/*
* 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.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"
/* Just make sure the contents doesn't get compiled if TCP is not enabled. */
#if ipconfigUSE_TCP == 1
/*
* Called to handle the closure of a TCP connection.
*/
static BaseType_t prvTCPHandleFin( FreeRTOS_Socket_t * pxSocket,
const NetworkBufferDescriptor_t * pxNetworkBuffer );
/*
* Called from prvTCPHandleState() as long as the TCP status is eSYN_RECEIVED to
* eCONNECT_SYN.
*/
static BaseType_t prvHandleSynReceived( FreeRTOS_Socket_t * pxSocket,
const NetworkBufferDescriptor_t * pxNetworkBuffer,
uint32_t ulReceiveLength,
UBaseType_t uxOptionsLength );
/*
* Called from prvTCPHandleState() as long as the TCP status is eESTABLISHED.
*/
static BaseType_t prvHandleEstablished( FreeRTOS_Socket_t * pxSocket,
NetworkBufferDescriptor_t ** ppxNetworkBuffer,
uint32_t ulReceiveLength,
UBaseType_t uxOptionsLength );
/**
* @brief Check whether the socket is active or not.
*
* @param[in] eStatus The status of the socket.
*
* @return pdTRUE if the socket must be checked. Non-active sockets
* are waiting for user action, either connect() or close().
*/
BaseType_t prvTCPSocketIsActive( eIPTCPState_t eStatus )
{
BaseType_t xResult;
switch( eStatus )
{
case eCLOSED:
case eCLOSE_WAIT:
case eFIN_WAIT_2:
case eCLOSING:
case eTIME_WAIT:
xResult = pdFALSE;
break;
case eTCP_LISTEN:
case eCONNECT_SYN:
case eSYN_FIRST:
case eSYN_RECEIVED:
case eESTABLISHED:
case eFIN_WAIT_1:
case eLAST_ACK:
default:
xResult = pdTRUE;
break;
}
return xResult;
}
/*-----------------------------------------------------------*/
#if ( ipconfigTCP_HANG_PROTECTION == 1 )
/**
* @brief Some of the TCP states may only last a certain amount of time.
* This function checks if the socket is 'hanging', i.e. staying
* too long in the same state.
*
* @param[in] pxSocket the socket to be checked.
*
* @return pdFALSE if no checks are needed, pdTRUE if checks were done, or negative
* in case the socket has reached a critical time-out. The socket will go to
* the eCLOSE_WAIT state.
*/
BaseType_t prvTCPStatusAgeCheck( FreeRTOS_Socket_t * pxSocket )
{
BaseType_t xResult;
eIPTCPState_t eState = pxSocket->u.xTCP.eTCPState;
switch( eState )
{
case eESTABLISHED:
/* If the 'ipconfigTCP_KEEP_ALIVE' option is enabled, sockets in
* state ESTABLISHED can be protected using keep-alive messages. */
xResult = pdFALSE;
break;
case eCLOSED:
case eTCP_LISTEN:
case eCLOSE_WAIT:
/* These 3 states may last for ever, up to the owner. */
xResult = pdFALSE;
break;
case eCONNECT_SYN:
case eSYN_FIRST:
case eSYN_RECEIVED:
case eFIN_WAIT_1:
case eFIN_WAIT_2:
case eCLOSING:
case eLAST_ACK:
case eTIME_WAIT:
default:
/* All other (non-connected) states will get anti-hanging
* protection. */
xResult = pdTRUE;
break;
}
if( xResult != pdFALSE )
{
/* How much time has past since the last active moment which is
* defined as A) a state change or B) a packet has arrived. */
TickType_t xAge = xTaskGetTickCount() - pxSocket->u.xTCP.xLastActTime;
/* ipconfigTCP_HANG_PROTECTION_TIME is in units of seconds. */
if( xAge > ( ( TickType_t ) ipconfigTCP_HANG_PROTECTION_TIME * ( TickType_t ) configTICK_RATE_HZ ) )
{
#if ( ipconfigHAS_DEBUG_PRINTF == 1 )
{
FreeRTOS_debug_printf( ( "Inactive socket closed: port %u rem %xip:%u status %s\n",
pxSocket->usLocalPort,
( unsigned ) pxSocket->u.xTCP.xRemoteIP.ulIP_IPv4,
pxSocket->u.xTCP.usRemotePort,
FreeRTOS_GetTCPStateName( ( UBaseType_t ) pxSocket->u.xTCP.eTCPState ) ) );
}
#endif /* ipconfigHAS_DEBUG_PRINTF */
/* Move to eCLOSE_WAIT, user may close the socket. */
vTCPStateChange( pxSocket, eCLOSE_WAIT );
/* When 'bPassQueued' true, this socket is an orphan until it
* gets connected. */
if( pxSocket->u.xTCP.bits.bPassQueued != pdFALSE_UNSIGNED )
{
/* vTCPStateChange() has called vSocketCloseNextTime()
* in case the socket is not yet owned by the application.
* Return a negative value to inform the caller that
* the socket will be closed in the next cycle. */
xResult = -1;
}
}
}
return xResult;
}
/*-----------------------------------------------------------*/
#endif /* if ( ipconfigTCP_HANG_PROTECTION == 1 ) */
/**
* @brief prvTCPHandleFin() will be called to handle connection closure. The
* closure starts when either a FIN has been received and accepted,
* or when the socket has sent a FIN flag to the peer. Before being
* called, it has been checked that both reception and transmission
* are complete.
*
* @param[in] pxSocket Socket owning the the connection.
* @param[in] pxNetworkBuffer The network buffer carrying the TCP packet.
*
* @return Length of the packet to be sent.
