Address Nick's comments.

- Add a changes/ file.
- Make it compile under --enable-gcc-warnings.
- Update the file-level documentation of src/or/transports.c.
- Only update descriptor if at least a managed proxy was configured.
- Add our external IP address to the extra-info descriptor instead of 0.0.0.0.

changes/bug3589

@@ -0,0 +1,3 @@
+  o Major features:
+    - Bridges now report the pluggable transports they support to the
+      bridge authority. Implements ticket 3589.

src/or/circuitbuild.h

@@ -12,8 +12,6 @@
 #ifndef _TOR_CIRCUITBUILD_H
 #define _TOR_CIRCUITBUILD_H
 
-#include "transports.h"
-
 char *circuit_list_path(origin_circuit_t *circ, int verbose);
 char *circuit_list_path_for_controller(origin_circuit_t *circ);
 void circuit_log_path(int severity, unsigned int domain,
@@ -136,6 +134,10 @@ void circuit_build_times_network_circ_success(circuit_build_times_t *cbt);
 /* DOCDOC circuit_build_times_get_bw_scale */
 int circuit_build_times_get_bw_scale(networkstatus_t *ns);
 
+/* DOCDOC find_transport_name_by_bridge_addrport */
+const char *find_transport_name_by_bridge_addrport(const tor_addr_t *addr,
+                                                   uint16_t port);
+typedef struct transport_t transport_t;
 int find_transport_by_bridge_addrport(const tor_addr_t *addr, uint16_t port,
                                       const transport_t **transport);
 

src/or/connection.c

@@ -34,6 +34,7 @@
 #include "rendcommon.h"
 #include "rephist.h"
 #include "router.h"
+#include "transports.h"
 #include "routerparse.h"
 
 #ifdef USE_BUFFEREVENTS

src/or/router.c

@@ -27,6 +27,7 @@
 #include "router.h"
 #include "routerlist.h"
 #include "routerparse.h"
+#include "transports.h"
 
 /**
  * \file router.c

src/or/transports.c

@@ -39,13 +39,17 @@
  * transport_t structs.
  *
  * When the managed proxy stops spitting METHOD lines (signified by a
- * '{S,C}METHODS DONE' message) we register all the transports
- * collected to the circuitbuild.c subsystem. At this point, the
- * pointers to transport_t can be transformed into dangling pointers
- * at any point by the circuitbuild.c subsystem, and so we replace all
- * transport_t pointers with strings describing the transport names.
- * We can still go from a transport name to a transport_t using the
- * fact that each transport name uniquely identifies a transport_t.
+ * '{S,C}METHODS DONE' message) we pass copies of its transports to
+ * the bridge subsystem. We keep copies of the 'transport_t's on the
+ * managed proxy to be able to associate the proxy with its
+ * transports, and we pass copies to the bridge subsystem so that
+ * transports can be associated with bridges.
+ * [ XXX We should try see whether the two copies are really needed
+ * and maybe cut it into a single copy of the 'transport_t' shared
+ * between the managed proxy and the bridge subsystem. Preliminary
+ * analysis shows that both copies are needed with the current code
+ * logic, because of race conditions that can cause dangling
+ * pointers. ]
  *
  * <b>In even more detail, this is what happens when a SIGHUP
  * occurs:</b>
@@ -530,6 +534,7 @@ launch_managed_proxy(managed_proxy_t *mp)
 void
 pt_configure_remaining_proxies(void)
 {
+  int at_least_a_proxy_config_finished = 0;
   smartlist_t *tmp = smartlist_new();
 
   log_debug(LD_CONFIG, "Configuring remaining managed proxies (%d)!",
@@ -567,13 +572,16 @@ pt_configure_remaining_proxies(void)
     if (!proxy_configuration_finished(mp))
       configure_proxy(mp);
 
+    if (proxy_configuration_finished(mp))
+      at_least_a_proxy_config_finished = 1;
+
   } SMARTLIST_FOREACH_END(mp);
 
   smartlist_free(tmp);
   check_if_restarts_needed = 0;
   assert_unconfigured_count_ok();
 
-  if (!pt_proxies_configuration_pending())
+  if (at_least_a_proxy_config_finished)
     mark_my_descriptor_dirty("configured managed proxies");
 }
 
@@ -1400,9 +1408,22 @@ pt_get_extra_info_descriptor_string(void)
     tor_assert(mp->transports);
 
     SMARTLIST_FOREACH_BEGIN(mp->transports, const transport_t *, t) {
+      /* If the transport proxy returned "0.0.0.0" as its address, and
+       * we know our external IP address, use it. Otherwise, use the
+       * returned address. */
+      const char *addr_str = fmt_addr(&t->addr);
+      uint32_t external_ip_address = 0;
+      if (tor_addr_is_null(&t->addr) &&
+          router_pick_published_address(get_options(),
+                                        &external_ip_address) >= 0) {
+        /* returned addr was 0.0.0.0 and we found our external IP
+           address: use it. */
+        addr_str = fmt_addr32(external_ip_address);
+      }
+
       smartlist_add_asprintf(string_chunks,
                              "transport %s %s:%u",
-                             t->name, fmt_addr(&t->addr), t->port);
+                             t->name, addr_str, t->port);
     } SMARTLIST_FOREACH_END(t);
 
   } SMARTLIST_FOREACH_END(mp);

src/or/transports.h

@@ -12,12 +12,13 @@
 #define TOR_TRANSPORTS_H
 
 /** Represents a pluggable transport used by a bridge. */
-typedef struct {
+typedef struct transport_t {
   /** SOCKS version: One of PROXY_SOCKS4, PROXY_SOCKS5. */
   int socks_version;
   /** Name of pluggable transport protocol */
   char *name;
-  /** Address of proxy */
+  /** The IP address where the transport bound and is waiting for
+   * connections. */
   tor_addr_t addr;
   /** Port of proxy */
   uint16_t port;