[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>
 ***/

#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, NULL);
        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>
5f402ae8 DM	6	***/
5f402ae8 DM	7
5f402ae8	8	#include <netinet/in.h>
cf0fbc49	9	#include <resolv.h>
5f402ae8	10
3ffd4af2	11	#include "fd-util.h"
5f402ae8	12	#include "resolved-llmnr.h"
3ffd4af2	13	#include "resolved-manager.h"
5f402ae8 DM	14
	15	void manager_llmnr_stop(Manager *m) {
	16	assert(m);
	17
	18	m->llmnr_ipv4_udp_event_source = sd_event_source_unref(m->llmnr_ipv4_udp_event_source);
	19	m->llmnr_ipv4_udp_fd = safe_close(m->llmnr_ipv4_udp_fd);
	20
	21	m->llmnr_ipv6_udp_event_source = sd_event_source_unref(m->llmnr_ipv6_udp_event_source);
	22	m->llmnr_ipv6_udp_fd = safe_close(m->llmnr_ipv6_udp_fd);
	23
	24	m->llmnr_ipv4_tcp_event_source = sd_event_source_unref(m->llmnr_ipv4_tcp_event_source);
	25	m->llmnr_ipv4_tcp_fd = safe_close(m->llmnr_ipv4_tcp_fd);
	26
	27	m->llmnr_ipv6_tcp_event_source = sd_event_source_unref(m->llmnr_ipv6_tcp_event_source);
	28	m->llmnr_ipv6_tcp_fd = safe_close(m->llmnr_ipv6_tcp_fd);
	29	}
	30
	31	int manager_llmnr_start(Manager *m) {
	32	int r;
	33
	34	assert(m);
	35
af49ca27	36	if (m->llmnr_support == RESOLVE_SUPPORT_NO)
5f402ae8 DM	37	return 0;
	38
	39	r = manager_llmnr_ipv4_udp_fd(m);
	40	if (r == -EADDRINUSE)
	41	goto eaddrinuse;
	42	if (r < 0)
	43	return r;
	44
	45	r = manager_llmnr_ipv4_tcp_fd(m);
	46	if (r == -EADDRINUSE)
	47	goto eaddrinuse;
	48	if (r < 0)
	49	return r;
	50
	51	if (socket_ipv6_is_supported()) {
	52	r = manager_llmnr_ipv6_udp_fd(m);
	53	if (r == -EADDRINUSE)
	54	goto eaddrinuse;
	55	if (r < 0)
	56	return r;
	57
	58	r = manager_llmnr_ipv6_tcp_fd(m);
	59	if (r == -EADDRINUSE)
	60	goto eaddrinuse;
	61	if (r < 0)
	62	return r;
	63	}
	64
	65	return 0;
	66
	67	eaddrinuse:
007ef0a2	68	log_warning("Another LLMNR responder prohibits binding the socket to the same port. Turning off LLMNR support.");
af49ca27	69	m->llmnr_support = RESOLVE_SUPPORT_NO;
5f402ae8 DM	70	manager_llmnr_stop(m);
	71
	72	return 0;
	73	}
	74
	75	static int on_llmnr_packet(sd_event_source s, int fd, uint32_t revents, void userdata) {
	76	_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
	77	DnsTransaction *t = NULL;
	78	Manager *m = userdata;
	79	DnsScope *scope;
	80	int r;
	81
b30bf55d LP	82	assert(s);
	83	assert(fd >= 0);
	84	assert(m);
	85
5f402ae8 DM	86	r = manager_recv(m, fd, DNS_PROTOCOL_LLMNR, &p);
	87	if (r <= 0)
	88	return r;
	89
6cae1ebe LP	90	if (manager_our_packet(m, p))
	91	return 0;
	92
5f402ae8	93	scope = manager_find_scope(m, p);
f1b1a5c4 LP	94	if (!scope) {
	95	log_debug("Got LLMNR UDP packet on unknown scope. Ignoring.");
	96	return 0;
	97	}
	98
	99	if (dns_packet_validate_reply(p) > 0) {
b30bf55d	100	log_debug("Got LLMNR UDP reply packet for id %u", DNS_PACKET_ID(p));
5f402ae8 DM	101
	102	dns_scope_check_conflicts(scope, p);
	103
	104	t = hashmap_get(m->dns_transactions, UINT_TO_PTR(DNS_PACKET_ID(p)));
	105	if (t)
	106	dns_transaction_process_reply(t, p);
	107
	108	} else if (dns_packet_validate_query(p) > 0) {
b30bf55d	109	log_debug("Got LLMNR UDP query packet for id %u", DNS_PACKET_ID(p));
5f402ae8 DM	110
	111	dns_scope_process_query(scope, NULL, p);
	112	} else
2c6bf498	113	log_debug("Invalid LLMNR UDP packet, ignoring.");
5f402ae8 DM	114
	115	return 0;
	116	}
	117
	118	int manager_llmnr_ipv4_udp_fd(Manager *m) {
	119	union sockaddr_union sa = {
	120	.in.sin_family = AF_INET,
22a37591	121	.in.sin_port = htobe16(LLMNR_PORT),
5f402ae8 DM	122	};
	123	static const int one = 1, pmtu = IP_PMTUDISC_DONT, ttl = 255;
