r16279@catbus: nickm | 2007-10-30 11:14:29 -0400

 Improved skew reporting:  "You are 365 days in the duture" is more useful than "You are 525600 minutes in the future".  Also, when we get something that proves we are at least an hour in the past, tell the controller "CLOCK_SKEW MIN_SKEW=-3600" rather than just "CLOCK_SKEW"

svn:r12283

diff --git a/ChangeLog b/ChangeLog
index 1a70f16b75fdd92e83da1dada49fc851ffefcd7f..590ffc329bc17516f5deea03555ab6c7d9b67181 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -37,6 +37,12 @@ Changes in version 0.2.0.10-alpha - 2007-1?-??
       to $PREFIX/share/tor/fallback-consensus) for a consensus.  This way
       we start knowing some directory caches.
     - When we receive a consensus from the future, warn about skew.
+    - Improve skew reporting: try to give the user a better log message about
+      how skewed they are, and how much this matters.
+
+  o Minor features (controller):
+    - When reporting clock skew, and we only have a lower bound on the amount
+      of skew, amount anyway, marked as a lower bound.
 
   - Utilities:
     - Update linux-tor-prio.sh script to allow QoS based on the uid of

diff --git a/doc/TODO b/doc/TODO
index e72a2cc9989382a06e50b39b747498830c833fc4..60bf7bf704e25b6ec852b60c4ca3a80fce28325d 100644 (file)
--- a/doc/TODO
+++ b/doc/TODO
@@ -58,10 +58,10 @@ Things we'd like to do in 0.2.0.x:
         - Revised handshake.
         - Have a 'waiting_for_authentication' state.
         - Only do version negotiation if we use the normalized TLS.
-    . Skew issues:
+    o Skew issues:
       o if you load (nick says receive/set/anything) a consensus that's
         in the future, then log about skew.
-      - should change the "skew complaint" to specify in largest units
+      o should change the "skew complaint" to specify in largest units
         rather than just seconds.
     - Learn new authority IPs from consensus/certs.
     - karsten's patches

diff --git a/doc/spec/control-spec.txt b/doc/spec/control-spec.txt
index 424deea736faea1a7a2798b51163b5196fa1b7f9..cda883e119f74cbdbdcf13c1cbb00b259530b10c 100644 (file)
--- a/doc/spec/control-spec.txt
+++ b/doc/spec/control-spec.txt
@@ -1200,14 +1200,16 @@ $Id$
 
      CLOCK_SKEW
        SKEW="+" / "-" SECONDS
+       MIN_SKEW="+" / "-" SECONDS.
        SOURCE="DIRSERV:IP:Port" / "NETWORKSTATUS:IP:PORT" / "CONSENSUS"
          If "SKEW" is present, it's an estimate of how far we are from the
-         time declared in the source.  If the source is a DIRSERV, we got
-         the current time from a connection to a dirserver.  If the source is
-         a NETWORKSTATUS, we decided we're skewed because we got a v2
-         networkstatus from far in the future.  If the source is
-         CONSENSUS, we decided we're skewed because we got a networkstatus
-         consensus from the future.
+         time declared in the source.  (In other words, if we're an hour in
+         the past, the value is -3600.)  "MIN_SKEW" is present, it's a lower
+         bound.  If the source is a DIRSERV, we got the current time from a
+         connection to a dirserver.  If the source is a NETWORKSTATUS, we
+         decided we're skewed because we got a v2 networkstatus from far in
+         the future.  If the source is CONSENSUS, we decided we're skewed
+         because we got a networkstatus consensus from the future.
 
          {Controllers may want to warn the user if the skew is high, or if
          multiple skew messages appear at severity WARN.  Controllers

diff --git a/src/common/util.c b/src/common/util.c
index 27ff0c2ceb1349118b9093809d7d44efc870b8b0..8ee64f4522900a350311811c7ff0aad54dce13fc 100644 (file)
--- a/src/common/util.c
+++ b/src/common/util.c
@@ -1250,6 +1250,41 @@ parse_http_time(const char *date, struct tm *tm)
   return 0;
 }
 
+/** DOCDOC */
+int
+format_time_interval(char *out, size_t out_len, long interval)
+{
+  /* We only report seconds if there's no hours. */
+  long sec = 0, min = 0, hour = 0, day = 0;
+  if (interval < 0)
+    interval = -interval;
+
+  if (interval >= 86400) {
+    day = interval / 86400;
+    interval %= 86400;
+  }
+  if (interval >= 3600) {
+    hour = interval / 3600;
+    interval %= 3600;
+  }
+  if (interval >= 60) {
+    min = interval / 60;
+    interval %= 60;
+  }
+  sec = interval;
+
+  if (day) {
+    return tor_snprintf(out, out_len, "%ld days, %ld hours, %ld minutes",
+                        day, hour, min);
+  } else if (hour) {
+    return tor_snprintf(out, out_len, "%ld hours, %ld minutes", hour, min);
+  } else if (min) {
+    return tor_snprintf(out, out_len, "%ld minutes, %ld seconds", min, sec);
+  } else {
+    return tor_snprintf(out, out_len, "%ld seconds", sec);
+  }
+}
+
 /* =====
  * Fuzzy time
  * ===== */

