diff options
Diffstat (limited to 'src/or/rendmid.c')
| -rw-r--r-- | src/or/rendmid.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/src/or/rendmid.c b/src/or/rendmid.c index 9f6ff86c47..2451acb514 100644 --- a/src/or/rendmid.c +++ b/src/or/rendmid.c @@ -149,6 +149,20 @@ rend_mid_introduce(or_circuit_t *circ, const uint8_t *request, goto err; } + /* We have already done an introduction on this circuit but we just + received a request for another one. We block it since this might + be an attempt to DoS a hidden service (#15515). */ + if (circ->already_received_introduce1) { + log_fn(LOG_PROTOCOL_WARN, LD_REND, + "Blocking multiple introductions on the same circuit. " + "Someone might be trying to attack a hidden service through " + "this relay."); + circuit_mark_for_close(TO_CIRCUIT(circ), END_CIRC_REASON_TORPROTOCOL); + return -1; + } + + circ->already_received_introduce1 = 1; + /* We could change this to MAX_HEX_NICKNAME_LEN now that 0.0.9.x is * obsolete; however, there isn't much reason to do so, and we're going * to revise this protocol anyway. |