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[tor-commits] [tor/master] Treat routers whose IPs have changed as having been down for MTBF/routerinfo



commit bea0a31c1c859a563f065d8b868570560abc5135
Author: Nick Mathewson <nickm@xxxxxxxxxxxxxx>
Date:   Mon Nov 22 12:30:33 2010 -0500

    Treat routers whose IPs have changed as having been down for MTBF/routerinfo
    calculation purposes.
---
 changes/bug1035  |    7 +++++++
 src/or/dirserv.c |   16 +++++++++++-----
 src/or/rephist.c |   38 +++++++++++++++++++++++++++++++++++++-
 src/or/rephist.h |    3 ++-
 4 files changed, 57 insertions(+), 7 deletions(-)

diff --git a/changes/bug1035 b/changes/bug1035
new file mode 100644
index 0000000..4b62b46
--- /dev/null
+++ b/changes/bug1035
@@ -0,0 +1,7 @@
+  o Minor features (authorities)
+    - Take altered router IPs into account when determining router stability.
+      Previously, if a router changed its IP, the authorities would not
+      treat it as having any downtime for the purposes of stability
+      calculation, whereas clients would experience downtime since the
+      IP could take a while to propagate to them.  Resolves issue 1035.
+
diff --git a/src/or/dirserv.c b/src/or/dirserv.c
index 42d7d56..52e59cd 100644
--- a/src/or/dirserv.c
+++ b/src/or/dirserv.c
@@ -3108,19 +3108,25 @@ dirserv_orconn_tls_done(const char *address,
   tor_assert(address);
   tor_assert(digest_rcvd);
 
-  SMARTLIST_FOREACH(rl->routers, routerinfo_t *, ri, {
+  /* XXX023 Doing a loop like this is stupid.  We should just look up the
+   * router by digest_rcvd, and see if address, orport, and as_advertised
+   * match up. -NM */
+  SMARTLIST_FOREACH_BEGIN(rl->routers, routerinfo_t *, ri) {
     if (!strcasecmp(address, ri->address) && or_port == ri->or_port &&
         as_advertised &&
         !memcmp(ri->cache_info.identity_digest, digest_rcvd, DIGEST_LEN)) {
       /* correct digest. mark this router reachable! */
       if (!bridge_auth || ri->purpose == ROUTER_PURPOSE_BRIDGE) {
-        log_info(LD_DIRSERV, "Found router %s to be reachable. Yay.",
-                 ri->nickname);
-        rep_hist_note_router_reachable(digest_rcvd, now);
+        tor_addr_t addr, *addrp=NULL;
+        log_info(LD_DIRSERV, "Found router %s to be reachable at %s. Yay.",
+                 ri->nickname, address);
+        if (tor_addr_from_str(&addr, ri->address) != -1)
+          addrp = &addr;
+        rep_hist_note_router_reachable(digest_rcvd, addrp, now);
         ri->last_reachable = now;
       }
     }
-  });
+  } SMARTLIST_FOREACH_END(ri);
   /* FFFF Maybe we should reinstate the code that dumps routers with the same
    * addr/port but with nonmatching keys, but instead of dumping, we should
    * skip testing. */
diff --git a/src/or/rephist.c b/src/or/rephist.c
index 22b3ec5..a0c9c9f 100644
--- a/src/or/rephist.c
+++ b/src/or/rephist.c
@@ -14,6 +14,7 @@
 #include "circuitlist.h"
 #include "circuituse.h"
 #include "config.h"
+#include "networkstatus.h"
 #include "rephist.h"
 #include "router.h"
 #include "routerlist.h"
@@ -73,6 +74,10 @@ typedef struct or_history_t {
   /** If nonzero, we have been unable to connect since this time. */
   time_t down_since;
 
