Add a circuit_purpose_to_string() function, and use it

We had a circuit_purpose_to_controller_string() function, but it was
pretty coarse-grained and didn't try to be human-readable.

src/or/circuitbuild.c

@@ -2051,8 +2051,9 @@ circuit_send_next_onion_skin(origin_circuit_t *circ)
          */
         if (timediff < 0 || timediff > 2*circ_times.close_ms+1000) {
           log_notice(LD_CIRC, "Strange value for circuit build time: %ldmsec. "
-                              "Assuming clock jump. Purpose %d", timediff,
-                              circ->_base.purpose);
+                              "Assuming clock jump. Purpose %d (%s)", timediff,
+                     circ->_base.purpose,
+                     circuit_purpose_to_string(circ->_base.purpose));
         } else if (!circuit_build_times_disabled()) {
           /* Only count circuit times if the network is live */
           if (circuit_build_times_network_check_live(&circ_times)) {
@@ -2890,8 +2891,9 @@ warn_if_last_router_excluded(origin_circuit_t *circ, const extend_info_t *exit)
     case CIRCUIT_PURPOSE_INTRO_POINT:
     case CIRCUIT_PURPOSE_REND_POINT_WAITING:
     case CIRCUIT_PURPOSE_REND_ESTABLISHED:
-      log_warn(LD_BUG, "Called on non-origin circuit (purpose %d)",
-               (int)purpose);
+      log_warn(LD_BUG, "Called on non-origin circuit (purpose %d, %s)",
+               (int)purpose,
+               circuit_purpose_to_string(purpose));
       return;
     case CIRCUIT_PURPOSE_C_GENERAL:
       if (circ->build_state->is_internal)

src/or/circuitlist.c

@@ -378,6 +378,62 @@ circuit_purpose_to_controller_string(uint8_t purpose)
   }
 }
 
+/** Return a human-readable string for the circuit purpose <b>purpose</b>. */
+const char *
+circuit_purpose_to_string(uint8_t purpose)
+{
+  static char buf[32];
+
+  switch (purpose)
+    {
+    case CIRCUIT_PURPOSE_OR:
+      return "Circuit at relay";
+    case CIRCUIT_PURPOSE_INTRO_POINT:
+      return "Acting as intro point";
+    case CIRCUIT_PURPOSE_REND_POINT_WAITING:
+      return "Acting as rendevous (pending)";
+    case CIRCUIT_PURPOSE_REND_ESTABLISHED:
+      return "Acting as rendevous (established)";
+    case CIRCUIT_PURPOSE_C_GENERAL:
+      return "General-purpose client";
+    case CIRCUIT_PURPOSE_C_INTRODUCING:
+      return "Hidden service client: Connecting to intro point";
+    case CIRCUIT_PURPOSE_C_INTRODUCE_ACK_WAIT:
+      return "Hidden service client: Waiting for ack from intro point";
+    case CIRCUIT_PURPOSE_C_INTRODUCE_ACKED:
+      return "Hidden service client: Received ack from intro point";
+    case CIRCUIT_PURPOSE_C_ESTABLISH_REND:
+      return "Hidden service client: Establishing rendezvous point";
+    case CIRCUIT_PURPOSE_C_REND_READY:
+      return "Hidden service client: Pending rendezvous point";
+    case CIRCUIT_PURPOSE_C_REND_READY_INTRO_ACKED:
+      return "Hidden service client: Pending rendezvous point (ack received)";
+    case CIRCUIT_PURPOSE_C_REND_JOINED:
+      return "Hidden service client: Active rendezvous point";
+    case CIRCUIT_PURPOSE_C_MEASURE_TIMEOUT:
+      return "Measuring circuit timeout";
+
+    case CIRCUIT_PURPOSE_S_ESTABLISH_INTRO:
+      return "Hidden service: Establishing introduction point";
+    case CIRCUIT_PURPOSE_S_INTRO:
+      return "Hidden service: Introduction point";
+    case CIRCUIT_PURPOSE_S_CONNECT_REND:
+      return "Hidden service: Connecting to rendezvous point";
+    case CIRCUIT_PURPOSE_S_REND_JOINED:
+      return "Hidden service: Active rendezvous point";
+
+    case CIRCUIT_PURPOSE_TESTING:
+      return "Testing circuit";
+
+    case CIRCUIT_PURPOSE_CONTROLLER:
+      return "Circuit made by controller";
+
+    default:
+      tor_snprintf(buf, sizeof(buf), "UNKNOWN_%d", (int)purpose);
+      return buf;
+  }
+}
+
 /** Pick a reasonable package_window to start out for our circuits.
  * Originally this was hard-coded at 1000, but now the consensus votes
  * on the answer. See proposal 168. */

