/*
             LUFA Library
     Copyright (C) Dean Camera, 2017.

  dean [at] fourwalledcubicle [dot] com
           www.lufa-lib.org
*/

/*
  Copyright 2017  Dean Camera (dean [at] fourwalledcubicle [dot] com)

  Permission to use, copy, modify, distribute, and sell this
  software and its documentation for any purpose is hereby granted
  without fee, provided that the above copyright notice appear in
  all copies and that both that the copyright notice and this
  permission notice and warranty disclaimer appear in supporting
  documentation, and that the name of the author not be used in
  advertising or publicity pertaining to distribution of the
  software without specific, written prior permission.

  The author disclaims all warranties with regard to this
  software, including all implied warranties of merchantability
  and fitness.  In no event shall the author be liable for any
  special, indirect or consequential damages or any damages
  whatsoever resulting from loss of use, data or profits, whether
  in an action of contract, negligence or other tortious action,
  arising out of or in connection with the use or performance of
  this software.
*/

/** \file
 *
 *  DHCP Client Application. When connected to the uIP stack, this will retrieve IP configuration settings from the
 *  DHCP server on the network.
 */

#define  INCLUDE_FROM_DHCPCLIENTAPP_C
#include "DHCPClientApp.h"

#if defined(ENABLE_DHCP_CLIENT) || defined(__DOXYGEN__)

/** Initialization function for the DHCP client. */
void DHCPClientApp_Init(void)
{
	/* Create a new UDP connection to the DHCP server port for the DHCP solicitation */
	struct uip_udp_conn* Connection = uip_udp_new(&uip_broadcast_addr, HTONS(DHCP_SERVER_PORT));

	/* If the connection was successfully created, bind it to the local DHCP client port */
	if (Connection != NULL)
	{
		uip_udp_appstate_t* const AppState = &Connection->appstate;
		uip_udp_bind(Connection, HTONS(DHCP_CLIENT_PORT));

		/* Set the initial client state */
		AppState->DHCPClient.CurrentState = DHCP_STATE_SendDiscover;

		/* Set timeout period to half a second for a DHCP server to respond */
		timer_set(&AppState->DHCPClient.Timeout, CLOCK_SECOND / 2);
	}
}

/** uIP stack application callback for the DHCP client. This function must be called each time the TCP/IP stack
 *  needs a UDP packet to be processed.
 */
void DHCPClientApp_Callback(void)
{
	uip_udp_appstate_t* const AppState    = &uip_udp_conn->appstate;
	DHCP_Header_t*      const AppData     = (DHCP_Header_t*)uip_appdata;
	uint16_t                  AppDataSize = 0;

	switch (AppState->DHCPClient.CurrentState)
	{
		case DHCP_STATE_SendDiscover:
			/* Clear all DHCP settings, reset client IP address */
			memset(&AppState->DHCPClient.DHCPOffer_Data, 0x00, sizeof(AppState->DHCPClient.DHCPOffer_Data));
			uip_sethostaddr((uip_ipaddr_t*)&AppState->DHCPClient.DHCPOffer_Data.AllocatedIP);

			/* Fill out the DHCP response header */
			AppDataSize += DHCPClientApp_FillDHCPHeader(AppData, DHCP_DISCOVER, AppState);

			/* Add the required DHCP options list to the packet */
			uint8_t RequiredOptionList[] = {DHCP_OPTION_SUBNET_MASK, DHCP_OPTION_ROUTER, DHCP_OPTION_DNS_SERVER};
			AppDataSize += DHCPCommon_SetOption(AppData->Options, DHCP_OPTION_REQ_LIST, sizeof(RequiredOptionList),
			                                    RequiredOptionList);

			/* Send the DHCP DISCOVER packet */
			uip_udp_send(AppDataSize);

			/* Reset the timeout timer, progress to next state */
			timer_reset(&AppState->DHCPClient.Timeout);
			AppState->DHCPClient.CurrentState = DHCP_STATE_WaitForOffer;

			break;
		case DHCP_STATE_WaitForOffer:
			if (!(uip_newdata()))
			{
				/* Check if the DHCP timeout period has expired while waiting for a response */
				if (timer_expired(&AppState->DHCPClient.Timeout))
				  AppState->DHCPClient.CurrentState = DHCP_STATE_SendDiscover;

				break;
			}

			uint8_t OfferResponse_MessageType;
			if ((AppData->TransactionID == DHCP_TRANSACTION_ID) &&
			    DHCPCommon_GetOption(AppData->Options, DHCP_OPTION_MSG_TYPE, &OfferResponse_MessageType) &&
			    (OfferResponse_MessageType == DHCP_OFFER))
			{
				/* Received a DHCP offer for an IP address, copy over values for later request */
				memcpy(&AppState->DHCPClient.DHCPOffer_Data.AllocatedIP, &AppData->YourIP, sizeof(uip_ipaddr_t));
				DHCPCommon_GetOption(AppData->Options, DHCP_OPTION_SUBNET_MASK, &AppState->DHCPClient.DHCPOffer_Data.Netmask);
				DHCPCommon_GetOption(AppData->Options, DHCP_OPTION_ROUTER,      &AppState->DHCPClient.DHCPOffer_Data.GatewayIP);
				DHCPCommon_GetOption(AppData->Options, DHCP_OPTION_SERVER_ID,   &AppState->DHCPClient.DHCPOffer_Data.ServerIP);

				timer_reset(&AppState->DHCPClient.Timeout);
				AppState->DHCPClient.CurrentState = DHCP_STATE_SendRequest;
			}

			break;
		case DHCP_STATE_SendRequest:
			/* Fill out the DHCP response header */
			AppDataSize += DHCPClientApp_FillDHCPHeader(AppData, DHCP_REQUEST, AppState);

