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