plugins/check_dns.c

   1 /*****************************************************************************
   2 *
   3 * Nagios check_dns plugin
   4 *
   5 * License: GPL
   6 * Copyright (c) 2000-2008 Nagios Plugins Development Team
   7 *
   8 * Last Modified: $Date$
   9 *
  10 * Description:
  11 *
  12 * This file contains the check_dns plugin
  13 *
  14 * LIMITATION: nslookup on Solaris 7 can return output over 2 lines, which
  15 * will not be picked up by this plugin
  16 *
  17 *
  18 * This program is free software: you can redistribute it and/or modify
  19 * it under the terms of the GNU General Public License as published by
  20 * the Free Software Foundation, either version 3 of the License, or
  21 * (at your option) any later version.
  22 *
  23 * This program is distributed in the hope that it will be useful,
  24 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  25 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  26 * GNU General Public License for more details.
  27 *
  28 * You should have received a copy of the GNU General Public License
  29 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  30 *
  31 * $Id$
  32 *
  33 *****************************************************************************/
  34
  35 const char *progname = "check_dns";
  36 const char *revision = "$Revision$";
  37 const char *copyright = "2000-2008";
  38 const char *email = "nagiosplug-devel@lists.sourceforge.net";
  39
  40 #include "common.h"
  41 #include "utils.h"
  42 #include "utils_base.h"
  43 #include "netutils.h"
  44 #include "runcmd.h"
  45
  46 int process_arguments (int, char **);
  47 int validate_arguments (void);
  48 int error_scan (char *);
  49 void print_help (void);
  50 void print_usage (void);
  51
  52 #define ADDRESS_LENGTH 256
  53 char query_address[ADDRESS_LENGTH] = "";
  54 char dns_server[ADDRESS_LENGTH] = "";
  55 char ptr_server[ADDRESS_LENGTH] = "";
  56 int verbose = FALSE;
  57 char **expected_address = NULL;
  58 int expected_address_cnt = 0;
  59
  60 int expect_authority = FALSE;
  61 thresholds *time_thresholds = NULL;
  62
  63 static int
  64 qstrcmp(const void *p1, const void *p2)
  65 {
  66         /* The actual arguments to this function are "pointers to
  67            pointers to char", but strcmp() arguments are "pointers
  68            to char", hence the following cast plus dereference */
  69         return strcmp(* (char * const *) p1, * (char * const *) p2);
  70 }
  71
  72
  73 int
  74 main (int argc, char **argv)
  75 {
  76   char *command_line = NULL;
  77   char input_buffer[MAX_INPUT_BUFFER];
  78   char *address = NULL; /* comma seperated str with addrs/ptrs (sorted) */
  79   char **addresses = NULL;
  80   int n_addresses = 0;
  81   char *msg = NULL;
  82   char *temp_buffer = NULL;
  83   int non_authoritative = FALSE;
  84   int result = STATE_UNKNOWN;
  85   double elapsed_time;
  86   long microsec;
  87   struct timeval tv;
  88   int multi_address;
  89   int parse_address = FALSE; /* This flag scans for Address: but only after Name: */
  90   output chld_out, chld_err;
  91   size_t i;
  92
  93   setlocale (LC_ALL, "");
  94   bindtextdomain (PACKAGE, LOCALEDIR);
  95   textdomain (PACKAGE);
  96
  97   /* Set signal handling and alarm */
  98   if (signal (SIGALRM, popen_timeout_alarm_handler) == SIG_ERR) {
  99     usage_va(_("Cannot catch SIGALRM"));
 100   }
 101
 102   /* Parse extra opts if any */
