Make dirservers generate a separate "guard" flag to mean, "would make a good entry guard". Make clients parse it and vote on it.

svn:r5856

src/or/dirserv.c

@@ -1422,6 +1422,7 @@ generate_v2_networkstatus(void)
                                       ri->cache_info.identity_digest);
       int f_named = naming && ri->is_named;
       int f_valid = ri->is_verified;
+      int f_guard = f_fast && f_stable;
       /* 0.1.1.9-alpha is the first version to support fetch by descriptor
        * hash. */
       int f_v2_dir = ri->dir_port &&
@@ -1450,6 +1451,7 @@ generate_v2_networkstatus(void)
                        f_authority?" Authority":"",
                        f_exit?" Exit":"",
                        f_fast?" Fast":"",
+                       f_guard?" Guard":"",
                        f_named?" Named":"",
                        f_stable?" Stable":"",
                        f_running?" Running":"",

src/or/or.h

@@ -844,6 +844,8 @@ typedef struct routerstatus_t {
                              * information with v2 of the directory
                              * protocol. (All directory caches cache v1
                              * directories.)  */
+  unsigned int is_possible_guard:1; /**< True iff this router would be a good
+                                     * choice as an entry guard. */
 
   /** True if we, as a directory mirror, want to download the corresponding
    * routerinfo from the authority who gave us this routerstatus.  (That is,

src/or/routerlist.c

@@ -2941,7 +2941,7 @@ routerstatus_list_update_from_networkstatus(time_t now)
    */
   while (1) {
     int n_running=0, n_named=0, n_valid=0, n_listing=0;
-    int n_v2_dir=0, n_fast=0, n_stable=0, n_exit=0;
+    int n_v2_dir=0, n_fast=0, n_stable=0, n_exit=0, n_guard=0;
     int n_desc_digests=0, highest_count=0;
     const char *the_name = NULL;
     local_routerstatus_t *rs_out, *rs_old;
@@ -3020,6 +3020,8 @@ routerstatus_list_update_from_networkstatus(time_t now)
         ++n_exit;
       if (rs->is_fast)
         ++n_fast;
+      if (rs->is_possible_guard)
+        ++n_guard;
       if (rs->is_stable)
         ++n_stable;
       if (rs->is_v2_dir)
@@ -3069,6 +3071,7 @@ routerstatus_list_update_from_networkstatus(time_t now)
     rs_out->status.is_running = n_running > n_recent/2;
     rs_out->status.is_exit = n_exit > n_statuses/2;
     rs_out->status.is_fast = n_fast > n_statuses/2;
+    rs_out->status.is_fast = n_guard > n_statuses/2;
     rs_out->status.is_stable = n_stable > n_statuses/2;
     rs_out->status.is_v2_dir = n_v2_dir > n_statuses/2;
   }

src/or/routerparse.c

@@ -1037,6 +1037,8 @@ routerstatus_parse_entry_from_string(const char **s, smartlist_t *tokens)
         rs->is_valid = 1;
       else if (!strcmp(tok->args[i], "V2Dir"))
         rs->is_v2_dir = 1;
+      else if (!strcmp(tok->args[i], "Guard"))
+        rs->is_possible_guard = 1;
     }
   }