1 /***
2 This file is part of avahi.
3
4 avahi is free software; you can redistribute it and/or modify it
5 under the terms of the GNU Lesser General Public License as
6 published by the Free Software Foundation; either version 2.1 of the
7 License, or (at your option) any later version.
8
9 avahi is distributed in the hope that it will be useful, but WITHOUT
10 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
11 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
12 Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with avahi; if not, write to the Free Software
16 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
17 USA.
18 ***/
19
20 #ifdef HAVE_CONFIG_H
21 #include <config.h>
22 #endif
23
24 #include <string.h>
25 #include <net/if.h>
26 #include <errno.h>
27 #include <string.h>
28
29 #include <avahi-common/malloc.h>
30
31 #include "log.h"
32 #include "iface.h"
33 #include "iface-linux.h"
34
35 #ifndef IFLA_RTA
36 #include <linux/if_addr.h>
37 #define IFLA_RTA(r) ((struct rtattr*)(((char*)(r)) + NLMSG_ALIGN(sizeof(struct ifinfomsg))))
38 #endif
39
40 #ifndef IFA_RTA
41 #include <linux/if_addr.h>
42 #define IFA_RTA(r) ((struct rtattr*)(((char*)(r)) + NLMSG_ALIGN(sizeof(struct ifaddrmsg))))
43 #endif
44
netlink_list_items(AvahiNetlink * nl,uint16_t type,unsigned * ret_seq)45 static int netlink_list_items(AvahiNetlink *nl, uint16_t type, unsigned *ret_seq) {
46 struct nlmsghdr *n;
47 struct rtgenmsg *gen;
48 uint8_t req[1024];
49
50 /* Issue a wild dump NETLINK request */
51
52 memset(&req, 0, sizeof(req));
53 n = (struct nlmsghdr*) req;
54 n->nlmsg_len = NLMSG_LENGTH(sizeof(struct rtgenmsg));
55 n->nlmsg_type = type;
56 n->nlmsg_flags = NLM_F_REQUEST|NLM_F_DUMP;
57 n->nlmsg_pid = 0;
58
59 gen = NLMSG_DATA(n);
60 memset(gen, 0, sizeof(struct rtgenmsg));
61 gen->rtgen_family = AF_UNSPEC;
62
63 return avahi_netlink_send(nl, n, ret_seq);
64 }
65
netlink_callback(AvahiNetlink * nl,struct nlmsghdr * n,void * userdata)66 static void netlink_callback(AvahiNetlink *nl, struct nlmsghdr *n, void* userdata) {
67 AvahiInterfaceMonitor *m = userdata;
68
69 /* This routine is called for every RTNETLINK response packet */
70
71 assert(m);
72 assert(n);
73 assert(m->osdep.netlink == nl);
74
75 if (n->nlmsg_type == RTM_NEWLINK) {
76
77 /* A new interface appeared or an existing one has been modified */
78
79 struct ifinfomsg *ifinfomsg = NLMSG_DATA(n);
80 AvahiHwInterface *hw;
81 struct rtattr *a = NULL;
82 size_t l;
83
84 /* A (superfluous?) sanity check */
85 if (ifinfomsg->ifi_family != AF_UNSPEC)
86 return;
87
88 /* Check whether there already is an AvahiHwInterface object
89 * for this link, so that we can update its data. Note that
90 * Netlink sends us an RTM_NEWLINK not only when a new
91 * interface appears, but when it changes, too */
92
93 if (!(hw = avahi_interface_monitor_get_hw_interface(m, ifinfomsg->ifi_index)))
94
95 /* No object found, so let's create a new
96 * one. avahi_hw_interface_new() will call
97 * avahi_interface_new() internally twice for IPv4 and
98 * IPv6, so there is no need for us to do that
