Introduce cache for outdated microdesc dirservers.

We gonna use this cache to avoid dirservers without outdated md info.

5 files changed, 138 insertions, 15 deletions

diff --git a/src/or/directory.c b/src/or/directory.c
index 9494cf02ba..129309ae47 100644
--- a/src/or/directory.c
+++ b/src/or/directory.c
@@ -117,7 +117,8 @@ static void dir_routerdesc_download_failed(smartlist_t *failed,
                                            int was_extrainfo,
                                            int was_descriptor_digests);
 static void dir_microdesc_download_failed(smartlist_t *failed,
-                                          int status_code);
+                                          int status_code,
+                                          const char *dir_id);
 static int client_likes_consensus(const struct consensus_cache_entry_t *ent,
                                   const char *want_url);
 
@@ -2178,8 +2179,6 @@ static int handle_response_fetch_detached_signatures(dir_connection_t *,
                                              const response_handler_args_t *);
 static int handle_response_fetch_desc(dir_connection_t *,
                                              const response_handler_args_t *);
-static int handle_response_fetch_microdesc(dir_connection_t *,
-                                           const response_handler_args_t *);
 static int handle_response_upload_dir(dir_connection_t *,
                                       const response_handler_args_t *);
 static int handle_response_upload_vote(dir_connection_t *,
@@ -2839,7 +2838,7 @@ handle_response_fetch_desc(dir_connection_t *conn,
  * Handler function: processes a response to a request for a group of
  * microdescriptors
  **/
-static int
+STATIC int
 handle_response_fetch_microdesc(dir_connection_t *conn,
                                 const response_handler_args_t *args)
 {
@@ -2856,6 +2855,7 @@ handle_response_fetch_microdesc(dir_connection_t *conn,
            conn->base_.port);
   tor_assert(conn->requested_resource &&
              !strcmpstart(conn->requested_resource, "d/"));
+  tor_assert_nonfatal(!tor_mem_is_zero(conn->identity_digest, DIGEST_LEN));
   which = smartlist_new();
   dir_split_resource_into_fingerprints(conn->requested_resource+2,
                                        which, NULL,
@@ -2866,7 +2866,7 @@ handle_response_fetch_microdesc(dir_connection_t *conn,
              "soon.",
              status_code, escaped(reason), conn->base_.address,
              (int)conn->base_.port, conn->requested_resource);
-    dir_microdesc_download_failed(which, status_code);
+    dir_microdesc_download_failed(which, status_code, conn->identity_digest);
     SMARTLIST_FOREACH(which, char *, cp, tor_free(cp));
     smartlist_free(which);
     return 0;
@@ -2878,7 +2878,7 @@ handle_response_fetch_microdesc(dir_connection_t *conn,
                                   now, which);
     if (smartlist_len(which)) {
       /* Mark remaining ones as failed. */
-      dir_microdesc_download_failed(which, status_code);
+      dir_microdesc_download_failed(which, status_code, conn->identity_digest);
     }
     if (mds && smartlist_len(mds)) {
       control_event_bootstrap(BOOTSTRAP_STATUS_LOADING_DESCRIPTORS,
@@ -5546,13 +5546,14 @@ dir_routerdesc_download_failed(smartlist_t *failed, int status_code,
    * every 10 or 60 seconds (FOO_DESCRIPTOR_RETRY_INTERVAL) in main.c. */
 }
 
-/** Called when a connection to download microdescriptors has failed in whole
- * or in part. <b>failed</b> is a list of every microdesc digest we didn't
- * get. <b>status_code</b> is the http status code we received. Reschedule the
- * microdesc downloads as appropriate. */
+/** Called when a connection to download microdescriptors from relay with
+ * <b>dir_id</b> has failed in whole or in part. <b>failed</b> is a list
+ * of every microdesc digest we didn't get. <b>status_code</b> is the http
+ * status code we received. Reschedule the microdesc downloads as
+ * appropriate. */
 static void
 dir_microdesc_download_failed(smartlist_t *failed,
-                              int status_code)
+                              int status_code, const char *dir_id)
 {
   networkstatus_t *consensus
     = networkstatus_get_latest_consensus_by_flavor(FLAV_MICRODESC);
@@ -5563,17 +5564,26 @@ dir_microdesc_download_failed(smartlist_t *failed,
 
