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"
50 #include "netutils.h"
52 const char *progname = "check_dns";
53 const char *revision = "$Revision$";
54 const char *copyright = "2000-2003";
55 const char *email = "nagiosplug-devel@lists.sourceforge.net";
57 int process_arguments (int, char **);
58 int validate_arguments (void);
59 int error_scan (char *);
60 void print_help (void);
61 void print_usage (void);
63 #define ADDRESS_LENGTH 256
64 char query_address[ADDRESS_LENGTH] = "";
65 char dns_server[ADDRESS_LENGTH] = "";
66 char ptr_server[ADDRESS_LENGTH] = "";
67 int verbose = FALSE;
68 char expected_address[ADDRESS_LENGTH] = "";
69 int match_expected_address = FALSE;
71 int
72 main (int argc, char **argv)
73 {
74 char *command_line = NULL;
75 char input_buffer[MAX_INPUT_BUFFER];
76 char *output = NULL;
77 char *address = NULL;
78 char *temp_buffer = NULL;
79 int result = STATE_UNKNOWN;
80 double elapsed_time;
81 long microsec;
82 struct timeval tv;
83 int multi_address;
85 /* Set signal handling and alarm */
86 if (signal (SIGALRM, popen_timeout_alarm_handler) == SIG_ERR) {
87 printf (_("Cannot catch SIGALRM"));
88 return STATE_UNKNOWN;
89 }
91 if (process_arguments (argc, argv) != OK) {
92 print_usage ();
93 return STATE_UNKNOWN;
94 }
96 /* get the command to run */
97 asprintf (&command_line, "%s %s %s", NSLOOKUP_COMMAND, query_address, dns_server);
99 alarm (timeout_interval);
100 gettimeofday (&tv, NULL);
102 if (verbose)
103 printf ("%s\n", command_line);
104 /* run the command */
105 child_process = spopen (command_line);
106 if (child_process == NULL) {
107 printf (_("Could not open pipe: %s\n"), command_line);
108 return STATE_UNKNOWN;
109 }
111 child_stderr = fdopen (child_stderr_array[fileno (child_process)], "r");
112 if (child_stderr == NULL)
113 printf (_("Could not open stderr for %s\n"), command_line);
115 /* scan stdout */
116 while (fgets (input_buffer, MAX_INPUT_BUFFER - 1, child_process)) {
118 if (verbose)
119 printf ("%s\n", input_buffer);
121 if (strstr (input_buffer, ".in-addr.arpa")) {
122 if ((temp_buffer = strstr (input_buffer, "name = ")))
123 address = strdup (temp_buffer + 7);
124 else {
125 output = strdup (_("Unknown error (plugin)"));
126 result = STATE_WARNING;
127 }
128 }
130 /* the server is responding, we just got the host name... */
131 if (strstr (input_buffer, "Name:")) {
133 /* get the host address */
134 if (!fgets (input_buffer, MAX_INPUT_BUFFER - 1, child_process))
135 break;
137 if (verbose)
138 printf ("%s\n", input_buffer);
140 if ((temp_buffer = index (input_buffer, ':'))) {
141 temp_buffer++;
142 /* Strip leading spaces */
143 for (; *temp_buffer != '\0' && *temp_buffer == ' '; temp_buffer++)
144 /* NOOP */;
145 address = strdup (temp_buffer);
146 strip (address);
147 if (address==NULL || strlen(address)==0)
148 die (STATE_CRITICAL,
149 _("DNS CRITICAL - '%s' returned empty host name string\n"),
150 NSLOOKUP_COMMAND);
151 result = STATE_OK;
152 }
153 else {
154 output = strdup (_("Unknown error (plugin)"));
155 result = STATE_WARNING;
156 }
158 break;
159 }
161 result = error_scan (input_buffer);
162 if (result != STATE_OK) {
163 output = strdup (1 + index (input_buffer, ':'));
164 strip (output);
165 break;
166 }
168 }
170 /* scan stderr */
171 while (fgets (input_buffer, MAX_INPUT_BUFFER - 1, child_stderr)) {
172 if (error_scan (input_buffer) != STATE_OK) {
173 result = max_state (result, error_scan (input_buffer));
174 output = strdup (1 + index (input_buffer, ':'));
175 strip (output);
176 }
177 }
179 /* close stderr */
180 (void) fclose (child_stderr);
182 /* close stdout */
183 if (spclose (child_process)) {
