citadel/modules/c-ares-dns/serv_c-ares-dns.c

   1 /*
   2  * Copyright (c) 1998-2012 by the citadel.org team
   3  *
   4  *  This program is open source software; you can redistribute it and/or modify
   5  *  it under the terms of the GNU General Public License version 3.
   6  *
   7  *
   8  *
   9  *  This program is distributed in the hope that it will be useful,
  10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  *  GNU General Public License for more details.
  13  *
  14  *
  15  *
  16  *
  17  *
  18  *  Inspired by NodeJS.org; thanks for the MX-Parser ;-)
  19  */
  20
  21 #include "sysdep.h"
  22 #include <stdlib.h>
  23 #include <unistd.h>
  24 #include <stdio.h>
  25 #include <termios.h>
  26 #include <fcntl.h>
  27 #include <signal.h>
  28 #include <pwd.h>
  29 #include <errno.h>
  30 #include <sys/types.h>
  31 #include <syslog.h>
  32
  33 #if TIME_WITH_SYS_TIME
  34 # include <sys/time.h>
  35 # include <time.h>
  36 #else
  37 # if HAVE_SYS_TIME_H
  38 #  include <sys/time.h>
  39 # else
  40 #  include <time.h>
  41 # endif
  42 #endif
  43 #include <sys/wait.h>
  44 #include <ctype.h>
  45 #include <string.h>
  46 #include <limits.h>
  47 #include <sys/socket.h>
  48 #include <netinet/in.h>
  49 #include <arpa/inet.h>
  50
  51 #include <libcitadel.h>
  52 #include "citadel.h"
  53 #include "server.h"
  54 #include "citserver.h"
  55 #include "support.h"
  56
  57 #include "ctdl_module.h"
  58 #include "event_client.h"
  59
  60 int DebugCAres = 0;
  61
  62 extern struct ev_loop *event_base;
  63
  64 void SockStateCb(void *data, int sock, int read, int write);
  65
  66
  67 static void HostByAddrCb(void *data,
  68                          int status,
  69                          int timeouts,
  70                          struct hostent *hostent)
  71 {
  72         AsyncIO *IO = data;
  73
  74         EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s\n", __FUNCTION__);
  75         EV_DNS_LOGT_STOP(DNS.timeout);
  76
  77         ev_timer_stop (event_base, &IO->DNS.timeout);
  78
  79         IO->DNS.Query->DNSStatus = status;
  80         if  (status != ARES_SUCCESS) {
  81                 StrBufPlain(IO->ErrMsg, ares_strerror(status), -1);
  82                 return;
  83         }
  84         IO->DNS.Query->Data = hostent;
  85 }
  86
  87 static void ParseAnswerA(AsyncIO *IO, unsigned char* abuf, int alen)
  88 {
  89         struct hostent* host = NULL;
  90
  91         EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s\n", __FUNCTION__);
  92
  93         if (IO->DNS.Query->VParsedDNSReply != NULL)
  94                 IO->DNS.Query->DNSReplyFree(IO->DNS.Query->VParsedDNSReply);
  95         IO->DNS.Query->VParsedDNSReply = NULL;
  96
  97         IO->DNS.Query->DNSStatus = ares_parse_a_reply(abuf,
  98                                                       alen,
  99                                                       &host,
 100                                                       NULL,
 101                                                       NULL);
 102         if (IO->DNS.Query->DNSStatus != ARES_SUCCESS) {
 103                 if (host != NULL)
 104                         ares_free_hostent(host);
 105                 StrBufPlain(IO->ErrMsg,
 106                             ares_strerror(IO->DNS.Query->DNSStatus), -1);
 107                 return;
 108         }
 109         IO->DNS.Query->VParsedDNSReply = host;
 110         IO->DNS.Query->DNSReplyFree = (FreeDNSReply) ares_free_hostent;
 111 }
 112
 113
 114 static void ParseAnswerAAAA(AsyncIO *IO, unsigned char* abuf, int alen)
 115 {
 116         struct hostent* host = NULL;
 117
 118         EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s\n", __FUNCTION__);
 119
 120         if (IO->DNS.Query->VParsedDNSReply != NULL)
