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|
/******************************************************************************
*
* CHECK_DNS.C
*
* Program: DNS plugin for Nagios
* License: GPL
* Copyright (c) 1999 Ethan Galstad (nagios@nagios.org)
*
* Last Modified: $Date$
*
* Notes:
* - Safe popen added by Karl DeBisschop 9-11-99
* - expected-address parameter added by Alex Chaffee - 7 Oct 2002
*
* Command line: (see print_usage)
*
* Description:
*
* This program will use the nslookup program to obtain the IP address
* for a given host name. A optional DNS server may be specified. If
* no DNS server is specified, the default server(s) for the system
* are used.
*
* Return Values:
* OK The DNS query was successful (host IP address was returned).
* WARNING The DNS server responded, but could not fulfill the request.
* CRITICAL The DNS server is not responding or encountered an error.
*
* License Information:
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
*****************************************************************************/
#include "common.h"
#include "popen.h"
#include "utils.h"
const char *progname = "check_dns";
#define REVISION "$Revision$"
#define COPYRIGHT "2000-2002"
int process_arguments (int, char **);
int validate_arguments (void);
void print_usage (void);
void print_help (void);
int error_scan (char *);
#define ADDRESS_LENGTH 256
char query_address[ADDRESS_LENGTH] = "";
char dns_server[ADDRESS_LENGTH] = "";
char ptr_server[ADDRESS_LENGTH] = "";
int verbose = FALSE;
char expected_address[ADDRESS_LENGTH] = "";
int match_expected_address = FALSE;
int
main (int argc, char **argv)
{
char *command_line = NULL;
char input_buffer[MAX_INPUT_BUFFER];
char *output = NULL;
char *address = NULL;
char *temp_buffer = NULL;
int result = STATE_UNKNOWN;
double elapsed_time;
struct timeval tv;
int multi_address;
/* Set signal handling and alarm */
if (signal (SIGALRM, popen_timeout_alarm_handler) == SIG_ERR) {
printf ("Cannot catch SIGALRM");
return STATE_UNKNOWN;
}
if (process_arguments (argc, argv) != OK) {
print_usage ();
return STATE_UNKNOWN;
}
/* get the command to run */
asprintf (&command_line, "%s %s %s", NSLOOKUP_COMMAND, query_address, dns_server);
alarm (timeout_interval);
gettimeofday (&tv, NULL);
if (verbose)
printf ("%s\n", command_line);
/* run the command */
child_process = spopen (command_line);
if (child_process == NULL) {
printf ("Could not open pipe: %s\n", command_line);
return STATE_UNKNOWN;
}
child_stderr = fdopen (child_stderr_array[fileno (child_process)], "r");
if (child_stderr == NULL)
printf ("Could not open stderr for %s\n", command_line);
/* scan stdout */
while (fgets (input_buffer, MAX_INPUT_BUFFER - 1, child_process)) {
if (verbose)
printf ("%s\n", input_buffer);
if (strstr (input_buffer, ".in-addr.arpa")) {
if ((temp_buffer = strstr (input_buffer, "name = ")))
address = strscpy (address, temp_buffer + 7);
else {
output = strscpy (output, "Unknown error (plugin)");
result = STATE_WARNING;
}
}
/* the server is responding, we just got the host name... */
if (strstr (input_buffer, "Name:")) {
/* get the host address */
if (!fgets (input_buffer, MAX_INPUT_BUFFER - 1, child_process))
break;
if (verbose)
printf ("%s\n", input_buffer);
if ((temp_buffer = index (input_buffer, ':'))) {
temp_buffer++;
/* Strip leading spaces */
for (; *temp_buffer != '\0' && *temp_buffer == ' '; temp_buffer++)
/* NOOP */;
address = strscpy (address, temp_buffer);
strip (address);
result = STATE_OK;
}
else {
output = strscpy (output, "Unknown error (plugin)");