99 * ourselves */
100 if (!(hw = avahi_hw_interface_new(m, (AvahiIfIndex) ifinfomsg->ifi_index)))
101 return; /* OOM */
102
103 /* Check whether the flags of this interface are OK for us */
104 hw->flags_ok =
105 (ifinfomsg->ifi_flags & IFF_UP) &&
106 (!m->server->config.use_iff_running || (ifinfomsg->ifi_flags & IFF_RUNNING)) &&
107 ((ifinfomsg->ifi_flags & IFF_LOOPBACK) ||
108 (ifinfomsg->ifi_flags & IFF_MULTICAST)) &&
109 (m->server->config.allow_point_to_point || !(ifinfomsg->ifi_flags & IFF_POINTOPOINT));
110
111 /* Handle interface attributes */
112 l = NLMSG_PAYLOAD(n, sizeof(struct ifinfomsg));
113 a = IFLA_RTA(ifinfomsg);
114
115 while (RTA_OK(a, l)) {
116 switch(a->rta_type) {
117 case IFLA_IFNAME:
118
119 /* Fill in interface name */
120 avahi_free(hw->name);
121 hw->name = avahi_strndup(RTA_DATA(a), RTA_PAYLOAD(a));
122 break;
123
124 case IFLA_MTU:
125
126 /* Fill in MTU */
127 assert(RTA_PAYLOAD(a) == sizeof(unsigned int));
128 hw->mtu = *((unsigned int*) RTA_DATA(a));
129 break;
130
131 case IFLA_ADDRESS:
132
133 /* Fill in hardware (MAC) address */
134 hw->mac_address_size = RTA_PAYLOAD(a);
135 if (hw->mac_address_size > AVAHI_MAC_ADDRESS_MAX)
136 hw->mac_address_size = AVAHI_MAC_ADDRESS_MAX;
137
138 memcpy(hw->mac_address, RTA_DATA(a), hw->mac_address_size);
139 break;
140
141 default:
142 ;
143 }
144
145 a = RTA_NEXT(a, l);
146 }
147
148 /* Check whether this interface is now "relevant" for us. If
149 * it is Avahi will start to announce its records on this
150 * interface and send out queries for subscribed records on
151 * it */
152 avahi_hw_interface_check_relevant(hw);
153
154 /* Update any associated RRs of this interface. (i.e. the
155 * _workstation._tcp record containing the MAC address) */
156 avahi_hw_interface_update_rrs(hw, 0);
157
158 } else if (n->nlmsg_type == RTM_DELLINK) {
159
160 /* An interface has been removed */
161
162 struct ifinfomsg *ifinfomsg = NLMSG_DATA(n);
163 AvahiHwInterface *hw;
164
165 /* A (superfluous?) sanity check */
166 if (ifinfomsg->ifi_family != AF_UNSPEC)
167 return;
168
169 /* Get a reference to our AvahiHwInterface object of this interface */
170 if (!(hw = avahi_interface_monitor_get_hw_interface(m, (AvahiIfIndex) ifinfomsg->ifi_index)))
171 return;
172
173 /* Free our object */
174 avahi_hw_interface_free(hw, 0);
175
176 } else if (n->nlmsg_type == RTM_NEWADDR || n->nlmsg_type == RTM_DELADDR) {
177
178 /* An address has been added, modified or removed */
179
180 struct ifaddrmsg *ifaddrmsg = NLMSG_DATA(n);
181 AvahiInterface *i;
182 struct rtattr *a = NULL;
183 size_t l;
184 AvahiAddress raddr, rlocal, *r;
185 int raddr_valid = 0, rlocal_valid = 0;
186
187 /* We are only interested in IPv4 and IPv6 */
188 if (ifaddrmsg->ifa_family != AF_INET && ifaddrmsg->ifa_family != AF_INET6)
189 return;
190
191 /* Try to get a reference to our AvahiInterface object for the
192 * interface this address is assigned to. If ther is no object
193 * for this interface, we ignore this address. */
194 if (!(i = avahi_interface_monitor_get_interface(m, (AvahiIfIndex) ifaddrmsg->ifa_index, avahi_af_to_proto(ifaddrmsg->ifa_family))))
