[systemd.git] / src / resolve / resolved-llmnr.c

/* SPDX-License-Identifier: LGPL-2.1+ */
/***
  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 <netinet/in.h>
#include <resolv.h>

#include "fd-util.h"
#include "resolved-llmnr.h"
#include "resolved-manager.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 == RESOLVE_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("Another LLMNR responder prohibits binding the socket to the same port. Turning off LLMNR support.");
        m->llmnr_support = RESOLVE_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;

        assert(s);
        assert(fd >= 0);
        assert(m);

        r = manager_recv(m, fd, DNS_PROTOCOL_LLMNR, &p);
        if (r <= 0)
                return r;

        if (manager_our_packet(m, p))
                return 0;

        scope = manager_find_scope(m, p);
        if (!scope) {
                log_debug("Got LLMNR UDP packet on unknown scope. Ignoring.");
                return 0;
        }

        if (dns_packet_validate_reply(p) > 0) {
                log_debug("Got LLMNR UDP 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 UDP query packet for id %u", DNS_PACKET_ID(p));

                dns_scope_process_query(scope, NULL, p);
        } else
                log_debug("Invalid LLMNR UDP packet, ignoring.");

        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 log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to create socket: %m");

        /* 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 = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_TTL: %m");
                goto fail;
        }

        r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));
        if (r < 0) {
                r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_TTL: %m");
                goto fail;
        }

        r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_LOOP, &one, sizeof(one));
        if (r < 0) {
                r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_LOOP: %m");
                goto fail;
        }

        r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
        if (r < 0) {
                r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_PKTINFO: %m");
                goto fail;
        }

        r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one));
        if (r < 0) {
                r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_RECVTTL: %m");
                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 = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_MTU_DISCOVER: %m");
                goto fail;
        }

        /* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
        r = bind(m->llmnr_ipv4_udp_fd, &sa.sa, sizeof(sa.in));
        if (r < 0) {
                if (errno != EADDRINUSE) {
                        r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to bind socket: %m");
                        goto fail;
                }

                log_warning("LLMNR-IPv4(UDP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");

                /* try again with SO_REUSEADDR */
                r = setsockopt(m->llmnr_ipv4_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
                if (r < 0) {
                        r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set SO_REUSEADDR: %m");
                        goto fail;
                }

                r = bind(m->llmnr_ipv4_udp_fd, &sa.sa, sizeof(sa.in));
                if (r < 0) {
                        r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to bind socket: %m");
                        goto fail;
                }
        } else {
                /* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
                r = setsockopt(m->llmnr_ipv4_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
                if (r < 0) {
                        r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set SO_REUSEADDR: %m");
                        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;

        (void) sd_event_source_set_description(m->llmnr_ipv4_udp_event_source, "llmnr-ipv4-udp");

        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 log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to create socket: %m");

        r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl));
        if (r < 0) {
                r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_UNICAST_HOPS: %m");
                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 = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_MULTICAST_HOPS: %m");
                goto fail;
        }

        r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &one, sizeof(one));
        if (r < 0) {
                r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_MULTICAST_LOOP: %m");
                goto fail;
        }

        r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
        if (r < 0) {
                r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_V6ONLY: %m");
                goto fail;
        }

        r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
        if (r < 0) {
                r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_RECVPKTINFO: %m");
                goto fail;
        }

        r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
        if (r < 0) {
                r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_RECVHOPLIMIT: %m");
                goto fail;
        }

        /* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
        r = bind(m->llmnr_ipv6_udp_fd, &sa.sa, sizeof(sa.in6));
        if (r < 0) {
                if (errno != EADDRINUSE) {
                        r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to bind socket: %m");
                        goto fail;
                }

                log_warning("LLMNR-IPv6(UDP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");

                /* try again with SO_REUSEADDR */
                r = setsockopt(m->llmnr_ipv6_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
                if (r < 0) {
                        r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set SO_REUSEADDR: %m");
                        goto fail;
                }

                r = bind(m->llmnr_ipv6_udp_fd, &sa.sa, sizeof(sa.in6));
                if (r < 0) {
                        r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to bind socket: %m");
                        goto fail;
                }
        } else {
                /* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
                r = setsockopt(m->llmnr_ipv6_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
                if (r < 0) {
                        r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set SO_REUSEADDR: %m");
                        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)
                goto fail;

