/***************************************************************************** * * Nagios check_dns plugin * * License: GPL * Copyright (c) 2000-2018 Nagios Plugins Development Team * * Description: * * This file contains the check_dns plugin * * LIMITATION: nslookup on Solaris 7 can return output over 2 lines, which * will not be picked up by this plugin * * * 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 3 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, see . * * *****************************************************************************/ #define IF_RECORD(label, querytype, verb_str, comp_str) if (strstr (chld_out.line[i], label) && (strncmp(query_type, querytype, query_size) == 0 || strncmp(query_type, "-querytype=ANY", query_size) == 0)) { \ if (verbose) { \ printf(verb_str); \ } \ temp_buffer = rindex (chld_out.line[i], comp_str); \ addresses[n_addresses++] = check_new_address(temp_buffer); \ memset(query_found, '\0', sizeof(query_found)); \ strncpy(query_found, querytype, sizeof(query_found)); const char *progname = "check_dns"; const char *copyright = "2000-2018"; const char *email = "devel@nagios-plugins.org"; #include "common.h" #include "utils.h" #include "utils_base.h" #include "netutils.h" #include "runcmd.h" int process_arguments (int, char **); int validate_arguments (void); int error_scan (char *); void print_help (void); void print_usage (void); /* Allow up to 4096 input length, this is helpful when the TXT records returned have multiple 255 legth values returned */ #define ADDRESS_LENGTH 4096 char query_address[ADDRESS_LENGTH] = ""; char dns_server[ADDRESS_LENGTH] = ""; char tmp_dns_server[ADDRESS_LENGTH] = ""; char ptr_server[ADDRESS_LENGTH] = ""; char query_type[32] = ""; int query_set = FALSE; int verbose = FALSE; char **expected_address = NULL; int expected_address_cnt = 0; int expect_authority = FALSE; int accept_cname = FALSE; thresholds *time_thresholds = NULL; static int qstrcmp(const void *p1, const void *p2) { /* The actual arguments to this function are "pointers to pointers to char", but strcmp() arguments are "pointers to char", hence the following cast plus dereference */ return strcmp(* (char * const *) p1, * (char * const *) p2); } char * check_new_address(char *temp_buffer) { temp_buffer++; /* Strip leading spaces */ for (; *temp_buffer != '\0' && *temp_buffer == ' '; temp_buffer++) { /* NOOP */; } strip(temp_buffer); if (temp_buffer==NULL || strlen(temp_buffer)==0) { die (STATE_CRITICAL, "%s%s%s\n", _("DNS CRITICAL - '"), NSLOOKUP_COMMAND, _("' returned empty host name string")); } return temp_buffer; } int main (int argc, char **argv) { char *command_line = NULL; char input_buffer[MAX_INPUT_BUFFER]; char *address = NULL; /* comma separated str with addrs/ptrs (sorted) */ char **addresses = NULL; int n_addresses = 0; char *msg = NULL; char query_found[24] = ""; int query_size = 24; char *temp_buffer = NULL; int non_authoritative = FALSE; int result = STATE_UNKNOWN; double elapsed_time; long microsec; struct timeval tv; int parse_address = FALSE; /* This flag scans for Address: but only after Name: */ output chld_out, chld_err; size_t i; setlocale (LC_ALL, ""); bindtextdomain (PACKAGE, LOCALEDIR); textdomain (PACKAGE); /* Set signal handling and alarm */ if (signal (SIGALRM, runcmd_timeout_alarm_handler) == SIG_ERR) { usage_va(_("Cannot catch SIGALRM")); } /* Parse extra opts if any */ argv=np_extra_opts (&argc, argv, progname); if (process_arguments (argc, argv) == ERROR) { usage_va(_("Could not parse arguments")); } /* get the command to run */ xasprintf (&command_line, "%s %s %s %s", NSLOOKUP_COMMAND, query_type, query_address, dns_server); alarm (timeout_interval); gettimeofday (&tv, NULL); if (verbose) { printf ("%s\n", command_line); } /* run the command */ if((np_runcmd(command_line, &chld_out, &chld_err, 0)) != 0) { msg = strdup(_("nslookup returned an error status")); result = STATE_WARNING; } /* scan stdout */ for(i = 0; i < chld_out.lines; i++) { if (addresses == NULL) { addresses = malloc(sizeof(*addresses)*10); } else if (!