4 This file is part of avahi.
6 avahi is free software; you can redistribute it and/or modify it
7 under the terms of the GNU Lesser General Public License as
8 published by the Free Software Foundation; either version 2.1 of the
9 License, or (at your option) any later version.
11 avahi is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
14 Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with avahi; if not, write to the Free Software
18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
33 #include <sys/ioctl.h>
36 #include <sys/types.h>
37 #include <sys/socket.h>
38 #include <netinet/in.h>
39 #include <arpa/inet.h>
44 #include <net/if_dl.h>
51 #include "addr-util.h"
53 /* this is a portability hack */
54 #ifndef IPV6_ADD_MEMBERSHIP
55 #ifdef IPV6_JOIN_GROUP
56 #define IPV6_ADD_MEMBERSHIP IPV6_JOIN_GROUP
60 #ifndef IPV6_DROP_MEMBERSHIP
61 #ifdef IPV6_LEAVE_GROUP
62 #define IPV6_DROP_MEMBERSHIP IPV6_LEAVE_GROUP
66 static void mdns_mcast_group_ipv4(struct sockaddr_in *ret_sa) {
69 memset(ret_sa, 0, sizeof(struct sockaddr_in));
70 ret_sa->sin_family = AF_INET;
71 ret_sa->sin_port = htons(AVAHI_MDNS_PORT);
72 inet_pton(AF_INET, AVAHI_IPV4_MCAST_GROUP, &ret_sa->sin_addr);
75 static void mdns_mcast_group_ipv6(struct sockaddr_in6 *ret_sa) {
78 memset(ret_sa, 0, sizeof(struct sockaddr_in6));
79 ret_sa->sin6_family = AF_INET6;
80 ret_sa->sin6_port = htons(AVAHI_MDNS_PORT);
81 inet_pton(AF_INET6, AVAHI_IPV6_MCAST_GROUP, &ret_sa->sin6_addr);
84 static void ipv4_address_to_sockaddr(struct sockaddr_in *ret_sa, const AvahiIPv4Address *a, uint16_t port) {
89 memset(ret_sa, 0, sizeof(struct sockaddr_in));
90 ret_sa->sin_family = AF_INET;
91 ret_sa->sin_port = htons(port);
92 memcpy(&ret_sa->sin_addr, a, sizeof(AvahiIPv4Address));
95 static void ipv6_address_to_sockaddr(struct sockaddr_in6 *ret_sa, const AvahiIPv6Address *a, uint16_t port) {
100 memset(ret_sa, 0, sizeof(struct sockaddr_in6));
101 ret_sa->sin6_family = AF_INET6;
102 ret_sa->sin6_port = htons(port);
103 memcpy(&ret_sa->sin6_addr, a, sizeof(AvahiIPv6Address));
106 int avahi_mdns_mcast_join_ipv4(int fd, const AvahiIPv4Address *a, int idx, int join) {
107 #ifdef HAVE_STRUCT_IP_MREQN
108 struct ip_mreqn mreq;
112 struct sockaddr_in sa;
118 memset(&mreq, 0, sizeof(mreq));
119 #ifdef HAVE_STRUCT_IP_MREQN
120 mreq.imr_ifindex = idx;
121 mreq.imr_address.s_addr = a->address;
123 mreq.imr_interface.s_addr = a->address;
125 mdns_mcast_group_ipv4(&sa);
126 mreq.imr_multiaddr = sa.sin_addr;
129 setsockopt(fd, IPPROTO_IP, IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq));
131 if (setsockopt(fd, IPPROTO_IP, join ? IP_ADD_MEMBERSHIP : IP_DROP_MEMBERSHIP, &mreq, sizeof(mreq)) < 0) {
132 avahi_log_warn("%s failed: %s", join ? "IP_ADD_MEMBERSHIP" : "IP_DROP_MEMBERSHIP", strerror(errno));
139 int avahi_mdns_mcast_join_ipv6(int fd, const AvahiIPv6Address *a, int idx, int join) {