			/* Add the DHCP REQUESTED IP ADDRESS option to the packet */
			AppDataSize += DHCPCommon_SetOption(AppData->Options, DHCP_OPTION_REQ_IPADDR, sizeof(uip_ipaddr_t),
			                                    &AppState->DHCPClient.DHCPOffer_Data.AllocatedIP);

			/* Add the DHCP SERVER IP ADDRESS option to the packet */
			AppDataSize += DHCPCommon_SetOption(AppData->Options, DHCP_OPTION_SERVER_ID, sizeof(uip_ipaddr_t),
			                                    &AppState->DHCPClient.DHCPOffer_Data.ServerIP);

			/* Send the DHCP REQUEST packet */
			uip_udp_send(AppDataSize);

			/* Reset the timeout timer, progress to next state */
			timer_reset(&AppState->DHCPClient.Timeout);
			AppState->DHCPClient.CurrentState = DHCP_STATE_WaitForACK;

			break;
		case DHCP_STATE_WaitForACK:
			if (!(uip_newdata()))
			{
				/* Check if the DHCP timeout period has expired while waiting for a response */
				if (timer_expired(&AppState->DHCPClient.Timeout))
				  AppState->DHCPClient.CurrentState = DHCP_STATE_SendDiscover;

				break;
			}

			uint8_t RequestResponse_MessageType;
			if ((AppData->TransactionID == DHCP_TRANSACTION_ID) &&
			    DHCPCommon_GetOption(AppData->Options, DHCP_OPTION_MSG_TYPE, &RequestResponse_MessageType) &&
			    (RequestResponse_MessageType == DHCP_ACK))
			{
				/* Set the new network parameters from the DHCP server */
				uip_sethostaddr((uip_ipaddr_t*)&AppState->DHCPClient.DHCPOffer_Data.AllocatedIP);
				uip_setnetmask((uip_ipaddr_t*)&AppState->DHCPClient.DHCPOffer_Data.Netmask);
				uip_setdraddr((uip_ipaddr_t*)&AppState->DHCPClient.DHCPOffer_Data.GatewayIP);

				AppState->DHCPClient.CurrentState = DHCP_STATE_AddressLeased;
			}

			break;
	}
}

/** Fills the DHCP packet response with the appropriate BOOTP header for DHCP. This fills out all the required
 *  fields, leaving only the additional DHCP options to be added to the packet before it is sent to the DHCP server.
 *
 *  \param[out] DHCPHeader       Location in the packet buffer where the BOOTP header should be written to
 *  \param[in]  DHCPMessageType  DHCP Message type, such as DHCP_DISCOVER
 *  \param[in]  AppState         Application state of the current UDP connection
 *
 *  \return Size in bytes of the created DHCP packet
 */
static uint16_t DHCPClientApp_FillDHCPHeader(DHCP_Header_t* const DHCPHeader,
                                             const uint8_t DHCPMessageType,
                                             uip_udp_appstate_t* const AppState)
{
	/* Erase existing packet data so that we start will all 0x00 DHCP header data */
 	memset(DHCPHeader, 0, sizeof(DHCP_Header_t));

	/* Fill out the DHCP packet header */
	DHCPHeader->Operation             = DHCP_OP_BOOTREQUEST;
	DHCPHeader->HardwareType          = DHCP_HTYPE_ETHERNET;
	DHCPHeader->HardwareAddressLength = sizeof(MACAddress);
	DHCPHeader->Hops                  = 0;
	DHCPHeader->TransactionID         = DHCP_TRANSACTION_ID;
	DHCPHeader->ElapsedSeconds        = 0;
	DHCPHeader->Flags                 = HTONS(BOOTP_BROADCAST);
	memcpy(&DHCPHeader->ClientIP,     &uip_hostaddr,        sizeof(uip_ipaddr_t));
	memcpy(&DHCPHeader->YourIP,       &AppState->DHCPClient.DHCPOffer_Data.AllocatedIP, sizeof(uip_ipaddr_t));
	memcpy(&DHCPHeader->NextServerIP, &AppState->DHCPClient.DHCPOffer_Data.ServerIP,    sizeof(uip_ipaddr_t));
	memcpy(&DHCPHeader->ClientHardwareAddress, &MACAddress, sizeof(struct uip_eth_addr));
	DHCPHeader->Cookie                = DHCP_MAGIC_COOKIE;

	/* Add a DHCP message type and terminator options to the start of the DHCP options field */
	DHCPHeader->Options[0]            = DHCP_OPTION_MSG_TYPE;
	DHCPHeader->Options[1]            = 1;
	DHCPHeader->Options[2]            = DHCPMessageType;
	DHCPHeader->Options[3]            = DHCP_OPTION_END;

	/* Calculate the total number of bytes added to the outgoing packet */
	return (sizeof(DHCP_Header_t) + 4);
}

#endif

