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