(n_addresses % 10)) { addresses = realloc(addresses,sizeof(*addresses) * (n_addresses + 10)); } if (verbose) { puts(chld_out.line[i]); } /* bug ID: 2946553 - Older versions of bind will use all available dns + servers, we have to match the one specified */ if (strlen(dns_server) > 0 && strstr(chld_out.line[i], "Server:")) { temp_buffer = strchr(chld_out.line[i], ':'); temp_buffer++; if (temp_buffer > (char *)1) { /* Strip leading tabs */ for (; *temp_buffer != '\0' && *temp_buffer == '\t'; temp_buffer++) { /* NOOP */; } strip(temp_buffer); if (temp_buffer==NULL || strlen(temp_buffer)==0) { die (STATE_CRITICAL, "%s%s%s\n", _("DNS CRITICAL - '"), NSLOOKUP_COMMAND, _("' returned empty server string")); } if (strcmp(temp_buffer, dns_server) != 0) { die (STATE_CRITICAL, "%s %s\n", _("DNS CRITICAL - No response from DNS server:"), dns_server); } } } /* Provide the server name\ip to error_scan when not using -s */ else if (strlen(tmp_dns_server) == 0) { temp_buffer = strchr(chld_out.line[i], ':'); temp_buffer++; if (temp_buffer > (char *)1) { /* Strip leading tabs */ for (; *temp_buffer != '\0' && *temp_buffer == '\t'; temp_buffer++) { /* NOOP */; } strip(temp_buffer); strncpy(tmp_dns_server, temp_buffer, ADDRESS_LENGTH); } } if (strstr (chld_out.line[i], "Authoritative answers can be found from:")) { break; } /* the server is responding, we just got the host name...*/ if (strstr (chld_out.line[i], "Name:")) { parse_address = TRUE; } /* begin handling types of records */ IF_RECORD("AAAA address", "-querytype=AAAA", "Found AAAA record\n", ' ') } else IF_RECORD("exchanger =", "-querytype=MX", "Found MX record\n", '=') } else IF_RECORD("service =", "-querytype=SRV", "Found SRV record\n", ' ') } else IF_RECORD("nameserver =", "-querytype=NS", "Found NS record\n", ' ') } else IF_RECORD("dname =", "-querytype=DNAME", "Found DNAME record\n", ' ') } else IF_RECORD("protocol =", "-querytype=WKS", "Found WKS record\n", ' ') } else if (strstr (chld_out.line[i], "text =") && (strncmp(query_type, "-querytype=TXT", query_size) == 0 || strncmp(query_type, "-querytype=ANY", query_size) == 0)) { if (verbose) { printf("Found TXT record\n"); } temp_buffer = index(chld_out.line[i], '"'); --temp_buffer; addresses[n_addresses++] = check_new_address(temp_buffer); memset(query_found, '\0', sizeof(query_found)); strncpy(query_found, "-querytype=TXT", sizeof(query_found)); } /* only matching for origin records, if requested other fields could be included at a later date */ else IF_RECORD("origin =", "-querytype=SOA", "Found SOA record\n", ' ') } /* cnames cannot use macro as we must check for accepting them separately */ else if (accept_cname && strstr (chld_out.line[i], "canonical name =") && (strncmp(query_type, "-querytype=CNAME", query_size) == 0 || strncmp(query_type, "-querytype=ANY", query_size) == 0)) { if (verbose) { printf("Found CNAME record\n"); } temp_buffer = index (chld_out.line[i], '='); addresses[n_addresses++] = check_new_address(temp_buffer); strncpy(query_found, "-querytype=CNAME", sizeof(query_found)); } /* does not need strncmp as we want A at all times unless another record match */ else if (parse_address == TRUE && (strstr (chld_out.line[i], "Address:") || strstr (chld_out.line[i], "Addresses:"))) { temp_buffer = index (chld_out.line[i], ':'); char *temp_address = check_new_address(temp_buffer); addresses[n_addresses++] = temp_address; /* Bind 9.11.x onwards reports AAAA records the same as A records */ /* It is assumed that nslookup returns a valid IPv4 or IPv6 address */ /* Hence we'll look for a colon : in the