| /* SPDX-License-Identifier: LGPL-2.1-or-later */ |
| |
| #include <netinet/in.h> |
| #include <netinet/tcp.h> |
| #include <resolv.h> |
| |
| #include "errno-util.h" |
| #include "fd-util.h" |
| #include "resolved-llmnr.h" |
| #include "resolved-manager.h" |
| |
| void manager_llmnr_stop(Manager *m) { |
| assert(m); |
| |
| m->llmnr_ipv4_udp_event_source = sd_event_source_disable_unref(m->llmnr_ipv4_udp_event_source); |
| m->llmnr_ipv4_udp_fd = safe_close(m->llmnr_ipv4_udp_fd); |
| |
| m->llmnr_ipv6_udp_event_source = sd_event_source_disable_unref(m->llmnr_ipv6_udp_event_source); |
| m->llmnr_ipv6_udp_fd = safe_close(m->llmnr_ipv6_udp_fd); |
| |
| m->llmnr_ipv4_tcp_event_source = sd_event_source_disable_unref(m->llmnr_ipv4_tcp_event_source); |
| m->llmnr_ipv4_tcp_fd = safe_close(m->llmnr_ipv4_tcp_fd); |
| |
| m->llmnr_ipv6_tcp_event_source = sd_event_source_disable_unref(m->llmnr_ipv6_tcp_event_source); |
| m->llmnr_ipv6_tcp_fd = safe_close(m->llmnr_ipv6_tcp_fd); |
| } |
| |
| int manager_llmnr_start(Manager *m) { |
| int r; |
| |
| assert(m); |
| |
| if (m->llmnr_support == RESOLVE_SUPPORT_NO) |
| return 0; |
| |
| r = manager_llmnr_ipv4_udp_fd(m); |
| if (r == -EADDRINUSE) |
| goto eaddrinuse; |
| if (r < 0) |
| return r; |
| |
| r = manager_llmnr_ipv4_tcp_fd(m); |
| if (r == -EADDRINUSE) |
| goto eaddrinuse; |
| if (r < 0) |
| return r; |
| |
| if (socket_ipv6_is_supported()) { |
| r = manager_llmnr_ipv6_udp_fd(m); |
| if (r == -EADDRINUSE) |
| goto eaddrinuse; |
| if (r < 0) |
| return r; |
| |
| r = manager_llmnr_ipv6_tcp_fd(m); |
| if (r == -EADDRINUSE) |
| goto eaddrinuse; |
| if (r < 0) |
| return r; |
| } |
| |
| return 0; |
| |
| eaddrinuse: |
| log_warning("Another LLMNR responder prohibits binding the socket to the same port. Turning off LLMNR support."); |
| m->llmnr_support = RESOLVE_SUPPORT_NO; |
| manager_llmnr_stop(m); |
| |
| return 0; |
| } |
| |
| static int on_llmnr_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) { |
| _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; |
| DnsTransaction *t = NULL; |
| Manager *m = userdata; |
| DnsScope *scope; |
| int r; |
| |
| assert(s); |
| assert(fd >= 0); |
| assert(m); |
| |
| r = manager_recv(m, fd, DNS_PROTOCOL_LLMNR, &p); |
| if (r <= 0) |
| return r; |
| |
| if (manager_packet_from_local_address(m, p)) |
| return 0; |
| |
| scope = manager_find_scope(m, p); |
| if (!scope) { |
| log_debug("Got LLMNR UDP packet on unknown scope. Ignoring."); |
| return 0; |
| } |
| |
| if (dns_packet_validate_reply(p) > 0) { |
| log_debug("Got LLMNR UDP reply packet for id %u", DNS_PACKET_ID(p)); |
| |
| dns_scope_check_conflicts(scope, p); |
| |
| t = hashmap_get(m->dns_transactions, UINT_TO_PTR(DNS_PACKET_ID(p))); |
| if (t) |
| dns_transaction_process_reply(t, p, false); |
| |
| } else if (dns_packet_validate_query(p) > 0) { |
| log_debug("Got LLMNR UDP query packet for id %u", DNS_PACKET_ID(p)); |
| |
| dns_scope_process_query(scope, NULL, p); |
| } else |
| log_debug("Invalid LLMNR UDP packet, ignoring."); |
| |
| return 0; |
| } |
| |
| static int set_llmnr_common_socket_options(int fd, int family) { |
| int r; |
| |
| r = socket_set_recvpktinfo(fd, family, true); |
| if (r < 0) |
| return r; |
| |
| r = socket_set_recvttl(fd, family, true); |
