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| -rw-r--r-- | src/bin/dhcp4/dhcp4o6.dox | 62 |
1 files changed, 62 insertions, 0 deletions
diff --git a/src/bin/dhcp4/dhcp4o6.dox b/src/bin/dhcp4/dhcp4o6.dox new file mode 100644 index 0000000..134a235 --- /dev/null +++ b/src/bin/dhcp4/dhcp4o6.dox @@ -0,0 +1,62 @@ +// Copyright (C) 2016 Internet Systems Consortium, Inc. ("ISC") +// +// This Source Code Form is subject to the terms of the Mozilla Public +// License, v. 2.0. If a copy of the MPL was not distributed with this +// file, You can obtain one at http://mozilla.org/MPL/2.0/. + +/** + @page dhcpv4o6Dhcp4 DHCPv4-over-DHCPv6 DHCPv4 Server Side + +Kea supports DHCPv4-over-DHCPv6 using cooperating DHCPv6 and DHCPv4 +servers. This section describes the DHCPv4 server side. For its +DHCPv6 counter-part, see @ref dhcpv4o6Dhcp6. + +@section Dhcp4to6Ipc DHCPv6-to-DHCPv4 Inter Process Communication + +The @c Dhcp4to6Ipc class is derived from the base @c Dhcp4o6IpcBase as +a singleton class (by the static @ref isc::dhcp::Dhcp4to6Ipc::instance +function). @ref isc::dhcp::Dhcp4to6Ipc::open is called to open IPC +UDP sockets and to register @ref isc::dhcp::Dhcp4to6Ipc::handler on +external sockets on the @c IfaceMgr. + +@section dhcp4to6Receive DHCPv4-over-DHCPv6 Packet Processing + +DHCPv6 DHCPv4-QUERY messages are forwarded by the DHCPv6 server on the IPC. +The interface manager (@c IfaceMgr) using the external socket mechanism +invokes @ref isc::dhcp::Dhcp4to6Ipc::handler, the packet is received using +(inherited) @ref isc::dhcp::Dhcp4o6IpcBase::receive which decodes and strips +the ISC Vendor option. + +The handler verifies there is one and only one DHCPv4-Message option +and extracts it. @ref isc::dhcp::Dhcpv4Srv::processPacket processes +the DHCPv4 query as a @c Pkt4o6 instance and builds the +DHCPv4-over-DHCPv6 response. +Registered callouts for "buffer4_send" are called (@ref +dhcpv4HooksBuffer4Send, note all the other DHCPv4 hook points are +served during the standard processing). The response is sent back +to the DHCPv6 server on the IPC. + +@section dhcp4to6Specific Modified DHCPv4 Routines + +For a @c Pkt4o6 query the @ref isc::dhcp::Dhcpv4Exchange::initResponse +performs some extra steps (@ref isc::dhcp::Dhcpv4Exchange::initResponse4o6): +the DHCPv6 response is built and the response member is reset to +a @c Pkt4o6 instance with DHCPv4 and DHCPv6 parts. + +The subnet selection (@ref isc::dhcp::Dhcpv4Srv::selectSubnet) is specialized +for @c Pkt4o6 queries (@ref isc::dhcp::Dhcpv4Srv::selectSubnet4o6): +the subnet selector class (@c SubnetSelector) is filled using DHCPv4 and +DHCPv6 information and the @ref isc::dhcp::CfgSubnets4::selectSubnet4o6 +function is called (instead of @ref isc::dhcp::CfgSubnets4::selectSubnet). + +In @ref isc::dhcp::Dhcpv4Srv::adjustIfaceData for @c Pkt4o6 queries +the local address is set to the incoming interface assigned address +(same case than for a broadcast local address). + +In @ref isc::dhcp::Dhcpv4Srv::adjustRemoteAddr for @c Pkt4o6 queries the +remote address is set to the query one (which is in fact an IPv6 address). + +In @ref isc::dhcp::Dhcpv4Srv::acceptDirectRequest @c Pkt4o6 queries are +accepted (they are considered as being relayed). + +*/ |