        (void) sd_event_source_set_description(m->llmnr_ipv6_udp_event_source, "llmnr-ipv6-udp");

        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);
        assert(s->read_packet);

        scope = manager_find_scope(s->manager, s->read_packet);
        if (!scope)
                log_debug("Got LLMNR TCP packet on unknown scope. Ignoring.");
        else if (dns_packet_validate_query(s->read_packet) > 0) {
                log_debug("Got LLMNR TCP query packet for id %u", DNS_PACKET_ID(s->read_packet));

                dns_scope_process_query(scope, s, s->read_packet);
        } else
                log_debug("Invalid LLMNR TCP packet, ignoring.");

        dns_stream_unref(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 (IN_SET(errno, EAGAIN, 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 log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to create socket: %m");

        /* 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 = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_TTL: %m");
                goto fail;
        }

        r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
        if (r < 0) {
                r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_PKTINFO: %m");
                goto fail;
        }

        r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one));
        if (r < 0) {
                r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_RECVTTL: %m");
                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 = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_MTU_DISCOVER: %m");
                goto fail;
        }

        /* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
        r = bind(m->llmnr_ipv4_tcp_fd, &sa.sa, sizeof(sa.in));
        if (r < 0) {
                if (errno != EADDRINUSE) {
                        r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to bind socket: %m");
                        goto fail;
                }

                log_warning("LLMNR-IPv4(TCP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");

                /* try again with SO_REUSEADDR */
                r = setsockopt(m->llmnr_ipv4_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
                if (r < 0) {
                        r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set SO_REUSEADDR: %m");
                        goto fail;
                }

                r = bind(m->llmnr_ipv4_tcp_fd, &sa.sa, sizeof(sa.in));
                if (r < 0) {
                        r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to bind socket: %m");
                        goto fail;
                }
        } else {
                /* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
                r = setsockopt(m->llmnr_ipv4_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
                if (r < 0) {
                        r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set SO_REUSEADDR: %m");
                        goto fail;
                }
        }

        r = listen(m->llmnr_ipv4_tcp_fd, SOMAXCONN);
        if (r < 0) {
                r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to listen the stream: %m");
                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;

        (void) sd_event_source_set_description(m->llmnr_ipv4_tcp_event_source, "llmnr-ipv4-tcp");

        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 log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to create socket: %m");

        /* 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 = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_UNICAST_HOPS: %m");
                goto fail;
        }

        r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
        if (r < 0) {
                r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_V6ONLY: %m");
                goto fail;
        }

        r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
        if (r < 0) {
                r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_RECVPKTINFO: %m");
                goto fail;
        }

        r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
        if (r < 0) {
                r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_RECVHOPLIMIT: %m");
                goto fail;
        }

        /* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
        r = bind(m->llmnr_ipv6_tcp_fd, &sa.sa, sizeof(sa.in6));
        if (r < 0) {
                if (errno != EADDRINUSE) {
                        r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to bind socket: %m");
                        goto fail;
                }

                log_warning("LLMNR-IPv6(TCP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");

                /* try again with SO_REUSEADDR */
                r = setsockopt(m->llmnr_ipv6_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
                if (r < 0) {
                        r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set SO_REUSEADDR: %m");
                        goto fail;
                }

                r = bind(m->llmnr_ipv6_tcp_fd, &sa.sa, sizeof(sa.in6));
                if (r < 0) {
                        r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to bind socket: %m");
                        goto fail;
                }
        } else {
                /* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
                r = setsockopt(m->llmnr_ipv6_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
                if (r < 0) {
                        r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set SO_REUSEADDR: %m");
                        goto fail;
                }
        }

        r = listen(m->llmnr_ipv6_tcp_fd, SOMAXCONN);
        if (r < 0) {
                r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to listen the stream: %m");
                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)
                goto fail;