| if (r < 0) |
| return r; |
| |
| return 0; |
| } |
| |
| static int set_llmnr_common_udp_socket_options(int fd, int family) { |
| int r; |
| |
| /* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */ |
| r = socket_set_ttl(fd, family, 255); |
| if (r < 0) |
| return r; |
| |
| return 0; |
| } |
| |
| int manager_llmnr_ipv4_udp_fd(Manager *m) { |
| union sockaddr_union sa = { |
| .in.sin_family = AF_INET, |
| .in.sin_port = htobe16(LLMNR_PORT), |
| }; |
| _cleanup_close_ int s = -1; |
| int r; |
| |
| assert(m); |
| |
| if (m->llmnr_ipv4_udp_fd >= 0) |
| return m->llmnr_ipv4_udp_fd; |
| |
| s = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); |
| if (s < 0) |
| return log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to create socket: %m"); |
| |
| r = set_llmnr_common_socket_options(s, AF_INET); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set common socket options: %m"); |
| |
| r = set_llmnr_common_udp_socket_options(s, AF_INET); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set common UDP socket options: %m"); |
| |
| r = setsockopt_int(s, IPPROTO_IP, IP_MULTICAST_TTL, 255); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_TTL: %m"); |
| |
| r = setsockopt_int(s, IPPROTO_IP, IP_MULTICAST_LOOP, true); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set IP_MULTICAST_LOOP: %m"); |
| |
| /* Disable Don't-Fragment bit in the IP header */ |
| r = setsockopt_int(s, IPPROTO_IP, IP_MTU_DISCOVER, IP_PMTUDISC_DONT); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set IP_MTU_DISCOVER: %m"); |
| |
| /* first try to bind without SO_REUSEADDR to detect another LLMNR responder */ |
| r = bind(s, &sa.sa, sizeof(sa.in)); |
| if (r < 0) { |
| if (errno != EADDRINUSE) |
| return log_error_errno(errno, "LLMNR-IPv4(UDP): Failed to bind socket: %m"); |
| |
| 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_int(s, SOL_SOCKET, SO_REUSEADDR, true); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to set SO_REUSEADDR: %m"); |
| |
| r = bind(s, &sa.sa, sizeof(sa.in)); |
| if (r < 0) |
| return log_error_errno(errno, "LLMNR-IPv4(UDP): 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-IPv4(UDP): Failed to set SO_REUSEADDR: %m"); |
| } |
| |
| r = sd_event_add_io(m->event, &m->llmnr_ipv4_udp_event_source, s, EPOLLIN, on_llmnr_packet, m); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv4(UDP): Failed to create event source: %m"); |
| |
| (void) sd_event_source_set_description(m->llmnr_ipv4_udp_event_source, "llmnr-ipv4-udp"); |
| |
| return m->llmnr_ipv4_udp_fd = TAKE_FD(s); |
| } |
| |
| int manager_llmnr_ipv6_udp_fd(Manager *m) { |
| union sockaddr_union sa = { |
| .in6.sin6_family = AF_INET6, |
| .in6.sin6_port = htobe16(LLMNR_PORT), |
| }; |
| _cleanup_close_ int s = -1; |
| int r; |
| |
| assert(m); |
| |
| if (m->llmnr_ipv6_udp_fd >= 0) |
| return m->llmnr_ipv6_udp_fd; |
| |
| s = socket(AF_INET6, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); |
| if (s < 0) |
| return log_error_errno(errno, "LLMNR-IPv6(UDP): Failed to create socket: %m"); |
| |
| r = set_llmnr_common_socket_options(s, AF_INET6); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set common socket options: %m"); |
| |
| r = set_llmnr_common_udp_socket_options(s, AF_INET6); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set common UDP socket options: %m"); |
