451 lines
17 KiB
C
451 lines
17 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#include <netinet/in.h>
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#include <resolv.h>
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#include "errno-util.h"
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#include "fd-util.h"
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#include "resolved-llmnr.h"
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#include "resolved-manager.h"
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void manager_llmnr_stop(Manager *m) {
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assert(m);
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m->llmnr_ipv4_udp_event_source = sd_event_source_unref(m->llmnr_ipv4_udp_event_source);
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m->llmnr_ipv4_udp_fd = safe_close(m->llmnr_ipv4_udp_fd);
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m->llmnr_ipv6_udp_event_source = sd_event_source_unref(m->llmnr_ipv6_udp_event_source);
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m->llmnr_ipv6_udp_fd = safe_close(m->llmnr_ipv6_udp_fd);
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m->llmnr_ipv4_tcp_event_source = sd_event_source_unref(m->llmnr_ipv4_tcp_event_source);
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m->llmnr_ipv4_tcp_fd = safe_close(m->llmnr_ipv4_tcp_fd);
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m->llmnr_ipv6_tcp_event_source = sd_event_source_unref(m->llmnr_ipv6_tcp_event_source);
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m->llmnr_ipv6_tcp_fd = safe_close(m->llmnr_ipv6_tcp_fd);
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}
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int manager_llmnr_start(Manager *m) {
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int r;
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assert(m);
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if (m->llmnr_support == RESOLVE_SUPPORT_NO)
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return 0;
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r = manager_llmnr_ipv4_udp_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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r = manager_llmnr_ipv4_tcp_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_llmnr_ipv6_udp_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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r = manager_llmnr_ipv6_tcp_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("Another LLMNR responder prohibits binding the socket to the same port. Turning off LLMNR support.");
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m->llmnr_support = RESOLVE_SUPPORT_NO;
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manager_llmnr_stop(m);
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return 0;
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}
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static int on_llmnr_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
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_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
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DnsTransaction *t = NULL;
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Manager *m = userdata;
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DnsScope *scope;
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int r;
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assert(s);
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assert(fd >= 0);
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assert(m);
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r = manager_recv(m, fd, DNS_PROTOCOL_LLMNR, &p);
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if (r <= 0)
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return r;
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if (manager_our_packet(m, p))
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return 0;
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scope = manager_find_scope(m, p);
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if (!scope) {
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log_debug("Got LLMNR UDP packet on unknown scope. Ignoring.");
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return 0;
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}
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if (dns_packet_validate_reply(p) > 0) {
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log_debug("Got LLMNR UDP reply packet for id %u", DNS_PACKET_ID(p));
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dns_scope_check_conflicts(scope, p);
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t = hashmap_get(m->dns_transactions, UINT_TO_PTR(DNS_PACKET_ID(p)));
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if (t)
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dns_transaction_process_reply(t, p);
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} else if (dns_packet_validate_query(p) > 0) {
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log_debug("Got LLMNR UDP query packet for id %u", DNS_PACKET_ID(p));
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dns_scope_process_query(scope, NULL, p);
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} else
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log_debug("Invalid LLMNR UDP packet, ignoring.");
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return 0;
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}
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int manager_llmnr_ipv4_udp_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(LLMNR_PORT),
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};
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_cleanup_close_ int s = -1;
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int r;
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assert(m);
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if (m->llmnr_ipv4_udp_fd >= 0)
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return m->llmnr_ipv4_udp_fd;
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s = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
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if (s < 0)
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return log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to create socket: %m");
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/* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
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r = setsockopt_int(s, IPPROTO_IP, IP_TTL, 255);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set IP_TTL: %m");
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r = setsockopt_int(s, IPPROTO_IP, IP_MULTICAST_TTL, 255);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_TTL: %m");
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r = setsockopt_int(s, IPPROTO_IP, IP_MULTICAST_LOOP, true);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_LOOP: %m");
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r = setsockopt_int(s, IPPROTO_IP, IP_PKTINFO, true);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set IP_PKTINFO: %m");
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r = setsockopt_int(s, IPPROTO_IP, IP_RECVTTL, true);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set IP_RECVTTL: %m");
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/* Disable Don't-Fragment bit in the IP header */
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r = setsockopt_int(s, IPPROTO_IP, IP_MTU_DISCOVER, IP_PMTUDISC_DONT);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set IP_MTU_DISCOVER: %m");
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/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
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r = bind(s, &sa.sa, sizeof(sa.in));
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if (r < 0) {
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if (errno != EADDRINUSE)
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return log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to bind socket: %m");
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log_warning("LLMNR-IPv4(UDP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