 103   argv=np_extra_opts (&argc, argv, progname);
 104
 105   if (process_arguments (argc, argv) == ERROR) {
 106     usage_va(_("Could not parse arguments"));
 107   }
 108
 109   /* get the command to run */
 110   asprintf (&command_line, "%s %s %s", NSLOOKUP_COMMAND, query_address, dns_server);
 111
 112   alarm (timeout_interval);
 113   gettimeofday (&tv, NULL);
 114
 115   if (verbose)
 116     printf ("%s\n", command_line);
 117
 118   /* run the command */
 119   if((np_runcmd(command_line, &chld_out, &chld_err, 0)) != 0) {
 120     msg = (char *)_("nslookup returned an error status");
 121     result = STATE_WARNING;
 122   }
 123
 124   /* scan stdout */
 125   for(i = 0; i < chld_out.lines; i++) {
 126     if (addresses == NULL)
 127       addresses = malloc(sizeof(*addresses)*10);
 128     else if (!(n_addresses % 10))
 129       addresses = realloc(addresses,sizeof(*addresses) * (n_addresses + 10));
 130
 131     if (verbose)
 132       puts(chld_out.line[i]);
 133
 134     if (strstr (chld_out.line[i], ".in-addr.arpa")) {
 135       if ((temp_buffer = strstr (chld_out.line[i], "name = ")))
 136         addresses[n_addresses++] = strdup (temp_buffer + 7);
 137       else {
 138         msg = (char *)_("Warning plugin error");
 139         result = STATE_WARNING;
 140       }
 141     }
 142
 143     /* the server is responding, we just got the host name... */
 144     if (strstr (chld_out.line[i], "Name:"))
 145       parse_address = TRUE;
 146     else if (parse_address == TRUE && (strstr (chld_out.line[i], "Address:") ||
 147              strstr (chld_out.line[i], "Addresses:"))) {
 148       temp_buffer = index (chld_out.line[i], ':');
 149       temp_buffer++;
 150
 151       /* Strip leading spaces */
 152       for (; *temp_buffer != '\0' && *temp_buffer == ' '; temp_buffer++)
 153         /* NOOP */;
 154
 155       strip(temp_buffer);
 156       if (temp_buffer==NULL || strlen(temp_buffer)==0) {
 157         die (STATE_CRITICAL,
 158              _("DNS CRITICAL - '%s' returned empty host name string\n"),
 159              NSLOOKUP_COMMAND);
 160       }
 161
 162       addresses[n_addresses++] = strdup(temp_buffer);
 163     }
 164     else if (strstr (chld_out.line[i], _("Non-authoritative answer:"))) {
 165       non_authoritative = TRUE;
 166     }
 167
 168
 169     result = error_scan (chld_out.line[i]);
 170     if (result != STATE_OK) {
 171       msg = strchr (chld_out.line[i], ':');
 172       if(msg) msg++;
 173       break;
 174     }
 175   }
 176
 177   /* scan stderr */
 178   for(i = 0; i < chld_err.lines; i++) {
 179     if (verbose)
 180       puts(chld_err.line[i]);
 181
 182     if (error_scan (chld_err.line[i]) != STATE_OK) {
 183       result = max_state (result, error_scan (chld_err.line[i]));
 184       msg = strchr(input_buffer, ':');
 185       if(msg) msg++;
 186     }
 187   }
 188
 189   if (addresses) {
 190     int i,slen;
 191     char *adrp;
 192     qsort(addresses, n_addresses, sizeof(*addresses), qstrcmp);
 193     for(i=0, slen=1; i < n_addresses; i++) {
 194       slen += strlen(addresses[i])+1;
 195     }
 196     adrp = address = malloc(slen);
 197     for(i=0; i < n_addresses; i++) {
 198       if (i) *adrp++ = ',';
 199       strcpy(adrp, addresses[i]);
 200       adrp += strlen(addresses[i]);
 201     }
 202     *adrp = 0;
 203   } else
 204     die (STATE_CRITICAL,
 205          _("DNS CRITICAL - '%s' msg parsing exited with no address\n"),
