Merge remote-tracking branch 'public/bug9841_025'

6 files changed, 275 insertions, 39 deletions

diff --git a/changes/bug9841 b/changes/bug9841
new file mode 100644
index 000000000..8b40dda0c
--- /dev/null
+++ b/changes/bug9841
@@ -0,0 +1,7 @@
+  o Minor features (performance):
+
+    - Faster server-side lookups of rendezvous and introduction point
+      circuits by using hashtables instead of linear searches over all
+      the circuits. These functions previously accounted between 3 and
+      7% of CPU usage on some busy relays.
+
diff --git a/src/or/circuitlist.c b/src/or/circuitlist.c
index b03b590aa..87270037c 100644
--- a/src/or/circuitlist.c
+++ b/src/or/circuitlist.c
@@ -32,6 +32,7 @@
 #include "rephist.h"
 #include "routerlist.h"
 #include "routerset.h"
+
 #include "ht.h"
 
 /********* START VARIABLES **********/
@@ -45,6 +46,9 @@ static smartlist_t *circuits_pending_chans = NULL;
 
 static void circuit_free_cpath_node(crypt_path_t *victim);
 static void cpath_ref_decref(crypt_path_reference_t *cpath_ref);
+//static void circuit_set_rend_token(or_circuit_t *circ, int is_rend_circ,
+//                                   const uint8_t *token);
+static void circuit_clear_rend_token(or_circuit_t *circ);
 
 /********* END VARIABLES ************/
 
@@ -756,6 +760,8 @@ circuit_free(circuit_t *circ)
     crypto_cipher_free(ocirc->n_crypto);
     crypto_digest_free(ocirc->n_digest);
 
+    circuit_clear_rend_token(ocirc);
+
     if (ocirc->rend_splice) {
       or_circuit_t *other = ocirc->rend_splice;
       tor_assert(other->base_.magic == OR_CIRCUIT_MAGIC);
@@ -1229,43 +1235,167 @@ circuit_get_next_by_pk_and_purpose(origin_circuit_t *start,
   return NULL;
 }
 
