/*
 * Copyright 2003-2006, Waldemar Kornewald <wkornew@gmx.net>
 * Distributed under the terms of the MIT License.
 */

#include "Protocol.h"
#include <KPPPConfigurePacket.h>
#include <KPPPInterface.h>

#include <cstring>
#include <netinet/in.h>

#include <net_buffer.h>
#include <sys/sockio.h>

static const bigtime_t kPAPTimeout = 3000000;
	// 3 seconds

// PAPHandler
static const uint8 kAuthenticationType = 0x3;
static const char *kAuthenticatorTypeString = "Authenticator";

typedef struct authentication_item {
	uint8 type;
	uint8 length;
	uint16 protocolNumber;
} _PACKED authentication_item;


PAPHandler::PAPHandler(PAP& owner, KPPPInterface& interface)
	: KPPPOptionHandler("PAP", kAuthenticationType, interface, NULL),
	fOwner(owner)
{
}


status_t
PAPHandler::SendingAck(const KPPPConfigurePacket& ack)
{
	TRACE("%s::%s: We should activate PAP Protocol here\n", __FILE__, __func__);
	return KPPPOptionHandler::SendingAck(ack);
}


status_t
PAPHandler::AddToRequest(KPPPConfigurePacket& request)
{
	// only local authenticators send requests to peer
	if (Owner().Side() != PPP_PEER_SIDE)
		return B_OK;

	authentication_item item;
	item.type = kAuthenticationType;
	item.length = sizeof(item);
	item.protocolNumber = htons(PAP_PROTOCOL);

	request.AddItem((ppp_configure_item*) &item);

	return B_OK;
}


status_t
PAPHandler::ParseRequest(const KPPPConfigurePacket& request,
	int32 index, KPPPConfigurePacket& nak, KPPPConfigurePacket& reject)
{
	// only local authenticators handle requests from peer
	if (Owner().Side() != PPP_LOCAL_SIDE)
		return B_OK;

	// we merely check if the values are correct
	authentication_item *item = (authentication_item*) request.ItemAt(index);
	if (item->type != kAuthenticationType
			|| item->length != 4 || ntohs(item->protocolNumber) != PAP_PROTOCOL)
		return B_ERROR;

	return B_OK;
}


// PAP
PAP::PAP(KPPPInterface& interface, driver_parameter *settings)
	: KPPPProtocol("PAP", PPP_AUTHENTICATION_PHASE, PAP_PROTOCOL, PPP_PROTOCOL_LEVEL,
		AF_UNSPEC, 0, interface, settings, PPP_ALWAYS_ALLOWED,
		kAuthenticatorTypeString, new PAPHandler(*this, interface)),
	fState(INITIAL),
	fID(system_time() & 0xFF),
	fMaxRequest(3),
	fRequestID(0),
	fNextTimeout(0)
{
}


PAP::~PAP()
{
}


status_t
PAP::InitCheck() const
{
	if (Side() != PPP_LOCAL_SIDE && Side() != PPP_PEER_SIDE)
		return B_ERROR;

	return KPPPProtocol::InitCheck();
}


bool
PAP::Up()
{
	TRACE("PAP: Up() state=%d\n", State());

	switch (State()) {
		case INITIAL:
			if (Side() == PPP_LOCAL_SIDE) {
				NewState(REQ_SENT);
				InitializeRestartCount();
				SendRequest();
			} else if (Side() == PPP_PEER_SIDE) {
				NewState(WAITING_FOR_REQ);
				InitializeRestartCount();
				fNextTimeout = system_time() + kPAPTimeout;
			} else {
				UpFailedEvent();
				return false;
			}
		break;

		default:
			;
	}

	return true;
}


bool
PAP::Down()
{
	TRACE("PAP: Down() state=%d\n", State());

	switch (Interface().Phase()) {
		case PPP_DOWN_PHASE:
			// interface finished terminating
		case PPP_ESTABLISHED_PHASE:
			// terminate this NCP individually (block until we finished terminating)
			NewState(INITIAL);
			DownEvent();
		break;

/*		case PPP_TERMINATION_PHASE:
			// interface is terminating
		break;

		case PPP_ESTABLISHMENT_PHASE:
			// interface is reconfiguring
		break;
*/
		default:
			;
	}

	return true;
}


status_t
PAP::Send(net_buffer *packet, uint16 protocolNumber)
{
	// we do not encapsulate PAP packets
	TRACE("PAP: we should not send packet!\n");
	if (packet != NULL)
		gBufferModule->free(packet);
	return B_ERROR;
}


status_t
PAP::Receive(net_buffer *packet, uint16 protocolNumber)
{
	if (!packet)
		return B_ERROR;

	if (protocolNumber != PAP_PROTOCOL)
		return PPP_UNHANDLED;

