gweb/gresolv.c

   1 /*
   2  *
   3  *  Resolver library with GLib integration
   4  *
   5  *  Copyright (C) 2009-2010  Intel Corporation. All rights reserved.
   6  *
   7  *  This program is free software; you can redistribute it and/or modify
   8  *  it under the terms of the GNU General Public License version 2 as
   9  *  published by the Free Software Foundation.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  19  *
  20  */
  21
  22 #ifdef HAVE_CONFIG_H
  23 #include <config.h>
  24 #endif
  25
  26 #include <errno.h>
  27 #include <unistd.h>
  28 #include <stdarg.h>
  29 #include <string.h>
  30 #include <resolv.h>
  31 #include <sys/socket.h>
  32 #include <arpa/inet.h>
  33 #include <arpa/nameser.h>
  34
  35 #include "gresolv.h"
  36
  37 struct resolv_query {
  38         GResolv *resolv;
  39
  40         guint id;
  41         guint timeout;
  42
  43         uint16_t msgid;
  44
  45         GResolvResultFunc result_func;
  46         gpointer result_data;
  47 };
  48
  49 struct resolv_nameserver {
  50         GResolv *resolv;
  51
  52         char *address;
  53         uint16_t port;
  54         unsigned long flags;
  55
  56         GIOChannel *udp_channel;
  57         guint udp_watch;
  58 };
  59
  60 struct _GResolv {
  61         gint ref_count;
  62
  63         guint next_query_id;
  64         GQueue *query_queue;
  65
  66         int index;
  67         GList *nameserver_list;
  68
  69         struct __res_state res;
  70
  71         GResolvDebugFunc debug_func;
  72         gpointer debug_data;
  73 };
  74
  75 static inline void debug(GResolv *resolv, const char *format, ...)
  76 {
  77         char str[256];
  78         va_list ap;
  79
  80         if (resolv->debug_func == NULL)
  81                 return;
  82
  83         va_start(ap, format);
  84
  85         if (vsnprintf(str, sizeof(str), format, ap) > 0)
  86                 resolv->debug_func(str, resolv->debug_data);
  87
  88         va_end(ap);
  89 }
  90
  91 static void destroy_query(struct resolv_query *query)
  92 {
  93         if (query->timeout > 0)
  94                 g_source_remove(query->timeout);
  95
  96         g_free(query);
  97 }
  98
  99 static gboolean query_timeout(gpointer user_data)
 100 {
 101         struct resolv_query *query = user_data;
 102         GResolv *resolv = query->resolv;
 103
 104         query->timeout = 0;
 105
 106         if (query->result_func != NULL)
 107                 query->result_func(G_RESOLV_RESULT_STATUS_NO_RESPONSE,
 108                                                 NULL, query->result_data);
 109
 110         destroy_query(query);
 111         g_queue_remove(resolv->query_queue, query);
 112
 113         return FALSE;
 114 }
 115
 116 static void free_nameserver(struct resolv_nameserver *nameserver)
 117 {
 118         if (nameserver == NULL)
 119                 return;
 120
 121         if (nameserver->udp_watch > 0)
 122                 g_source_remove(nameserver->udp_watch);
 123
 124         if (nameserver->udp_channel != NULL)
 125                 g_io_channel_unref(nameserver->udp_channel);
 126
 127         g_free(nameserver->address);
 128         g_free(nameserver);
 129 }
 130
 131 static void flush_nameservers(GResolv *resolv)
 132 {
 133         GList *list;
 134
 135         for (list = g_list_first(resolv->nameserver_list);
 136                                         list; list = g_list_next(list))
 137                 free_nameserver(list->data);
 138
 139         g_list_free(resolv->nameserver_list);
 140         resolv->nameserver_list = NULL;
 141 }
 142
 143 static int send_query(GResolv *resolv, const unsigned char *buf, int len)
 144 {
 145         GList *list;
 146
 147         if (resolv->nameserver_list == NULL)
 148                 return -ENOENT;
 149