 206          NSLOOKUP_COMMAND);
 207
 208   /* compare to expected address */
 209   if (result == STATE_OK && expected_address_cnt > 0) {
 210     result = STATE_CRITICAL;
 211     temp_buffer = "";
 212     for (i=0; i<expected_address_cnt; i++) {
 213       /* check if we get a match and prepare an error string */
 214       if (strcmp(address, expected_address[i]) == 0) result = STATE_OK;
 215       asprintf(&temp_buffer, "%s%s; ", temp_buffer, expected_address[i]);
 216     }
 217     if (result == STATE_CRITICAL) {
 218       /* Strip off last semicolon... */
 219       temp_buffer[strlen(temp_buffer)-2] = '\0';
 220       asprintf(&msg, _("expected '%s' but got '%s'"), temp_buffer, address);
 221     }
 222   }
 223
 224   /* check if authoritative */
 225   if (result == STATE_OK && expect_authority && non_authoritative) {
 226     result = STATE_CRITICAL;
 227     asprintf(&msg, _("server %s is not authoritative for %s"), dns_server, query_address);
 228   }
 229
 230   microsec = deltime (tv);
 231   elapsed_time = (double)microsec / 1.0e6;
 232
 233   if (result == STATE_OK) {
 234     if (strchr (address, ',') == NULL)
 235       multi_address = FALSE;
 236     else
 237       multi_address = TRUE;
 238
 239     result = get_status(elapsed_time, time_thresholds);
 240     if (result == STATE_OK) {
 241       printf ("DNS %s: ", _("OK"));
 242     } else if (result == STATE_WARNING) {
 243       printf ("DNS %s: ", _("WARNING"));
 244     } else if (result == STATE_CRITICAL) {
 245       printf ("DNS %s: ", _("CRITICAL"));
 246     }
 247     printf (ngettext("%.3f second response time", "%.3f seconds response time", elapsed_time), elapsed_time);
 248     printf (_(". %s returns %s"), query_address, address);
 249     printf ("|%s\n", fperfdata ("time", elapsed_time, "s", FALSE, 0, FALSE, 0, TRUE, 0, FALSE, 0));
 250   }
 251   else if (result == STATE_WARNING)
 252     printf (_("DNS WARNING - %s\n"),
 253             !strcmp (msg, "") ? _(" Probably a non-existent host/domain") : msg);
 254   else if (result == STATE_CRITICAL)
 255     printf (_("DNS CRITICAL - %s\n"),
 256             !strcmp (msg, "") ? _(" Probably a non-existent host/domain") : msg);
 257   else
 258     printf (_("DNS UNKNOW - %s\n"),
 259             !strcmp (msg, "") ? _(" Probably a non-existent host/domain") : msg);
 260
 261   return result;
 262 }
 263
 264
 265
 266 int
 267 error_scan (char *input_buffer)
 268 {
 269
 270   /* the DNS lookup timed out */
 271   if (strstr (input_buffer, _("Note: nslookup is deprecated and may be removed from future releases.")) ||
 272       strstr (input_buffer, _("Consider using the `dig' or `host' programs instead.  Run nslookup with")) ||
 273       strstr (input_buffer, _("the `-sil[ent]' option to prevent this message from appearing.")))
 274     return STATE_OK;
 275
 276   /* DNS server is not running... */
 277   else if (strstr (input_buffer, "No response from server"))
 278     die (STATE_CRITICAL, _("No response from DNS %s\n"), dns_server);
 279
 280   /* Host name is valid, but server doesn't have records... */
 281   else if (strstr (input_buffer, "No records"))
 282     die (STATE_CRITICAL, _("DNS %s has no records\n"), dns_server);
 283
 284   /* Connection was refused */
 285   else if (strstr (input_buffer, "Connection refused") ||
 286      strstr (input_buffer, "Couldn't find server") ||