-/** Return the first OR circuit in the global list whose purpose is
- * <b>purpose</b>, and whose rend_token is the <b>len</b>-byte
- * <b>token</b>. */
+/** Map from rendezvous cookie to or_circuit_t */
+static digestmap_t *rend_cookie_map = NULL;
+
+/** Map from introduction point digest to or_circuit_t */
+static digestmap_t *intro_digest_map = NULL;
+
+/** Return the OR circuit whose purpose is <b>purpose</b>, and whose
+ * rend_token is the REND_TOKEN_LEN-byte <b>token</b>. If <b>is_rend_circ</b>,
+ * look for rendezvous point circuits; otherwise look for introduction point
+ * circuits. */
 static or_circuit_t *
-circuit_get_by_rend_token_and_purpose(uint8_t purpose, const char *token,
-                                      size_t len)
+circuit_get_by_rend_token_and_purpose(uint8_t purpose, int is_rend_circ,
+                                      const char *token)
 {
-  circuit_t *circ;
-  TOR_LIST_FOREACH(circ, &global_circuitlist, head) {
-    if (! circ->marked_for_close &&
-        circ->purpose == purpose &&
-        tor_memeq(TO_OR_CIRCUIT(circ)->rend_token, token, len))
-      return TO_OR_CIRCUIT(circ);
+  or_circuit_t *circ;
+  digestmap_t *map = is_rend_circ ? rend_cookie_map : intro_digest_map;
+
+  if (!map)
+    return NULL;
+
+  circ = digestmap_get(map, token);
+  if (!circ ||
+      circ->base_.purpose != purpose ||
+      circ->base_.marked_for_close)
+    return NULL;
+
+  if (!circ->rendinfo ||
+      ! bool_eq(circ->rendinfo->is_rend_circ, is_rend_circ) ||
+      tor_memneq(circ->rendinfo->rend_token, token, REND_TOKEN_LEN)) {
+    char *t = tor_strdup(hex_str(token, REND_TOKEN_LEN));
+    log_warn(LD_BUG, "Wanted a circuit with %s:%d, but lookup returned %s:%d",
+             safe_str(t), is_rend_circ,
+             safe_str(hex_str(circ->rendinfo->rend_token, REND_TOKEN_LEN)),
+             (int)circ->rendinfo->is_rend_circ);
+    tor_free(t);
+    return NULL;
   }
-  return NULL;
+
+  return circ;
+}
+
+/** Clear the rendezvous cookie or introduction point key digest that's
+ * configured on <b>circ</b>, if any, and remove it from any such maps. */
+static void
+circuit_clear_rend_token(or_circuit_t *circ)
+{
+  or_circuit_t *found_circ;
+  digestmap_t *map;
+
+  if (!circ || !circ->rendinfo)
+    return;
+
+  map = circ->rendinfo->is_rend_circ ? rend_cookie_map : intro_digest_map;
+
+  if (!map) {
+    log_warn(LD_BUG, "Tried to clear rend token on circuit, but found no map");
+    return;
+  }
+
+  found_circ = digestmap_get(map, circ->rendinfo->rend_token);
+  if (found_circ == circ) {
+    /* Great, this is the right one. */
+    digestmap_remove(map, circ->rendinfo->rend_token);
+  } else if (found_circ) {
+    log_warn(LD_BUG, "Tried to clear rend token on circuit, but "
+             "it was already replaced in the map.");
+  } else {
+    log_warn(LD_BUG, "Tried to clear rend token on circuit, but "
+             "it not in the map at all.");
+  }
+
+  tor_free(circ->rendinfo); /* Sets it to NULL too */
+}
+
+/** Set the rendezvous cookie (if is_rend_circ), or the introduction point
+ * digest (if ! is_rend_circ) of <b>circ</b> to the REND_TOKEN_LEN-byte value
+ * in <b>token</b>, and add it to the appropriate map.  If it previously had a
+ * token, clear it.  If another circuit previously had the same
+ * cookie/intro-digest, mark that circuit and remove it from the map. */
+static void
+circuit_set_rend_token(or_circuit_t *circ, int is_rend_circ,
+                       const uint8_t *token)
+{
+  digestmap_t **map_p, *map;
+  or_circuit_t *found_circ;
+
+  /* Find the right map, creating it as needed */
+  map_p = is_rend_circ ? &rend_cookie_map : &intro_digest_map;
+
+  if (!*map_p)
+    *map_p = digestmap_new();
+
+  map = *map_p;
+
+  /* If this circuit already has a token, we need to remove that. */
+  if (circ->rendinfo)
+    circuit_clear_rend_token(circ);
+
+  if (token == NULL) {
+    /* We were only trying to remove this token, not set a new one. */
+    return;
+  }
+
+  found_circ = digestmap_get(map, (const char *)token);
+  if (found_circ) {
+    tor_assert(found_circ != circ);
+    circuit_clear_rend_token(found_circ);
+    if (! found_circ->base_.marked_for_close) {
+      circuit_mark_for_close(TO_CIRCUIT(found_circ), END_CIRC_REASON_FINISHED);
+      if (is_rend_circ) {
+        log_fn(LOG_PROTOCOL_WARN, LD_REND,
+               "Duplicate rendezvous cookie (%s...) used on two circuits",
+               hex_str((const char*)token, 4)); /* only log first 4 chars */
+      }
+    }
+  }
+
+  /* Now set up the rendinfo */
+  circ->rendinfo = tor_malloc(sizeof(*circ->rendinfo));
+  memcpy(circ->rendinfo->rend_token, token, REND_TOKEN_LEN);
+  circ->rendinfo->is_rend_circ = is_rend_circ ? 1 : 0;
+
+  digestmap_set(map, (const char *)token, circ);
 }
 
 /** Return the circuit waiting for a rendezvous with the provided cookie.
  * Return NULL if no such circuit is found.
  */
 or_circuit_t *
-circuit_get_rendezvous(const char *cookie)
+circuit_get_rendezvous(const uint8_t *cookie)
 {
   return circuit_get_by_rend_token_and_purpose(
                                      CIRCUIT_PURPOSE_REND_POINT_WAITING,
-                                     cookie, REND_COOKIE_LEN);
+                                     1, (const char*)cookie);
 }
 