 121                 IO->DNS.Query->DNSReplyFree(IO->DNS.Query->VParsedDNSReply);
 122         IO->DNS.Query->VParsedDNSReply = NULL;
 123
 124         IO->DNS.Query->DNSStatus = ares_parse_aaaa_reply(abuf,
 125                                                          alen,
 126                                                          &host,
 127                                                          NULL,
 128                                                          NULL);
 129         if (IO->DNS.Query->DNSStatus != ARES_SUCCESS) {
 130                 if (host != NULL)
 131                         ares_free_hostent(host);
 132                 StrBufPlain(IO->ErrMsg,
 133                             ares_strerror(IO->DNS.Query->DNSStatus), -1);
 134                 return;
 135         }
 136         IO->DNS.Query->VParsedDNSReply = host;
 137         IO->DNS.Query->DNSReplyFree = (FreeDNSReply) ares_free_hostent;
 138 }
 139
 140
 141 static void ParseAnswerCNAME(AsyncIO *IO, unsigned char* abuf, int alen)
 142 {
 143         struct hostent* host = NULL;
 144
 145         EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s\n", __FUNCTION__);
 146
 147         if (IO->DNS.Query->VParsedDNSReply != NULL)
 148                 IO->DNS.Query->DNSReplyFree(IO->DNS.Query->VParsedDNSReply);
 149         IO->DNS.Query->VParsedDNSReply = NULL;
 150
 151         IO->DNS.Query->DNSStatus = ares_parse_a_reply(abuf,
 152                                                       alen,
 153                                                       &host,
 154                                                       NULL,
 155                                                       NULL);
 156         if (IO->DNS.Query->DNSStatus != ARES_SUCCESS) {
 157                 if (host != NULL)
 158                         ares_free_hostent(host);
 159                 StrBufPlain(IO->ErrMsg,
 160                             ares_strerror(IO->DNS.Query->DNSStatus), -1);
 161                 return;
 162         }
 163
 164         // a CNAME lookup always returns a single record but
 165         IO->DNS.Query->VParsedDNSReply = host;
 166         IO->DNS.Query->DNSReplyFree = (FreeDNSReply) ares_free_hostent;
 167 }
 168
 169
 170 static void ParseAnswerMX(AsyncIO *IO, unsigned char* abuf, int alen)
 171 {
 172         struct ares_mx_reply *mx_out = NULL;
 173
 174         EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s\n", __FUNCTION__);
 175
 176         if (IO->DNS.Query->VParsedDNSReply != NULL)
 177                 IO->DNS.Query->DNSReplyFree(IO->DNS.Query->VParsedDNSReply);
 178         IO->DNS.Query->VParsedDNSReply = NULL;
 179
 180         IO->DNS.Query->DNSStatus = ares_parse_mx_reply(abuf, alen, &mx_out);
 181         if (IO->DNS.Query->DNSStatus != ARES_SUCCESS) {
 182                 if (mx_out != NULL)
 183                         ares_free_data(mx_out);
 184                 StrBufPlain(IO->ErrMsg,
 185                             ares_strerror(IO->DNS.Query->DNSStatus), -1);
 186                 return;
 187         }
 188
 189         IO->DNS.Query->VParsedDNSReply = mx_out;
 190         IO->DNS.Query->DNSReplyFree = (FreeDNSReply) ares_free_data;
 191 }
 192
 193
 194 static void ParseAnswerNS(AsyncIO *IO, unsigned char* abuf, int alen)
 195 {
 196         struct hostent* host = NULL;
 197
 198         EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s\n", __FUNCTION__);
 199
 200         if (IO->DNS.Query->VParsedDNSReply != NULL)
 201                 IO->DNS.Query->DNSReplyFree(IO->DNS.Query->VParsedDNSReply);
 202         IO->DNS.Query->VParsedDNSReply = NULL;
 203
 204         IO->DNS.Query->DNSStatus = ares_parse_ns_reply(abuf, alen, &host);
 205         if (IO->DNS.Query->DNSStatus != ARES_SUCCESS) {
 206                 if (host != NULL)
