/* * Copyright (c) 2022 Florian Zschocke * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * Neither the name of the copyright holders nor the names of its * contributors may be used to endorse or promote products derived from * this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ #include "config.h" #include /* needed for u_int on DragonFly BSD */ #include #include #include #include #include #include #include #include #include "libmdnsd/mdnsd.h" #include "mcsock.h" static struct in_addr get_addr(const char *ifname) { struct ifaddrs *ifaddr, *ifa; struct in_addr addr; addr.s_addr = htonl(INADDR_ANY); if (getifaddrs(&ifaddr) < 0) { WARN("Failed getting interfaces: %s", strerror(errno)); return addr; } for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) { if (ifa->ifa_addr != NULL && ifa->ifa_addr->sa_family == AF_INET && strcmp(ifname, ifa->ifa_name) == 0) { addr = ((struct sockaddr_in*)ifa->ifa_addr)->sin_addr; break; } } freeifaddrs(ifaddr); return addr; } static int mc_socket(struct ifnfo *iface, unsigned char ttl) { #ifdef HAVE_STRUCT_IP_MREQN_IMR_IFINDEX struct ip_mreqn imr ={ 0 }; #else struct ip_mreq imr = { 0 }; imr.imr_interface.s_addr = htonl(INADDR_ANY); #endif const unsigned char ena = 1; const int on = 1; #ifdef IP_MULTICAST_ALL const int off = 0; #endif struct sockaddr_in sin; socklen_t len; int unicast_ttl = 255; int bufsiz; int sd; sd = socket(AF_INET, SOCK_DGRAM | SOCK_NONBLOCK, 0); if (sd < 0) { ERR("Failed creating UDP socket: %s", strerror(errno)); return -1; } #ifdef SO_REUSEPORT if (setsockopt(sd, SOL_SOCKET, SO_REUSEPORT, &on, sizeof(on))) WARN("Failed setting SO_REUSEPORT: %s", strerror(errno)); #endif if (setsockopt(sd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on))) WARN("Failed setting SO_REUSEADDR: %s", strerror(errno)); /* Double the size of the receive buffer (getsockopt() returns the double) */ len = sizeof(bufsiz); if (!getsockopt(sd, SOL_SOCKET, SO_RCVBUF, &bufsiz, &len)) { if (setsockopt(sd, SOL_SOCKET, SO_RCVBUF, &bufsiz, sizeof(bufsiz))) INFO("Failed doubling the size of the receive buffer: %s", strerror(errno)); } if (setsockopt(sd, IPPROTO_IP, IP_MULTICAST_LOOP, &ena, sizeof(ena))) WARN("Failed enabling IP_MULTICAST_LOOP on %s: %s", iface->ifname, strerror(errno)); #ifdef IP_MULTICAST_ALL if (setsockopt(sd, IPPROTO_IP, IP_MULTICAST_ALL, &off, sizeof(off))) WARN("Failed disabling IP_MULTICAST_ALL on %s: %s", iface->ifname, strerror(errno)); #endif /* * All traffic on mDNS is link-local only, so the default * TTL is set to 1. Some users may however want to route mDNS. */ if (setsockopt(sd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl))) WARN("Failed setting IP_MULTICAST_TTL to %d: %s", ttl, strerror(errno)); /* mDNS also supports unicast, so we need a relevant TTL there too */ if (setsockopt(sd, IPPROTO_IP, IP_TTL, &unicast_ttl, sizeof(unicast_ttl))) WARN("Failed setting IP_TTL to %d: %s", unicast_ttl, strerror(errno)); if (iface) { if (iface->ifindex != 0 && iface->inaddr.s_addr == 0) { iface->inaddr = get_addr(iface->ifname); } /* Set interface for outbound multicast */ #ifdef HAVE_STRUCT_IP_MREQN_IMR_IFINDEX imr.imr_ifindex = iface->ifindex; if (setsockopt(sd, IPPROTO_IP, IP_MULTICAST_IF, &imr, sizeof(imr))) WARN("Failed setting IP_MULTICAST_IF to %d: %s", iface->ifindex, strerror(errno)); #else imr.imr_interface = iface->inaddr; if (setsockopt(sd, IPPROTO_IP, IP_MULTICAST_IF, &(iface->inaddr), sizeof(struct in_addr))) WARN("Failed setting IP_MULTICAST_IF to %s: %s", inet_ntoa(iface->inaddr), strerror(errno)); #endif #ifdef HAVE_SO_BINDTODEVICE /* Filter inbound traffic from anyone (ANY) to port 5353 on ifname */ if (setsockopt(sd, SOL_SOCKET, SO_BINDTODEVICE, &iface->ifname, strlen(iface->ifname))) INFO("Failed setting SO_BINDTODEVICE on %s: %s", iface->ifname, strerror(errno)); #endif } /* * Join mDNS link-local group on the given interface, that way * we can receive multicast without a proper net route (default * route or a 224.0.0.0/24 net route). */ imr.imr_multiaddr.s_addr = inet_addr("224.0.0.251"); if (setsockopt(sd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &imr, sizeof(imr))) WARN("Failed joining mDNS group 224.0.0.251: %s", strerror(errno)); memset(&sin, 0, sizeof(sin)); sin.sin_family = AF_INET; sin.sin_port = htons(5353); if (bind(sd, (struct sockaddr *)&sin, sizeof(sin))) { close(sd); ERR("Failed binding socket to *:5353: %s", strerror(errno)); return -1; } INFO("Bound to *:5353 on iface %s", iface->ifname); return sd; } int mdns_socket(struct ifnfo *iface, unsigned char ttl) { /* Default to TTL of 1 for mDNS as it is link-local */ if (ttl == 0) ttl = 1; return mc_socket(iface, ttl); } #ifdef ENABLE_IPV6 static int mc_socket6(struct ifnfo *iface, unsigned char ttl) { struct ipv6_mreq mreq = { 0 }; const int hops = ttl; const int unicast_hops = 255; const int on = 1; struct sockaddr_in6 sin6; int sd; sd = socket(AF_INET6, SOCK_DGRAM | SOCK_NONBLOCK, 0); if (sd < 0) { ERR("Failed creating UDP6 socket: %s", strerror(errno)); return -1; } #ifdef SO_REUSEPORT if (setsockopt(sd, SOL_SOCKET, SO_REUSEPORT, &on, sizeof(on))) WARN("Failed setting SO_REUSEPORT: %s", strerror(errno)); #endif if (setsockopt(sd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on))) WARN("Failed setting SO_REUSEADDR: %s", strerror(errno)); /* Keep the v6 socket v6-only so it doesn't shadow the v4 socket */ if (setsockopt(sd, IPPROTO_IPV6, IPV6_V6ONLY, &on, sizeof(on))) WARN("Failed setting IPV6_V6ONLY: %s", strerror(errno)); if (setsockopt(sd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &on, sizeof(on))) WARN("Failed enabling IPV6_MULTICAST_LOOP on %s: %s", iface->ifname, strerror(errno)); /* mDNS is link-local, so hop limit 1; some users may route it */ if (setsockopt(sd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &hops, sizeof(hops))) WARN("Failed setting IPV6_MULTICAST_HOPS to %d: %s", hops, strerror(errno)); if (setsockopt(sd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &unicast_hops, sizeof(unicast_hops))) WARN("Failed setting IPV6_UNICAST_HOPS to %d: %s", unicast_hops, strerror(errno)); if (iface->ifindex) { unsigned int idx = (unsigned int)iface->ifindex; /* Pick the outgoing interface for multicast */ if (setsockopt(sd, IPPROTO_IPV6, IPV6_MULTICAST_IF, &idx, sizeof(idx))) WARN("Failed setting IPV6_MULTICAST_IF to %d: %s", iface->ifindex, strerror(errno)); #ifdef HAVE_SO_BINDTODEVICE if (setsockopt(sd, SOL_SOCKET, SO_BINDTODEVICE, iface->ifname, strlen(iface->ifname))) INFO("Failed setting SO_BINDTODEVICE on %s: %s", iface->ifname, strerror(errno)); #endif } /* Join the mDNS link-local group on the given interface */ inet_pton(AF_INET6, "ff02::fb", &mreq.ipv6mr_multiaddr); mreq.ipv6mr_interface = (unsigned int)iface->ifindex; if (setsockopt(sd, IPPROTO_IPV6, IPV6_JOIN_GROUP, &mreq, sizeof(mreq))) WARN("Failed joining mDNS group ff02::fb: %s", strerror(errno)); memset(&sin6, 0, sizeof(sin6)); sin6.sin6_family = AF_INET6; sin6.sin6_port = htons(5353); sin6.sin6_addr = in6addr_any; if (bind(sd, (struct sockaddr *)&sin6, sizeof(sin6))) { close(sd); ERR("Failed binding socket to [::]:5353: %s", strerror(errno)); return -1; } INFO("Bound to [::]:5353 on iface %s", iface->ifname); return sd; } int mdns_socket6(struct ifnfo *iface, unsigned char ttl) { if (ttl == 0) ttl = 1; return mc_socket6(iface, ttl); } #endif /* ENABLE_IPV6 */