From c6a8f6f66da111a417cef7be81ceb9a8f336e541 Mon Sep 17 00:00:00 2001 From: Yu Watanabe Date: Thu, 16 Mar 2017 15:52:34 +0900 Subject: [PATCH 1/4] resolved: do not start LLMNR or mDNS stack when no network enables them When no network enables LLMNR or mDNS, it is not necessary to create LLMNR or mDNS related sockets. So, let's create them only when LLMNR- or mDNS-enabled network becomes active or at least one network enables `LLMNR=` or `MulticastDNS=` options. --- src/resolve/resolved-link.c | 17 +++++++++++++++++ src/resolve/resolved-manager.c | 8 -------- 2 files changed, 17 insertions(+), 8 deletions(-) diff --git a/src/resolve/resolved-link.c b/src/resolve/resolved-link.c index 3f7f9035cf..d06096f3f2 100644 --- a/src/resolve/resolved-link.c +++ b/src/resolve/resolved-link.c @@ -28,6 +28,8 @@ #include "mkdir.h" #include "parse-util.h" #include "resolved-link.h" +#include "resolved-llmnr.h" +#include "resolved-mdns.h" #include "string-util.h" #include "strv.h" @@ -523,10 +525,25 @@ static void link_read_settings(Link *l) { } int link_update(Link *l) { + int r; + assert(l); link_read_settings(l); link_load_user(l); + + if (l->llmnr_support != RESOLVE_SUPPORT_NO) { + r = manager_llmnr_start(l->manager); + if (r < 0) + return r; + } + + if (l->mdns_support != RESOLVE_SUPPORT_NO) { + r = manager_mdns_start(l->manager); + if (r < 0) + return r; + } + link_allocate_scopes(l); link_add_rrs(l, false); diff --git a/src/resolve/resolved-manager.c b/src/resolve/resolved-manager.c index c4e4409fe3..9db8b8f616 100644 --- a/src/resolve/resolved-manager.c +++ b/src/resolve/resolved-manager.c @@ -612,14 +612,6 @@ int manager_start(Manager *m) { if (r < 0) return r; - r = manager_llmnr_start(m); - if (r < 0) - return r; - - r = manager_mdns_start(m); - if (r < 0) - return r; - return 0; } From 71a047d2f7ca37bb8e20e94622e94240f8812649 Mon Sep 17 00:00:00 2001 From: Yu Watanabe Date: Tue, 21 Mar 2017 13:34:52 +0900 Subject: [PATCH 2/4] resolved: detect and warn other running mDNS stack Previously, `SO_REUSEADDR` is set before `bind`-ing socket, Thus, even if another mDNS stack (e.g. avahi) is running, `bind` always success and we cannot detect the other stack. By this commit, we first try to `bind` without `SO_REUSEADDR`, and if it fails, show warning and retry with `SO_REUSEADDR`. --- src/resolve/resolved-mdns.c | 102 +++++++++++++++++++++++++----------- 1 file changed, 71 insertions(+), 31 deletions(-) diff --git a/src/resolve/resolved-mdns.c b/src/resolve/resolved-mdns.c index c40e8f75f0..415dc1a532 100644 --- a/src/resolve/resolved-mdns.c +++ b/src/resolve/resolved-mdns.c @@ -60,7 +60,7 @@ int manager_mdns_start(Manager *m) { return 0; eaddrinuse: - log_warning("There appears to be another mDNS responder running. Turning off mDNS support."); + log_warning("Another mDNS responder prohibits binding the socket to the same port. Turning off mDNS support."); m->mdns_support = RESOLVE_SUPPORT_NO; manager_mdns_stop(m); @@ -217,55 +217,75 @@ int manager_mdns_ipv4_fd(Manager *m) { m->mdns_ipv4_fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); if (m->mdns_ipv4_fd < 0) - return -errno; + return log_error_errno(errno, "mDNS-IPv4: Failed to create socket: %m"); r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl)); if (r < 0) { - r = -errno; + r = log_error_errno(errno, "mDNS-IPv4: Failed to set IP_TTL: %m"); goto fail; } r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)); if (r < 0) { - r = -errno; + r = log_error_errno(errno, "mDNS-IPv4: Failed to set IP_MULTICAST_TTL: %m"); goto fail; } r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_MULTICAST_LOOP, &one, sizeof(one)); if (r < 0) { - r = -errno; - goto fail; - } - - r = setsockopt(m->mdns_ipv4_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)); - if (r < 0) { - r = -errno; + r = log_error_errno(errno, "mDNS-IPv4: Failed to set IP_MULTICAST_LOOP: %m"); goto fail; } r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one)); if (r < 0) { - r = -errno; + r = log_error_errno(errno, "mDNS-IPv4: Failed to set IP_PKTINFO: %m"); goto fail; } r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one)); if (r < 0) { - r = -errno; + r = log_error_errno(errno, "mDNS-IPv4: Failed to set IP_RECVTTL: %m"); goto fail; } /* Disable Don't-Fragment bit in the IP header */ r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_MTU_DISCOVER, &pmtu, sizeof(pmtu)); if (r < 0) { - r = -errno; + r = log_error_errno(errno, "mDNS-IPv4: Failed to set IP_MTU_DISCOVER: %m"); goto fail; } + /* See the section 15.1 of RFC6762 */ + /* first try to bind without SO_REUSEADDR to detect another mDNS responder */ r = bind(m->mdns_ipv4_fd, &sa.sa, sizeof(sa.in)); if (r < 0) { - r = -errno; - goto fail; + if (errno != EADDRINUSE) { + r = log_error_errno(errno, "mDNS-IPv4: Failed to bind socket: %m"); + goto fail; + } + + log_warning("mDNS-IPv4: There appears to be another mDNS responder running, or previously systemd-resolved crashed with some outstanding transfers."); + + /* try again with SO_REUSEADDR */ + r = setsockopt(m->mdns_ipv4_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)); + if (r < 0) { + r = log_error_errno(errno, "mDNS-IPv4: Failed to set SO_REUSEADDR: %m"); + goto fail; + } + + r = bind(m->mdns_ipv4_fd, &sa.sa, sizeof(sa.in)); + if (r < 0) { + r = log_error_errno(errno, "mDNS-IPv4: Failed to bind socket: %m"); + goto fail; + } + } else { + /* enable SO_REUSEADDR for the case that the user really wants multiple mDNS responders */ + r = setsockopt(m->mdns_ipv4_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)); + if (r < 0) { + r = log_error_errno(errno, "mDNS-IPv4: Failed to set SO_REUSEADDR: %m"); + goto fail; + } } r = sd_event_add_io(m->event, &m->mdns_ipv4_event_source, m->mdns_ipv4_fd, EPOLLIN, on_mdns_packet, m); @@ -294,55 +314,75 @@ int manager_mdns_ipv6_fd(Manager *m) { m->mdns_ipv6_fd = socket(AF_INET6, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); if (m->mdns_ipv6_fd < 0) - return -errno; + return log_error_errno(errno, "mDNS-IPv6: Failed to create socket: %m"); r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl)); if (r < 0) { - r = -errno; + r = log_error_errno(errno, "mDNS-IPv6: 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->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl)); if (r < 0) { - r = -errno; + r = log_error_errno(errno, "mDNS-IPv6: Failed to set IPV6_MULTICAST_HOPS: %m"); goto fail; } r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &one, sizeof(one)); if (r < 0) { - r = -errno; + r = log_error_errno(errno, "mDNS-IPv6: Failed to set IPV6_MULTICAST_LOOP: %m"); goto fail; } r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one)); if (r < 0) { - r = -errno; - goto fail; - } - - r = setsockopt(m->mdns_ipv6_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)); - if (r < 0) { - r = -errno; + r = log_error_errno(errno, "mDNS-IPv6: Failed to set IPV6_V6ONLY: %m"); goto fail; } r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one)); if (r < 0) { - r = -errno; + r = log_error_errno(errno, "mDNS-IPv6: Failed to set IPV6_RECVPKTINFO: %m"); goto fail; } r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one)); if (r < 0) { - r = -errno; + r = log_error_errno(errno, "mDNS-IPv6: Failed to set IPV6_RECVHOPLIMIT: %m"); goto fail; } + /* See the section 15.1 of RFC6762 */ + /* first try to bind without SO_REUSEADDR to detect another mDNS responder */ r = bind(m->mdns_ipv6_fd, &sa.sa, sizeof(sa.in6)); if (r < 0) { - r = -errno; - goto fail; + if (errno != EADDRINUSE) { + r = log_error_errno(errno, "mDNS-IPv6: Failed to bind socket: %m"); + goto fail; + } + + log_warning("mDNS-IPv6: There appears