*/
static BaseType_t prvTCPHandleFin( FreeRTOS_Socket_t * pxSocket,
const NetworkBufferDescriptor_t * pxNetworkBuffer )
{
/* Map the ethernet buffer onto the ProtocolHeader_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] */
ProtocolHeaders_t * pxProtocolHeaders = ( ( ProtocolHeaders_t * )
&( pxNetworkBuffer->pucEthernetBuffer[ ipSIZE_OF_ETH_HEADER + uxIPHeaderSizePacket( pxNetworkBuffer ) ] ) );
TCPHeader_t * pxTCPHeader = &( pxProtocolHeaders->xTCPHeader );
uint8_t ucIntermediateResult = 0, ucTCPFlags = pxTCPHeader->ucTCPFlags;
TCPWindow_t * pxTCPWindow = &pxSocket->u.xTCP.xTCPWindow;
BaseType_t xSendLength = 0;
uint32_t ulAckNr = FreeRTOS_ntohl( pxTCPHeader->ulAckNr );
if( ( ucTCPFlags & tcpTCP_FLAG_FIN ) != 0U )
{
pxTCPWindow->rx.ulCurrentSequenceNumber = pxTCPWindow->rx.ulFINSequenceNumber + 1U;
}
if( pxSocket->u.xTCP.bits.bFinSent == pdFALSE_UNSIGNED )
{
/* We haven't yet replied with a FIN, do so now. */
pxTCPWindow->tx.ulFINSequenceNumber = pxTCPWindow->tx.ulCurrentSequenceNumber;
pxSocket->u.xTCP.bits.bFinSent = pdTRUE_UNSIGNED;
}
else
{
/* We did send a FIN already, see if it's ACK'd. */
if( ulAckNr == ( pxTCPWindow->tx.ulFINSequenceNumber + 1U ) )
{
pxSocket->u.xTCP.bits.bFinAcked = pdTRUE_UNSIGNED;
}
}
if( pxSocket->u.xTCP.bits.bFinAcked == pdFALSE_UNSIGNED )
{
pxTCPWindow->tx.ulCurrentSequenceNumber = pxTCPWindow->tx.ulFINSequenceNumber;
pxTCPHeader->ucTCPFlags = ( uint8_t ) tcpTCP_FLAG_ACK | ( uint8_t ) tcpTCP_FLAG_FIN;
/* And wait for the final ACK. */
vTCPStateChange( pxSocket, eLAST_ACK );
}
else
{
/* Our FIN has been ACK'd, the outgoing sequence number is now fixed. */
pxTCPWindow->tx.ulCurrentSequenceNumber = pxTCPWindow->tx.ulFINSequenceNumber + 1U;
if( pxSocket->u.xTCP.bits.bFinRecv == pdFALSE_UNSIGNED )
{
/* We have sent out a FIN but the peer hasn't replied with a FIN
* yet. Do nothing for the moment. */
pxTCPHeader->ucTCPFlags = 0U;
}
else
{
if( pxSocket->u.xTCP.bits.bFinLast == pdFALSE_UNSIGNED )
{
/* This is the third of the three-way hand shake: the last
* ACK. */
pxTCPHeader->ucTCPFlags = tcpTCP_FLAG_ACK;
}
else
{
/* The other party started the closure, so we just wait for the
* last ACK. */
pxTCPHeader->ucTCPFlags = 0U;
}
/* And wait for the user to close this socket. */
vTCPStateChange( pxSocket, eCLOSE_WAIT );
}
}
pxTCPWindow->ulOurSequenceNumber = pxTCPWindow->tx.ulCurrentSequenceNumber;
if( pxTCPHeader->ucTCPFlags != 0U )
{
ucIntermediateResult = ( uint8_t ) ( uxIPHeaderSizeSocket( pxSocket ) + ipSIZE_OF_TCP_HEADER + pxTCPWindow->ucOptionLength );
xSendLength = ( BaseType_t ) ucIntermediateResult;
}
pxTCPHeader->ucTCPOffset = ( uint8_t ) ( ( ipSIZE_OF_TCP_HEADER + pxTCPWindow->ucOptionLength ) << 2 );
if( xTCPWindowLoggingLevel != 0 )
{
FreeRTOS_debug_printf( ( "TCP: send FIN+ACK (ack %u, cur/nxt %u/%u) ourSeqNr %u | Rx %u\n",
( unsigned ) ( ulAckNr - pxTCPWindow->tx.ulFirstSequenceNumber ),
( unsigned ) ( pxTCPWindow->tx.ulCurrentSequenceNumber - pxTCPWindow->tx.ulFirstSequenceNumber ),
( unsigned ) ( pxTCPWindow->ulNextTxSequenceNumber - pxTCPWindow->tx.ulFirstSequenceNumber ),
( unsigned ) ( pxTCPWindow->ulOurSequenceNumber - pxTCPWindow->tx.ulFirstSequenceNumber ),
( unsigned ) ( pxTCPWindow->rx.ulCurrentSequenceNumber - pxTCPWindow->rx.ulFirstSequenceNumber ) ) );
}
return xSendLength;
}
/*-----------------------------------------------------------*/
/**
* @brief prvHandleSynReceived(): called from prvTCPHandleState(). Called
* from the states: eSYN_RECEIVED and eCONNECT_SYN. If the flags
* received are correct, the socket will move to eESTABLISHED.
*
* @param[in] pxSocket The socket handling the connection.
* @param[in] pxNetworkBuffer The pointer to the network buffer carrying
* the packet.
* @param[in] ulReceiveLength Length in bytes of the data received.
* @param[in] uxOptionsLength Length of the TCP options in bytes.
*
* @return Length of the data to be sent.