140 struct ipv6_mreq mreq6;
141 struct sockaddr_in6 sa6;
147 memset(&mreq6, 0, sizeof(mreq6));
148 mdns_mcast_group_ipv6 (&sa6);
149 mreq6.ipv6mr_multiaddr = sa6.sin6_addr;
150 mreq6.ipv6mr_interface = idx;
152 if (setsockopt(fd, IPPROTO_IPV6, join ? IPV6_ADD_MEMBERSHIP : IPV6_DROP_MEMBERSHIP, &mreq6, sizeof(mreq6)) < 0) {
153 avahi_log_warn("%s failed: %s", join ? "IPV6_ADD_MEMBERSHIP" : "IPV6_DROP_MEMBERSHIP", strerror(errno));
160 static int reuseaddr(int fd) {
164 if (setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &yes, sizeof(yes)) < 0) {
165 avahi_log_warn("SO_REUSEADDR failed: %s", strerror(errno));
171 if (setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &yes, sizeof(yes)) < 0) {
172 avahi_log_warn("SO_REUSEPORT failed: %s", strerror(errno));
180 static int bind_with_warn(int fd, const struct sockaddr *sa, socklen_t l) {
186 if (bind(fd, sa, l) < 0) {
188 if (errno != EADDRINUSE) {
189 avahi_log_warn("bind() failed: %s", strerror(errno));
193 avahi_log_warn("*** WARNING: Detected another %s mDNS stack running on this host. This makes mDNS unreliable and is thus not recommended. ***",
194 sa->sa_family == AF_INET ? "IPv4" : "IPv6");
196 /* Try again, this time with SO_REUSEADDR set */
197 if (reuseaddr(fd) < 0)
200 if (bind(fd, sa, l) < 0) {
201 avahi_log_warn("bind() failed: %s", strerror(errno));
206 /* We enable SO_REUSEADDR afterwards, to make sure that the
207 * user may run other mDNS implementations if he really
210 if (reuseaddr(fd) < 0)
217 static int ipv4_pktinfo(int fd) {
222 if (setsockopt(fd, IPPROTO_IP, IP_PKTINFO, &yes, sizeof(yes)) < 0) {
223 avahi_log_warn("IP_PKTINFO failed: %s", strerror(errno));
228 #ifdef IP_RECVINTERFACE
230 if (setsockopt (fd, IPPROTO_IP, IP_RECVINTERFACE, &yes, sizeof(yes)) < 0) {
231 avahi_log_warn("IP_RECVINTERFACE failed: %s", strerror(errno));
234 #elif defined(IP_RECVIF)
236 if (setsockopt (fd, IPPROTO_IP, IP_RECVIF, &yes, sizeof(yes)) < 0) {
237 avahi_log_warn("IP_RECVIF failed: %s", strerror(errno));
242 #ifdef IP_RECVDSTADDR
244 if (setsockopt (fd, IPPROTO_IP, IP_RECVDSTADDR, &yes, sizeof(yes)) < 0) {
245 avahi_log_warn("IP_RECVDSTADDR failed: %s", strerror(errno));
250 #endif /* IP_PKTINFO */
254 if (setsockopt(fd, IPPROTO_IP, IP_RECVTTL, &yes, sizeof(yes)) < 0) {
255 avahi_log_warn("IP_RECVTTL failed: %s", strerror(errno));
263 static int ipv6_pktinfo(int fd) {
266 #ifdef IPV6_RECVPKTINFO
268 if (setsockopt(fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &yes, sizeof(yes)) < 0) {
269 avahi_log_warn("IPV6_RECVPKTINFO failed: %s", strerror(errno));
272 #elif defined(IPV6_PKTINFO)
274 if (setsockopt(fd, IPPROTO_IPV6, IPV6_PKTINFO, &yes, sizeof(yes)) < 0) {
275 avahi_log_warn("IPV6_PKTINFO failed: %s", strerror(errno));
282 if (setsockopt(fd, IPPROTO_IPV6, IPV6_RECVHOPS, &yes, sizeof(yes)) < 0) {
283 avahi_log_warn("IPV6_RECVHOPS failed: %s", strerror(errno));
