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/avahi-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
45static 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
66static 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_ADDRESS:
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_LOCAL:
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
336int 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
360fail:
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
370void 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
379void 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