	NetBufferHeaderReader<ppp_lcp_packet> bufferheader(packet);
	if (bufferheader.Status() != B_OK)
		return B_ERROR;
	ppp_lcp_packet &data = bufferheader.Data();

	// check if the packet is meant for us:
	// only peer authenticators handle requests
	if (data.code == PPP_CONFIGURE_REQUEST && Side() != PPP_PEER_SIDE)
		return PPP_UNHANDLED;
	// only local authenticators handle acks and naks
	if ((data.code == PPP_CONFIGURE_ACK || data.code == PPP_CONFIGURE_NAK)
			&& Side() != PPP_LOCAL_SIDE)
		return PPP_UNHANDLED;

	// remove padding
	int32 length = packet->size;
	length -= ntohs(data.length);

	if (ntohs(data.length) < 4)
		return B_ERROR;

	// packet is freed by event methods
	// code values are the same as for LCP (but very reduced)
	switch (data.code) {
		case PPP_CONFIGURE_REQUEST:
			RREvent(packet);
		break;

		case PPP_CONFIGURE_ACK:
			RAEvent(packet);
		break;

		case PPP_CONFIGURE_NAK:
			RNEvent(packet);
		break;

		default:
			return PPP_UNHANDLED;
	}

	return B_OK;
}


void
PAP::Pulse()
{
	if (fNextTimeout == 0 || fNextTimeout > system_time())
		return;
	fNextTimeout = 0;

	switch (State()) {
		case REQ_SENT:
		case WAITING_FOR_REQ:
			if (fRequestCounter <= 0)
				TOBadEvent();
			else
				TOGoodEvent();
		break;

		default:
			;
	}
}


uint8
PAP::NextID()
{
	return (uint8) atomic_add(&fID, 1);
}


void
PAP::NewState(pap_state next)
{
	TRACE("PAP: NewState(%d) state=%d\n", next, State());

	//  state changes
	if (State() == INITIAL && next != State()) {
		if (Side() == PPP_LOCAL_SIDE)
			Interface().StateMachine().LocalAuthenticationRequested();
		else if (Side() == PPP_PEER_SIDE)
			Interface().StateMachine().PeerAuthenticationRequested();

		UpStarted();
	} else if (State() == ACCEPTED && next != State())
		DownStarted();

	// maybe we do not need the timer anymore
	if (next == INITIAL || next == ACCEPTED)
		fNextTimeout = 0;

	fState = next;
}


void
PAP::TOGoodEvent()
{
	TRACE("PAP: TOGoodEvent() state=%d\n", State());

	switch (State()) {
		case REQ_SENT:
			SendRequest();
		break;

		case WAITING_FOR_REQ:
			fNextTimeout = system_time() + kPAPTimeout;
		break;

		default:
			;
	}
}


void
PAP::TOBadEvent()
{
	TRACE("PAP: TOBadEvent() state=%d\n", State());

	switch (State()) {
		case REQ_SENT:
		case WAITING_FOR_REQ:
			NewState(INITIAL);
			if (State() == REQ_SENT)
				Interface().StateMachine().LocalAuthenticationDenied(
					Interface().Username());
			else
				Interface().StateMachine().PeerAuthenticationDenied(
					Interface().Username());

			UpFailedEvent();
		break;

		default:
			;
	}
}


void
PAP::RREvent(net_buffer *packet)
{
	TRACE("PAP: RREvent() state=%d\n", State());

	NetBufferHeaderReader<ppp_lcp_packet> bufferheader(packet);
	if (bufferheader.Status() != B_OK)
		return;
	ppp_lcp_packet &request = bufferheader.Data();
	int32 length = ntohs(request.length);
	uint8 *data = request.data;
	uint8 *userLength = data;
	uint8 *passwordLength = data + 1 + data[0];

