1 /******************************************************************************
2 *
3 * CHECK_DNS.C
4 *
5 * Program: DNS plugin for Nagios
6 * License: GPL
7 * Copyright (c) 1999 Ethan Galstad (nagios@nagios.org)
8 *
9 * Last Modified: $Date$
10 *
11 * Notes:
12 * - Safe popen added by Karl DeBisschop 9-11-99
13 * - expected-address parameter added by Alex Chaffee - 7 Oct 2002
14 *
15 * Command line: (see print_usage)
16 *
17 * Description:
18 *
19 * This program will use the nslookup program to obtain the IP address
20 * for a given host name. A optional DNS server may be specified. If
21 * no DNS server is specified, the default server(s) for the system
22 * are used.
23 *
24 * Return Values:
25 * OK The DNS query was successful (host IP address was returned).
26 * WARNING The DNS server responded, but could not fulfill the request.
27 * CRITICAL The DNS server is not responding or encountered an error.
28 *
29 * License Information:
30 *
31 * This program is free software; you can redistribute it and/or modify
32 * it under the terms of the GNU General Public License as published by
33 * the Free Software Foundation; either version 2 of the License, or
34 * (at your option) any later version.
35 *
36 * This program is distributed in the hope that it will be useful,
37 * but WITHOUT ANY WARRANTY; without even the implied warranty of
38 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
39 * GNU General Public License for more details.
40 *
41 * You should have received a copy of the GNU General Public License
42 * along with this program; if not, write to the Free Software
43 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
44 *
45 *****************************************************************************/
47 #include "common.h"
48 #include "popen.h"
49 #include "utils.h"
51 const char *progname = "check_dns";
52 #define REVISION "$Revision$"
53 #define COPYRIGHT "2000-2002"
55 int process_arguments (int, char **);
56 int validate_arguments (void);
57 void print_usage (void);
58 void print_help (void);
59 int error_scan (char *);
61 #define ADDRESS_LENGTH 256
62 char query_address[ADDRESS_LENGTH] = "";
63 char dns_server[ADDRESS_LENGTH] = "";
64 char ptr_server[ADDRESS_LENGTH] = "";
65 int verbose = FALSE;
66 char expected_address[ADDRESS_LENGTH] = "";
67 int match_expected_address = FALSE;
69 int
70 main (int argc, char **argv)
71 {
72 char *command_line = NULL;
73 char input_buffer[MAX_INPUT_BUFFER];
74 char *output = NULL;
75 char *address = NULL;
76 char *temp_buffer = NULL;
77 int result = STATE_UNKNOWN;
79 /* Set signal handling and alarm */
80 if (signal (SIGALRM, popen_timeout_alarm_handler) == SIG_ERR) {
81 printf ("Cannot catch SIGALRM");
82 return STATE_UNKNOWN;
83 }
85 if (process_arguments (argc, argv) != OK) {
86 print_usage ();
87 return STATE_UNKNOWN;
88 }
90 /* get the command to run */
91 asprintf (&command_line, "%s %s %s", NSLOOKUP_COMMAND, query_address, dns_server);
93 alarm (timeout_interval);
94 time (&start_time);
96 if (verbose)
97 printf ("%s\n", command_line);
98 /* run the command */
99 child_process = spopen (command_line);
100 if (child_process == NULL) {
101 printf ("Could not open pipe: %s\n", command_line);
102 return STATE_UNKNOWN;
103 }
105 child_stderr = fdopen (child_stderr_array[fileno (child_process)], "r");
106 if (child_stderr == NULL)
107 printf ("Could not open stderr for %s\n", command_line);
109 /* scan stdout */
110 while (fgets (input_buffer, MAX_INPUT_BUFFER - 1, child_process)) {
112 if (verbose)
113 printf ("%s\n", input_buffer);
115 if (strstr (input_buffer, ".in-addr.arpa")) {
116 if ((temp_buffer = strstr (input_buffer, "name = ")))
117 address = strscpy (address, temp_buffer + 7);
118 else {
119 output = strscpy (output, "Unknown error (plugin)");
120 result = STATE_WARNING;
121 }
122 }
124 /* the server is responding, we just got the host name... */
125 if (strstr (input_buffer, "Name:")) {
127 /* get the host address */
128 if (!fgets (input_buffer, MAX_INPUT_BUFFER - 1, child_process))
129 break;
131 if (verbose)
132 printf ("%s\n", input_buffer);
134 if ((temp_buffer = index (input_buffer, ':'))) {