src/or/circuitlist.h

@@ -15,6 +15,7 @@
 circuit_t * _circuit_get_global_list(void);
 const char *circuit_state_to_string(int state);
 const char *circuit_purpose_to_controller_string(uint8_t purpose);
+const char *circuit_purpose_to_string(uint8_t purpose);
 void circuit_dump_by_conn(connection_t *conn, int severity);
 void circuit_set_p_circid_orconn(or_circuit_t *circ, circid_t id,
                                  or_connection_t *conn);

src/or/circuituse.c

@@ -392,10 +392,11 @@ circuit_expire_building(void)
             TO_ORIGIN_CIRCUIT(victim)->cpath->state == CPATH_STATE_OPEN;
 
       if (TO_ORIGIN_CIRCUIT(victim)->p_streams != NULL) {
-        log_warn(LD_BUG, "Circuit %d (purpose %d) has timed out, "
+        log_warn(LD_BUG, "Circuit %d (purpose %d, %s) has timed out, "
                  "yet has attached streams!",
                  TO_ORIGIN_CIRCUIT(victim)->global_identifier,
-                 victim->purpose);
+                 victim->purpose,
+                 circuit_purpose_to_string(victim->purpose));
         tor_fragile_assert();
         continue;
       }
@@ -426,9 +427,10 @@ circuit_expire_building(void)
         if (timercmp(&victim->timestamp_created, &extremely_old_cutoff, <)) {
           log_notice(LD_CIRC,
                      "Extremely large value for circuit build timeout: %lds. "
-                     "Assuming clock jump. Purpose %d",
+                     "Assuming clock jump. Purpose %d (%s)",
                      (long)(now.tv_sec - victim->timestamp_created.tv_sec),
-                      victim->purpose);
+                     victim->purpose, 
+                     circuit_purpose_to_string(victim->purpose));
         } else if (circuit_build_times_count_close(&circ_times,
                                             first_hop_succeeded,
                                             victim->timestamp_created.tv_sec)) {
@@ -794,12 +796,11 @@ circuit_expire_old_circuits_clientside(void)
               circ->purpose != CIRCUIT_PURPOSE_S_INTRO) {
             log_notice(LD_CIRC,
                        "Ancient non-dirty circuit %d is still around after "
-                       "%ld milliseconds. Purpose: %d",
+                       "%ld milliseconds. Purpose: %d (%s)",
                        TO_ORIGIN_CIRCUIT(circ)->global_identifier,
                        tv_mdiff(&circ->timestamp_created, &now),
-                       circ->purpose);
-            /* FFFF implement a new circuit_purpose_to_string() so we don't
-             * just print out a number for circ->purpose */
+                       circ->purpose,
+                       circuit_purpose_to_string(circ->purpose));
             TO_ORIGIN_CIRCUIT(circ)->is_ancient = 1;
           }
         }
@@ -1136,8 +1137,9 @@ circuit_launch_by_extend_info(uint8_t purpose,
      * internal circs rather than exit circs? -RD */
     circ = circuit_find_to_cannibalize(purpose, extend_info, flags);
     if (circ) {
-      log_info(LD_CIRC,"Cannibalizing circ '%s' for purpose %d",
-               build_state_get_exit_nickname(circ->build_state), purpose);
+      log_info(LD_CIRC,"Cannibalizing circ '%s' for purpose %d (%s)",
+               build_state_get_exit_nickname(circ->build_state), purpose,
+               circuit_purpose_to_string(purpose));
       circ->_base.purpose = purpose;
       /* reset the birth date of this circ, else expire_building
        * will see it and think it's been trying to build since it