	// make sure the length values are all okay
	if (6 + *userLength + *passwordLength > length) {
		gBufferModule->free(packet);
		return;
	}

	char *peerUsername = (char*) userLength + 1,
		*peerPassword = (char*) passwordLength + 1;
	const char *username = Interface().Username(), *password = Interface().Password();

	if (*userLength == strlen(username) && *passwordLength == strlen(password)
			&& !strncmp(peerUsername, username, *userLength)
			&& !strncmp(peerPassword, password, *passwordLength)) {
		NewState(ACCEPTED);
		Interface().StateMachine().PeerAuthenticationAccepted(username);
		UpEvent();
		SendAck(packet);
	} else {
		NewState(INITIAL);
		Interface().StateMachine().PeerAuthenticationDenied(username);
		UpFailedEvent();
		SendNak(packet);
	}
}


void
PAP::RAEvent(net_buffer *packet)
{
	TRACE("PAP: RAEvent() state=%d\n", State());

	NetBufferHeaderReader<ppp_lcp_packet> bufferheader(packet);
	if (bufferheader.Status() != B_OK)
		return;
	ppp_lcp_packet &lcp_hdr = bufferheader.Data();
	if (fRequestID != lcp_hdr.id) {
		// this packet is not a reply to our request

		// TODO: log this event
		gBufferModule->free(packet);
		return;
	}

	switch (State()) {
		case REQ_SENT:
			NewState(ACCEPTED);
			Interface().StateMachine().LocalAuthenticationAccepted(
				Interface().Username());
			UpEvent();
		break;

		default:
			;
	}

	gBufferModule->free(packet);
}


void
PAP::RNEvent(net_buffer *packet)
{
	TRACE("PAP: RNEvent() state=%d\n", State());

	NetBufferHeaderReader<ppp_lcp_packet> bufferheader(packet);
	if (bufferheader.Status() != B_OK)
		return;
	ppp_lcp_packet &lcp_hdr = bufferheader.Data();
	if (fRequestID != lcp_hdr.id) {
		// this packet is not a reply to our request

		// TODO: log this event
		gBufferModule->free(packet);
		return;
	}

	switch (State()) {
		case REQ_SENT:
			NewState(INITIAL);
			Interface().StateMachine().LocalAuthenticationDenied(
				Interface().Username());
			UpFailedEvent();
		break;

		default:
			;
	}

	gBufferModule->free(packet);
}


void
PAP::InitializeRestartCount()
{
	fRequestCounter = fMaxRequest;
}


bool
PAP::SendRequest()
{
	TRACE("PAP: SendRequest() state=%d\n", State());

	--fRequestCounter;
	fNextTimeout = system_time() + kPAPTimeout;

	net_buffer *packet = gBufferModule->create(256);
	if (!packet)
		return false;

	ppp_lcp_packet *request;
	gBufferModule->append_size(packet, 1492, (void **)&request);

	const char *username = Interface().Username(), *password = Interface().Password();
	uint16 packcketLenth = 6 + strlen(username) + strlen(password);
		// 6 : lcp header 4 byte + username length 1 byte + password length 1 byte

	request->code = PPP_CONFIGURE_REQUEST;
	request->id = fRequestID = NextID();
	request->length = htons(packcketLenth);
	uint8 *data = request->data;
	data[0] = strlen(username);
	memcpy(data + 1, username, strlen(username));
	data[1 + data[0]] = strlen(password);
	memcpy(data + 2 + data[0], password, strlen(password));

	gBufferModule->trim(packet, packcketLenth);

	return Interface().Send(packet, PAP_PROTOCOL) == B_OK;
}


bool
PAP::SendAck(net_buffer *packet)
{
	TRACE("PAP: SendAck() state=%d\n", State());

	if (!packet)
		return false;

	NetBufferHeaderReader<ppp_lcp_packet> bufferheader(packet);
	if (bufferheader.Status() != B_OK)
		return false;
	ppp_lcp_packet &ack = bufferheader.Data();

	ack.code = PPP_CONFIGURE_ACK;
	ack.length = htons(5);
	ack.data[0] = 0;
	gBufferModule->trim(packet, 5);

	bufferheader.Sync();

	return Interface().Send(packet, PAP_PROTOCOL) == B_OK;
}


bool
PAP::SendNak(net_buffer *packet)
{
	ERROR("PAP: SendNak() state=%d\n", State());

	if (!packet)
		return false;

	NetBufferHeaderReader<ppp_lcp_packet> bufferheader(packet);
	if (bufferheader.Status() != B_OK)
		return false;
	ppp_lcp_packet &nak = bufferheader.Data();
	nak.code = PPP_CONFIGURE_NAK;
	nak.length = htons(5);
	nak.data[0] = 0;
	gBufferModule->trim(packet, 5);

	return Interface().Send(packet, PAP_PROTOCOL) == B_OK;
}