address to detect an IPv6 address */ if (strstr(temp_address, ":")) { if (verbose) { printf("Found AAAA record\n"); } strncpy(query_found, "-querytype=AAAA", sizeof(query_found)); } else { if (verbose) { printf("Found A record\n"); } strncpy(query_found, "-querytype=A", sizeof(query_found)); } } /* must be after other records with "name" as an identifier, as ptr does not spefify */ else IF_RECORD("name =", "-querytype=PTR", "Found PTR record\n", ' ') } /* needed for non-query ptr\reverse lookup checks */ else if (strstr(chld_out.line[i], ".in-addr.arpa") && !query_set) { if ((temp_buffer = strstr(chld_out.line[i], "name = "))) { addresses[n_addresses++] = strdup(temp_buffer); } else { xasprintf(&msg, "%s %s %s %s", _("Warning plugin error")); result = STATE_WARNING; } } if (strstr (chld_out.line[i], _("Non-authoritative answer:"))) { non_authoritative = TRUE; } int tmp = error_scan(chld_out.line[i]); if (result == STATE_UNKNOWN || result < tmp) { result = tmp; if (result != STATE_OK) { msg = strchr (chld_out.line[i], ':'); if (msg) { msg++; } else { msg = chld_out.line[i]; } break; } } } /*This is the end of the scan stdout loop */ /* scan stderr */ for(i = 0; i < chld_err.lines; i++) { if (verbose) { puts(chld_err.line[i]); } if (error_scan (chld_err.line[i]) != STATE_OK) { result = max_state (result, error_scan (chld_err.line[i])); msg = strchr(chld_err.line[i], ':'); if(msg) { msg++; } else { msg = chld_err.line[i]; } } } if (addresses) { int i,slen; char *adrp; qsort(addresses, n_addresses, sizeof(*addresses), qstrcmp); for(i=0, slen=1; i < n_addresses; i++) { slen += strlen(addresses[i])+1; } adrp = address = malloc(slen); for(i=0; i < n_addresses; i++) { if (i) *adrp++ = ','; strcpy(adrp, addresses[i]); adrp += strlen(addresses[i]); } *adrp = 0; } else { die (STATE_CRITICAL, "%s%s%s\n", _("DNS CRITICAL - '"), NSLOOKUP_COMMAND, _("' msg parsing exited with no address")); } /* compare to expected address */ if (result == STATE_OK && expected_address_cnt > 0) { result = STATE_CRITICAL; temp_buffer = ""; for (i=0; iwarning != NULL) && (time_thresholds->critical != NULL)) { printf ("|%s\n", fperfdata ("time", elapsed_time, "s", TRUE, time_thresholds->warning->end, TRUE, time_thresholds->critical->end, TRUE, 0, FALSE, 0)); } else if ((time_thresholds->warning == NULL) && (time_thresholds->critical != NULL)) { printf ("|%s\n", fperfdata ("time", elapsed_time, "s", FALSE, 0, TRUE, time_thresholds->critical->end, TRUE, 0, FALSE, 0)); } else if ((time_thresholds->warning != NULL) && (time_thresholds->critical == NULL)) { printf ("|%s\n", fperfdata ("time", elapsed_time, "s", TRUE, time_thresholds->warning->end, FALSE, 0, TRUE, 0, FALSE, 0)); } else { printf ("|%s\n", fperfdata ("time", elapsed_time, "s", FALSE, 0, FALSE, 0, TRUE, 0, FALSE, 0)); } } else if (result == STATE_WARNING) { printf ("%s %s\n", _("DNS WARNING -"), !strcmp (msg, "") ? _("Probably a non-existent host/domain") : msg); } else if (result == STATE_CRITICAL) { printf ("%s %s\n", _("DNS CRITICAL -"), !strcmp (msg, "") ? _("Probably a non-existent host/domain") : msg); } else { printf ("%s %s\n", _("DNS UNKNOWN -"), !strcmp (msg, "") ? _("Probably a non-existent host/domain") : msg); } return result; } int error_scan (char *input_buffer) { 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 (strcasestr (input_buffer, "connection timed out")) { die (STATE_CRITICAL, "%s %s %s\n", _("Connection to DNS"), (strlen(dns_server)==0)?tmp_dns_server:dns_server, _("timed out")); } /* DNS server is not running... */ else if (strstr (input_buffer, "No response from server")) { die (STATE_CRITICAL, "%s %s\n", _("No response from DNS"), (strlen(dns_server)==0)?tmp_dns_server:dns_server); } /* Host name is valid, but server doesn't have records... */ else if (strstr (input_buffer, "No records") || strstr (input_buffer, "No answer")) { die (STATE_CRITICAL, "%s %s %s\n", _("DNS"), (strlen(dns_server)==0)?tmp_dns_server:dns_server, _("has no records")); } /* Connection was refused */ else if (strcasestr (input_buffer, "Connection refused") || strstr (input_buffer, "Couldn't find server") || strstr (input_buffer, "Refused") || (strstr (input_buffer, "** server can't find") && strstr (input_buffer, ": REFUSED"))) { die (STATE_CRITICAL, "%s %s %s\n", _("Connection to DNS"), (strlen(dns_server)==0)?tmp_dns_server:dns_server, _("was refused")); } /* Query refused (usually by an ACL in the namserver) */ else if (strstr (input_buffer, "Query refused")) { die (STATE_CRITICAL, "%s %s\n", _("Query was refused by DNS server at"), (strlen(dns_server)==0)?tmp_dns_server:dns_server); } /* No information (e.g. nameserver IP has two PTR records) */ else if (strstr (input_buffer, "No information")) { die (STATE_CRITICAL, "%s %s\n", _("No information returned by DNS server at"), (strlen(dns_server)==0)?tmp_dns_server:dns_server); } /* Host or domain name does not exist */ else if (strstr (input_buffer, "Non-existent") || strstr (input_buffer, "** server can't find") || strstr (input_buffer,"NXDOMAIN")) { die (STATE_CRITICAL, "%s %s %s\n", _("Domain"), query_address, _("was not found by the server")); } /* Network is unreachable */ else if (strstr (input_buffer, "Network is unreachable")) { die (STATE_CRITICAL, "%s\n", _("Network is unreachable")); } /* Internal server failure */ else if (strstr (input_buffer, "Server failure")) { die (STATE_CRITICAL, "%s %s\n", _("DNS failure for"), (strlen(dns_server)==0)?tmp_dns_server:dns_server); } /* Request error or the DNS lookup timed out */ else if (strstr (input_buffer, "Format error") || strstr (input_buffer, "Timed out")) { return STATE_WARNING; } return STATE_OK; } /* process command-line arguments */ int process_arguments (int argc, char **argv) { int c; char *warning = NULL; char *critical = NULL; 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'}, {"querytype", required_argument, 0, 'q'}, {"expected-address", required_argument, 0, 'a'}, {"expect-authority", no_argument, 0, 'A'}, {"accept-cname", no_argument, 0, 'n'}, {"warning", required_argument, 0, 'w'}, {"critical", required_argument, 0, 'c'}, {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, "hVvAnt:H:s:r:a:q:w:c:", long_opts, &opt_index); if (c == -1 || c == EOF) { break; } switch (c) { /* help */ case 'h': print_help (); exit (STATE_OK); /* version */ case 'V': print_revision (progname, NP_VERSION); exit (STATE_OK); /* verbose */ case 'v': verbose = TRUE; break; /* timeout period */ case 't': timeout_interval = parse_timeout_string (optarg); break; /* hostname */ case 'H': if (strlen (optarg) >= ADDRESS_LENGTH) { die (STATE_UNKNOWN, "%s\n", _("Input buffer overflow")); } strcpy (query_address, optarg); break; /* server name */ case 's': /* TODO: this host_or_die check is probably unnecessary. * Better to confirm nslookup response matches */ host_or_die(optarg); if (strlen (optarg) >= ADDRESS_LENGTH) { die (STATE_UNKNOWN, "%s\n", _("Input buffer overflow")); } strcpy (dns_server, optarg); break; /* reverse server name */ case 'r': /* TODO: Is this host_or_die necessary? */ host_or_die(optarg); if (strlen (optarg) >= ADDRESS_LENGTH) { die (STATE_UNKNOWN, "%s\n", _("Input buffer overflow")); } strcpy (ptr_server, optarg); break; /* expected address */ case 'a': if (strlen (optarg) >= ADDRESS_LENGTH) { die (STATE_UNKNOWN, "%s\n", _("Input buffer overflow")); } expected_address = (char **)realloc(expected_address, (expected_address_cnt+1) * sizeof(char*)); expected_address[expected_address_cnt] = strdup(optarg); expected_address_cnt++; break; /* querytype -- A or AAAA or ANY or SRV or TXT, etc. */ case 'q': if (strlen (optarg) < 1 || strlen (optarg) > 