| |
| /* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */ |
| r = setsockopt_int(s, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, 255); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set IPV6_MULTICAST_HOPS: %m"); |
| |
| r = setsockopt_int(s, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, true); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set IPV6_MULTICAST_LOOP: %m"); |
| |
| r = setsockopt_int(s, IPPROTO_IPV6, IPV6_V6ONLY, true); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set IPV6_V6ONLY: %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(UDP): Failed to bind socket: %m"); |
| |
| 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_int(s, SOL_SOCKET, SO_REUSEADDR, true); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to set SO_REUSEADDR: %m"); |
| |
| r = bind(s, &sa.sa, sizeof(sa.in6)); |
| if (r < 0) |
| return log_error_errno(errno, "LLMNR-IPv6(UDP): 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(UDP): Failed to set SO_REUSEADDR: %m"); |
| } |
| |
| r = sd_event_add_io(m->event, &m->llmnr_ipv6_udp_event_source, s, EPOLLIN, on_llmnr_packet, m); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv6(UDP): Failed to create event source: %m"); |
| |
| (void) sd_event_source_set_description(m->llmnr_ipv6_udp_event_source, "llmnr-ipv6-udp"); |
| |
| return m->llmnr_ipv6_udp_fd = TAKE_FD(s); |
| } |
| |
| static int on_llmnr_stream_packet(DnsStream *s) { |
| _cleanup_(dns_packet_unrefp) DnsPacket *p = NULL; |
| DnsScope *scope; |
| |
| assert(s); |
| |
| p = dns_stream_take_read_packet(s); |
| assert(p); |
| |
| scope = manager_find_scope(s->manager, p); |
| if (!scope) |
| log_debug("Got LLMNR TCP packet on unknown scope. Ignoring."); |
| else if (dns_packet_validate_query(p) > 0) { |
| log_debug("Got LLMNR TCP query packet for id %u", DNS_PACKET_ID(p)); |
| |
| dns_scope_process_query(scope, s, p); |
| } else |
| log_debug("Invalid LLMNR TCP packet, ignoring."); |
| |
| dns_stream_unref(s); |
| return 0; |
| } |
| |
| static int on_llmnr_stream(sd_event_source *s, int fd, uint32_t revents, void *userdata) { |
| DnsStream *stream; |
| Manager *m = userdata; |
| int cfd, r; |
| |
| cfd = accept4(fd, NULL, NULL, SOCK_NONBLOCK|SOCK_CLOEXEC); |
| if (cfd < 0) { |
| if (ERRNO_IS_ACCEPT_AGAIN(errno)) |
| return 0; |
| |
| return -errno; |
| } |
| |
| r = dns_stream_new(m, &stream, DNS_STREAM_LLMNR_RECV, DNS_PROTOCOL_LLMNR, cfd, NULL); |
| if (r < 0) { |
| safe_close(cfd); |
| return r; |
| } |
| |
| stream->on_packet = on_llmnr_stream_packet; |
| /* We don't configure a "complete" handler here, we rely on the default handler than simply drops the |
| * reference to the stream, thus freeing it */ |
| return 0; |
| } |
| |
| static int set_llmnr_common_tcp_socket_options(int fd, int family) { |
| int r; |
| |
| /* RFC 4795, section 2.5. requires setting the TTL of TCP streams to 1 */ |
| r = socket_set_ttl(fd, family, 1); |
| if (r < 0) |
| return r; |
| |
| r = setsockopt_int(fd, IPPROTO_TCP, TCP_FASTOPEN, 5); /* Everybody appears to pick qlen=5, let's do the same here. */ |
| if (r < 0) |
| log_debug_errno(r, "Failed to enable TCP_FASTOPEN on TCP listening socket, ignoring: %m"); |
| |
