Mon Jun 27 16:51:13 2011

Asterisk developer's documentation


dns.h File Reference

DNS support for Asterisk. More...

Go to the source code of this file.

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).


Detailed Description

DNS support for Asterisk.

Author:
Thorsten Lockert <tholo@trollphone.org>

Definition in file dns.h.


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).

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(), ast_srv_lookup(), blr_ebl(), and blr_txt().

00258 {
00259 #ifdef HAVE_RES_NINIT
00260    struct __res_state dnsstate;
00261 #endif
00262    unsigned char answer[MAX_SIZE];
00263    int res, ret = -1;
00264 
00265 #ifdef HAVE_RES_NINIT
00266    memset(&dnsstate, 0, sizeof(dnsstate));
00267    res_ninit(&dnsstate);
00268    res = res_nsearch(&dnsstate, dname, class, type, answer, sizeof(answer));
00269 #else
00270    ast_mutex_lock(&res_lock);
00271    res_init();
00272    res = res_search(dname, class, type, answer, sizeof(answer));
00273 #endif
00274    if (res > 0) {
00275       if ((res = dns_parse_answer(context, class, type, answer, res, callback)) < 0) {
00276          ast_log(LOG_WARNING, "DNS Parse error for %s\n", dname);
00277          ret = -1;
00278       } else if (res == 0) {
00279          ast_debug(1, "No matches found in DNS for %s\n", dname);
00280          ret = 0;
00281       } else
00282          ret = 1;
00283    }
00284 #ifdef HAVE_RES_NINIT
00285 #ifdef HAVE_RES_NDESTROY
00286    res_ndestroy(&dnsstate);
00287 #else
00288    res_nclose(&dnsstate);
00289 #endif
00290 #else
00291 #ifdef HAVE_RES_CLOSE
00292    res_close();
00293 #endif
00294    ast_mutex_unlock(&res_lock);
00295 #endif
00296 
00297    return ret;
00298 }


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