Support SRV servers in failover

Adds a new failover API call fo_add_srv_server that allows the caller
to specify a server that is later resolved into a list of specific
servers using SRV requests.

Also adds a new failover option that specifies how often should the
servers resolved from SRV query considered valid until we need a
refresh.

The "real" servers to connect to are returned to the user as usual,
using the fo_resolve_service_{send,recv} calls.

Make SRV resolution work with c-ares 1.6

1 files changed, 16 insertions, 0 deletions

diff --git a/src/util/dlinklist.h b/src/util/dlinklist.h
index be5ff914..f323de70 100644
--- a/src/util/dlinklist.h
+++ b/src/util/dlinklist.h
@@ -110,6 +110,22 @@ do { \
 		} \
 } while (0)
 
+/* insert all elements from list2 after the given element 'el' in the
+ * first list */
+#define DLIST_ADD_LIST_AFTER(list1, el, list2, type) \
+do { \
+                if (!(list1) || !(el) || !(list2)) { \
+                    DLIST_CONCATENATE(list1, list2, type); \
+                } else { \
+                    type tmp; \
+                    for (tmp = (list2); tmp->next; tmp = tmp->next) ; \
+                    (list2)->prev = (el); \
+                    tmp->next = (el)->next; \
+                    (el)->next = (list2); \
+                    if ((el)->next != NULL) (el)->next->prev = tmp; \
+    } \
+} while (0);
+
 #define DLIST_FOR_EACH(p, list) \
 	for ((p) = (list); (p) != NULL; (p) = (p)->next)