/*
 * Copyright 2003-2007, Waldemar Kornewald <wkornew@gmx.net>
 * Distributed under the terms of the MIT License.
 */

#include "_KPPPMRUHandler.h"

#include <KPPPConfigurePacket.h>
#include <KPPPDevice.h>

#include <netinet/in.h>


static const uint8 kMRUType = 0x1;

typedef struct mru_item {
	uint8 type;
	uint8 length;
	uint16 MRU;
} _PACKED mru_item;

status_t ParseRequestedItem(mru_item *item, KPPPInterface& interface);


_KPPPMRUHandler::_KPPPMRUHandler(KPPPInterface& interface)
	: KPPPOptionHandler("MRU Handler", kMRUType, interface, NULL)
{
	Reset();
}


status_t
_KPPPMRUHandler::AddToRequest(KPPPConfigurePacket& request)
{
	if (!Interface().Device() || Interface().MRU() == 1500)
		return B_OK;
	
	// add MRU request
	mru_item item;
	item.type = kMRUType;
	item.length = 4;
	item.MRU = htons(fLocalMRU);
	return request.AddItem((ppp_configure_item*) &item) ? B_OK : B_ERROR;
}


status_t
_KPPPMRUHandler::ParseNak(const KPPPConfigurePacket& nak)
{
	mru_item *item = (mru_item*) nak.ItemWithType(kMRUType);
	if (!item || item->length != 4)
		return B_OK;
	
	uint16 MRU = ntohs(item->MRU);
	if (MRU < fLocalMRU)
		fLocalMRU = MRU;
	
	return B_OK;
}


status_t
_KPPPMRUHandler::ParseReject(const KPPPConfigurePacket& reject)
{
	if (reject.ItemWithType(kMRUType))
		return B_ERROR;
	
	return B_OK;
}


status_t
_KPPPMRUHandler::ParseAck(const KPPPConfigurePacket& ack)
{
	uint16 MRU = 1500;
	mru_item *item = (mru_item*) ack.ItemWithType(kMRUType);
	
	if (item)
		MRU = ntohs(item->MRU);
	
	if (MRU < Interface().MRU())
		fLocalMRU = MRU;
	
	return B_OK;
}


status_t
_KPPPMRUHandler::ParseRequest(const KPPPConfigurePacket& request,
	int32 index, KPPPConfigurePacket& nak, KPPPConfigurePacket& reject)
{
	if (index == reject.CountItems())
		return B_OK;
	
	return ParseRequestedItem((mru_item*) request.ItemAt(index), Interface());
	
	return B_OK;
}


status_t
_KPPPMRUHandler::SendingAck(const KPPPConfigurePacket& ack)
{
	return ParseRequestedItem((mru_item*) ack.ItemWithType(kMRUType), Interface());
}


// this function contains code shared by ParseRequest and SendingAck
status_t
ParseRequestedItem(mru_item *item, KPPPInterface& interface)
{
	uint16 MRU = 1500;
	
	if (item) {
		if (item->length != 4)
			return B_ERROR;
				// the request has a corrupted item
		
		MRU = ntohs(item->MRU);
	}
	
	if (MRU < interface.MRU())
		interface.SetMRU(MRU);
	
	return B_OK;
}


void
_KPPPMRUHandler::Reset()
{
	if (Interface().Device()) {
		fLocalMRU = Interface().Device()->MTU() - 2;
		Interface().SetMRU(fLocalMRU);
	} else {
		Interface().SetMRU(1500);
		fLocalMRU = 1500;
	}
}