| r = setsockopt_int(fd, IPPROTO_TCP, TCP_NODELAY, true); |
| if (r < 0) |
| log_debug_errno(r, "Failed to enable TCP_NODELAY mode, ignoring: %m"); |
| |
| return 0; |
| } |
| |
| int manager_llmnr_ipv4_tcp_fd(Manager *m) { |
| union sockaddr_union sa = { |
| .in.sin_family = AF_INET, |
| .in.sin_port = htobe16(LLMNR_PORT), |
| }; |
| _cleanup_close_ int s = -1; |
| int r; |
| |
| assert(m); |
| |
| if (m->llmnr_ipv4_tcp_fd >= 0) |
| return m->llmnr_ipv4_tcp_fd; |
| |
| s = socket(AF_INET, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); |
| if (s < 0) |
| return log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to create socket: %m"); |
| |
| r = set_llmnr_common_socket_options(s, AF_INET); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set common socket options: %m"); |
| |
| r = set_llmnr_common_tcp_socket_options(s, AF_INET); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set common TCP socket options: %m"); |
| |
| /* Disable Don't-Fragment bit in the IP header */ |
| r = setsockopt_int(s, IPPROTO_IP, IP_MTU_DISCOVER, IP_PMTUDISC_DONT); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set IP_MTU_DISCOVER: %m"); |
| |
| /* first try to bind without SO_REUSEADDR to detect another LLMNR responder */ |
| r = bind(s, &sa.sa, sizeof(sa.in)); |
| if (r < 0) { |
| if (errno != EADDRINUSE) |
| return log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to bind socket: %m"); |
| |
| 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_int(s, SOL_SOCKET, SO_REUSEADDR, true); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to set SO_REUSEADDR: %m"); |
| |
| r = bind(s, &sa.sa, sizeof(sa.in)); |
| if (r < 0) |
| return log_error_errno(errno, "LLMNR-IPv4(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-IPv4(TCP): Failed to set SO_REUSEADDR: %m"); |
| } |
| |
| r = listen(s, SOMAXCONN); |
| if (r < 0) |
| return log_error_errno(errno, "LLMNR-IPv4(TCP): Failed to listen the stream: %m"); |
| |
| r = sd_event_add_io(m->event, &m->llmnr_ipv4_tcp_event_source, s, EPOLLIN, on_llmnr_stream, m); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv4(TCP): Failed to create event source: %m"); |
| |
| (void) sd_event_source_set_description(m->llmnr_ipv4_tcp_event_source, "llmnr-ipv4-tcp"); |
| |
| return m->llmnr_ipv4_tcp_fd = TAKE_FD(s); |
| } |
| |
| int manager_llmnr_ipv6_tcp_fd(Manager *m) { |
| union sockaddr_union sa = { |
| .in6.sin6_family = AF_INET6, |
| .in6.sin6_port = htobe16(LLMNR_PORT), |
| }; |
| _cleanup_close_ int s = -1; |
| int r; |
| |
| assert(m); |
| |
| if (m->llmnr_ipv6_tcp_fd >= 0) |
| return m->llmnr_ipv6_tcp_fd; |
| |
| s = socket(AF_INET6, SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); |
| if (s < 0) |
| return log_error_errno(errno, "LLMNR-IPv6(TCP): Failed to create socket: %m"); |
| |
| r = setsockopt_int(s, IPPROTO_IPV6, IPV6_V6ONLY, true); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set IPV6_V6ONLY: %m"); |
| |
| r = set_llmnr_common_socket_options(s, AF_INET6); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set common socket options: %m"); |
| |
| r = set_llmnr_common_tcp_socket_options(s, AF_INET6); |
| if (r < 0) |
| return log_error_errno(r, "LLMNR-IPv6(TCP): Failed to set common TCP socket options: %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); |
| } |