 150         for (list = g_list_first(resolv->nameserver_list);
 151                                         list; list = g_list_next(list)) {
 152                 struct resolv_nameserver *nameserver = list->data;
 153                 int sk, sent;
 154
 155                 if (nameserver->udp_channel == NULL)
 156                         continue;
 157
 158                 sk = g_io_channel_unix_get_fd(nameserver->udp_channel);
 159
 160                 sent = send(sk, buf, len, 0);
 161         }
 162
 163         return 0;
 164 }
 165
 166 static gint compare_query_id(gconstpointer a, gconstpointer b)
 167 {
 168         const struct resolv_query *query = a;
 169         guint id = GPOINTER_TO_UINT(b);
 170
 171         if (query->id < id)
 172                 return -1;
 173
 174         if (query->id > id)
 175                 return 1;
 176
 177         return 0;
 178 }
 179
 180 static gint compare_query_msgid(gconstpointer a, gconstpointer b)
 181 {
 182         const struct resolv_query *query = a;
 183         uint16_t msgid = GPOINTER_TO_UINT(b);
 184
 185         if (query->msgid < msgid)
 186                 return -1;
 187
 188         if (query->msgid > msgid)
 189                 return 1;
 190
 191         return 0;
 192 }
 193
 194 static void parse_response(struct resolv_nameserver *nameserver,
 195                                         const unsigned char *buf, int len)
 196 {
 197         GResolv *resolv = nameserver->resolv;
 198         GResolvResultStatus status;
 199         GList *list;
 200         char **results;
 201         ns_msg msg;
 202         ns_rr rr;
 203         int i, n, rcode, count;
 204
 205         debug(resolv, "response from %s", nameserver->address);
 206
 207         ns_initparse(buf, len, &msg);
 208
 209         rcode = ns_msg_getflag(msg, ns_f_rcode);
 210         count = ns_msg_count(msg, ns_s_an);
 211
 212         debug(resolv, "msg id: 0x%04x rcode: %d count: %d",
 213                                         ns_msg_id(msg), rcode, count);
 214
 215         switch (rcode) {
 216         case 0:
 217                 status = G_RESOLV_RESULT_STATUS_SUCCESS;
 218                 break;
 219         case 1:
 220                 status = G_RESOLV_RESULT_STATUS_FORMAT_ERROR;
 221                 break;
 222         case 2:
 223                 status = G_RESOLV_RESULT_STATUS_SERVER_FAILURE;
 224                 break;
 225         case 3:
 226                 status = G_RESOLV_RESULT_STATUS_NAME_ERROR;
 227                 break;
 228         case 4:
 229                 status = G_RESOLV_RESULT_STATUS_NOT_IMPLEMENTED;
 230                 break;
 231         case 5:
 232                 status = G_RESOLV_RESULT_STATUS_REFUSED;
 233                 break;
 234         default:
 235                 status = G_RESOLV_RESULT_STATUS_ERROR;
 236                 break;
 237         }
 238
 239         results = g_try_new(char *, count + 1);
 240         if (results == NULL)
 241                 return;
 242
 243         for (i = 0, n = 0; i < count; i++) {
 244                 char result[100];
 245
 246                 ns_parserr(&msg, ns_s_an, i, &rr);
 247
 248                 if (ns_rr_class(rr) != ns_c_in)
 249                         continue;
 250
 251                 if (ns_rr_type(rr) != ns_t_a)
 252                         continue;
 253
 254                 if (ns_rr_rdlen(rr) != NS_INADDRSZ)
 255                         continue;
 256
 257                 inet_ntop(AF_INET, ns_rr_rdata(rr), result, sizeof(result));
 258
 259                 results[n++] = g_strdup(result);
 260         }
 261
 262         results[n] = NULL;
 263
 264         list = g_queue_find_custom(resolv->query_queue,
 265                         GUINT_TO_POINTER(ns_msg_id(msg)), compare_query_msgid);
 266
 267         if (list != NULL) {