result = STATE_WARNING;
}
break;
}
result = error_scan (input_buffer);
if (result != STATE_OK) {
output = strscpy (output, 1 + index (input_buffer, ':'));
break;
}
}
/* scan stderr */
while (fgets (input_buffer, MAX_INPUT_BUFFER - 1, child_stderr)) {
if (error_scan (input_buffer) != STATE_OK) {
result = max_state (result, error_scan (input_buffer));
output = strscpy (output, 1 + index (input_buffer, ':'));
}
}
/* close stderr */
(void) fclose (child_stderr);
/* close stdout */
if (spclose (child_process)) {
result = max_state (result, STATE_WARNING);
if (!strcmp (output, ""))
output = strscpy (output, "nslookup returned error status");
}
/* compare to expected address */
if (result == STATE_OK && match_expected_address && strcmp(address, expected_address)) {
result = STATE_CRITICAL;
asprintf(&output, "expected %s but got %s", expected_address, address);
}
elapsed_time = delta_time (tv);
if (result == STATE_OK) {
if (strchr (address, ',') == NULL)
multi_address = FALSE;
else
multi_address = TRUE;
printf ("DNS ok - %-7.3f seconds response time, address%s %s|time=%-7.3f\n",
elapsed_time, (multi_address==TRUE ? "es are" : " is"), address, elapsed_time);
}
else if (result == STATE_WARNING)
printf ("DNS WARNING - %s\n",
!strcmp (output, "") ? " Probably a non-existent host/domain" : output);
else if (result == STATE_CRITICAL)
printf ("DNS CRITICAL - %s\n",
!strcmp (output, "") ? " Probably a non-existent host/domain" : output);
else
printf ("DNS problem - %s\n",
!strcmp (output, "") ? " Probably a non-existent host/domain" : output);
return result;
}
int
error_scan (char *input_buffer)
{
/* the DNS lookup timed out */
if (strstr (input_buffer,
"Note: nslookup is deprecated and may be removed from future releases.")
|| strstr (input_buffer,
"Consider using the `dig' or `host' programs instead. Run nslookup with")
|| strstr (input_buffer,
"the `-sil[ent]' option to prevent this message from appearing."))
return STATE_OK;
/* the DNS lookup timed out */
else if (strstr (input_buffer, "Timed out"))
return STATE_WARNING;
/* DNS server is not running... */
else if (strstr (input_buffer, "No response from server"))
return STATE_CRITICAL;
/* Host name is valid, but server doesn't have records... */
else if (strstr (input_buffer, "No records"))
return STATE_WARNING;
/* Host or domain name does not exist */
else if (strstr (input_buffer, "Non-existent"))
return STATE_CRITICAL;
else if (strstr (input_buffer, "** server can't find"))
return STATE_CRITICAL;
else if(strstr(input_buffer,"NXDOMAIN")) /* 9.x */
return STATE_CRITICAL;
/* Connection was refused */
else if (strstr (input_buffer, "Connection refused"))
return STATE_CRITICAL;
/* Network is unreachable */
else if (strstr (input_buffer, "Network is unreachable"))
return STATE_CRITICAL;
/* Internal server failure */
else if (strstr (input_buffer, "Server failure"))
return STATE_CRITICAL;
/* DNS server refused to service request */
else if (strstr (input_buffer, "Refused"))
return STATE_CRITICAL;
/* Request error */
else if (strstr (input_buffer, "Format error"))
return STATE_WARNING;
else
return STATE_OK;
}
/* process command-line arguments */
int
process_arguments (int argc, char **argv)
{
int c;
int opt_index = 0;
static struct option long_opts[] = {
{"help", no_argument, 0, 'h'},
{"version", no_argument, 0, 'V'},
{"verbose", no_argument, 0, 'v'},
{"timeout", required_argument, 0, 't'},
{"hostname", required_argument, 0, 'H'},
{"server", required_argument, 0, 's'},
{"reverse-server", required_argument, 0, 'r'},
