[tor-commits] [tor/master] prop224: Use the intro point state cache
nickm at torproject.org
nickm at torproject.org
Thu Aug 24 19:13:52 UTC 2017
commit 14b858c4ced594ee5130a685ac4b143bf66da04a
Author: David Goulet <dgoulet at torproject.org>
Date: Thu Jul 27 17:06:42 2017 -0400
prop224: Use the intro point state cache
This commit makes the client use the intro point state cache. It notes down
when we get a NACK from the intro point and then uses that cache to decide if
it should either close the circuits or re-extend to a new intro point.
This also introduces a very useful function that checks if an intro point is
usable that is query the state cache and checks a series of requirement.
Signed-off-by: David Goulet <dgoulet at torproject.org>
---
src/or/hs_client.c | 122 ++++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 117 insertions(+), 5 deletions(-)
diff --git a/src/or/hs_client.c b/src/or/hs_client.c
index 68b33b196..06cbcc409 100644
--- a/src/or/hs_client.c
+++ b/src/or/hs_client.c
@@ -419,6 +419,51 @@ desc_intro_point_to_extend_info(const hs_desc_intro_point_t *ip)
return ei;
}
+/* Return true iff the intro point ip for the service service_pk is usable.
+ * This function checks if the intro point is in the client intro state cache
+ * and checks at the failures. It is considered usable if:
+ * - No error happened (INTRO_POINT_FAILURE_GENERIC)
+ * - It is not flagged as timed out (INTRO_POINT_FAILURE_TIMEOUT)
+ * - The unreachable count is lower than
+ * MAX_INTRO_POINT_REACHABILITY_FAILURES (INTRO_POINT_FAILURE_UNREACHABLE)
+ */
+static int
+intro_point_is_usable(const ed25519_public_key_t *service_pk,
+ const hs_desc_intro_point_t *ip)
+{
+ const hs_cache_intro_state_t *state;
+
+ tor_assert(service_pk);
+ tor_assert(ip);
+
+ state = hs_cache_client_intro_state_find(service_pk,
+ &ip->auth_key_cert->signed_key);
+ if (state == NULL) {
+ /* This means we've never encountered any problem thus usable. */
+ goto usable;
+ }
+ if (state->error) {
+ log_info(LD_REND, "Intro point with auth key %s had an error. Not usable",
+ safe_str_client(ed25519_fmt(&ip->auth_key_cert->signed_key)));
+ goto not_usable;
+ }
+ if (state->timed_out) {
+ log_info(LD_REND, "Intro point with auth key %s timed out. Not usable",
+ safe_str_client(ed25519_fmt(&ip->auth_key_cert->signed_key)));
+ goto not_usable;
+ }
+ if (state->unreachable_count >= MAX_INTRO_POINT_REACHABILITY_FAILURES) {
+ log_info(LD_REND, "Intro point with auth key %s unreachable. Not usable",
+ safe_str_client(ed25519_fmt(&ip->auth_key_cert->signed_key)));
+ goto not_usable;
+ }
+
+ usable:
+ return 1;
+ not_usable:
+ return 0;
+}
+
/* Using a descriptor desc, return a newly allocated extend_info_t object of a
* randomly picked introduction point from its list. Return NULL if none are
* usable. */
@@ -454,6 +499,12 @@ client_get_random_intro(const ed25519_public_key_t *service_pk)
ip = smartlist_get(usable_ips, idx);
smartlist_del(usable_ips, idx);
+ /* We need to make sure we have a usable intro points which is in a good
+ * state in our cache. */
+ if (!intro_point_is_usable(service_pk, ip)) {
+ continue;
+ }
+
/* Generate an extend info object from the intro point object. */
ei = desc_intro_point_to_extend_info(ip);
if (ei == NULL) {
@@ -470,8 +521,6 @@ client_get_random_intro(const ed25519_public_key_t *service_pk)
ei_excluded = ei;
continue;
}
- /* XXX: Intro point can time out or just be unsuable, we need to keep
- * track of this and check against such cache. */
/* Good pick! Let's go with this. */
goto end;
@@ -493,6 +542,62 @@ client_get_random_intro(const ed25519_public_key_t *service_pk)
return ei;
}
+/* For this introduction circuit, we'll look at if we have any usable
+ * introduction point left for this service. If so, we'll use the circuit to
+ * re-extend to a new intro point. Else, we'll close the circuit and its
+ * corresponding rendezvous circuit. Return 0 if we are re-extending else -1
+ * if we are closing the circuits.
