commit bce6714f99df6fd00c90918ac0a7407bf1f764e3 Author: Mike Perry mikeperry-git@fscked.org Date: Wed Jan 30 21:27:38 2013 -0400
Refactor code that rolls back the use state
Also document it better.
Mention this refactoring in the comments for the path state machine. --- src/or/circuitbuild.c | 25 +++++++++++++++++++++++++ src/or/circuitbuild.h | 1 + src/or/connection_edge.c | 25 +++++++------------------ src/or/or.h | 3 ++- 4 files changed, 35 insertions(+), 19 deletions(-)
diff --git a/src/or/circuitbuild.c b/src/or/circuitbuild.c index 2a3c40c..545184b 100644 --- a/src/or/circuitbuild.c +++ b/src/or/circuitbuild.c @@ -1678,6 +1678,31 @@ pathbias_mark_use_success(origin_circuit_t *circ) }
/** + * If a stream ever detatches from a circuit in a retriable way, + * we need to mark this circuit as still needing either another + * successful stream, or in need of a probe. + * + * An adversary could let the first stream request succeed (ie the + * resolve), but then tag and timeout the remainder (via cell + * dropping), forcing them on new circuits. + * + * Rolling back the state will cause us to probe such circuits, which + * should lead to probe failures in the event of such tagging due to + * either unrecognized cells coming in while we wait for the probe, + * or the cipher state getting out of sync in the case of dropped cells. + */ +void +pathbias_mark_use_rollback(origin_circuit_t *circ) +{ + if (circ->path_state == PATH_STATE_USE_SUCCEEDED) { + log_info(LD_CIRC, + "Rolling back pathbias use state to 'attempted' for detached " + "circuit %d", circ->global_identifier); + circ->path_state = PATH_STATE_USE_ATTEMPTED; + } +} + +/** * Actually count a circuit success towards a guard's usage counters * if the path state is appropriate. */ diff --git a/src/or/circuitbuild.h b/src/or/circuitbuild.h index d03a7c5..3ca8d15 100644 --- a/src/or/circuitbuild.h +++ b/src/or/circuitbuild.h @@ -65,6 +65,7 @@ int pathbias_check_close(origin_circuit_t *circ, int reason); int pathbias_check_probe_response(circuit_t *circ, const cell_t *cell); void pathbias_count_use_attempt(origin_circuit_t *circ); void pathbias_mark_use_success(origin_circuit_t *circ); +void pathbias_mark_use_rollback(origin_circuit_t *circ);
#endif
diff --git a/src/or/connection_edge.c b/src/or/connection_edge.c index 9e2c15d..b4fa3e6 100644 --- a/src/or/connection_edge.c +++ b/src/or/connection_edge.c @@ -637,21 +637,15 @@ connection_ap_expire_beginning(void) } if (circ->purpose == CIRCUIT_PURPOSE_C_REND_JOINED) { if (seconds_idle >= options->SocksTimeout) { - /* Path bias: We need to probe the circuit to ensure validity. - * Roll its state back if it succeeded so that we do so upon close. */ - if (TO_ORIGIN_CIRCUIT(circ)->path_state == PATH_STATE_USE_SUCCEEDED) { - log_info(LD_CIRC, - "Rolling back pathbias use state to 'attempted' for timed " - "out rend circ %d", - TO_ORIGIN_CIRCUIT(circ)->global_identifier); - TO_ORIGIN_CIRCUIT(circ)->path_state = PATH_STATE_USE_ATTEMPTED; - } - log_fn(severity, LD_REND, "Rend stream is %d seconds late. Giving up on address" " '%s.onion'.", seconds_idle, safe_str_client(entry_conn->socks_request->address)); + /* Roll back path bias use state so that we probe the circuit + * if nothing else succeeds on it */ + pathbias_mark_use_rollback(TO_ORIGIN_CIRCUIT(circ)); + connection_edge_end(conn, END_STREAM_REASON_TIMEOUT); connection_mark_unattached_ap(entry_conn, END_STREAM_REASON_TIMEOUT); } @@ -816,14 +810,9 @@ connection_ap_detach_retriable(entry_connection_t *conn, control_event_stream_status(conn, STREAM_EVENT_FAILED_RETRIABLE, reason); ENTRY_TO_CONN(conn)->timestamp_lastread = time(NULL);
- /* Path bias: We need to probe the circuit to ensure validity. - * Roll its state back if it succeeded so that we do so upon close. */ - if (circ->path_state == PATH_STATE_USE_SUCCEEDED) { - log_info(LD_CIRC, - "Rolling back pathbias use state to 'attempted' for detached " - "circuit %d", circ->global_identifier); - circ->path_state = PATH_STATE_USE_ATTEMPTED; - } + /* Roll back path bias use state so that we probe the circuit + * if nothing else succeeds on it */ + pathbias_mark_use_rollback(circ);
if (conn->pending_optimistic_data) { generic_buffer_set_to_copy(&conn->sending_optimistic_data, diff --git a/src/or/or.h b/src/or/or.h index e5fc06a..11158ff 100644 --- a/src/or/or.h +++ b/src/or/or.h @@ -2862,7 +2862,8 @@ typedef enum { * this circuit? * * If any streams detatch/fail from this circuit, the code transitions - * the circuit back to PATH_STATE_USE_ATTEMPTED to ensure we probe. + * the circuit back to PATH_STATE_USE_ATTEMPTED to ensure we probe. See + * pathbias_mark_use_rollback() for that. */ PATH_STATE_USE_SUCCEEDED = 4,