void circuit_close_all_marked(void);
int32_t circuit_initial_package_window(void);
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