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;
78 double elapsed_time;
79 struct timeval tv;
80 int multi_address;
82 /* Set signal handling and alarm */
83 if (signal (SIGALRM, popen_timeout_alarm_handler) == SIG_ERR) {
84 printf ("Cannot catch SIGALRM");
85 return STATE_UNKNOWN;
86 }
88 if (process_arguments (argc, argv) != OK) {
89 print_usage ();
90 return STATE_UNKNOWN;
91 }
93 /* get the command to run */
94 asprintf (&command_line, "%s %s %s", NSLOOKUP_COMMAND, query_address, dns_server);
96 alarm (timeout_interval);
97 gettimeofday (&tv, NULL);
99 if (verbose)
100 printf ("%s\n", command_line);
101 /* run the command */
102 child_process = spopen (command_line);
103 if (child_process == NULL) {
104 printf ("Could not open pipe: %s\n", command_line);
105 return STATE_UNKNOWN;
106 }
108 child_stderr = fdopen (child_stderr_array[fileno (child_process)], "r");
109 if (child_stderr == NULL)
110 printf ("Could not open stderr for %s\n", command_line);
112 /* scan stdout */
113 while (fgets (input_buffer, MAX_INPUT_BUFFER - 1, child_process)) {
115 if (verbose)
116 printf ("%s\n", input_buffer);
118 if (strstr (input_buffer, ".in-addr.arpa")) {
119 if ((temp_buffer = strstr (input_buffer, "name = ")))
120 address = strscpy (address, temp_buffer + 7);
121 else {
122 output = strscpy (output, "Unknown error (plugin)");
123 result = STATE_WARNING;
124 }
125 }
127 /* the server is responding, we just got the host name... */
128 if (strstr (input_buffer, "Name:")) {
130 /* get the host address */
131 if (!fgets (input_buffer, MAX_INPUT_BUFFER - 1, child_process))
132 break;
134 if (verbose)
135 printf ("%s\n", input_buffer);
137 if ((temp_buffer = index (input_buffer, ':'))) {
138 temp_buffer++;
139 /* Strip leading spaces */
140 for (; *temp_buffer != '\0' && *temp_buffer == ' '; temp_buffer++)
141 /* NOOP */;
142 address = strdup (temp_buffer);
143 strip (address);
144 if (address==NULL || strlen(address)==0)
145 terminate (STATE_CRITICAL,
146 "DNS CRITICAL - '%s' returned empty host name string\n",
147 NSLOOKUP_COMMAND);
148 result = STATE_OK;
149 }
150 else {
151 output = strdup ("Unknown error (plugin)");
152 result = STATE_WARNING;
153 }
155 break;
156 }
158 result = error_scan (input_buffer);
159 if (result != STATE_OK) {
160 output = strscpy (output, 1 + index (input_buffer, ':'));
161 strip (output);
162 break;
163 }
165 }
167 /* scan stderr */
168 while (fgets (input_buffer, MAX_INPUT_BUFFER - 1, child_stderr)) {
169 if (error_scan (input_buffer) != STATE_OK) {
170 result = max_state (result, error_scan (input_buffer));
171 output = strscpy (output, 1 + index (input_buffer, ':'));
172 strip (output);
173 }
174 }
176 /* close stderr */
177 (void) fclose (child_stderr);
179 /* close stdout */
180 if (spclose (child_process)) {
181 result = max_state (result, STATE_WARNING);
182 if (!strcmp (output, ""))
183 output = strscpy (output, "nslookup returned error status");
184 }
186 /* If we got here, we should have an address string,
187 and we can segfault if we do not */
188 if (address==NULL || strlen(address)==0)
189 terminate (STATE_CRITICAL,
190 "DNS CRITICAL - '%s' output parsing exited with no address\n",
191 NSLOOKUP_COMMAND);
193 /* compare to expected address */
194 if (result == STATE_OK && match_expected_address && strcmp(address, expected_address)) {
195 result = STATE_CRITICAL;
196 asprintf(&output, "expected %s but got %s", expected_address, address);
197 }
199 elapsed_time = delta_time (tv);
201 if (result == STATE_OK) {
202 if (strchr (address, ',') == NULL)
203 multi_address = FALSE;
204 else
205 multi_address = TRUE;
207 printf ("DNS ok - %.3f seconds response time, address%s %s|time=%.3f\n",
208 elapsed_time, (multi_address==TRUE ? "es are" : " is"), address, elapsed_time);
209 }
210 else if (result == STATE_WARNING)
211 printf ("DNS WARNING - %s\n",
212 !strcmp (output, "") ? " Probably a non-existent host/domain" : output);
213 else if (result == STATE_CRITICAL)
214 printf ("DNS CRITICAL - %s\n",
215 !strcmp (output, "") ? " Probably a non-existent host/domain" : output);
216 else
217 printf ("DNS problem - %s\n",
218 !strcmp (output, "") ? " Probably a non-existent host/domain" : output);
220 return result;
221 }
223 int
224 error_scan (char *input_buffer)
225 {
227 /* the DNS lookup timed out */
228 if (strstr (input_buffer,
229 "Note: nslookup is deprecated and may be removed from future releases.")
