NAME

       ares_parse_caa_reply - Parse a reply to a DNS query of type CAA

SYNOPSIS

       #include <ares.h>

       int ares_parse_caa_reply(const unsigned char* abuf, int alen,
                                struct ares_caa_reply **caa_out);

DESCRIPTION

       The ares_parse_caa_reply function parses the response to a query of type CAA into a linked
       list (one element per sub-string) of struct ares_caa_reply The parameters  abuf  and  alen
       give the contents of the response.  The result is stored in allocated memory and a pointer
       to it stored into the variable pointed to by caa_out.  It is the  caller's  responsibility
       to  free  the  resulting  caa_out structure when it is no longer needed using the function
       ares_free_data(3)

       The structure ares_caa_reply(3) contains the following fields:

           struct ares_caa_reply {
             struct ares_caa_reply *next;
             int                    critical;
             unsigned char         *property;
             size_t                 plength; /* plength excludes null */
             unsigned char         *value;
             size_t                 length;  /* length excludes null */
           };

RETURN VALUES

       ares_parse_caa_reply can return any of the following values:

       ARES_SUCCESS   The response was successfully parsed.

       ARES_EBADRESP  The response was malformatted.

       ARES_ENODATA   The response did not contain an answer to the query.

       ARES_ENOMEM    Memory was exhausted.

EXAMPLE

       #include <arpa/inet.h>
       #include <time.h>
       #include <sys/time.h>
       #include <netdb.h>

       #include <unistd.h>
       #include <stdio.h>
       #include <stdlib.h>

       #include "ares.h"

       static void dns_callback(void *arg,
                                int status,
                                int timeouts,
                                unsigned char *abuf,
                                int alen)
         {
           struct ares_caa_reply *caa_out;
           int err;

           err = ares_parse_caa_reply (abuf, alen, &caa_out);
           if (err == ARES_SUCCESS)
             {
               struct ares_caa_reply *caa_curr;
               for (caa_curr=caa_out; caa_curr; caa_curr=caa_curr->next)
                 printf ("%s. CAA %i %s \"%s\"\n", arg,
                                                   caa_curr->critical,
                                                   caa_curr->property,
                                                   caa_curr->value);
             }
           else
             {
               printf ("err=%i\n", err);
             }
           ares_free_data (caa_out);
         }

       static void main_loop(ares_channel *channel)
         {
           int nfds, count;
           fd_set readers, writers;
           struct timeval tv, *tvp;
           while (1)
             {
               FD_ZERO (&readers);
               FD_ZERO (&writers);
               nfds = ares_fds (*channel, &readers, &writers);
               if (nfds == 0)
                 break;
               tvp = ares_timeout (*channel, NULL, &tv);
               count = select (nfds, &readers, &writers, NULL, tvp);
               ares_process (*channel, &readers, &writers);
             }
         }

       int main(int argc, char **argv)
         {
           const char *sversion;
           int iversion;
           int err;

           sversion = ares_version (&iversion);
           printf ("c-ares version %s\n", sversion);

           char *domain = "wikipedia.org";
           if (argc > 1)
             domain = argv[1];

           ares_channel channel;
           if ((err = ares_init (&channel)) != ARES_SUCCESS)
             {
               printf ("ares_init() failed (%i)\n", err);
               exit (EXIT_FAILURE);
             }

           ares_query (channel, domain,
                       1,   /* ns_c_in */
                       257, /* T_CAA */
                       dns_callback, domain);

           main_loop (&channel);

           ares_destroy (channel);

           exit (EXIT_SUCCESS);
         }

AVAILABILITY

       This function was first introduced in c-ares version 1.17.0.

SEE ALSO

       ares_query(3) ares_free_data(3)

AUTHOR

       Written   by   Danny   Sonnenschein   <my.card.god@web.de>,   on   behalf   of   platynum,
       https://platynum.ch

                                        16 September 2020                 ARES_PARSE_CAA_REPLY(3)