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

/***
  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
5f402ae8 DM	1	/***
	2	This file is part of systemd.
	3
	4	Copyright 2014 Tom Gundersen <teg@jklm.no>
	5
	6	systemd is free software; you can redistribute it and/or modify it
	7	under the terms of the GNU Lesser General Public License as published by
	8	the Free Software Foundation; either version 2.1 of the License, or
	9	(at your option) any later version.
	10
	11	systemd is distributed in the hope that it will be useful, but
	12	WITHOUT ANY WARRANTY; without even the implied warranty of
	13	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	14	Lesser General Public License for more details.
	15
	16	You should have received a copy of the GNU Lesser General Public License
	17	along with systemd; If not, see <http://www.gnu.org/licenses/>.
	18	***/
	19
5f402ae8	20	#include <netinet/in.h>
cf0fbc49	21	#include <resolv.h>
5f402ae8	22
3ffd4af2	23	#include "fd-util.h"
5f402ae8	24	#include "resolved-llmnr.h"
3ffd4af2	25	#include "resolved-manager.h"
5f402ae8 DM	26
	27	void manager_llmnr_stop(Manager *m) {
	28	assert(m);
	29
	30	m->llmnr_ipv4_udp_event_source = sd_event_source_unref(m->llmnr_ipv4_udp_event_source);
	31	m->llmnr_ipv4_udp_fd = safe_close(m->llmnr_ipv4_udp_fd);
	32
	33	m->llmnr_ipv6_udp_event_source = sd_event_source_unref(m->llmnr_ipv6_udp_event_source);
	34	m->llmnr_ipv6_udp_fd = safe_close(m->llmnr_ipv6_udp_fd);
	35
	36	m->llmnr_ipv4_tcp_event_source = sd_event_source_unref(m->llmnr_ipv4_tcp_event_source);
	37	m->llmnr_ipv4_tcp_fd = safe_close(m->llmnr_ipv4_tcp_fd);
	38
	39	m->llmnr_ipv6_tcp_event_source = sd_event_source_unref(m->llmnr_ipv6_tcp_event_source);
	40	m->llmnr_ipv6_tcp_fd = safe_close(m->llmnr_ipv6_tcp_fd);
	41	}
	42
	43	int manager_llmnr_start(Manager *m) {
	44	int r;
	45
	46	assert(m);
	47
af49ca27	48	if (m->llmnr_support == RESOLVE_SUPPORT_NO)
5f402ae8 DM	49	return 0;
	50
	51	r = manager_llmnr_ipv4_udp_fd(m);
	52	if (r == -EADDRINUSE)
	53	goto eaddrinuse;
	54	if (r < 0)
	55	return r;
	56
	57	r = manager_llmnr_ipv4_tcp_fd(m);
	58	if (r == -EADDRINUSE)
	59	goto eaddrinuse;
	60	if (r < 0)
	61	return r;
	62
	63	if (socket_ipv6_is_supported()) {
	64	r = manager_llmnr_ipv6_udp_fd(m);
	65	if (r == -EADDRINUSE)
	66	goto eaddrinuse;
	67	if (r < 0)
	68	return r;
	69
	70	r = manager_llmnr_ipv6_tcp_fd(m);
	71	if (r == -EADDRINUSE)
	72	goto eaddrinuse;
	73	if (r < 0)
	74	return r;
	75	}
	76
	77	return 0;
	78
	79	eaddrinuse:
007ef0a2	80	log_warning("Another LLMNR responder prohibits binding the socket to the same port. Turning off LLMNR support.");
af49ca27	81	m->llmnr_support = RESOLVE_SUPPORT_NO;
5f402ae8 DM	82	manager_llmnr_stop(m);
	83
	84	return 0;
	85	}
	86
	87	static int on_llmnr_packet(sd_event_source s, int fd, uint32_t revents, void userdata) {
	88	_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
	89	DnsTransaction *t = NULL;
	90	Manager *m = userdata;
	91	DnsScope *scope;
	92	int r;
	93
b30bf55d LP	94	assert(s);
	95	assert(fd >= 0);
	96	assert(m);
	97
5f402ae8 DM	98	r = manager_recv(m, fd, DNS_PROTOCOL_LLMNR, &p);
	99	if (r <= 0)
	100	return r;
	101
	102	scope = manager_find_scope(m, p);
b30bf55d	103	if (!scope)
5f402ae8	104	log_warning("Got LLMNR UDP packet on unknown scope. Ignoring.");
b30bf55d LP	105	else if (dns_packet_validate_reply(p) > 0) {
b30bf55d LP	106	log_debug("Got LLMNR UDP reply packet for id %u", DNS_PACKET_ID(p));
5f402ae8 DM	107
	108	dns_scope_check_conflicts(scope, p);
	109
	110	t = hashmap_get(m->dns_transactions, UINT_TO_PTR(DNS_PACKET_ID(p)));
	111	if (t)
	112	dns_transaction_process_reply(t, p);
	113
	114	} else if (dns_packet_validate_query(p) > 0) {
b30bf55d	115	log_debug("Got LLMNR UDP query packet for id %u", DNS_PACKET_ID(p));
5f402ae8 DM	116
