====== Poslib DNS library ======

Poslib is the C++ library for applications using the Domain Name System that is used by all Posadis tools, including the [[Posadis DNS]] server and the [[Zoneedit]] and [[Dnsquery]] tools. It consists of a library for creating client applications using DNS, and a server library for DNS servers.

For documentation on the stable series of Poslib, see [[Documentation]]. For documentation on the development series, see the [[poslib:index]]. To download the latest version, go to the [[Download]] page.

===== Features and benefits =====

^Feature 	^Benefit^
|Portable 	|Write your program once, and build it under many Unix variants, Linux, Windows, Mac OS X and others|
|Client resolver 	|Write programs that send DNS messages to servers, including normal queries, zone tranfers, DNS Update messages, and so on|
|Resource Record handling 	|Read, write and interpret many different types of Resource records (over 20 types supported)|
|Master file parser 	|Write programs that support the standard DNS master file format|
|Server library 	|Easily write DNS server programs without having to worry about any low-level transport details|

===== Examples =====

To see Poslib at work, you can see some simple examples Poslib ships with, or take a look at the source code of real-life applications such as the Posadis DNS server or the Zoneedit tool.

Allright, a quick example:
<code cpp>#include <stdio.h>
#include <poslib/poslib.h>

int main(int argc, char **argv) {
  _addr addr;
  DnsMessage *q = NULL, *a = NULL;
  pos_cliresolver res;
  a_record ip;
 
  try {
    txt_to_addr(&addr, "127.0.0.1");             // server to query
    q = create_query("acdam.net", DNS_TYPE_A);   // query message: A record for acdam.net
 
    res.query(q, a, &addr);                      // send query
    ip = get_a_record(a);                        // get answer record from query
    printf("%s has address %d.%d.%d.%d\n",       // print out answer:
           q->questions.begin()->QNAME.tocstr(), // queried domain name
           ip.address[0], ip.address[1],         // IP address
           ip.address[2], ip.address[3]);
    } catch (PException p) {                     // catch any poslib errors
      printf("*** Fatal error: %s\n", p.message);// print error message
    }
  }
 
  if (q) delete q; if (a) delete a;
  return 0;
}</code>