/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ /*** This file is part of systemd. Copyright 2014 Tom Gundersen <teg@jklm.no> systemd is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. systemd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with systemd; If not, see <http://www.gnu.org/licenses/>. ***/ #include <resolv.h> #include <netinet/in.h> #include "resolved-manager.h" #include "resolved-llmnr.h" void manager_llmnr_stop(Manager *m) { assert(m); m->llmnr_ipv4_udp_event_source = sd_event_source_unref(m->llmnr_ipv4_udp_event_source); m->llmnr_ipv4_udp_fd = safe_close(m->llmnr_ipv4_udp_fd); m->llmnr_ipv6_udp_event_source = sd_event_source_unref(m->llmnr_ipv6_udp_event_source); m->llmnr_ipv6_udp_fd = safe_close(m->llmnr_ipv6_udp_fd); m->llmnr_ipv4_tcp_event_source = sd_event_source_unref(m->llmnr_ipv4_tcp_event_source); m->llmnr_ipv4_tcp_fd = safe_close(m->llmnr_ipv4_tcp_fd); m->llmnr_ipv6_tcp_event_source = sd_event_source_unref(m->llmnr_ipv6_tcp_event_source); m->llmnr_ipv6_tcp_fd = safe_close(m->llmnr_ipv6_tcp_fd); } int manager_llmnr_start(Manager *m) { int r; assert(m); if (m->llmnr_support == SUPPORT_NO) return 0; r = manager_llmnr_ipv4_udp_fd(m); if (r == -EADDRINUSE) goto eaddrinuse; if (r < 0) return r; r = manager_llmnr_ipv4_tcp_fd(m); if (r == -EADDRINUSE) goto eaddrinuse; if (r < 0) return r; if (socket_ipv6_is_supported()) { r = manager_llmnr_ipv6_udp_fd(m); if (r == -EADDRINUSE) goto eaddrinuse; if (r < 0) return r; r = manager_llmnr_ipv6_tcp_fd(m); if (r == -EADDRINUSE) goto eaddrinuse; if (r < 0) return r; } return 0; eaddrinuse: log_warning("There appears to be another LLMNR responder running. Turning off LLMNR support."); m->llmnr_support = SUPPORT_NO; manager_llmnr_stop(m); return 0; } static int on_llmnr_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) { _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; DnsTransaction *t = NULL; Manager *m = userdata; DnsScope *scope; int r; r = manager_recv(m, fd, DNS_PROTOCOL_LLMNR, &p); if (r <= 0) return r; scope = manager_find_scope(m, p); if (!scope) { log_warning("Got LLMNR UDP packet on unknown scope. Ignoring."); return 0; } if (dns_packet_validate_reply(p) > 0) { log_debug("Got LLMNR reply packet for id %u", DNS_PACKET_ID(p)); dns_scope_check_conflicts(scope, p); t = hashmap_get(m->dns_transactions, UINT_TO_PTR(DNS_PACKET_ID(p))); if (t) dns_transaction_process_reply(t, p); } else if (dns_packet_validate_query(p) > 0) { log_debug("Got LLMNR query packet for id %u", DNS_PACKET_ID(p)); dns_scope_process_query(scope, NULL, p); } else log_debug("Invalid LLMNR UDP packet."); return 0; } int manager_llmnr_ipv4_udp_fd(Manager *m) { union sockaddr_union sa = { .in.sin_family = AF_INET, .in.sin_port = htobe16(LLMNR_PORT), }; static const int one = 1, pmtu = IP_PMTUDISC_DONT, ttl = 255; 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; /* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */ r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl)); if (r < 0) { r = -errno; goto fail; } r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)); 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(LLMNR_PORT), }; static const int one = 1, ttl = 255; 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, &ttl, sizeof(ttl)); if (r < 0) { r = -errno; goto fail; } /* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */ r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl)); 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; } static int on_llmnr_stream_packet(DnsStream *s) { DnsScope *scope; assert(s); scope = manager_find_scope(s->manager, s->read_packet); if (!scope) { log_warning("Got