[thirdparty/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;

        scope = manager_find_scope(m, p);
        if (!scope)
                log_warning("Got LLMNR UDP packet on unknown scope. Ignoring.");
        else 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_warning("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
53e1b683	1	/* SPDX-License-Identifier: LGPL-2.1+ */
5f402ae8 DM	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
5f402ae8	21	#include <netinet/in.h>
cf0fbc49	22	#include <resolv.h>
5f402ae8	23
3ffd4af2	24	#include "fd-util.h"
5f402ae8	25	#include "resolved-llmnr.h"
3ffd4af2	26	#include "resolved-manager.h"
5f402ae8 DM	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
af49ca27	49	if (m->llmnr_support == RESOLVE_SUPPORT_NO)
5f402ae8 DM	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:
007ef0a2	81	log_warning("Another LLMNR responder prohibits binding the socket to the same port. Turning off LLMNR support.");
af49ca27	82	m->llmnr_support = RESOLVE_SUPPORT_NO;
5f402ae8 DM	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
b30bf55d LP	95	assert(s);
	96	assert(fd >= 0);
	97	assert(m);
	98
5f402ae8 DM	99	r = manager_recv(m, fd, DNS_PROTOCOL_LLMNR, &p);
	100	if (r <= 0)
	101	return r;
	102
	103	scope = manager_find_scope(m, p);
b30bf55d	104	if (!scope)
5f402ae8	105	log_warning("Got LLMNR UDP packet on unknown scope. Ignoring.");
b30bf55d LP	106	else if (dns_packet_validate_reply(p) > 0) {
b30bf55d LP	107	log_debug("Got LLMNR UDP reply packet for id %u", DNS_PACKET_ID(p));
5f402ae8 DM	108
	109	dns_scope_check_conflicts(scope, p);
	110
	111	t = hashmap_get(m->dns_transactions, UINT_TO_PTR(DNS_PACKET_ID(p)));
	112	if (t)
	113	dns_transaction_process_reply(t, p);
	114
	115	} else if (dns_packet_validate_query(p) > 0) {
b30bf55d	116	log_debug("Got LLMNR UDP query packet for id %u", DNS_PACKET_ID(p));
5f402ae8 DM	117
	118	dns_scope_process_query(scope, NULL, p);
	119	} else
2c6bf498	120	log_debug("Invalid LLMNR UDP packet, ignoring.");
5f402ae8 DM	121
	122	return 0;
	123	}
	124
	125	int manager_llmnr_ipv4_udp_fd(Manager *m) {
	126	union sockaddr_union sa = {
	127	.in.sin_family = AF_INET,
22a37591	128	.in.sin_port = htobe16(LLMNR_PORT),
5f402ae8 DM	129	};
	130	static const int one = 1, pmtu = IP_PMTUDISC_DONT, ttl = 255;
	131	int r;
	132
	133	assert(m);
	134
	135	if (m->llmnr_ipv4_udp_fd >= 0)
	136	return m->llmnr_ipv4_udp_fd;
	137
	138	m->llmnr_ipv4_udp_fd = socket(AF_INET, SOCK_DGRAM\|SOCK_CLOEXEC\|SOCK_NONBLOCK, 0);
	139	if (m->llmnr_ipv4_udp_fd < 0)
007ef0a2	140	return log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to create socket: %m");
5f402ae8 DM	141
	142	/* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
	143	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl));
	144	if (r < 0) {
007ef0a2	145	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_TTL: %m");
5f402ae8 DM	146	goto fail;
	147	}
	148
	149	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));
	150	if (r < 0) {
007ef0a2	151	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_TTL: %m");
5f402ae8 DM	152	goto fail;
	153	}
	154
	155	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_LOOP, &one, sizeof(one));
	156	if (r < 0) {
007ef0a2	157	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_LOOP: %m");
5f402ae8 DM	158	goto fail;
	159	}
	160
	161	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
	162	if (r < 0) {
