/*
 * FreeRTOS+TCP <DEVELOPMENT BRANCH>
 * Copyright (C) 2022 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
 *
 * SPDX-License-Identifier: MIT
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * https://www.FreeRTOS.org
 * https://github.com/FreeRTOS
 */

#ifndef FREERTOS_IPV4_PRIVATE_H
#define FREERTOS_IPV4_PRIVATE_H

#include "FreeRTOS_IP_Private.h"

/* *INDENT-OFF* */
#ifdef __cplusplus
    extern "C" {
#endif
/* *INDENT-ON* */

/* The maximum UDP payload length. */
#define ipMAX_UDP_PAYLOAD_LENGTH        ( ( ipconfigNETWORK_MTU - ipSIZE_OF_IPv4_HEADER ) - ipSIZE_OF_UDP_HEADER )

#define TCP_PACKET_SIZE                 ( sizeof( TCPPacket_t ) )

/* The offset into an IP packet into which the IP data (payload) starts. */
#define ipIP_PAYLOAD_OFFSET             ( sizeof( IPPacket_t ) )
/* The offset into a UDP packet at which the UDP data (payload) starts. */
#define ipUDP_PAYLOAD_OFFSET_IPv4       ( sizeof( UDPPacket_t ) )
/* The value of 'ipUDP_PAYLOAD_IP_TYPE_OFFSET' is 8 + 40 = 48 bytes. */
#define ipUDP_PAYLOAD_IP_TYPE_OFFSET    ( sizeof( UDPHeader_t ) + sizeof( IPHeader_IPv6_t ) )

/* ipIP_TYPE_OFFSET is involved in some sorcery. pxUDPPayloadBuffer_to_NetworkBuffer() must be able to convert
 * a payload pointer ( like for example a pointer to the DNS payload of a packet ) back to a NetworkBufferDescriptor_t.
 * This must work for both IPv4 and IPv6 packets. The pointer conversion is done by subtracting a constant from the payload pointer.
 * For IPv6, this magic number is ( sizeof( UDPHeader_t ) + sizeof( IPHeader_IPv6_t ) ) which equals 48 bytes.
 * If however we use that same constant for an IPv4 packet, we end up somewhere in front of the Ethernet header.
 * In order to accommodate that, the Ethernet frame buffer gets allocated a bit larger than needed.
 * For IPv4 frames, prvProcessIPPacket() stores the version header field at a negative offset, a few bytes before the start
 * of the Ethernet header. That IPv4 version field MUST be stored the same distance from the payload as in IPv6.
 * ipIP_TYPE_OFFSET must be equal to: sizeof( UDPHeader_t ) + sizeof( IPHeader_IPv6_t ) - ( sizeof( UDPPacket_t )
 * In most situations, ipIP_TYPE_OFFSET will end up being equal to 6. If the Ethernet header is enlarged to include VLAN
 * tag support, ipIP_TYPE_OFFSET will shrink to 2. With the current design, the Ethernet header cannot be expanded to contain
 * more than one VLAN tag or ipIP_TYPE_OFFSET will become less than zero. ipIP_TYPE_OFFSET should never be allowed to be <= 0
 * or storing of the IPv4 version byte will overwrite the Ethernet header of the frame.
 */
#define ipIP_TYPE_OFFSET                ( ( int32_t ) sizeof( UDPHeader_t ) + ( int32_t ) sizeof( IPHeader_IPv6_t ) - ( int32_t ) sizeof( UDPPacket_t ) )

#include "pack_struct_start.h"
struct xIP_HEADER
{
    uint8_t ucVersionHeaderLength;        /**< The version field + internet header length 0 + 1 =  1 */
    uint8_t ucDifferentiatedServicesCode; /**< Differentiated services code point + ECN   1 + 1 =  2 */
    uint16_t usLength;                    /**< Entire Packet size, ex. Ethernet header.   2 + 2 =  4 */
    uint16_t usIdentification;            /**< Identification field                       4 + 2 =  6 */
    uint16_t usFragmentOffset;            /**< Fragment flags and fragment offset         6 + 2 =  8 */
    uint8_t ucTimeToLive;                 /**< Time to live field                         8 + 1 =  9 */
    uint8_t ucProtocol;                   /**< Protocol used in the IP-datagram           9 + 1 = 10 */
    uint16_t usHeaderChecksum;            /**< Checksum of the IP-header                 10 + 2 = 12 */
    uint32_t ulSourceIPAddress;           /**< IP address of the source                  12 + 4 = 16 */
    uint32_t ulDestinationIPAddress;      /**< IP address of the destination             16 + 4 = 20 */
}
#include "pack_struct_end.h"
typedef struct xIP_HEADER IPHeader_t;

/*-----------------------------------------------------------*/
/* Nested protocol packets.                                  */
/*-----------------------------------------------------------*/

#include "pack_struct_start.h"
struct xIP_PACKET
{
    EthernetHeader_t xEthernetHeader;
    IPHeader_t xIPHeader;
}
#include "pack_struct_end.h"
typedef struct xIP_PACKET IPPacket_t;

#include "pack_struct_start.h"
struct xICMP_PACKET
{
    EthernetHeader_t xEthernetHeader; /**< The Ethernet header of an ICMP packet. */
    IPHeader_t xIPHeader;             /**< The IP header of an ICMP packet. */
    ICMPHeader_t xICMPHeader;         /**< The ICMP header of an ICMP packet. */
}
#include "pack_struct_end.h"
typedef struct xICMP_PACKET ICMPPacket_t;


#include "pack_struct_start.h"
struct xUDP_PACKET
{
    EthernetHeader_t xEthernetHeader; /**< UDP-Packet ethernet header  0 + 14 = 14 */
    IPHeader_t xIPHeader;             /**< UDP-Packet IP header        14 + 20 = 34 */
    UDPHeader_t xUDPHeader;           /**< UDP-Packet UDP header       34 +  8 = 42 */
}
#include "pack_struct_end.h"
typedef struct xUDP_PACKET UDPPacket_t;

#include "pack_struct_start.h"
struct xTCP_PACKET
{
    EthernetHeader_t xEthernetHeader; /**< The ethernet header  0 + 14 = 14 */
    IPHeader_t xIPHeader;             /**< The IP header        14 + 20 = 34 */
    TCPHeader_t xTCPHeader;           /**< The TCP header       34 + 32 = 66 */
}
#include "pack_struct_end.h"
typedef struct xTCP_PACKET TCPPacket_t;

/* *INDENT-OFF* */
#ifdef __cplusplus
    } /* extern "C" */
#endif
/* *INDENT-ON* */

#endif /* FREERTOS_IP_PRIVATE_H */