2 files changed, 246 insertions, 158 deletions

diff --git a/plugins/check_dns.c b/plugins/check_dns.c
index e1e7c00e..a4c8e9b1 100644
--- a/plugins/check_dns.c
+++ b/plugins/check_dns.c
@@ -39,26 +39,22 @@ const char *email = "devel@monitoring-plugins.org";
 #include "netutils.h"
 #include "runcmd.h"
 
-static int process_arguments(int /*argc*/, char ** /*argv*/);
-static int validate_arguments(void);
-static int error_scan(char * /*input_buffer*/, bool *);
+#include "states.h"
+#include "check_dns.d/config.h"
+
+typedef struct {
+        int errorcode;
+        check_dns_config config;
+} check_dns_config_wrapper;
+static check_dns_config_wrapper process_arguments(int /*argc*/, char ** /*argv*/);
+static check_dns_config_wrapper validate_arguments(check_dns_config_wrapper /*config_wrapper*/);
+static mp_state_enum error_scan(char * /*input_buffer*/, bool * /*is_nxdomain*/, const char /*dns_server*/[ADDRESS_LENGTH]);
 static bool ip_match_cidr(const char * /*addr*/, const char * /*cidr_ro*/);
 static unsigned long ip2long(const char * /*src*/);
 static void print_help(void);
 void print_usage(void);
 
-#define ADDRESS_LENGTH 256
-static char query_address[ADDRESS_LENGTH] = "";
-static char dns_server[ADDRESS_LENGTH] = "";
-static char ptr_server[ADDRESS_LENGTH] = "";
 static bool verbose = false;
-static char **expected_address = NULL;
-static int expected_address_cnt = 0;
-static bool expect_nxdomain = false;
-
-static bool expect_authority = false;
-static bool all_match = false;
-static thresholds *time_thresholds = NULL;
 
 static int qstrcmp(const void *p1, const void *p2) {
         /* The actual arguments to this function are "pointers to
@@ -68,23 +64,6 @@ static int qstrcmp(const void *p1, const void *p2) {
 }
 
 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 *temp_buffer = NULL;
-        bool non_authoritative = false;
-        int result = STATE_UNKNOWN;
-        double elapsed_time;
-        long microsec;
-        struct timeval tv;
-        bool parse_address = false; /* This flag scans for Address: but only after Name: */
-        output chld_out;
-        output chld_err;
-        bool is_nxdomain = false;
-
         setlocale(LC_ALL, "");
         bindtextdomain(PACKAGE, LOCALEDIR);
         textdomain(PACKAGE);
@@ -97,39 +76,62 @@ int main(int argc, char **argv) {
         /* Parse extra opts if any */
         argv = np_extra_opts(&argc, argv, progname);
 
-        if (process_arguments(argc, argv) == ERROR) {
+        check_dns_config_wrapper tmp = process_arguments(argc, argv);
+
+        if (tmp.errorcode == ERROR) {
                 usage_va(_("Could not parse arguments"));
         }
 
+        const check_dns_config config = tmp.config;
+
+        char *command_line = NULL;
         /* get the command to run */
-        xasprintf(&command_line, "%s %s %s", NSLOOKUP_COMMAND, query_address, dns_server);
+        xasprintf(&command_line, "%s %s %s", NSLOOKUP_COMMAND, config.query_address, config.dns_server);
 
+        struct timeval tv;
         alarm(timeout_interval);
         gettimeofday(&tv, NULL);
 
-        if (verbose)
+        if (verbose) {
                 printf("%s\n", command_line);
+        }
 
+        output chld_out;
+        output chld_err;
+        char *msg = NULL;
+        mp_state_enum result = STATE_UNKNOWN;
         /* run the command */
         if ((np_runcmd(command_line, &chld_out, &chld_err, 0)) != 0) {
                 msg = (char *)_("nslookup returned an error status");
                 result = STATE_WARNING;
         }
 
