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ARES_PARSE_CAA_REPLY(3)	   Library Functions Manual    ARES_PARSE_CAA_REPLY(3)

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 re-
       sponsibility 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_t **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_t *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)

			       16 September 2020       ARES_PARSE_CAA_REPLY(3)

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