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      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/domain.h>
     27 #include <avahi-common/timeval.h>
     28 #include "avahi-common/avahi-malloc.h"
     29 #include <avahi-common/error.h>
     30 
     31 #include "browse.h"
     32 #include "log.h"
     33 
     34 #define TIMEOUT_MSEC 5000
     35 
     36 struct AvahiSHostNameResolver {
     37     AvahiServer *server;
     38     char *host_name;
     39 
     40     AvahiSRecordBrowser *record_browser_a;
     41     AvahiSRecordBrowser *record_browser_aaaa;
     42 
     43     AvahiSHostNameResolverCallback callback;
     44     void* userdata;
     45 
     46     AvahiRecord *address_record;
     47     AvahiIfIndex interface;
     48     AvahiProtocol protocol;
     49     AvahiLookupResultFlags flags;
     50 
     51     AvahiTimeEvent *time_event;
     52 
     53     AVAHI_LLIST_FIELDS(AvahiSHostNameResolver, resolver);
     54 };
     55 
     56 static void finish(AvahiSHostNameResolver *r, AvahiResolverEvent event) {
     57     assert(r);
     58 
     59     if (r->time_event) {
     60         avahi_time_event_free(r->time_event);
     61         r->time_event = NULL;
     62     }
     63 
     64     switch (event) {
     65         case AVAHI_RESOLVER_FOUND: {
     66             AvahiAddress a;
     67 
     68             assert(r->address_record);
     69 
     70             switch (r->address_record->key->type) {
     71                 case AVAHI_DNS_TYPE_A:
     72                     a.proto = AVAHI_PROTO_INET;
     73                     a.data.ipv4 = r->address_record->data.a.address;
     74                     break;
     75 
     76                 case AVAHI_DNS_TYPE_AAAA:
     77                     a.proto = AVAHI_PROTO_INET6;
     78                     a.data.ipv6 = r->address_record->data.aaaa.address;
     79                     break;
     80 
     81                 default:
     82                     abort();
     83             }
     84 
     85             r->callback(r, r->interface, r->protocol, AVAHI_RESOLVER_FOUND, r->address_record->key->name, &a, r->flags, r->userdata);
     86             break;
     87 
     88         }
     89 
     90         case AVAHI_RESOLVER_FAILURE:
     91 
     92             r->callback(r, r->interface, r->protocol, event, r->host_name, NULL, r->flags, r->userdata);
     93             break;
     94     }
     95 }
     96 
     97 static void time_event_callback(AvahiTimeEvent *e, void *userdata) {
     98     AvahiSHostNameResolver *r = userdata;
     99 
    100     assert(e);
    101     assert(r);
    102 
    103     avahi_server_set_errno(r->server, AVAHI_ERR_TIMEOUT);
    104     finish(r, AVAHI_RESOLVER_FAILURE);
    105 }
    106 
    107 static void start_timeout(AvahiSHostNameResolver *r) {
    108     struct timeval tv;
    109     assert(r);
    110 
    111     if (r->time_event)
    112         return;
    113 
    114     avahi_elapse_time(&tv, TIMEOUT_MSEC, 0);
    115 
    116     r->time_event = avahi_time_event_new(r->server->time_event_queue, &tv, time_event_callback, r);
    117 }
    118 
    119 static void record_browser_callback(
    120     AvahiSRecordBrowser*rr,
    121     AvahiIfIndex interface,
    122     AvahiProtocol protocol,
    123     AvahiBrowserEvent event,
    124     AvahiRecord *record,
    125     AvahiLookupResultFlags flags,
    126     void* userdata) {
    127 
    128     AvahiSHostNameResolver *r = userdata;
    129 
    130     assert(rr);
    131     assert(r);
    132 
    133 
    134     switch (event) {
    135         case AVAHI_BROWSER_NEW:
    136             assert(record);
    137             assert(record->key->type == AVAHI_DNS_TYPE_A || record->key->type == AVAHI_DNS_TYPE_AAAA);
    138 
    139             if (r->interface > 0 && interface != r->interface)
    140                 return;
    141 
    142             if (r->protocol != AVAHI_PROTO_UNSPEC && protocol != r->protocol)
    143                 return;
    144 
    145             if (r->interface <= 0)
    146                 r->interface = interface;
    147 
    148             if (r->protocol == AVAHI_PROTO_UNSPEC)
    149                 r->protocol = protocol;
    150 
    151             if (!r->address_record) {
    152                 r->address_record = avahi_record_ref(record);
    153                 r->flags = flags;
    154 
    155                 finish(r, AVAHI_RESOLVER_FOUND);
    156             }
    157 
    158             break;
    159 
    160         case AVAHI_BROWSER_REMOVE:
    161             assert(record);
    162             assert(record->key->type == AVAHI_DNS_TYPE_A || record->key->type == AVAHI_DNS_TYPE_AAAA);
    163 
    164             if (r->address_record && avahi_record_equal_no_ttl(record, r->address_record)) {
    165                 avahi_record_unref(r->address_record);
    166                 r->address_record = NULL;
    167 
    168                 r->flags = flags;
