Commit 5a695278 authored by Mark Andrews's avatar Mark Andrews
Browse files

Added "Overview".

parent 19d365e4
......@@ -4,7 +4,26 @@
<TITLE>Adding new RDATA type</TITLE>
</HEAD>
<BODY>
<H1>Adding new RDATA types</H1>
<H2>Overview</H2>
The dns rdata routines (<CODE>dns_rdata_fromtext()</CODE>,
<CODE>dns_rdata_totext()</CODE>, <CODE>dns_rdata_fromwire()</CODE>,
<CODE>dns_rdata_towire()</CODE> <CODE>dns_rdata_fromstruct()</CODE>,
<CODE>dns_rdata_tostruct()</CODE> and <CODE>dns_rdata_compare()</CODE>)
are designed to provide a single set of routines
for encoding, decoding and comparing dns data preventing the problems that
occurred in BIND 8.x and earlier where there were multiple places in the
code base that
decoded wire format to internal format or compared rdata sometimes with
subtly different behaviour (bugs) or didn't support a particular type leading
to internal inconsistancy.
<P>
Each of these generic routines calls type specific routines that provide
the type specific details.
<P>
From time to time new types are defined and it is necessary to add these types
into the existing structure.
This document is written to provide instruction on how to do this.
<H2>Adding new RDATA types</H2>
Adding a new rdata type requires determining if the new rdata type is class
specific or generic.
......@@ -91,6 +110,11 @@ Class and type names must be from the following alphabet and less that 11
characters in length or otherwise they will be ignored.
Permissible alphabet: a to z, 0 to 9 and dash (-).
Dash is mapped to underscore (_) for the C function names below.
<H2>Internal Format</H2>
The internal format choosen is DNS wire format without any compression being
applied to domain names in the rdata.
<H2>Convert from text format to internal format</H2>
The functions to convert from text format has the following call formats and
is declared as follows for class generic functions.
......
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