FreeRTOS-Plus-TCP/source/FreeRTOS_TCP_State_Handling_IPV4.c

/*
 * 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.
 *
 * http://aws.amazon.com/freertos
 * http://www.FreeRTOS.org
 */

/**
 * @file FreeRTOS_TCP_State_Handling_IPV4.c
 * @brief Module which handles the TCP protocol state transition for FreeRTOS+TCP.
 *
 * Endianness: in this module all ports and IP addresses are stored in
 * host byte-order, except fields in the IP-packets
 */

/* Standard includes. */
#include <stdint.h>
#include <stdio.h>

/* FreeRTOS includes. */
#include "FreeRTOS.h"
#include "task.h"
#include "queue.h"
#include "semphr.h"

/* FreeRTOS+TCP includes. */
#include "FreeRTOS_IP.h"
#include "FreeRTOS_Sockets.h"
#include "FreeRTOS_IP_Private.h"
#include "FreeRTOS_UDP_IP.h"
#include "FreeRTOS_DHCP.h"
#include "NetworkInterface.h"
#include "NetworkBufferManagement.h"
#include "FreeRTOS_ARP.h"

#include "FreeRTOS_TCP_Reception.h"
#include "FreeRTOS_TCP_Transmission.h"
#include "FreeRTOS_TCP_State_Handling.h"
#include "FreeRTOS_TCP_Utils.h"

/* *INDENT-OFF* */
#if( ipconfigUSE_IPv4 != 0 )
/* *INDENT-ON* */

/* Just make sure the contents doesn't get compiled if TCP is not enabled. */
#if ipconfigUSE_TCP == 1

/**
 * @brief Handle 'listen' event on the given socket.
 *
 * @param[in] pxSocket: The socket on which the listen occurred.
 * @param[in] pxNetworkBuffer: The network buffer carrying the packet.
 *
 * @return If a new socket/duplicate socket is created, then the pointer to
 *         that socket is returned or else, a NULL pointer is returned.
 */
    FreeRTOS_Socket_t * prvHandleListen_IPV4( FreeRTOS_Socket_t * pxSocket,
                                              NetworkBufferDescriptor_t * pxNetworkBuffer )
    {
        /* Map the ethernet buffer onto a TCPPacket_t struct for easy access to the fields. */

        /* MISRA Ref 11.3.1 [Misaligned access] */
/* More details at: https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/blob/main/MISRA.md#rule-113 */
        /* coverity[misra_c_2012_rule_11_3_violation] */
        const TCPPacket_t * pxTCPPacket = ( ( const TCPPacket_t * ) pxNetworkBuffer->pucEthernetBuffer );
        FreeRTOS_Socket_t * pxReturn = NULL;
        uint32_t ulInitialSequenceNumber;

        /* Silently discard a SYN packet which was not specifically sent for this node. */
        if( pxTCPPacket->xIPHeader.ulDestinationIPAddress == *ipLOCAL_IP_ADDRESS_POINTER )
        {
            /* Assume that a new Initial Sequence Number will be required. Request
             * it now in order to fail out if necessary. */
            ulInitialSequenceNumber = ulApplicationGetNextSequenceNumber( *ipLOCAL_IP_ADDRESS_POINTER,
                                                                          pxSocket->usLocalPort,
                                                                          pxTCPPacket->xIPHeader.ulSourceIPAddress,
                                                                          pxTCPPacket->xTCPHeader.usSourcePort );
        }
        else
        {
            /* Set the sequence number to 0 to avoid further processing. */
            ulInitialSequenceNumber = 0U;
        }

        /* A pure SYN (without ACK) has come in, create a new socket to answer
         * it. */
        if( ulInitialSequenceNumber != 0U )
        {
            if( pxSocket->u.xTCP.bits.bReuseSocket != pdFALSE_UNSIGNED )
            {
                /* The flag bReuseSocket indicates that the same instance of the
                 * listening socket should be used for the connection. */
                pxReturn = pxSocket;
                pxSocket->u.xTCP.bits.bPassQueued = pdTRUE_UNSIGNED;
                pxSocket->u.xTCP.pxPeerSocket = pxSocket;
            }
            else
            {
                /* The socket does not have the bReuseSocket flag set meaning create a
                 * new socket when a connection comes in. */
                pxReturn = NULL;

