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diff --git a/src/feature/control/btrack_orconn.c b/src/feature/control/btrack_orconn.c
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+++ b/src/feature/control/btrack_orconn.c
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+/* Copyright (c) 2007-2019, The Tor Project, Inc. */
+/* See LICENSE for licensing information */
+
+/**
+ * \file btrack_orconn.c
+ * \brief Bootstrap tracker for OR connections
+ *
+ * Track state changes of OR connections, as published by the
+ * connection subsystem.  Also track circuit launch events, because
+ * they're one of the few ways to discover the association between a
+ * channel (and OR connection) and a circuit.
+ *
+ * We track all OR connections that we receive events for, whether or
+ * not they're carrying origin circuits.  (An OR connection might
+ * carry origin circuits only after we first find out about that
+ * connection.)
+ *
+ * All origin ORCONN events update the "any" state variables, while
+ * only application ORCONN events update the "ap" state variables (and
+ * also update the "any") variables.
+ *
+ * We do this because we want to report the first increments of
+ * connection progress as the earliest bootstrap phases.  This results
+ * in a better user experience because failures here translate into
+ * zero or very small amounts of displayed progress, instead of
+ * progress stuck near completion.  The first connection to a relay
+ * might be a one-hop circuit for directory lookups, or it might be a
+ * connection for an application circuit because we already have
+ * enough directory info to build an application circuit.
+ *
+ * We call functions in btrack_orconn_cevent.c to generate the actual
+ * controller events, because some of the state decoding we need to do
+ * is complicated.
+ **/
+
+#include <stdbool.h>
+
+#include "core/or/or.h"
+
+#define BTRACK_ORCONN_PRIVATE
+
+#include "core/or/ocirc_event.h"
+#include "core/or/orconn_event.h"
+#include "feature/control/btrack_orconn.h"
+#include "feature/control/btrack_orconn_cevent.h"
+#include "feature/control/btrack_orconn_maps.h"
+#include "lib/log/log.h"
+
+/** Pair of a best ORCONN GID and with its state */
+typedef struct bto_best_t {
+  uint64_t gid;
+  int state;
+} bto_best_t;
+
+/** GID and state of the best ORCONN we've seen so far */
+static bto_best_t best_any = { 0, -1 };
+/** GID and state of the best application circuit ORCONN we've seen so far */
+static bto_best_t best_ap = { 0, -1 };
+
+/**
+ * Update a cached state of a best ORCONN progress we've seen so far.
+ *
+ * Return true if the new state is better than the old.
+ **/
+static bool
+bto_update_best(const bt_orconn_t *bto, bto_best_t *best, const char *type)
+{
+  if (bto->state < best->state)
+    return false;
+  /* Update even if we won't change best->state, because it's more
+   * recent information that a particular connection transitioned to
+   * that state. */
+  best->gid = bto->gid;
+  if (bto->state > best->state) {
+    log_info(LD_BTRACK, "ORCONN BEST_%s state %d->%d gid=%"PRIu64, type,
+             best->state, bto->state, bto->gid);
+    best->state = bto->state;
+    return true;
+  }
+  return false;
+}
+
+/**
+ * Update cached states of best ORCONN progress we've seen
+ *
+ * Only update the application ORCONN state if we know it's carrying
+ * an application circuit.
+ **/
+static void
+bto_update_bests(const bt_orconn_t *bto)
+{
+  tor_assert(bto->is_orig);
+
+  if (bto_update_best(bto, &best_any, "ANY"))
+    bto_cevent_anyconn(bto);
+  if (!bto->is_onehop && bto_update_best(bto, &best_ap, "AP"))
+    bto_cevent_apconn(bto);
+}
+
+/** Reset cached "best" values */
+static void
+bto_reset_bests(void)
+{
+  best_any.gid = best_ap.gid = 0;
+  best_any.state = best_ap.state = -1;
+}
+
+/**
+ * Update cached states of ORCONNs from the incoming message.  This
+ * message comes from code in connection_or.c.
+ **/
+static void
+bto_state_rcvr(const orconn_state_msg_t *msg)
+{
+  bt_orconn_t *bto;
+
+  bto = bto_find_or_new(msg->gid, msg->chan);
+  log_debug(LD_BTRACK, "ORCONN gid=%"PRIu64" chan=%"PRIu64
+            " proxy_type=%d state=%d",
+            msg->gid, msg->chan, msg->proxy_type, msg->state);
+  bto->proxy_type = msg->proxy_type;
+  bto->state = msg->state;
+  if (bto->is_orig)
+    bto_update_bests(bto);
+}
+
+/**
+ * Delete a cached ORCONN state if we get an incoming message saying
+ * the ORCONN is failed or closed.  This message comes from code in
+ * control.c.
+ **/
+static void
+bto_status_rcvr(const orconn_status_msg_t *msg)
+{
+  switch (msg->status) {
+  case OR_CONN_EVENT_FAILED:
+  case OR_CONN_EVENT_CLOSED:
+    log_info(LD_BTRACK, "ORCONN DELETE gid=%"PRIu64" status=%d reason=%d",
+             msg->gid, msg->status, msg->reason);
+    return bto_delete(msg->gid);
+  default:
+    break;
+  }
+}
+
+/** Dispatch to individual ORCONN message handlers */
+static void
+bto_event_rcvr(const orconn_event_msg_t *msg)
+{
+  switch (msg->type) {
+  case ORCONN_MSGTYPE_STATE:
+    return bto_state_rcvr(&msg->u.state);
+  case ORCONN_MSGTYPE_STATUS:
+    return bto_status_rcvr(&msg->u.status);
+  default:
+    tor_assert(false);
+  }
+}
+
+/**
+ * Create or update a cached ORCONN state for a newly launched
+ * connection, including whether it's launched by an origin circuit
+ * and whether it's a one-hop circuit.
+ **/
+static void
+bto_chan_rcvr(const ocirc_event_msg_t *msg)
+{
+  bt_orconn_t *bto;
+
+  /* Ignore other kinds of origin circuit events; we don't need them */
+  if (msg->type != OCIRC_MSGTYPE_CHAN)
+    return;
+
+  bto = bto_find_or_new(0, msg->u.chan.chan);
+  if (!bto->is_orig || (bto->is_onehop && !msg->u.chan.onehop)) {
+    log_debug(LD_BTRACK, "ORCONN LAUNCH chan=%"PRIu64" onehop=%d",
+              msg->u.chan.chan, msg->u.chan.onehop);
+  }
+  bto->is_orig = true;
+  if (!msg->u.chan.onehop)
+    bto->is_onehop = false;
+  bto_update_bests(bto);
+}
+
+/**
+ * Initialize the hash maps and subscribe to ORCONN and origin
+ * circuit events.
+ **/
+int
+btrack_orconn_init(void)
+{
+  bto_init_maps();
+  orconn_event_subscribe(bto_event_rcvr);
+  ocirc_event_subscribe(bto_chan_rcvr);
+
+  return 0;
+}
+
+/** Clear the hash maps and reset the "best" states */
+void
+btrack_orconn_fini(void)
+{
+  bto_clear_maps();
+  bto_reset_bests();
+  bto_cevent_reset();
+}