   if (! consensus)
     return;
+
+  /* We failed to fetch a microdescriptor from 'dir_id', note it down
+   * so that we don't try the same relay next time... */
+  microdesc_note_outdated_dirserver(dir_id);
+
   SMARTLIST_FOREACH_BEGIN(failed, const char *, d) {
     rs = router_get_mutable_consensus_status_by_descriptor_digest(consensus,d);
     if (!rs)
       continue;
     dls = &rs->dl_status;
     if (dls->n_download_failures >=
-        get_options()->TestingMicrodescMaxDownloadTries)
+        get_options()->TestingMicrodescMaxDownloadTries) {
       continue;
-    {
+    }
+
+    { /* Increment the failure count for this md fetch */
       char buf[BASE64_DIGEST256_LEN+1];
       digest256_to_base64(buf, d);
+      log_info(LD_DIR, "Failed to download md %s from %s",
+               buf, hex_str(dir_id, DIGEST_LEN));
       download_status_increment_failure(dls, status_code, buf,
                                         server, now);
     }
diff --git a/src/or/directory.h b/src/or/directory.h
index 14d5ae9ef4..571c30a0fc 100644
--- a/src/or/directory.h
+++ b/src/or/directory.h
@@ -166,7 +166,12 @@ STATIC char *accept_encoding_header(void);
 STATIC int allowed_anonymous_connection_compression_method(compress_method_t);
 STATIC void warn_disallowed_anonymous_compression_method(compress_method_t);
 
-#endif
+struct response_handler_args_t;
+
+STATIC int handle_response_fetch_microdesc(dir_connection_t *conn,
+                                 const struct response_handler_args_t *args);
+
+#endif /* defined(DIRECTORY_PRIVATE) */
 
 #ifdef TOR_UNIT_TESTS
 /* Used only by test_dir.c */
diff --git a/src/or/microdesc.c b/src/or/microdesc.c
index a4e6b409c4..32242d0054 100644
--- a/src/or/microdesc.c
+++ b/src/or/microdesc.c
@@ -74,6 +74,102 @@ HT_GENERATE2(microdesc_map, microdesc_t, node,
              microdesc_hash_, microdesc_eq_, 0.6,
              tor_reallocarray_, tor_free_)
 