{"expected-address", required_argument, 0, 'a'},
{0, 0, 0, 0}
};
if (argc < 2)
return ERROR;
for (c = 1; c < argc; c++)
if (strcmp ("-to", argv[c]) == 0)
strcpy (argv[c], "-t");
while (1) {
c = getopt_long (argc, argv, "hVvt:H:s:r:a:", long_opts, &opt_index);
if (c == -1 || c == EOF)
break;
switch (c) {
case '?': /* args not parsable */
printf ("%s: Unknown argument: %s\n\n", progname, optarg);
print_usage ();
exit (STATE_UNKNOWN);
case 'h': /* help */
print_help ();
exit (STATE_OK);
case 'V': /* version */
print_revision (progname, REVISION);
exit (STATE_OK);
case 'v': /* version */
verbose = TRUE;
break;
case 't': /* timeout period */
timeout_interval = atoi (optarg);
break;
case 'H': /* hostname */
if (is_host (optarg) == FALSE) {
printf ("Invalid host name/address\n\n");
print_usage ();
exit (STATE_UNKNOWN);
}
if (strlen (optarg) >= ADDRESS_LENGTH)
terminate (STATE_UNKNOWN, "Input buffer overflow\n");
strcpy (query_address, optarg);
break;
case 's': /* server name */
if (is_host (optarg) == FALSE) {
printf ("Invalid server name/address\n\n");
print_usage ();
exit (STATE_UNKNOWN);
}
if (strlen (optarg) >= ADDRESS_LENGTH)
terminate (STATE_UNKNOWN, "Input buffer overflow\n");
strcpy (dns_server, optarg);
break;
case 'r': /* reverse server name */
if (is_host (optarg) == FALSE) {
printf ("Invalid host name/address\n\n");
print_usage ();
exit (STATE_UNKNOWN);
}
if (strlen (optarg) >= ADDRESS_LENGTH)
terminate (STATE_UNKNOWN, "Input buffer overflow\n");
strcpy (ptr_server, optarg);
break;
case 'a': /* expected address */
if (is_addr (optarg) == FALSE) {
printf ("Invalid expected address\n\n");
print_usage ();
exit (STATE_UNKNOWN);
}
if (strlen (optarg) >= ADDRESS_LENGTH)
terminate (STATE_UNKNOWN, "Input buffer overflow\n");
strcpy (expected_address, optarg);
match_expected_address = TRUE;
break;
}
}
c = optind;
if (strlen(query_address)==0 && c<argc) {
if (is_host(argv[c])==FALSE) {
printf ("Invalid name/address: %s\n\n", argv[c]);
return ERROR;
}
if (strlen(argv[c])>=ADDRESS_LENGTH)
terminate (STATE_UNKNOWN, "Input buffer overflow\n");
strcpy (query_address, argv[c++]);
}
if (strlen(dns_server)==0 && c<argc) {
if (is_host(argv[c]) == FALSE) {
printf ("Invalid name/address: %s\n\n", argv[c]);
return ERROR;
}
if (strlen(argv[c]) >= ADDRESS_LENGTH)
terminate (STATE_UNKNOWN, "Input buffer overflow\n");
strcpy (dns_server, argv[c++]);
}
return validate_arguments ();
}
int
validate_arguments ()
{
if (query_address[0] == 0)
return ERROR;
else
return OK;
}
void
print_usage (void)
{
printf ("Usage: %s -H host [-s server] [-a expected-address] [-t timeout]\n" " %s --help\n"
" %s --version\n", progname, progname, progname);
}
void
print_help (void)
{
print_revision (progname, REVISION);
printf ("Copyright (c) 1999 Ethan Galstad (nagios@nagios.org)\n\n");
print_usage ();
printf
("\nOptions:\n"
"-H, --hostname=HOST\n"
" The name or address you want to query\n"
"-s, --server=HOST\n"
" Optional DNS server you want to use for the lookup\n"
"-a, --expected-address=IP-ADDRESS\n"
" Optional IP address you expect the DNS server to return\n"
"-t, --timeout=INTEGER\n"
" Seconds before connection times out (default: %d)\n"
"-h, --help\n"
" Print detailed help\n"
"-V, --version\n"
" Print version numbers and license information\n"
"\n"
"This plugin uses the nslookup program to obtain the IP address\n"
"for the given host/domain query. A optional DNS server to use may\n"
"be specified. If no DNS server is specified, the default server(s)\n"
"specified in /etc/resolv.conf will be used.\n", DEFAULT_SOCKET_TIMEOUT);
}
|