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1 | /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ |
2 | ||
3 | /*** | |
4 | This file is part of systemd. | |
5 | ||
6 | Copyright 2015 Daniel Mack | |
7 | ||
8 | systemd is free software; you can redistribute it and/or modify it | |
9 | under the terms of the GNU Lesser General Public License as published by | |
10 | the Free Software Foundation; either version 2.1 of the License, or | |
11 | (at your option) any later version. | |
12 | ||
13 | systemd is distributed in the hope that it will be useful, but | |
14 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | Lesser General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU Lesser General Public License | |
19 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
20 | ***/ | |
21 | ||
22 | #include <resolv.h> | |
23 | #include <netinet/in.h> | |
24 | #include <arpa/inet.h> | |
25 | ||
26 | #include "fd-util.h" | |
27 | #include "resolved-manager.h" | |
28 | #include "resolved-mdns.h" | |
29 | ||
30 | void manager_mdns_stop(Manager *m) { | |
31 | assert(m); | |
32 | ||
33 | m->mdns_ipv4_event_source = sd_event_source_unref(m->mdns_ipv4_event_source); | |
34 | m->mdns_ipv4_fd = safe_close(m->mdns_ipv4_fd); | |
35 | ||
36 | m->mdns_ipv6_event_source = sd_event_source_unref(m->mdns_ipv6_event_source); | |
37 | m->mdns_ipv6_fd = safe_close(m->mdns_ipv6_fd); | |
38 | } | |
39 | ||
40 | int manager_mdns_start(Manager *m) { | |
41 | int r; | |
42 | ||
43 | assert(m); | |
44 | ||
45 | if (m->mdns_support == SUPPORT_NO) | |
46 | return 0; | |
47 | ||
48 | r = manager_mdns_ipv4_fd(m); | |
49 | if (r == -EADDRINUSE) | |
50 | goto eaddrinuse; | |
51 | if (r < 0) | |
52 | return r; | |
53 | ||
54 | if (socket_ipv6_is_supported()) { | |
55 | r = manager_mdns_ipv6_fd(m); | |
56 | if (r == -EADDRINUSE) | |
57 | goto eaddrinuse; | |
58 | if (r < 0) | |
59 | return r; | |
60 | } | |
61 | ||
62 | return 0; | |
63 | ||
64 | eaddrinuse: | |
65 | log_warning("There appears to be another mDNS responder running. Turning off mDNS support."); | |
66 | m->mdns_support = SUPPORT_NO; | |
67 | manager_mdns_stop(m); | |
68 | ||
69 | return 0; | |
70 | } | |
71 | ||
72 | static int on_mdns_packet(sd_event_source *s, int fd, uint32_t revents, void *userdata) { | |
73 | /* TODO */ | |
74 | return 0; | |
75 | } | |
76 | ||
77 | int manager_mdns_ipv4_fd(Manager *m) { | |
78 | union sockaddr_union sa = { | |
79 | .in.sin_family = AF_INET, | |
80 | .in.sin_port = htobe16(MDNS_PORT), | |
81 | }; | |
82 | static const int one = 1, pmtu = IP_PMTUDISC_DONT, ttl = 255; | |
83 | int r; | |
84 | ||
85 | assert(m); | |
86 | ||
87 | if (m->mdns_ipv4_fd >= 0) | |
88 | return m->mdns_ipv4_fd; | |
89 | ||
90 | m->mdns_ipv4_fd = socket(AF_INET, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); | |
91 | if (m->mdns_ipv4_fd < 0) | |
92 | return -errno; | |
93 | ||
94 | r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_TTL, &ttl, sizeof(ttl)); | |
95 | if (r < 0) { | |
96 | r = -errno; | |
97 | goto fail; | |
98 | } | |
99 | ||
100 | r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_MULTICAST_TTL, &ttl, sizeof(ttl)); | |
101 | if (r < 0) { | |
102 | r = -errno; | |
103 | goto fail; | |
104 | } | |
105 | ||
106 | r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_MULTICAST_LOOP, &one, sizeof(one)); | |
107 | if (r < 0) { | |
108 | r = -errno; | |
109 | goto fail; | |
110 | } | |
111 | ||
112 | r = setsockopt(m->mdns_ipv4_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)); | |