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/* try again with SO_REUSEADDR */
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r = setsockopt_int(s, SOL_SOCKET, SO_REUSEADDR, true);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set SO_REUSEADDR: %m");
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r = bind(s, &sa.sa, sizeof(sa.in));
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if (r < 0)
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return log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to bind socket: %m");
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} else {
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/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
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r = setsockopt_int(s, SOL_SOCKET, SO_REUSEADDR, true);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set SO_REUSEADDR: %m");
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}
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r = sd_event_add_io(m->event, &m->llmnr_ipv4_udp_event_source, s, EPOLLIN, on_llmnr_packet, m);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to create event source: %m");
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(void) sd_event_source_set_description(m->llmnr_ipv4_udp_event_source, "llmnr-ipv4-udp");
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return m->llmnr_ipv4_udp_fd = TAKE_FD(s);
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}
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int manager_llmnr_ipv6_udp_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(LLMNR_PORT),
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};
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_cleanup_close_ int s = -1;
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int r;
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assert(m);
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if (m->llmnr_ipv6_udp_fd >= 0)
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return m->llmnr_ipv6_udp_fd;
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s = socket(AF_INET6, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
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if (s < 0)
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return log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to create socket: %m");
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r = setsockopt_int(s, IPPROTO_IPV6, IPV6_UNICAST_HOPS, 255);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set IPV6_UNICAST_HOPS: %m");
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/* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */
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r = setsockopt_int(s, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, 255);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set IPV6_MULTICAST_HOPS: %m");
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r = setsockopt_int(s, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, true);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set IPV6_MULTICAST_LOOP: %m");
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r = setsockopt_int(s, IPPROTO_IPV6, IPV6_V6ONLY, true);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set IPV6_V6ONLY: %m");
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r = setsockopt_int(s, IPPROTO_IPV6, IPV6_RECVPKTINFO, true);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set IPV6_RECVPKTINFO: %m");
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r = setsockopt_int(s, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, true);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set IPV6_RECVHOPLIMIT: %m");
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/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
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r = bind(s, &sa.sa, sizeof(sa.in6));
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if (r < 0) {
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if (errno != EADDRINUSE)
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return log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to bind socket: %m");
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log_warning("LLMNR-IPv6(UDP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
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/* try again with SO_REUSEADDR */
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r = setsockopt_int(s, SOL_SOCKET, SO_REUSEADDR, true);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set SO_REUSEADDR: %m");
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r = bind(s, &sa.sa, sizeof(sa.in6));
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if (r < 0)
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return log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to bind socket: %m");
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} else {
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/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
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r = setsockopt_int(s, SOL_SOCKET, SO_REUSEADDR, true);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set SO_REUSEADDR: %m");
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}
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r = sd_event_add_io(m->event, &m->llmnr_ipv6_udp_event_source, s, EPOLLIN, on_llmnr_packet, m);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to create event source: %m");
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(void) sd_event_source_set_description(m->llmnr_ipv6_udp_event_source, "llmnr-ipv6-udp");
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return m->llmnr_ipv6_udp_fd = TAKE_FD(s);
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}
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static int on_llmnr_stream_packet(DnsStream *s) {
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_cleanup_(dns_packet_unrefp) DnsPacket *p = NULL;
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DnsScope *scope;
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assert(s);
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p = dns_stream_take_read_packet(s);
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assert(p);
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scope = manager_find_scope(s->manager, p);
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if (!scope)
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log_debug("Got LLMNR TCP packet on unknown scope. Ignoring.");
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else if (dns_packet_validate_query(p) > 0) {
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log_debug("Got LLMNR TCP query packet for id %u", DNS_PACKET_ID(p));
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dns_scope_process_query(scope, s, p);
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} else
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log_debug("Invalid LLMNR TCP packet, ignoring.");
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dns_stream_unref(s);
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return 0;
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}
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static int on_llmnr_stream(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
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DnsStream *stream;
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Manager *m = userdata;
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int cfd, r;
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cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC);
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if (cfd < 0) {
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if (ERRNO_IS_ACCEPT_AGAIN(errno))
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return 0;
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return -errno;
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}
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r = dns_stream_new(m, &stream, DNS_STREAM_LLMNR_RECV, DNS_PROTOCOL_LLMNR, cfd, NULL);
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if (r < 0) {
