IPv6: in46_addr: OSMO_ASSERT() in case of unsupported calls

There's a bit of trickery with the ip_pool and it's "lengty=8" IPv6
prefix handling, let's make sure we don't accidentially call any
support functions with addresses of wrong length.

Change-Id: I444c190bdcd18780344e1f0dad4faf3bcf9da5a5
diff --git a/lib/in46_addr.c b/lib/in46_addr.c
index 1785377..8f5cc09 100644
--- a/lib/in46_addr.c
+++ b/lib/in46_addr.c
@@ -11,6 +11,8 @@
 
 #include "../lib/in46_addr.h"
 
+#include <osmocom/core/utils.h>
+
 #include <sys/types.h>
 #include <netinet/in.h>
 #include <sys/socket.h>
@@ -29,6 +31,7 @@
 	case 16:
 		return AF_INET6;
 	default:
+		OSMO_ASSERT(0);
 		return -1;
 	}
 }
@@ -49,6 +52,7 @@
 		sin6->sin6_addr = in->v6;
 		break;
 	default:
+		OSMO_ASSERT(0);
 		return -1;
 	}
 
@@ -161,6 +165,7 @@
 		create_ipv6_netmask(&netmask6, prefixlen);
 		return ipv6_within_mask(&addr->v6, &net->v6, &netmask6);
 	default:
+		OSMO_ASSERT(0);
 		return 0;
 	}
 }
@@ -184,6 +189,7 @@
 		memcpy(&eua->v[2], &src->v6, 16);	/* Copy a 16 byte address */
 		break;
 	default:
+		OSMO_ASSERT(0);
 		return -1;
 	}
 	return 0;