286 #elif defined(IPV6_RECVHOPLIMIT)
288 if (setsockopt(fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &yes, sizeof(yes)) < 0) {
289 avahi_log_warn("IPV6_RECVHOPLIMIT failed: %s", strerror(errno));
292 #elif defined(IPV6_HOPLIMIT)
294 if (setsockopt(fd, IPPROTO_IPV6, IPV6_HOPLIMIT, &yes, sizeof(yes)) < 0) {
295 avahi_log_warn("IPV6_HOPLIMIT failed: %s", strerror(errno));
303 int avahi_open_socket_ipv4(int no_reuse) {
304 struct sockaddr_in local;
305 int fd = -1, r, ittl;
308 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
309 avahi_log_warn("socket() failed: %s", strerror(errno));
314 if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)) < 0) {
315 avahi_log_warn("IP_MULTICAST_TTL failed: %s", strerror(errno));
320 if (setsockopt(fd, IPPROTO_IP, IP_TTL, &ittl, sizeof(ittl)) < 0) {
321 avahi_log_warn("IP_TTL failed: %s", strerror(errno));
326 if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_LOOP, &cyes, sizeof(cyes)) < 0) {
327 avahi_log_warn("IP_MULTICAST_LOOP failed: %s", strerror(errno));
331 memset(&local, 0, sizeof(local));
332 local.sin_family = AF_INET;
333 local.sin_port = htons(AVAHI_MDNS_PORT);
336 r = bind(fd, (struct sockaddr*) &local, sizeof(local));
338 r = bind_with_warn(fd, (struct sockaddr*) &local, sizeof(local));
343 if (ipv4_pktinfo (fd) < 0)
346 if (avahi_set_cloexec(fd) < 0) {
347 avahi_log_warn("FD_CLOEXEC failed: %s", strerror(errno));
351 if (avahi_set_nonblock(fd) < 0) {
352 avahi_log_warn("O_NONBLOCK failed: %s", strerror(errno));
365 int avahi_open_socket_ipv6(int no_reuse) {
366 struct sockaddr_in6 sa, local;
370 mdns_mcast_group_ipv6(&sa);
372 if ((fd = socket(AF_INET6, SOCK_DGRAM, 0)) < 0) {
373 avahi_log_warn("socket() failed: %s", strerror(errno));
378 if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl)) < 0) {
379 avahi_log_warn("IPV6_MULTICAST_HOPS failed: %s", strerror(errno));
384 if (setsockopt(fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl)) < 0) {
385 avahi_log_warn("IPV6_UNICAST_HOPS failed: %s", strerror(errno));
390 if (setsockopt(fd, IPPROTO_IPV6, IPV6_V6ONLY, &yes, sizeof(yes)) < 0) {
391 avahi_log_warn("IPV6_V6ONLY failed: %s", strerror(errno));
396 if (setsockopt(fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &yes, sizeof(yes)) < 0) {
397 avahi_log_warn("IPV6_MULTICAST_LOOP failed: %s", strerror(errno));
401 memset(&local, 0, sizeof(local));
402 local.sin6_family = AF_INET6;
403 local.sin6_port = htons(AVAHI_MDNS_PORT);
406 r = bind(fd, (struct sockaddr*) &local, sizeof(local));
408 r = bind_with_warn(fd, (struct sockaddr*) &local, sizeof(local));
413 if (ipv6_pktinfo(fd) < 0)
416 if (avahi_set_cloexec(fd) < 0) {
417 avahi_log_warn("FD_CLOEXEC failed: %s", strerror(errno));
421 if (avahi_set_nonblock(fd) < 0) {
422 avahi_log_warn("O_NONBLOCK failed: %s", strerror(errno));
