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-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-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;
}
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;
}
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);
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