 207                         ares_free_hostent(host);
 208                 StrBufPlain(IO->ErrMsg,
 209                             ares_strerror(IO->DNS.Query->DNSStatus), -1);
 210                 return;
 211         }
 212         IO->DNS.Query->VParsedDNSReply = host;
 213         IO->DNS.Query->DNSReplyFree = (FreeDNSReply) ares_free_hostent;
 214 }
 215
 216
 217 static void ParseAnswerSRV(AsyncIO *IO, unsigned char* abuf, int alen)
 218 {
 219         struct ares_srv_reply *srv_out = NULL;
 220
 221         EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s\n", __FUNCTION__);
 222
 223         if (IO->DNS.Query->VParsedDNSReply != NULL)
 224                 IO->DNS.Query->DNSReplyFree(IO->DNS.Query->VParsedDNSReply);
 225         IO->DNS.Query->VParsedDNSReply = NULL;
 226
 227         IO->DNS.Query->DNSStatus = ares_parse_srv_reply(abuf, alen, &srv_out);
 228         if (IO->DNS.Query->DNSStatus != ARES_SUCCESS) {
 229                 if (srv_out != NULL)
 230                         ares_free_data(srv_out);
 231                 StrBufPlain(IO->ErrMsg,
 232                             ares_strerror(IO->DNS.Query->DNSStatus), -1);
 233                 return;
 234         }
 235
 236         IO->DNS.Query->VParsedDNSReply = srv_out;
 237         IO->DNS.Query->DNSReplyFree = (FreeDNSReply) ares_free_data;
 238 }
 239
 240
 241 static void ParseAnswerTXT(AsyncIO *IO, unsigned char* abuf, int alen)
 242 {
 243         struct ares_txt_reply *txt_out;
 244
 245         EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s\n", __FUNCTION__);
 246
 247         if (IO->DNS.Query->VParsedDNSReply != NULL)
 248                 IO->DNS.Query->DNSReplyFree(IO->DNS.Query->VParsedDNSReply);
 249         IO->DNS.Query->VParsedDNSReply = NULL;
 250
 251         IO->DNS.Query->DNSStatus = ares_parse_txt_reply(abuf, alen, &txt_out);
 252         if (IO->DNS.Query->DNSStatus != ARES_SUCCESS) {
 253                 if (txt_out != NULL)
 254                         ares_free_data(txt_out);
 255                 StrBufPlain(IO->ErrMsg,
 256                             ares_strerror(IO->DNS.Query->DNSStatus), -1);
 257                 return;
 258         }
 259         IO->DNS.Query->VParsedDNSReply = txt_out;
 260         IO->DNS.Query->DNSReplyFree = (FreeDNSReply) ares_free_data;
 261 }
 262
 263 void QueryCb(void *arg,
 264              int status,
 265              int timeouts,
 266              unsigned char* abuf,
 267              int alen)
 268 {
 269         AsyncIO *IO = arg;
 270
 271         EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s\n", __FUNCTION__);
 272         EV_DNS_LOGT_STOP(DNS.timeout);
 273
 274         ev_timer_stop (event_base, &IO->DNS.timeout);
 275
 276         IO->DNS.Query->DNSStatus = status;
 277         if (status == ARES_SUCCESS)
 278                 IO->DNS.Query->DNS_CB(arg, abuf, alen);
 279         else {
 280                 EV_DNS_syslog(LOG_DEBUG, "C-ARES: Failed by: %s error %s\n",
 281                               __FUNCTION__,
 282                               ares_strerror(status));
 283                 StrBufPlain(IO->ErrMsg, ares_strerror(status), -1);
 284                 IO->DNS.Query->DNSStatus = status;
 285         }
 286
 287         ev_idle_init(&IO->unwind_stack,
 288                      IO_postdns_callback);
 289         IO->unwind_stack.data = IO;
 290         EV_DNS_LOGT_INIT(unwind_stack);
 291         EV_DNS_LOGT_START(unwind_stack);
 292         ev_idle_start(event_base, &IO->unwind_stack);
 293 }
 294
 295 void QueryCbDone(AsyncIO *IO)
 296 {
 297         EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s\n", __FUNCTION__);
 298         EV_DNS_LOGT_STOP(DNS.timeout);
 299
 300         ev_idle_stop(event_base, &IO->unwind_stack);
 301 }
 302
 303 void DestructCAres(AsyncIO *IO)
 304 {