 268                 struct resolv_query *query = list->data;
 269
 270                 if (query->result_func != NULL)
 271                         query->result_func(status, results,
 272                                                 query->result_data);
 273
 274                 destroy_query(query);
 275                 g_queue_remove(resolv->query_queue, query);
 276         }
 277
 278         g_strfreev(results);
 279 }
 280
 281 static gboolean received_udp_data(GIOChannel *channel, GIOCondition cond,
 282                                                         gpointer user_data)
 283 {
 284         struct resolv_nameserver *nameserver = user_data;
 285         unsigned char buf[4096];
 286         int sk, len;
 287
 288         if (cond & (G_IO_NVAL | G_IO_ERR | G_IO_HUP)) {
 289                 nameserver->udp_watch = 0;
 290                 return FALSE;
 291         }
 292
 293         sk = g_io_channel_unix_get_fd(nameserver->udp_channel);
 294
 295         len = recv(sk, buf, sizeof(buf), 0);
 296         if (len < 12)
 297                 return TRUE;
 298
 299         parse_response(nameserver, buf, len);
 300
 301         return TRUE;
 302 }
 303
 304 static int connect_udp_channel(struct resolv_nameserver *nameserver)
 305 {
 306         struct sockaddr_in sin;
 307         int sk;
 308
 309         sk = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
 310         if (sk < 0)
 311                 return -EIO;
 312
 313         memset(&sin, 0, sizeof(sin));
 314         sin.sin_family = AF_INET;
 315         sin.sin_port = htons(nameserver->port);
 316         sin.sin_addr.s_addr = inet_addr(nameserver->address);
 317
 318         if (connect(sk, (struct sockaddr *) &sin, sizeof(sin)) < 0) {
 319                 close(sk);
 320                 return -EIO;
 321         }
 322
 323         nameserver->udp_channel = g_io_channel_unix_new(sk);
 324         if (nameserver->udp_channel == NULL) {
 325                 close(sk);
 326                 return -ENOMEM;
 327         }
 328
 329         g_io_channel_set_close_on_unref(nameserver->udp_channel, TRUE);
 330
 331         nameserver->udp_watch = g_io_add_watch(nameserver->udp_channel,
 332                                                 G_IO_IN, received_udp_data,
 333                                                                 nameserver);
 334
 335         return 0;
 336 }
 337
 338 GResolv *g_resolv_new(int index)
 339 {
 340         GResolv *resolv;
 341
 342         if (index < 0)
 343                 return NULL;
 344
 345         resolv = g_try_new0(GResolv, 1);
 346         if (resolv == NULL)
 347                 return NULL;
 348
 349         resolv->ref_count = 1;
 350
 351         resolv->next_query_id = 1;
 352         resolv->query_queue = g_queue_new();
 353
 354         if (resolv->query_queue == NULL) {
 355                 g_free(resolv);
 356                 return NULL;
 357         }
 358
 359         resolv->index = index;
 360         resolv->nameserver_list = NULL;
 361
 362         res_ninit(&resolv->res);
 363
 364         return resolv;
 365 }
 366
 367 GResolv *g_resolv_ref(GResolv *resolv)
 368 {
 369         if (resolv == NULL)
 370                 return NULL;
 371
 372         g_atomic_int_inc(&resolv->ref_count);
 373
 374         return resolv;
 375 }
 376
 377 void g_resolv_unref(GResolv *resolv)
 378 {
 379         struct resolv_query *query;
 380
 381         if (resolv == NULL)
 382                 return;
 383
 384         if (g_atomic_int_dec_and_test(&resolv->ref_count) == FALSE)
 385                 return;
 386
 387         while ((query = g_queue_pop_head(resolv->query_queue)))
 388                 destroy_query(query);
 389
 390         g_queue_free(resolv->query_queue);
 391
 392         flush_nameservers(resolv);
 393
 394         res_nclose(&resolv->res);
 395