195 return;
196
197 /* Fill in address family for our new address */
198 rlocal.proto = raddr.proto = avahi_af_to_proto(ifaddrmsg->ifa_family);
199
200 l = NLMSG_PAYLOAD(n, sizeof(struct ifaddrmsg));
201 a = IFA_RTA(ifaddrmsg);
202
203 while (RTA_OK(a, l)) {
204
205 switch(a->rta_type) {
206
207 case IFA_LOCAL:
208
209 if ((rlocal.proto == AVAHI_PROTO_INET6 && RTA_PAYLOAD(a) != 16) ||
210 (rlocal.proto == AVAHI_PROTO_INET && RTA_PAYLOAD(a) != 4))
211 return;
212
213 memcpy(rlocal.data.data, RTA_DATA(a), RTA_PAYLOAD(a));
214 rlocal_valid = 1;
215
216 break;
217
218 case IFA_ADDRESS:
219
220 /* Fill in local address data. Usually this is
221 * preferable over IFA_ADDRESS if both are set,
222 * since this refers to the local address of a PPP
223 * link while IFA_ADDRESS refers to the other
224 * end. */
225
226 if ((raddr.proto == AVAHI_PROTO_INET6 && RTA_PAYLOAD(a) != 16) ||
227 (raddr.proto == AVAHI_PROTO_INET && RTA_PAYLOAD(a) != 4))
228 return;
229
230 memcpy(raddr.data.data, RTA_DATA(a), RTA_PAYLOAD(a));
231 raddr_valid = 1;
232
233 break;
234
235 default:
236 ;
237 }
238
239 a = RTA_NEXT(a, l);
240 }
241
242 /* If there was no adress attached to this message, let's quit. */
243 if (rlocal_valid)
244 r = &rlocal;
245 else if (raddr_valid)
246 r = &raddr;
247 else
248 return;
249
250 if (n->nlmsg_type == RTM_NEWADDR) {
251 AvahiInterfaceAddress *addr;
252
253 /* This address is new or has been modified, so let's get an object for it */
254 if (!(addr = avahi_interface_monitor_get_address(m, i, r)))
255
256 /* Mmm, no object existing yet, so let's create a new one */
257 if (!(addr = avahi_interface_address_new(m, i, r, ifaddrmsg->ifa_prefixlen)))
258 return; /* OOM */
259
260 /* Update the scope field for the address */
261 addr->global_scope = ifaddrmsg->ifa_scope == RT_SCOPE_UNIVERSE || ifaddrmsg->ifa_scope == RT_SCOPE_SITE;
262 addr->deprecated = !!(ifaddrmsg->ifa_flags & IFA_F_DEPRECATED);
263 } else {
264 AvahiInterfaceAddress *addr;
265 assert(n->nlmsg_type == RTM_DELADDR);
266
267 /* Try to get a reference to our AvahiInterfaceAddress object for this address */
268 if (!(addr = avahi_interface_monitor_get_address(m, i, r)))
269 return;
270
271 /* And free it */
272 avahi_interface_address_free(addr);
273 }
274
275 /* Avahi only considers interfaces with at least one address
276 * attached relevant. Since we migh have added or removed an
277 * address, let's have it check again whether the interface is
278 * now relevant */
279 avahi_interface_check_relevant(i);
280
281 /* Update any associated RRs, like A or AAAA for our new/removed address */
282 avahi_interface_update_rrs(i, 0);
283
284 } else if (n->nlmsg_type == NLMSG_DONE) {
285
286 /* This wild dump request ended, so let's see what we do next */
287
288 if (m->osdep.list == LIST_IFACE) {
289
290 /* Mmmm, interfaces have been wild dumped already, so
291 * let's go on with wild dumping the addresses */
292
293 if (netlink_list_items(m->osdep.netlink, RTM_GETADDR, &m->osdep.query_addr_seq) < 0) {