230 || strstr (input_buffer,
231 "Consider using the `dig' or `host' programs instead. Run nslookup with")
232 || strstr (input_buffer,
233 "the `-sil[ent]' option to prevent this message from appearing."))
234 return STATE_OK;
236 /* the DNS lookup timed out */
237 else if (strstr (input_buffer, "Timed out"))
238 return STATE_WARNING;
240 /* DNS server is not running... */
241 else if (strstr (input_buffer, "No response from server"))
242 return STATE_CRITICAL;
244 /* Host name is valid, but server doesn't have records... */
245 else if (strstr (input_buffer, "No records"))
246 return STATE_WARNING;
248 /* Host or domain name does not exist */
249 else if (strstr (input_buffer, "Non-existent"))
250 return STATE_CRITICAL;
251 else if (strstr (input_buffer, "** server can't find"))
252 return STATE_CRITICAL;
253 else if(strstr(input_buffer,"NXDOMAIN")) /* 9.x */
254 return STATE_CRITICAL;
256 /* Connection was refused */
257 else if (strstr (input_buffer, "Connection refused"))
258 return STATE_CRITICAL;
260 /* Network is unreachable */
261 else if (strstr (input_buffer, "Network is unreachable"))
262 return STATE_CRITICAL;
264 /* Internal server failure */
265 else if (strstr (input_buffer, "Server failure"))
266 return STATE_CRITICAL;
268 /* DNS server refused to service request */
269 else if (strstr (input_buffer, "Refused"))
270 return STATE_CRITICAL;
272 /* Request error */
273 else if (strstr (input_buffer, "Format error"))
274 return STATE_WARNING;
276 else
277 return STATE_OK;
279 }
281 /* process command-line arguments */
282 int
283 process_arguments (int argc, char **argv)
284 {
285 int c;
287 int opt_index = 0;
288 static struct option long_opts[] = {
289 {"help", no_argument, 0, 'h'},
290 {"version", no_argument, 0, 'V'},
291 {"verbose", no_argument, 0, 'v'},
292 {"timeout", required_argument, 0, 't'},
293 {"hostname", required_argument, 0, 'H'},
294 {"server", required_argument, 0, 's'},
295 {"reverse-server", required_argument, 0, 'r'},
296 {"expected-address", required_argument, 0, 'a'},
297 {0, 0, 0, 0}
298 };
300 if (argc < 2)
301 return ERROR;
303 for (c = 1; c < argc; c++)
304 if (strcmp ("-to", argv[c]) == 0)
305 strcpy (argv[c], "-t");
307 while (1) {
308 c = getopt_long (argc, argv, "hVvt:H:s:r:a:", long_opts, &opt_index);
310 if (c == -1 || c == EOF)
311 break;
313 switch (c) {
314 case '?': /* args not parsable */
315 printf ("%s: Unknown argument: %s\n\n", progname, optarg);
316 print_usage ();
317 exit (STATE_UNKNOWN);
318 case 'h': /* help */
319 print_help ();
320 exit (STATE_OK);
321 case 'V': /* version */
322 print_revision (progname, REVISION);
323 exit (STATE_OK);
324 case 'v': /* version */
325 verbose = TRUE;
326 break;
327 case 't': /* timeout period */
328 timeout_interval = atoi (optarg);
329 break;
330 case 'H': /* hostname */
331 if (strlen (optarg) >= ADDRESS_LENGTH)
332 terminate (STATE_UNKNOWN, "Input buffer overflow\n");