-        /* scan stdout */
+        /* =====
+         * scan stdout, main results get retrieved here
+         * =====
+         */
+        char *address = NULL;    /* comma separated str with addrs/ptrs (sorted) */
+        char **addresses = NULL; // All addresses parsed from stdout
+        size_t n_addresses = 0;  // counter for retrieved addresses
+        bool non_authoritative = false;
+        bool is_nxdomain = false;
+        bool parse_address = false; /* This flag scans for Address: but only after Name: */
         for (size_t i = 0; i < chld_out.lines; i++) {
-                if (addresses == NULL)
+                if (addresses == NULL) {
                         addresses = malloc(sizeof(*addresses) * 10);
-                else if (!(n_addresses % 10))
+                } else if (!(n_addresses % 10)) {
                         addresses = realloc(addresses, sizeof(*addresses) * (n_addresses + 10));
+                }
 
-                if (verbose)
+                if (verbose) {
                         puts(chld_out.line[i]);
+                }
 
                 if (strcasestr(chld_out.line[i], ".in-addr.arpa") || strcasestr(chld_out.line[i], ".ip6.arpa")) {
-                        if ((temp_buffer = strstr(chld_out.line[i], "name = ")))
+                        char *temp_buffer = NULL;
+                        if ((temp_buffer = strstr(chld_out.line[i], "name = "))) {
                                 addresses[n_addresses++] = strdup(temp_buffer + 7);
-                        else {
+                        } else {
                                 msg = (char *)_("Warning plugin error");
                                 result = STATE_WARNING;
                         }
@@ -137,37 +139,47 @@ int main(int argc, char **argv) {
 
                 /* bug ID: 2946553 - Older versions of bind will use all available dns
                                                          servers, we have to match the one specified */
-                if (strstr(chld_out.line[i], "Server:") && strlen(dns_server) > 0) {
-                        temp_buffer = strchr(chld_out.line[i], ':');
+                if (strstr(chld_out.line[i], "Server:") && strlen(config.dns_server) > 0) {
+                        char *temp_buffer = strchr(chld_out.line[i], ':');
+                        if (temp_buffer == NULL) {
+                                die(STATE_UNKNOWN, _("'%s' returned a weirdly formatted Server line\n"), NSLOOKUP_COMMAND);
+                        }
+
                         temp_buffer++;
 
                         /* Strip leading tabs */
-                        for (; *temp_buffer != '\0' && *temp_buffer == '\t'; temp_buffer++)
+                        for (; *temp_buffer != '\0' && *temp_buffer == '\t'; temp_buffer++) {
                                 /* NOOP */;
+                        }
 
                         strip(temp_buffer);
-                        if (temp_buffer == NULL || strlen(temp_buffer) == 0) {
+                        if (strlen(temp_buffer) == 0) {
                                 die(STATE_CRITICAL, _("DNS CRITICAL - '%s' returned empty server string\n"), NSLOOKUP_COMMAND);
                         }
 
-                        if (strcmp(temp_buffer, dns_server) != 0) {
-                                die(STATE_CRITICAL, _("DNS CRITICAL - No response from DNS %s\n"), dns_server);
+                        if (strcmp(temp_buffer, config.dns_server) != 0) {
+                                die(STATE_CRITICAL, _("DNS CRITICAL - No response from DNS %s\n"), config.dns_server);
                         }
                 }
 
                 /* the server is responding, we just got the host name... */
-                if (strstr(chld_out.line[i], "Name:"))
+                if (strstr(chld_out.line[i], "Name:")) {
                         parse_address = true;
-                else if (parse_address && (strstr(chld_out.line[i], "Address:") || strstr(chld_out.line[i], "Addresses:"))) {
-                        temp_buffer = index(chld_out.line[i], ':');
+                } else if (parse_address && (strstr(chld_out.line[i], "Address:") || strstr(chld_out.line[i], "Addresses:"))) {
+                        char *temp_buffer = strchr(chld_out.line[i], ':');
+                        if (temp_buffer == NULL) {
+                                die(STATE_UNKNOWN, _("'%s' returned a weirdly formatted Address line\n"), NSLOOKUP_COMMAND);
+                        }
+
                         temp_buffer++;
 
                         /* Strip leading spaces */
-                        while (*temp_buffer == ' ')
+                        while (*temp_buffer == ' ') {
                                 temp_buffer++;
+                        }
 