 305         EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s\n", __FUNCTION__);
 306         EV_DNS_LOGT_STOP(DNS.timeout);
 307
 308         EV_DNS_LOG_STOP(DNS.recv_event);
 309         ev_io_stop(event_base, &IO->DNS.recv_event);
 310         EV_DNS_LOG_STOP(DNS.send_event);
 311         ev_io_stop(event_base, &IO->DNS.send_event);
 312         ev_timer_stop (event_base, &IO->DNS.timeout);
 313         ev_idle_stop(event_base, &IO->unwind_stack);
 314         ares_destroy_options(&IO->DNS.Options);
 315 }
 316
 317
 318 void InitC_ares_dns(AsyncIO *IO)
 319 {
 320         int optmask = 0;
 321
 322         EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s %p\n", __FUNCTION__, IO->DNS.Channel);
 323
 324         if (IO->DNS.Channel == NULL) {
 325                 optmask |= ARES_OPT_SOCK_STATE_CB;
 326                 IO->DNS.Options.sock_state_cb = SockStateCb;
 327                 IO->DNS.Options.sock_state_cb_data = IO;
 328                 ares_init_options(&IO->DNS.Channel, &IO->DNS.Options, optmask);
 329         }
 330         IO->DNS.Query->DNSStatus = 0;
 331 }
 332
 333 static void
 334 DNStimeouttrigger_callback(struct ev_loop *loop, ev_timer *watcher, int revents)
 335 {
 336         AsyncIO *IO = watcher->data;
 337         struct timeval tv, MaxTV;
 338         struct timeval *NextTV;
 339
 340         memset(&MaxTV, 0, sizeof(MaxTV));
 341         memset(&tv, 0, sizeof(tv));
 342         MaxTV.tv_sec = 30;
 343         NextTV = ares_timeout(IO->DNS.Channel, &MaxTV, &tv);
 344
 345         if ((NextTV->tv_sec != MaxTV.tv_sec) ||
 346             (NextTV->tv_usec != MaxTV.tv_usec))
 347         {
 348                 fd_set readers, writers;
 349                 EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s Timeout!\n", __FUNCTION__);
 350
 351                 FD_ZERO(&readers);
 352                 FD_ZERO(&writers);
 353                 ares_fds(IO->DNS.Channel, &readers, &writers);
 354                 ares_process(IO->DNS.Channel, &readers, &writers);
 355         }
 356 }
 357
 358 void QueueGetHostByNameDone(void *Ctx,
 359                             int status,
 360                             int timeouts,
 361                             struct hostent *hostent)
 362 {
 363         AsyncIO *IO = (AsyncIO *) Ctx;
 364
 365         EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s\n", __FUNCTION__);
 366
 367
 368         IO->DNS.Query->DNSStatus = status;
 369         IO->DNS.Query->VParsedDNSReply = hostent;
 370         IO->DNS.Query->DNSReplyFree = (FreeDNSReply) ares_free_hostent;
 371
 372         ev_idle_init(&IO->unwind_stack,
 373                      IO_postdns_callback);
 374         IO->unwind_stack.data = IO;
 375         EV_DNS_LOGT_INIT(unwind_stack);
 376         EV_DNS_LOGT_START(unwind_stack);
 377         ev_idle_start(event_base, &IO->unwind_stack);
 378         ev_timer_stop (event_base, &IO->DNS.timeout);
 379 }
 380
 381 void QueueGetHostByName(AsyncIO *IO,
 382                         const char *Hostname,
 383                         DNSQueryParts *QueryParts,
 384                         IO_CallBack PostDNS)
 385 {
 386
 387         EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s\n", __FUNCTION__);
 388         IO->DNS.SourcePort = 0;
 389
 390         IO->DNS.Query = QueryParts;
 391         IO->DNS.Query->PostDNS = PostDNS;
 392
 393         InitC_ares_dns(IO);
 394
 395         ev_timer_init(&IO->DNS.timeout, DNStimeouttrigger_callback, 10, 1);
 396         EV_DNS_LOGT_INIT(DNS.timeout);
 397         IO->DNS.timeout.data = IO;
 398         ares_gethostbyname(IO->DNS.Channel,
 399                            Hostname,
 400                            AF_INET6, /* it falls back to ipv4 in doubt... */
 401                            QueueGetHostByNameDone,
 402                            IO);