    169 
    170 
    171                 /** Look for a replacement */
    172                 if (r->record_browser_aaaa)
    173                     avahi_s_record_browser_restart(r->record_browser_aaaa);
    174                 if (r->record_browser_a)
    175                     avahi_s_record_browser_restart(r->record_browser_a);
    176 
    177                 start_timeout(r);
    178             }
    179 
    180             break;
    181 
    182         case AVAHI_BROWSER_CACHE_EXHAUSTED:
    183         case AVAHI_BROWSER_ALL_FOR_NOW:
    184             /* Ignore */
    185             break;
    186 
    187         case AVAHI_BROWSER_FAILURE:
    188 
    189             /* Stop browsers */
    190 
    191             if (r->record_browser_aaaa)
    192                 avahi_s_record_browser_free(r->record_browser_aaaa);
    193             if (r->record_browser_a)
    194                 avahi_s_record_browser_free(r->record_browser_a);
    195 
    196             r->record_browser_a = r->record_browser_aaaa = NULL;
    197             r->flags = flags;
    198 
    199             finish(r, AVAHI_RESOLVER_FAILURE);
    200             break;
    201     }
    202 }
    203 
    204 AvahiSHostNameResolver *avahi_s_host_name_resolver_new(
    205     AvahiServer *server,
    206     AvahiIfIndex interface,
    207     AvahiProtocol protocol,
    208     const char *host_name,
    209     AvahiProtocol aprotocol,
    210     AvahiLookupFlags flags,
    211     AvahiSHostNameResolverCallback callback,
    212     void* userdata) {
    213 
    214     AvahiSHostNameResolver *r;
    215     AvahiKey *k;
    216 
    217     assert(server);
    218     assert(host_name);
    219     assert(callback);
    220 
    221     AVAHI_CHECK_VALIDITY_RETURN_NULL(server, AVAHI_IF_VALID(interface), AVAHI_ERR_INVALID_INTERFACE);
    222     AVAHI_CHECK_VALIDITY_RETURN_NULL(server, AVAHI_PROTO_VALID(protocol), AVAHI_ERR_INVALID_PROTOCOL);
    223     AVAHI_CHECK_VALIDITY_RETURN_NULL(server, avahi_is_valid_fqdn(host_name), AVAHI_ERR_INVALID_HOST_NAME);
    224     AVAHI_CHECK_VALIDITY_RETURN_NULL(server, AVAHI_PROTO_VALID(aprotocol), AVAHI_ERR_INVALID_PROTOCOL);
    225     AVAHI_CHECK_VALIDITY_RETURN_NULL(server, AVAHI_FLAGS_VALID(flags, AVAHI_LOOKUP_USE_WIDE_AREA|AVAHI_LOOKUP_USE_MULTICAST), AVAHI_ERR_INVALID_FLAGS);
    226 
    227     if (!(r = avahi_new(AvahiSHostNameResolver, 1))) {
    228         avahi_server_set_errno(server, AVAHI_ERR_NO_MEMORY);
    229         return NULL;
    230     }
    231 
    232     r->server = server;
    233     r->host_name = avahi_normalize_name_strdup(host_name);
    234     r->callback = callback;
    235     r->userdata = userdata;
    236     r->address_record = NULL;
    237     r->interface = interface;
    238     r->protocol = protocol;
    239     r->flags = 0;
    240 
    241     r->record_browser_a = r->record_browser_aaaa = NULL;
    242 
    243     r->time_event = NULL;
    244 
    245     AVAHI_LLIST_PREPEND(AvahiSHostNameResolver, resolver, server->host_name_resolvers, r);
    246 
    247     r->record_browser_aaaa = r->record_browser_a = NULL;
    248 
    249     if (aprotocol == AVAHI_PROTO_INET || aprotocol == AVAHI_PROTO_UNSPEC) {
    250         k = avahi_key_new(host_name, AVAHI_DNS_CLASS_IN, AVAHI_DNS_TYPE_A);
    251         r->record_browser_a = avahi_s_record_browser_new(server, interface, protocol, k, flags, record_browser_callback, r);
    252         avahi_key_unref(k);
    253 
    254         if (!r->record_browser_a)
    255             goto fail;
    256     }
    257 
    258     if (aprotocol == AVAHI_PROTO_INET6 || aprotocol == AVAHI_PROTO_UNSPEC) {
    259         k = avahi_key_new(host_name, AVAHI_DNS_CLASS_IN, AVAHI_DNS_TYPE_AAAA);
    260         r->record_browser_aaaa = avahi_s_record_browser_new(server, interface, protocol, k, flags, record_browser_callback, r);
    261         avahi_key_unref(k);
    262 
    263         if (!r->record_browser_aaaa)
    264             goto fail;
    265     }
    266 
    267     assert(r->record_browser_aaaa || r->record_browser_a);
    268 
    269     start_timeout(r);
    270 
    271     return r;
    272 
    273 fail:
    274     avahi_s_host_name_resolver_free(r);
    275     return NULL;
    276 }
    277 
    278 void avahi_s_host_name_resolver_free(AvahiSHostNameResolver *r) {
    279     assert(r);
    280 
    281     AVAHI_LLIST_REMOVE(AvahiSHostNameResolver, resolver, r->server->host_name_resolvers, r);
    282 
    283     if (r->record_browser_a)
    284         avahi_s_record_browser_free(r->record_browser_a);
    285 
    286     if (r->record_browser_aaaa)
    287         avahi_s_record_browser_free(r->record_browser_aaaa);
    288 
    289     if (r->time_event)
    290         avahi_time_event_free(r->time_event);
    291 
    292     if (r->address_record)
    293         avahi_record_unref(r->address_record);
    294 
    295     avahi_free(r->host_name);
    296     avahi_free(r);
    297 }
    298