                         strip(temp_buffer);
-                        if (temp_buffer == NULL || strlen(temp_buffer) == 0) {
+                        if (strlen(temp_buffer) == 0) {
                                 die(STATE_CRITICAL, _("DNS CRITICAL - '%s' returned empty host name string\n"), NSLOOKUP_COMMAND);
                         }
 
@@ -176,65 +188,71 @@ int main(int argc, char **argv) {
                         non_authoritative = true;
                 }
 
-                result = error_scan(chld_out.line[i], &is_nxdomain);
+                result = error_scan(chld_out.line[i], &is_nxdomain, config.dns_server);
                 if (result != STATE_OK) {
                         msg = strchr(chld_out.line[i], ':');
-                        if (msg)
+                        if (msg) {
                                 msg++;
+                        }
                         break;
                 }
         }
 
+        char input_buffer[MAX_INPUT_BUFFER];
         /* scan stderr */
         for (size_t i = 0; i < chld_err.lines; i++) {
-                if (verbose)
+                if (verbose) {
                         puts(chld_err.line[i]);
+                }
 
-                if (error_scan(chld_err.line[i], &is_nxdomain) != STATE_OK) {
-                        result = max_state(result, error_scan(chld_err.line[i], &is_nxdomain));
+                if (error_scan(chld_err.line[i], &is_nxdomain, config.dns_server) != STATE_OK) {
+                        result = max_state(result, error_scan(chld_err.line[i], &is_nxdomain, config.dns_server));
                         msg = strchr(input_buffer, ':');
-                        if (msg)
+                        if (msg) {
                                 msg++;
-                        else
+                        } else {
                                 msg = input_buffer;
+                        }
                 }
         }
 
-        if (is_nxdomain && !expect_nxdomain) {
-                die(STATE_CRITICAL, _("Domain '%s' was not found by the server\n"), query_address);
+        if (is_nxdomain && !config.expect_nxdomain) {
+                die(STATE_CRITICAL, _("Domain '%s' was not found by the server\n"), config.query_address);
         }
 
         if (addresses) {
-                int i;
-                int slen;
-                char *adrp;
+                size_t slen = 1;
+                char *adrp = NULL;
                 qsort(addresses, n_addresses, sizeof(*addresses), qstrcmp);
-                for (i = 0, slen = 1; i < n_addresses; i++) {
+                for (size_t i = 0; i < n_addresses; i++) {
                         slen += strlen(addresses[i]) + 1;
                 }
+
+                // Temporary pointer adrp gets moved, address stays on the beginning
                 adrp = address = malloc(slen);
-                for (i = 0; i < n_addresses; i++) {
-                        if (i)
+                for (size_t i = 0; i < n_addresses; i++) {
+                        if (i) {
                                 *adrp++ = ',';
+                        }
                         strcpy(adrp, addresses[i]);
                         adrp += strlen(addresses[i]);
                 }
                 *adrp = 0;
-        } else
+        } else {
                 die(STATE_CRITICAL, _("DNS CRITICAL - '%s' msg parsing exited with no address\n"), NSLOOKUP_COMMAND);
+        }
 
         /* compare to expected address */
-        if (result == STATE_OK && expected_address_cnt > 0) {
+        if (result == STATE_OK && config.expected_address_cnt > 0) {
                 result = STATE_CRITICAL;
-                temp_buffer = "";
-                unsigned long expect_match = (1 << expected_address_cnt) - 1;
+                char *temp_buffer = "";
+                unsigned long expect_match = (1 << config.expected_address_cnt) - 1;
                 unsigned long addr_match = (1 << n_addresses) - 1;
 
-                for (int i = 0; i < expected_address_cnt; i++) {
-                        int j;
+                for (size_t i = 0; i < config.expected_address_cnt; i++) {
                         /* check if we get a match on 'raw' ip or cidr */
-                        for (j = 0; j < n_addresses; j++) {
-                                if (strcmp(addresses[j], expected_address[i]) == 0 || ip_match_cidr(addresses[j], expected_address[i])) {
+                        for (size_t j = 0; j < n_addresses; j++) {
+                                if (strcmp(addresses[j], config.expected_address[i]) == 0 || ip_match_cidr(addresses[j], config.expected_address[i])) {
                                         result = STATE_OK;
                                         addr_match &= ~(1 << j);
                                         expect_match &= ~(1 << i);
@@ -242,11 +260,12 @@ int main(int argc, char **argv) {
                         }
 