 403         EV_DNS_LOGT_START(DNS.timeout);
 404         ev_timer_start(event_base, &IO->DNS.timeout);
 405
 406 }
 407
 408 int QueueQuery(ns_type Type,
 409                const char *name,
 410                AsyncIO *IO,
 411                DNSQueryParts *QueryParts,
 412                IO_CallBack PostDNS)
 413 {
 414         int length, family;
 415         char address_b[sizeof(struct in6_addr)];
 416
 417         IO->DNS.SourcePort = 0;
 418
 419         IO->DNS.Query = QueryParts;
 420         IO->DNS.Query->PostDNS = PostDNS;
 421         IO->DNS.Start = IO->Now;
 422
 423         InitC_ares_dns(IO);
 424
 425         ev_timer_init(&IO->DNS.timeout, DNStimeouttrigger_callback, 10, 1);
 426         IO->DNS.timeout.data = IO;
 427         EV_DNS_LOGT_INIT(DNS.timeout);
 428
 429         switch(Type) {
 430         case ns_t_a:
 431                 IO->DNS.Query->DNS_CB = ParseAnswerA;
 432                 break;
 433
 434         case ns_t_aaaa:
 435                 IO->DNS.Query->DNS_CB = ParseAnswerAAAA;
 436                 break;
 437
 438         case ns_t_mx:
 439                 IO->DNS.Query->DNS_CB = ParseAnswerMX;
 440                 break;
 441
 442         case ns_t_ns:
 443                 IO->DNS.Query->DNS_CB = ParseAnswerNS;
 444                 break;
 445
 446         case ns_t_txt:
 447                 IO->DNS.Query->DNS_CB = ParseAnswerTXT;
 448                 break;
 449
 450         case ns_t_srv:
 451                 IO->DNS.Query->DNS_CB = ParseAnswerSRV;
 452                 break;
 453
 454         case ns_t_cname:
 455                 IO->DNS.Query->DNS_CB = ParseAnswerCNAME;
 456                 break;
 457
 458         case ns_t_ptr:
 459
 460
 461                 if (inet_pton(AF_INET, name, &address_b) == 1) {
 462                         length = sizeof(struct in_addr);
 463                         family = AF_INET;
 464                 } else if (inet_pton(AF_INET6, name, &address_b) == 1) {
 465                         length = sizeof(struct in6_addr);
 466                         family = AF_INET6;
 467                 } else {
 468                         return -1;
 469                 }
 470
 471                 ares_gethostbyaddr(IO->DNS.Channel,
 472                                    address_b,
 473                                    length,
 474                                    family,
 475                                    HostByAddrCb,
 476                                    IO);
 477                 EV_DNS_LOGT_START(DNS.timeout);
 478                 ev_timer_start(event_base, &IO->DNS.timeout);
 479
 480                 EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s X1\n", __FUNCTION__);
 481
 482                 return 1;
 483
 484         default:
 485
 486                 EV_DNS_syslog(LOG_DEBUG, "C-ARES: %sX2\n", __FUNCTION__);
 487                 return 0;
 488         }
 489         EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s\n", __FUNCTION__);
 490
 491         ares_query(IO->DNS.Channel, name, ns_c_in, Type, QueryCb, IO);
 492         EV_DNS_LOGT_START(DNS.timeout);
 493         ev_timer_start(event_base, &IO->DNS.timeout);
 494         return 1;
 495 }
 496
 497
 498
 499
 500
 501 /*****************************************************************************
 502  *                      libev / c-ares integration                           *
 503  *****************************************************************************/
 504 static void DNS_send_callback(struct ev_loop *loop, ev_io *watcher, int revents)
 505 {
 506         AsyncIO *IO = watcher->data;
 507
 508         IO->Now = ev_now(event_base);
 509
 510         EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s\n", __FUNCTION__);
 511
 512         ares_process_fd(IO->DNS.Channel,