 /** Return the circuit waiting for intro cells of the given digest.
  * Return NULL if no such circuit is found.
  */
 or_circuit_t *
-circuit_get_intro_point(const char *digest)
+circuit_get_intro_point(const uint8_t *digest)
 {
   return circuit_get_by_rend_token_and_purpose(
-                                     CIRCUIT_PURPOSE_INTRO_POINT, digest,
-                                     DIGEST_LEN);
+                                     CIRCUIT_PURPOSE_INTRO_POINT, 0,
+                                     (const char *)digest);
+}
+
+/** Set the rendezvous cookie of <b>circ</b> to <b>cookie</b>.  If another
+ * circuit previously had that cookie, mark it. */
+void
+circuit_set_rendezvous_cookie(or_circuit_t *circ, const uint8_t *cookie)
+{
+  circuit_set_rend_token(circ, 1, cookie);
+}
+
+/** Set the intro point key digest of <b>circ</b> to <b>cookie</b>.  If another
+ * circuit previously had that intro point digest, mark it. */
+void
+circuit_set_intro_point_digest(or_circuit_t *circ, const uint8_t *digest)
+{
+  circuit_set_rend_token(circ, 0, digest);
 }
 
 /** Return a circuit that is open, is CIRCUIT_PURPOSE_C_GENERAL,
diff --git a/src/or/circuitlist.h b/src/or/circuitlist.h
index 54a7ef42f..2bbd20b83 100644
--- a/src/or/circuitlist.h
+++ b/src/or/circuitlist.h
@@ -46,8 +46,10 @@ origin_circuit_t *circuit_get_ready_rend_circ_by_rend_data(
   const rend_data_t *rend_data);
 origin_circuit_t *circuit_get_next_by_pk_and_purpose(origin_circuit_t *start,
                                          const char *digest, uint8_t purpose);
-or_circuit_t *circuit_get_rendezvous(const char *cookie);
-or_circuit_t *circuit_get_intro_point(const char *digest);
+or_circuit_t *circuit_get_rendezvous(const uint8_t *cookie);
+or_circuit_t *circuit_get_intro_point(const uint8_t *digest);
+void circuit_set_rendezvous_cookie(or_circuit_t *circ, const uint8_t *cookie);
+void circuit_set_intro_point_digest(or_circuit_t *circ, const uint8_t *digest);
 origin_circuit_t *circuit_find_to_cannibalize(uint8_t purpose,
                                               extend_info_t *info, int flags);
 void circuit_mark_all_unused_circs(void);
diff --git a/src/or/or.h b/src/or/or.h
index 1b35c1f99..e17b5816a 100644
--- a/src/or/or.h
+++ b/src/or/or.h
@@ -3174,20 +3174,8 @@ typedef struct or_circuit_t {
    * is not marked for close. */
   struct or_circuit_t *rend_splice;
 
-#if REND_COOKIE_LEN >= DIGEST_LEN
-#define REND_TOKEN_LEN REND_COOKIE_LEN
-#else
-#define REND_TOKEN_LEN DIGEST_LEN
-#endif
+  struct or_circuit_rendinfo_s *rendinfo;
 
-  /** A hash of location-hidden service's PK if purpose is INTRO_POINT, or a
-   * rendezvous cookie if purpose is REND_POINT_WAITING. Filled with zeroes
-   * otherwise.
-   * ???? move to a subtype or adjunct structure? Wastes 20 bytes. -NM
-   */
-  char rend_token[REND_TOKEN_LEN];
-
-  /* ???? move to a subtype or adjunct structure? Wastes 20 bytes -NM */
   /** Stores KH for the handshake. */
   char rend_circ_nonce[DIGEST_LEN];/* KH in tor-spec.txt */
 
@@ -3214,6 +3202,25 @@ typedef struct or_circuit_t {
   uint32_t max_middle_cells;
 } or_circuit_t;
 
+typedef struct or_circuit_rendinfo_s {
+
+#if REND_COOKIE_LEN != DIGEST_LEN
+#error "The REND_TOKEN_LEN macro assumes REND_COOKIE_LEN == DIGEST_LEN"
+#endif
+#define REND_TOKEN_LEN DIGEST_LEN
+
+  /** A hash of location-hidden service's PK if purpose is INTRO_POINT, or a
+   * rendezvous cookie if purpose is REND_POINT_WAITING. Filled with zeroes
+   * otherwise.
+   */
+  char rend_token[REND_TOKEN_LEN];
+
+  /** True if this is a rendezvous point circuit; false if this is an
+   * introduction point. */
+  unsigned is_rend_circ;
+
+} or_circuit_rendinfo_t;
+
 /** Convert a circuit subtype to a circuit_t. */
 #define TO_CIRCUIT(x)  (&((x)->base_))
 
diff --git a/src/or/rendmid.c b/src/or/rendmid.c
index c68f6da59..110381680 100644
--- a/src/or/rendmid.c
+++ b/src/or/rendmid.c
@@ -94,7 +94,7 @@ rend_mid_establish_intro(or_circuit_t *circ, const uint8_t *request,
 