135 temp_buffer++;
136 /* Strip leading spaces */
137 for (; *temp_buffer != '\0' && *temp_buffer == ' '; temp_buffer++)
138 /* NOOP */;
139 address = strscpy (address, temp_buffer);
140 strip (address);
141 result = STATE_OK;
142 }
143 else {
144 output = strscpy (output, "Unknown error (plugin)");
145 result = STATE_WARNING;
146 }
148 break;
149 }
151 result = error_scan (input_buffer);
152 if (result != STATE_OK) {
153 output = strscpy (output, 1 + index (input_buffer, ':'));
154 break;
155 }
157 }
159 /* scan stderr */
160 while (fgets (input_buffer, MAX_INPUT_BUFFER - 1, child_stderr)) {
161 if (error_scan (input_buffer) != STATE_OK) {
162 result = max_state (result, error_scan (input_buffer));
163 output = strscpy (output, 1 + index (input_buffer, ':'));
164 }
165 }
167 /* close stderr */
168 (void) fclose (child_stderr);
170 /* close stdout */
171 if (spclose (child_process)) {
172 result = max_state (result, STATE_WARNING);
173 if (!strcmp (output, ""))
174 output = strscpy (output, "nslookup returned error status");
175 }
177 /* compare to expected address */
178 if (result == STATE_OK && match_expected_address && strcmp(address, expected_address)) {
179 result = STATE_CRITICAL;
180 asprintf(&output, "expected %s but got %s", expected_address, address);
181 }
183 (void) time (&end_time);
185 if (result == STATE_OK)
186 printf ("DNS ok - %d seconds response time, Address(es) is/are %s\n",
187 (int) (end_time - start_time), address);
188 else if (result == STATE_WARNING)
189 printf ("DNS WARNING - %s\n",
190 !strcmp (output, "") ? " Probably a non-existent host/domain" : output);
191 else if (result == STATE_CRITICAL)
192 printf ("DNS CRITICAL - %s\n",
193 !strcmp (output, "") ? " Probably a non-existent host/domain" : output);
194 else
195 printf ("DNS problem - %s\n",
196 !strcmp (output, "") ? " Probably a non-existent host/domain" : output);
198 return result;
199 }
201 int
202 error_scan (char *input_buffer)
203 {
205 /* the DNS lookup timed out */
206 if (strstr (input_buffer,
207 "Note: nslookup is deprecated and may be removed from future releases.")
208 || strstr (input_buffer,
209 "Consider using the `dig' or `host' programs instead. Run nslookup with")
210 || strstr (input_buffer,
211 "the `-sil[ent]' option to prevent this message from appearing."))
212 return STATE_OK;
214 /* the DNS lookup timed out */
215 else if (strstr (input_buffer, "Timed out"))
216 return STATE_WARNING;
218 /* DNS server is not running... */
219 else if (strstr (input_buffer, "No response from server"))
220 return STATE_CRITICAL;
222 /* Host name is valid, but server doesn't have records... */
223 else if (strstr (input_buffer, "No records"))
224 return STATE_WARNING;
226 /* Host or domain name does not exist */
227 else if (strstr (input_buffer, "Non-existent"))
228 return STATE_CRITICAL;
229 else if (strstr (input_buffer, "** server can't find"))
230 return STATE_CRITICAL;
231 else if(strstr(input_buffer,"NXDOMAIN")) /* 9.x */
232 return STATE_CRITICAL;
234 /* Connection was refused */
235 else if (strstr (input_buffer, "Connection refused"))
236 return STATE_CRITICAL;
238 /* Network is unreachable */
239 else if (strstr (input_buffer, "Network is unreachable"))
240 return STATE_CRITICAL;
242 /* Internal server failure */
243 else if (strstr (input_buffer, "Server failure"))
244 return STATE_CRITICAL;
246 /* DNS server refused to service request */
247 else if (strstr (input_buffer, "Refused"))
248 return STATE_CRITICAL;
250 /* Request error */
251 else if (strstr (input_buffer, "Format error"))
252 return STATE_WARNING;
254 else
255 return STATE_OK;
257 }
259 /* process command-line arguments */
260 int
261 process_arguments (int argc, char **argv)
262 {
263 int c;
265 #ifdef HAVE_GETOPT_H
266 int opt_index = 0;
267 static struct option long_opts[] = {
268 {"help", no_argument, 0, 'h'},
269 {"version", no_argument, 0, 'V'},
270 {"verbose", no_argument, 0, 'v'},
271 {"timeout", required_argument, 0, 't'},
272 {"hostname", required_argument, 0, 'H'},
273 {"server", required_argument, 0, 's'},
274 {"reverse-server", required_argument, 0, 'r'},
275 {"expected-address", required_argument, 0, 'a'},
