IPv6 support for user IP

This patch enables the use of IPv6 PDP contexts.  The phone will
have to request an IPv6 End-user-Address, and the GGSN will have
to be configured for an IPv6 pool.

The outer transport-layer IP between SGSN and GGSN must still be
IPv4, it is not modified by this patch

Change-Id: I22c3bf32a98e5daf99d6eaeac8c9f95cc7574774
diff --git a/lib/in46_addr.h b/lib/in46_addr.h
index f28fd8e..a0ad6e1 100644
--- a/lib/in46_addr.h
+++ b/lib/in46_addr.h
@@ -2,6 +2,8 @@
 #include <stdint.h>
 #include <netinet/in.h>
 
+#include "../gtp/pdp.h"
+
 /* a simple wrapper around an in6_addr to also contain the length of the address,
  * thereby implicitly indicating the address family of the address */
 struct in46_addr {
@@ -17,3 +19,6 @@
 extern const char *in46a_ntop(const struct in46_addr *in, char *dst, socklen_t dst_size);
 extern int in46a_equal(const struct in46_addr *a, const struct in46_addr *b);
 extern int in46a_within_mask(const struct in46_addr *addr, const struct in46_addr *net, size_t prefixlen);
+
+int in46a_to_eua(const struct in46_addr *src, struct ul66_t *eua);
+int in46a_from_eua(const struct ul66_t *eua, struct in46_addr *dst);