*/
static BaseType_t prvHandleSynReceived( FreeRTOS_Socket_t * pxSocket,
const NetworkBufferDescriptor_t * pxNetworkBuffer,
uint32_t ulReceiveLength,
UBaseType_t uxOptionsLength )
{
/* Map the ethernet buffer onto the ProtocolHeader_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] */
ProtocolHeaders_t * pxProtocolHeaders = ( ( ProtocolHeaders_t * )
&( pxNetworkBuffer->pucEthernetBuffer[ ipSIZE_OF_ETH_HEADER + uxIPHeaderSizeSocket( pxSocket ) ] ) );
TCPHeader_t * pxTCPHeader = &pxProtocolHeaders->xTCPHeader;
TCPWindow_t * pxTCPWindow = &pxSocket->u.xTCP.xTCPWindow;
uint8_t ucTCPFlags = pxTCPHeader->ucTCPFlags;
uint32_t ulSequenceNumber = FreeRTOS_ntohl( pxTCPHeader->ulSequenceNumber );
BaseType_t xSendLength = 0;
UBaseType_t uxIntermediateResult = 0U;
/* Either expect a ACK or a SYN+ACK. */
uint8_t ucExpect = tcpTCP_FLAG_ACK;
const uint8_t ucFlagsMask = tcpTCP_FLAG_ACK | tcpTCP_FLAG_RST | tcpTCP_FLAG_SYN | tcpTCP_FLAG_FIN;
if( pxSocket->u.xTCP.eTCPState == eCONNECT_SYN )
{
ucExpect |= tcpTCP_FLAG_SYN;
}
if( ( ucTCPFlags & ucFlagsMask ) != ucExpect )
{
/* eSYN_RECEIVED: flags 0010 expected, not 0002. */
/* eSYN_RECEIVED: flags ACK expected, not SYN. */
FreeRTOS_debug_printf( ( "%s: flags %04X expected, not %04X\n",
( pxSocket->u.xTCP.eTCPState == ( uint8_t ) eSYN_RECEIVED ) ? "eSYN_RECEIVED" : "eCONNECT_SYN",
ucExpect, ucTCPFlags ) );
/* In case pxSocket is not yet owned by the application, a closure
* of the socket will be scheduled for the next cycle. */
vTCPStateChange( pxSocket, eCLOSE_WAIT );
/* Send RST with the expected sequence and ACK numbers,
* otherwise the packet will be ignored. */
pxTCPWindow->ulOurSequenceNumber = FreeRTOS_htonl( pxTCPHeader->ulAckNr );
pxTCPWindow->rx.ulCurrentSequenceNumber = ulSequenceNumber;
pxTCPHeader->ucTCPFlags |= tcpTCP_FLAG_RST;
uxIntermediateResult = uxIPHeaderSizeSocket( pxSocket ) + ipSIZE_OF_TCP_HEADER + uxOptionsLength;
xSendLength = ( BaseType_t ) uxIntermediateResult;
pxTCPHeader->ucTCPOffset = ( uint8_t ) ( ( ipSIZE_OF_TCP_HEADER + uxOptionsLength ) << 2 );
}
else
{
pxTCPWindow->usPeerPortNumber = pxSocket->u.xTCP.usRemotePort;
pxTCPWindow->usOurPortNumber = pxSocket->usLocalPort;
if( pxSocket->u.xTCP.eTCPState == eCONNECT_SYN )
{
/* Map the Last packet onto the ProtocolHeader_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] */
ProtocolHeaders_t * pxLastHeaders = ( ( ProtocolHeaders_t * )
&( pxSocket->u.xTCP.xPacket.u.ucLastPacket[ ipSIZE_OF_ETH_HEADER + uxIPHeaderSizeSocket( pxSocket ) ] ) );
/* Clear the SYN flag in lastPacket. */
pxLastHeaders->xTCPHeader.ucTCPFlags = tcpTCP_FLAG_ACK;
pxProtocolHeaders->xTCPHeader.ucTCPFlags = tcpTCP_FLAG_ACK;
/* This socket was the one connecting actively so now perform the
* synchronisation. */
vTCPWindowInit( &pxSocket->u.xTCP.xTCPWindow,
ulSequenceNumber, pxSocket->u.xTCP.xTCPWindow.ulOurSequenceNumber, ( uint32_t ) pxSocket->u.xTCP.usMSS );
pxTCPWindow->rx.ulHighestSequenceNumber = ulSequenceNumber + 1U;
pxTCPWindow->rx.ulCurrentSequenceNumber = ulSequenceNumber + 1U;
pxTCPWindow->tx.ulCurrentSequenceNumber++; /* because we send a TCP_SYN [ | TCP_ACK ]; */
pxTCPWindow->ulNextTxSequenceNumber++;
}
else if( ulReceiveLength == 0U )
{
pxTCPWindow->rx.ulCurrentSequenceNumber = ulSequenceNumber;
}
else
{
/* Nothing. */
}
/* The SYN+ACK has been confirmed, increase the next sequence number by
* 1. */
pxTCPWindow->ulOurSequenceNumber = pxTCPWindow->tx.ulFirstSequenceNumber + 1U;
#if ( ipconfigUSE_TCP_WIN == 1 )
{
char pcBuffer[ 40 ]; /* Space to print an IP-address. */
( void ) FreeRTOS_inet_ntop( ( pxSocket->bits.bIsIPv6 != 0U ) ? FREERTOS_AF_INET6 : FREERTOS_AF_INET,
( void * ) pxSocket->u.xTCP.xRemoteIP.xIP_IPv6.ucBytes,
pcBuffer,
sizeof( pcBuffer ) );
FreeRTOS_debug_printf( ( "TCP: %s %u => %s port %u set ESTAB (scaling %u)\n",
( pxSocket->u.xTCP.eTCPState == ( uint8_t ) eCONNECT_SYN ) ? "active" : "passive",
pxSocket->usLocalPort,
pcBuffer,
pxSocket->u.xTCP.usRemotePort,
( unsigned ) pxSocket->u.xTCP.bits.bWinScaling ) );
}
#endif /* ipconfigUSE_TCP_WIN */
if( ( pxSocket->u.xTCP.eTCPState == eCONNECT_SYN ) || ( ulReceiveLength != 0U ) )
{
pxTCPHeader->ucTCPFlags = tcpTCP_FLAG_ACK;
uxIntermediateResult = uxIPHeaderSizeSocket( pxSocket ) + ( size_t ) ipSIZE_OF_TCP_HEADER + uxOptionsLength;
xSendLength = ( BaseType_t ) uxIntermediateResult;
pxTCPHeader->ucTCPOffset = ( uint8_t ) ( ( ipSIZE_OF_TCP_HEADER + uxOptionsLength ) << 2 );
}
#if ( ipconfigUSE_TCP_WIN != 0 )
{
if( pxSocket->u.xTCP.bits.bWinScaling == pdFALSE_UNSIGNED )
{
/* The other party did not send a scaling factor.
