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 *****************************************************************************/
32 const char *progname = "check_dns";
33 const char *copyright = "2000-2008";
34 const char *email = "nagiosplug-devel@lists.sourceforge.net";
36 #include "common.h"
37 #include "utils.h"
38 #include "utils_base.h"
39 #include "netutils.h"
40 #include "runcmd.h"
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);
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;
56 int expect_authority = FALSE;
57 thresholds *time_thresholds = NULL;
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 }
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;
89 setlocale (LC_ALL, "");
90 bindtextdomain (PACKAGE, LOCALEDIR);
91 textdomain (PACKAGE);
93 /* Set signal handling and alarm */
94 if (signal (SIGALRM, popen_timeout_alarm_handler) == SIG_ERR) {
95 usage_va(_("Cannot catch SIGALRM"));
96 }
98 /* Parse extra opts if any */
99 argv=np_extra_opts (&argc, argv, progname);
101 if (process_arguments (argc, argv) == ERROR) {
102 usage_va(_("Could not parse arguments"));
103 }
105 /* get the command to run */
106 asprintf (&command_line, "%s %s %s", NSLOOKUP_COMMAND, query_address, dns_server);
108 alarm (timeout_interval);
109 gettimeofday (&tv, NULL);
111 if (verbose)
112 printf ("%s\n", command_line);
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 }
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));
127 if (verbose)
128 puts(chld_out.line[i]);
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 }
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++;
147 /* Strip leading spaces */
148 for (; *temp_buffer != '\0' && *temp_buffer == ' '; temp_buffer++)
149 /* NOOP */;
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 }
158 addresses[n_addresses++] = strdup(temp_buffer);
159 }
160 else if (strstr (chld_out.line[i], _("Non-authoritative answer:"))) {
161 non_authoritative = TRUE;
162 }
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 }
173 /* scan stderr */
174 for(i = 0; i < chld_err.lines; i++) {
175 if (verbose)
176 puts(chld_err.line[i]);
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 }
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);
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 asprintf(&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 asprintf(&msg, _("expected '%s' but got '%s'"), temp_buffer, address);
217 }
218 }
220 /* check if authoritative */
221 if (result == STATE_OK && expect_authority && non_authoritative) {
222 result = STATE_CRITICAL;
223 asprintf(&msg, _("server %s is not authoritative for %s"), dns_server, query_address);
224 }
226 microsec = deltime (tv);
227 elapsed_time = (double)microsec / 1.0e6;
229 if (result == STATE_OK) {
230 if (strchr (address, ',') == NULL)
231 multi_address = FALSE;
232 else
233 multi_address = TRUE;
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);
257 return result;
258 }
262 int
263 error_scan (char *input_buffer)
264 {
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;
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);
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);
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);
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);
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);
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);
302 /* Network is unreachable */
303 else if (strstr (input_buffer, "Network is unreachable"))
304 die (STATE_CRITICAL, _("Network is unreachable\n"));
306 /* Internal server failure */
307 else if (strstr (input_buffer, "Server failure"))
308 die (STATE_CRITICAL, _("DNS failure for %s\n"), dns_server);
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;
315 return STATE_OK;
317 }
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;
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 };
344 if (argc < 2)
345 return ERROR;
347 for (c = 1; c < argc; c++)
348 if (strcmp ("-to", argv[c]) == 0)
349 strcpy (argv[c], "-t");
351 while (1) {
352 c = getopt_long (argc, argv, "hVvAt:H:s:r:a:w:c:", long_opts, &opt_index);
354 if (c == -1 || c == EOF)
355 break;
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 }
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 }
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 }
426 set_thresholds(&time_thresholds, warning, critical);
428 return validate_arguments ();
429 }
432 int
433 validate_arguments ()
434 {
435 if (query_address[0] == 0)
436 return ERROR;
438 return OK;
439 }
442 void
443 print_help (void)
444 {
445 print_revision (progname, NP_VERSION);
447 printf ("Copyright (c) 1999 Ethan Galstad <nagios@nagios.org>\n");
448 printf (COPYRIGHT, copyright, email);
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."));
454 printf ("\n\n");
456 print_usage ();
458 printf (_(UT_HELP_VRSN));
459 printf (_(UT_EXTRA_OPTS));
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"));
477 printf (_(UT_TIMEOUT), DEFAULT_SOCKET_TIMEOUT);
479 #ifdef NP_EXTRA_OPTS
480 printf ("\n");
481 printf ("%s\n", _("Notes:"));
482 printf (_(UT_EXTRA_OPTS_NOTES));
483 #endif
485 printf (_(UT_SUPPORT));
486 }
489 void
490 print_usage (void)
491 {
492 printf (_("Usage:"));
493 printf ("%s -H host [-s server] [-a expected-address] [-A] [-t timeout] [-w warn] [-c crit]\n", progname);
494 }