184 result = max_state (result, STATE_WARNING);
185 if (!strcmp (output, ""))
186 output = strdup (_("nslookup returned error status"));
187 }
189 /* If we got here, we should have an address string,
190 and we can segfault if we do not */
191 if (address==NULL || strlen(address)==0)
192 die (STATE_CRITICAL,
193 _("DNS CRITICAL - '%s' output parsing exited with no address\n"),
194 NSLOOKUP_COMMAND);
196 /* compare to expected address */
197 if (result == STATE_OK && match_expected_address && strcmp(address, expected_address)) {
198 result = STATE_CRITICAL;
199 asprintf(&output, _("expected %s but got %s"), expected_address, address);
200 }
202 microsec = deltime (tv);
203 elapsed_time = (double)microsec / 1.0e6;
205 if (result == STATE_OK) {
206 if (strchr (address, ',') == NULL)
207 multi_address = FALSE;
208 else
209 multi_address = TRUE;
211 printf (_("DNS ok - %.3f seconds response time, address%s %s|time=%ldus\n"),
212 elapsed_time, (multi_address==TRUE ? "es are" : " is"), address, microsec);
213 }
214 else if (result == STATE_WARNING)
215 printf (_("DNS WARNING - %s\n"),
216 !strcmp (output, "") ? _(" Probably a non-existent host/domain") : output);
217 else if (result == STATE_CRITICAL)
218 printf (_("DNS CRITICAL - %s\n"),
219 !strcmp (output, "") ? _(" Probably a non-existent host/domain") : output);
220 else
221 printf (_("DNS problem - %s\n"),
222 !strcmp (output, "") ? _(" Probably a non-existent host/domain") : output);
224 return result;
225 }
227 int
228 error_scan (char *input_buffer)
229 {
231 /* the DNS lookup timed out */
232 if (strstr (input_buffer, "Note: nslookup is deprecated and may be removed from future releases.") ||
233 strstr (input_buffer, "Consider using the `dig' or `host' programs instead. Run nslookup with") ||
234 strstr (input_buffer, "the `-sil[ent]' option to prevent this message from appearing."))
235 return STATE_OK;
237 /* DNS server is not running... */
238 else if (strstr (input_buffer, "No response from server"))
239 die (STATE_CRITICAL, _("No response from name server %s\n"), dns_server);
241 /* Host name is valid, but server doesn't have records... */
242 else if (strstr (input_buffer, "No records"))
243 die (STATE_CRITICAL, _("Name server %s has no records\n"), dns_server);
245 /* Connection was refused */
246 else if (strstr (input_buffer, "Connection refused") ||
247 (strstr (input_buffer, "** server can't find") &&
248 strstr (input_buffer, ": REFUSED")) ||
249 (strstr (input_buffer, "Refused")))
250 die (STATE_CRITICAL, _("Connection to name server %s was refused\n"), dns_server);
252 /* Host or domain name does not exist */
253 else if (strstr (input_buffer, "Non-existent") ||
254 strstr (input_buffer, "** server can't find") ||
255 strstr (input_buffer,"NXDOMAIN"))
256 die (STATE_CRITICAL, _("Domain %s was not found by the server\n"), query_address);
258 /* Network is unreachable */
259 else if (strstr (input_buffer, "Network is unreachable"))
260 die (STATE_CRITICAL, _("Network is unreachable\n"));
262 /* Internal server failure */
263 else if (strstr (input_buffer, "Server failure"))
264 die (STATE_CRITICAL, _("Server failure for %s\n"), dns_server);
266 /* Request error or the DNS lookup timed out */
267 else if (strstr (input_buffer, "Format error") ||
268 strstr (input_buffer, "Timed out"))
269 return STATE_WARNING;
271 return STATE_OK;
273 }
275 /* process command-line arguments */
276 int
277 process_arguments (int argc, char **argv)
278 {
279 int c;
281 int opt_index = 0;
282 static struct option long_opts[] = {
283 {"help", no_argument, 0, 'h'},
284 {"version", no_argument, 0, 'V'},