        (void) sd_event_source_set_description(m->llmnr_ipv6_tcp_event_source, "llmnr-ipv6-tcp");

        return m->llmnr_ipv6_tcp_fd;

fail:
        m->llmnr_ipv6_tcp_fd = safe_close(m->llmnr_ipv6_tcp_fd);
        return r;
}
Commit	Line	Data
52ad194e	1	/* SPDX-License-Identifier: LGPL-2.1+ */
7035cd9e MP	2	/***
	3	This file is part of systemd.
	4
	5	Copyright 2014 Tom Gundersen <teg@jklm.no>
	6
	7	systemd is free software; you can redistribute it and/or modify it
	8	under the terms of the GNU Lesser General Public License as published by
	9	the Free Software Foundation; either version 2.1 of the License, or
	10	(at your option) any later version.
	11
	12	systemd is distributed in the hope that it will be useful, but
	13	WITHOUT ANY WARRANTY; without even the implied warranty of
	14	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	15	Lesser General Public License for more details.
	16
	17	You should have received a copy of the GNU Lesser General Public License
	18	along with systemd; If not, see <http://www.gnu.org/licenses/>.
	19	***/
	20
7035cd9e	21	#include <netinet/in.h>
db2df898	22	#include <resolv.h>
7035cd9e	23
db2df898	24	#include "fd-util.h"
7035cd9e	25	#include "resolved-llmnr.h"
db2df898	26	#include "resolved-manager.h"
7035cd9e MP	27
	28	void manager_llmnr_stop(Manager *m) {
	29	assert(m);
	30
	31	m->llmnr_ipv4_udp_event_source = sd_event_source_unref(m->llmnr_ipv4_udp_event_source);
	32	m->llmnr_ipv4_udp_fd = safe_close(m->llmnr_ipv4_udp_fd);
	33
	34	m->llmnr_ipv6_udp_event_source = sd_event_source_unref(m->llmnr_ipv6_udp_event_source);
	35	m->llmnr_ipv6_udp_fd = safe_close(m->llmnr_ipv6_udp_fd);
	36
	37	m->llmnr_ipv4_tcp_event_source = sd_event_source_unref(m->llmnr_ipv4_tcp_event_source);
	38	m->llmnr_ipv4_tcp_fd = safe_close(m->llmnr_ipv4_tcp_fd);
	39
	40	m->llmnr_ipv6_tcp_event_source = sd_event_source_unref(m->llmnr_ipv6_tcp_event_source);
	41	m->llmnr_ipv6_tcp_fd = safe_close(m->llmnr_ipv6_tcp_fd);
	42	}
	43
	44	int manager_llmnr_start(Manager *m) {
	45	int r;
	46
	47	assert(m);
	48
4c89c718	49	if (m->llmnr_support == RESOLVE_SUPPORT_NO)
7035cd9e MP	50	return 0;
	51
	52	r = manager_llmnr_ipv4_udp_fd(m);
	53	if (r == -EADDRINUSE)
	54	goto eaddrinuse;
	55	if (r < 0)
	56	return r;
	57
	58	r = manager_llmnr_ipv4_tcp_fd(m);
	59	if (r == -EADDRINUSE)
	60	goto eaddrinuse;
	61	if (r < 0)
	62	return r;
	63
	64	if (socket_ipv6_is_supported()) {
	65	r = manager_llmnr_ipv6_udp_fd(m);
	66	if (r == -EADDRINUSE)
	67	goto eaddrinuse;
	68	if (r < 0)
	69	return r;
	70
	71	r = manager_llmnr_ipv6_tcp_fd(m);
	72	if (r == -EADDRINUSE)
	73	goto eaddrinuse;
	74	if (r < 0)
	75	return r;
	76	}
	77
	78	return 0;
	79
	80	eaddrinuse:
81c58355	81	log_warning("Another LLMNR responder prohibits binding the socket to the same port. Turning off LLMNR support.");
4c89c718	82	m->llmnr_support = RESOLVE_SUPPORT_NO;
7035cd9e MP	83	manager_llmnr_stop(m);
	84
	85	return 0;
	86	}
	87
	88	static int on_llmnr_packet(sd_event_source s, int fd, uint32_t revents, void userdata) {
	89	_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
	90	DnsTransaction *t = NULL;
	91	Manager *m = userdata;
	92	DnsScope *scope;
	93	int r;
	94
5a920b42 MP	95	assert(s);
	96	assert(fd >= 0);
	97	assert(m);
	98
7035cd9e MP	99	r = manager_recv(m, fd, DNS_PROTOCOL_LLMNR, &p);
	100	if (r <= 0)
	101	return r;
	102
52ad194e MB	103	if (manager_our_packet(m, p))
	104	return 0;
	105
7035cd9e	106	scope = manager_find_scope(m, p);
52ad194e MB	107	if (!scope) {
	108	log_debug("Got LLMNR UDP packet on unknown scope. Ignoring.");
	109	return 0;
	110	}
	111
	112	if (dns_packet_validate_reply(p) > 0) {
5a920b42	113	log_debug("Got LLMNR UDP reply packet for id %u", DNS_PACKET_ID(p));
7035cd9e MP	114
	115	dns_scope_check_conflicts(scope, p);
	116
	117	t = hashmap_get(m->dns_transactions, UINT_TO_PTR(DNS_PACKET_ID(p)));