+  /** The address at which we most recently connected to this OR
+   * sucessfully. */
+  tor_addr_t last_reached_addr;
+
   /* === For MTBF tracking: */
   /** Weighted sum total of all times that this router has been online.
    */
@@ -119,6 +124,7 @@ get_or_history(const char* id)
     rephist_total_num++;
     hist->link_history_map = digestmap_new();
     hist->since = hist->changed = time(NULL);
+    tor_addr_make_unspec(&hist->last_reached_addr);
     digestmap_set(history_map, id, hist);
   }
   return hist;
@@ -289,14 +295,19 @@ rep_hist_note_connection_died(const char* id, time_t when)
 /** We have just decided that this router with identity digest <b>id</b> is
  * reachable, meaning we will give it a "Running" flag for the next while. */
 void
-rep_hist_note_router_reachable(const char *id, time_t when)
+rep_hist_note_router_reachable(const char *id, const tor_addr_t *at_addr,
+                               time_t when)
 {
   or_history_t *hist = get_or_history(id);
   int was_in_run = 1;
   char tbuf[ISO_TIME_LEN+1];
+  int addr_changed;
 
   tor_assert(hist);
 
+  addr_changed = at_addr &&
+    tor_addr_compare(at_addr, &hist->last_reached_addr, CMP_EXACT) != 0;
+
   if (!started_tracking_stability)
     started_tracking_stability = time(NULL);
   if (!hist->start_of_run) {
@@ -315,6 +326,29 @@ rep_hist_note_router_reachable(const char *id, time_t when)
     down_length = when - hist->start_of_downtime;
     hist->total_weighted_time += down_length;
     hist->start_of_downtime = 0;
+  } else if (addr_changed) {
+    /* If we're reachable, but the address changed, treat this as some
+     * downtime. */
+#define MIN_DOWNTIME_FOR_ADDR_CHANGE 600
+    int penalty = get_options()->TestingTorNetwork ? 240 : 3600;
+    networkstatus_t *ns;
+    tor_assert(at_addr);
+
+    if ((ns = networkstatus_get_latest_consensus())) {
+      int fresh_interval = ns->fresh_until - ns->valid_after;
+      int live_interval = ns->valid_until - ns->valid_after;
+      /* on average, a descriptor addr change takes .5 intervals to make it
+       * into a consensus, and half a liveness period to make it to
+       * clients. */
+      penalty = (fresh_interval + live_interval) / 2;
+    }
+    format_local_iso_time(tbuf, hist->start_of_run);
+    log_info(LD_HIST,"Router %s still seems Running, but its address appears "
+             "to have changed since the last time it was reachable.  I'm "
+             "going to treat it as having been down for %d seconds",
+             hex_str(id, DIGEST_LEN), penalty);
+    rep_hist_note_router_unreachable(id, when-penalty);
+    rep_hist_note_router_reachable(id, NULL, when);
   } else {
     format_local_iso_time(tbuf, hist->start_of_run);
     if (was_in_run)
@@ -324,6 +358,8 @@ rep_hist_note_router_reachable(const char *id, time_t when)
       log_info(LD_HIST,"Router %s is now Running; it was previously untracked",
                hex_str(id, DIGEST_LEN));
   }
+  if (at_addr)
+    tor_addr_copy(&hist->last_reached_addr, at_addr);
 }
 
 /** We have just decided that this router is unreachable, meaning
diff --git a/src/or/rephist.h b/src/or/rephist.h
index 8f5a34d..1ddbac4 100644
--- a/src/or/rephist.h
+++ b/src/or/rephist.h
@@ -33,7 +33,8 @@ void rep_hist_update_state(or_state_t *state);
 int rep_hist_load_state(or_state_t *state, char **err);
 void rep_history_clean(time_t before);
 
-void rep_hist_note_router_reachable(const char *id, time_t when);
+void rep_hist_note_router_reachable(const char *id, const tor_addr_t *at_addr,
+                                    time_t when);
 void rep_hist_note_router_unreachable(const char *id, time_t when);
 int rep_hist_record_mtbf_data(time_t now, int missing_means_down);
 int rep_hist_load_mtbf_data(time_t now);



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