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Refactor code that rolls back the use state

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Also document it better.

Mention this refactoring in the comments for the path state machine.
This commit is contained in:
Mike Perry 2013-01-30 21:27:38 -04:00 committed by Nick Mathewson
parent 3a63e5ef42
commit bce6714f99
4 changed files with 35 additions and 19 deletions
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25
src/or/circuitbuild.c
View File

@ -1677,6 +1677,31 @@ pathbias_mark_use_success(origin_circuit_t *circ)
return;
}
/**
* 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.

1
src/or/circuitbuild.h
View File

@ -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

25
src/or/connection_edge.c
View File

@ -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,

3
src/or/or.h
View File

@ -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,