	118	if (t)
	119	dns_transaction_process_reply(t, p);
	120
	121	} else if (dns_packet_validate_query(p) > 0) {
5a920b42	122	log_debug("Got LLMNR UDP query packet for id %u", DNS_PACKET_ID(p));
7035cd9e MP	123
	124	dns_scope_process_query(scope, NULL, p);
	125	} else
4c89c718	126	log_debug("Invalid LLMNR UDP packet, ignoring.");
7035cd9e MP	127
	128	return 0;
	129	}
	130
	131	int manager_llmnr_ipv4_udp_fd(Manager *m) {
	132	union sockaddr_union sa = {
	133	.in.sin_family = AF_INET,
	134	.in.sin_port = htobe16(LLMNR_PORT),
	135	};
	136	static const int one = 1, pmtu = IP_PMTUDISC_DONT, ttl = 255;
	137	int r;
	138
	139	assert(m);
	140
	141	if (m->llmnr_ipv4_udp_fd >= 0)
	142	return m->llmnr_ipv4_udp_fd;
	143
	144	m->llmnr_ipv4_udp_fd = socket(AF_INET, SOCK_DGRAM\|SOCK_CLOEXEC\|SOCK_NONBLOCK, 0);
	145	if (m->llmnr_ipv4_udp_fd < 0)
81c58355	146	return log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to create socket: %m");
7035cd9e MP	147
	148	/* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
	149	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl));
	150	if (r < 0) {
81c58355	151	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_TTL: %m");
7035cd9e MP	152	goto fail;
	153	}
	154
	155	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));
	156	if (r < 0) {
81c58355	157	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_TTL: %m");
7035cd9e MP	158	goto fail;
	159	}
	160
	161	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_LOOP, &one, sizeof(one));
	162	if (r < 0) {
81c58355	163	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_LOOP: %m");
7035cd9e MP	164	goto fail;
	165	}
	166
	167	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
	168	if (r < 0) {
81c58355	169	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_PKTINFO: %m");
7035cd9e MP	170	goto fail;
	171	}
	172
	173	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one));
	174	if (r < 0) {
81c58355	175	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_RECVTTL: %m");
7035cd9e MP	176	goto fail;
	177	}
	178
	179	/* Disable Don't-Fragment bit in the IP header */
	180	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MTU_DISCOVER, &pmtu, sizeof(pmtu));
	181	if (r < 0) {
81c58355	182	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_MTU_DISCOVER: %m");
7035cd9e MP	183	goto fail;
	184	}
	185
81c58355	186	/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
7035cd9e MP	187	r = bind(m->llmnr_ipv4_udp_fd, &sa.sa, sizeof(sa.in));
7035cd9e MP	188	if (r < 0) {
81c58355 MB	189	if (errno != EADDRINUSE) {
	190	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to bind socket: %m");
	191	goto fail;
	192	}
	193
	194	log_warning("LLMNR-IPv4(UDP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
	195
	196	/* try again with SO_REUSEADDR */
	197	r = setsockopt(m->llmnr_ipv4_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	198	if (r < 0) {
	199	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set SO_REUSEADDR: %m");
	200	goto fail;
	201	}
	202
	203	r = bind(m->llmnr_ipv4_udp_fd, &sa.sa, sizeof(sa.in));
	204	if (r < 0) {
	205	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to bind socket: %m");
	206	goto fail;
	207	}
	208	} else {
	209	/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
	210	r = setsockopt(m->llmnr_ipv4_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	211	if (r < 0) {
	212	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set SO_REUSEADDR: %m");
	213	goto fail;
	214	}
7035cd9e MP	215	}
	216
	217	r = sd_event_add_io(m->event, &m->llmnr_ipv4_udp_event_source, m->llmnr_ipv4_udp_fd, EPOLLIN, on_llmnr_packet, m);
	218	if (r < 0)
	219	goto fail;
	220
4c89c718 MP	221	(void) sd_event_source_set_description(m->llmnr_ipv4_udp_event_source, "llmnr-ipv4-udp");
4c89c718 MP	222
7035cd9e MP	223	return m->llmnr_ipv4_udp_fd;
	224