	117	dns_scope_process_query(scope, NULL, p);
	118	} else
2c6bf498	119	log_debug("Invalid LLMNR UDP packet, ignoring.");
5f402ae8 DM	120
	121	return 0;
	122	}
	123
	124	int manager_llmnr_ipv4_udp_fd(Manager *m) {
	125	union sockaddr_union sa = {
	126	.in.sin_family = AF_INET,
22a37591	127	.in.sin_port = htobe16(LLMNR_PORT),
5f402ae8 DM	128	};
	129	static const int one = 1, pmtu = IP_PMTUDISC_DONT, ttl = 255;
	130	int r;
	131
	132	assert(m);
	133
	134	if (m->llmnr_ipv4_udp_fd >= 0)
	135	return m->llmnr_ipv4_udp_fd;
	136
	137	m->llmnr_ipv4_udp_fd = socket(AF_INET, SOCK_DGRAM\|SOCK_CLOEXEC\|SOCK_NONBLOCK, 0);
	138	if (m->llmnr_ipv4_udp_fd < 0)
007ef0a2	139	return log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to create socket: %m");
5f402ae8 DM	140
	141	/* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
	142	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl));
	143	if (r < 0) {
007ef0a2	144	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_TTL: %m");
5f402ae8 DM	145	goto fail;
	146	}
	147
	148	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));
	149	if (r < 0) {
007ef0a2	150	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_TTL: %m");
5f402ae8 DM	151	goto fail;
	152	}
	153
	154	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_LOOP, &one, sizeof(one));
	155	if (r < 0) {
007ef0a2	156	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_LOOP: %m");
5f402ae8 DM	157	goto fail;
	158	}
	159
	160	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
	161	if (r < 0) {
007ef0a2	162	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_PKTINFO: %m");
5f402ae8 DM	163	goto fail;
	164	}
	165
	166	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one));
	167	if (r < 0) {
007ef0a2	168	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_RECVTTL: %m");
5f402ae8 DM	169	goto fail;
	170	}
	171
	172	/* Disable Don't-Fragment bit in the IP header */
	173	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MTU_DISCOVER, &pmtu, sizeof(pmtu));
	174	if (r < 0) {
007ef0a2	175	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_MTU_DISCOVER: %m");
5f402ae8 DM	176	goto fail;
	177	}
	178
007ef0a2	179	/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
5f402ae8 DM	180	r = bind(m->llmnr_ipv4_udp_fd, &sa.sa, sizeof(sa.in));
5f402ae8 DM	181	if (r < 0) {
007ef0a2 YW	182	if (errno != EADDRINUSE) {
	183	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to bind socket: %m");
	184	goto fail;
	185	}
	186
	187	log_warning("LLMNR-IPv4(UDP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
	188
	189	/* try again with SO_REUSEADDR */
	190	r = setsockopt(m->llmnr_ipv4_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	191	if (r < 0) {
	192	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set SO_REUSEADDR: %m");
	193	goto fail;
	194	}
	195
	196	r = bind(m->llmnr_ipv4_udp_fd, &sa.sa, sizeof(sa.in));
	197	if (r < 0) {
	198	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to bind socket: %m");
	199	goto fail;
	200	}
	201	} else {
	202	/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
	203	r = setsockopt(m->llmnr_ipv4_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	204	if (r < 0) {
	205	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set SO_REUSEADDR: %m");
	206	goto fail;
	207	}
5f402ae8 DM	208	}
	209
	210	r = sd_event_add_io(m->event, &m->llmnr_ipv4_udp_event_source, m->llmnr_ipv4_udp_fd, EPOLLIN, on_llmnr_packet, m);
	211	if (r < 0)
	212	goto fail;
	213
aa4a9deb LP	214	(void) sd_event_source_set_description(m->llmnr_ipv4_udp_event_source, "llmnr-ipv4-udp");
aa4a9deb LP	215
5f402ae8 DM	216	return m->llmnr_ipv4_udp_fd;
	217
	218	fail:
	219	m->llmnr_ipv4_udp_fd = safe_close(m->llmnr_ipv4_udp_fd);
	220	return r;
	221	}
	222
	223	int manager_llmnr_ipv6_udp_fd(Manager *m) {
	224	union sockaddr_union sa = {