	124	int r;
	125
	126	assert(m);
	127
	128	if (m->llmnr_ipv4_udp_fd >= 0)
	129	return m->llmnr_ipv4_udp_fd;
	130
	131	m->llmnr_ipv4_udp_fd = socket(AF_INET, SOCK_DGRAM\|SOCK_CLOEXEC\|SOCK_NONBLOCK, 0);
	132	if (m->llmnr_ipv4_udp_fd < 0)
007ef0a2	133	return log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to create socket: %m");
5f402ae8 DM	134
	135	/* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
	136	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl));
	137	if (r < 0) {
007ef0a2	138	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_TTL: %m");
5f402ae8 DM	139	goto fail;
	140	}
	141
	142	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));
	143	if (r < 0) {
007ef0a2	144	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_TTL: %m");
5f402ae8 DM	145	goto fail;
	146	}
	147
	148	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MULTICAST_LOOP, &one, sizeof(one));
	149	if (r < 0) {
007ef0a2	150	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_LOOP: %m");
5f402ae8 DM	151	goto fail;
	152	}
	153
	154	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
	155	if (r < 0) {
007ef0a2	156	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_PKTINFO: %m");
5f402ae8 DM	157	goto fail;
	158	}
	159
	160	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one));
	161	if (r < 0) {
007ef0a2	162	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_RECVTTL: %m");
5f402ae8 DM	163	goto fail;
	164	}
	165
	166	/* Disable Don't-Fragment bit in the IP header */
	167	r = setsockopt(m->llmnr_ipv4_udp_fd, IPPROTO_IP, IP_MTU_DISCOVER, &pmtu, sizeof(pmtu));
	168	if (r < 0) {
007ef0a2	169	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set IP_MTU_DISCOVER: %m");
5f402ae8 DM	170	goto fail;
	171	}
	172
007ef0a2	173	/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
5f402ae8 DM	174	r = bind(m->llmnr_ipv4_udp_fd, &sa.sa, sizeof(sa.in));
5f402ae8 DM	175	if (r < 0) {
007ef0a2 YW	176	if (errno != EADDRINUSE) {
	177	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to bind socket: %m");
	178	goto fail;
	179	}
	180
	181	log_warning("LLMNR-IPv4(UDP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
	182
	183	/* try again with SO_REUSEADDR */
	184	r = setsockopt(m->llmnr_ipv4_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	185	if (r < 0) {
	186	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to set SO_REUSEADDR: %m");
	187	goto fail;
	188	}
	189
	190	r = bind(m->llmnr_ipv4_udp_fd, &sa.sa, sizeof(sa.in));
	191	if (r < 0) {
	192	r = log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to bind socket: %m");
	193	goto fail;
	194	}
	195	} else {
	196	/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
	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	}
5f402ae8 DM	202	}
	203
	204	r = sd_event_add_io(m->event, &m->llmnr_ipv4_udp_event_source, m->llmnr_ipv4_udp_fd, EPOLLIN, on_llmnr_packet, m);
	205	if (r < 0)
	206	goto fail;
	207
aa4a9deb LP	208	(void) sd_event_source_set_description(m->llmnr_ipv4_udp_event_source, "llmnr-ipv4-udp");
aa4a9deb LP	209
5f402ae8 DM	210	return m->llmnr_ipv4_udp_fd;
	211
	212	fail:
	213	m->llmnr_ipv4_udp_fd = safe_close(m->llmnr_ipv4_udp_fd);
	214	return r;
	215	}
	216
	217	int manager_llmnr_ipv6_udp_fd(Manager *m) {
	218	union sockaddr_union sa = {
	219	.in6.sin6_family = AF_INET6,
22a37591	220	.in6.sin6_port = htobe16(LLMNR_PORT),
5f402ae8 DM	221	};
	222	static const int one = 1, ttl = 255;
	223	int r;
	224
	225	assert(m);
	226
	227	if (m->llmnr_ipv6_udp_fd >= 0)
	228	return m->llmnr_ipv6_udp_fd;
	229