	225	fail:
	226	m->llmnr_ipv4_udp_fd = safe_close(m->llmnr_ipv4_udp_fd);
	227	return r;
	228	}
	229
	230	int manager_llmnr_ipv6_udp_fd(Manager *m) {
	231	union sockaddr_union sa = {
	232	.in6.sin6_family = AF_INET6,
	233	.in6.sin6_port = htobe16(LLMNR_PORT),
	234	};
	235	static const int one = 1, ttl = 255;
	236	int r;
	237
	238	assert(m);
	239
	240	if (m->llmnr_ipv6_udp_fd >= 0)
	241	return m->llmnr_ipv6_udp_fd;
	242
	243	m->llmnr_ipv6_udp_fd = socket(AF_INET6, SOCK_DGRAM\|SOCK_CLOEXEC\|SOCK_NONBLOCK, 0);
	244	if (m->llmnr_ipv6_udp_fd < 0)
81c58355	245	return log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to create socket: %m");
7035cd9e MP	246
	247	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl));
	248	if (r < 0) {
81c58355	249	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_UNICAST_HOPS: %m");
7035cd9e MP	250	goto fail;
	251	}
	252
	253	/* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
	254	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl));
	255	if (r < 0) {
81c58355	256	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_MULTICAST_HOPS: %m");
7035cd9e MP	257	goto fail;
	258	}
	259
	260	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &one, sizeof(one));
	261	if (r < 0) {
81c58355	262	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_MULTICAST_LOOP: %m");
7035cd9e MP	263	goto fail;
	264	}
	265
	266	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
	267	if (r < 0) {
81c58355	268	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_V6ONLY: %m");
7035cd9e MP	269	goto fail;
	270	}
	271
	272	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
	273	if (r < 0) {
81c58355	274	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_RECVPKTINFO: %m");
7035cd9e MP	275	goto fail;
	276	}
	277
	278	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
	279	if (r < 0) {
81c58355	280	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_RECVHOPLIMIT: %m");
7035cd9e MP	281	goto fail;
	282	}
	283
81c58355	284	/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
7035cd9e MP	285	r = bind(m->llmnr_ipv6_udp_fd, &sa.sa, sizeof(sa.in6));
7035cd9e MP	286	if (r < 0) {
81c58355 MB	287	if (errno != EADDRINUSE) {
	288	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to bind socket: %m");
	289	goto fail;
	290	}
	291
	292	log_warning("LLMNR-IPv6(UDP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
	293
	294	/* try again with SO_REUSEADDR */
	295	r = setsockopt(m->llmnr_ipv6_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	296	if (r < 0) {
	297	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set SO_REUSEADDR: %m");
	298	goto fail;
	299	}
	300
	301	r = bind(m->llmnr_ipv6_udp_fd, &sa.sa, sizeof(sa.in6));
	302	if (r < 0) {
	303	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to bind socket: %m");
	304	goto fail;
	305	}
	306	} else {
	307	/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
	308	r = setsockopt(m->llmnr_ipv6_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	309	if (r < 0) {
	310	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set SO_REUSEADDR: %m");
	311	goto fail;
	312	}
7035cd9e MP	313	}
	314
	315	r = sd_event_add_io(m->event, &m->llmnr_ipv6_udp_event_source, m->llmnr_ipv6_udp_fd, EPOLLIN, on_llmnr_packet, m);
4c89c718	316	if (r < 0)
7035cd9e	317	goto fail;
4c89c718 MP	318
4c89c718 MP	319	(void) sd_event_source_set_description(m->llmnr_ipv6_udp_event_source, "llmnr-ipv6-udp");
7035cd9e MP	320
	321	return m->llmnr_ipv6_udp_fd;
	322
	323	fail:
	324	m->llmnr_ipv6_udp_fd = safe_close(m->llmnr_ipv6_udp_fd);
	325	return r;
	326	}
	327
	328	static int on_llmnr_stream_packet(DnsStream *s) {
	329	DnsScope *scope;
	330
	331	assert(s);
5a920b42	332	assert(s->read_packet);
7035cd9e MP	333
7035cd9e MP	334	scope = manager_find_scope(s->manager, s->read_packet);
5a920b42	335	if (!scope)