	225	.in6.sin6_family = AF_INET6,
22a37591	226	.in6.sin6_port = htobe16(LLMNR_PORT),
5f402ae8 DM	227	};
	228	static const int one = 1, ttl = 255;
	229	int r;
	230
	231	assert(m);
	232
	233	if (m->llmnr_ipv6_udp_fd >= 0)
	234	return m->llmnr_ipv6_udp_fd;
	235
	236	m->llmnr_ipv6_udp_fd = socket(AF_INET6, SOCK_DGRAM\|SOCK_CLOEXEC\|SOCK_NONBLOCK, 0);
	237	if (m->llmnr_ipv6_udp_fd < 0)
007ef0a2	238	return log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to create socket: %m");
5f402ae8 DM	239
	240	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl));
	241	if (r < 0) {
007ef0a2	242	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_UNICAST_HOPS: %m");
5f402ae8 DM	243	goto fail;
	244	}
	245
	246	/* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
	247	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl));
	248	if (r < 0) {
007ef0a2	249	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_MULTICAST_HOPS: %m");
5f402ae8 DM	250	goto fail;
	251	}
	252
	253	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &one, sizeof(one));
	254	if (r < 0) {
007ef0a2	255	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_MULTICAST_LOOP: %m");
5f402ae8 DM	256	goto fail;
	257	}
	258
	259	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
	260	if (r < 0) {
007ef0a2	261	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_V6ONLY: %m");
5f402ae8 DM	262	goto fail;
	263	}
	264
	265	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
	266	if (r < 0) {
007ef0a2	267	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_RECVPKTINFO: %m");
5f402ae8 DM	268	goto fail;
	269	}
	270
	271	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
	272	if (r < 0) {
007ef0a2	273	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_RECVHOPLIMIT: %m");
5f402ae8 DM	274	goto fail;
	275	}
	276
007ef0a2	277	/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
5f402ae8 DM	278	r = bind(m->llmnr_ipv6_udp_fd, &sa.sa, sizeof(sa.in6));
5f402ae8 DM	279	if (r < 0) {
007ef0a2 YW	280	if (errno != EADDRINUSE) {
	281	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to bind socket: %m");
	282	goto fail;
	283	}
	284
	285	log_warning("LLMNR-IPv6(UDP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
	286
	287	/* try again with SO_REUSEADDR */
	288	r = setsockopt(m->llmnr_ipv6_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	289	if (r < 0) {
	290	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set SO_REUSEADDR: %m");
	291	goto fail;
	292	}
	293
	294	r = bind(m->llmnr_ipv6_udp_fd, &sa.sa, sizeof(sa.in6));
	295	if (r < 0) {
	296	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to bind socket: %m");
	297	goto fail;
	298	}
	299	} else {
	300	/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
	301	r = setsockopt(m->llmnr_ipv6_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	302	if (r < 0) {
	303	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set SO_REUSEADDR: %m");
	304	goto fail;
	305	}
5f402ae8 DM	306	}
	307
	308	r = sd_event_add_io(m->event, &m->llmnr_ipv6_udp_event_source, m->llmnr_ipv6_udp_fd, EPOLLIN, on_llmnr_packet, m);
35908b98	309	if (r < 0)
5f402ae8	310	goto fail;
5f402ae8	311
aa4a9deb LP	312	(void) sd_event_source_set_description(m->llmnr_ipv6_udp_event_source, "llmnr-ipv6-udp");
aa4a9deb LP	313
5f402ae8 DM	314	return m->llmnr_ipv6_udp_fd;
	315
	316	fail:
	317	m->llmnr_ipv6_udp_fd = safe_close(m->llmnr_ipv6_udp_fd);
	318	return r;
	319	}
	320
	321	static int on_llmnr_stream_packet(DnsStream *s) {
	322	DnsScope *scope;
	323
	324	assert(s);
b30bf55d	325	assert(s->read_packet);
5f402ae8 DM	326
5f402ae8 DM	327	scope = manager_find_scope(s->manager, s->read_packet);
b30bf55d	328	if (!scope)
0ea929d5	329	log_warning("Got LLMNR TCP packet on unknown scope. Ignoring.");
b30bf55d LP	330	else if (dns_packet_validate_query(s->read_packet) > 0) {
