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 <stdlib.h>
25
26#include <avahi-common/timeval.h>
27#include <avahi-common/malloc.h>
28#include <avahi-common/error.h>
29#include <avahi-common/domain.h>
30
31#include "browse.h"
32
33#define TIMEOUT_MSEC 10000
34
35struct AvahiSAddressResolver {
36    AvahiServer *server;
37    AvahiAddress address;
38
39    AvahiSRecordBrowser *record_browser;
40
41    AvahiSAddressResolverCallback callback;
42    void* userdata;
43
44    AvahiRecord *ptr_record;
45    AvahiIfIndex interface;
46    AvahiProtocol protocol;
47    AvahiLookupResultFlags flags;
48
49    int retry_with_multicast;
50    int retry_with_llmnr;
51    int llmnr_has_record;
52    AvahiKey *key;
53
54    AvahiTimeEvent *time_event;
55
56    AVAHI_LLIST_FIELDS(AvahiSAddressResolver, resolver);
57};
58
59static void finish(AvahiSAddressResolver *r, AvahiResolverEvent event) {
60    assert(r);
61
62    if (r->time_event) {
63        avahi_time_event_free(r->time_event);
64        r->time_event = NULL;
65    }
66
67    switch (event) {
68        case AVAHI_RESOLVER_FAILURE:
69            r->callback(r, r->interface, r->protocol, event, &r->address, NULL, r->flags, r->userdata);
70            break;
71
72        case AVAHI_RESOLVER_FOUND:
73            assert(r->ptr_record);
74            r->callback(r, r->interface, r->protocol, event, &r->address, r->ptr_record->data.ptr.name, r->flags, r->userdata);
75            break;
76    }
77}
78
79static void time_event_callback(AvahiTimeEvent *e, void *userdata) {
80    AvahiSAddressResolver *r = userdata;
81
82    assert(e);
83    assert(r);
84
85    avahi_server_set_errno(r->server, AVAHI_ERR_TIMEOUT);
86    finish(r, AVAHI_RESOLVER_FAILURE);
87}
88
89static void start_timeout(AvahiSAddressResolver *r) {
90    struct timeval tv;
91    assert(r);
92
93    if (r->time_event)
94        return;
95
96    avahi_elapse_time(&tv, TIMEOUT_MSEC, 0);
97    r->time_event = avahi_time_event_new(r->server->time_event_queue, &tv, time_event_callback, r);
98}
99
100static void record_browser_callback(
101    AvahiSRecordBrowser*rr,
102    AvahiIfIndex interface,
103    AvahiProtocol protocol,
104    AvahiBrowserEvent event,
105    AvahiRecord *record,
106    AvahiLookupResultFlags flags,
107    void* userdata) {
108
109    AvahiSAddressResolver *r = userdata;
110
111    assert(rr);
112    assert(r);
113
114    switch (event) {
115        case AVAHI_BROWSER_NEW:
116            assert(record);
117            assert(record->key->type == AVAHI_DNS_TYPE_PTR);
118
119            if (flags & AVAHI_LOOKUP_RESULT_LLMNR)
120                r->llmnr_has_record = 1;
121
122            if (r->interface > 0 && interface != r->interface)
123                return;
124
125            if (r->protocol != AVAHI_PROTO_UNSPEC && protocol != r->protocol)
126                return;
127
128            if (r->interface <= 0)
129                r->interface = interface;
130
131            if (r->protocol == AVAHI_PROTO_UNSPEC)
132                r->protocol = protocol;
133
134            if (!r->ptr_record) {
135                r->ptr_record = avahi_record_ref(record);
136                r->flags = flags;
137
138                finish(r, AVAHI_RESOLVER_FOUND);
139            }
140            break;
141
142        case AVAHI_BROWSER_REMOVE:
143            assert(record);
144            assert(record->key->type == AVAHI_DNS_TYPE_PTR);
145
146            if (r->ptr_record && avahi_record_equal_no_ttl(record, r->ptr_record)) {
147                avahi_record_unref(r->ptr_record);
148                r->ptr_record = NULL;
149                r->flags = flags;
150
151                /** Look for a replacement */
152                avahi_s_record_browser_restart(r->record_browser);
153                start_timeout(r);
154            }
155            break;
156
157        case AVAHI_BROWSER_CACHE_EXHAUSTED:
158            break;
159
160        case AVAHI_BROWSER_ALL_FOR_NOW:
161            /* when called by _LLMNR we trigger lookup by _MULTICAST*/
162            if ((flags & AVAHI_LOOKUP_RESULT_LLMNR) && (r->retry_with_multicast) && !r->llmnr_has_record) {
163                r->retry_with_multicast = 0;
