/* * FreeRTOS+TCP V3.1.0 * 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_WIN.c * @brief Module which handles the TCP windowing schemes for FreeRTOS+TCP. Many * functions have two versions - one for FreeRTOS+TCP (full) and one for * FreeRTOS+TCP (lite). * * In this module all ports and IP addresses and sequence numbers are * being stored in host byte-order. */ /* Standard includes. */ #include /* FreeRTOS includes. */ #include "FreeRTOS.h" #include "task.h" /* FreeRTOS+TCP includes. */ #include "FreeRTOS_IP.h" #include "FreeRTOS_UDP_IP.h" #include "FreeRTOS_Sockets.h" #include "FreeRTOS_IP_Private.h" #if ( ipconfigUSE_TCP == 1 ) /* Constants used for Smoothed Round Trip Time (SRTT). */ #define winSRTT_INCREMENT_NEW 2 /**< New increment for the smoothed RTT. */ #define winSRTT_INCREMENT_CURRENT 6 /**< Current increment for the smoothed RTT. */ #define winSRTT_DECREMENT_NEW 1 /**< New decrement for the smoothed RTT. */ #define winSRTT_DECREMENT_CURRENT 7 /**< Current decrement for the smoothed RTT. */ #define winSRTT_CAP_mS ( ipconfigTCP_SRTT_MINIMUM_VALUE_MS ) /**< Cap in milliseconds. */ #if ( ipconfigUSE_TCP_WIN == 1 ) /** @brief Create a new Rx window. */ #define xTCPWindowRxNew( pxWindow, ulSequenceNumber, lCount ) xTCPWindowNew( pxWindow, ulSequenceNumber, lCount, pdTRUE ) /** @brief Create a new Tx window. */ #define xTCPWindowTxNew( pxWindow, ulSequenceNumber, lCount ) xTCPWindowNew( pxWindow, ulSequenceNumber, lCount, pdFALSE ) /** @brief The code to send a single Selective ACK (SACK): * NOP (0x01), NOP (0x01), SACK (0x05), LEN (0x0a), * followed by a lower and a higher sequence number, * where LEN is 2 + 2*4 = 10 bytes. */ #if ( ipconfigBYTE_ORDER == pdFREERTOS_BIG_ENDIAN ) #define OPTION_CODE_SINGLE_SACK ( 0x0101050aU ) #else #define OPTION_CODE_SINGLE_SACK ( 0x0a050101U ) #endif /** @brief Normal retransmission: * A packet will be retransmitted after a Retransmit Time-Out (RTO). * Fast retransmission: * When 3 packets with a higher sequence number have been acknowledged * by the peer, it is very unlikely a current packet will ever arrive. * It will be retransmitted far before the RTO. */ #define DUPLICATE_ACKS_BEFORE_FAST_RETRANSMIT ( 3U ) /** @brief If there have been several retransmissions (4), decrease the * size of the transmission window to at most 2 times MSS. */ #define MAX_TRANSMIT_COUNT_USING_LARGE_WINDOW ( 4U ) #endif /* configUSE_TCP_WIN */ /*-----------------------------------------------------------*/ static void vListInsertGeneric( List_t * const pxList, ListItem_t * const pxNewListItem, MiniListItem_t * pxWhere ); /* * All TCP sockets share a pool of segment descriptors (TCPSegment_t) * Available descriptors are stored in the 'xSegmentList' * When a socket owns a descriptor, it will either be stored in * 'xTxSegments' or 'xRxSegments' * As soon as a package has been confirmed, the descriptor will be returned * to the segment pool */ #if ( ipconfigUSE_TCP_WIN == 1 ) static BaseType_t prvCreateSectors( void ); #endif /* ipconfigUSE_TCP_WIN == 1 */ /* * Find a segment with a given sequence number in the list of received * segments: 'pxWindow->xRxSegments'. */ #if ( ipconfigUSE_TCP_WIN == 1 ) static TCPSegment_t * xTCPWindowRxFind( const TCPWindow_t * pxWindow, uint32_t ulSequenceNumber ); #endif /* ipconfigUSE_TCP_WIN == 1 */ /* * Allocate a new segment * The socket will borrow all segments from a common pool: 'xSegmentList', * which is a list of 'TCPSegment_t' */ #if ( ipconfigUSE_TCP_WIN == 1 ) static TCPSegment_t * xTCPWindowNew( TCPWindow_t * pxWindow, uint32_t ulSequenceNumber, int32_t lCount, BaseType_t xIsForRx ); #endif /* ipconfigUSE_TCP_WIN == 1 */ /* * Detaches and returns the head of a queue */ #if ( ipconfigUSE_TCP_WIN == 1 ) static TCPSegment_t * xTCPWindowGetHead( const List_t * pxList ); #endif /* ipconfigUSE_TCP_WIN == 1 */ /* * Returns the head of a queue but it won't be detached */ #if ( ipconfigUSE_TCP_WIN == 1 ) static TCPSegment_t * xTCPWindowPeekHead( const List_t * pxList ); #endif /* ipconfigUSE_TCP_WIN == 1 */ /* * Free entry pxSegment because it's not used anymore * The ownership will be passed back to the segment pool */ #if ( ipconfigUSE_TCP_WIN == 1 ) static void vTCPWindowFree( TCPSegment_t * pxSegment ); #endif /* ipconfigUSE_TCP_WIN == 1 */ /* * A segment has been received with sequence number 'ulSequenceNumber', where * 'ulCurrentSequenceNumber == ulSequenceNumber', which means that exactly this * segment