5) { die (STATE_UNKNOWN, "%s\n", _("Missing valid querytype parameter. Try using 'A' or 'AAAA' or 'SRV' or 'ANY'")); } strntoupper(optarg, strlen(optarg)); strcpy(query_type, "-querytype="); strcat(query_type, optarg); query_set = TRUE; /* logic is set such that we must accept cnames if they are querying for them */ if (strcmp(query_type, "-querytype=CNAME") != 0) { break; } /* accept cname responses as a result */ case 'n': accept_cname = TRUE; break; /* expect authority */ case 'A': expect_authority = TRUE; break; case 'w': warning = optarg; break; case 'c': critical = optarg; break; /* args not parsable */ default: usage5(); } } set_thresholds(&time_thresholds, warning, critical); return validate_arguments (); } int validate_arguments () { if (query_address[0] == 0) { return ERROR; } /* Bind 9.11.x onwards performs a query for both A and AAAA records */ /* The previous default behavior of nslookup was just A records. */ /* To ensure that exisitng users of this plugin do not get incorrect results */ /* set the querytype to A if it has not already been specified. */ /* If an end user wants both A and AAAA then they need to use ANY. */ if (strcmp(query_type, "") == 0) { /*query_type = "-querytype=A";*/ strcpy(query_type, "-querytype="); strcat(query_type, "A"); query_set = TRUE; } return OK; } void print_help (void) { print_revision (progname, NP_VERSION); printf ("%s\n", "Copyright (c) 1999 Ethan Galstad "); printf (COPYRIGHT, copyright, email); printf ("%s\n", _("This plugin uses the nslookup program to obtain the IP address for the given host/domain query.")); printf ("%s\n", _("An optional DNS server to use may be specified.")); printf ("%s\n", _("If no DNS server is specified, the default server(s) specified in /etc/resolv.conf will be used.")); printf ("\n\n"); print_usage (); printf (UT_HELP_VRSN); printf (UT_EXTRA_OPTS); printf ("%s\n", " -H, --hostname=HOST"); printf (" %s\n", _("The name or address you want to query")); printf ("%s\n", " -s, --server=HOST"); printf (" %s\n", _("Optional DNS server you want to use for the lookup")); printf ("%s\n", " -q, --querytype=TYPE"); printf (" %s\n", _("Optional DNS record query type where TYPE =(A, AAAA, SRV, TXT, MX, ANY)")); printf (" %s\n", _("The default query type is 'A' (IPv4 host entry)")); printf (" %s\n", _("BIND 9.11.x onwards supports both 'A' and 'AAAA', if you want both use 'ANY'")); printf ("%s\n", " -a, --expected-address=IP-ADDRESS|HOST"); printf (" %s\n", _("Optional IP-ADDRESS you expect the DNS server to return. HOST must end with")); printf (" %s\n", _("a dot (.). This option can be repeated multiple times (Returns OK if any")); printf (" %s\n", _("value match). If multiple addresses are returned at once, you have to match")); printf (" %s\n", _("the whole string of addresses separated with commas (sorted alphabetically).")); printf (" %s\n", _("If you would like to test for the presence of a cname, combine with -n param.")); printf ("%s\n", " -A, --expect-authority"); printf (" %s\n", _("Optionally expect the DNS server to be authoritative for the lookup")); printf ("%s\n", " -n, --accept-cname"); printf (" %s\n", _("Optionally accept cname responses as a valid result to a query")); printf (" %s\n", _("The default is to ignore cname responses as part of the result")); printf ("%s\n", " -w, --warning=seconds"); printf (" %s\n", _("Return warning if elapsed time exceeds value. Default off")); printf ("%s\n", " -c, --critical=seconds"); printf (" %s\n", _("Return critical if elapsed time exceeds value. Default off")); printf (UT_CONN_TIMEOUT, DEFAULT_SOCKET_TIMEOUT); printf (UT_SUPPORT); } void print_usage (void) { printf ("%s\n", _("Usage:")); printf ("%s %s\n", progname, "-H host [-s server] [-q type ] [-a expected-address] [-A] [-n] [-t timeout] [-w warn] [-c crit]"); }