   /* Close any other intro circuits with the same pk. */
   c = NULL;
-  while ((c = circuit_get_intro_point(pk_digest))) {
+  while ((c = circuit_get_intro_point((const uint8_t *)pk_digest))) {
     log_info(LD_REND, "Replacing old circuit for service %s",
              safe_str(serviceid));
     circuit_mark_for_close(TO_CIRCUIT(c), END_CIRC_REASON_FINISHED);
@@ -111,7 +111,7 @@ rend_mid_establish_intro(or_circuit_t *circ, const uint8_t *request,
 
   /* Now, set up this circuit. */
   circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_INTRO_POINT);
-  memcpy(circ->rend_token, pk_digest, DIGEST_LEN);
+  circuit_set_intro_point_digest(circ, (uint8_t *)pk_digest);
 
   log_info(LD_REND,
            "Established introduction point on circuit %u for service %s",
@@ -165,7 +165,7 @@ rend_mid_introduce(or_circuit_t *circ, const uint8_t *request,
                 (char*)request, REND_SERVICE_ID_LEN);
 
   /* The first 20 bytes are all we look at: they have a hash of Bob's PK. */
-  intro_circ = circuit_get_intro_point((char*)request);
+  intro_circ = circuit_get_intro_point((const uint8_t*)request);
   if (!intro_circ) {
     log_info(LD_REND,
              "No intro circ found for INTRODUCE1 cell (%s) from circuit %u; "
@@ -236,7 +236,7 @@ rend_mid_establish_rendezvous(or_circuit_t *circ, const uint8_t *request,
     goto err;
   }
 
-  if (circuit_get_rendezvous((char*)request)) {
+  if (circuit_get_rendezvous(request)) {
     log_warn(LD_PROTOCOL,
              "Duplicate rendezvous cookie in ESTABLISH_RENDEZVOUS.");
     goto err;
@@ -252,7 +252,7 @@ rend_mid_establish_rendezvous(or_circuit_t *circ, const uint8_t *request,
   }
 
   circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_REND_POINT_WAITING);
-  memcpy(circ->rend_token, request, REND_COOKIE_LEN);
+  circuit_set_rendezvous_cookie(circ, request);
 
   base16_encode(hexid,9,(char*)request,4);
 
@@ -300,7 +300,7 @@ rend_mid_rendezvous(or_circuit_t *circ, const uint8_t *request,
            "Got request for rendezvous from circuit %u to cookie %s.",
            (unsigned)circ->p_circ_id, hexid);
 
-  rend_circ = circuit_get_rendezvous((char*)request);
+  rend_circ = circuit_get_rendezvous(request);
   if (!rend_circ) {
     log_fn(LOG_PROTOCOL_WARN, LD_PROTOCOL,
          "Rejecting RENDEZVOUS1 cell with unrecognized rendezvous cookie %s.",
@@ -328,7 +328,7 @@ rend_mid_rendezvous(or_circuit_t *circ, const uint8_t *request,
   circuit_change_purpose(TO_CIRCUIT(circ), CIRCUIT_PURPOSE_REND_ESTABLISHED);
   circuit_change_purpose(TO_CIRCUIT(rend_circ),
                          CIRCUIT_PURPOSE_REND_ESTABLISHED);
-  memset(circ->rend_token, 0, REND_COOKIE_LEN);
+  circuit_set_rendezvous_cookie(circ, NULL);
 
   rend_circ->rend_splice = circ;
   circ->rend_splice = rend_circ;
diff --git a/src/test/test_circuitlist.c b/src/test/test_circuitlist.c
index 54aa51d3c..54c0c03ca 100644
--- a/src/test/test_circuitlist.c
+++ b/src/test/test_circuitlist.c
@@ -161,8 +161,98 @@ test_clist_maps(void *arg)
   UNMOCK(circuitmux_detach_circuit);
 }
 
