resolved: add infrastructure for mDNS related sockets
Just hook up mDNS listeners with an empty packet dispather function, introduce a config directive, man page updates etc.
This commit is contained in:
parent
2af917de2d
commit
bc7702b098
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@ -5164,6 +5164,8 @@ systemd_resolved_SOURCES = \
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src/resolve/resolved-link.c \
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src/resolve/resolved-llmnr.h \
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src/resolve/resolved-llmnr.c \
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src/resolve/resolved-mdns.h \
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src/resolve/resolved-mdns.c \
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src/resolve/resolved-def.h \
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src/resolve/resolved-dns-rr.h \
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src/resolve/resolved-dns-rr.c \
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@ -67,6 +67,7 @@ struct Link {
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unsigned n_search_domains;
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Support llmnr_support;
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Support mdns_support;
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DnsScope *unicast_scope;
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DnsScope *llmnr_ipv4_scope;
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@ -40,6 +40,7 @@
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#include "resolved-llmnr.h"
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#include "resolved-manager.h"
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#include "resolved-resolv-conf.h"
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#include "resolved-mdns.h"
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#include "socket-util.h"
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#include "string-table.h"
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#include "string-util.h"
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@ -472,6 +473,7 @@ int manager_new(Manager **ret) {
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m->llmnr_ipv4_udp_fd = m->llmnr_ipv6_udp_fd = -1;
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m->llmnr_ipv4_tcp_fd = m->llmnr_ipv6_tcp_fd = -1;
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m->mdns_ipv4_fd = m->mdns_ipv6_fd = -1;
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m->hostname_fd = -1;
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m->llmnr_support = SUPPORT_YES;
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@ -528,6 +530,10 @@ int manager_start(Manager *m) {
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if (r < 0)
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return r;
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r = manager_mdns_start(m);
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if (r < 0)
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return r;
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return 0;
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}
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@ -559,6 +565,7 @@ Manager *manager_free(Manager *m) {
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sd_event_source_unref(m->rtnl_event_source);
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manager_llmnr_stop(m);
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manager_mdns_stop(m);
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sd_bus_slot_unref(m->prepare_for_sleep_slot);
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sd_event_source_unref(m->bus_retry_event_source);
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@ -54,6 +54,7 @@ struct Manager {
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sd_event *event;
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Support llmnr_support;
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Support mdns_support;
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/* Network */
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Hashmap *links;
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@ -102,6 +103,13 @@ struct Manager {
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sd_event_source *llmnr_ipv4_tcp_event_source;
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sd_event_source *llmnr_ipv6_tcp_event_source;
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/* mDNS */
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int mdns_ipv4_fd;
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int mdns_ipv6_fd;
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sd_event_source *mdns_ipv4_event_source;
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sd_event_source *mdns_ipv6_event_source;
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/* dbus */
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sd_bus *bus;
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sd_event_source *bus_retry_event_source;
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231
src/resolve/resolved-mdns.c
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231
src/resolve/resolved-mdns.c
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@ -0,0 +1,231 @@
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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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/***
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This file is part of systemd.
