Change: Don't perform alive tests if "consider alive" method is selec…

…ted (#798)

When more than one alive test method is selected, boreas check for
each one until the host is alive.
This will be done also even if the "consider alive" methods is selected.

This patch improves boreas to not run other selected alive methods
if "consider alive" method is set and there are no scan restrictions.

In case of scan restrictions (max_scan_host preference), this will not apply
to not fill the limited slots with probably dead hosts.

boreas/alivedetection.c

@@ -76,6 +76,29 @@ scan (alive_test_t alive_test)
   g_message ("Alive scan %s started: Target has %d hosts", scan_id,
              number_of_targets);
 
+  /* Check first if consider alive test method is set. In case that
+   * there is no scan restrictions, no other test will be performed, because
+   * it doesn't make sense.
+   * Otherwise, if a scan restriction is set (the max_scan_hosts feature),
+   * the other selected methods must be performed first to fill a list with
+   * alive hosts and not only with the first which we don't now if they are dead
+   * or alive. This will ensure that restricted users will get the max possible
+   * amount of alive hosts before starting to fill the list with dead hosts.
+   */
+  if (alive_test & ALIVE_TEST_CONSIDER_ALIVE
+      && scanner.scan_restrictions->max_scan_hosts == 0)
+    {
+      g_debug ("%s: Consider Alive", __func__);
+      for (g_hash_table_iter_init (&target_hosts_iter,
+                                   scanner.hosts_data->targethosts);
+           g_hash_table_iter_next (&target_hosts_iter, &key, &value);)
+        {
+          g_hash_table_add (scanner.hosts_data->alivehosts, g_strdup (key));
+          handle_scan_restrictions (&scanner, key);
+        }
+      goto finish_alive_test;
+    }
+
   /* Sniffer thread needed if any alive test besides ALIVE_TEST_CONSIDER_ALIVE
    * was chosen. */
   if (alive_test != ALIVE_TEST_CONSIDER_ALIVE)
@@ -226,6 +249,7 @@ scan (alive_test_t alive_test)
       stop_sniffer_thread (&scanner, sniffer_thread_id);
     }
 
+finish_alive_test:
   /* If only ICMP was specified we continuously send updates about dead hosts to
    * ospd while checking the hosts. We now only have to send the dead hosts of
    * the last batch. This is done here to catch the last alive hosts which may

boreas/boreas_io.c

@@ -474,6 +474,7 @@ get_alive_test_methods (alive_test_t *alive_test)
     {
       *alive_test = atoi (alive_test_pref_as_str);
     }
+
   return error;
 }