                         /* prepare an error string */
-                        xasprintf(&temp_buffer, "%s%s; ", temp_buffer, expected_address[i]);
+                        xasprintf(&temp_buffer, "%s%s; ", temp_buffer, config.expected_address[i]);
                 }
                 /* check if expected_address must cover all in addresses and none may be missing */
-                if (all_match && (expect_match != 0 || addr_match != 0))
+                if (config.all_match && (expect_match != 0 || addr_match != 0)) {
                         result = STATE_CRITICAL;
+                }
                 if (result == STATE_CRITICAL) {
                         /* Strip off last semicolon... */
                         temp_buffer[strlen(temp_buffer) - 2] = '\0';
@@ -254,28 +273,29 @@ int main(int argc, char **argv) {
                 }
         }
 
-        if (expect_nxdomain) {
+        if (config.expect_nxdomain) {
                 if (!is_nxdomain) {
                         result = STATE_CRITICAL;
-                        xasprintf(&msg, _("Domain '%s' was found by the server: '%s'\n"), query_address, address);
+                        xasprintf(&msg, _("Domain '%s' was found by the server: '%s'\n"), config.query_address, address);
                 } else {
-                        if (address != NULL)
+                        if (address != NULL) {
                                 free(address);
+                        }
                         address = "NXDOMAIN";
                 }
         }
 
         /* check if authoritative */
-        if (result == STATE_OK && expect_authority && non_authoritative) {
+        if (result == STATE_OK && config.expect_authority && non_authoritative) {
                 result = STATE_CRITICAL;
-                xasprintf(&msg, _("server %s is not authoritative for %s"), dns_server, query_address);
+                xasprintf(&msg, _("server %s is not authoritative for %s"), config.dns_server, config.query_address);
         }
 
-        microsec = deltime(tv);
-        elapsed_time = (double)microsec / 1.0e6;
+        long microsec = deltime(tv);
+        double elapsed_time = (double)microsec / 1.0e6;
 
         if (result == STATE_OK) {
-                result = get_status(elapsed_time, time_thresholds);
+                result = get_status(elapsed_time, config.time_thresholds);
                 if (result == STATE_OK) {
                         printf("DNS %s: ", _("OK"));
                 } else if (result == STATE_WARNING) {
@@ -284,24 +304,26 @@ int main(int argc, char **argv) {
                         printf("DNS %s: ", _("CRITICAL"));
                 }
                 printf(ngettext("%.3f second response time", "%.3f seconds response time", elapsed_time), elapsed_time);
-                printf(_(". %s returns %s"), query_address, address);
-                if ((time_thresholds->warning != 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 returns %s"), config.query_address, address);
+                if ((config.time_thresholds->warning != NULL) && (config.time_thresholds->critical != NULL)) {
+                        printf("|%s\n", fperfdata("time", elapsed_time, "s", true, config.time_thresholds->warning->end, true,
+                                                                          config.time_thresholds->critical->end, true, 0, false, 0));
+                } else if ((config.time_thresholds->warning == NULL) && (config.time_thresholds->critical != NULL)) {
+                        printf("|%s\n", fperfdata("time", elapsed_time, "s", false, 0, true, config.time_thresholds->critical->end, true, 0, false, 0));
+                } else if ((config.time_thresholds->warning != NULL) && (config.time_thresholds->critical == NULL)) {
+                        printf("|%s\n", fperfdata("time", elapsed_time, "s", true, config.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)
+                }
+        } else if (result == STATE_WARNING) {
                 printf(_("DNS WARNING - %s\n"), !strcmp(msg, "") ? _(" Probably a non-existent host/domain") : msg);
-        else if (result == STATE_CRITICAL)
+        } else if (result == STATE_CRITICAL) {
                 printf(_("DNS CRITICAL - %s\n"), !strcmp(msg, "") ? _(" Probably a non-existent host/domain") : msg);
-        else
+        } else {
                 printf(_("DNS UNKNOWN - %s\n"), !strcmp(msg, "") ? _(" Probably a non-existent host/domain") : msg);
+        }
 