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safe_close(cfd);
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return r;
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}
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stream->on_packet = on_llmnr_stream_packet;
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/* We don't configure a "complete" handler here, we rely on the default handler than simply drops the
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* reference to the stream, thus freeing it */
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return 0;
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}
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int manager_llmnr_ipv4_tcp_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(LLMNR_PORT),
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};
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_cleanup_close_ int s = -1;
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int r;
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assert(m);
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if (m->llmnr_ipv4_tcp_fd >= 0)
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return m->llmnr_ipv4_tcp_fd;
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s = socket(AF_INET, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
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if (s < 0)
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return log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to create socket: %m");
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/* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */
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r = setsockopt_int(s, IPPROTO_IP, IP_TTL, 1);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set IP_TTL: %m");
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r = setsockopt_int(s, IPPROTO_IP, IP_PKTINFO, true);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set IP_PKTINFO: %m");
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r = setsockopt_int(s, IPPROTO_IP, IP_RECVTTL, true);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set IP_RECVTTL: %m");
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/* Disable Don't-Fragment bit in the IP header */
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r = setsockopt_int(s, IPPROTO_IP, IP_MTU_DISCOVER, IP_PMTUDISC_DONT);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set IP_MTU_DISCOVER: %m");
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/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
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r = bind(s, &sa.sa, sizeof(sa.in));
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if (r < 0) {
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if (errno != EADDRINUSE)
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return log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to bind socket: %m");
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log_warning("LLMNR-IPv4(TCP): There appears to be another LLMNR responder running, or previously systemd-resolved crashed with some outstanding transfers.");
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/* try again with SO_REUSEADDR */
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r = setsockopt_int(s, SOL_SOCKET, SO_REUSEADDR, true);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set SO_REUSEADDR: %m");
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r = bind(s, &sa.sa, sizeof(sa.in));
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if (r < 0)
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return log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to bind socket: %m");
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} else {
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/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
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r = setsockopt_int(s, SOL_SOCKET, SO_REUSEADDR, true);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set SO_REUSEADDR: %m");
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}
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r = listen(s, SOMAXCONN);
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if (r < 0)
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return log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to listen the stream: %m");
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r = sd_event_add_io(m->event, &m->llmnr_ipv4_tcp_event_source, s, EPOLLIN, on_llmnr_stream, m);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to create event source: %m");
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(void) sd_event_source_set_description(m->llmnr_ipv4_tcp_event_source, "llmnr-ipv4-tcp");
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return m->llmnr_ipv4_tcp_fd = TAKE_FD(s);
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}
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int manager_llmnr_ipv6_tcp_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(LLMNR_PORT),
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};
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_cleanup_close_ int s = -1;
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int r;
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assert(m);
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if (m->llmnr_ipv6_tcp_fd >= 0)
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return m->llmnr_ipv6_tcp_fd;
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s = socket(AF_INET6, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0);
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if (s < 0)
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return log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to create socket: %m");
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/* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */
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r = setsockopt_int(s, IPPROTO_IPV6, IPV6_UNICAST_HOPS, 1);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set IPV6_UNICAST_HOPS: %m");
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r = setsockopt_int(s, IPPROTO_IPV6, IPV6_V6ONLY, true);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set IPV6_V6ONLY: %m");
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r = setsockopt_int(s, IPPROTO_IPV6, IPV6_RECVPKTINFO, true);
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if (r < 0)
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return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set IPV6_RECVPKTINFO: %m");
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r = setsockopt_int(s, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, true);
|
|
if (r < 0)
|
|
return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set IPV6_RECVHOPLIMIT: %m");
|
|
|
|
/* first try to bind without SO_REUSEADDR to detect another LLMNR responder */
|
|
r = bind(s, &sa.sa, sizeof(sa.in6));
|
|
if (r < 0) {
|
|
if (errno != EADDRINUSE)
|
|
return log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to bind socket: %m");
|
|
|
|
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_int(s, SOL_SOCKET, SO_REUSEADDR, true);
|
|
if (r < 0)
|
|
return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set SO_REUSEADDR: %m");
|
|
|
|
r = bind(s, &sa.sa, sizeof(sa.in6));
|
|
if (r < 0)
|
|
return log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to bind socket: %m");
|
|
} else {
|
|
/* enable SO_REUSEADDR for the case that the user really wants multiple LLMNR responders */
|
|
r = setsockopt_int(s, SOL_SOCKET, SO_REUSEADDR, true);
|
|
if (r < 0)
|
|
return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set SO_REUSEADDR: %m");
|
|
}
|
|
|
|
r = listen(s, SOMAXCONN);
|
|
if (r < 0)
|
|
return log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to listen the stream: %m");
|
|
|
|
r = sd_event_add_io(m->event, &m->llmnr_ipv6_tcp_event_source, s, EPOLLIN, on_llmnr_stream, m);
|
|
if (r < 0)
|
|
return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to create event source: %m");
|
|
|
|
(void) sd_event_source_set_description(m->llmnr_ipv6_tcp_event_source, "llmnr-ipv6-tcp");
|
|
|
|
return m->llmnr_ipv6_tcp_fd = TAKE_FD(s);
|
|
}
|