A Bridge Authority should compute flag thresholds

As a bridge authority, before we create our networkstatus document, we
should compute the thresholds needed for the various status flags
assigned to each bridge based on the status of all other bridges. We
then add these thresholds to the networkstatus document for easy access.
Fixes for #1117 and #9859.

changes/bug9859

@@ -0,0 +1,6 @@
+  o Minor Feature
+
+    - Assign status flags to bridges based on thresholds calculated
+      over all bridges. Fixes bug 9859.
+    - Add threshold cutoffs to the networkstatus document created by
+      the Bridge Authority. Fixes bug 1117.

src/or/dirserv.c

@@ -1957,6 +1957,10 @@ dirserv_compute_performance_thresholds(routerlist_t *rl,
 
   /* Now, fill in the arrays. */
   SMARTLIST_FOREACH_BEGIN(nodelist_get_list(), node_t *, node) {
+    if (options->BridgeAuthoritativeDir &&
+        node->ri &&
+        node->ri->purpose != ROUTER_PURPOSE_BRIDGE)
+      continue;
     if (router_counts_toward_thresholds(node, now, omit_as_sybil,
                                         require_mbw)) {
       routerinfo_t *ri = node->ri;
@@ -2071,6 +2075,21 @@ dirserv_compute_performance_thresholds(routerlist_t *rl,
   tor_free(wfus);
 }
 
+/* Use dirserv_compute_performance_thresholds() to compute the thresholds
+ * for the status flags, specifically for bridges.
+ *
+ * This is only called by a Bridge Authority from
+ * networkstatus_getinfo_by_purpose().
+ */
+void
+dirserv_compute_bridge_flag_thresholds(routerlist_t *rl)
+{
+
+  digestmap_t *omit_as_sybil = digestmap_new();
+  dirserv_compute_performance_thresholds(rl, omit_as_sybil);
+  digestmap_free(omit_as_sybil, NULL);
+}
+
 /** Measured bandwidth cache entry */
 typedef struct mbw_cache_entry_s {
   long mbw_kb;

src/or/dirserv.h

@@ -51,6 +51,7 @@ int list_server_status_v1(smartlist_t *routers, char **router_status_out,
 int dirserv_dump_directory_to_string(char **dir_out,
                                      crypto_pk_t *private_key);
 char *dirserv_get_flag_thresholds_line(void);
+void dirserv_compute_bridge_flag_thresholds(routerlist_t *rl);
 
 int directory_fetches_from_authorities(const or_options_t *options);
 int directory_fetches_dir_info_early(const or_options_t *options);

src/or/networkstatus.c

@@ -2171,9 +2171,17 @@ networkstatus_dump_bridge_status_to_file(time_t now)
   char *status = networkstatus_getinfo_by_purpose("bridge", now);
   const or_options_t *options = get_options();
   char *fname = NULL;
+  char *thresholds = NULL, *thresholds_and_status = NULL;
+  routerlist_t *rl = router_get_routerlist();
+  dirserv_compute_bridge_flag_thresholds(rl);
+  thresholds = dirserv_get_flag_thresholds_line();
+  tor_asprintf(&thresholds_and_status, "flag-thresholds %s\n%s",
+               thresholds, status);
   tor_asprintf(&fname, "%s"PATH_SEPARATOR"networkstatus-bridges",
                options->DataDirectory);
-  write_str_to_file(fname,status,0);
+  write_str_to_file(fname,thresholds_and_status,0);
+  tor_free(thresholds);
+  tor_free(thresholds_and_status);
   tor_free(fname);
   tor_free(status);
 }