                if( pxSocket->u.xTCP.usChildCount >= pxSocket->u.xTCP.usBacklog )
                {
                    FreeRTOS_printf( ( "Check: Socket %u already has %u / %u child%s\n",
                                       pxSocket->usLocalPort,
                                       pxSocket->u.xTCP.usChildCount,
                                       pxSocket->u.xTCP.usBacklog,
                                       ( pxSocket->u.xTCP.usChildCount == 1U ) ? "" : "ren" ) );
                    ( void ) prvTCPSendReset( pxNetworkBuffer );
                }
                else
                {
                    FreeRTOS_Socket_t * pxNewSocket = ( FreeRTOS_Socket_t * )
                                                      FreeRTOS_socket( FREERTOS_AF_INET, FREERTOS_SOCK_STREAM, FREERTOS_IPPROTO_TCP );

                    /* MISRA Ref 11.4.1 [Socket error and integer to pointer conversion] */
                    /* More details at: https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/blob/main/MISRA.md#rule-114 */
                    /* coverity[misra_c_2012_rule_11_4_violation] */
                    if( ( pxNewSocket == NULL ) || ( pxNewSocket == FREERTOS_INVALID_SOCKET ) )
                    {
                        FreeRTOS_debug_printf( ( "TCP: Listen: new socket failed\n" ) );
                        ( void ) prvTCPSendReset( pxNetworkBuffer );
                    }
                    else if( prvTCPSocketCopy( pxNewSocket, pxSocket ) != pdFALSE )
                    {
                        /* The socket will be connected immediately, no time for the
                         * owner to setsockopt's, therefore copy properties of the server
                         * socket to the new socket.  Only the binding might fail (due to
                         * lack of resources). */
                        pxReturn = pxNewSocket;
                    }
                    else
                    {
                        /* Copying failed somehow. */
                    }
                }
            }
        }

        if( ( ulInitialSequenceNumber != 0U ) && ( pxReturn != NULL ) )
        {
            /* Map the byte stream onto the ProtocolHeaders_t for easy access to the fields. */

            /* MISRA Ref 11.3.1 [Misaligned access] */
            /* More details at: https://github.com/FreeRTOS/FreeRTOS-Plus-TCP/blob/main/MISRA.md#rule-113 */
            /* coverity[misra_c_2012_rule_11_3_violation] */
            const ProtocolHeaders_t * pxProtocolHeaders = ( ( const ProtocolHeaders_t * )
                                                            &( pxNetworkBuffer->pucEthernetBuffer[ ipSIZE_OF_ETH_HEADER + uxIPHeaderSizePacket( pxNetworkBuffer ) ] ) );

            if( pxNetworkBuffer->pxEndPoint != NULL )
            {
                pxReturn->pxEndPoint = pxNetworkBuffer->pxEndPoint;
            }

            configASSERT( pxReturn->pxEndPoint != NULL );

            pxReturn->bits.bIsIPv6 = pdFALSE_UNSIGNED;
            pxReturn->u.xTCP.usRemotePort = FreeRTOS_htons( pxTCPPacket->xTCPHeader.usSourcePort );
            pxReturn->u.xTCP.xRemoteIP.ulIP_IPv4 = FreeRTOS_htonl( pxTCPPacket->xIPHeader.ulSourceIPAddress );
            pxReturn->u.xTCP.xTCPWindow.ulOurSequenceNumber = ulInitialSequenceNumber;

            /* Here is the SYN action. */
            pxReturn->u.xTCP.xTCPWindow.rx.ulCurrentSequenceNumber = FreeRTOS_ntohl( pxProtocolHeaders->xTCPHeader.ulSequenceNumber );
            prvSocketSetMSS( pxReturn );

            prvTCPCreateWindow( pxReturn );

            vTCPStateChange( pxReturn, eSYN_FIRST );

            /* Make a copy of the header up to the TCP header.  It is needed later
             * on, whenever data must be sent to the peer. */
            ( void ) memcpy( ( void * ) pxReturn->u.xTCP.xPacket.u.ucLastPacket,
                             ( const void * ) pxNetworkBuffer->pucEthernetBuffer,
                             sizeof( pxReturn->u.xTCP.xPacket.u.ucLastPacket ) );
        }

        return pxReturn;
    }
    /*-----------------------------------------------------------*/

#endif /* ipconfigUSE_TCP == 1 */

/* *INDENT-OFF* */
#endif /* ( ipconfigUSE_IPv4 != 0 ) */
/* *INDENT-ON* */