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dns_name4

dns_name4

Section: C Library Functions (3)
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NAME

dns_name4 - IP address to host name  

SYSNOPSIS

#include <dns.h>

dns_name4(&out, ip);
dns_name_packet(&out, buf, len);
dns_name4_domain(q, ip);

  stralloc out = {0};
  char ip[4];
  char q[DNS_NAME4_DOMAIN];
  char *buf;
  unsigned int len;  

DESCRIPTION

dns_name4 looks up the domain name for the 4-byte IP address in ip. It puts the (first) domain name into out and returns 0. If the relevant in-addr.arpa domain does not exist in DNS, or has no PTR records, out will be empty.

If dns_name4 has trouble with the DNS lookup or runs out of memory, it returns -1, setting errno appropriately. It may or may not change out.

dns_name_packet is a low-level component of dns_name4, designed to support asynchronous DNS lookups. It reads a DNS packet of length len from buf, extracts the first PTR record from the answer section of the packet, puts the result into out, and returns 0 or -1 the same way as dns_name4.

dns_name4_domain is another low-level component of dns_name4. It converts an IP address such as 1.2.3.4 into a domain name such as 4.3.2.1.in-addr.arpa and places the packet-encoded domain name into q.  

SEE ALSO

dns_domain(3), dns_ip4(3), dns_ip4_qualify(3), dns_mx(3), dns_packet(3), dns_random(3), dns_transmit(3), dns_txt(3)

http://cr.yp.to/djbdns/blurb/library.html


 

Index

NAME
SYSNOPSIS
DESCRIPTION
SEE ALSO

This document was created by man2html, using the manual pages.
Time: 21:45:10 GMT, April 16, 2011