Sat Aug 6 00:39:55 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 247 of file dns.c.

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

Referenced by ast_get_enum(), ast_get_srv(), and ast_get_txt().

00250 {
00251 #ifdef HAVE_RES_NINIT
00252    struct __res_state dnsstate;
00253 #endif
00254    unsigned char answer[MAX_SIZE];
00255    int res, ret = -1;
00256 
00257 #ifdef HAVE_RES_NINIT
00258    memset(&dnsstate, 0, sizeof(dnsstate));
00259    res_ninit(&dnsstate);
00260    res = res_nsearch(&dnsstate, dname, class, type, answer, sizeof(answer));
00261 #else
00262    ast_mutex_lock(&res_lock);
00263    res_init();
00264    res = res_search(dname, class, type, answer, sizeof(answer));
00265 #endif
00266    if (res > 0) {
00267       if ((res = dns_parse_answer(context, class, type, answer, res, callback)) < 0) {
00268          ast_log(LOG_WARNING, "DNS Parse error for %s\n", dname);
00269          ret = -1;
00270       }
00271       else if (res == 0) {
00272          ast_log(LOG_DEBUG, "No matches found in DNS for %s\n", dname);
00273          ret = 0;
00274       }
00275       else
00276          ret = 1;
00277    }
00278 #ifdef HAVE_RES_NINIT
00279 #ifdef HAVE_RES_NDESTROY
00280    res_ndestroy(&dnsstate);
00281 #else
00282    res_nclose(&dnsstate);
00283 #endif
00284 #else
00285 #ifndef __APPLE__
00286    res_close();
00287 #endif
00288    ast_mutex_unlock(&res_lock);
00289 #endif
00290 
00291    return ret;
00292 }


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