commit 91027218e29090b18d42e1868367cc2a9e149900 Author: Nick Mathewson nickm@torproject.org Date: Thu Feb 14 11:48:47 2013 -0500

Add some code to bluntly prevent duplicate guards from getting added

Apparently something in the directory guard code made it possible for the same node to get added as a guard over and over when there were no actual running guard nodes. --- src/or/entrynodes.c | 29 +++++++++++++++++++++++++++++ src/or/or.h | 3 +++ 2 files changed, 32 insertions(+), 0 deletions(-)

diff --git a/src/or/entrynodes.c b/src/or/entrynodes.c index 4ca56cb..3e471ed 100644 --- a/src/or/entrynodes.c +++ b/src/or/entrynodes.c @@ -369,6 +369,15 @@ add_an_entry_guard(const node_t *chosen, int reset_status, int prepend, 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)); @@ -384,6 +393,7 @@ 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 @@ -723,6 +733,21 @@ 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 @@ -807,6 +832,8 @@ 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); @@ -1231,6 +1258,8 @@ 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; diff --git a/src/or/or.h b/src/or/or.h index 04640d0..df69674 100644 --- a/src/or/or.h +++ b/src/or/or.h @@ -2233,6 +2233,9 @@ 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. */