b30bf55d LP	331	log_debug("Got LLMNR TCP query packet for id %u", DNS_PACKET_ID(s->read_packet));
5f402ae8 DM	332
5f402ae8 DM	333	dns_scope_process_query(scope, s, s->read_packet);
5f402ae8	334	} else
b30bf55d	335	log_debug("Invalid LLMNR TCP packet, ignoring.");
5f402ae8	336
b30bf55d	337	dns_stream_unref(s);
5f402ae8 DM	338	return 0;
	339	}
	340
	341	static int on_llmnr_stream(sd_event_source s, int fd, uint32_t revents, void userdata) {
	342	DnsStream *stream;
	343	Manager *m = userdata;
	344	int cfd, r;
	345
	346	cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK\|SOCK_CLOEXEC);
	347	if (cfd < 0) {
3742095b	348	if (IN_SET(errno, EAGAIN, EINTR))
5f402ae8 DM	349	return 0;
	350
	351	return -errno;
	352	}
	353
	354	r = dns_stream_new(m, &stream, DNS_PROTOCOL_LLMNR, cfd);
	355	if (r < 0) {
	356	safe_close(cfd);
	357	return r;
	358	}
	359
	360	stream->on_packet = on_llmnr_stream_packet;
	361	return 0;
	362	}
	363
	364	int manager_llmnr_ipv4_tcp_fd(Manager *m) {
	365	union sockaddr_union sa = {
	366	.in.sin_family = AF_INET,
22a37591	367	.in.sin_port = htobe16(LLMNR_PORT),
5f402ae8 DM	368	};
	369	static const int one = 1, pmtu = IP_PMTUDISC_DONT;
	370	int r;
	371
	372	assert(m);
	373
	374	if (m->llmnr_ipv4_tcp_fd >= 0)
	375	return m->llmnr_ipv4_tcp_fd;
	376
	377	m->llmnr_ipv4_tcp_fd = socket(AF_INET, SOCK_STREAM\|SOCK_CLOEXEC\|SOCK_NONBLOCK, 0);
	378	if (m->llmnr_ipv4_tcp_fd < 0)
007ef0a2	379	return log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to create socket: %m");
5f402ae8 DM	380
	381	/* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */
	382	r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_TTL, &one, sizeof(one));
	383	if (r < 0) {
007ef0a2	384	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_TTL: %m");
5f402ae8 DM	385	goto fail;
	386	}
	387
	388	r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
	389	if (r < 0) {
007ef0a2	390	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_PKTINFO: %m");
5f402ae8 DM	391	goto fail;
	392	}
	393
	394	r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one));
	395	if (r < 0) {
007ef0a2	396	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_RECVTTL: %m");
5f402ae8 DM	397	goto fail;
	398	}
	399
	400	/* Disable Don't-Fragment bit in the IP header */
	401	r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_MTU_DISCOVER, &pmtu, sizeof(pmtu));
	402	if (r < 0) {
007ef0a2	403	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_MTU_DISCOVER: %m");
5f402ae8 DM	404	goto fail;
	405	}
	406
007ef0a2	407	/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
5f402ae8 DM	408	r = bind(m->llmnr_ipv4_tcp_fd, &sa.sa, sizeof(sa.in));
5f402ae8 DM	409	if (r < 0) {
007ef0a2 YW	410	if (errno != EADDRINUSE) {
	411	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to bind socket: %m");
	412	goto fail;
	413	}
	414
	415	log_warning("LLMNR-IPv4(TCP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
	416
	417	/* try again with SO_REUSEADDR */
	418	r = setsockopt(m->llmnr_ipv4_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	419	if (r < 0) {
	420	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set SO_REUSEADDR: %m");
	421	goto fail;
	422	}
	423
	424	r = bind(m->llmnr_ipv4_tcp_fd, &sa.sa, sizeof(sa.in));
	425	if (r < 0) {
	426	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to bind socket: %m");
	427	goto fail;
	428	}
	429	} else {
	430	/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
	431	r = setsockopt(m->llmnr_ipv4_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	432	if (r < 0) {
	433	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set SO_REUSEADDR: %m");
	434	goto fail;
	435	}
5f402ae8 DM	436	}
	437
	438	r = listen(m->llmnr_ipv4_tcp_fd, SOMAXCONN);
	439	if (r < 0) {