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Copyright 2015 Daniel Mack
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <resolv.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include "fd-util.h"
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#include "resolved-manager.h"
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#include "resolved-mdns.h"
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void manager_mdns_stop(Manager *m) {
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assert(m);
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m->mdns_ipv4_event_source = sd_event_source_unref(m->mdns_ipv4_event_source);
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m->mdns_ipv4_fd = safe_close(m->mdns_ipv4_fd);
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m->mdns_ipv6_event_source = sd_event_source_unref(m->mdns_ipv6_event_source);
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m->mdns_ipv6_fd = safe_close(m->mdns_ipv6_fd);
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}
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int manager_mdns_start(Manager *m) {
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int r;
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assert(m);
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if (m->mdns_support == SUPPORT_NO)
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return 0;
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r = manager_mdns_ipv4_fd(m);
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if (r == -EADDRINUSE)
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goto eaddrinuse;
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if (r < 0)
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return r;
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if (socket_ipv6_is_supported()) {
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r = manager_mdns_ipv6_fd(m);
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if (r == -EADDRINUSE)
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goto eaddrinuse;
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if (r < 0)
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return r;
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}
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return 0;
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eaddrinuse:
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log_warning("There appears to be another mDNS responder running. Turning off mDNS support.");
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m->mdns_support = SUPPORT_NO;
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manager_mdns_stop(m);
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return 0;
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}
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static int on_mdns_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
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/* TODO */
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return 0;
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}
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int manager_mdns_ipv4_fd(Manager *m) {
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union sockaddr_union sa = {
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.in.sin_family = AF_INET,
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.in.sin_port = htobe16(MDNS_PORT),
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};
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static const int one = 1, pmtu = IP_PMTUDISC_DONT, ttl = 255;
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int r;
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assert(m);
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if (m->mdns_ipv4_fd >= 0)
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return m->mdns_ipv4_fd;
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m->mdns_ipv4_fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
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if (m->mdns_ipv4_fd < 0)
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return -errno;
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r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl));
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if (r < 0) {
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r = -errno;
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goto fail;
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}
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r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl));
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if (r < 0) {
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r = -errno;
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goto fail;
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}
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r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_MULTICAST_LOOP, &one, sizeof(one));
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if (r < 0) {
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r = -errno;
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goto fail;
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}
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r = setsockopt(m->mdns_ipv4_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
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if (r < 0) {
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r = -errno;
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goto fail;
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}
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r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one));
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if (r < 0) {
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r = -errno;
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goto fail;
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}
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r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one));
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if (r < 0) {
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r = -errno;
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goto fail;
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}
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/* Disable Don't-Fragment bit in the IP header */
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r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_MTU_DISCOVER, &pmtu, sizeof(pmtu));
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if (r < 0) {
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r = -errno;
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goto fail;
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}
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r = bind(m->mdns_ipv4_fd, &sa.sa, sizeof(sa.in));
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if (r < 0) {
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r = -errno;
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goto fail;
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}
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r = sd_event_add_io(m->event, &m->mdns_ipv4_event_source, m->mdns_ipv4_fd, EPOLLIN, on_mdns_packet, m);
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if (r < 0)
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goto fail;
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return m->mdns_ipv4_fd;
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fail:
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m->mdns_ipv4_fd = safe_close(m->mdns_ipv4_fd);
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return r;
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}
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int manager_mdns_ipv6_fd(Manager *m) {
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union sockaddr_union sa = {
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.in6.sin6_family = AF_INET6,
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.in6.sin6_port = htobe16(MDNS_PORT),
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};
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static const int one = 1, ttl = 255;
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int r;
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assert(m);
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if (m->mdns_ipv6_fd >= 0)
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return m->mdns_ipv6_fd;
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m->mdns_ipv6_fd = socket(AF_INET6, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
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if (m->mdns_ipv6_fd < 0)
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return -errno;
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r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl));
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if (r < 0) {
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r = -errno;
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goto fail;
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}
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/* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
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r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl));
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if (r < 0) {
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r = -errno;
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goto fail;
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}
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r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &one, sizeof(one));
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if (r < 0) {
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r = -errno;
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goto fail;
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}
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r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one));
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if (r < 0) {
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r = -errno;
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goto fail;
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}
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r = setsockopt(m->mdns_ipv6_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one));
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if (r < 0) {
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r = -errno;
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goto fail;
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}
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r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one));
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if (r < 0) {
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r = -errno;
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goto fail;
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}
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r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one));
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if (r < 0) {
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r = -errno;
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goto fail;
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}
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r = bind(m->mdns_ipv6_fd, &sa.sa, sizeof(sa.in6));
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if (r < 0) {
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r = -errno;
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goto fail;
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}
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r = sd_event_add_io(m->event, &m->mdns_ipv6_event_source, m->mdns_ipv6_fd, EPOLLIN, on_mdns_packet, m);
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if (r < 0) {
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r = -errno;
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goto fail;
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}
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return m->mdns_ipv6_fd;
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fail:
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m->mdns_ipv6_fd = safe_close(m->mdns_ipv6_fd);
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return r;
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}
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32
src/resolve/resolved-mdns.h
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32
src/resolve/resolved-mdns.h
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@ -0,0 +1,32 @@
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/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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#pragma once
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/***
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This file is part of systemd.
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Copyright 2015 Daniel Mack
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include "resolved-manager.h"
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#define MDNS_PORT 5353
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int manager_mdns_ipv4_fd(Manager *m);
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int manager_mdns_ipv6_fd(Manager *m);
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void manager_mdns_stop(Manager *m);
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int manager_mdns_start(Manager *m);
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