[tor-bugs] #20511 [Core Tor/Tor]: add a failsafe where if you're about to serve a consensus that you know is obsolete, don't do it
Tor Bug Tracker & Wiki
blackhole at torproject.org
Sat Nov 5 16:18:43 UTC 2016
#20511: add a failsafe where if you're about to serve a consensus that you know is
obsolete, don't do it
--------------------------+------------------------------------
Reporter: arma | Owner:
Type: enhancement | Status: new
Priority: Medium | Milestone: Tor: 0.3.0.x-final
Component: Core Tor/Tor | Version:
Severity: Normal | Resolution:
Keywords: | Actual Points:
Parent ID: | Points:
Reviewer: | Sponsor:
--------------------------+------------------------------------
Comment (by rubiate):
Will this work? I'm not sure that this is all that's needed or if there's
other places that it needs to be checked.
I thought Tor should warn that this has happened, but probably shouldn't
do it at a normal log-level on every dir request as that could get noisy.
{{{
diff --git a/src/or/directory.c b/src/or/directory.c
index ba6d38c..16e33c5 100644
--- a/src/or/directory.c
+++ b/src/or/directory.c
@@ -2939,6 +2939,32 @@ handle_get_frontpage(dir_connection_t *conn, const
get_handler_args_t *args)
return 0;
}
+/** Warn that the consensus <b>v</b> of type <b>flavor</b> is too old and
will
+ * not be served. Log the message at a lower severity if we have already
+ * warned about this recently.
+ */
+static void
+warn_consensus_is_too_old(networkstatus_t *v, const char *flavor, time_t
now)
+{
+ static time_t warned = 0;
+ int severity;
+ char timestamp[ISO_TIME_LEN+1];
+
+ if (now >= warned + 60 * 60) {
+ severity = LOG_WARN;
+ warned = now;
+ } else {
+ severity = LOG_DEBUG;
+ }
+
+ format_local_iso_time(timestamp, v->valid_until);
+ log_fn(severity, LD_DIRSERV,
+ "Our %s%sconsensus is too old, we will not serve it to clients.
"
+ "It was valid until %s and we continued to serve it for up to 24
"
+ "hours after it expired.",
+ flavor ? flavor : "", flavor ? " " : "", timestamp);
+}
+
/** Helper function for GET /tor/status-vote/current/consensus
*/
static int
@@ -2983,6 +3009,15 @@ handle_get_current_consensus(dir_connection_t
*conn,
v = networkstatus_get_latest_consensus_by_flavor(flav);
+ if (v && !networkstatus_consensus_reasonably_live(v, now)) {
+ write_http_status_line(conn, 404, "Consensus is too old");
+ warn_consensus_is_too_old(v, flavor, now);
+ smartlist_free(dir_fps);
+ geoip_note_ns_response(GEOIP_REJECT_NOT_FOUND);
+ tor_free(flavor);
+ goto done;
+ }
+
if (v && want_fps &&
!client_likes_consensus(v, want_fps)) {
write_http_status_line(conn, 404, "Consensus not signed by
sufficient "
diff --git a/src/or/networkstatus.c b/src/or/networkstatus.c
index ed888fb..7f200b9 100644
--- a/src/or/networkstatus.c
+++ b/src/or/networkstatus.c
@@ -1342,6 +1342,21 @@ networkstatus_get_live_consensus,(time_t now))
return NULL;
}
+/** Determine if <b>consensus</b> is valid or expired recently enough
that
+ * we can still use it.
+ *
+ * Return 1 if the consensus is reasonably live, or 0 if it is too old.
+ */
+int
+networkstatus_consensus_reasonably_live(networkstatus_t *consensus,
time_t now)
+{
+#define REASONABLY_LIVE_TIME (24*60*60)
+ if (now <= consensus->valid_until + REASONABLY_LIVE_TIME)
+ return 1;
+
+ return 0;
+}
+
/* XXXX remove this in favor of get_live_consensus. But actually,
* leave something like it for bridge users, who need to not totally
* lose if they spend a while fetching a new consensus. */
@@ -1350,12 +1365,11 @@ networkstatus_get_live_consensus,(time_t now))
networkstatus_t *
networkstatus_get_reasonably_live_consensus(time_t now, int flavor)
{
-#define REASONABLY_LIVE_TIME (24*60*60)
networkstatus_t *consensus =
networkstatus_get_latest_consensus_by_flavor(flavor);
if (consensus &&
consensus->valid_after <= now &&
- now <= consensus->valid_until+REASONABLY_LIVE_TIME)
+ networkstatus_consensus_reasonably_live(consensus, now))
return consensus;
else
return NULL;
diff --git a/src/or/networkstatus.h b/src/or/networkstatus.h
index 71f36b6..172c0ea 100644
--- a/src/or/networkstatus.h
+++ b/src/or/networkstatus.h
@@ -79,6 +79,8 @@ MOCK_DECL(networkstatus_t
*,networkstatus_get_latest_consensus,(void));
MOCK_DECL(networkstatus_t *,networkstatus_get_latest_consensus_by_flavor,
(consensus_flavor_t f));
MOCK_DECL(networkstatus_t *, networkstatus_get_live_consensus,(time_t
now));
+int networkstatus_consensus_reasonably_live(networkstatus_t *consensus,
+ time_t now);
networkstatus_t *networkstatus_get_reasonably_live_consensus(time_t now,
int flavor);
MOCK_DECL(int, networkstatus_consensus_is_bootstrapping,(time_t now));
}}}
Tests and changes file:
Note there's an existing test that needed to be changed to set the
valid_until time or else it fails for it's consensus being too old.