* A shifting factor in this side must be canceled. */
pxSocket->u.xTCP.ucMyWinScaleFactor = 0;
pxSocket->u.xTCP.ucPeerWinScaleFactor = 0;
}
}
#endif /* ipconfigUSE_TCP_WIN */
/* This was the third step of connecting: SYN, SYN+ACK, ACK so now the
* connection is established. */
vTCPStateChange( pxSocket, eESTABLISHED );
}
return xSendLength;
}
/*-----------------------------------------------------------*/
/**
* @brief prvHandleEstablished(): called from prvTCPHandleState()
* Called if the status is eESTABLISHED. Data reception has been handled
* earlier. Here the ACK's from peer will be checked, and if a FIN is received,
* the code will check if it may be accepted, i.e. if all expected data has been
* completely received.
*
* @param[in] pxSocket The socket owning the connection.
* @param[in,out] ppxNetworkBuffer Pointer to pointer to the network buffer.
* @param[in] ulReceiveLength The length of the received packet.
* @param[in] uxOptionsLength Length of TCP options.
*
* @return The send length of the packet to be sent.
*/
static BaseType_t prvHandleEstablished( FreeRTOS_Socket_t * pxSocket,
NetworkBufferDescriptor_t ** ppxNetworkBuffer,
uint32_t ulReceiveLength,
UBaseType_t uxOptionsLength )
{
/* Map the buffer onto the ProtocolHeader_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] */
ProtocolHeaders_t * pxProtocolHeaders = ( ( ProtocolHeaders_t * )
&( ( *ppxNetworkBuffer )->pucEthernetBuffer[ ipSIZE_OF_ETH_HEADER + uxIPHeaderSizeSocket( pxSocket ) ] ) );
TCPHeader_t * pxTCPHeader = &pxProtocolHeaders->xTCPHeader;
TCPWindow_t * pxTCPWindow = &pxSocket->u.xTCP.xTCPWindow;
uint8_t ucTCPFlags = pxTCPHeader->ucTCPFlags;
uint32_t ulSequenceNumber = FreeRTOS_ntohl( pxTCPHeader->ulSequenceNumber ), ulCount, ulIntermediateResult = 0;
BaseType_t xSendLength = 0, xMayClose = pdFALSE, bRxComplete, bTxDone;
int32_t lDistance, lSendResult;
uint16_t usWindow;
UBaseType_t uxIntermediateResult = 0;
/* Remember the window size the peer is advertising. */
usWindow = FreeRTOS_ntohs( pxTCPHeader->usWindow );
pxSocket->u.xTCP.ulWindowSize = ( uint32_t ) usWindow;
#if ( ipconfigUSE_TCP_WIN != 0 )
{
pxSocket->u.xTCP.ulWindowSize =
( pxSocket->u.xTCP.ulWindowSize << pxSocket->u.xTCP.ucPeerWinScaleFactor );
}
#endif /* ipconfigUSE_TCP_WIN */
if( ( ucTCPFlags & ( uint8_t ) tcpTCP_FLAG_ACK ) == 0U )
{
/* RFC793: If ACK bit is not set at this state, the segment should
* be dropped
*/
}
else
{
ulCount = ulTCPWindowTxAck( pxTCPWindow, FreeRTOS_ntohl( pxTCPHeader->ulAckNr ) );
/* ulTCPWindowTxAck() returns the number of bytes which have been acked,
* starting at 'tx.ulCurrentSequenceNumber'. Advance the tail pointer in
* txStream. */
if( ( pxSocket->u.xTCP.txStream != NULL ) && ( ulCount > 0U ) )
{
/* Just advancing the tail index, 'ulCount' bytes have been
* confirmed, and because there is new space in the txStream, the
* user/owner should be woken up. */
/* _HT_ : only in case the socket's waiting? */
if( uxStreamBufferGet( pxSocket->u.xTCP.txStream, 0U, NULL, ( size_t ) ulCount, pdFALSE ) != 0U )
{
pxSocket->xEventBits |= ( EventBits_t ) eSOCKET_SEND;
#if ipconfigSUPPORT_SELECT_FUNCTION == 1
{
if( ( pxSocket->xSelectBits & ( ( EventBits_t ) eSELECT_WRITE ) ) != 0U )
{
pxSocket->xEventBits |= ( ( EventBits_t ) eSELECT_WRITE ) << SOCKET_EVENT_BIT_COUNT;
}
}
#endif
/* In case the socket owner has installed an OnSent handler,
* call it now. */
#if ( ipconfigUSE_CALLBACKS == 1 )
{
if( ipconfigIS_VALID_PROG_ADDRESS( pxSocket->u.xTCP.pxHandleSent ) )
{
pxSocket->u.xTCP.pxHandleSent( ( Socket_t ) pxSocket, ulCount );
}
}
#endif /* ipconfigUSE_CALLBACKS == 1 */
}
}
/* If this socket has a stream for transmission, add the data to the
