From 007ef0a224e01d9c6e3499da2bba14a2988a8a9d Mon Sep 17 00:00:00 2001 From: Yu Watanabe Date: Tue, 21 Mar 2017 13:30:48 +0900 Subject: 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(-) (limited to 'src/resolve') 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; } -- cgit v1.2.3-54-g00ecf