435 static int sendmsg_loop(int fd, struct msghdr *msg, int flags) {
441 if (sendmsg(fd, msg, flags) >= 0)
444 if (errno != EAGAIN) {
445 avahi_log_debug("sendmsg() failed: %s", strerror(errno));
449 if (avahi_wait_for_write(fd) < 0)
456 int avahi_send_dns_packet_ipv4(int fd, AvahiIfIndex interface, AvahiDnsPacket *p, const AvahiIPv4Address *src_address, const AvahiIPv4Address *dst_address, uint16_t dst_port) {
457 struct sockaddr_in sa;
461 struct cmsghdr *cmsg;
462 size_t cmsg_data[( CMSG_SPACE(sizeof(struct in_pktinfo)) / sizeof(size_t)) + 1];
463 #elif defined(IP_SENDSRCADDR)
464 struct cmsghdr *cmsg;
465 size_t cmsg_data[( CMSG_SPACE(sizeof(struct in_addr)) / sizeof(size_t)) + 1];
470 assert(avahi_dns_packet_check_valid(p) >= 0);
471 assert(!dst_address || dst_port > 0);
474 mdns_mcast_group_ipv4(&sa);
476 ipv4_address_to_sockaddr(&sa, dst_address, dst_port);
478 memset(&io, 0, sizeof(io));
479 io.iov_base = AVAHI_DNS_PACKET_DATA(p);
480 io.iov_len = p->size;
482 memset(&msg, 0, sizeof(msg));
484 msg.msg_namelen = sizeof(sa);
488 msg.msg_control = NULL;
489 msg.msg_controllen = 0;
492 if (interface > 0 || src_address) {
493 struct in_pktinfo *pkti;
495 memset(cmsg_data, 0, sizeof(cmsg_data));
496 cmsg = (struct cmsghdr*) cmsg_data;
497 cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_pktinfo));
498 cmsg->cmsg_level = IPPROTO_IP;
499 cmsg->cmsg_type = IP_PKTINFO;
501 pkti = (struct in_pktinfo*) CMSG_DATA(cmsg);
504 pkti->ipi_ifindex = interface;
507 pkti->ipi_spec_dst.s_addr = src_address->address;
509 msg.msg_control = cmsg_data;
510 msg.msg_controllen = sizeof(cmsg_data);
512 #elif defined(IP_SENDSRCADDR)
514 struct in_addr *addr;
516 memset(cmsg_data, 0, sizeof(cmsg_data));
517 cmsg = (struct cmsghdr*) cmsg_data;
518 cmsg->cmsg_len = CMSG_LEN(sizeof(struct in_addr));
519 cmsg->cmsg_level = IPPROTO_IP;
520 cmsg->cmsg_type = IP_SENDSRCADDR;
522 addr = (struct in_addr *)CMSG_DATA(cmsg);
523 addr->s_addr = src_address->address;
525 msg.msg_control = cmsg_data;
526 msg.msg_controllen = sizeof(cmsg_data);
528 #elif defined(IP_MULTICAST_IF)
530 struct in_addr any = { INADDR_ANY };
531 if (setsockopt(fd, IPPROTO_IP, IP_MULTICAST_IF, src_address ? (const void*) &src_address->address : (const void*) &any, sizeof(struct in_addr)) < 0) {
532 avahi_log_warn("IP_MULTICAST_IF failed: %s", strerror(errno));
536 #elif defined(__GNUC__)
537 #warning "FIXME: We need some code to set the outgoing interface/local address here if IP_PKTINFO/IP_MULTICAST_IF is not available"
540 return sendmsg_loop(fd, &msg, 0);
543 int avahi_send_dns_packet_ipv6(int fd, AvahiIfIndex interface, AvahiDnsPacket *p, const AvahiIPv6Address *src_address, const AvahiIPv6Address *dst_address, uint16_t dst_port) {
544 struct sockaddr_in6 sa;
547 struct cmsghdr *cmsg;
548 size_t cmsg_data[(CMSG_SPACE(sizeof(struct in6_pktinfo))/sizeof(size_t)) + 1];
