[tor-commits] [tor/master] Provide a DROPTIMEOUTS command to drop CBT times

[asn at torproject.org]

commit 6ec01c5f728b0daddebaf8e5364ce0b34027fb5e
Author: Mike Perry <mikeperry-git at torproject.org>
Date:   Sun Jun 7 22:16:25 2020 -0500

    Provide a DROPTIMEOUTS command to drop CBT times
    
    This allows us to reset CBT when we change guards in fixed-guards onionperf
    instances (#33325 and children).
---
 src/core/or/circuitstats.c        |  7 ++-----
 src/core/or/circuitstats.h        |  7 ++++++-
 src/feature/control/control_cmd.c | 30 ++++++++++++++++++++++++++++++
 3 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/src/core/or/circuitstats.c b/src/core/or/circuitstats.c
index 822e5bd30..08d12d0d6 100644
--- a/src/core/or/circuitstats.c
+++ b/src/core/or/circuitstats.c
@@ -53,9 +53,6 @@
 #undef log
 #include <math.h>
 
-static void cbt_control_event_buildtimeout_set(
-                                  const circuit_build_times_t *cbt,
-                                  buildtimeout_set_event_t type);
 static void circuit_build_times_scale_circ_counts(circuit_build_times_t *cbt);
 
 #define CBT_BIN_TO_MS(bin) ((bin)*CBT_BIN_WIDTH + (CBT_BIN_WIDTH/2))
@@ -545,7 +542,7 @@ circuit_build_times_get_initial_timeout(void)
  * Leave estimated parameters, timeout and network liveness intact
  * for future use.
  */
-STATIC void
+void
 circuit_build_times_reset(circuit_build_times_t *cbt)
 {
   memset(cbt->circuit_build_times, 0, sizeof(cbt->circuit_build_times));
@@ -1894,7 +1891,7 @@ circuit_build_times_update_last_circ(circuit_build_times_t *cbt)
   cbt->last_circ_at = approx_time();
 }
 
-static void
+void
 cbt_control_event_buildtimeout_set(const circuit_build_times_t *cbt,
                                    buildtimeout_set_event_t type)
 {
diff --git a/src/core/or/circuitstats.h b/src/core/or/circuitstats.h
index 52c9100f5..a89fc1e96 100644
--- a/src/core/or/circuitstats.h
+++ b/src/core/or/circuitstats.h
@@ -12,6 +12,8 @@
 #ifndef TOR_CIRCUITSTATS_H
 #define TOR_CIRCUITSTATS_H
 
+#include "feature/control/control_events.h"
+
 const circuit_build_times_t *get_circuit_build_times(void);
 circuit_build_times_t *get_circuit_build_times_mutable(void);
 double get_circuit_build_close_time_ms(void);
@@ -49,6 +51,10 @@ double circuit_build_times_close_rate(const circuit_build_times_t *cbt);
 
 void circuit_build_times_update_last_circ(circuit_build_times_t *cbt);
 void circuit_build_times_mark_circ_as_measurement_only(origin_circuit_t *circ);
+void circuit_build_times_reset(circuit_build_times_t *cbt);
+void cbt_control_event_buildtimeout_set(
+                                  const circuit_build_times_t *cbt,
+                                  buildtimeout_set_event_t type);
 
 /** Total size of the circuit timeout history to accumulate.
  * 1000 is approx 2.5 days worth of continual-use circuits. */
@@ -137,7 +143,6 @@ int32_t circuit_build_times_initial_timeout(void);
 STATIC double circuit_build_times_calculate_timeout(circuit_build_times_t *cbt,
                                              double quantile);
 STATIC int circuit_build_times_update_alpha(circuit_build_times_t *cbt);
-STATIC void circuit_build_times_reset(circuit_build_times_t *cbt);
 
 /* Network liveness functions */
 STATIC int circuit_build_times_network_check_changed(
diff --git a/src/feature/control/control_cmd.c b/src/feature/control/control_cmd.c
index d9a38011d..74d542ec6 100644
--- a/src/feature/control/control_cmd.c
+++ b/src/feature/control/control_cmd.c
@@ -20,9 +20,11 @@
 #include "core/or/circuitlist.h"
 #include "core/or/circuituse.h"
 #include "core/or/connection_edge.h"
+#include "core/or/circuitstats.h"
 #include "feature/client/addressmap.h"
 #include "feature/client/dnsserv.h"
 #include "feature/client/entrynodes.h"
+#include "feature/control/control_events.h"
 #include "feature/control/control.h"
 #include "feature/control/control_auth.h"
 #include "feature/control/control_cmd.h"
@@ -1396,6 +1398,33 @@ handle_control_dropguards(control_connection_t *conn,
   return 0;
 }
 
+static const control_cmd_syntax_t droptimeouts_syntax = {
+  .max_args = 0,
+};
+
+/** Implementation for the DROPTIMEOUTS command. */
+static int
+handle_control_droptimeouts(control_connection_t *conn,
+                          const control_cmd_args_t *args)
+{
+  (void) args; /* We don't take arguments. */
+
+  static int have_warned = 0;
+  if (! have_warned) {
+    log_warn(LD_CONTROL, "DROPTIMEOUTS is dangerous; make sure you understand "
+             "the risks before using it. It may be removed in a future "
+             "version of Tor.");
+    have_warned = 1;
+  }
+
+  circuit_build_times_reset(get_circuit_build_times_mutable());
+  send_control_done(conn);
+  cbt_control_event_buildtimeout_set(get_circuit_build_times(),
+                                     BUILDTIMEOUT_SET_EVENT_RESET);
+
+  return 0;
+}
+
 static const char *hsfetch_keywords[] = {
   "SERVER", NULL,
 };
@@ -2331,6 +2360,7 @@ static const control_cmd_def_t CONTROL_COMMANDS[] =
   ONE_LINE(protocolinfo, 0),
   ONE_LINE(authchallenge, CMD_FL_WIPE),
   ONE_LINE(dropguards, 0),
+  ONE_LINE(droptimeouts, 0),
   ONE_LINE(hsfetch, 0),
   MULTLINE(hspost, 0),
   ONE_LINE(add_onion, CMD_FL_WIPE),