-        return result;
+        exit(result);
 }
 
 bool ip_match_cidr(const char *addr, const char *cidr_ro) {
@@ -329,64 +351,69 @@ unsigned long ip2long(const char *src) {
                            : 0;
 }
 
-int error_scan(char *input_buffer, bool *is_nxdomain) {
+mp_state_enum error_scan(char *input_buffer, bool *is_nxdomain, const char dns_server[ADDRESS_LENGTH]) {
 
         const int nxdomain = strstr(input_buffer, "Non-existent") || strstr(input_buffer, "** server can't find") ||
                                                  strstr(input_buffer, "** Can't find") || strstr(input_buffer, "NXDOMAIN");
-        if (nxdomain)
+        if (nxdomain) {
                 *is_nxdomain = true;
+        }
 
         /* 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.")))
+                strstr(input_buffer, _("the `-sil[ent]' option to prevent this message from appearing."))) {
                 return STATE_OK;
+        }
 
         /* DNS server is not running... */
-        else if (strstr(input_buffer, "No response from server"))
+        else if (strstr(input_buffer, "No response from server")) {
                 die(STATE_CRITICAL, _("No response from DNS %s\n"), dns_server);
-        else if (strstr(input_buffer, "no servers could be reached"))
+        } else if (strstr(input_buffer, "no servers could be reached")) {
                 die(STATE_CRITICAL, _("No response from DNS %s\n"), dns_server);
+        }
 
         /* Host name is valid, but server doesn't have records... */
-        else if (strstr(input_buffer, "No records"))
+        else if (strstr(input_buffer, "No records")) {
                 die(STATE_CRITICAL, _("DNS %s has no records\n"), dns_server);
+        }
 
         /* Connection was refused */
         else if (strstr(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")))
+                         strstr(input_buffer, "Refused") || (strstr(input_buffer, "** server can't find") && strstr(input_buffer, ": REFUSED"))) {
                 die(STATE_CRITICAL, _("Connection to DNS %s was refused\n"), dns_server);
+        }
 
         /* Query refused (usually by an ACL in the namserver) */
-        else if (strstr(input_buffer, "Query refused"))
+        else if (strstr(input_buffer, "Query refused")) {
                 die(STATE_CRITICAL, _("Query was refused by DNS server at %s\n"), dns_server);
+        }
 
         /* No information (e.g. nameserver IP has two PTR records) */
-        else if (strstr(input_buffer, "No information"))
+        else if (strstr(input_buffer, "No information")) {
                 die(STATE_CRITICAL, _("No information returned by DNS server at %s\n"), dns_server);
+        }
 
         /* Network is unreachable */
-        else if (strstr(input_buffer, "Network is unreachable"))
+        else if (strstr(input_buffer, "Network is unreachable")) {
                 die(STATE_CRITICAL, _("Network is unreachable\n"));
+        }
 
         /* Internal server failure */
-        else if (strstr(input_buffer, "Server failure"))
+        else if (strstr(input_buffer, "Server failure")) {
                 die(STATE_CRITICAL, _("DNS failure for %s\n"), dns_server);
+        }
 
         /* Request error or the DNS lookup timed out */
-        else if (strstr(input_buffer, "Format error") || strstr(input_buffer, "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;
+check_dns_config_wrapper process_arguments(int argc, char **argv) {
         static struct option long_opts[] = {{"help", no_argument, 0, 'h'},
                                                                                 {"version", no_argument, 0, 'V'},
                                                                                 {"verbose", no_argument, 0, 'v'},
@@ -402,20 +429,34 @@ int process_arguments(int argc, char **argv) {
                                                                                 {"critical", required_argument, 0, 'c'},
                                                                                 {0, 0, 0, 0}};
 
-        if (argc < 2)
-                return ERROR;
+        check_dns_config_wrapper result = {
+                .config = check_dns_config_init(),
+                .errorcode = OK,
+        };
 
-        for (c = 1; c < argc; c++)
-                if (strcmp("-to", argv[c]) == 0)
-                        strcpy(argv[c], "-t");
+        if (argc < 2) {
+                result.errorcode = ERROR;
+                return result;
+        }
 