 513                         ARES_SOCKET_BAD,
 514                         IO->DNS.send_event.fd);
 515 }
 516 static void DNS_recv_callback(struct ev_loop *loop, ev_io *watcher, int revents)
 517 {
 518         AsyncIO *IO = watcher->data;
 519
 520         IO->Now = ev_now(event_base);
 521
 522         EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s\n", __FUNCTION__);
 523
 524         ares_process_fd(IO->DNS.Channel,
 525                         IO->DNS.recv_event.fd,
 526                         ARES_SOCKET_BAD);
 527 }
 528
 529 void SockStateCb(void *data, int sock, int read, int write)
 530 {
 531         AsyncIO *IO = data;
 532 /* already inside of the event queue. */
 533         if (DebugCAres)
 534         {
 535                 struct sockaddr_in sin = {};
 536                 socklen_t slen;
 537                 slen = sizeof(sin);
 538                 if ((IO->DNS.SourcePort == 0) &&
 539                     (getsockname(sock, &sin, &slen) == 0))
 540                 {
 541                         IO->DNS.SourcePort = ntohs(sin.sin_port);
 542                 }
 543                 EV_DNS_syslog(LOG_DEBUG, "C-ARES: %s %d|%d Sock %d port %hu\n",
 544                               __FUNCTION__,
 545                               read,
 546                               write,
 547                               sock,
 548                               IO->DNS.SourcePort);
 549         }
 550
 551         IO->Now = ev_now(event_base);
 552
 553         if (read) {
 554                 if ((IO->DNS.recv_event.fd != sock) &&
 555                     (IO->DNS.recv_event.fd != 0)) {
 556                         EV_DNS_LOG_STOP(DNS.recv_event);
 557                         ev_io_stop(event_base, &IO->DNS.recv_event);
 558                 }
 559                 IO->DNS.recv_event.fd = sock;
 560                 ev_io_init(&IO->DNS.recv_event,
 561                            DNS_recv_callback,
 562                            IO->DNS.recv_event.fd,
 563                            EV_READ);
 564                 EV_DNS_LOG_INIT(DNS.recv_event);
 565                 IO->DNS.recv_event.data = IO;
 566                 EV_DNS_LOG_START(DNS.recv_event);
 567                 ev_io_start(event_base, &IO->DNS.recv_event);
 568         }
 569         if (write) {
 570                 if ((IO->DNS.send_event.fd != sock) &&
 571                     (IO->DNS.send_event.fd != 0)) {
 572                         EV_DNS_LOG_STOP(DNS.send_event);
 573                         ev_io_stop(event_base, &IO->DNS.send_event);
 574                 }
 575                 IO->DNS.send_event.fd = sock;
 576                 ev_io_init(&IO->DNS.send_event,
 577                            DNS_send_callback,
 578                            IO->DNS.send_event.fd,
 579                            EV_WRITE);
 580                 IO->DNS.send_event.data = IO;
 581                 EV_DNS_LOG_INIT(DNS.send_event);
 582                 EV_DNS_LOG_START(DNS.send_event);
 583                 ev_io_start(event_base, &IO->DNS.send_event);
 584         }
 585         if ((read == 0) && (write == 0)) {
 586                 EV_DNS_LOG_STOP(DNS.recv_event);
 587                 EV_DNS_LOG_STOP(DNS.send_event);
 588                 ev_io_stop(event_base, &IO->DNS.recv_event);
 589                 ev_io_stop(event_base, &IO->DNS.send_event);
 590         }
 591 }
 592 void EnableDebugCAres(const int n)
 593 {
 594         DebugCAres = n;
 595 }
 596
 597 CTDL_MODULE_INIT(c_ares_client)
 598 {
 599         if (!threading)
 600         {
 601                 CtdlRegisterDebugFlagHook(HKEY("cares"), EnableDebugCAres, &DebugCAres);
 602                 int r = ares_library_init(ARES_LIB_INIT_ALL);
 603                 if (0 != r) {
 604
 605                 }
 606         }
 607         return "c-ares";
 608 }