be sure to initialize IPv4 TTL to non-zero, when IPv4 mapped address …

…is used.

in6p may carry ip6_hlim == 0 if there's no IPv6 configuration.

we should revisit it from hoplimit selection point of view too - we should
differentiate between "interface TTL is 0" and "this interface is not ready"
(in terms of nd_ifinfo)

netbsd/sys/netinet/tcp_output.c

@@ -941,6 +941,12 @@ tcp_output(tp)
 #ifdef INET6
 		else if (tp->t_in6pcb) {
 			ip->ip_ttl = tp->t_in6pcb->in6p_ip6.ip6_hlim;
+			/*
+			 * XXX ip6_hlim can be 0 if there's no IPv6
+			 * configuration
+			 */
+			if (ip->ip_ttl == 0)
+				ip->ip_ttl = ip_defttl;
 			ip->ip_tos = 0;	/*XXX*/
 		}
 #endif