diff --git a/src/common/util.h b/src/common/util.h
index 950de9bacc97dda34074cfe1e4ec2ccdd16c4657..43587af72a672b2158cc8cce48327a4c849abe77 100644 (file)
--- a/src/common/util.h
+++ b/src/common/util.h
@@ -206,6 +206,7 @@ void format_local_iso_time(char *buf, time_t t);
 void format_iso_time(char *buf, time_t t);
 int parse_iso_time(const char *buf, time_t *t);
 int parse_http_time(const char *buf, struct tm *tm);
+int format_time_interval(char *out, size_t out_len, long interval);
 /* Fuzzy time. */
 void ftime_set_maximum_sloppiness(int seconds);
 void ftime_set_estimated_skew(int seconds);

diff --git a/src/or/directory.c b/src/or/directory.c
index a780c0078655ef6d54124f96d02e3f7151c761f7..372dd27c5a13abceda2c7703cbfe57250f12f48b 100644 (file)
--- a/src/or/directory.c
+++ b/src/or/directory.c
@@ -1250,14 +1250,18 @@ connection_dir_client_reached_eof(dir_connection_t *conn)
      */
     delta = conn->_base.timestamp_lastwritten - date_header;
     if (abs(delta)>ALLOW_DIRECTORY_TIME_SKEW) {
+      char dbuf[64];
       int trusted = router_digest_is_trusted_dir(conn->identity_digest);
+      format_time_interval(dbuf, sizeof(dbuf), delta);
       log_fn(trusted ? LOG_WARN : LOG_INFO,
              LD_HTTP,
              "Received directory with skewed time (server '%s:%d'): "
-             "we are %d minutes %s, or the directory is %d minutes %s.",
+             "It seems that our clock is %s by %s, or that theirs is %s. "
+             "Tor requires an accurate clock to work: please check your time "
+             "and date settings.",
              conn->_base.address, conn->_base.port,
-             abs(delta)/60, delta>0 ? "ahead" : "behind",
-             abs(delta)/60, delta>0 ? "behind" : "ahead");
+             delta>0 ? "ahead" : "behind", dbuf,
+             delta>0 ? "behind" : "ahead");
       skewed = 1; /* don't check the recommended-versions line */
       control_event_general_status(trusted ? LOG_WARN : LOG_NOTICE,
                                "CLOCK_SKEW SKEW=%d SOURCE=DIRSERV:%s:%d",

diff --git a/src/or/networkstatus.c b/src/or/networkstatus.c
index bbcc0ff6d5cd5ef617b2f56d9c41056e54352af1..7113183112f68eee9c1df80902cddc371125f092 100644 (file)
--- a/src/or/networkstatus.c
+++ b/src/or/networkstatus.c
@@ -559,13 +559,16 @@ router_set_networkstatus_v2(const char *s, time_t arrived_at,
   format_iso_time(published, ns->published_on);
 
   if (ns->published_on > now + NETWORKSTATUS_ALLOW_SKEW) {
-    log_warn(LD_GENERAL, "Network status from %s was published in the future "
-             "(%s GMT). Check your system clock! "
+    char dbuf[64];
+    long delta = now - ns->published_on;
+    format_time_interval(dbuf, sizeof(dbuf), delta);
+    log_warn(LD_GENERAL, "Network status from %s was published %s in the "
+             "future (%s GMT). Check your time and date settings! "
              "Not caching.",
-             source_desc, published);
+             source_desc, dbuf, published);
     control_event_general_status(LOG_WARN,
-                                 "CLOCK_SKEW SOURCE=NETWORKSTATUS:%s:%d",
-                                 ns->source_address, ns->source_dirport);
+                       "CLOCK_SKEW MIN_SKEW=%ld SOURCE=NETWORKSTATUS:%s:%d",
+                       delta, ns->source_address, ns->source_dirport);
     skewed = 1;
   }
 
@@ -1329,12 +1332,17 @@ networkstatus_set_current_consensus(const char *consensus, int from_cache,
                                         current_consensus->valid_after);
 
   if (ftime_definitely_before(now, current_consensus->valid_after)) {
-    char buf[ISO_TIME_LEN+1];
-    format_iso_time(buf, current_consensus->valid_after);
-    log_warn(LD_GENERAL, "Consensus network status document was published "
-             "at some time in the future (%s GMT).  Check your time and date "
-             "settings!", buf);
-    control_event_general_status(LOG_WARN, "CLOCK_SKEW SOURCE=CONSENSUS");
+    char tbuf[ISO_TIME_LEN+1];
+    char dbuf[64];
+    long delta = now - current_consensus->valid_after;
+    format_iso_time(tbuf, current_consensus->valid_after);
+    format_time_interval(dbuf, sizeof(dbuf), delta);
+    log_warn(LD_GENERAL, "Our clock is %s behind the time published in the "
+             "consensus network status document (%s GMT).  Tor needs an "
+             "accurate clock to work correctly. Please check your time and "
+             "date settings!", dbuf, tbuf);
+    control_event_general_status(LOG_WARN,
+                    "CLOCK_SKEW MIN_SKEW=%ld SOURCE=CONSENSUS", delta);
   }
 
   router_dir_info_changed();