007ef0a2	163	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_PKTINFO: %m");
5f402ae8 DM	164	goto fail;
	165	}
	166
	167	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one));
	168	if (r < 0) {
007ef0a2	169	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_RECVTTL: %m");
5f402ae8 DM	170	goto fail;
	171	}
	172
	173	/* Disable Don't-Fragment bit in the IP header */
	174	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MTU_DISCOVER, &pmtu, sizeof(pmtu));
	175	if (r < 0) {
007ef0a2	176	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_MTU_DISCOVER: %m");
5f402ae8 DM	177	goto fail;
	178	}
	179
007ef0a2	180	/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
5f402ae8 DM	181	r = bind(m->llmnr_ipv4_udp_fd, &sa.sa, sizeof(sa.in));
5f402ae8 DM	182	if (r < 0) {
007ef0a2 YW	183	if (errno != EADDRINUSE) {
	184	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to bind socket: %m");
	185	goto fail;
	186	}
	187
	188	log_warning("LLMNR-IPv4(UDP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
	189
	190	/* try again with SO_REUSEADDR */
	191	r = setsockopt(m->llmnr_ipv4_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	192	if (r < 0) {
	193	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set SO_REUSEADDR: %m");
	194	goto fail;
	195	}
	196
	197	r = bind(m->llmnr_ipv4_udp_fd, &sa.sa, sizeof(sa.in));
	198	if (r < 0) {
	199	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to bind socket: %m");
	200	goto fail;
	201	}
	202	} else {
	203	/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
	204	r = setsockopt(m->llmnr_ipv4_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	205	if (r < 0) {
	206	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set SO_REUSEADDR: %m");
	207	goto fail;
	208	}
5f402ae8 DM	209	}
	210
	211	r = sd_event_add_io(m->event, &m->llmnr_ipv4_udp_event_source, m->llmnr_ipv4_udp_fd, EPOLLIN, on_llmnr_packet, m);
	212	if (r < 0)
	213	goto fail;
	214
aa4a9deb LP	215	(void) sd_event_source_set_description(m->llmnr_ipv4_udp_event_source, "llmnr-ipv4-udp");
aa4a9deb LP	216
5f402ae8 DM	217	return m->llmnr_ipv4_udp_fd;
	218
	219	fail:
	220	m->llmnr_ipv4_udp_fd = safe_close(m->llmnr_ipv4_udp_fd);
	221	return r;
	222	}
	223
	224	int manager_llmnr_ipv6_udp_fd(Manager *m) {
	225	union sockaddr_union sa = {
	226	.in6.sin6_family = AF_INET6,
22a37591	227	.in6.sin6_port = htobe16(LLMNR_PORT),
5f402ae8 DM	228	};
	229	static const int one = 1, ttl = 255;
	230	int r;
	231
	232	assert(m);
	233
	234	if (m->llmnr_ipv6_udp_fd >= 0)
	235	return m->llmnr_ipv6_udp_fd;
	236
	237	m->llmnr_ipv6_udp_fd = socket(AF_INET6, SOCK_DGRAM\|SOCK_CLOEXEC\|SOCK_NONBLOCK, 0);
	238	if (m->llmnr_ipv6_udp_fd < 0)
007ef0a2	239	return log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to create socket: %m");
5f402ae8 DM	240
	241	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl));
	242	if (r < 0) {
007ef0a2	243	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_UNICAST_HOPS: %m");
5f402ae8 DM	244	goto fail;
	245	}
	246
	247	/* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
	248	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl));
	249	if (r < 0) {
007ef0a2	250	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_MULTICAST_HOPS: %m");
5f402ae8 DM	251	goto fail;
	252	}
	253
	254	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &one, sizeof(one));
	255	if (r < 0) {
007ef0a2	256	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_MULTICAST_LOOP: %m");