164                avahi_s_record_browser_free(r->record_browser);
165                r->record_browser = avahi_s_record_browser_new(r->server, r->interface, r->protocol, r->key, AVAHI_LOOKUP_USE_MULTICAST, record_browser_callback, r);
166
167                 if (r->record_browser) {
168                    start_timeout(r);
169                    break;
170                 }
171            }
172            break;
173
174        case AVAHI_BROWSER_FAILURE:
175            if (r->retry_with_llmnr) {
176                r->retry_with_llmnr = 0;
177                avahi_s_record_browser_free(r->record_browser);
178                r->record_browser = avahi_s_record_browser_new(r->server, r->interface, r->protocol, r->key, AVAHI_LOOKUP_USE_LLMNR, record_browser_callback, r);
179
180                if (r->record_browser) {
181                    start_timeout(r);
182                    break;
183                }
184            }
185            break;
186    }
187}
188
189AvahiSAddressResolver *avahi_s_address_resolver_new(
190    AvahiServer *server,
191    AvahiIfIndex interface,
192    AvahiProtocol protocol,
193    const AvahiAddress *address,
194    AvahiLookupFlags flags,
195    AvahiSAddressResolverCallback callback,
196    void* userdata) {
197
198    AvahiSAddressResolver *r;
199    AvahiKey *k;
200    char n[AVAHI_DOMAIN_NAME_MAX];
201
202    assert(server);
203    assert(address);
204    assert(callback);
205
206    AVAHI_CHECK_VALIDITY_RETURN_NULL(server, AVAHI_IF_VALID(interface), AVAHI_ERR_INVALID_INTERFACE);
207    AVAHI_CHECK_VALIDITY_RETURN_NULL(server, AVAHI_PROTO_VALID(protocol), AVAHI_ERR_INVALID_PROTOCOL);
208    AVAHI_CHECK_VALIDITY_RETURN_NULL(server, address->proto == AVAHI_PROTO_INET || address->proto == AVAHI_PROTO_INET6, AVAHI_ERR_INVALID_PROTOCOL);
209    AVAHI_CHECK_VALIDITY_RETURN_NULL(server, AVAHI_FLAGS_VALID(flags, AVAHI_LOOKUP_USE_WIDE_AREA|AVAHI_LOOKUP_USE_MULTICAST|AVAHI_LOOKUP_USE_LLMNR), AVAHI_ERR_INVALID_FLAGS);
210
211    avahi_reverse_lookup_name(address, n, sizeof(n));
212    if (!(k = avahi_key_new(n, AVAHI_DNS_CLASS_IN, AVAHI_DNS_TYPE_PTR))) {
213        avahi_server_set_errno(server, AVAHI_ERR_NO_MEMORY);
214        return NULL;
215    }
216
217    if (!(r = avahi_new(AvahiSAddressResolver, 1))) {
218        avahi_server_set_errno(server, AVAHI_ERR_NO_MEMORY);
219        avahi_key_unref(k);
220        return NULL;
221    }
222
223    r->server = server;
224    r->address = *address;
225    r->callback = callback;
226    r->userdata = userdata;
227    r->ptr_record = NULL;
228    r->interface = interface;
229    r->protocol = protocol;
230    r->flags = 0;
231    r->retry_with_multicast = 0;
232    r->retry_with_llmnr = 0;
233    r->llmnr_has_record = 0;
234    r->key = k;
235
236    r->record_browser = NULL;
237    AVAHI_LLIST_PREPEND(AvahiSAddressResolver, resolver, server->address_resolvers, r);
238
239    r->time_event = NULL;
240
241    if (!(flags & (AVAHI_LOOKUP_USE_MULTICAST|AVAHI_LOOKUP_USE_WIDE_AREA|AVAHI_LOOKUP_USE_LLMNR))) {
242
243        if (!server->wide_area.wide_area_lookup_engine || !avahi_wide_area_has_servers(server->wide_area.wide_area_lookup_engine))
244            flags |= AVAHI_LOOKUP_USE_LLMNR;
245        else {
246            flags |= AVAHI_LOOKUP_USE_WIDE_AREA;
247            r->retry_with_llmnr = 1;
248        }
249        r->retry_with_multicast = 1;
250    }
251
252    r->record_browser = avahi_s_record_browser_new(server, interface, protocol, k, flags, record_browser_callback, r);
253
254    if (!r->record_browser) {
255        avahi_s_address_resolver_free(r);
256        return NULL;
257    }
258
259    start_timeout(r);
260
261    return r;
262}
263
264void avahi_s_address_resolver_free(AvahiSAddressResolver *r) {
265    assert(r);
266
267    AVAHI_LLIST_REMOVE(AvahiSAddressResolver, resolver, r->server->address_resolvers, r);
268
269    if (r->record_browser)
270        avahi_s_record_browser_free(r->record_browser);
271
272    if (r->time_event)
273        avahi_time_event_free(r->time_event);
274
275    if (r->ptr_record)
276        avahi_record_unref(r->ptr_record);
277
278    if (r->key)
279        avahi_key_unref(r->key);
280
281    avahi_free(r);
282}
283