+static void
+test_rend_token_maps(void *arg)
+{
+  or_circuit_t *c1, *c2, *c3, *c4;
+  const uint8_t tok1[REND_TOKEN_LEN] = "The cat can't tell y";
+  const uint8_t tok2[REND_TOKEN_LEN] = "ou its name, and it ";
+  const uint8_t tok3[REND_TOKEN_LEN] = "doesn't really care.";
+  /* -- Adapted from a quote by Fredrik Lundh. */
+
+  (void)arg;
+  (void)tok1; //xxxx
+  c1 = or_circuit_new(0, NULL);
+  c2 = or_circuit_new(0, NULL);
+  c3 = or_circuit_new(0, NULL);
+  c4 = or_circuit_new(0, NULL);
+
+  tt_int_op(strlen((char*)tok1), ==, REND_TOKEN_LEN);
+
+  /* No maps; nothing there. */
+  tt_ptr_op(NULL, ==, circuit_get_rendezvous(tok1));
+  tt_ptr_op(NULL, ==, circuit_get_intro_point(tok1));
+
+  circuit_set_rendezvous_cookie(c1, tok1);
+  circuit_set_intro_point_digest(c2, tok2);
+
+  tt_ptr_op(NULL, ==, circuit_get_rendezvous(tok3));
+  tt_ptr_op(NULL, ==, circuit_get_intro_point(tok3));
+  tt_ptr_op(NULL, ==, circuit_get_rendezvous(tok2));
+  tt_ptr_op(NULL, ==, circuit_get_intro_point(tok1));
+
+  /* Without purpose set, we don't get the circuits */
+  tt_ptr_op(NULL, ==, circuit_get_rendezvous(tok1));
+  tt_ptr_op(NULL, ==, circuit_get_intro_point(tok2));
+
+  c1->base_.purpose = CIRCUIT_PURPOSE_REND_POINT_WAITING;
+  c2->base_.purpose = CIRCUIT_PURPOSE_INTRO_POINT;
+
+  /* Okay, make sure they show up now. */
+  tt_ptr_op(c1, ==, circuit_get_rendezvous(tok1));
+  tt_ptr_op(c2, ==, circuit_get_intro_point(tok2));
+
+  /* Two items at the same place with the same token. */
+  c3->base_.purpose = CIRCUIT_PURPOSE_REND_POINT_WAITING;
+  circuit_set_rendezvous_cookie(c3, tok2);
+  tt_ptr_op(c2, ==, circuit_get_intro_point(tok2));
+  tt_ptr_op(c3, ==, circuit_get_rendezvous(tok2));
+
+  /* Marking a circuit makes it not get returned any more */
+  circuit_mark_for_close(TO_CIRCUIT(c1), END_CIRC_REASON_FINISHED);
+  tt_ptr_op(NULL, ==, circuit_get_rendezvous(tok1));
+  circuit_free(TO_CIRCUIT(c1));
+  c1 = NULL;
+
+  /* Freeing a circuit makes it not get returned any more. */
+  circuit_free(TO_CIRCUIT(c2));
+  c2 = NULL;
+  tt_ptr_op(NULL, ==, circuit_get_intro_point(tok2));
+
+  /* c3 -- are you still there? */
+  tt_ptr_op(c3, ==, circuit_get_rendezvous(tok2));
+  /* Change its cookie.  This never happens in Tor per se, but hey. */
+  c3->base_.purpose = CIRCUIT_PURPOSE_INTRO_POINT;
+  circuit_set_intro_point_digest(c3, tok3);
+
+  tt_ptr_op(NULL, ==, circuit_get_rendezvous(tok2));
+  tt_ptr_op(c3, ==, circuit_get_intro_point(tok3));
+
+  /* Now replace c3 with c4. */
+  c4->base_.purpose = CIRCUIT_PURPOSE_INTRO_POINT;
+  circuit_set_intro_point_digest(c4, tok3);
+
+  tt_ptr_op(c4, ==, circuit_get_intro_point(tok3));
+
+  tt_ptr_op(c3->rendinfo, ==, NULL);
+  tt_ptr_op(c4->rendinfo, !=, NULL);
+  test_mem_op(c4->rendinfo, ==, tok3, REND_TOKEN_LEN);
+
+  /* Now clear c4's cookie. */
+  circuit_set_intro_point_digest(c4, NULL);
+  tt_ptr_op(c4->rendinfo, ==, NULL);
+  tt_ptr_op(NULL, ==, circuit_get_intro_point(tok3));
+
+ done:
+  circuit_free(TO_CIRCUIT(c1));
+  circuit_free(TO_CIRCUIT(c2));
+  circuit_free(TO_CIRCUIT(c3));
+  circuit_free(TO_CIRCUIT(c4));
+}
+
 struct testcase_t circuitlist_tests[] = {
   { "maps", test_clist_maps, TT_FORK, NULL, NULL },
+  { "rend_token_maps", test_rend_token_maps, TT_FORK, NULL, NULL },
   END_OF_TESTCASES
 };