276 {0, 0, 0, 0}
277 };
278 #endif
280 if (argc < 2)
281 return ERROR;
283 for (c = 1; c < argc; c++)
284 if (strcmp ("-to", argv[c]) == 0)
285 strcpy (argv[c], "-t");
287 while (1) {
288 #ifdef HAVE_GETOPT_H
289 c = getopt_long (argc, argv, "hVvt:H:s:r:a:", long_opts, &opt_index);
290 #else
291 c = getopt (argc, argv, "hVvt:H:s:r:a:");
292 #endif
294 if (c == -1 || c == EOF)
295 break;
297 switch (c) {
298 case '?': /* args not parsable */
299 printf ("%s: Unknown argument: %s\n\n", progname, optarg);
300 print_usage ();
301 exit (STATE_UNKNOWN);
302 case 'h': /* help */
303 print_help ();
304 exit (STATE_OK);
305 case 'V': /* version */
306 print_revision (progname, REVISION);
307 exit (STATE_OK);
308 case 'v': /* version */
309 verbose = TRUE;
310 break;
311 case 't': /* timeout period */
312 timeout_interval = atoi (optarg);
313 break;
314 case 'H': /* hostname */
315 if (is_host (optarg) == FALSE) {
316 printf ("Invalid host name/address\n\n");
317 print_usage ();
318 exit (STATE_UNKNOWN);
319 }
320 if (strlen (optarg) >= ADDRESS_LENGTH)
321 terminate (STATE_UNKNOWN, "Input buffer overflow\n");
322 strcpy (query_address, optarg);
323 break;
324 case 's': /* server name */
325 if (is_host (optarg) == FALSE) {
326 printf ("Invalid server name/address\n\n");
327 print_usage ();
328 exit (STATE_UNKNOWN);
329 }
330 if (strlen (optarg) >= ADDRESS_LENGTH)
331 terminate (STATE_UNKNOWN, "Input buffer overflow\n");
332 strcpy (dns_server, optarg);
333 break;
334 case 'r': /* reverse server name */
335 if (is_host (optarg) == FALSE) {
336 printf ("Invalid host name/address\n\n");
337 print_usage ();
338 exit (STATE_UNKNOWN);
339 }
340 if (strlen (optarg) >= ADDRESS_LENGTH)
341 terminate (STATE_UNKNOWN, "Input buffer overflow\n");
342 strcpy (ptr_server, optarg);
343 break;
344 case 'a': /* expected address */
345 if (is_dotted_quad (optarg) == FALSE) {
346 printf ("Invalid expected address\n\n");
347 print_usage ();
348 exit (STATE_UNKNOWN);
349 }
350 if (strlen (optarg) >= ADDRESS_LENGTH)
351 terminate (STATE_UNKNOWN, "Input buffer overflow\n");
352 strcpy (expected_address, optarg);
353 match_expected_address = TRUE;
354 break;
355 }
356 }
358 c = optind;
359 if (strlen(query_address)==0 && c<argc) {
360 if (is_host(argv[c])==FALSE) {
361 printf ("Invalid name/address: %s\n\n", argv[c]);
362 return ERROR;
363 }
364 if (strlen(argv[c])>=ADDRESS_LENGTH)
365 terminate (STATE_UNKNOWN, "Input buffer overflow\n");
366 strcpy (query_address, argv[c++]);
367 }
369 if (strlen(dns_server)==0 && c<argc) {
370 if (is_host(argv[c]) == FALSE) {
371 printf ("Invalid name/address: %s\n\n", argv[c]);
372 return ERROR;
373 }
374 if (strlen(argv[c]) >= ADDRESS_LENGTH)
375 terminate (STATE_UNKNOWN, "Input buffer overflow\n");
376 strcpy (dns_server, argv[c++]);
377 }
379 return validate_arguments ();
380 }
382 int
383 validate_arguments ()
384 {
385 if (query_address[0] == 0)
386 return ERROR;
387 else
388 return OK;
389 }
391 void
392 print_usage (void)
393 {
394 printf ("Usage: %s -H host [-s server] [-a expected-address] [-t timeout]\n" " %s --help\n"
395 " %s --version\n", progname, progname, progname);
396 }
398 void
399 print_help (void)
400 {
401 print_revision (progname, REVISION);
402 printf ("Copyright (c) 1999 Ethan Galstad (nagios@nagios.org)\n\n");
403 print_usage ();
404 printf
405 ("\nOptions:\n"
406 "-H, --hostname=HOST\n"
407 " The name or address you want to query\n"
408 "-s, --server=HOST\n"
409 " Optional DNS server you want to use for the lookup\n"
410 "-a, --expected-address=IP-ADDRESS\n"
411 " Optional IP address you expect the DNS server to return\n"
412 "-t, --timeout=INTEGER\n"
413 " Seconds before connection times out (default: %d)\n"
414 "-h, --help\n"
415 " Print detailed help\n"
416 "-V, --version\n"
417 " Print version numbers and license information\n"
418 "\n"
419 "This plugin uses the nslookup program to obtain the IP address\n"
420 "for the given host/domain query. A optional DNS server to use may\n"
421 "be specified. If no DNS server is specified, the default server(s)\n"
422 "specified in /etc/resolv.conf will be used.\n", DEFAULT_SOCKET_TIMEOUT);
423 }