From a8297cdbd3324ac707165ae9922ecf478c4608a1 Mon Sep 17 00:00:00 2001 From: Roger Dingledine Date: Wed, 25 Jan 2012 20:18:51 -0500 Subject: use microdescriptors if *any* of our bridges can handle them Now as we move into a future where most bridges can handle microdescs we will generally find ourselves using them, rather than holding back just because one of our bridges doesn't use them. --- src/or/circuitbuild.c | 3 ++- src/or/directory.c | 12 ++++++----- src/or/entrynodes.c | 59 ++++++++++++++++++++++++++++++++++----------------- src/or/entrynodes.h | 5 +++-- src/or/microdesc.c | 4 ++-- 5 files changed, 53 insertions(+), 30 deletions(-) (limited to 'src/or') diff --git a/src/or/circuitbuild.c b/src/or/circuitbuild.c index 5a5a3afea..8c86aac90 100644 --- a/src/or/circuitbuild.c +++ b/src/or/circuitbuild.c @@ -25,6 +25,7 @@ #include "directory.h" #include "entrynodes.h" #include "main.h" +#include "microdesc.h" #include "networkstatus.h" #include "nodelist.h" #include "onion.h" @@ -3372,7 +3373,7 @@ choose_good_entry_server(uint8_t purpose, cpath_build_state_t *state) (purpose != CIRCUIT_PURPOSE_TESTING || options->BridgeRelay)) { /* This request is for an entry server to use for a regular circuit, * and we use entry guard nodes. Just return one of the guard nodes. */ - return choose_random_entry(state); + return choose_random_entry(state, 0); } excluded = smartlist_new(); diff --git a/src/or/directory.c b/src/or/directory.c index c10141844..c1bbe6bd8 100644 --- a/src/or/directory.c +++ b/src/or/directory.c @@ -472,12 +472,14 @@ directory_get_from_dirserver(uint8_t dir_purpose, uint8_t router_purpose, if (options->UseBridges && type != BRIDGE_DIRINFO) { /* We want to ask a running bridge for which we have a descriptor. * - * Be careful here: we should only ask questions that we know our - * bridges can answer. So far we're solving that by backing off to - * the behavior supported by our oldest bridge; see for example - * any_bridges_dont_support_microdescriptors(). + * When we ask choose_random_entry() for a bridge, we specify that + * we're going to be using it for a dir fetch: if any of our bridges + * can handle microdescriptor questions, we'll get one of the ones + * that can. */ - const node_t *node = choose_random_entry(NULL); + /* XXX024 Not all bridges handle conditional consensus downloading, + * so, for now, never assume the server supports that. -PP */ + const node_t *node = choose_random_entry(NULL, 1); if (node && node->ri) { /* every bridge has a routerinfo. */ tor_addr_t addr; diff --git a/src/or/entrynodes.c b/src/or/entrynodes.c index 4ca56cbac..d029d8593 100644 --- a/src/or/entrynodes.c +++ b/src/or/entrynodes.c @@ -23,6 +23,7 @@ #include "directory.h" #include "entrynodes.h" #include "main.h" +#include "microdesc.h" #include "nodelist.h" #include "policies.h" #include "router.h" @@ -63,7 +64,8 @@ static int entry_guards_dirty = 0; static void bridge_free(bridge_info_t *bridge); static const node_t *choose_random_entry_impl(cpath_build_state_t *state, int for_directory, - dirinfo_type_t dirtype); + dirinfo_type_t dirtype, + int prefer_microdescs); /** Return the list of entry guards, creating it if necessary. */ const smartlist_t * @@ -829,15 +831,33 @@ entry_list_is_constrained(const or_options_t *options) return 0; } +/** Return true iff this node can answer directory questions about + * microdescriptors. */ +static int +node_understands_microdescriptors(const node_t *node) +{ + tor_assert(node); + if (node->rs && node->rs->version_supports_microdesc_cache) + return 1; + if (node->ri && tor_version_supports_microdescriptors(node->ri->platform)) + return 1; + return 0; +} + /** Pick a live (up and listed) entry guard from entry_guards. If * state is non-NULL, this is for a specific circuit -- * make sure not to pick this circuit's exit or any node in the * exit's family. If state is NULL, we're looking for a random - * guard (likely a bridge). */ + * guard (likely a bridge). + * + * If the prefer_microdescs flag is set, we are looking for a bridge to + * use for directory fetching and pick a bridge that supports microdescriptors + * if we know any that do so. + */ const node_t * -choose_random_entry(cpath_build_state_t *state) +choose_random_entry(cpath_build_state_t *state, int prefer_microdescs) { - return choose_random_entry_impl(state, 0, 0); + return choose_random_entry_impl(state, 0, 0, prefer_microdescs); } /** Pick a live (up and listed) directory guard from entry_guards for @@ -845,13 +865,13 @@ choose_random_entry(cpath_build_state_t *state) const node_t * choose_random_dirguard(dirinfo_type_t type) { - return choose_random_entry_impl(NULL, 