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[tor-commits] [tor/master] relay: Use testing circuit instead of dummy descriptor fetch
commit 4b981407335865795bb99c7297ec49d80455d693
Author: David Goulet <dgoulet@xxxxxxxxxxxxxx>
Date: Fri Sep 18 11:50:12 2020 -0400
relay: Use testing circuit instead of dummy descriptor fetch
Tor now can learn its address from a NETINFO cell coming from an authority.
Thus, instead from launching a dummy descriptor fetch to learn the address
from the directory response (unauthenticated), we simply now launch a one-hop
testing circuit.
Related to #40071
Signed-off-by: David Goulet <dgoulet@xxxxxxxxxxxxxx>
---
src/core/or/circuitlist.h | 4 ++-
src/feature/nodelist/routerlist.c | 69 ++++++++++++++++++++++++---------------
2 files changed, 46 insertions(+), 27 deletions(-)
diff --git a/src/core/or/circuitlist.h b/src/core/or/circuitlist.h
index fd7e22e4c0..3178e6cd0d 100644
--- a/src/core/or/circuitlist.h
+++ b/src/core/or/circuitlist.h
@@ -114,7 +114,9 @@
#define CIRCUIT_PURPOSE_S_HSDIR_POST 20
#define CIRCUIT_PURPOSE_S_HS_MAX_ 20
-/** A testing circuit; not meant to be used for actual traffic. */
+/** A testing circuit; not meant to be used for actual traffic. It is used for
+ * bandwidth measurement, reachability test and address discovery from an
+ * authority using the NETINFO cell. */
#define CIRCUIT_PURPOSE_TESTING 21
/** A controller made this circuit and Tor should not use it. */
#define CIRCUIT_PURPOSE_CONTROLLER 22
diff --git a/src/feature/nodelist/routerlist.c b/src/feature/nodelist/routerlist.c
index 3f6e31bc3a..c1b02b586d 100644
--- a/src/feature/nodelist/routerlist.c
+++ b/src/feature/nodelist/routerlist.c
@@ -65,6 +65,9 @@
#include "app/config/config.h"
#include "core/mainloop/connection.h"
#include "core/mainloop/mainloop.h"
+#include "core/or/circuitlist.h"
+#include "core/or/circuituse.h"
+#include "core/or/extendinfo.h"
#include "core/or/policies.h"
#include "feature/client/bridges.h"
#include "feature/control/control_events.h"
@@ -137,7 +140,7 @@ static int signed_desc_digest_is_recognized(signed_descriptor_t *desc);
static const char *signed_descriptor_get_body_impl(
const signed_descriptor_t *desc,
int with_annotations);
-static void launch_dummy_descriptor_download_as_needed(time_t now,
+static void launch_dummy_circuit_as_needed(time_t now,
const or_options_t *options);
/****************************************************************************/
@@ -2306,7 +2309,7 @@ update_all_descriptor_downloads(time_t now)
return;
update_router_descriptor_downloads(now);
update_microdesc_downloads(now);
- launch_dummy_descriptor_download_as_needed(now, get_options());
+ launch_dummy_circuit_as_needed(now, get_options());
}
/** Clear all our timeouts for fetching v3 directory stuff, and then
@@ -2760,23 +2763,20 @@ update_consensus_router_descriptor_downloads(time_t now, int is_vote,
smartlist_free(no_longer_old);
}
-/** How often should we launch a server/authority request to be sure of getting
+/** How often should we launch a circuit to an authority to be sure of getting
* a guess for our IP? */
-/*XXXX+ this info should come from netinfo cells or something, or we should
- * do this only when we aren't seeing incoming data. see bug 652. */
#define DUMMY_DOWNLOAD_INTERVAL (20*60)
/** As needed, launch a dummy router descriptor fetch to see if our
* address has changed. */
static void
-launch_dummy_descriptor_download_as_needed(time_t now,
- const or_options_t *options)
+launch_dummy_circuit_as_needed(time_t now, const or_options_t *options)
{
- static time_t last_dummy_download = 0;
+ static time_t last_dummy_circuit = 0;
bool have_addr;
tor_addr_t addr_out;
- /* This dummy fetch only matter for relays. */
+ /* This dummy circuit only matter for relays. */
if (!server_mode(options)) {
return;
}
@@ -2784,27 +2784,44 @@ launch_dummy_descriptor_download_as_needed(time_t now,
/* Lookup the address cache to learn if we have a good usable address. We
* still force relays to have an IPv4 so that alone is enough to learn if we
* need a lookup. In case we don't have one, we might want to attempt a
- * dummy fetch to learn our address as a suggestion from an authority. */
+ * dummy circuit to learn our address as a suggestion from an authority. */
have_addr = relay_find_addr_to_publish(options, AF_INET,
RELAY_FIND_ADDR_CACHE_ONLY,
&addr_out);
- /* XXXX+ we could be smarter here; see notes on bug 652. */
- /* If we're a server that doesn't have an address, we rely on directory
- * fetches to learn when our address changes. So if we haven't tried to get
- * any routerdescs in a long time, try a dummy fetch now. */
- if (!have_addr &&
- last_descriptor_download_attempted + DUMMY_DOWNLOAD_INTERVAL < now &&
- last_dummy_download + DUMMY_DOWNLOAD_INTERVAL < now) {
- last_dummy_download = now;
- /* XX/teor - do we want an authority here, because they are less likely
- * to give us the wrong address? (See #17782)
- * I'm leaving the previous behaviour intact, because I don't like
- * the idea of some relays contacting an authority every 20 minutes. */
- directory_get_from_dirserver(DIR_PURPOSE_FETCH_SERVERDESC,
- ROUTER_PURPOSE_GENERAL, "authority.z",
- PDS_RETRY_IF_NO_SERVERS,
- DL_WANT_ANY_DIRSERVER);
+ /* If we're a relay or bridge for which we were unable to discover our
+ * public address, we rely on learning our address from a directory
+ * authority from the NETINFO cell. */
+ if (!have_addr && last_dummy_circuit + DUMMY_DOWNLOAD_INTERVAL < now) {
+ last_dummy_circuit = now;
+
+ const routerstatus_t *rs = router_pick_trusteddirserver(V3_DIRINFO, 0);
+ if (BUG(!rs)) {
+ /* We should really always have trusted directories configured at this
+ * stage. They are loaded early either from default list or the one
+ * given in the configuration file. */
+ return;
+ }
+ const node_t *node = node_get_by_id(rs->identity_digest);
+ if (BUG(!node)) {
+ /* If there is a routerstatus_t, there is a node_t thus this should
+ * never fail. */
+ return;
+ }
+ extend_info_t *ei = extend_info_from_node(node, 1);
+ if (BUG(!ei)) {
+ return;
+ }
+
+ log_debug(LD_GENERAL, "Attempting dummy testing circuit to an authority "
+ "in order to learn our address.");
+
+ /* Launch a one-hop testing circuit to a trusted authority so we can learn
+ * our address through the NETINFO cell. */
+ circuit_launch_by_extend_info(CIRCUIT_PURPOSE_TESTING, ei,
+ CIRCLAUNCH_IS_INTERNAL |
+ CIRCLAUNCH_ONEHOP_TUNNEL);
+ extend_info_free(ei);
}
}
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