 287            strstr (input_buffer, "Refused") ||
 288            (strstr (input_buffer, "** server can't find") &&
 289             strstr (input_buffer, ": REFUSED")))
 290     die (STATE_CRITICAL, _("Connection to DNS %s was refused\n"), dns_server);
 291
 292   /* Query refused (usually by an ACL in the namserver) */
 293   else if (strstr (input_buffer, "Query refused"))
 294     die (STATE_CRITICAL, _("Query was refused by DNS server at %s\n"), dns_server);
 295
 296   /* No information (e.g. nameserver IP has two PTR records) */
 297   else if (strstr (input_buffer, "No information"))
 298     die (STATE_CRITICAL, _("No information returned by DNS server at %s\n"), dns_server);
 299
 300   /* Host or domain name does not exist */
 301   else if (strstr (input_buffer, "Non-existent") ||
 302            strstr (input_buffer, "** server can't find") ||
 303      strstr (input_buffer,"NXDOMAIN"))
 304     die (STATE_CRITICAL, _("Domain %s was not found by the server\n"), query_address);
 305
 306   /* Network is unreachable */
 307   else if (strstr (input_buffer, "Network is unreachable"))
 308     die (STATE_CRITICAL, _("Network is unreachable\n"));
 309
 310   /* Internal server failure */
 311   else if (strstr (input_buffer, "Server failure"))
 312     die (STATE_CRITICAL, _("DNS failure for %s\n"), dns_server);
 313
 314   /* Request error or the DNS lookup timed out */
 315   else if (strstr (input_buffer, "Format error") ||
 316            strstr (input_buffer, "Timed out"))
 317     return STATE_WARNING;
 318
 319   return STATE_OK;
 320
 321 }
 322
 323
 324 /* process command-line arguments */
 325 int
 326 process_arguments (int argc, char **argv)
 327 {
 328   int c;
 329   char *warning = NULL;
 330   char *critical = NULL;
 331
 332   int opt_index = 0;
 333   static struct option long_opts[] = {
 334     {"help", no_argument, 0, 'h'},
 335     {"version", no_argument, 0, 'V'},
 336     {"verbose", no_argument, 0, 'v'},
 337     {"timeout", required_argument, 0, 't'},
 338     {"hostname", required_argument, 0, 'H'},
 339     {"server", required_argument, 0, 's'},
 340     {"reverse-server", required_argument, 0, 'r'},
 341     {"expected-address", required_argument, 0, 'a'},
 342     {"expect-authority", no_argument, 0, 'A'},
 343     {"warning", no_argument, 0, 'w'},
 344     {"critical", no_argument, 0, 'c'},
 345     {0, 0, 0, 0}
 346   };
 347
 348   if (argc < 2)
 349     return ERROR;
 350
 351   for (c = 1; c < argc; c++)
 352     if (strcmp ("-to", argv[c]) == 0)
 353       strcpy (argv[c], "-t");
 354
 355   while (1) {
 356     c = getopt_long (argc, argv, "hVvAt:H:s:r:a:w:c:", long_opts, &opt_index);
 357
 358     if (c == -1 || c == EOF)
 359       break;
 360
 361     switch (c) {
 362     case 'h': /* help */
 363       print_help ();
 364       exit (STATE_OK);
 365     case 'V': /* version */
 366       print_revision (progname, revision);
 367       exit (STATE_OK);
 368     case 'v': /* version */
 369       verbose = TRUE;
 370       break;
 371     case 't': /* timeout period */
 372       timeout_interval = atoi (optarg);
 373       break;
 374     case 'H': /* hostname */
 375       if (strlen (optarg) >= ADDRESS_LENGTH)
 376         die (STATE_UNKNOWN, _("Input buffer overflow\n"));
 377       strcpy (query_address, optarg);
 378       break;
 379     case 's': /* server name */
 380       /* TODO: this host_or_die check is probably unnecessary.
