Commit ff3ddd83 authored by Marcin Siodelski's avatar Marcin Siodelski
Browse files

[3180] Updated Developer Guide with an info about option parsing callbacks.

parent 0fcc98b0
......@@ -53,12 +53,14 @@
* - @subpage dhcpv4Session
* - @subpage dhcpv4ConfigParser
* - @subpage dhcpv4ConfigInherit
* - @subpage dhcpv4OptionsParse
* - @subpage dhcpv4Other
* - @subpage dhcp6
* - @subpage dhcpv6Session
* - @subpage dhcpv6ConfigParser
* - @subpage dhcpv6ConfigInherit
* - @subpage dhcpv6DDNSIntegration
* - @subpage dhcpv6OptionsParse
* - @subpage dhcpv6Other
* - @subpage libdhcp
* - @subpage libdhcpIntro
// Copyright (C) 2012 Internet Systems Consortium, Inc. ("ISC")
// Copyright (C) 2012-2013 Internet Systems Consortium, Inc. ("ISC")
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
......@@ -79,6 +79,11 @@ See \ref dhcpv6ConfigParser.
Configuration inheritance in DHCPv4 follows exactly the same logic as its DHCPv6
counterpart. See \ref dhcpv6ConfigInherit.
@section dhcpv4OptionsParse Custom functions to parse message options
The DHCPv4 server uses the same logic to supply custom callback function to
parse message option as DHCPv6 server implementation. See \ref dhcpv6OptionsParse.
@section dhcpv4Other Other DHCPv4 topics
For hooks API support in DHCPv4, see @ref dhcpv4Hooks.
......@@ -167,6 +167,29 @@ Once the configuration is implemented, these constants will be removed.
@todo Add section about setting up options and their definitions with bindctl.
@section dhcpv6OptionsParse Custom functions to parse message options
The DHCPv6 server implementation provides a generic support to define option
formats and set option values. A number of options formats have been defined
for standard options in libdhcp++. However, the formats for vendor specific
options are dynamically configured by the server's administrator and thus can't
be stored in libdhcp++. Such option formats are stored in the
@c isc::dhcp::CfgMgr. The libdhcp++ provides functions for recursive parsing
of options which may be encapsulated by other options up to the any level of
encapsulation but these functions are unaware of the option formats defined
in the @c isc::dhcp::CfgMgr because they belong to a different library.
Therefore, the generic functions @c isc::dhcp::LibDHCP::unpackOptions4 and
@c isc::dhcp::LibDHCP::unpackOptions6 are only useful to parse standard
options which definitions are provided in the libdhcp++. In order to overcome
this problem a callback mechanism has been implemented in @c Option and @c Pkt6
classes. By installing a callback function on the instance of the @c Pkt6 the
server may provide a custom implementation of the options parsing algorithm.
This callback function will take precedence over the @c LibDHCP::unpackOptions6
and @c LibDHCP::unpackOptions4 functions. With this approach, the callback is
implemented within the context of the server and it has access to all objects
which define its configuration (including dynamically created option
@section dhcpv6Other Other DHCPv6 topics
For hooks API support in DHCPv6, see @ref dhcpv6Hooks.
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