* outgoing segment(s). */
if( pxSocket->u.xTCP.txStream != NULL )
{
prvTCPAddTxData( pxSocket );
}
pxSocket->u.xTCP.xTCPWindow.ulOurSequenceNumber = pxTCPWindow->tx.ulCurrentSequenceNumber;
if( ( pxSocket->u.xTCP.bits.bFinAccepted != pdFALSE_UNSIGNED ) || ( ( ucTCPFlags & ( uint8_t ) tcpTCP_FLAG_FIN ) != 0U ) )
{
/* Peer is requesting to stop, see if we're really finished. */
xMayClose = pdTRUE;
/* Checks are only necessary if we haven't sent a FIN yet. */
if( pxSocket->u.xTCP.bits.bFinSent == pdFALSE_UNSIGNED )
{
/* xTCPWindowTxDone returns true when all Tx queues are empty. */
bRxComplete = xTCPWindowRxEmpty( pxTCPWindow );
bTxDone = xTCPWindowTxDone( pxTCPWindow );
if( ( bRxComplete == 0 ) || ( bTxDone == 0 ) )
{
/* Refusing FIN: Rx incomplete 1 optlen 4 tx done 1. */
FreeRTOS_debug_printf( ( "Refusing FIN[%u,%u]: RxCompl %d tx done %d\n",
pxSocket->usLocalPort,
pxSocket->u.xTCP.usRemotePort,
( int ) bRxComplete,
( int ) bTxDone ) );
xMayClose = pdFALSE;
}
else
{
ulIntermediateResult = ulSequenceNumber + ulReceiveLength - pxTCPWindow->rx.ulCurrentSequenceNumber;
lDistance = ( int32_t ) ulIntermediateResult;
if( lDistance > 1 )
{
FreeRTOS_debug_printf( ( "Refusing FIN: Rx not complete %d (cur %u high %u)\n",
( int ) lDistance,
( unsigned ) ( pxTCPWindow->rx.ulCurrentSequenceNumber - pxTCPWindow->rx.ulFirstSequenceNumber ),
( unsigned ) ( pxTCPWindow->rx.ulHighestSequenceNumber - pxTCPWindow->rx.ulFirstSequenceNumber ) ) );
xMayClose = pdFALSE;
}
}
}
if( xTCPWindowLoggingLevel > 0 )
{
FreeRTOS_debug_printf( ( "TCP: FIN received, mayClose = %d (Rx %u Len %d, Tx %u)\n",
( int ) xMayClose,
( unsigned ) ( ulSequenceNumber - pxSocket->u.xTCP.xTCPWindow.rx.ulFirstSequenceNumber ),
( unsigned ) ulReceiveLength,
( unsigned ) ( pxTCPWindow->tx.ulCurrentSequenceNumber - pxSocket->u.xTCP.xTCPWindow.tx.ulFirstSequenceNumber ) ) );
}
if( xMayClose != pdFALSE )
{
pxSocket->u.xTCP.bits.bFinAccepted = pdTRUE_UNSIGNED;
xSendLength = prvTCPHandleFin( pxSocket, *ppxNetworkBuffer );
}
}
if( xMayClose == pdFALSE )
{
pxTCPHeader->ucTCPFlags = tcpTCP_FLAG_ACK;
if( ulReceiveLength != 0U )
{
uxIntermediateResult = uxIPHeaderSizeSocket( pxSocket ) + ipSIZE_OF_TCP_HEADER + uxOptionsLength;
xSendLength = ( BaseType_t ) uxIntermediateResult;
/* TCP-offset equals '( ( length / 4 ) << 4 )', resulting in a shift-left 2 */
pxTCPHeader->ucTCPOffset = ( uint8_t ) ( ( ipSIZE_OF_TCP_HEADER + uxOptionsLength ) << 2 );
if( pxSocket->u.xTCP.bits.bFinSent != pdFALSE_UNSIGNED )
{
pxTCPWindow->tx.ulCurrentSequenceNumber = pxTCPWindow->tx.ulFINSequenceNumber;
}
}
/* Now get data to be transmitted. */
/* _HT_ patch: since the MTU has be fixed at 1500 in stead of 1526, TCP
* can not send-out both TCP options and also a full packet. Sending
* options (SACK) is always more urgent than sending data, which can be
* sent later. */
if( uxOptionsLength == 0U )
{
/* prvTCPPrepareSend might allocate a bigger network buffer, if
* necessary. */
lSendResult = prvTCPPrepareSend( pxSocket, ppxNetworkBuffer, uxOptionsLength );
if( lSendResult > 0 )
{
xSendLength = ( BaseType_t ) lSendResult;
}
}
}
}
return xSendLength;
}
/*-----------------------------------------------------------*/
/**
* @brief Check incoming packets for valid data and handle the state of the
* TCP connection and respond according to the situation.
*
* @param[in] pxSocket The socket whose connection state is being handled.
* @param[in] ppxNetworkBuffer The network buffer descriptor holding the
* packet received from the peer.
*
* @return If the data is correct and some packet was sent to the peer, then
* the number of bytes sent is returned, or else a negative value is
* returned indicating an error.