285 {"verbose", no_argument, 0, 'v'},
286 {"timeout", required_argument, 0, 't'},
287 {"hostname", required_argument, 0, 'H'},
288 {"server", required_argument, 0, 's'},
289 {"reverse-server", required_argument, 0, 'r'},
290 {"expected-address", required_argument, 0, 'a'},
291 {0, 0, 0, 0}
292 };
294 if (argc < 2)
295 return ERROR;
297 for (c = 1; c < argc; c++)
298 if (strcmp ("-to", argv[c]) == 0)
299 strcpy (argv[c], "-t");
301 while (1) {
302 c = getopt_long (argc, argv, "hVvt:H:s:r:a:", long_opts, &opt_index);
304 if (c == -1 || c == EOF)
305 break;
307 switch (c) {
308 case '?': /* args not parsable */
309 printf (_("%s: Unknown argument: %s\n\n"), progname, optarg);
310 print_usage ();
311 exit (STATE_UNKNOWN);
312 case 'h': /* help */
313 print_help ();
314 exit (STATE_OK);
315 case 'V': /* version */
316 print_revision (progname, revision);
317 exit (STATE_OK);
318 case 'v': /* version */
319 verbose = TRUE;
320 break;
321 case 't': /* timeout period */
322 timeout_interval = atoi (optarg);
323 break;
324 case 'H': /* hostname */
325 if (strlen (optarg) >= ADDRESS_LENGTH)
326 die (STATE_UNKNOWN, _("Input buffer overflow\n"));
327 strcpy (query_address, optarg);
328 break;
329 case 's': /* server name */
330 /* TODO: this is_host check is probably unnecessary. Better to confirm nslookup
331 response matches */
332 if (is_host (optarg) == FALSE) {
333 printf (_("Invalid server name/address\n\n"));
334 print_usage ();
335 exit (STATE_UNKNOWN);
336 }
337 if (strlen (optarg) >= ADDRESS_LENGTH)
338 die (STATE_UNKNOWN, _("Input buffer overflow\n"));
339 strcpy (dns_server, optarg);
340 break;
341 case 'r': /* reverse server name */
342 /* TODO: Is this is_host necessary? */
343 if (is_host (optarg) == FALSE) {
344 printf (_("Invalid host name/address\n\n"));
345 print_usage ();
346 exit (STATE_UNKNOWN);
347 }
348 if (strlen (optarg) >= ADDRESS_LENGTH)
349 die (STATE_UNKNOWN, _("Input buffer overflow\n"));
350 strcpy (ptr_server, optarg);
351 break;
352 case 'a': /* expected address */
353 if (strlen (optarg) >= ADDRESS_LENGTH)
354 die (STATE_UNKNOWN, _("Input buffer overflow\n"));
355 strcpy (expected_address, optarg);
356 match_expected_address = TRUE;
357 break;
358 }
359 }
361 c = optind;
362 if (strlen(query_address)==0 && c<argc) {
363 if (strlen(argv[c])>=ADDRESS_LENGTH)
364 die (STATE_UNKNOWN, _("Input buffer overflow\n"));
365 strcpy (query_address, argv[c++]);
366 }
368 if (strlen(dns_server)==0 && c<argc) {
369 /* TODO: See -s option */
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 die (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 }
395 \f
396 void
397 print_help (void)
398 {
399 print_revision (progname, revision);
401 printf (_(COPYRIGHT), copyright, email);
403 print_usage ();
405 printf (_(UT_HELP_VRSN));
407 printf (_("\
408 -H, --hostname=HOST\n\
409 The name or address you want to query\n\
410 -s, --server=HOST\n\
411 Optional DNS server you want to use for the lookup\n\
412 -a, --expected-address=IP-ADDRESS\n\
413 Optional IP address you expect the DNS server to return\n"));
415 printf (_(UT_TIMEOUT), DEFAULT_SOCKET_TIMEOUT);
417 printf (_("\n\
418 This plugin uses the nslookup program to obtain the IP address\n\
419 for the given host/domain query. A optional DNS server to use may\n\
420 be specified. If no DNS server is specified, the default server(s)\n\
421 specified in /etc/resolv.conf will be used.\n"));
423 printf (_(UT_SUPPORT));
424 }
429 void
430 print_usage (void)
431 {
432 printf (_("\
433 Usage: %s -H host [-s server] [-a expected-address] [-t timeout]\n\
434 %s --help\n\
435 %s --version\n"),
436 progname, progname, progname);
437 }