	230	m->llmnr_ipv6_udp_fd = socket(AF_INET6, SOCK_DGRAM\|SOCK_CLOEXEC\|SOCK_NONBLOCK, 0);
	231	if (m->llmnr_ipv6_udp_fd < 0)
007ef0a2	232	return log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to create socket: %m");
5f402ae8 DM	233
	234	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl));
	235	if (r < 0) {
007ef0a2	236	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_UNICAST_HOPS: %m");
5f402ae8 DM	237	goto fail;
	238	}
	239
	240	/* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
	241	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl));
	242	if (r < 0) {
007ef0a2	243	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_MULTICAST_HOPS: %m");
5f402ae8 DM	244	goto fail;
	245	}
	246
	247	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &one, sizeof(one));
	248	if (r < 0) {
007ef0a2	249	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_MULTICAST_LOOP: %m");
5f402ae8 DM	250	goto fail;
	251	}
	252
	253	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
	254	if (r < 0) {
007ef0a2	255	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_V6ONLY: %m");
5f402ae8 DM	256	goto fail;
	257	}
	258
	259	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
	260	if (r < 0) {
007ef0a2	261	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_RECVPKTINFO: %m");
5f402ae8 DM	262	goto fail;
	263	}
	264
	265	r = setsockopt(m->llmnr_ipv6_udp_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
	266	if (r < 0) {
007ef0a2	267	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set IPV6_RECVHOPLIMIT: %m");
5f402ae8 DM	268	goto fail;
	269	}
	270
007ef0a2	271	/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
5f402ae8 DM	272	r = bind(m->llmnr_ipv6_udp_fd, &sa.sa, sizeof(sa.in6));
5f402ae8 DM	273	if (r < 0) {
007ef0a2 YW	274	if (errno != EADDRINUSE) {
	275	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to bind socket: %m");
	276	goto fail;
	277	}
	278
	279	log_warning("LLMNR-IPv6(UDP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
	280
	281	/* try again with SO_REUSEADDR */
	282	r = setsockopt(m->llmnr_ipv6_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	283	if (r < 0) {
	284	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to set SO_REUSEADDR: %m");
	285	goto fail;
	286	}
	287
	288	r = bind(m->llmnr_ipv6_udp_fd, &sa.sa, sizeof(sa.in6));
	289	if (r < 0) {
	290	r = log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to bind socket: %m");
	291	goto fail;
	292	}
	293	} else {
	294	/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
	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	}
5f402ae8 DM	300	}
	301
	302	r = sd_event_add_io(m->event, &m->llmnr_ipv6_udp_event_source, m->llmnr_ipv6_udp_fd, EPOLLIN, on_llmnr_packet, m);
35908b98	303	if (r < 0)
5f402ae8	304	goto fail;
5f402ae8	305
aa4a9deb LP	306	(void) sd_event_source_set_description(m->llmnr_ipv6_udp_event_source, "llmnr-ipv6-udp");
aa4a9deb LP	307
5f402ae8 DM	308	return m->llmnr_ipv6_udp_fd;
	309
	310	fail:
	311	m->llmnr_ipv6_udp_fd = safe_close(m->llmnr_ipv6_udp_fd);
	312	return r;
	313	}
	314
	315	static int on_llmnr_stream_packet(DnsStream *s) {
	316	DnsScope *scope;
	317
	318	assert(s);
b30bf55d	319	assert(s->read_packet);
5f402ae8 DM	320
5f402ae8 DM	321	scope = manager_find_scope(s->manager, s->read_packet);
b30bf55d	322	if (!scope)
f1b1a5c4	323	log_debug("Got LLMNR TCP packet on unknown scope. Ignoring.");
b30bf55d LP	324	else if (dns_packet_validate_query(s->read_packet) > 0) {
b30bf55d LP	325	log_debug("Got LLMNR TCP query packet for id %u", DNS_PACKET_ID(s->read_packet));
5f402ae8 DM	326
5f402ae8 DM	327	dns_scope_process_query(scope, s, s->read_packet);