 381        * Better to confirm nslookup response matches */
 382       host_or_die(optarg);
 383       if (strlen (optarg) >= ADDRESS_LENGTH)
 384         die (STATE_UNKNOWN, _("Input buffer overflow\n"));
 385       strcpy (dns_server, optarg);
 386       break;
 387     case 'r': /* reverse server name */
 388       /* TODO: Is this host_or_die necessary? */
 389       host_or_die(optarg);
 390       if (strlen (optarg) >= ADDRESS_LENGTH)
 391         die (STATE_UNKNOWN, _("Input buffer overflow\n"));
 392       strcpy (ptr_server, optarg);
 393       break;
 394     case 'a': /* expected address */
 395       if (strlen (optarg) >= ADDRESS_LENGTH)
 396         die (STATE_UNKNOWN, _("Input buffer overflow\n"));
 397       expected_address = (char **)realloc(expected_address, (expected_address_cnt+1) * sizeof(char**));
 398       expected_address[expected_address_cnt] = strdup(optarg);
 399       expected_address_cnt++;
 400       break;
 401     case 'A': /* expect authority */
 402       expect_authority = TRUE;
 403       break;
 404     case 'w':
 405       warning = optarg;
 406       break;
 407     case 'c':
 408       critical = optarg;
 409       break;
 410     default: /* args not parsable */
 411       usage5();
 412     }
 413   }
 414
 415   c = optind;
 416   if (strlen(query_address)==0 && c<argc) {
 417     if (strlen(argv[c])>=ADDRESS_LENGTH)
 418       die (STATE_UNKNOWN, _("Input buffer overflow\n"));
 419     strcpy (query_address, argv[c++]);
 420   }
 421
 422   if (strlen(dns_server)==0 && c<argc) {
 423     /* TODO: See -s option */
 424     host_or_die(argv[c]);
 425     if (strlen(argv[c]) >= ADDRESS_LENGTH)
 426       die (STATE_UNKNOWN, _("Input buffer overflow\n"));
 427     strcpy (dns_server, argv[c++]);
 428   }
 429
 430   set_thresholds(&time_thresholds, warning, critical);
 431
 432   return validate_arguments ();
 433 }
 434
 435
 436 int
 437 validate_arguments ()
 438 {
 439   if (query_address[0] == 0)
 440     return ERROR;
 441
 442   return OK;
 443 }
 444
 445
 446 void
 447 print_help (void)
 448 {
 449   print_revision (progname, revision);
 450
 451   printf ("Copyright (c) 1999 Ethan Galstad <nagios@nagios.org>\n");
 452   printf (COPYRIGHT, copyright, email);
 453
 454   printf ("%s\n", _("This plugin uses the nslookup program to obtain the IP address for the given host/domain query."));
 455   printf ("%s\n", _("An optional DNS server to use may be specified."));
 456   printf ("%s\n", _("If no DNS server is specified, the default server(s) specified in /etc/resolv.conf will be used."));
 457
 458   printf ("\n\n");
 459
 460   print_usage ();
 461
 462   printf (_(UT_HELP_VRSN));
 463   printf (_(UT_EXTRA_OPTS));
 464
 465   printf (" -H, --hostname=HOST\n");
 466   printf ("    %s\n", _("The name or address you want to query"));
 467   printf (" -s, --server=HOST\n");
 468   printf ("    %s\n", _("Optional DNS server you want to use for the lookup"));
 469   printf (" -a, --expected-address=IP-ADDRESS|HOST\n");
 470   printf ("    %s\n", _("Optional IP-ADDRESS you expect the DNS server to return. HOST must end with"));
 471   printf ("    %s\n", _("a dot (.). This option can be repeated multiple times (Returns OK if any"));
 472   printf ("    %s\n", _("value match). If multiple addresses are returned at once, you have to match"));
 473   printf ("    %s\n", _("the whole string of addresses separated with commas (sorted alphabetically)."));
 474   printf (" -A, --expect-authority\n");
 475   printf ("    %s\n", _("Optionally expect the DNS server to be authoritative for the lookup"));
 476   printf (" -w, --warning=seconds\n");
 477   printf ("    %s\n", _("Return warning if elapsed time exceeds value. Default off"));
 478   printf (" -c, --critical=seconds\n");
 479   printf ("    %s\n", _("Return critical if elapsed time exceeds value. Default off"));
 480
 481   printf (_(UT_TIMEOUT), DEFAULT_SOCKET_TIMEOUT);
 482
 483 #ifdef NP_EXTRA_OPTS
 484   printf ("\n");
 485   printf ("%s\n", _("Notes:"));
 486   printf (_(UT_EXTRA_OPTS_NOTES));
 487 #endif
 488
 489   printf (_(UT_SUPPORT));
 490 }
 491
 492
 493 void
 494 print_usage (void)
 495 {
 496   printf (_("Usage:"));
 497   printf ("%s -H host [-s server] [-a expected-address] [-A] [-t timeout] [-w warn] [-c crit]\n", progname);
 498 }