[tor-commits] [tor/master] use microdescriptors if *any* of our bridges can handle them
nickm at torproject.org
nickm at torproject.org
Fri Feb 15 21:04:00 UTC 2013
commit a8297cdbd3324ac707165ae9922ecf478c4608a1
Author: Roger Dingledine <arma at torproject.org>
Date: Wed Jan 25 20:18:51 2012 -0500
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.
---
changes/feature4994 | 7 +++++
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 +-
6 files changed, 60 insertions(+), 30 deletions(-)
diff --git a/changes/feature4994 b/changes/feature4994
new file mode 100644
index 0000000..4fa0e03
--- /dev/null
+++ b/changes/feature4994
@@ -0,0 +1,7 @@
+ o Minor features:
+ - Teach bridge-using clients to avoid 0.2.2 bridges when making
+ microdescriptor-related dir requests, and only fall back to normal
+ descriptors if none of their bridges can handle microdescriptors
+ (as opposed to the fix in ticket 4013, which caused them to fall
+ back to normal descriptors if *any* of their bridges preferred
+ them). Resolves ticket 4994.
diff --git a/src/or/circuitbuild.c b/src/or/circuitbuild.c
index 5a5a3af..8c86aac 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 c101418..c1bbe6b 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 4ca56cb..d029d85 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
* <b>state</b> 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 <b>state</b> 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 e6c973c..8ed429c 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 e99b3eb..ac48930 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. */
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