 396         g_free(resolv);
 397 }
 398
 399 void g_resolv_set_debug(GResolv *resolv,
 400                                 GResolvDebugFunc func, gpointer user_data)
 401 {
 402         if (resolv == NULL)
 403                 return;
 404
 405         resolv->debug_func = func;
 406         resolv->debug_data = user_data;
 407 }
 408
 409 gboolean g_resolv_add_nameserver(GResolv *resolv, const char *address,
 410                                         uint16_t port, unsigned long flags)
 411 {
 412         struct resolv_nameserver *nameserver;
 413
 414         if (resolv == NULL)
 415                 return FALSE;
 416
 417         nameserver = g_try_new0(struct resolv_nameserver, 1);
 418         if (nameserver == NULL)
 419                 return FALSE;
 420
 421         nameserver->address = g_strdup(address);
 422         nameserver->port = port;
 423         nameserver->flags = flags;
 424
 425         if (connect_udp_channel(nameserver) < 0) {
 426                 free_nameserver(nameserver);
 427                 return FALSE;
 428         }
 429
 430         nameserver->resolv = resolv;
 431
 432         resolv->nameserver_list = g_list_append(resolv->nameserver_list,
 433                                                                 nameserver);
 434
 435         debug(resolv, "setting nameserver %s", address);
 436
 437         return TRUE;
 438 }
 439
 440 void g_resolv_flush_nameservers(GResolv *resolv)
 441 {
 442         if (resolv == NULL)
 443                 return;
 444
 445         flush_nameservers(resolv);
 446 }
 447
 448 guint g_resolv_lookup_hostname(GResolv *resolv, const char *hostname,
 449                                 GResolvResultFunc func, gpointer user_data)
 450 {
 451         struct resolv_query *query;
 452         unsigned char buf[4096];
 453         int len;
 454
 455         debug(resolv, "lookup hostname %s", hostname);
 456
 457         if (resolv == NULL)
 458                 return 0;
 459
 460         if (resolv->nameserver_list == NULL) {
 461                 int i;
 462
 463                 for (i = 0; i < resolv->res.nscount; i++) {
 464                         struct sockaddr_in *addr = &resolv->res.nsaddr_list[i];
 465                         g_resolv_add_nameserver(resolv,
 466                                         inet_ntoa(addr->sin_addr), 53, 0);
 467                 }
 468
 469                 if (resolv->nameserver_list == NULL)
 470                         g_resolv_add_nameserver(resolv, "127.0.0.1", 53, 0);
 471         }
 472
 473         query = g_try_new0(struct resolv_query, 1);
 474         if (query == NULL)
 475                 return 0;
 476
 477         query->id = resolv->next_query_id++;
 478
 479         len = res_mkquery(ns_o_query, hostname, ns_c_in, ns_t_a,
 480                                         NULL, 0, NULL, buf, sizeof(buf));
 481
 482         query->msgid = buf[0] << 8 | buf[1];
 483
 484         query->result_func = func;
 485         query->result_data = user_data;
 486
 487         if (send_query(resolv, buf, len) < 0) {
 488                 g_free(query);
 489                 return -EIO;
 490         }
 491
 492         query->resolv = resolv;
 493
 494         g_queue_push_tail(resolv->query_queue, query);
 495
 496         query->timeout = g_timeout_add_seconds(5, query_timeout, query);
 497
 498         return query->id;
 499 }
 500
 501 gboolean g_resolv_cancel_lookup(GResolv *resolv, guint id)
 502 {
 503         GList *list;
 504
 505         list = g_queue_find_custom(resolv->query_queue,
 506                                 GUINT_TO_POINTER(id), compare_query_id);
 507
 508         if (list == NULL)
 509                 return FALSE;
 510
 511         destroy_query(list->data);
 512         g_queue_remove(resolv->query_queue, list->data);
 513
 514         return TRUE;
 515 }