*
* @note prvTCPHandleState() is the most important function of this TCP stack
* We've tried to keep it (relatively short) by putting a lot of code in
* the static functions above:
*
* prvCheckRxData()
* prvStoreRxData()
* prvSetOptions()
* prvHandleSynReceived()
* prvHandleEstablished()
* prvSendData()
*
* As these functions are declared static, and they're called from one location
* only, most compilers will inline them, thus avoiding a call and return.
*/
BaseType_t prvTCPHandleState( FreeRTOS_Socket_t * pxSocket,
NetworkBufferDescriptor_t ** ppxNetworkBuffer )
{
/* Map the buffer onto the ProtocolHeader_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] */
ProtocolHeaders_t * pxProtocolHeaders = ( ( ProtocolHeaders_t * )
&( ( *ppxNetworkBuffer )->pucEthernetBuffer[ ipSIZE_OF_ETH_HEADER + uxIPHeaderSizePacket( *ppxNetworkBuffer ) ] ) );
TCPHeader_t * pxTCPHeader = &( pxProtocolHeaders->xTCPHeader );
BaseType_t xSendLength = 0;
uint32_t ulReceiveLength; /* Number of bytes contained in the TCP message. */
uint8_t * pucRecvData;
uint32_t ulSequenceNumber = FreeRTOS_ntohl( pxTCPHeader->ulSequenceNumber );
/* uxOptionsLength: the size of the options to be sent (always a multiple of
* 4 bytes)
* 1. in the SYN phase, we shall communicate the MSS
* 2. in case of a SACK, Selective ACK, ack a segment which comes in
* out-of-order. */
UBaseType_t uxOptionsLength = 0U;
uint8_t ucTCPFlags = pxTCPHeader->ucTCPFlags;
TCPWindow_t * pxTCPWindow = &( pxSocket->u.xTCP.xTCPWindow );
UBaseType_t uxIntermediateResult = 0;
uint32_t ulSum;
/* First get the length and the position of the received data, if any.
* pucRecvData will point to the first byte of the TCP payload. */
ulReceiveLength = ( uint32_t ) prvCheckRxData( *ppxNetworkBuffer, &pucRecvData );
if( pxSocket->u.xTCP.eTCPState >= eESTABLISHED )
{
if( pxTCPWindow->rx.ulCurrentSequenceNumber == ( ulSequenceNumber + 1U ) )
{
/* This is most probably a keep-alive message from peer. Setting
* 'bWinChange' doesn't cause a window-size-change, the flag is used
* here to force sending an immediate ACK. */
pxSocket->u.xTCP.bits.bWinChange = pdTRUE_UNSIGNED;
}
}
/* Keep track of the highest sequence number that might be expected within
* this connection. */
ulSum = ulSequenceNumber + ulReceiveLength - pxTCPWindow->rx.ulHighestSequenceNumber;
if( ( ( int32_t ) ulSum ) > 0 )
{
pxTCPWindow->rx.ulHighestSequenceNumber = ulSequenceNumber + ulReceiveLength;
}
/* Storing data may result in a fatal error if malloc() fails. */
if( prvStoreRxData( pxSocket, pucRecvData, *ppxNetworkBuffer, ulReceiveLength ) < 0 )
{
xSendLength = -1;
}
else
{
eIPTCPState_t eState;
uxOptionsLength = prvSetOptions( pxSocket, *ppxNetworkBuffer );
if( ( pxSocket->u.xTCP.eTCPState == eSYN_RECEIVED ) && ( ( ucTCPFlags & ( uint8_t ) tcpTCP_FLAG_CTRL ) == ( uint8_t ) tcpTCP_FLAG_SYN ) )
{
FreeRTOS_debug_printf( ( "eSYN_RECEIVED: ACK expected, not SYN: peer missed our SYN+ACK\n" ) );
/* In eSYN_RECEIVED a simple ACK is expected, but apparently the
* 'SYN+ACK' didn't arrive. Step back to the previous state in which
* a first incoming SYN is handled. The SYN was counted already so
* decrease it first. */
vTCPStateChange( pxSocket, eSYN_FIRST );
}
if( ( ( ucTCPFlags & tcpTCP_FLAG_FIN ) != 0U ) && ( pxSocket->u.xTCP.bits.bFinRecv == pdFALSE_UNSIGNED ) )
{
/* It's the first time a FIN has been received, remember its
* sequence number. */
pxTCPWindow->rx.ulFINSequenceNumber = ulSequenceNumber + ulReceiveLength;
pxSocket->u.xTCP.bits.bFinRecv = pdTRUE_UNSIGNED;
/* Was peer the first one to send a FIN? */
if( pxSocket->u.xTCP.bits.bFinSent == pdFALSE_UNSIGNED )
{
/* If so, don't send the-last-ACK. */
pxSocket->u.xTCP.bits.bFinLast = pdTRUE_UNSIGNED;
}
}
eState = ( eIPTCPState_t ) pxSocket->u.xTCP.eTCPState;
switch( eState )
{
case eCLOSED: /* (server + client) no connection state at all. */
/* Nothing to do for a closed socket, except waiting for the
* owner. */
break;
case eTCP_LISTEN: /* (server) waiting for a connection request from
* any remote TCP and port. */
/* The listen state was handled in xProcessReceivedTCPPacket().
* Should not come here. */
break;
case eSYN_FIRST: /* (server) Just received a SYN request for a server
* socket. */
/* A new socket has been created, reply with a SYN+ACK.
