Include a flag-thresholds line in each vote to describe flag cutoffs

Implements ticket 8151.

changes/bug8151

@@ -0,0 +1,5 @@
+  o Minor features (directory authority):
+    - Include inside each vote a statement of the performance
+      thresholds that made the authority vote for its flags. Implements
+      ticket 8151.
+ 

src/or/dirserv.c

@@ -2059,6 +2059,30 @@ dirserv_compute_performance_thresholds(routerlist_t *rl,
   tor_free(wfus);
 }
 
+/** Give a statement of our current performance thresholds for inclusion
+ * in a vote document. */
+char *
+dirserv_get_flag_thresholds_line(void)
+{
+  char *result=NULL;
+  tor_asprintf(&result,
+      "stable-uptime=%lu stable-mtbf=%lu "
+      "fast-speed=%lu "
+      "guard-wfu=%.03f%% guard-tk=%lu "
+      "guard-bw-inc-exits=%lu guard-bw-exc-exits=%lu "
+      "enough-mtbf=%d",
+      (unsigned long)stable_uptime,
+      (unsigned long)stable_mtbf,
+      (unsigned long)fast_bandwidth,
+      guard_wfu*100,
+      (unsigned long)guard_tk,
+      (unsigned long)guard_bandwidth_including_exits,
+      (unsigned long)guard_bandwidth_excluding_exits,
+      enough_mtbf_info ? 1 : 0);
+
+  return result;
+}
+
 /** Given a platform string as in a routerinfo_t (possibly null), return a
  * newly allocated version string for a networkstatus document, or NULL if the
  * platform doesn't give a Tor version. */

src/or/dirserv.h

@@ -70,6 +70,7 @@ int list_server_status_v1(smartlist_t *routers, char **router_status_out,
                           int for_controller);
 int dirserv_dump_directory_to_string(char **dir_out,
                                      crypto_pk_t *private_key);
+char *dirserv_get_flag_thresholds_line(void);
 
 int directory_fetches_from_authorities(const or_options_t *options);
 int directory_fetches_dir_info_early(const or_options_t *options);

src/or/dirvote.c

@@ -134,6 +134,8 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
     char fu[ISO_TIME_LEN+1];
     char vu[ISO_TIME_LEN+1];
     char *flags = smartlist_join_strings(v3_ns->known_flags, " ", 0, NULL);
+    /* XXXX Abstraction violation: should be pulling a field out of v3_ns.*/
+    char *flag_thresholds = dirserv_get_flag_thresholds_line();
     char *params;
     authority_cert_t *cert = v3_ns->cert;
     char *methods =
@@ -160,6 +162,7 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
                  "voting-delay %d %d\n"
                  "%s" /* versions */
                  "known-flags %s\n"
+                 "flag-thresholds %s\n"
                  "params %s\n"
                  "dir-source %s %s %s %s %d %d\n"
                  "contact %s\n",
@@ -169,6 +172,7 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
                  v3_ns->vote_seconds, v3_ns->dist_seconds,
                  version_lines,
                  flags,
+                 flag_thresholds,
                  params,
                  voter->nickname, fingerprint, voter->address,
                  fmt_addr32(addr), voter->dir_port, voter->or_port,
@@ -181,6 +185,7 @@ format_networkstatus_vote(crypto_pk_t *private_signing_key,
 
     tor_free(params);
     tor_free(flags);
+    tor_free(flag_thresholds);
     tor_free(methods);
     outp = status + strlen(status);
     endp = status + len;