333 strcpy (query_address, optarg);
334 break;
335 case 's': /* server name */
336 /* TODO: this is_host check is probably unnecessary. Better to confirm nslookup
337 response matches */
338 if (is_host (optarg) == FALSE) {
339 printf ("Invalid server name/address\n\n");
340 print_usage ();
341 exit (STATE_UNKNOWN);
342 }
343 if (strlen (optarg) >= ADDRESS_LENGTH)
344 terminate (STATE_UNKNOWN, "Input buffer overflow\n");
345 strcpy (dns_server, optarg);
346 break;
347 case 'r': /* reverse server name */
348 /* TODO: Is this is_host necessary? */
349 if (is_host (optarg) == FALSE) {
350 printf ("Invalid host name/address\n\n");
351 print_usage ();
352 exit (STATE_UNKNOWN);
353 }
354 if (strlen (optarg) >= ADDRESS_LENGTH)
355 terminate (STATE_UNKNOWN, "Input buffer overflow\n");
356 strcpy (ptr_server, optarg);
357 break;
358 case 'a': /* expected address */
359 if (strlen (optarg) >= ADDRESS_LENGTH)
360 terminate (STATE_UNKNOWN, "Input buffer overflow\n");
361 strcpy (expected_address, optarg);
362 match_expected_address = TRUE;
363 break;
364 }
365 }
367 c = optind;
368 if (strlen(query_address)==0 && c<argc) {
369 if (strlen(argv[c])>=ADDRESS_LENGTH)
370 terminate (STATE_UNKNOWN, "Input buffer overflow\n");
371 strcpy (query_address, argv[c++]);
372 }
374 if (strlen(dns_server)==0 && c<argc) {
375 /* TODO: See -s option */
376 if (is_host(argv[c]) == FALSE) {
377 printf ("Invalid name/address: %s\n\n", argv[c]);
378 return ERROR;
379 }
380 if (strlen(argv[c]) >= ADDRESS_LENGTH)
381 terminate (STATE_UNKNOWN, "Input buffer overflow\n");
382 strcpy (dns_server, argv[c++]);
383 }
385 return validate_arguments ();
386 }
388 int
389 validate_arguments ()
390 {
391 if (query_address[0] == 0)
392 return ERROR;
393 else
394 return OK;
395 }
397 void
398 print_usage (void)
399 {
400 printf ("Usage: %s -H host [-s server] [-a expected-address] [-t timeout]\n" " %s --help\n"
401 " %s --version\n", progname, progname, progname);
402 }
404 void
405 print_help (void)
406 {
407 print_revision (progname, REVISION);
408 printf ("Copyright (c) 1999 Ethan Galstad (nagios@nagios.org)\n\n");
409 print_usage ();
410 printf
411 ("\nOptions:\n"
412 "-H, --hostname=HOST\n"
413 " The name or address you want to query\n"
414 "-s, --server=HOST\n"
415 " Optional DNS server you want to use for the lookup\n"
416 "-a, --expected-address=IP-ADDRESS\n"
417 " Optional IP address you expect the DNS server to return\n"
418 "-t, --timeout=INTEGER\n"
419 " Seconds before connection times out (default: %d)\n"
420 "-h, --help\n"
421 " Print detailed help\n"
422 "-V, --version\n"
423 " Print version numbers and license information\n"
424 "\n"
425 "This plugin uses the nslookup program to obtain the IP address\n"
426 "for the given host/domain query. A optional DNS server to use may\n"
427 "be specified. If no DNS server is specified, the default server(s)\n"
428 "specified in /etc/resolv.conf will be used.\n", DEFAULT_SOCKET_TIMEOUT);
429 }