5f402ae8 DM	257	goto fail;
	258	}
	259
	260	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
	261	if (r < 0) {
007ef0a2	262	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_V6ONLY: %m");
5f402ae8 DM	263	goto fail;
	264	}
	265
	266	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
	267	if (r < 0) {
007ef0a2	268	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_RECVPKTINFO: %m");
5f402ae8 DM	269	goto fail;
	270	}
	271
	272	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
	273	if (r < 0) {
007ef0a2	274	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_RECVHOPLIMIT: %m");
5f402ae8 DM	275	goto fail;
	276	}
	277
007ef0a2	278	/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
5f402ae8 DM	279	r = bind(m->llmnr_ipv6_udp_fd, &sa.sa, sizeof(sa.in6));
5f402ae8 DM	280	if (r < 0) {
007ef0a2 YW	281	if (errno != EADDRINUSE) {
	282	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to bind socket: %m");
	283	goto fail;
	284	}
	285
	286	log_warning("LLMNR-IPv6(UDP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
	287
	288	/* try again with SO_REUSEADDR */
	289	r = setsockopt(m->llmnr_ipv6_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	290	if (r < 0) {
	291	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set SO_REUSEADDR: %m");
	292	goto fail;
	293	}
	294
	295	r = bind(m->llmnr_ipv6_udp_fd, &sa.sa, sizeof(sa.in6));
	296	if (r < 0) {
	297	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to bind socket: %m");
	298	goto fail;
	299	}
	300	} else {
	301	/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
	302	r = setsockopt(m->llmnr_ipv6_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	303	if (r < 0) {
	304	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set SO_REUSEADDR: %m");
	305	goto fail;
	306	}
5f402ae8 DM	307	}
	308
	309	r = sd_event_add_io(m->event, &m->llmnr_ipv6_udp_event_source, m->llmnr_ipv6_udp_fd, EPOLLIN, on_llmnr_packet, m);
35908b98	310	if (r < 0)
5f402ae8	311	goto fail;
5f402ae8	312
aa4a9deb LP	313	(void) sd_event_source_set_description(m->llmnr_ipv6_udp_event_source, "llmnr-ipv6-udp");
aa4a9deb LP	314
5f402ae8 DM	315	return m->llmnr_ipv6_udp_fd;
	316
	317	fail:
	318	m->llmnr_ipv6_udp_fd = safe_close(m->llmnr_ipv6_udp_fd);
	319	return r;
	320	}
	321
	322	static int on_llmnr_stream_packet(DnsStream *s) {
	323	DnsScope *scope;
	324
	325	assert(s);
b30bf55d	326	assert(s->read_packet);
5f402ae8 DM	327
5f402ae8 DM	328	scope = manager_find_scope(s->manager, s->read_packet);
b30bf55d	329	if (!scope)
0ea929d5	330	log_warning("Got LLMNR TCP packet on unknown scope. Ignoring.");
b30bf55d LP	331	else if (dns_packet_validate_query(s->read_packet) > 0) {
b30bf55d LP	332	log_debug("Got LLMNR TCP query packet for id %u", DNS_PACKET_ID(s->read_packet));
5f402ae8 DM	333
5f402ae8 DM	334	dns_scope_process_query(scope, s, s->read_packet);
5f402ae8	335	} else
b30bf55d	336	log_debug("Invalid LLMNR TCP packet, ignoring.");
5f402ae8	337
b30bf55d	338	dns_stream_unref(s);
5f402ae8 DM	339	return 0;
	340	}
	341
	342	static int on_llmnr_stream(sd_event_source s, int fd, uint32_t revents, void userdata) {
	343	DnsStream *stream;
	344	Manager *m = userdata;
	345	int cfd, r;
	346
	347	cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK\|SOCK_CLOEXEC);
	348	if (cfd < 0) {
3742095b	349	if (IN_SET(errno, EAGAIN, EINTR))
5f402ae8 DM	350	return 0;
	351
	352	return -errno;
	353	}
	354
