dns.h File Reference

DNS support for Asterisk. More...

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Functions
int	ast_search_dns (void *context, const char *dname, int class, int type, int(*callback)(void *context, unsigned char *answer, int len, unsigned char *fullanswer))
	Perform DNS lookup (used by DNS, enum and SRV lookups).

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Detailed Description

DNS support for Asterisk.

Author:

Thorsten Lockert <tholo@trollphone.org>

Definition in file dns.h.

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Function Documentation

int ast_search_dns	(	void *	context,
		const char *	dname,
		int	class,
		int	type,
		int(*)(void *context, unsigned char *answer, int len, unsigned char *fullanswer)	callback
	)

Perform DNS lookup (used by DNS, enum and SRV lookups).

Parameters:

	context
	dname	Domain name to lookup (host, SRV domain, TXT record name)
	class	Record Class (see "man res_search")
	type	Record type (see "man res_search")
	callback	Callback function for handling DNS result

Note:

Asterisk DNS is synchronus at this time. This means that if your DNS services does not work, Asterisk may lock while waiting for response.

Perform DNS lookup (used by DNS, enum and SRV lookups).

Note:

Asterisk DNS is synchronus at this time. This means that if your DNS does not work properly, Asterisk might not start properly or a channel may lock.

Definition at line 255 of file dns.c.

References ast_debug, ast_log(), ast_mutex_lock(), ast_mutex_unlock(), dns_parse_answer(), LOG_WARNING, and MAX_SIZE.

Referenced by ast_get_enum(), ast_get_srv(), blr_ebl(), and blr_txt().

{
#ifdef HAVE_RES_NINIT
   struct __res_state dnsstate;
#endif
   unsigned char answer[MAX_SIZE];
   int res, ret = -1;

#ifdef HAVE_RES_NINIT
   memset(&dnsstate, 0, sizeof(dnsstate));
   res_ninit(&dnsstate);
   res = res_nsearch(&dnsstate, dname, class, type, answer, sizeof(answer));
#else
   ast_mutex_lock(&res_lock);
   res_init();
   res = res_search(dname, class, type, answer, sizeof(answer));
#endif
   if (res > 0) {
      if ((res = dns_parse_answer(context, class, type, answer, res, callback)) < 0) {
         ast_log(LOG_WARNING, "DNS Parse error for %s\n", dname);
         ret = -1;
      } else if (res == 0) {
         ast_debug(1, "No matches found in DNS for %s\n", dname);
         ret = 0;
      } else
         ret = 1;
   }
#ifdef HAVE_RES_NINIT
#ifdef HAVE_RES_NDESTROY
   res_ndestroy(&dnsstate);
#else
   res_nclose(&dnsstate);
#endif
#else
#ifndef __APPLE__
   res_close();
#endif
   ast_mutex_unlock(&res_lock);
#endif

   return ret;
}