don't set permanent failure on udp sockets, even on unexpected error

lib/isc/unix/socket.c

@@ -350,7 +350,6 @@ process_cmsg(isc_socket_t *sock, struct msghdr *msg, isc_socketevent_t *dev) {
 	UNUSED(msg);
 	UNUSED(dev);
 
-
 #ifndef ISC_NET_BSD44MSGHDR
 	return;
 
@@ -386,10 +385,14 @@ process_cmsg(isc_socket_t *sock, struct msghdr *msg, isc_socketevent_t *dev) {
 #ifdef ISC_PLATFORM_HAVEIPV6
 		if (cmsgp->cmsg_level == IPPROTO_IPV6
 		    && cmsgp->cmsg_type == IPV6_PKTINFO) {
+			isc_sockaddr_t sa;
+
 			pktinfop = (struct in6_pktinfo *)CMSG_DATA(cmsgp);
 			memcpy(&dev->pktinfo, pktinfop,
 			       sizeof(struct in6_pktinfo));
 			dev->attributes |= ISC_SOCKEVENTATTR_PKTINFO;
+			isc_sockaddr_fromin6(&sa, &dev->pktinfo.ipi6_addr, 53);
+			socket_log(sock, &sa, TRACE, "interface received on ifindex %u", dev->pktinfo.ipi6_ifindex);
 			goto next;
 		}
 #endif
@@ -506,7 +509,12 @@ build_msghdr_send(isc_socket_t *sock, isc_socketevent_t *dev,
 	if ((sock->type == isc_sockettype_udp)
 	    && ((dev->attributes & ISC_SOCKEVENTATTR_PKTINFO) != 0)) {
 		struct cmsghdr *cmsgp;
-		struct in6_pktinfo *pktinfop; 
+		struct in6_pktinfo *pktinfop;
+		isc_sockaddr_t sa;
+
+		isc_sockaddr_fromin6(&sa, &dev->pktinfo.ipi6_addr, 53);
+		socket_log(sock, &sa, TRACE, "sendto pktinfo data, ifindex %u", dev->pktinfo.ipi6_ifindex);
+
 		msg->msg_controllen = CMSG_SPACE(sizeof(struct in6_pktinfo));
 		msg->msg_control = (void *)sock->cmsg;
 
@@ -877,6 +885,7 @@ doio_send(isc_socket_t *sock, isc_socketevent_t *dev) {
 		ALWAYS_HARD(ENETUNREACH, ISC_R_NETUNREACH);
 		ALWAYS_HARD(EHOSTUNREACH, ISC_R_HOSTUNREACH);
 		ALWAYS_HARD(ENOBUFS, ISC_R_NORESOURCES);
+		ALWAYS_HARD(EADDRNOTAVAIL, ISC_R_ADDRNOTAVAIL);
 
 #undef SOFT_OR_HARD
 #undef ALWAYS_HARD
@@ -893,7 +902,8 @@ doio_send(isc_socket_t *sock, isc_socketevent_t *dev) {
 		UNEXPECTED_ERROR(__FILE__, __LINE__,
 				 "internal_send: %s",
 				 strerror(errno));
-		sock->send_result = ISC_R_UNEXPECTED;
+		if (sock->connected && sock->type == isc_sockettype_tcp)
+			sock->send_result = ISC_R_UNEXPECTED;
 		send_senddone_event(sock, &dev, ISC_R_UNEXPECTED);
 		return (DOIO_HARD);
 	}
@@ -2336,7 +2346,15 @@ isc_socket_sendto(isc_socket_t *sock, isc_region_t *region,
 
 	set_dev_address(address, sock, dev);
 	if (pktinfo != NULL) {
+		isc_sockaddr_t sa;
+
+		isc_sockaddr_fromin6(&sa, &pktinfo->ipi6_addr, 53);
+		socket_log(sock, &sa, TRACE,
+			   "pktinfo structure provided, ifindex %u",
+			   pktinfo->ipi6_ifindex);
+
 		dev->attributes |= ISC_SOCKEVENTATTR_PKTINFO;
+		dev->pktinfo.ipi6_ifindex = 0;
 		dev->pktinfo = *pktinfo;
 	}