ike-cfg: Add helper function to determine address family of IP addresses

All configured static addresses (hostnames, ranges or subnets are not
considered) must be of the same family, otherwise AF_UNSPEC is returned.

src/libcharon/config/ike_cfg.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2012 Tobias Brunner
+ * Copyright (C) 2012-2015 Tobias Brunner
  * Copyright (C) 2005-2007 Martin Willi
  * Copyright (C) 2005 Jan Hutter
  * Hochschule fuer Technik Rapperswil
@@ -254,4 +254,15 @@ ike_cfg_t *ike_cfg_create(ike_version_t version, bool certreq, bool force_encap,
 						  char *other, u_int16_t other_port,
 						  fragmentation_t fragmentation, u_int8_t dscp);
 
+/**
+ * Determine the address family of the local or remtoe address(es).  If multiple
+ * families are configured AF_UNSPEC is returned.  %any is ignored (%any4|6 are
+ * not though).
+ *
+ * @param local				TRUE to check local addresses, FALSE for remote
+ * @return					address family of address(es) if distinct
+ */
+int ike_cfg_get_family(ike_cfg_t *this, bool local);
+
+
 #endif /** IKE_CFG_H_ @}*/