+static gboolean cache_invalidate_entry(gpointer key, gpointer value,
+ gpointer user_data)
+{
+ struct cache_entry *entry = value;
+
+ /* first, delete any expired elements */
+ cache_enforce_validity(entry);
+
+ /* if anything is not expired, mark the entry for refresh */
+ if (entry->hits > 0 && (entry->ipv4 || entry->ipv6))
+ entry->want_refresh = 1;
+
+ /* delete the cached data */
+ if (entry->ipv4) {
+ g_free(entry->ipv4->data);
+ g_free(entry->ipv4);
+ entry->ipv4 = NULL;
+ }
+
+ if (entry->ipv6) {
+ g_free(entry->ipv6->data);
+ g_free(entry->ipv6);
+ entry->ipv6 = NULL;
+ }
+
+ /* keep the entry if we want it refreshed, delete it otherwise */
+ if (entry->want_refresh)
+ return FALSE;
+ else
+ return TRUE;
+}
+
+/*
+ * cache_invalidate is called from places where the DNS landscape
+ * has changed, say because connections are added or we entered a VPN.
+ * The logic is to wipe all cache data, but mark all non-expired
+ * parts of the cache for refresh rather than deleting the whole cache.
+ */
+static void cache_invalidate(void)
+{
+ DBG("Invalidating the DNS cache %p", cache);
+
+ if (cache == NULL)
+ return;
+
+ g_hash_table_foreach_remove(cache, cache_invalidate_entry, NULL);
+}
+
+static void cache_refresh_entry(struct cache_entry *entry)
+{
+
+ cache_enforce_validity(entry);
+
+ if (entry->hits > 2 && entry->ipv4 == NULL)
+ entry->want_refresh = 1;
+ if (entry->hits > 2 && entry->ipv6 == NULL)
+ entry->want_refresh = 1;
+
+ if (entry->want_refresh) {
+ char *c;
+ char dns_name[NS_MAXDNAME + 1];
+ entry->want_refresh = 0;
+
+ /* turn a DNS name into a hostname with dots */
+ strncpy(dns_name, entry->key, NS_MAXDNAME);
+ c = dns_name;
+ while (c && *c) {
+ int jump;
+ jump = *c;
+ *c = '.';
+ c += jump + 1;
+ }
+ DBG("Refreshing %s\n", dns_name);
+ /* then refresh the hostname */
+ refresh_dns_entry(entry, &dns_name[1]);
+ }
+}
+
+static void cache_refresh_iterator(gpointer key, gpointer value,
+ gpointer user_data)
+{
+ struct cache_entry *entry = value;
+
+ cache_refresh_entry(entry);
+}
+
+static void cache_refresh(void)
+{
+ if (cache == NULL)
+ return;
+
+ g_hash_table_foreach(cache, cache_refresh_iterator, NULL);
+}
+