+
+uint32_t manager_find_mtu(Manager *m) {
+ uint32_t mtu = 0;
+ Link *l;
+ Iterator i;
+
+ /* If we don't know on which link a DNS packet would be
+ * delivered, let's find the largest MTU that works on all
+ * interfaces we know of */
+
+ HASHMAP_FOREACH(l, m->links, i) {
+ if (l->mtu <= 0)
+ continue;
+
+ if (mtu <= 0 || l->mtu < mtu)
+ mtu = l->mtu;
+ }
+
+ return mtu;
+}
+
+static int on_llmnr_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
+ _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
+ DnsQueryTransaction *t = NULL;
+ Manager *m = userdata;
+ int r;
+
+ r = manager_recv(m, fd, DNS_PROTOCOL_LLMNR, &p);
+ if (r <= 0)
+ return r;
+
+ if (dns_packet_validate_reply(p) >= 0) {
+ t = hashmap_get(m->dns_query_transactions, UINT_TO_PTR(DNS_PACKET_ID(p)));
+ if (!t)
+ return 0;
+
+ dns_query_transaction_process_reply(t, p);
+ }
+
+ return 0;
+}
+
+int manager_llmnr_ipv4_udp_fd(Manager *m) {
+ union sockaddr_union sa = {
+ .in.sin_family = AF_INET,
+ .in.sin_port = htobe16(5355),
+ };
+ static const int one = 1, pmtu = IP_PMTUDISC_DONT;
+ int r;
+
+ assert(m);
+
+ if (m->llmnr_ipv4_udp_fd >= 0)
+ return m->llmnr_ipv4_udp_fd;
+
+ m->llmnr_ipv4_udp_fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
+ if (m->llmnr_ipv4_udp_fd < 0)
+ return -errno;
+
+ r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_TTL, &one, sizeof(one));
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_TTL, &one, sizeof(one));
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_LOOP, &one, sizeof(one));
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = setsockopt(m->llmnr_ipv4_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one));
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ /* Disable Don't-Fragment bit in the IP header */
+ r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MTU_DISCOVER, &pmtu, sizeof(pmtu));
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = bind(m->llmnr_ipv4_udp_fd, &sa.sa, sizeof(sa.in));
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = sd_event_add_io(m->event, &m->llmnr_ipv4_udp_event_source, m->llmnr_ipv4_udp_fd, EPOLLIN, on_llmnr_packet, m);
+ if (r < 0)
+ goto fail;
+
+ return m->llmnr_ipv4_udp_fd;
+
+fail:
+ m->llmnr_ipv4_udp_fd = safe_close(m->llmnr_ipv4_udp_fd);
+ return r;
+}
+
+int manager_llmnr_ipv6_udp_fd(Manager *m) {
+ union sockaddr_union sa = {
+ .in6.sin6_family = AF_INET6,
+ .in6.sin6_port = htobe16(5355),
+ };
+ static const int one = 1;
+ int r;
+
+ assert(m);
+
+ if (m->llmnr_ipv6_udp_fd >= 0)
+ return m->llmnr_ipv6_udp_fd;
+
+ m->llmnr_ipv6_udp_fd = socket(AF_INET6, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
+ if (m->llmnr_ipv6_udp_fd < 0)
+ return -errno;
+
+ r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &one, sizeof(one));
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &one, sizeof(one));
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &one, sizeof(one));
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = setsockopt(m->llmnr_ipv6_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = bind(m->llmnr_ipv6_udp_fd, &sa.sa, sizeof(sa.in6));
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = sd_event_add_io(m->event, &m->llmnr_ipv6_udp_event_source, m->llmnr_ipv6_udp_fd, EPOLLIN, on_llmnr_packet, m);
+ if (r < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ return m->llmnr_ipv6_udp_fd;
+
+fail:
+ m->llmnr_ipv6_udp_fd = safe_close(m->llmnr_ipv6_udp_fd);
+ return r;
+}