* Acknowledge with seq+1 because the SYN is seen as pseudo data
* with len = 1. */
uxOptionsLength = prvSetSynAckOptions( pxSocket, pxTCPHeader );
pxTCPHeader->ucTCPFlags = ( uint8_t ) tcpTCP_FLAG_SYN | ( uint8_t ) tcpTCP_FLAG_ACK;
uxIntermediateResult = uxIPHeaderSizeSocket( pxSocket ) + ipSIZE_OF_TCP_HEADER + uxOptionsLength;
xSendLength = ( BaseType_t ) uxIntermediateResult;
/* Set the TCP offset field: ipSIZE_OF_TCP_HEADER equals 20 and
* uxOptionsLength is a multiple of 4. The complete expression is:
* ucTCPOffset = ( ( ipSIZE_OF_TCP_HEADER + uxOptionsLength ) / 4 ) << 4 */
pxTCPHeader->ucTCPOffset = ( uint8_t ) ( ( ipSIZE_OF_TCP_HEADER + uxOptionsLength ) << 2 );
vTCPStateChange( pxSocket, eSYN_RECEIVED );
pxTCPWindow->rx.ulHighestSequenceNumber = ulSequenceNumber + 1U;
pxTCPWindow->rx.ulCurrentSequenceNumber = ulSequenceNumber + 1U;
pxTCPWindow->ulNextTxSequenceNumber = pxTCPWindow->tx.ulFirstSequenceNumber + 1U;
pxTCPWindow->tx.ulCurrentSequenceNumber = pxTCPWindow->tx.ulFirstSequenceNumber + 1U; /* because we send a TCP_SYN. */
break;
case eCONNECT_SYN: /* (client) also called SYN_SENT: we've just send a
* SYN, expect a SYN+ACK and send a ACK now. */
/* Fall through */
case eSYN_RECEIVED: /* (server) we've had a SYN, replied with SYN+SCK
* expect a ACK and do nothing. */
xSendLength = prvHandleSynReceived( pxSocket, *( ppxNetworkBuffer ), ulReceiveLength, uxOptionsLength );
break;
case eESTABLISHED: /* (server + client) an open connection, data
* received can be delivered to the user. The normal
* state for the data transfer phase of the connection
* The closing states are also handled here with the
* use of some flags. */
xSendLength = prvHandleEstablished( pxSocket, ppxNetworkBuffer, ulReceiveLength, uxOptionsLength );
break;
case eLAST_ACK: /* (server + client) waiting for an acknowledgement
* of the connection termination request previously
* sent to the remote TCP (which includes an
* acknowledgement of its connection termination
* request). */
/* Fall through */
case eFIN_WAIT_1: /* (server + client) waiting for a connection termination request from the remote TCP,
* or an acknowledgement of the connection termination request previously sent. */
/* Fall through */
case eFIN_WAIT_2: /* (server + client) waiting for a connection termination request from the remote TCP. */
xSendLength = prvTCPHandleFin( pxSocket, *ppxNetworkBuffer );
break;
case eCLOSE_WAIT: /* (server + client) waiting for a connection
* termination request from the local user. Nothing to
* do, connection is closed, wait for owner to close
* this socket. */
break;
case eCLOSING: /* (server + client) waiting for a connection
* termination request acknowledgement from the remote
* TCP. */
break;
case eTIME_WAIT: /* (either server or client) waiting for enough time
* to pass to be sure the remote TCP received the
* acknowledgement of its connection termination
* request. [According to RFC 793 a connection can stay
* in TIME-WAIT for a maximum of four minutes known as
* a MSL (maximum segment lifetime).] These states are
* implemented implicitly by settings flags like
* 'bFinSent', 'bFinRecv', and 'bFinAcked'. */
break;
default:
/* No more known states. */
break;
}
}
if( xSendLength > 0 )
{
xSendLength = prvSendData( pxSocket, ppxNetworkBuffer, ulReceiveLength, xSendLength );
}
return xSendLength;
}
/*-----------------------------------------------------------*/
/**
* @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( FreeRTOS_Socket_t * pxSocket,
NetworkBufferDescriptor_t * pxNetworkBuffer )
{
FreeRTOS_Socket_t * pxNewSocket = NULL;
switch( uxIPHeaderSizePacket( pxNetworkBuffer ) )
{
#if ( ipconfigUSE_IPv4 != 0 )
case ipSIZE_OF_IPv4_HEADER:
pxNewSocket = prvHandleListen_IPV4( pxSocket, pxNetworkBuffer );
break;
#endif /* ( ipconfigUSE_IPv4 != 0 ) */
#if ( ipconfigUSE_IPv6 != 0 )
case ipSIZE_OF_IPv6_HEADER:
pxNewSocket = prvHandleListen_IPV6( pxSocket, pxNetworkBuffer );
break;
#endif /* ( ipconfigUSE_IPv6 != 0 ) */
default:
/* Shouldn't reach here */
/* MISRA 16.4 Compliance */
break;
}
return pxNewSocket;
}
/*-----------------------------------------------------------*/
/**
* @brief Duplicates a socket after a listening socket receives a connection and bind
* the new socket to the same port as the listening socket.
* Also, let the new socket inherit all properties from the listening socket.
*
* @param[in] pxNewSocket Pointer to the new socket.
* @param[in] pxSocket Pointer to the socket being duplicated.
*
* @return If all steps all successful, then pdTRUE is returned. Else, pdFALSE.