5f402ae8	328	} else
b30bf55d	329	log_debug("Invalid LLMNR TCP packet, ignoring.");
5f402ae8	330
b30bf55d	331	dns_stream_unref(s);
5f402ae8 DM	332	return 0;
	333	}
	334
	335	static int on_llmnr_stream(sd_event_source s, int fd, uint32_t revents, void userdata) {
	336	DnsStream *stream;
	337	Manager *m = userdata;
	338	int cfd, r;
	339
	340	cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK\|SOCK_CLOEXEC);
	341	if (cfd < 0) {
3742095b	342	if (IN_SET(errno, EAGAIN, EINTR))
5f402ae8 DM	343	return 0;
	344
	345	return -errno;
	346	}
	347
91ccab1e	348	r = dns_stream_new(m, &stream, DNS_PROTOCOL_LLMNR, cfd, NULL);
5f402ae8 DM	349	if (r < 0) {
	350	safe_close(cfd);
	351	return r;
	352	}
	353
	354	stream->on_packet = on_llmnr_stream_packet;
	355	return 0;
	356	}
	357
	358	int manager_llmnr_ipv4_tcp_fd(Manager *m) {
	359	union sockaddr_union sa = {
	360	.in.sin_family = AF_INET,
22a37591	361	.in.sin_port = htobe16(LLMNR_PORT),
5f402ae8 DM	362	};
	363	static const int one = 1, pmtu = IP_PMTUDISC_DONT;
	364	int r;
	365
	366	assert(m);
	367
	368	if (m->llmnr_ipv4_tcp_fd >= 0)
	369	return m->llmnr_ipv4_tcp_fd;
	370
	371	m->llmnr_ipv4_tcp_fd = socket(AF_INET, SOCK_STREAM\|SOCK_CLOEXEC\|SOCK_NONBLOCK, 0);
	372	if (m->llmnr_ipv4_tcp_fd < 0)
007ef0a2	373	return log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to create socket: %m");
5f402ae8 DM	374
	375	/* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */
	376	r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_TTL, &one, sizeof(one));
	377	if (r < 0) {
007ef0a2	378	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_TTL: %m");
5f402ae8 DM	379	goto fail;
	380	}
	381
	382	r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
	383	if (r < 0) {
007ef0a2	384	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_PKTINFO: %m");
5f402ae8 DM	385	goto fail;
	386	}
	387
	388	r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one));
	389	if (r < 0) {
007ef0a2	390	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_RECVTTL: %m");
5f402ae8 DM	391	goto fail;
	392	}
	393
	394	/* Disable Don't-Fragment bit in the IP header */
	395	r = setsockopt(m->llmnr_ipv4_tcp_fd, IPPROTO_IP, IP_MTU_DISCOVER, &pmtu, sizeof(pmtu));
	396	if (r < 0) {
007ef0a2	397	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set IP_MTU_DISCOVER: %m");
5f402ae8 DM	398	goto fail;
	399	}
	400
007ef0a2	401	/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
5f402ae8 DM	402	r = bind(m->llmnr_ipv4_tcp_fd, &sa.sa, sizeof(sa.in));
5f402ae8 DM	403	if (r < 0) {
007ef0a2 YW	404	if (errno != EADDRINUSE) {
	405	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to bind socket: %m");
	406	goto fail;
	407	}
	408
	409	log_warning("LLMNR-IPv4(TCP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
	410
	411	/* try again with SO_REUSEADDR */
	412	r = setsockopt(m->llmnr_ipv4_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	413	if (r < 0) {
	414	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to set SO_REUSEADDR: %m");
	415	goto fail;
	416	}
	417
	418	r = bind(m->llmnr_ipv4_tcp_fd, &sa.sa, sizeof(sa.in));
	419	if (r < 0) {
	420	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to bind socket: %m");
	421	goto fail;
	422	}
	423	} else {
	424	/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
	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	}
5f402ae8 DM	430	}
	431
	432	r = listen(m->llmnr_ipv4_tcp_fd, SOMAXCONN);
	433	if (r < 0) {
007ef0a2	434	r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to listen the stream: %m");
5f402ae8 DM	435	goto fail;
	436	}
	437
