Use observed instead of declared uptime for HSDir

It is important to verify the uptime claim of a relay instead of just
trusting it, otherwise it becomes too easy to blackhole a specific
hidden service. rephist already has data available that we can use here.

Bugfix on 0.2.0.10-alpha.

1 files changed, 14 insertions, 0 deletions

diff --git a/src/or/rephist.c b/src/or/rephist.c
index 53214d61ef..69001de839 100644
--- a/src/or/rephist.c
+++ b/src/or/rephist.c
@@ -528,6 +528,20 @@ get_weighted_fractional_uptime(or_history_t *hist, time_t when)
   return ((double) up) / total;
 }
 
+/** Return how long the router whose identity digest is <b>id</b> has
+ *  been reachable. Return 0 if the router is unknown or currently deemed
+ *  unreachable. */
+long
+rep_hist_get_uptime(const char *id, time_t when)
+{
+  or_history_t *hist = get_or_history(id);
+  if (!hist)
+    return 0;
+  if (!hist->start_of_run)
+    return 0;
+  return when - hist->start_of_run;
+}
+
 /** Return an estimated MTBF for the router whose identity digest is
  * <b>id</b>. Return 0 if the router is unknown. */
 double