#!/usr/bin/env less


SRV library version 1.0
=======================

(c) 2001 Rick van Rein

This library makes it easy to connect to a server for a specified Internet
protocol under a specified domain, either as a networking client or server.

Connection-making is extremely reliable, and implements load balancing and
fallback (prioritised) servers as defined in SRV records. There is even a
fallback program to old-style (A and CNAME) records if there are no SRV
records for the requested domain. This ensures backward compatibility with
older domains.

This code implements RFC 2782, "A DNS RR for specifying the location of
services (DNS SRV)" by Gulbrandsen, Vixie and Esibov. The fallback to
old-style (A and CNAME) records are a non-interfering extension to the RFC.

This code is available under a FreeBSD styled license (twisted to make it
fall under my company, and not the Berkeley uni of course).  This makes
it explicitly possible to include this code in commercial applications without
providing the code.  In order of my preference though, your style would be
 1. Write SRV-aware code and publish it
 2. Write SRV-aware code
 3. Do the blunt old IN A thing


Differences with prior practices
--------------------------------

 * This library uses SRV records when they are available. There is a fallback
   program to old-style records.

 * The level is a lot higher than the abstract socket programming interface.
   You simply receive an already-connected socket for a client, or an
   already-bound-and-listening socket for a server.

 * Connections are made very failsafe, as more information is available to
   the library than the common socket routines ever get.

 * If multiple IP numbers and/or ports exist under a name, they are all tried
   until one accepts the requested connection.


What this package contains
--------------------------

doc    -> a website on SRV records, and why, and how, and...
netana -> manually decomposed query, as a DIG query and as annotated hexdump
src    -> the source code, with include/... as include directory section.

The stuff that currently works is in src.  Build it, perhaps after twisting the
Makefile a bit, and install it to have a libsrv running.  Then, look at the
other modules under the libsrv CVS; it contains apps based on the library.


Enjoy,

Rick van Rein,
rick@vanrein.org