552 assert(avahi_dns_packet_check_valid(p) >= 0);
553 assert(!dst_address || dst_port > 0);
556 mdns_mcast_group_ipv6(&sa);
558 ipv6_address_to_sockaddr(&sa, dst_address, dst_port);
560 memset(&io, 0, sizeof(io));
561 io.iov_base = AVAHI_DNS_PACKET_DATA(p);
562 io.iov_len = p->size;
564 memset(&msg, 0, sizeof(msg));
566 msg.msg_namelen = sizeof(sa);
571 if (interface > 0 || src_address) {
572 struct in6_pktinfo *pkti;
574 memset(cmsg_data, 0, sizeof(cmsg_data));
575 cmsg = (struct cmsghdr*) cmsg_data;
576 cmsg->cmsg_len = CMSG_LEN(sizeof(struct in6_pktinfo));
577 cmsg->cmsg_level = IPPROTO_IPV6;
578 cmsg->cmsg_type = IPV6_PKTINFO;
580 pkti = (struct in6_pktinfo*) CMSG_DATA(cmsg);
583 pkti->ipi6_ifindex = interface;
586 memcpy(&pkti->ipi6_addr, src_address->address, sizeof(src_address->address));
588 msg.msg_control = cmsg_data;
589 msg.msg_controllen = sizeof(cmsg_data);
591 msg.msg_control = NULL;
592 msg.msg_controllen = 0;
595 return sendmsg_loop(fd, &msg, 0);
598 AvahiDnsPacket *avahi_recv_dns_packet_ipv4(int fd, AvahiIPv4Address *ret_src_address, uint16_t *ret_src_port, AvahiIPv4Address *ret_dst_address, AvahiIfIndex *ret_iface, uint8_t *ret_ttl) {
599 AvahiDnsPacket *p= NULL;
602 size_t aux[1024 / sizeof(size_t)]; /* for alignment on ia64 ! */
604 struct cmsghdr *cmsg;
607 struct sockaddr_in sa;
611 if (ioctl(fd, FIONREAD, &ms) < 0) {
612 avahi_log_warn("ioctl(): %s", strerror(errno));
616 p = avahi_dns_packet_new(ms + AVAHI_DNS_PACKET_EXTRA_SIZE);
618 io.iov_base = AVAHI_DNS_PACKET_DATA(p);
619 io.iov_len = p->max_size;
621 memset(&msg, 0, sizeof(msg));
623 msg.msg_namelen = sizeof(sa);
626 msg.msg_control = aux;
627 msg.msg_controllen = sizeof(aux);
630 if ((l = recvmsg(fd, &msg, 0)) < 0) {
631 avahi_log_warn("recvmsg(): %s", strerror(errno));
635 if (sa.sin_addr.s_addr == INADDR_ANY) {
636 /* Linux 2.4 behaves very strangely sometimes! */
640 assert(!(msg.msg_flags & MSG_CTRUNC));
641 assert(!(msg.msg_flags & MSG_TRUNC));
643 p->size = (size_t) l;
646 *ret_src_port = avahi_port_from_sockaddr((struct sockaddr*) &sa);
648 if (ret_src_address) {
650 avahi_address_from_sockaddr((struct sockaddr*) &sa, &a);
651 *ret_src_address = a.data.ipv4;
658 *ret_iface = AVAHI_IF_UNSPEC;
660 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
662 if (cmsg->cmsg_level == IPPROTO_IP) {
664 switch (cmsg->cmsg_type) {
670 *ret_ttl = (uint8_t) (*(int *) CMSG_DATA(cmsg));
676 struct in_pktinfo *i = (struct in_pktinfo*) CMSG_DATA(cmsg);
679 *ret_iface = (int) i->ipi_ifindex;
682 ret_dst_address->address = i->ipi_addr.s_addr;
692 struct sockaddr_dl *sdl = (struct sockaddr_dl *) CMSG_DATA (cmsg);
695 *ret_iface = (int) sdl->sdl_index;
701 #ifdef IP_RECVDSTADDR
704 memcpy(&ret_dst_address->address, CMSG_DATA (cmsg), 4);
711 avahi_log_warn("Unhandled cmsg_type : %d", cmsg->cmsg_type);
723 avahi_dns_packet_free(p);