+ *
+ * This is called when getting an INTRODUCE_ACK cell with a NACK. */
+static int
+close_or_reextend_intro_circ(origin_circuit_t *intro_circ)
+{
+ int ret = -1;
+ const hs_descriptor_t *desc;
+ origin_circuit_t *rend_circ;
+
+ tor_assert(intro_circ);
+
+ desc = hs_cache_lookup_as_client(&intro_circ->hs_ident->identity_pk);
+ if (BUG(desc == NULL)) {
+ /* We can't continue without a descriptor. */
+ goto close;
+ }
+ /* We still have the descriptor, great! Let's try to see if we can
+ * re-extend by looking up if there are any usable intro points. */
+ if (!hs_client_any_intro_points_usable(desc)) {
+ goto close;
+ }
+ /* Try to re-extend now. */
+ if (hs_client_reextend_intro_circuit(intro_circ) < 0) {
+ goto close;
+ }
+ /* Success on re-extending. Don't return an error. */
+ ret = 0;
+ goto end;
+
+ close:
+ /* Change the intro circuit purpose before so we don't report an intro point
+ * failure again triggering an extra descriptor fetch. The circuit can
+ * already be closed on failure to re-extend. */
+ if (!TO_CIRCUIT(intro_circ)->marked_for_close) {
+ circuit_change_purpose(TO_CIRCUIT(intro_circ),
+ CIRCUIT_PURPOSE_C_INTRODUCE_ACKED);
+ circuit_mark_for_close(TO_CIRCUIT(intro_circ), END_CIRC_REASON_FINISHED);
+ }
+ /* Close the related rendezvous circuit. */
+ rend_circ = hs_circuitmap_get_rend_circ_client_side(
+ intro_circ->hs_ident->rendezvous_cookie);
+ /* The rendezvous circuit might have collapsed while the INTRODUCE_ACK was
+ * inflight so we can't expect one every time. */
+ if (rend_circ) {
+ circuit_mark_for_close(TO_CIRCUIT(rend_circ), END_CIRC_REASON_FINISHED);
+ }
+
+ end:
+ return ret;
+}
+
/* Called when we get an INTRODUCE_ACK success status code. Do the appropriate
* actions for the rendezvous point and finally close intro_circ. */
static void
@@ -545,8 +650,11 @@ handle_introduce_ack_bad(origin_circuit_t *circ, int status)
/* It's a NAK. The introduction point didn't relay our request. */
circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_C_INTRODUCING);
- /* XXX: Report this failure for the intro point failure cache. Depending on
- * how many times we've tried this intro point, close it or reextend. */
+ /* Note down this failure in the intro point failure cache. Depending on how
+ * many times we've tried this intro point, close it or reextend. */
+ hs_cache_client_intro_state_note(&circ->hs_ident->identity_pk,
+ &circ->hs_ident->intro_auth_pk,
+ INTRO_POINT_FAILURE_GENERIC);
}
/* Called when we get an INTRODUCE_ACK on the intro circuit circ. The encoded
@@ -570,11 +678,14 @@ handle_introduce_ack(origin_circuit_t *circ, const uint8_t *payload,
case HS_CELL_INTRO_ACK_SUCCESS:
ret = 0;
handle_introduce_ack_success(circ);
- break;
+ goto end;
case HS_CELL_INTRO_ACK_FAILURE:
case HS_CELL_INTRO_ACK_BADFMT:
case HS_CELL_INTRO_ACK_NORELAY:
handle_introduce_ack_bad(circ, status);
+ /* We are going to see if we have to close the circuits (IP and RP) or we
+ * can re-extend to a new intro point. */
+ ret = close_or_reextend_intro_circ(circ);
break;
default:
log_info(LD_PROTOCOL, "Unknown INTRODUCE_ACK status code %u from %s",
@@ -583,6 +694,7 @@ handle_introduce_ack(origin_circuit_t *circ, const uint8_t *payload,
break;
}
+ end:
return ret;
}
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