*/
BaseType_t prvTCPSocketCopy( FreeRTOS_Socket_t * pxNewSocket,
FreeRTOS_Socket_t * pxSocket )
{
struct freertos_sockaddr xAddress;
BaseType_t xResult;
pxNewSocket->xReceiveBlockTime = pxSocket->xReceiveBlockTime;
pxNewSocket->xSendBlockTime = pxSocket->xSendBlockTime;
pxNewSocket->ucSocketOptions = pxSocket->ucSocketOptions;
pxNewSocket->u.xTCP.uxRxStreamSize = pxSocket->u.xTCP.uxRxStreamSize;
pxNewSocket->u.xTCP.uxTxStreamSize = pxSocket->u.xTCP.uxTxStreamSize;
pxNewSocket->u.xTCP.uxLittleSpace = pxSocket->u.xTCP.uxLittleSpace;
pxNewSocket->u.xTCP.uxEnoughSpace = pxSocket->u.xTCP.uxEnoughSpace;
pxNewSocket->u.xTCP.uxRxWinSize = pxSocket->u.xTCP.uxRxWinSize;
pxNewSocket->u.xTCP.uxTxWinSize = pxSocket->u.xTCP.uxTxWinSize;
#if ( ipconfigSOCKET_HAS_USER_SEMAPHORE == 1 )
{
pxNewSocket->pxUserSemaphore = pxSocket->pxUserSemaphore;
}
#endif /* ipconfigSOCKET_HAS_USER_SEMAPHORE */
#if ( ipconfigUSE_CALLBACKS == 1 )
{
/* In case call-backs are used, copy them from parent to child. */
pxNewSocket->u.xTCP.pxHandleConnected = pxSocket->u.xTCP.pxHandleConnected;
pxNewSocket->u.xTCP.pxHandleReceive = pxSocket->u.xTCP.pxHandleReceive;
pxNewSocket->u.xTCP.pxHandleSent = pxSocket->u.xTCP.pxHandleSent;
}
#endif /* ipconfigUSE_CALLBACKS */
#if ( ipconfigSUPPORT_SELECT_FUNCTION == 1 )
{
/* Child socket of listening sockets will inherit the Socket Set
* Otherwise the owner has no chance of including it into the set. */
if( pxSocket->pxSocketSet != NULL )
{
pxNewSocket->pxSocketSet = pxSocket->pxSocketSet;
pxNewSocket->xSelectBits = pxSocket->xSelectBits | ( ( EventBits_t ) eSELECT_READ ) | ( ( EventBits_t ) eSELECT_EXCEPT );
}
}
#endif /* ipconfigSUPPORT_SELECT_FUNCTION */
/* And bind it to the same local port as its parent. */
/*TODO xAddress.sin_address.ulIP_IPv4 = *ipLOCAL_IP_ADDRESS_POINTER; */
xAddress.sin_port = FreeRTOS_htons( pxSocket->usLocalPort );
#if ( ipconfigTCP_HANG_PROTECTION == 1 )
{
/* Only when there is anti-hanging protection, a socket may become an
* orphan temporarily. Once this socket is really connected, the owner of
* the server socket will be notified. */
/* When bPassQueued is true, the socket is an orphan until it gets
* connected. */
pxNewSocket->u.xTCP.bits.bPassQueued = pdTRUE_UNSIGNED;
pxNewSocket->u.xTCP.pxPeerSocket = pxSocket;
}
#else
{
/* A reference to the new socket may be stored and the socket is marked
* as 'passable'. */
/* When bPassAccept is true, this socket may be returned in a call to
* accept(). */
pxNewSocket->u.xTCP.bits.bPassAccept = pdTRUE_UNSIGNED;
if( pxSocket->u.xTCP.pxPeerSocket == NULL )
{
pxSocket->u.xTCP.pxPeerSocket = pxNewSocket;
}
}
#endif /* if ( ipconfigTCP_HANG_PROTECTION == 1 ) */
pxSocket->u.xTCP.usChildCount++;
FreeRTOS_debug_printf( ( "Gain: Socket %u now has %u / %u child%s\n",
pxSocket->usLocalPort,
pxSocket->u.xTCP.usChildCount,
pxSocket->u.xTCP.usBacklog,
( pxSocket->u.xTCP.usChildCount == 1U ) ? "" : "ren" ) );
/* Now bind the child socket to the same port as the listening socket. */
if( vSocketBind( pxNewSocket, &xAddress, sizeof( xAddress ), pdTRUE ) != 0 )
{
FreeRTOS_debug_printf( ( "TCP: Listen: new socket bind error\n" ) );
( void ) vSocketClose( pxNewSocket );
xResult = pdFALSE;
}
else
{
xResult = pdTRUE;
}
return xResult;
}
/*-----------------------------------------------------------*/
#if ( ( ipconfigHAS_DEBUG_PRINTF != 0 ) || ( ipconfigHAS_PRINTF != 0 ) )
const char * FreeRTOS_GetTCPStateName( UBaseType_t ulState )
{
static const char * const pcStateNames[] =
{
"eCLOSED",
"eTCP_LISTEN",
"eCONNECT_SYN",
"eSYN_FIRST",
"eSYN_RECEIVED",
"eESTABLISHED",
"eFIN_WAIT_1",
"eFIN_WAIT_2",
"eCLOSE_WAIT",
"eCLOSING",
"eLAST_ACK",
"eTIME_WAIT",
"eUNKNOWN",
};
BaseType_t xIndex = ( BaseType_t ) ulState;
if( ( xIndex < 0 ) || ( xIndex >= ARRAY_SIZE( pcStateNames ) ) )
{
/* The last item is called 'eUNKNOWN' */
xIndex = ARRAY_SIZE( pcStateNames );
xIndex--;
}
return pcStateNames[ xIndex ];
}
#endif /* ( ( ipconfigHAS_DEBUG_PRINTF != 0 ) || ( ipconfigHAS_PRINTF != 0 ) ) */
/*-----------------------------------------------------------*/
#endif /* ipconfigUSE_TCP == 1 */