728 AvahiDnsPacket *avahi_recv_dns_packet_ipv6(int fd, AvahiIPv6Address *ret_src_address, uint16_t *ret_src_port, AvahiIPv6Address *ret_dst_address, AvahiIfIndex *ret_iface, uint8_t *ret_ttl) {
729 AvahiDnsPacket *p = NULL;
732 size_t aux[1024 / sizeof(size_t)];
735 struct cmsghdr *cmsg;
736 int found_ttl = 0, found_iface = 0;
737 struct sockaddr_in6 sa;
741 if (ioctl(fd, FIONREAD, &ms) < 0) {
742 avahi_log_warn("ioctl(): %s", strerror(errno));
746 p = avahi_dns_packet_new(ms + AVAHI_DNS_PACKET_EXTRA_SIZE);
748 io.iov_base = AVAHI_DNS_PACKET_DATA(p);
749 io.iov_len = p->max_size;
751 memset(&msg, 0, sizeof(msg));
752 msg.msg_name = (struct sockaddr*) &sa;
753 msg.msg_namelen = sizeof(sa);
757 msg.msg_control = aux;
758 msg.msg_controllen = sizeof(aux);
761 if ((l = recvmsg(fd, &msg, 0)) < 0) {
762 avahi_log_warn("recvmsg(): %s", strerror(errno));
766 assert(!(msg.msg_flags & MSG_CTRUNC));
767 assert(!(msg.msg_flags & MSG_TRUNC));
769 p->size = (size_t) l;
772 *ret_src_port = avahi_port_from_sockaddr((struct sockaddr*) &sa);
774 if (ret_src_address) {
776 avahi_address_from_sockaddr((struct sockaddr*) &sa, &a);
777 *ret_src_address = a.data.ipv6;
780 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg != NULL; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
782 if (cmsg->cmsg_level == IPPROTO_IPV6) {
784 switch (cmsg->cmsg_type) {
789 *ret_ttl = (uint8_t) (*(int *) CMSG_DATA(cmsg));
796 struct in6_pktinfo *i = (struct in6_pktinfo*) CMSG_DATA(cmsg);
799 *ret_iface = i->ipi6_ifindex;
802 memcpy(ret_dst_address->address, i->ipi6_addr.s6_addr, 16);
809 avahi_log_warn("Unhandled cmsg_type : %d", cmsg->cmsg_type);
822 avahi_dns_packet_free(p);
827 int avahi_open_unicast_socket_ipv4(void) {
828 struct sockaddr_in local;
831 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
832 avahi_log_warn("socket() failed: %s", strerror(errno));
836 memset(&local, 0, sizeof(local));
837 local.sin_family = AF_INET;
839 if (bind(fd, (struct sockaddr*) &local, sizeof(local)) < 0) {
840 avahi_log_warn("bind() failed: %s", strerror(errno));
844 if (ipv4_pktinfo(fd) < 0) {
848 if (avahi_set_cloexec(fd) < 0) {
849 avahi_log_warn("FD_CLOEXEC failed: %s", strerror(errno));
853 if (avahi_set_nonblock(fd) < 0) {
854 avahi_log_warn("O_NONBLOCK failed: %s", strerror(errno));
867 int avahi_open_unicast_socket_ipv6(void) {
868 struct sockaddr_in6 local;
871 if ((fd = socket(AF_INET6, SOCK_DGRAM, 0)) < 0) {
872 avahi_log_warn("socket() failed: %s", strerror(errno));
876 memset(&local, 0, sizeof(local));
877 local.sin6_family = AF_INET6;
879 if (bind(fd, (struct sockaddr*) &local, sizeof(local)) < 0) {
880 avahi_log_warn("bind() failed: %s", strerror(errno));
884 if (ipv6_pktinfo(fd) < 0)
887 if (avahi_set_cloexec(fd) < 0) {
888 avahi_log_warn("FD_CLOEXEC failed: %s", strerror(errno));
892 if (avahi_set_nonblock(fd) < 0) {
893 avahi_log_warn("O_NONBLOCK failed: %s", strerror(errno));