-        while (1) {
-                c = getopt_long(argc, argv, "hVvALnt:H:s:r:a:w:c:", long_opts, &opt_index);
+        for (int index = 1; index < argc; index++) {
+                if (strcmp("-to", argv[index]) == 0) {
+                        strcpy(argv[index], "-t");
+                }
+        }
+
+        char *warning = NULL;
+        char *critical = NULL;
+        int opt_index = 0;
+        int index = 0;
+        while (true) {
+                index = getopt_long(argc, argv, "hVvALnt:H:s:r:a:w:c:", long_opts, &opt_index);
 
-                if (c == -1 || c == EOF)
+                if (index == -1 || index == EOF) {
                         break;
+                }
 
-                switch (c) {
+                switch (index) {
                 case 'h': /* help */
                         print_help();
                         exit(STATE_UNKNOWN);
@@ -429,54 +470,63 @@ int process_arguments(int argc, char **argv) {
                         timeout_interval = atoi(optarg);
                         break;
                 case 'H': /* hostname */
-                        if (strlen(optarg) >= ADDRESS_LENGTH)
+                        if (strlen(optarg) >= ADDRESS_LENGTH) {
                                 die(STATE_UNKNOWN, _("Input buffer overflow\n"));
-                        strcpy(query_address, optarg);
+                        }
+                        strcpy(result.config.query_address, optarg);
                         break;
                 case 's': /* server name */
                         /* TODO: this host_or_die check is probably unnecessary.
                          * Better to confirm nslookup response matches */
                         host_or_die(optarg);
-                        if (strlen(optarg) >= ADDRESS_LENGTH)
+                        if (strlen(optarg) >= ADDRESS_LENGTH) {
                                 die(STATE_UNKNOWN, _("Input buffer overflow\n"));
-                        strcpy(dns_server, optarg);
+                        }
+                        strcpy(result.config.dns_server, optarg);
                         break;
                 case 'r': /* reverse server name */
                         /* TODO: Is this host_or_die necessary? */
+                        // TODO This does not do anything!!! 2025-03-08 rincewind
                         host_or_die(optarg);
-                        if (strlen(optarg) >= ADDRESS_LENGTH)
+                        if (strlen(optarg) >= ADDRESS_LENGTH) {
                                 die(STATE_UNKNOWN, _("Input buffer overflow\n"));
+                        }
+                        static char ptr_server[ADDRESS_LENGTH] = "";
                         strcpy(ptr_server, optarg);
                         break;
                 case 'a': /* expected address */
-                        if (strlen(optarg) >= ADDRESS_LENGTH)
+                        if (strlen(optarg) >= ADDRESS_LENGTH) {
                                 die(STATE_UNKNOWN, _("Input buffer overflow\n"));
+                        }
                         if (strchr(optarg, ',') != NULL) {
                                 char *comma = strchr(optarg, ',');
                                 while (comma != NULL) {
-                                        expected_address = (char **)realloc(expected_address, (expected_address_cnt + 1) * sizeof(char **));
-                                        expected_address[expected_address_cnt] = strndup(optarg, comma - optarg);
-                                        expected_address_cnt++;
+                                        result.config.expected_address =
+                                                (char **)realloc(result.config.expected_address, (result.config.expected_address_cnt + 1) * sizeof(char **));
+                                        result.config.expected_address[result.config.expected_address_cnt] = strndup(optarg, comma - optarg);
+                                        result.config.expected_address_cnt++;
                                         optarg = comma + 1;
                                         comma = strchr(optarg, ',');
                                 }
-                                expected_address = (char **)realloc(expected_address, (expected_address_cnt + 1) * sizeof(char **));
-                                expected_address[expected_address_cnt] = strdup(optarg);
-                                expected_address_cnt++;
+                                result.config.expected_address =
+                                        (char **)realloc(result.config.expected_address, (result.config.expected_address_cnt + 1) * sizeof(char **));
+                                result.config.expected_address[result.config.expected_address_cnt] = strdup(optarg);
+                                result.config.expected_address_cnt++;
                         } else {
-                                expected_address = (char **)realloc(expected_address, (expected_address_cnt + 1) * sizeof(char **));
-                                expected_address[expected_address_cnt] = strdup(optarg);
-                                expected_address_cnt++;
+                                result.config.expected_address =
+                                        (char **)realloc(result.config.expected_address, (result.config.expected_address_cnt + 1) * sizeof(char **));
+                                result.config.expected_address[result.config.expected_address_cnt] = strdup(optarg);
+                                result.config.expected_address_cnt++;
                         }
                         break;
                 case 'n': /* expect NXDOMAIN */
-                        expect_nxdomain = true;
+                        result.config.expect_nxdomain = true;
                         break;
                 case 'A': /* expect authority */
-                        expect_authority = true;
+                        result.config.expect_authority = true;
                         break;
                 case 'L': /* all must match */
-                        all_match = true;
+                        result.config.all_match = true;
                         break;
                 case 'w':
                         warning = optarg;
@@ -489,38 +539,42 @@ int process_arguments(int argc, char **argv) {
                 }
         }
 