113 | if (r < 0) { | |
114 | r = -errno; | |
115 | goto fail; | |
116 | } | |
117 | ||
118 | r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_PKTINFO, &one, sizeof(one)); | |
119 | if (r < 0) { | |
120 | r = -errno; | |
121 | goto fail; | |
122 | } | |
123 | ||
124 | r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_RECVTTL, &one, sizeof(one)); | |
125 | if (r < 0) { | |
126 | r = -errno; | |
127 | goto fail; | |
128 | } | |
129 | ||
130 | /* Disable Don't-Fragment bit in the IP header */ | |
131 | r = setsockopt(m->mdns_ipv4_fd, IPPROTO_IP, IP_MTU_DISCOVER, &pmtu, sizeof(pmtu)); | |
132 | if (r < 0) { | |
133 | r = -errno; | |
134 | goto fail; | |
135 | } | |
136 | ||
137 | r = bind(m->mdns_ipv4_fd, &sa.sa, sizeof(sa.in)); | |
138 | if (r < 0) { | |
139 | r = -errno; | |
140 | goto fail; | |
141 | } | |
142 | ||
143 | r = sd_event_add_io(m->event, &m->mdns_ipv4_event_source, m->mdns_ipv4_fd, EPOLLIN, on_mdns_packet, m); | |
144 | if (r < 0) | |
145 | goto fail; | |
146 | ||
147 | return m->mdns_ipv4_fd; | |
148 | ||
149 | fail: | |
150 | m->mdns_ipv4_fd = safe_close(m->mdns_ipv4_fd); | |
151 | return r; | |
152 | } | |
153 | ||
154 | int manager_mdns_ipv6_fd(Manager *m) { | |
155 | union sockaddr_union sa = { | |
156 | .in6.sin6_family = AF_INET6, | |
157 | .in6.sin6_port = htobe16(MDNS_PORT), | |
158 | }; | |
159 | static const int one = 1, ttl = 255; | |
160 | int r; | |
161 | ||
162 | assert(m); | |
163 | ||
164 | if (m->mdns_ipv6_fd >= 0) | |
165 | return m->mdns_ipv6_fd; | |
166 | ||
167 | m->mdns_ipv6_fd = socket(AF_INET6, SOCK_DGRAM|SOCK_CLOEXEC|SOCK_NONBLOCK, 0); | |
168 | if (m->mdns_ipv6_fd < 0) | |
169 | return -errno; | |
170 | ||
171 | r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_UNICAST_HOPS, &ttl, sizeof(ttl)); | |
172 | if (r < 0) { | |
173 | r = -errno; | |
174 | goto fail; | |
175 | } | |
176 | ||
177 | /* RFC 4795, section 2.5 recommends setting the TTL of UDP packets to 255. */ | |
178 | r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_MULTICAST_HOPS, &ttl, sizeof(ttl)); | |
179 | if (r < 0) { | |
180 | r = -errno; | |
181 | goto fail; | |
182 | } | |
183 | ||
184 | r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_MULTICAST_LOOP, &one, sizeof(one)); | |
185 | if (r < 0) { | |
186 | r = -errno; | |
187 | goto fail; | |
188 | } | |
189 | ||
190 | r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_V6ONLY, &one, sizeof(one)); | |
191 | if (r < 0) { | |
192 | r = -errno; | |
193 | goto fail; | |
194 | } | |
195 | ||
196 | r = setsockopt(m->mdns_ipv6_fd, SOL_SOCKET, SO_REUSEADDR, &one, sizeof(one)); | |
197 | if (r < 0) { | |
198 | r = -errno; | |
199 | goto fail; | |
200 | } | |
201 | ||
202 | r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_RECVPKTINFO, &one, sizeof(one)); | |
203 | if (r < 0) { | |
204 | r = -errno; | |
205 | goto fail; | |
206 | } | |
207 | ||
208 | r = setsockopt(m->mdns_ipv6_fd, IPPROTO_IPV6, IPV6_RECVHOPLIMIT, &one, sizeof(one)); | |
209 | if (r < 0) { | |
210 | r = -errno; | |
211 | goto fail; | |
212 | } | |
213 | ||
214 | r = bind(m->mdns_ipv6_fd, &sa.sa, sizeof(sa.in6)); | |
215 | if (r < 0) { | |
216 | r = -errno; | |
217 | goto fail; | |
218 | } | |
219 | ||
220 | r = sd_event_add_io(m->event, &m->mdns_ipv6_event_source, m->mdns_ipv6_fd, EPOLLIN, on_mdns_packet, m); | |
221 | if (r < 0) { | |
222 | r = -errno; | |
223 | goto fail; | |
224 | } | |
225 | ||
226 | return m->mdns_ipv6_fd; | |
227 | ||
228 | fail: | |
229 | m->mdns_ipv6_fd = safe_close(m->mdns_ipv6_fd); | |
230 | return r; | |
231 | } |