to be another mDNS responder running, or previously systemd-resolved crashed with some outstanding transfers."); + + /* try again with SO_REUSEADDR */ + r = setsockopt(m->mdns_ipv6_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)); + if (r < 0) { + r = log_error_errno(errno, "mDNS-IPv6: Failed to set SO_REUSEADDR: %m"); + goto fail; + } + + r = bind(m->mdns_ipv6_fd, &sa.sa, sizeof(sa.in6)); + if (r < 0) { + r = log_error_errno(errno, "mDNS-IPv6: Failed to bind socket: %m"); + goto fail; + } + } else { + /* enable SO_REUSEADDR for the case that the user really wants multiple mDNS responders */ + r = setsockopt(m->mdns_ipv6_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)); + if (r < 0) { + r = log_error_errno(errno, "mDNS-IPv6: Failed to set SO_REUSEADDR: %m"); + goto fail; + } } r = sd_event_add_io(m->event, &m->mdns_ipv6_event_source, m->mdns_ipv6_fd, EPOLLIN, on_mdns_packet, m); From 77525fdc8d60bff55b60b9e443401187204ddfe7 Mon Sep 17 00:00:00 2001 From: Yu Watanabe Date: Thu, 16 Mar 2017 14:30:16 +0900 Subject: [PATCH 3/4] resolved: add global config option to control mDNS stack --- man/resolved.conf.xml | 15 +++++++++++++++ src/resolve/resolved-gperf.gperf | 1 + src/resolve/resolved.conf.in | 1 + 3 files changed, 17 insertions(+) diff --git a/man/resolved.conf.xml b/man/resolved.conf.xml index 4fc1ef1b33..7babc5c5c4 100644 --- a/man/resolved.conf.xml +++ b/man/resolved.conf.xml @@ -126,6 +126,21 @@ global setting is on. + + MulticastDNS= + Takes a boolean argument or + resolve. Controls Multicast DNS support (RFC 6762) on + the local host. If true, enables full Multicast DNS responder and + resolver support. If false, disables both. If set to + resolve, only resolution support is enabled, + but responding is disabled. Note that + systemd-networkd.service8 + also maintains per-link Multicast DNS settings. Multicast DNS will be + enabled on a link only if the per-link and the + global setting is on. + + DNSSEC= Takes a boolean argument or diff --git a/src/resolve/resolved-gperf.gperf b/src/resolve/resolved-gperf.gperf index 446f85cdf4..5153563b99 100644 --- a/src/resolve/resolved-gperf.gperf +++ b/src/resolve/resolved-gperf.gperf @@ -18,6 +18,7 @@ Resolve.DNS, config_parse_dns_servers, DNS_SERVER_SYSTEM, Resolve.FallbackDNS, config_parse_dns_servers, DNS_SERVER_FALLBACK, 0 Resolve.Domains, config_parse_search_domains, 0, 0 Resolve.LLMNR, config_parse_resolve_support, 0, offsetof(Manager, llmnr_support) +Resolve.MulticastDNS, config_parse_resolve_support, 0, offsetof(Manager, mdns_support) Resolve.DNSSEC, config_parse_dnssec_mode, 0, offsetof(Manager, dnssec_mode) Resolve.Cache, config_parse_bool, 0, offsetof(Manager, enable_cache) Resolve.DNSStubListener, config_parse_dns_stub_listener_mode, 0, offsetof(Manager, dns_stub_listener_mode) diff --git a/src/resolve/resolved.conf.in b/src/resolve/resolved.conf.in index 60afa151e3..e6b20620e2 100644 --- a/src/resolve/resolved.conf.in +++ b/src/resolve/resolved.conf.in @@ -16,6 +16,7 @@ #FallbackDNS=@DNS_SERVERS@ #Domains= #LLMNR=yes +#MulticastDNS=yes #DNSSEC=@DEFAULT_DNSSEC_MODE@ #Cache=yes #DNSStubListener=udp From 007ef0a224e01d9c6e3499da2bba14a2988a8a9d Mon Sep 17 00:00:00 2001 From: Yu Watanabe Date: Tue, 21 Mar 2017 13:30:48 +0900 Subject: [PATCH 4/4] resolved: detect and warn other running LLMNR stack Previously, `SO_REUSEADDR` is set before `bind`-ing socket, Thus, even if another LLMNR stack is running, `bind` always success and we cannot detect the other stack. By this commit, we first try to `bind` without `SO_REUSEADDR`, and if it fails, show warning and retry with `SO_REUSEADDR`. --- src/resolve/resolved-llmnr.c | 194 ++++++++++++++++++++++++----------- 1 file changed, 135 insertions(+), 59 deletions(-) diff --git a/src/resolve/resolved-llmnr.c b/src/resolve/resolved-llmnr.c