	355	r = dns_stream_new(m, &stream, DNS_PROTOCOL_LLMNR, cfd);
	356	if (r < 0) {
	357	safe_close(cfd);
	358	return r;
	359	}
	360
	361	stream->on_packet = on_llmnr_stream_packet;
	362	return 0;
	363	}
	364
	365	int manager_llmnr_ipv4_tcp_fd(Manager *m) {
	366	union sockaddr_union sa = {
	367	.in.sin_family = AF_INET,
22a37591	368	.in.sin_port = htobe16(LLMNR_PORT),
5f402ae8 DM	369	};
	370	static const int one = 1, pmtu = IP_PMTUDISC_DONT;
	371	int r;
	372
	373	assert(m);
	374
	375	if (m->llmnr_ipv4_tcp_fd >= 0)
	376	return m->llmnr_ipv4_tcp_fd;
	377
	378	m->llmnr_ipv4_tcp_fd = socket(AF_INET, SOCK_STREAM\|SOCK_CLOEXEC\|SOCK_NONBLOCK, 0);
	379	if (m->llmnr_ipv4_tcp_fd < 0)
007ef0a2	380	return log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to create socket: %m");
5f402ae8 DM	381
	382	/* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */
	383	r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_TTL, &one, sizeof(one));
	384	if (r < 0) {
007ef0a2	385	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_TTL: %m");
5f402ae8 DM	386	goto fail;
	387	}
	388
	389	r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
	390	if (r < 0) {
007ef0a2	391	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_PKTINFO: %m");
5f402ae8 DM	392	goto fail;
	393	}
	394
	395	r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one));
	396	if (r < 0) {
007ef0a2	397	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_RECVTTL: %m");
5f402ae8 DM	398	goto fail;
	399	}
	400
	401	/* Disable Don't-Fragment bit in the IP header */
	402	r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_MTU_DISCOVER, &pmtu, sizeof(pmtu));
	403	if (r < 0) {
007ef0a2	404	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_MTU_DISCOVER: %m");
5f402ae8 DM	405	goto fail;
	406	}
	407
007ef0a2	408	/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
5f402ae8 DM	409	r = bind(m->llmnr_ipv4_tcp_fd, &sa.sa, sizeof(sa.in));
5f402ae8 DM	410	if (r < 0) {
007ef0a2 YW	411	if (errno != EADDRINUSE) {
	412	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to bind socket: %m");
	413	goto fail;
	414	}
	415
	416	log_warning("LLMNR-IPv4(TCP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
	417
	418	/* try again with SO_REUSEADDR */
	419	r = setsockopt(m->llmnr_ipv4_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	420	if (r < 0) {
	421	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set SO_REUSEADDR: %m");
	422	goto fail;
	423	}
	424
	425	r = bind(m->llmnr_ipv4_tcp_fd, &sa.sa, sizeof(sa.in));
	426	if (r < 0) {
	427	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to bind socket: %m");
	428	goto fail;
	429	}
	430	} else {
	431	/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
	432	r = setsockopt(m->llmnr_ipv4_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	433	if (r < 0) {
	434	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set SO_REUSEADDR: %m");
	435	goto fail;
	436	}
5f402ae8 DM	437	}
	438
	439	r = listen(m->llmnr_ipv4_tcp_fd, SOMAXCONN);
	440	if (r < 0) {
007ef0a2	441	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to listen the stream: %m");
5f402ae8 DM	442	goto fail;
	443	}
	444
	445	r = sd_event_add_io(m->event, &m->llmnr_ipv4_tcp_event_source, m->llmnr_ipv4_tcp_fd, EPOLLIN, on_llmnr_stream, m);
	446	if (r < 0)
	447	goto fail;
	448
aa4a9deb LP	449	(void) sd_event_source_set_description(m->llmnr_ipv4_tcp_event_source, "llmnr-ipv4-tcp");
aa4a9deb LP	450
