From bc7702b098b63031767174206f5df14a8ccb45cf Mon Sep 17 00:00:00 2001 From: Daniel Mack Date: Fri, 10 Jul 2015 15:48:13 -0400 Subject: [PATCH] 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. --- Makefile.am | 2 + src/resolve/resolved-link.h | 1 + src/resolve/resolved-manager.c | 7 + src/resolve/resolved-manager.h | 8 ++ src/resolve/resolved-mdns.c | 231 +++++++++++++++++++++++++++++++++ src/resolve/resolved-mdns.h | 32 +++++ 6 files changed, 281 insertions(+) create mode 100644 src/resolve/resolved-mdns.c create mode 100644 src/resolve/resolved-mdns.h diff --git a/Makefile.am b/Makefile.am index 1dda8c5137f..41d0daaba27 100644 --- a/Makefile.am +++ b/Makefile.am @@ -5164,6 +5164,8 @@ systemd_resolved_SOURCES = \ src/resolve/resolved-link.c \ src/resolve/resolved-llmnr.h \ src/resolve/resolved-llmnr.c \ + src/resolve/resolved-mdns.h \ + src/resolve/resolved-mdns.c \ src/resolve/resolved-def.h \ src/resolve/resolved-dns-rr.h \ src/resolve/resolved-dns-rr.c \ diff --git a/src/resolve/resolved-link.h b/src/resolve/resolved-link.h index eb00015bd55..3093050c98a 100644 --- a/src/resolve/resolved-link.h +++ b/src/resolve/resolved-link.h @@ -67,6 +67,7 @@ struct Link { unsigned n_search_domains; Support llmnr_support; + Support mdns_support; DnsScope *unicast_scope; DnsScope *llmnr_ipv4_scope; diff --git a/src/resolve/resolved-manager.c b/src/resolve/resolved-manager.c index 5a3696ccb05..fc2fb4d47c7 100644 --- a/src/resolve/resolved-manager.c +++ b/src/resolve/resolved-manager.c @@ -40,6 +40,7 @@ #include "resolved-llmnr.h" #include "resolved-manager.h" #include "resolved-resolv-conf.h" +#include "resolved-mdns.h" #include "socket-util.h" #include "string-table.h" #include "string-util.h" @@ -472,6 +473,7 @@ int manager_new(Manager **ret) { m->llmnr_ipv4_udp_fd = m->llmnr_ipv6_udp_fd = -1; m->llmnr_ipv4_tcp_fd = m->llmnr_ipv6_tcp_fd = -1; + m->mdns_ipv4_fd = m->mdns_ipv6_fd = -1; m->hostname_fd = -1; m->llmnr_support = SUPPORT_YES; @@ -528,6 +530,10 @@ int manager_start(Manager *m) { if (r < 0) return r; + r = manager_mdns_start(m); + if (r < 0) + return r; + return 0; } @@ -559,6 +565,7 @@ Manager *manager_free(Manager *m) { sd_event_source_unref(m->rtnl_event_source); manager_llmnr_stop(m); + manager_mdns_stop(m); sd_bus_slot_unref(m->prepare_for_sleep_slot); sd_event_source_unref(m->bus_retry_event_source); diff --git a/src/resolve/resolved-manager.h b/src/resolve/resolved-manager.h index 1056f23ab7c..b52273403a5 100644 --- a/src/resolve/resolved-manager.h +++ b/src/resolve/resolved-manager.h @@ -54,6 +54,7 @@ struct Manager { sd_event *event; Support llmnr_support; + Support mdns_support; /* Network */ Hashmap *links; @@ -102,6 +103,13 @@ struct Manager { sd_event_source *llmnr_ipv4_tcp_event_source; sd_event_source *llmnr_ipv6_tcp_event_source; + /* mDNS */ + int mdns_ipv4_fd; + int mdns_ipv6_fd; + + sd_event_source *mdns_ipv4_event_source; + sd_event_source *mdns_ipv6_event_source; + /* dbus */ sd_bus *bus; sd_event_source *bus_retry_event_source; diff --git a/src/resolve/resolved-mdns.c b/src/resolve/resolved-mdns.c new file mode 100644 index 00000000000..6767706f6e2 --- /dev/null +++ b/src/resolve/resolved-mdns.c @@ -0,0 +1,231 @@ +/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ + +/*** + This file is part of systemd. + + Copyright 2015 Daniel Mack + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + systemd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see . + ***/ + +#include +#include +#include + +#include "fd-util.h" +#include "resolved-manager.h" +#include "resolved-mdns.h" + +void manager_mdns_stop(Manager *m) { + assert(m); + + m->mdns_ipv4_event_source = sd_event_source_unref(m->mdns_ipv4_event_source); + m->mdns_ipv4_fd = safe_close(m->mdns_ipv4_fd); + + m->mdns_ipv6_event_source = sd_event_source_unref(m->mdns_ipv6_event_source); + m->mdns_ipv6_fd = safe_close(m->mdns_ipv6_fd); +} + +int manager_mdns_start(Manager *m) { + int r; + + assert(m); + + if (m->mdns_support == SUPPORT_NO) + return 0; + + r = manager_mdns_ipv4_fd(m); + if (r == -EADDRINUSE) + goto eaddrinuse; + if (r < 0) + return r; + + if (socket_ipv6_is_supported()) { + r = manager_mdns_ipv6_fd(m); + if (r == -EADDRINUSE) + goto eaddrinuse; + if (r < 0) + return r; + } + + return 0; + +eaddrinuse: + log_warning("There appears to be another mDNS responder running. Turning off mDNS support."); + m->mdns_support = SUPPORT_NO; + manager_mdns_stop(m); + + return 0; +} + +static int on_mdns_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) { + /* TODO */ + return 0; +} + +int manager_mdns_ipv4_fd(Manager *m) { + union sockaddr_union sa = { + .in.sin_family = AF_INET, + .in.sin_port = htobe16(MDNS_PORT), + }; + static const int one = 1, pmtu = IP_PMTUDISC_DONT, ttl = 255; + int r; + + assert(m); + + if (m->mdns_ipv4_fd >= 0) + return m->mdns_ipv4_fd; + + m->mdns_ipv4_fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); + if (m->mdns_ipv4_fd < 0) + return -errno; + + r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl)); + if (r < 0) { + r = -errno; + goto fail; + } + + r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)); + if (r < 0) { + r = -errno; + 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; + goto fail; + } + + r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one)); + if (r < 0) { + r = -errno; + goto fail; + } + + r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one)); + if (r < 0) { + r = -errno; + 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; + goto fail; + } + + r = bind(m->mdns_ipv4_fd, &sa.sa, sizeof(sa.in)); + if (r < 0) { + r = -errno; + goto fail; + } + + r = sd_event_add_io(m->event, &m->mdns_ipv4_event_source, m->mdns_ipv4_fd, EPOLLIN, on_mdns_packet, m); + if (r < 0) + goto fail; + + return m->mdns_ipv4_fd; + +fail: + m->mdns_ipv4_fd = safe_close(m->mdns_ipv4_fd); + return r; +} + +int manager_mdns_ipv6_fd(Manager *m) { + union sockaddr_union sa = { + .in6.sin6_family = AF_INET6, + .in6.sin6_port = htobe16(MDNS_PORT), + }; + static const int one = 1, ttl = 255; + int r; + + assert(m); + + if (m->mdns_ipv6_fd >= 0) + return m->mdns_ipv6_fd; + + m->mdns_ipv6_fd = socket(AF_INET6, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); + if (m->mdns_ipv6_fd < 0) + return -errno; + + r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl)); + if (r < 0) { + r = -errno; + 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; + goto fail; + } + + r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &one, sizeof(one)); + if (r < 0) { + r = -errno; + 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; + goto fail; + } + + r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one)); + if (r < 0) { + r = -errno; + goto fail; + } + + r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one)); + if (r < 0) { + r = -errno; + goto fail; + } + + r = bind(m->mdns_ipv6_fd, &sa.sa, sizeof(sa.in6)); + if (r < 0) { + r = -errno; + goto fail; + } + + r = sd_event_add_io(m->event, &m->mdns_ipv6_event_source, m->mdns_ipv6_fd, EPOLLIN, on_mdns_packet, m); + if (r < 0) { + r = -errno; + goto fail; + } + + return m->mdns_ipv6_fd; + +fail: + m->mdns_ipv6_fd = safe_close(m->mdns_ipv6_fd); + return r; +} diff --git a/src/resolve/resolved-mdns.h b/src/resolve/resolved-mdns.h new file mode 100644 index 00000000000..8a840106153 --- /dev/null +++ b/src/resolve/resolved-mdns.h @@ -0,0 +1,32 @@ +/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ + +#pragma once + +/*** + This file is part of systemd. + + Copyright 2015 Daniel Mack + + systemd is free software; you can redistribute it and/or modify it + under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation; either version 2.1 of the License, or + (at your option) any later version. + + systemd is distributed in the hope that it will be useful, but + WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with systemd; If not, see . +***/ + +#include "resolved-manager.h" + +#define MDNS_PORT 5353 + +int manager_mdns_ipv4_fd(Manager *m); +int manager_mdns_ipv6_fd(Manager *m); + +void manager_mdns_stop(Manager *m); +int manager_mdns_start(Manager *m); -- 2.39.2