{{{
diff --git a/changes/20511 b/changes/20511
new file mode 100644
index 0000000..d6e962e
--- /dev/null
+++ b/changes/20511
@@ -0,0 +1,3 @@
+ o Minor feature:
+ - Relays and bridges will now refuse to serve the consensus they have
if
+ they know it is too old for a client to use. Closes ticket 20511.
diff --git a/src/test/test_dir_handle_get.c
b/src/test/test_dir_handle_get.c
index c215fee..cab3fb2 100644
--- a/src/test/test_dir_handle_get.c
+++ b/src/test/test_dir_handle_get.c
@@ -30,6 +30,7 @@
#include "dirserv.h"
#include "torgzip.h"
#include "dirvote.h"
+#include "log_test_helpers.h"
#ifdef _WIN32
/* For mkdir() */
@@ -53,6 +54,7 @@ ENABLE_GCC_WARNING(overlength-strings)
#define NOT_FOUND "HTTP/1.0 404 Not found\r\n\r\n"
#define BAD_REQUEST "HTTP/1.0 400 Bad request\r\n\r\n"
#define SERVER_BUSY "HTTP/1.0 503 Directory busy, try again
later\r\n\r\n"
+#define TOO_OLD "HTTP/1.0 404 Consensus is too old\r\n\r\n"
#define NOT_ENOUGH_CONSENSUS_SIGNATURES "HTTP/1.0 404 " \
"Consensus not signed by sufficient number of requested
authorities\r\n\r\n"
@@ -1617,6 +1619,7 @@
test_dir_handle_get_status_vote_current_consensus_ns_not_enough_sigs(void*
d)
mock_ns_val = tor_malloc_zero(sizeof(networkstatus_t));
mock_ns_val->flavor = FLAV_NS;
mock_ns_val->voters = smartlist_new();
+ mock_ns_val->valid_until = time(NULL);
/* init mock */
init_mock_options();
@@ -1696,6 +1699,63 @@
test_dir_handle_get_status_vote_current_consensus_ns_not_found(void* data)
or_options_free(mock_options); mock_options = NULL;
}
+static void
+test_dir_handle_get_status_vote_current_consensus_too_old(void *data)
+{
+ dir_connection_t *conn = NULL;
+ char *header = NULL;
+ (void)data;
+
+ mock_ns_val = tor_malloc_zero(sizeof(networkstatus_t));
+ mock_ns_val->flavor = FLAV_MICRODESC;
+ mock_ns_val->valid_until = time(NULL) - (60 * 60 * 24) - 1;
+
+ init_mock_options();
+ MOCK(get_options, mock_get_options);
+ MOCK(connection_write_to_buf_impl_, connection_write_to_buf_mock);
+ MOCK(networkstatus_get_latest_consensus_by_flavor,
mock_ns_get_by_flavor);
+
+ conn = new_dir_conn();
+
+ setup_capture_of_logs(LOG_WARN);
+
+ tt_int_op(0, OP_EQ, directory_handle_command_get(conn,
+ GET("/tor/status-vote/current/consensus-microdesc"), NULL, 0));
+
+ fetch_from_buf_http(TO_CONN(conn)->outbuf, &header, MAX_HEADERS_SIZE,
+ NULL, NULL, 1, 0);
+ tt_assert(header);
+ tt_str_op(TOO_OLD, OP_EQ, header);
+
+ expect_log_msg_containing("too old");
+
+ tor_free(header);
+ header = NULL;
+ teardown_capture_of_logs();
+
+ setup_capture_of_logs(LOG_WARN);
+
+ tt_int_op(0, OP_EQ, directory_handle_command_get(conn,
+ GET("/tor/status-vote/current/consensus"), NULL, 0));
+
+ fetch_from_buf_http(TO_CONN(conn)->outbuf, &header, MAX_HEADERS_SIZE,
+ NULL, NULL, 1, 0);
+ tt_assert(header);
+ tt_str_op(TOO_OLD, OP_EQ, header);
+
+ expect_no_log_entry();
+
+ done:
+ teardown_capture_of_logs();
+ UNMOCK(networkstatus_get_latest_consensus_by_flavor);
+ UNMOCK(connection_write_to_buf_impl_);
+ UNMOCK(get_options);
+ connection_free_(TO_CONN(conn));
+ tor_free(header);
+ tor_free(mock_ns_val);
+ or_options_free(mock_options); mock_options = NULL;
+}
+
NS_DECL(int, geoip_get_country_by_addr, (const tor_addr_t *addr));
int
@@ -2481,6 +2541,7 @@ struct testcase_t dir_handle_get_tests[] = {
DIR_HANDLE_CMD(status_vote_next_authority, 0),
DIR_HANDLE_CMD(status_vote_current_consensus_ns_not_enough_sigs, 0),
DIR_HANDLE_CMD(status_vote_current_consensus_ns_not_found, 0),
+ DIR_HANDLE_CMD(status_vote_current_consensus_too_old, 0),
DIR_HANDLE_CMD(status_vote_current_consensus_ns_busy, 0),
DIR_HANDLE_CMD(status_vote_current_consensus_ns, 0),
DIR_HANDLE_CMD(status_vote_current_d_not_found, 0),
}}}
--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/20511#comment:4>
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