+/************************* md fetch fail cache *****************************/
+
+/* If we end up with too many outdated dirservers, something probably went
+ * wrong so clean up the list. */
+#define TOO_MANY_OUTDATED_DIRSERVERS 30
+
+/** List of dirservers with outdated microdesc information. The smartlist is
+ *  filled with the hex digests of outdated dirservers. */
+static smartlist_t *outdated_dirserver_list = NULL;
+
+/** Note that we failed to fetch a microdescriptor from the relay with
+ *  <b>relay_digest</b> (of size DIGEST_LEN). */
+void
+microdesc_note_outdated_dirserver(const char *relay_digest)
+{
+  char relay_hexdigest[HEX_DIGEST_LEN+1];
+
+  /* Don't register outdated dirservers if we don't have a live consensus,
+   * since we might be trying to fetch microdescriptors that are not even
+   * currently active. */
+  if (!networkstatus_get_live_consensus(approx_time())) {
+    return;
+  }
+
+  if (!outdated_dirserver_list) {
+    outdated_dirserver_list = smartlist_new();
+  }
+
+  tor_assert(outdated_dirserver_list);
+
+  /* If the list grows too big, clean it up */
+  if (BUG(smartlist_len(outdated_dirserver_list) >
+          TOO_MANY_OUTDATED_DIRSERVERS)) {
+    microdesc_reset_outdated_dirservers_list();
+  }
+
+  /* Turn the binary relay digest to a hex since smartlists have better support
+   * for strings than digests. */
+  base16_encode(relay_hexdigest,sizeof(relay_hexdigest),
+                relay_digest, DIGEST_LEN);
+
+  /* Make sure we don't add a dirauth as an outdated dirserver */
+  if (router_get_trusteddirserver_by_digest(relay_digest)) {
+    log_info(LD_GENERAL, "Auth %s gave us outdated dirinfo.", relay_hexdigest);
+    return;
+  }
+
+  /* Don't double-add outdated dirservers */
+  if (smartlist_contains_string(outdated_dirserver_list, relay_hexdigest)) {
+    return;
+  }
+
+  /* Add it to the list of outdated dirservers */
+  smartlist_add_strdup(outdated_dirserver_list, relay_hexdigest);
+
+  log_info(LD_GENERAL, "Noted %s as outdated md dirserver", relay_hexdigest);
+}
+
+/** Return True if the relay with <b>relay_digest</b> (size DIGEST_LEN) is an
+ *  outdated dirserver */
+int
+microdesc_relay_is_outdated_dirserver(const char *relay_digest)
+{
+  char relay_hexdigest[HEX_DIGEST_LEN+1];
+
+  if (!outdated_dirserver_list) {
+    return 0;
+  }
+
+  /* Convert identity digest to hex digest */
+  base16_encode(relay_hexdigest, sizeof(relay_hexdigest),
+                relay_digest, DIGEST_LEN);
+
+  /* Last time we tried to fetch microdescs, was this directory mirror missing
+   * any mds we asked for? */
+  if (smartlist_contains_string(outdated_dirserver_list, relay_hexdigest)) {
+    return 1;
+  }
+
+  return 0;
+}
+
+/** Reset the list of outdated dirservers. */
+void
+microdesc_reset_outdated_dirservers_list(void)
+{
+  if (!outdated_dirserver_list) {
+    return;
+  }
+
+  SMARTLIST_FOREACH(outdated_dirserver_list, char *, cp, tor_free(cp));
+  smartlist_clear(outdated_dirserver_list);
+}
+
+/****************************************************************************/
+
 /** Write the body of <b>md</b> into <b>f</b>, with appropriate annotations.
  * On success, return the total number of bytes written, and set
  * *<b>annotation_len_out</b> to the number of bytes written as
@@ -789,6 +885,11 @@ microdesc_free_all(void)
     tor_free(the_microdesc_cache->journal_fname);
     tor_free(the_microdesc_cache);
   }
+
+  if (outdated_dirserver_list) {
+    SMARTLIST_FOREACH(outdated_dirserver_list, char *, cp, tor_free(cp));
+    smartlist_free(outdated_dirserver_list);
+  }
 }
 
 /** If there is a microdescriptor in <b>cache</b> whose sha256 digest is
diff --git a/src/or/microdesc.h b/src/or/microdesc.h
index 943873066e..1be12156a4 100644
--- a/src/or/microdesc.h
+++ b/src/or/microdesc.h
@@ -50,5 +50,9 @@ int we_fetch_microdescriptors(const or_options_t *options);
 int we_fetch_router_descriptors(const or_options_t *options);
 int we_use_microdescriptors_for_circuits(const or_options_t *options);
 
-#endif
+void microdesc_note_outdated_dirserver(const char *relay_digest);
+int microdesc_relay_is_outdated_dirserver(const char *relay_digest);
+void microdesc_reset_outdated_dirservers_list(void);
+
+#endif /* !defined(TOR_MICRODESC_H) */
 
diff --git a/src/or/networkstatus.c b/src/or/networkstatus.c
index 997280de52..36e62020e3 100644
--- a/src/or/networkstatus.c
+++ b/src/or/networkstatus.c
@@ -2041,6 +2041,9 @@ networkstatus_set_current_consensus(const char *consensus,
                     "CLOCK_SKEW MIN_SKEW=%ld SOURCE=CONSENSUS", delta);
   }
 
+  /* We got a new consesus. Reset our md fetch fail cache */
+  microdesc_reset_outdated_dirservers_list();
+
   router_dir_info_changed();
 
   result = 0;