007ef0a2	440	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to listen the stream: %m");
5f402ae8 DM	441	goto fail;
	442	}
	443
	444	r = sd_event_add_io(m->event, &m->llmnr_ipv4_tcp_event_source, m->llmnr_ipv4_tcp_fd, EPOLLIN, on_llmnr_stream, m);
	445	if (r < 0)
	446	goto fail;
	447
aa4a9deb LP	448	(void) sd_event_source_set_description(m->llmnr_ipv4_tcp_event_source, "llmnr-ipv4-tcp");
aa4a9deb LP	449
5f402ae8 DM	450	return m->llmnr_ipv4_tcp_fd;
	451
	452	fail:
	453	m->llmnr_ipv4_tcp_fd = safe_close(m->llmnr_ipv4_tcp_fd);
	454	return r;
	455	}
	456
	457	int manager_llmnr_ipv6_tcp_fd(Manager *m) {
	458	union sockaddr_union sa = {
	459	.in6.sin6_family = AF_INET6,
22a37591	460	.in6.sin6_port = htobe16(LLMNR_PORT),
5f402ae8 DM	461	};
	462	static const int one = 1;
	463	int r;
	464
	465	assert(m);
	466
	467	if (m->llmnr_ipv6_tcp_fd >= 0)
	468	return m->llmnr_ipv6_tcp_fd;
	469
	470	m->llmnr_ipv6_tcp_fd = socket(AF_INET6, SOCK_STREAM\|SOCK_CLOEXEC\|SOCK_NONBLOCK, 0);
	471	if (m->llmnr_ipv6_tcp_fd < 0)
007ef0a2	472	return log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to create socket: %m");
5f402ae8 DM	473
	474	/* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */
	475	r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &one, sizeof(one));
	476	if (r < 0) {
007ef0a2	477	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_UNICAST_HOPS: %m");
5f402ae8 DM	478	goto fail;
	479	}
	480
	481	r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
	482	if (r < 0) {
007ef0a2	483	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_V6ONLY: %m");
5f402ae8 DM	484	goto fail;
	485	}
	486
	487	r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
	488	if (r < 0) {
007ef0a2	489	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_RECVPKTINFO: %m");
5f402ae8 DM	490	goto fail;
	491	}
	492
	493	r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
	494	if (r < 0) {
007ef0a2	495	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_RECVHOPLIMIT: %m");
5f402ae8 DM	496	goto fail;
	497	}
	498
007ef0a2	499	/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
5f402ae8 DM	500	r = bind(m->llmnr_ipv6_tcp_fd, &sa.sa, sizeof(sa.in6));
5f402ae8 DM	501	if (r < 0) {
007ef0a2 YW	502	if (errno != EADDRINUSE) {
	503	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to bind socket: %m");
	504	goto fail;
	505	}
	506
	507	log_warning("LLMNR-IPv6(TCP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
	508
	509	/* try again with SO_REUSEADDR */
	510	r = setsockopt(m->llmnr_ipv6_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	511	if (r < 0) {
	512	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set SO_REUSEADDR: %m");
	513	goto fail;
	514	}
	515
	516	r = bind(m->llmnr_ipv6_tcp_fd, &sa.sa, sizeof(sa.in6));
	517	if (r < 0) {
	518	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to bind socket: %m");
	519	goto fail;
	520	}
	521	} else {
	522	/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
	523	r = setsockopt(m->llmnr_ipv6_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	524	if (r < 0) {
	525	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set SO_REUSEADDR: %m");
	526	goto fail;
	527	}
5f402ae8 DM	528	}
	529
	530	r = listen(m->llmnr_ipv6_tcp_fd, SOMAXCONN);
	531	if (r < 0) {
007ef0a2	532	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to listen the stream: %m");
5f402ae8 DM	533	goto fail;
	534	}
	535
	536	r = sd_event_add_io(m->event, &m->llmnr_ipv6_tcp_event_source, m->llmnr_ipv6_tcp_fd, EPOLLIN, on_llmnr_stream, m);
ee8d9305	537	if (r < 0)
5f402ae8	538	goto fail;
5f402ae8	539
aa4a9deb LP	540	(void) sd_event_source_set_description(m->llmnr_ipv6_tcp_event_source, "llmnr-ipv6-tcp");
aa4a9deb LP	541
5f402ae8 DM	542	return m->llmnr_ipv6_tcp_fd;
	543
	544	fail:
	545	m->llmnr_ipv6_tcp_fd = safe_close(m->llmnr_ipv6_tcp_fd);
	546	return r;
	547	}