more cname-skip unit-tests and simplification of skip-finder function

[pingcheck] / src / dns / dnscache.cpp

diff --git a/src/dns/dnscache.cpp b/src/dns/dnscache.cpp
index 4b8df17..4ad62c4 100644 (file)
--- a/src/dns/dnscache.cpp
+++ b/src/dns/dnscache.cpp
@@ -362,16 +362,12 @@ HostAddressVec DnsCache::get_ips_recursive(const std::string &hostname,
 }
 
 /**
- * from a list of CNAMEs find the first one that is out of date
+ * from a list of CNAMEs find the first one that is out of date or empty
+ *
+ * returns the hostname that is out of date or empty if all CNAMEs are
+ *   up-to-date
  *
  * required in ResolverBase::get_skipper
- * 
- * Assume you have the following situation in cache with TTLs below:
- * hostname --> cname1 --> cname2 --> ... --> cnameN [--> IP]
- *               100         0                                --> return cname2
- *               100        100        100     100            --> return cnameN
- *    ( with N < Config::MaxRetrievalRecursions )
- * hostname --> IP (no cnames involved) --> return hostname
  */
 std::string DnsCache::get_first_outdated_cname(const std::string &hostname,
                                                const uint32_t ttl_thresh)
@@ -385,23 +381,23 @@ std::string DnsCache::get_first_outdated_cname(const std::string &hostname,
         {
             GlobalLogger.warning() << "DnsCache: reached recursion limit of "
                 << n_recursions << " in search of outdated CNAMEs!";
-            break;
-        }
+            return first_outdated;   // not really out of date but currently
+        }                            // our best guess
 
         cname = get_cname(first_outdated);
         if (cname.Host.empty())
-            // reached end of cname list
-            break;
+            // reached end of cname list --> everything was up-to-date
+            return "";
         else if (cname.Ttl.get_updated_value() > ttl_thresh)
             // cname is up to date --> continue looking
             first_outdated = cname.Host;
         else
-        {   // cname is out of date --> return its target
-            first_outdated = cname.Host;
-            break;
-        }
+            // cname is out of date --> return its target
+            return cname.Host;
     }
-    return first_outdated;
+    // reach this point only if cname chain does not end with an IP
+    // --> all are up-to-date
+    return "";
 }
 
 // (created using vim -- the world's best text editor)