	438	r = sd_event_add_io(m->event, &m->llmnr_ipv4_tcp_event_source, m->llmnr_ipv4_tcp_fd, EPOLLIN, on_llmnr_stream, m);
	439	if (r < 0)
	440	goto fail;
	441
aa4a9deb LP	442	(void) sd_event_source_set_description(m->llmnr_ipv4_tcp_event_source, "llmnr-ipv4-tcp");
aa4a9deb LP	443
5f402ae8 DM	444	return m->llmnr_ipv4_tcp_fd;
	445
	446	fail:
	447	m->llmnr_ipv4_tcp_fd = safe_close(m->llmnr_ipv4_tcp_fd);
	448	return r;
	449	}
	450
	451	int manager_llmnr_ipv6_tcp_fd(Manager *m) {
	452	union sockaddr_union sa = {
	453	.in6.sin6_family = AF_INET6,
22a37591	454	.in6.sin6_port = htobe16(LLMNR_PORT),
5f402ae8 DM	455	};
	456	static const int one = 1;
	457	int r;
	458
	459	assert(m);
	460
	461	if (m->llmnr_ipv6_tcp_fd >= 0)
	462	return m->llmnr_ipv6_tcp_fd;
	463
	464	m->llmnr_ipv6_tcp_fd = socket(AF_INET6, SOCK_STREAM\|SOCK_CLOEXEC\|SOCK_NONBLOCK, 0);
	465	if (m->llmnr_ipv6_tcp_fd < 0)
007ef0a2	466	return log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to create socket: %m");
5f402ae8 DM	467
	468	/* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */
	469	r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &one, sizeof(one));
	470	if (r < 0) {
007ef0a2	471	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_UNICAST_HOPS: %m");
5f402ae8 DM	472	goto fail;
	473	}
	474
	475	r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
	476	if (r < 0) {
007ef0a2	477	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_V6ONLY: %m");
5f402ae8 DM	478	goto fail;
	479	}
	480
	481	r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
	482	if (r < 0) {
007ef0a2	483	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_RECVPKTINFO: %m");
5f402ae8 DM	484	goto fail;
	485	}
	486
	487	r = setsockopt(m->llmnr_ipv6_tcp_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
	488	if (r < 0) {
007ef0a2	489	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set IPV6_RECVHOPLIMIT: %m");
5f402ae8 DM	490	goto fail;
	491	}
	492
007ef0a2	493	/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
5f402ae8 DM	494	r = bind(m->llmnr_ipv6_tcp_fd, &sa.sa, sizeof(sa.in6));
5f402ae8 DM	495	if (r < 0) {
007ef0a2 YW	496	if (errno != EADDRINUSE) {
	497	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to bind socket: %m");
	498	goto fail;
	499	}
	500
	501	log_warning("LLMNR-IPv6(TCP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
	502
	503	/* try again with SO_REUSEADDR */
	504	r = setsockopt(m->llmnr_ipv6_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
	505	if (r < 0) {
	506	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to set SO_REUSEADDR: %m");
	507	goto fail;
	508	}
	509
	510	r = bind(m->llmnr_ipv6_tcp_fd, &sa.sa, sizeof(sa.in6));
	511	if (r < 0) {
	512	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to bind socket: %m");
	513	goto fail;
	514	}
	515	} else {
	516	/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
	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	}
5f402ae8 DM	522	}
	523
	524	r = listen(m->llmnr_ipv6_tcp_fd, SOMAXCONN);
	525	if (r < 0) {
007ef0a2	526	r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to listen the stream: %m");
5f402ae8 DM	527	goto fail;
	528	}
	529
	530	r = sd_event_add_io(m->event, &m->llmnr_ipv6_tcp_event_source, m->llmnr_ipv6_tcp_fd, EPOLLIN, on_llmnr_stream, m);
ee8d9305	531	if (r < 0)
5f402ae8	532	goto fail;
5f402ae8	533
aa4a9deb LP	534	(void) sd_event_source_set_description(m->llmnr_ipv6_tcp_event_source, "llmnr-ipv6-tcp");
aa4a9deb LP	535
5f402ae8 DM	536	return m->llmnr_ipv6_tcp_fd;
	537
	538	fail:
	539	m->llmnr_ipv6_tcp_fd = safe_close(m->llmnr_ipv6_tcp_fd);
	540	return r;
	541	}