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, 14 insertions, 0 deletions

diff --git a/src/providers/fail_over.h b/src/providers/fail_over.h
index ffcd06877..70e694fee 100644
--- a/src/providers/fail_over.h
+++ b/src/providers/fail_over.h
@@ -30,6 +30,9 @@
 
 #include "resolv/async_resolv.h"
 
+#define FO_PROTO_TCP "tcp"
+#define FO_PROTO_UDP "udp"
+
 /* Some forward declarations that don't have to do anything with fail over. */
 struct hostent;
 struct tevent_context;
@@ -60,10 +63,14 @@ struct fo_server;
  * duration in seconds of how long a server or port will be considered
  * non-working after being marked as such.
  *
+ * The 'srv_retry_timeout' member specifies how long a SRV lookup
+ * is considered valid until we ask the server again.
+ *
  * The family_order member specifies the order of address families to
  * try when looking up the service.
  */
 struct fo_options {
+    time_t srv_retry_timeout;
     time_t retry_timeout;
     enum restrict_family family_order;
 };
@@ -101,6 +108,13 @@ int fo_add_server(struct fo_service *service,
                   int port,
                   void *user_data);
 
+
+int fo_add_srv_server(struct fo_service *service,
+                      const char *srv,
+                      const char *domain,
+                      const char *proto,
+                      void *user_data);
+
 /*
  * Request the first server from the service's list of servers. It is only
  * considered if it is not marked as not working (or the retry interval already