diff options
Diffstat (limited to 'src/or/circuitbuild.c')
| -rw-r--r-- | src/or/circuitbuild.c | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/src/or/circuitbuild.c b/src/or/circuitbuild.c index 7b852ff5c6..8d6aad605c 100644 --- a/src/or/circuitbuild.c +++ b/src/or/circuitbuild.c @@ -102,6 +102,12 @@ channel_connect_for_circuit(const tor_addr_t *addr, uint16_t port, static circid_t get_unique_circ_id_by_chan(channel_t *chan) { +/* This number is chosen somewhat arbitrarily; see comment below for more + * info. When the space is 80% full, it gives a one-in-a-million failure + * chance; when the space is 90% full, it gives a one-in-850 chance; and when + * the space is 95% full, it gives a one-in-26 failure chance. That seems + * okay, though you could make a case IMO for anything between N=32 and + * N=256. */ #define MAX_CIRCID_ATTEMPTS 64 circid_t test_circ_id; @@ -137,19 +143,20 @@ get_unique_circ_id_by_chan(channel_t *chan) * whole circuit ID space every time we extend a circuit, which is * not so great either. */ - if (! chan->warned_circ_ids_exhausted) { - chan->warned_circ_ids_exhausted = 1; - log_warn(LD_CIRC,"No unused circIDs found on channel %s wide " + log_fn_ratelim(&chan->last_warned_circ_ids_exhausted, LOG_WARN, + LD_CIRC,"No unused circIDs found on channel %s wide " "circID support, with %u inbound and %u outbound circuits. " "Failing a circuit.", chan->wide_circ_ids ? "with" : "without", chan->num_p_circuits, chan->num_n_circuits); - } return 0; } - crypto_rand((char*) &test_circ_id, sizeof(test_circ_id)); - test_circ_id &= mask; + do { + crypto_rand((char*) &test_circ_id, sizeof(test_circ_id)); + test_circ_id &= mask; + } while (test_circ_id == 0); + test_circ_id |= high_bit; } while (circuit_id_in_use_on_channel(test_circ_id, chan)); return test_circ_id; |