52ad194e	336	log_debug("Got LLMNR TCP packet on unknown scope. Ignoring.");
5a920b42 MP	337	else if (dns_packet_validate_query(s->read_packet) > 0) {
5a920b42 MP	338	log_debug("Got LLMNR TCP query packet for id %u", DNS_PACKET_ID(s->read_packet));
7035cd9e MP	339
7035cd9e MP	340	dns_scope_process_query(scope, s, s->read_packet);
7035cd9e	341	} else
5a920b42	342	log_debug("Invalid LLMNR TCP packet, ignoring.");
7035cd9e	343
5a920b42	344	dns_stream_unref(s);
7035cd9e MP	345	return 0;
	346	}
	347
	348	static int on_llmnr_stream(sd_event_source s, int fd, uint32_t revents, void userdata) {
	349	DnsStream *stream;
	350	Manager *m = userdata;
	351	int cfd, r;
	352
	353	cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK\|SOCK_CLOEXEC);
	354	if (cfd < 0) {
f5e65279	355	if (IN_SET(errno, EAGAIN, EINTR))
7035cd9e MP	356	return 0;
	357
	358	return -errno;
	359	}
	360
	361	r = dns_stream_new(m, &stream, DNS_PROTOCOL_LLMNR, cfd);
	362	if (r < 0) {
	363	safe_close(cfd);
	364	return r;
	365	}
	366
	367	stream->on_packet = on_llmnr_stream_packet;
	368	return 0;
	369	}
	370
	371	int manager_llmnr_ipv4_tcp_fd(Manager *m) {
	372	union sockaddr_union sa = {
	373	.in.sin_family = AF_INET,
	374	.in.sin_port = htobe16(LLMNR_PORT),
	375	};
	376	static const int one = 1, pmtu = IP_PMTUDISC_DONT;
	377	int r;
	378
	379	assert(m);
	380
	381	if (m->llmnr_ipv4_tcp_fd >= 0)
	382	return m->llmnr_ipv4_tcp_fd;
	383
	384	m->llmnr_ipv4_tcp_fd = socket(AF_INET, SOCK_STREAM\|SOCK_CLOEXEC\|SOCK_NONBLOCK, 0);
	385	if (m->llmnr_ipv4_tcp_fd < 0)
81c58355	386	return log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to create socket: %m");
7035cd9e MP	387
	388	/* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */
	389	r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_TTL, &one, sizeof(one));
	390	if (r < 0) {
81c58355	391	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_TTL: %m");
7035cd9e MP	392	goto fail;
	393	}
	394
	395	r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
	396	if (r < 0) {
81c58355	397	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_PKTINFO: %m");
7035cd9e MP	398	goto fail;
	399	}
	400
	401	r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one));
	402	if (r < 0) {
81c58355	403	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_RECVTTL: %m");
7035cd9e MP	404	goto fail;
	405	}
	406
	407	/* Disable Don't-Fragment bit in the IP header */
	408	r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_MTU_DISCOVER, &pmtu, sizeof(pmtu));
	409	if (r < 0) {
81c58355	410	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_MTU_DISCOVER: %m");
7035cd9e MP	411	goto fail;
	412	}
	413
81c58355	414	/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
7035cd9e MP	415	r = bind(m->llmnr_ipv4_tcp_fd, &sa.sa, sizeof(sa.in));
7035cd9e MP	416	if (r < 0) {
81c58355 MB	417	if (errno != EADDRINUSE) {
	418	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to bind socket: %m");
	419	goto fail;
	420	}
	421
	422	log_warning("LLMNR-IPv4(TCP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
	423
	424	/* try again with SO_REUSEADDR */
	425	r = setsockopt(m->llmnr_ipv4_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	426	if (r < 0) {
	427	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set SO_REUSEADDR: %m");
	428	goto fail;
	429	}
	430
	431	r = bind(m->llmnr_ipv4_tcp_fd, &sa.sa, sizeof(sa.in));
	432	if (r < 0) {
	433	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to bind socket: %m");
	434	goto fail;
	435	}
	436	} else {
	437	/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
	438	r = setsockopt(m->llmnr_ipv4_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	439	if (r < 0) {
	440	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set SO_REUSEADDR: %m");
	441	goto fail;
	442	}
7035cd9e MP	443	}
	444
	445	r = listen(m->llmnr_ipv4_tcp_fd, SOMAXCONN);