index 3516af58ee..29396e9973 100644 --- a/src/resolve/resolved-llmnr.c +++ b/src/resolve/resolved-llmnr.c @@ -77,7 +77,7 @@ int manager_llmnr_start(Manager *m) { return 0; eaddrinuse: - log_warning("There appears to be another LLMNR responder running. Turning off LLMNR support."); + 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); @@ -136,56 +136,75 @@ int manager_llmnr_ipv4_udp_fd(Manager *m) { m->llmnr_ipv4_udp_fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); if (m->llmnr_ipv4_udp_fd < 0) - return -errno; + 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 = -errno; + 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 = -errno; + 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 = -errno; - goto fail; - } - - r = setsockopt(m->llmnr_ipv4_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)); - if (r < 0) { - r = -errno; + 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 = -errno; + 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 = -errno; + 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 = -errno; + 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) { - r = -errno; - goto fail; + 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); @@ -216,55 +235,74 @@ int manager_llmnr_ipv6_udp_fd(Manager *m) { m->llmnr_ipv6_udp_fd = socket(AF_INET6, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); if (m->llmnr_ipv6_udp_fd < 0) - return -errno; + 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 = -errno; + 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 = -errno; + 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 = -errno; + 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 = -errno; - goto fail; - } - - r = setsockopt(m->llmnr_ipv6_udp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)); - if (r < 0) { - r = -errno; + 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 = -errno; + 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 = -errno; + 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) { - r = -errno; - goto fail; + 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); @@ -338,49 +376,68 @@ int manager_llmnr_ipv4_tcp_fd(Manager *m) { m->llmnr_ipv4_tcp_fd = socket(AF_INET, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); if (m->llmnr_ipv4_tcp_fd < 0) - return -errno; + 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 = -errno; - goto fail; - } - - r = setsockopt(m->llmnr_ipv4_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)); - if (r < 0) { - r = -errno; + 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 = -errno; + 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 = -errno; + 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 = -errno; + 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) { - r = -errno; - goto fail; + 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 = -errno; + r = log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to listen the stream: %m"); goto fail; } @@ -412,48 +469,67 @@ int manager_llmnr_ipv6_tcp_fd(Manager *m) { m->llmnr_ipv6_tcp_fd = socket(AF_INET6, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); if (m->llmnr_ipv6_tcp_fd < 0) - return -errno; + 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 = -errno; + 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 = -errno; - goto fail; - } - - r = setsockopt(m->llmnr_ipv6_tcp_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)); - if (r < 0) { - r = -errno; + 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 = -errno; + 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 = -errno; + 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) { - r = -errno; - goto fail; + 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 = -errno; + r = log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to listen the stream: %m"); goto fail; }