LLMNR TCP packet on unknown scope. Ignroing."); return 0; } if (dns_packet_validate_query(s->read_packet) > 0) { log_debug("Got query packet for id %u", DNS_PACKET_ID(s->read_packet)); dns_scope_process_query(scope, s, s->read_packet); /* If no reply packet was set, we free the stream */ if (s->write_packet) return 0; } else log_debug("Invalid LLMNR TCP packet."); dns_stream_free(s); return 0; } static int on_llmnr_stream(sd_event_source *s, int fd, uint32_t revents, void *userdata) { DnsStream *stream; Manager *m = userdata; int cfd, r; cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC); if (cfd < 0) { if (errno == EAGAIN || errno == EINTR) return 0; return -errno; } r = dns_stream_new(m, &stream, DNS_PROTOCOL_LLMNR, cfd); if (r < 0) { safe_close(cfd); return r; } stream->on_packet = on_llmnr_stream_packet; return 0; } int manager_llmnr_ipv4_tcp_fd(Manager *m) { union sockaddr_union sa = { .in.sin_family = AF_INET, .in.sin_port = htobe16(LLMNR_PORT), }; static const int one = 1, pmtu = IP_PMTUDISC_DONT; int r; assert(m); if (m->llmnr_ipv4_tcp_fd >= 0) return m->llmnr_ipv4_tcp_fd; m->llmnr_ipv4_tcp_fd = socket(AF_INET, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); if (m->llmnr_ipv4_tcp_fd < 0) return -errno; /* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */ r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_TTL, &one, sizeof(one)); if (r < 0) { r = -errno; goto fail; } r = setsockopt(m->llmnr_ipv4_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)); if (r < 0) { r = -errno; goto fail; } r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one)); if (r < 0) { r = -errno; goto fail; } r = setsockopt(m->llmnr_ipv4_tcp_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_tcp_fd, IPPROTO_IP, IP_MTU_DISCOVER, &pmtu, sizeof(pmtu)); if (r < 0) { r = -errno; goto fail; } r = bind(m->llmnr_ipv4_tcp_fd, &sa.sa, sizeof(sa.in)); if (r < 0) { r = -errno; goto fail; } r = listen(m->llmnr_ipv4_tcp_fd, SOMAXCONN); if (r < 0) { r = -errno; goto fail; } r = sd_event_add_io(m->event, &m->llmnr_ipv4_tcp_event_source, m->llmnr_ipv4_tcp_fd, EPOLLIN, on_llmnr_stream, m); if (r < 0) goto fail; return m->llmnr_ipv4_tcp_fd; fail: m->llmnr_ipv4_tcp_fd = safe_close(m->llmnr_ipv4_tcp_fd); return r; } int manager_llmnr_ipv6_tcp_fd(Manager *m) { union sockaddr_union sa = { .in6.sin6_family = AF_INET6, .in6.sin6_port = htobe16(LLMNR_PORT), }; static const int one = 1; int r; assert(m); if (m->llmnr_ipv6_tcp_fd >= 0) return m->llmnr_ipv6_tcp_fd; m->llmnr_ipv6_tcp_fd = socket(AF_INET6, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); if (m->llmnr_ipv6_tcp_fd < 0) return -errno; /* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */ r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &one, sizeof(one)); if (r < 0) { r = -errno; goto fail; } r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one)); if (r < 0) { r = -errno; goto fail; } r = setsockopt(m->llmnr_ipv6_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)); if (r < 0) { r = -errno; goto fail; } r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one)); if (r < 0) { r = -errno; goto fail; } r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one)); if (r < 0) { r = -errno; goto fail; } r = bind(m->llmnr_ipv6_tcp_fd, &sa.sa, sizeof(sa.in6)); if (r < 0) { r = -errno; goto fail; } r = listen(m->llmnr_ipv6_tcp_fd, SOMAXCONN); if (r < 0) { r = -errno; goto fail; } r = sd_event_add_io(m->event, &m->llmnr_ipv6_tcp_event_source, m->llmnr_ipv6_tcp_fd, EPOLLIN, on_llmnr_stream, m); if (r < 0) { r = -errno; goto fail; } return m->llmnr_ipv6_tcp_fd; fail: m->llmnr_ipv6_tcp_fd = safe_close(m->llmnr_ipv6_tcp_fd); return r; }