Merge remote-tracking branch 'public/no_dup_guards' into maint-0.2.4

changes/bug8231

@@ -0,0 +1,5 @@
+  o Major bugfixes:
+    - When unable to find any working directory nodes to use as a
+      directory guard, give up rather than adding the same non-working
+      nodes to the list over and over. Fixes bug 8231; bugfix on
+      0.2.4.8-alpha.

src/or/circuitbuild.c

@@ -3398,6 +3398,7 @@ choose_good_entry_server(uint8_t purpose, cpath_build_state_t *state)
     });
   }
   /* and exclude current entry guards and their families, if applicable */
+  /*XXXX025 use the using_as_guard flag to accomplish this.*/
   if (options->UseEntryGuards) {
     SMARTLIST_FOREACH(get_entry_guards(), const entry_guard_t *, entry,
       {

src/or/entrynodes.c

@@ -367,13 +367,22 @@ add_an_entry_guard(const node_t *chosen, int reset_status, int prepend,
   } else {
     const routerstatus_t *rs;
     rs = router_pick_directory_server(MICRODESC_DIRINFO|V3_DIRINFO,
-                                      PDS_PREFER_TUNNELED_DIR_CONNS_);
+                                      PDS_PREFER_TUNNELED_DIR_CONNS_|PDS_FOR_GUARD);
     if (!rs)
       return NULL;
     node = node_get_by_id(rs->identity_digest);
     if (!node)
       return NULL;
   }
+  if (node->using_as_guard)
+    return NULL;
+  if (entry_guard_get_by_id_digest(node->identity) != NULL) {
+    log_info(LD_CIRC, "I was about to add a duplicate entry guard.");
+    /* This can happen if we choose a guard, then the node goes away, then
+     * comes back. */
+    ((node_t*) node)->using_as_guard = 1;
+    return NULL;
+  }
   entry = tor_malloc_zero(sizeof(entry_guard_t));
   log_info(LD_CIRC, "Chose %s as new entry guard.",
            node_describe(node));
@@ -391,6 +400,7 @@ add_an_entry_guard(const node_t *chosen, int reset_status, int prepend,
    * this guard. For details, see the Jan 2010 or-dev thread. */
   entry->chosen_on_date = time(NULL) - crypto_rand_int(3600*24*30);
   entry->chosen_by_version = tor_strdup(VERSION);
+  ((node_t*)node)->using_as_guard = 1;
   if (prepend)
     smartlist_insert(entry_guards, 0, entry);
   else
@@ -730,6 +740,21 @@ entry_nodes_should_be_added(void)
   should_add_entry_nodes = 1;
 }
 
+/** Update the using_as_guard fields of all the nodes. We do this after we
+ * remove entry guards from the list: This is the only function that clears
+ * the using_as_guard field. */
+static void
+update_node_guard_status(void)
+{
+  smartlist_t *nodes = nodelist_get_list();
+  SMARTLIST_FOREACH(nodes, node_t *, node, node->using_as_guard = 0);
+  SMARTLIST_FOREACH_BEGIN(entry_guards, entry_guard_t *, entry) {
+    node_t *node = node_get_mutable_by_id(entry->identity);
+    if (node)
+      node->using_as_guard = 1;
+  } SMARTLIST_FOREACH_END(entry);
+}
+
 /** Adjust the entry guards list so that it only contains entries from
  * EntryNodes, adding new entries from EntryNodes to the list as needed. */
 static void
@@ -814,6 +839,8 @@ entry_guards_set_from_config(const or_options_t *options)
   SMARTLIST_FOREACH(old_entry_guards_not_on_list, entry_guard_t *, e,
                     entry_guard_free(e));
 
+  update_node_guard_status();
+
   smartlist_free(entry_nodes);
   smartlist_free(worse_entry_nodes);
   smartlist_free(entry_fps);
@@ -1269,6 +1296,8 @@ entry_guards_parse_state(or_state_t *state, int set, char **msg)
      * few lines, so we don't have to re-dirty it */
     if (remove_obsolete_entry_guards(now))
       entry_guards_dirty = 1;
+
+    update_node_guard_status();
   }
   digestmap_free(added_by, tor_free_);
   return *msg ? -1 : 0;

src/or/or.h

@@ -2249,6 +2249,9 @@ typedef struct node_t {
   /** Local info: we treat this node as if it rejects everything */
   unsigned int rejects_all:1;
 
+  /** Local info: this node is in our list of guards */
+  unsigned int using_as_guard:1;
+
   /* Local info: derived. */
 
   /** True if the IPv6 OR port is preferred over the IPv4 OR port.  */
@@ -4784,6 +4787,10 @@ typedef struct dir_server_t {
 #define PDS_NO_EXISTING_SERVERDESC_FETCH (1<<3)
 #define PDS_NO_EXISTING_MICRODESC_FETCH (1<<4)
 
+/** This node is to be chosen as a directory guard, so don't choose any
+ * node that's currently a guard. */
+#define PDS_FOR_GUARD (1<<5)
+
 #define PDS_PREFER_TUNNELED_DIR_CONNS_ (1<<16)
 
 /** Possible ways to weight routers when choosing one randomly.  See

src/or/routerlist.c

@@ -1150,6 +1150,7 @@ router_pick_directory_server_impl(dirinfo_type_t type, int flags)
   int requireother = ! (flags & PDS_ALLOW_SELF);
   int fascistfirewall = ! (flags & PDS_IGNORE_FASCISTFIREWALL);
   int prefer_tunnel = (flags & PDS_PREFER_TUNNELED_DIR_CONNS_);
+  int for_guard = (flags & PDS_FOR_GUARD);
   int try_excluding = 1, n_excluded = 0;
 
   if (!consensus)
@@ -1189,6 +1190,8 @@ router_pick_directory_server_impl(dirinfo_type_t type, int flags)
     if ((type & MICRODESC_DIRINFO) && !is_trusted &&
         !node->rs->version_supports_microdesc_cache)
       continue;
+    if (for_guard && node->using_as_guard)
+      continue; /* Don't make the same node a guard twice. */
     if (try_excluding &&
         routerset_contains_routerstatus(options->ExcludeNodes, status,
                                         country)) {