	446	if (r < 0) {
81c58355	447	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to listen the stream: %m");
7035cd9e MP	448	goto fail;
	449	}
	450
	451	r = sd_event_add_io(m->event, &m->llmnr_ipv4_tcp_event_source, m->llmnr_ipv4_tcp_fd, EPOLLIN, on_llmnr_stream, m);
	452	if (r < 0)
	453	goto fail;
	454
4c89c718 MP	455	(void) sd_event_source_set_description(m->llmnr_ipv4_tcp_event_source, "llmnr-ipv4-tcp");
4c89c718 MP	456
7035cd9e MP	457	return m->llmnr_ipv4_tcp_fd;
	458
	459	fail:
	460	m->llmnr_ipv4_tcp_fd = safe_close(m->llmnr_ipv4_tcp_fd);
	461	return r;
	462	}
	463
	464	int manager_llmnr_ipv6_tcp_fd(Manager *m) {
	465	union sockaddr_union sa = {
	466	.in6.sin6_family = AF_INET6,
	467	.in6.sin6_port = htobe16(LLMNR_PORT),
	468	};
	469	static const int one = 1;
	470	int r;
	471
	472	assert(m);
	473
	474	if (m->llmnr_ipv6_tcp_fd >= 0)
	475	return m->llmnr_ipv6_tcp_fd;
	476
	477	m->llmnr_ipv6_tcp_fd = socket(AF_INET6, SOCK_STREAM\|SOCK_CLOEXEC\|SOCK_NONBLOCK, 0);
	478	if (m->llmnr_ipv6_tcp_fd < 0)
81c58355	479	return log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to create socket: %m");
7035cd9e MP	480
	481	/* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */
	482	r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &one, sizeof(one));
	483	if (r < 0) {
81c58355	484	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_UNICAST_HOPS: %m");
7035cd9e MP	485	goto fail;
	486	}
	487
	488	r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
	489	if (r < 0) {
81c58355	490	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_V6ONLY: %m");
7035cd9e MP	491	goto fail;
	492	}
	493
	494	r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
	495	if (r < 0) {
81c58355	496	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_RECVPKTINFO: %m");
7035cd9e MP	497	goto fail;
	498	}
	499
	500	r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
	501	if (r < 0) {
81c58355	502	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_RECVHOPLIMIT: %m");
7035cd9e MP	503	goto fail;
	504	}
	505
81c58355	506	/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
7035cd9e MP	507	r = bind(m->llmnr_ipv6_tcp_fd, &sa.sa, sizeof(sa.in6));
7035cd9e MP	508	if (r < 0) {
81c58355 MB	509	if (errno != EADDRINUSE) {
	510	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to bind socket: %m");
	511	goto fail;
	512	}
	513
	514	log_warning("LLMNR-IPv6(TCP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
	515
	516	/* try again with SO_REUSEADDR */
	517	r = setsockopt(m->llmnr_ipv6_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	518	if (r < 0) {
	519	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set SO_REUSEADDR: %m");
	520	goto fail;
	521	}
	522
	523	r = bind(m->llmnr_ipv6_tcp_fd, &sa.sa, sizeof(sa.in6));
	524	if (r < 0) {
	525	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to bind socket: %m");
	526	goto fail;
	527	}
	528	} else {
	529	/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
	530	r = setsockopt(m->llmnr_ipv6_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	531	if (r < 0) {
	532	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set SO_REUSEADDR: %m");
	533	goto fail;
	534	}
7035cd9e MP	535	}
	536
	537	r = listen(m->llmnr_ipv6_tcp_fd, SOMAXCONN);
	538	if (r < 0) {
81c58355	539	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to listen the stream: %m");
7035cd9e MP	540	goto fail;
	541	}
	542
	543	r = sd_event_add_io(m->event, &m->llmnr_ipv6_tcp_event_source, m->llmnr_ipv6_tcp_fd, EPOLLIN, on_llmnr_stream, m);
4c89c718	544	if (r < 0)
7035cd9e	545	goto fail;
4c89c718 MP	546
4c89c718 MP	547	(void) sd_event_source_set_description(m->llmnr_ipv6_tcp_event_source, "llmnr-ipv6-tcp");
7035cd9e MP	548
	549	return m->llmnr_ipv6_tcp_fd;
	550
	551	fail:
	552	m->llmnr_ipv6_tcp_fd = safe_close(m->llmnr_ipv6_tcp_fd);
	553	return r;
	554	}