-        c = optind;
-        if (strlen(query_address) == 0 && c < argc) {
-                if (strlen(argv[c]) >= ADDRESS_LENGTH)
+        index = optind;
+        if (strlen(result.config.query_address) == 0 && index < argc) {
+                if (strlen(argv[index]) >= ADDRESS_LENGTH) {
                         die(STATE_UNKNOWN, _("Input buffer overflow\n"));
-                strcpy(query_address, argv[c++]);
+                }
+                strcpy(result.config.query_address, argv[index++]);
         }
 
-        if (strlen(dns_server) == 0 && c < argc) {
+        if (strlen(result.config.dns_server) == 0 && index < argc) {
                 /* TODO: See -s option */
-                host_or_die(argv[c]);
-                if (strlen(argv[c]) >= ADDRESS_LENGTH)
+                host_or_die(argv[index]);
+                if (strlen(argv[index]) >= ADDRESS_LENGTH) {
                         die(STATE_UNKNOWN, _("Input buffer overflow\n"));
-                strcpy(dns_server, argv[c++]);
+                }
+                strcpy(result.config.dns_server, argv[index++]);
         }
 
-        set_thresholds(&time_thresholds, warning, critical);
+        set_thresholds(&result.config.time_thresholds, warning, critical);
 
-        return validate_arguments();
+        return validate_arguments(result);
 }
 
-int validate_arguments(void) {
-        if (query_address[0] == 0) {
+check_dns_config_wrapper validate_arguments(check_dns_config_wrapper config_wrapper) {
+        if (config_wrapper.config.query_address[0] == 0) {
                 printf("missing --host argument\n");
-                return ERROR;
+                config_wrapper.errorcode = ERROR;
+                return config_wrapper;
         }
 
-        if (expected_address_cnt > 0 && expect_nxdomain) {
+        if (config_wrapper.config.expected_address_cnt > 0 && config_wrapper.config.expect_nxdomain) {
                 printf("--expected-address and --expect-nxdomain cannot be combined\n");
-                return ERROR;
+                config_wrapper.errorcode = ERROR;
+                return config_wrapper;
         }
 
-        return OK;
+        return config_wrapper;
 }
 
 void print_help(void) {
diff --git a/plugins/check_dns.d/config.h b/plugins/check_dns.d/config.h
new file mode 100644
index 00000000..9ec4eb82
--- /dev/null
+++ b/plugins/check_dns.d/config.h
@@ -0,0 +1,34 @@
+#pragma once
+
+#include "../../config.h"
+#include "thresholds.h"
+#include <stddef.h>
+
+#define ADDRESS_LENGTH 256
+
+typedef struct {
+        bool all_match;
+        char dns_server[ADDRESS_LENGTH];
+        char query_address[ADDRESS_LENGTH];
+        bool expect_nxdomain;
+        bool expect_authority;
+        char **expected_address;
+        size_t expected_address_cnt;
+
+        thresholds *time_thresholds;
+} check_dns_config;
+
+check_dns_config check_dns_config_init() {
+        check_dns_config tmp = {
+                .all_match = false,
+                .dns_server = "",
+                .query_address = "",
+                .expect_nxdomain = false,
+                .expect_authority = false,
+                .expected_address = NULL,
+                .expected_address_cnt = 0,
+
+                .time_thresholds = NULL,
+        };
+        return tmp;
+}