1, type); + return choose_random_entry_impl(NULL, 1, type, 0); } /** Helper for choose_random{entry,dirguard}. */ static const node_t * choose_random_entry_impl(cpath_build_state_t *state, int for_directory, - dirinfo_type_t dirinfo_type) + dirinfo_type_t dirinfo_type, int prefer_microdescs) { const or_options_t *options = get_options(); smartlist_t *live_entry_guards = smartlist_new(); @@ -903,6 +923,10 @@ choose_random_entry_impl(cpath_build_state_t *state, int for_directory, continue; /* don't pick the same node for entry and exit */ if (consider_exit_family && smartlist_contains(exit_family, node)) continue; /* avoid relays that are family members of our exit */ + if (prefer_microdescs && + we_use_microdescriptors_for_circuits(options) && + !node_understands_microdescriptors(node)) + continue; /* this node won't be able to answer our dir questions */ #if 0 /* since EntryNodes is always strict now, this clause is moot */ if (options->EntryNodes && !routerset_contains_node(options->EntryNodes, node)) { @@ -1982,7 +2006,7 @@ int any_bridge_descriptors_known(void) { tor_assert(get_options()->UseBridges); - return choose_random_entry(NULL)!=NULL ? 1 : 0; + return choose_random_entry(NULL, 0)!=NULL ? 1 : 0; } /** Return 1 if there are any directory conns fetching bridge descriptors @@ -2064,29 +2088,24 @@ entries_retry_all(const or_options_t *options) entries_retry_helper(options, 1); } -/** Return true if we've ever had a bridge running a Tor version that can't - * provide microdescriptors to us. In that case fall back to asking for - * full descriptors. Eventually all bridges will support microdescriptors - * and we can take this check out; see bug 4013. */ +/** Return true if at least one of our bridges runs a Tor version that can + * provide microdescriptors to us. If not, we'll fall back to asking for + * full descriptors. */ int -any_bridges_dont_support_microdescriptors(void) +any_bridge_supports_microdescriptors(void) { const node_t *node; - static int ever_answered_yes = 0; if (!get_options()->UseBridges || !entry_guards) return 0; - if (ever_answered_yes) - return 1; /* if we ever answer 'yes', always answer 'yes' */ SMARTLIST_FOREACH_BEGIN(entry_guards, entry_guard_t *, e) { node = node_get_by_id(e->identity); - if (node && node->ri && + if (node && node->is_running && node_is_bridge(node) && node_is_a_configured_bridge(node) && - !tor_version_supports_microdescriptors(node->ri->platform)) { + node_understands_microdescriptors(node)) { /* This is one of our current bridges, and we know enough about - * it to know that it won't be able to answer our microdescriptor + * it to know that it will be able to answer our microdescriptor * questions. */ - ever_answered_yes = 1; - return 1; + return 1; } } SMARTLIST_FOREACH_END(e); return 0; diff --git a/src/or/entrynodes.h b/src/or/entrynodes.h index e6c973c95..8ed429c8f 100644 --- a/src/or/entrynodes.h +++ b/src/or/entrynodes.h @@ -78,7 +78,8 @@ int entry_guard_register_connect_status(const char *digest, int succeeded, int mark_relay_status, time_t now); void entry_nodes_should_be_added(void); int entry_list_is_constrained(const or_options_t *options); -const node_t *choose_random_entry(cpath_build_state_t *state); +const node_t *choose_random_entry(cpath_build_state_t *state, + int prefer_microdescs); const node_t *choose_random_dirguard(dirinfo_type_t t); int entry_guards_parse_state(or_state_t *state, int set, char **msg); void entry_guards_update_state(or_state_t *state); @@ -104,7 +105,7 @@ int any_pending_bridge_descriptor_fetches(void); int entries_known_but_down(const or_options_t *options); void entries_retry_all(const or_options_t *options); -int any_bridges_dont_support_microdescriptors(void); +int any_bridge_supports_microdescriptors(void); void entry_guards_free_all(void); diff --git a/src/or/microdesc.c b/src/or/microdesc.c index e99b3ebe7..ac48930fa 100644 --- a/src/or/microdesc.c +++ b/src/or/microdesc.c @@ -730,9 +730,9 @@ we_use_microdescriptors_for_circuits(const or_options_t *options) int ret = options->UseMicrodescriptors; if (ret == -1) { /* UseMicrodescriptors is "auto"; we need to decide: */ - /* If we are configured to use bridges and one of our bridges doesn't + /* If we are configured to use bridges and none of our bridges * know what a microdescriptor is, the answer is no. */ - if (options->UseBridges && any_bridges_dont_support_microdescriptors()) + if (options->UseBridges && !any_bridge_supports_microdescriptors()) return 0; /* Otherwise, we decide that we'll use microdescriptors iff we are * not a server, and we're not autofetching everything. */ -- cgit v1.2.3