src/feature/control/btrack_circuit.c

   1 /* Copyright (c) 2007-2021, The Tor Project, Inc. */
   2 /* See LICENSE for licensing information */
   3
   4 /**
   5  * \file btrack_circuit.c
   6  * \brief Bootstrap tracker for origin circuits
   7  *
   8  * Track state changes of origin circuits, as published by the circuit
   9  * subsystem.
  10  **/
  11
  12 #include "core/or/or.h"
  13
  14 #include "core/or/ocirc_event.h"
  15
  16 #include "feature/control/btrack_circuit.h"
  17 #include "feature/control/control.h"
  18 #include "lib/log/log.h"
  19
  20 /** Pair of a best origin circuit GID with its state or status */
  21 typedef struct btc_best_t {
  22   uint32_t gid;
  23   int val;
  24 } btc_best_t;
  25
  26 /** GID and state of the best origin circuit we've seen so far */
  27 static btc_best_t best_any_state = { 0, -1 };
  28 /** GID and state of the best application circuit we've seen so far */
  29 static btc_best_t best_ap_state = { 0, -1 };
  30 /** GID and status of the best origin circuit we've seen so far */
  31 static btc_best_t best_any_evtype = { 0, -1 };
  32 /** GID and status of the best application circuit we've seen so far */
  33 static btc_best_t best_ap_evtype = { 0, -1 };
  34
  35 /** Reset cached "best" values */
  36 static void
  37 btc_reset_bests(void)
  38 {
  39   best_any_state.gid = best_ap_state.gid = 0;
  40   best_any_state.val = best_ap_state.val = -1;
  41   best_any_evtype.gid = best_ap_state.gid = 0;
  42   best_any_evtype.val = best_ap_evtype.val = -1;
  43 }
  44
  45 /** True if @a state is a "better" origin circuit state than @a best->val */
  46 static bool
  47 btc_state_better(int state, const btc_best_t *best)
  48 {
  49   return state > best->val;
  50 }
  51
  52 /**
  53  * Definine an ordering on circuit status events
  54  *
  55  * The CIRC_EVENT_ constants aren't sorted in a useful order, so this
  56  * array helps to decode them.  This approach depends on the statuses
  57  * being nonnegative and dense.
  58  **/
  59 static int circ_event_order[] = {
  60   [CIRC_EVENT_FAILED] = -1,
  61   [CIRC_EVENT_CLOSED] = -1,
  62   [CIRC_EVENT_LAUNCHED] = 1,
  63   [CIRC_EVENT_EXTENDED] = 2,
  64   [CIRC_EVENT_BUILT] = 3,
  65 };
  66 #define N_CIRC_EVENT_ORDER \
  67   (sizeof(circ_event_order) / sizeof(circ_event_order[0]))
  68
  69 /** True if @a state is a "better" origin circuit event status than @a
  70     best->val */
  71 static bool
  72 btc_evtype_better(int state, const btc_best_t *best)
  73 {
  74   if (state < 0)
  75     return false;
  76   if (best->val < 0)
  77     return true;
  78
  79   tor_assert(state >= 0 && (unsigned)state < N_CIRC_EVENT_ORDER);
  80   tor_assert(best->val >= 0 && (unsigned)best->val < N_CIRC_EVENT_ORDER);
  81   return circ_event_order[state] > circ_event_order[best->val];
  82 }
  83
  84 static bool
  85 btc_update_state(const ocirc_state_msg_t *msg, btc_best_t *best,
  86                  const char *type)
  87 {
  88   if (btc_state_better(msg->state, best)) {
  89     log_info(LD_BTRACK, "CIRC BEST_%s state %d->%d gid=%"PRIu32, type,
  90              best->val, msg->state, msg->gid);
  91     best->gid = msg->gid;
  92     best->val = msg->state;
  93     return true;
  94   }
  95   return false;
  96 }
  97
  98 static bool
  99 btc_update_evtype(const ocirc_cevent_msg_t *msg, btc_best_t *best,
 100                   const char *type)
 101 {
 102   if (btc_evtype_better(msg->evtype, best)) {
 103     log_info(LD_BTRACK, "CIRC BEST_%s evtype %d->%d gid=%"PRIu32, type,
 104              best->val, msg->evtype, msg->gid);
 105     best->gid = msg->gid;
 106     best->val = msg->evtype;
 107     return true;
 108   }
 109   return false;
 110 }
 111
 112 DECLARE_SUBSCRIBE(ocirc_state, btc_state_rcvr);
 113 DECLARE_SUBSCRIBE(ocirc_cevent, btc_cevent_rcvr);
 114 DECLARE_SUBSCRIBE(ocirc_chan, btc_chan_rcvr);
 115
 116 static void
 117 btc_state_rcvr(const msg_t *msg, const ocirc_state_msg_t *arg)
 118 {
 119   (void)msg;
 120   log_debug(LD_BTRACK, "CIRC gid=%"PRIu32" state=%d onehop=%d",
 121             arg->gid, arg->state, arg->onehop);
 122
 123   btc_update_state(arg, &best_any_state, "ANY");
 124   if (arg->onehop)
 125     return;
 126   btc_update_state(arg, &best_ap_state, "AP");
 127 }
 128
 129 static void
 130 btc_cevent_rcvr(const msg_t *msg, const ocirc_cevent_msg_t *arg)
 131 {
 132   (void)msg;
 133   log_debug(LD_BTRACK, "CIRC gid=%"PRIu32" evtype=%d reason=%d onehop=%d",
 134             arg->gid, arg->evtype, arg->reason, arg->onehop);
 135
 136   btc_update_evtype(arg, &best_any_evtype, "ANY");
 137   if (arg->onehop)
 138     return;
 139   btc_update_evtype(arg, &best_ap_evtype, "AP");
 140 }
 141
 142 static void
 143 btc_chan_rcvr(const msg_t *msg, const ocirc_chan_msg_t *arg)
 144 {
 145   (void)msg;
 146   log_debug(LD_BTRACK, "CIRC gid=%"PRIu32" chan=%"PRIu64" onehop=%d",
 147             arg->gid, arg->chan, arg->onehop);
 148 }
 149
 150 int
 151 btrack_circ_add_pubsub(pubsub_connector_t *connector)
 152 {
 153   if (DISPATCH_ADD_SUB(connector, ocirc, ocirc_chan))
 154     return -1;
 155   if (DISPATCH_ADD_SUB(connector, ocirc, ocirc_cevent))
 156     return -1;
 157   if (DISPATCH_ADD_SUB(connector, ocirc, ocirc_state))
 158     return -1;
 159   return 0;
 160 }
 161
 162 void
 163 btrack_circ_fini(void)
 164 {
 165   btc_reset_bests();
 166 }