Merge branch 'bug1074_launch_conn_on_skew'

Fixed conflict on rename of router_get_by_digest->router_get_by_id_digest

Conflicts:
	src/or/command.c

changes/launch_authcon_on_skew

@@ -0,0 +1,7 @@
+  o Minor features
+    - When we get a connection from a non-authority that tells us our
+      clock is skewed, and we haven't heard about clock skew (or lack
+      thereof) from an authority, launch a connection to an authority
+      so we can find out whether we're really skewed.  Related to
+      bug 1074.  Patch from "AltF4".
+

src/or/command.c

@@ -45,6 +45,13 @@ uint64_t stats_n_destroy_cells_processed = 0;
 uint64_t stats_n_versions_cells_processed = 0;
 /** How many CELL_NETINFO cells have we received, ever? */
 uint64_t stats_n_netinfo_cells_processed = 0;
+/** Have we received a NETINFO cell from a trusted dir, ever? Used
+ * to decide what to do about time skew.
+ * 0 == No, and and we haven't tried asking an authority yet
+ * 1 == No, we've launched a query but haven't heard back yet
+ * 2 == Yes
+ **/
+static int received_netinfo_from_trusted_dir = 0;
 
 /* These are the main functions for processing cells */
 static void command_process_create_cell(cell_t *cell, or_connection_t *conn);
@@ -621,17 +628,16 @@ command_process_netinfo_cell(cell_t *cell, or_connection_t *conn)
   }
 
   /* Act on apparent skew. */
-  /** Warn when we get a netinfo skew with at least this value. */
+  /** Warn when we get a netinfo skew with at least this value.
+      Ignore if we've already received skew info from a trusted dir */
 #define NETINFO_NOTICE_SKEW 3600
   if (labs(apparent_skew) > NETINFO_NOTICE_SKEW &&
-      router_get_by_id_digest(conn->identity_digest)) {
+      router_get_by_id_digest(conn->identity_digest) &&
+      received_netinfo_from_trusted_dir != 2) {
     char dbuf[64];
-    int severity;
+
-    /*XXXX be smarter about when everybody says we are skewed. */
+    int severity = router_digest_is_trusted_dir(conn->identity_digest) ?
-    if (router_digest_is_trusted_dir(conn->identity_digest))
+                   LOG_WARN : LOG_INFO;
-      severity = LOG_WARN;
-    else
-      severity = LOG_INFO;
     format_time_interval(dbuf, sizeof(dbuf), apparent_skew);
     log_fn(severity, LD_GENERAL, "Received NETINFO cell with skewed time from "
            "server at %s:%d.  It seems that our clock is %s by %s, or "
@@ -640,12 +646,30 @@ command_process_netinfo_cell(cell_t *cell, or_connection_t *conn)
            conn->_base.address, (int)conn->_base.port,
            apparent_skew>0 ? "ahead" : "behind", dbuf,
            apparent_skew>0 ? "behind" : "ahead");
-    if (severity == LOG_WARN) /* only tell the controller if an authority */
+    if (severity == LOG_WARN) { /* only tell the controller if an authority */
       control_event_general_status(LOG_WARN,
                           "CLOCK_SKEW SKEW=%ld SOURCE=OR:%s:%d",
                           apparent_skew,
                           conn->_base.address, conn->_base.port);
+      received_netinfo_from_trusted_dir = 2;
+    /* Connect to a trusted dir to trigger a NETINFO cell
+     * only if we haven't already */
+    } else if (received_netinfo_from_trusted_dir == 0) {
+      routerstatus_t *any_trusted_dir =
+        router_pick_trusteddirserver(NO_AUTHORITY, 0);
+      tor_addr_t trusted_dir_addr;
+      tor_addr_from_ipv4h(&trusted_dir_addr, any_trusted_dir->addr);
+      connection_or_connect(&trusted_dir_addr,
+        any_trusted_dir->or_port,
+        any_trusted_dir->identity_digest);
+      received_netinfo_from_trusted_dir = 1;
     }
+  }
+
+  /* Note that we received a good netinfo cell from a trusted directory */
+  if (router_digest_is_trusted_dir(conn->identity_digest) &&
+      labs(apparent_skew) <= NETINFO_NOTICE_SKEW)
+    received_netinfo_from_trusted_dir = 2;
 
   /* XXX maybe act on my_apparent_addr, if the source is sufficiently
    * trustworthy. */