294 avahi_log_warn("NETLINK: Failed to list addrs: %s", strerror(errno));
295 m->osdep.list = LIST_DONE;
296 } else
297
298 /* Update state information */
299 m->osdep.list = LIST_ADDR;
300
301 } else
302 /* We're done. Tell avahi_interface_monitor_sync() to finish. */
303 m->osdep.list = LIST_DONE;
304
305 if (m->osdep.list == LIST_DONE) {
306
307 /* Only after this boolean variable has been set, Avahi
308 * will start to announce or browse on all interfaces. It
309 * is originaly set to 0, which means that relevancy
310 * checks and RR updates are disabled during the wild
311 * dumps. */
312 m->list_complete = 1;
313
314 /* So let's check if any interfaces are relevant now */
315 avahi_interface_monitor_check_relevant(m);
316
317 /* And update all RRs attached to any interface */
318 avahi_interface_monitor_update_rrs(m, 0);
319
320 /* Tell the user that the wild dump is complete */
321 avahi_log_info("Network interface enumeration completed.");
322 }
323
324 } else if (n->nlmsg_type == NLMSG_ERROR &&
325 (n->nlmsg_seq == m->osdep.query_link_seq || n->nlmsg_seq == m->osdep.query_addr_seq)) {
326 struct nlmsgerr *e = NLMSG_DATA (n);
327
328 /* Some kind of error happened. Let's just tell the user and
329 * ignore it otherwise */
330
331 if (e->error)
332 avahi_log_warn("NETLINK: Failed to browse: %s", strerror(-e->error));
333 }
334 }
335
avahi_interface_monitor_init_osdep(AvahiInterfaceMonitor * m)336 int avahi_interface_monitor_init_osdep(AvahiInterfaceMonitor *m) {
337 assert(m);
338
339 /* Initialize our own data */
340
341 m->osdep.netlink = NULL;
342 m->osdep.query_addr_seq = m->osdep.query_link_seq = 0;
343
344 /* Create a netlink object for us. It abstracts some things and
345 * makes netlink easier to use. It will attach to the main loop
346 * for us and call netlink_callback() whenever an event
347 * happens. */
348 if (!(m->osdep.netlink = avahi_netlink_new(m->server->poll_api, RTMGRP_LINK|RTMGRP_IPV4_IFADDR|RTMGRP_IPV6_IFADDR, netlink_callback, m)))
349 goto fail;
350
351 /* Set the initial state. */
352 m->osdep.list = LIST_IFACE;
353
354 /* Start the wild dump for the interfaces */
355 if (netlink_list_items(m->osdep.netlink, RTM_GETLINK, &m->osdep.query_link_seq) < 0)
356 goto fail;
357
358 return 0;
359
360 fail:
361
362 if (m->osdep.netlink) {
363 avahi_netlink_free(m->osdep.netlink);
364 m->osdep.netlink = NULL;
365 }
366
367 return -1;
368 }
369
avahi_interface_monitor_free_osdep(AvahiInterfaceMonitor * m)370 void avahi_interface_monitor_free_osdep(AvahiInterfaceMonitor *m) {
371 assert(m);
372
373 if (m->osdep.netlink) {
374 avahi_netlink_free(m->osdep.netlink);
375 m->osdep.netlink = NULL;
376 }
377 }
378
avahi_interface_monitor_sync(AvahiInterfaceMonitor * m)379 void avahi_interface_monitor_sync(AvahiInterfaceMonitor *m) {
380 assert(m);
381
382 /* Let's handle netlink events until we are done with wild
383 * dumping */
384
385 while (!m->list_complete)
386 if (!avahi_netlink_work(m->osdep.netlink, 1) == 0)
387 break;
388
389 /* At this point Avahi knows about all local interfaces and
390 * addresses in existance. */
391 }
392