5f402ae8 DM	451	return m->llmnr_ipv4_tcp_fd;
	452
	453	fail:
	454	m->llmnr_ipv4_tcp_fd = safe_close(m->llmnr_ipv4_tcp_fd);
	455	return r;
	456	}
	457
	458	int manager_llmnr_ipv6_tcp_fd(Manager *m) {
	459	union sockaddr_union sa = {
	460	.in6.sin6_family = AF_INET6,
22a37591	461	.in6.sin6_port = htobe16(LLMNR_PORT),
5f402ae8 DM	462	};
	463	static const int one = 1;
	464	int r;
	465
	466	assert(m);
	467
	468	if (m->llmnr_ipv6_tcp_fd >= 0)
	469	return m->llmnr_ipv6_tcp_fd;
	470
	471	m->llmnr_ipv6_tcp_fd = socket(AF_INET6, SOCK_STREAM\|SOCK_CLOEXEC\|SOCK_NONBLOCK, 0);
	472	if (m->llmnr_ipv6_tcp_fd < 0)
007ef0a2	473	return log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to create socket: %m");
5f402ae8 DM	474
	475	/* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */
	476	r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &one, sizeof(one));
	477	if (r < 0) {
007ef0a2	478	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_UNICAST_HOPS: %m");
5f402ae8 DM	479	goto fail;
	480	}
	481
	482	r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
	483	if (r < 0) {
007ef0a2	484	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_V6ONLY: %m");
5f402ae8 DM	485	goto fail;
	486	}
	487
	488	r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
	489	if (r < 0) {
007ef0a2	490	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_RECVPKTINFO: %m");
5f402ae8 DM	491	goto fail;
	492	}
	493
	494	r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
	495	if (r < 0) {
007ef0a2	496	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_RECVHOPLIMIT: %m");
5f402ae8 DM	497	goto fail;
	498	}
	499
007ef0a2	500	/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
5f402ae8 DM	501	r = bind(m->llmnr_ipv6_tcp_fd, &sa.sa, sizeof(sa.in6));
5f402ae8 DM	502	if (r < 0) {
007ef0a2 YW	503	if (errno != EADDRINUSE) {
	504	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to bind socket: %m");
	505	goto fail;
	506	}
	507
	508	log_warning("LLMNR-IPv6(TCP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
	509
	510	/* try again with SO_REUSEADDR */
	511	r = setsockopt(m->llmnr_ipv6_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	512	if (r < 0) {
	513	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set SO_REUSEADDR: %m");
	514	goto fail;
	515	}
	516
	517	r = bind(m->llmnr_ipv6_tcp_fd, &sa.sa, sizeof(sa.in6));
	518	if (r < 0) {
	519	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to bind socket: %m");
	520	goto fail;
	521	}
	522	} else {
	523	/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
	524	r = setsockopt(m->llmnr_ipv6_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	525	if (r < 0) {
	526	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set SO_REUSEADDR: %m");
	527	goto fail;
	528	}
5f402ae8 DM	529	}
	530
	531	r = listen(m->llmnr_ipv6_tcp_fd, SOMAXCONN);
	532	if (r < 0) {
007ef0a2	533	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to listen the stream: %m");
5f402ae8 DM	534	goto fail;
	535	}
	536
	537	r = sd_event_add_io(m->event, &m->llmnr_ipv6_tcp_event_source, m->llmnr_ipv6_tcp_fd, EPOLLIN, on_llmnr_stream, m);
ee8d9305	538	if (r < 0)
5f402ae8	539	goto fail;
5f402ae8	540
aa4a9deb LP	541	(void) sd_event_source_set_description(m->llmnr_ipv6_tcp_event_source, "llmnr-ipv6-tcp");
aa4a9deb LP	542
5f402ae8 DM	543	return m->llmnr_ipv6_tcp_fd;
	544
	545	fail:
	546	m->llmnr_ipv6_tcp_fd = safe_close(m->llmnr_ipv6_tcp_fd);
	547	return r;
	548	}