was expected. xTCPWindowRxConfirm() will check if there is already * another segment with a sequence number between (ulSequenceNumber) and * (ulSequenceNumber+xLength). Normally none will be found, because the next Rx * segment should have a sequence number equal to '(ulSequenceNumber+xLength)'. */ #if ( ipconfigUSE_TCP_WIN == 1 ) static TCPSegment_t * xTCPWindowRxConfirm( const TCPWindow_t * pxWindow, uint32_t ulSequenceNumber, uint32_t ulLength ); #endif /* ipconfigUSE_TCP_WIN == 1 */ /* * FreeRTOS+TCP stores data in circular buffers. Calculate the next position to * store. */ #if ( ipconfigUSE_TCP_WIN == 1 ) static int32_t lTCPIncrementTxPosition( int32_t lPosition, int32_t lMax, int32_t lCount ); #endif /* ipconfigUSE_TCP_WIN == 1 */ /* * This function will look if there is new transmission data. It will return * true if there is data to be sent. */ #if ( ipconfigUSE_TCP_WIN == 1 ) static BaseType_t prvTCPWindowTxHasSpace( TCPWindow_t const * pxWindow, uint32_t ulWindowSize ); #endif /* ipconfigUSE_TCP_WIN == 1 */ /* * An acknowledge was received. See if some outstanding data may be removed * from the transmission queue(s). */ #if ( ipconfigUSE_TCP_WIN == 1 ) static uint32_t prvTCPWindowTxCheckAck( TCPWindow_t * pxWindow, uint32_t ulFirst, uint32_t ulLast ); #endif /* ipconfigUSE_TCP_WIN == 1 */ /* * A higher Tx block has been acknowledged. Now iterate through the xWaitQueue * to find a possible condition for a FAST retransmission. */ #if ( ipconfigUSE_TCP_WIN == 1 ) static uint32_t prvTCPWindowFastRetransmit( TCPWindow_t * pxWindow, uint32_t ulFirst ); #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ /**< TCP segment pool. */ #if ( ipconfigUSE_TCP_WIN == 1 ) static TCPSegment_t * xTCPSegments = NULL; #endif /* ipconfigUSE_TCP_WIN == 1 */ /**< List of free TCP segments. */ #if ( ipconfigUSE_TCP_WIN == 1 ) _static List_t xSegmentList; #endif #if ( ipconfigUSE_TCP_WIN == 1 ) /** @brief Logging verbosity level. */ BaseType_t xTCPWindowLoggingLevel = 0; #endif #if ( ipconfigUSE_TCP_WIN == 1 ) /* Some 32-bit arithmetic: comparing sequence numbers */ static portINLINE BaseType_t xSequenceLessThanOrEqual( uint32_t a, uint32_t b ); /** * @brief Check if a <= b. * * @param[in] a: The value on the left-hand side. * @param[in] b: The value on the right-hand side. * * @return pdTRUE when "( b - a ) < 0x80000000". Else, pdFALSE. */ static portINLINE BaseType_t xSequenceLessThanOrEqual( uint32_t a, uint32_t b ) { BaseType_t xResult = pdFALSE; /* Test if a <= b * Return true if the unsigned subtraction of (b-a) doesn't generate an * arithmetic overflow. */ if( ( ( b - a ) & 0x80000000U ) == 0U ) { xResult = pdTRUE; } return xResult; } #endif /* ipconfigUSE_TCP_WIN */ /*-----------------------------------------------------------*/ /** * @brief Check if a < b. * * @param[in] a: The value on the left-hand side. * @param[in] b: The value on the right-hand side. * * @return pdTRUE when "( b - ( a + 1 ) ) < 0x80000000", else pdFALSE. */ BaseType_t xSequenceLessThan( uint32_t a, uint32_t b ) { BaseType_t xResult = pdFALSE; /* Test if a < b */ if( ( ( b - ( a + 1U ) ) & 0x80000000U ) == 0U ) { xResult = pdTRUE; } return xResult; } /*-----------------------------------------------------------*/ /** * @brief Check if a > b. * * @param[in] a: The value on the left-hand side. * @param[in] b: The value on the right-hand side. * * @return pdTRUE when "( a - b ) < 0x80000000", else pdFALSE. */ BaseType_t xSequenceGreaterThan( uint32_t a, uint32_t b ) { BaseType_t xResult = pdFALSE; /* Test if a > b */ if( ( ( a - ( b + 1U ) ) & 0x80000000U ) == 0U ) { xResult = pdTRUE; } return xResult; } /*-----------------------------------------------------------*/ static portINLINE BaseType_t xSequenceGreaterThanOrEqual( uint32_t a, uint32_t b ); /** * @brief Test if a>=b. This function is required since the sequence numbers can roll over. * * @param[in] a: The first sequence number. * @param[in] b: The second sequence number. * * @return pdTRUE if a>=b, else pdFALSE. */ static portINLINE BaseType_t xSequenceGreaterThanOrEqual( uint32_t a, uint32_t b ) { BaseType_t xResult = pdFALSE; /* Test if a >= b */ if( ( ( a - b ) & 0x80000000U ) == 0U ) { xResult = pdTRUE; } return xResult; } /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) static portINLINE void vListInsertFifo( List_t * const pxList, ListItem_t * const pxNewListItem ); /** * @brief Insert the given item in the list in FIFO manner. * * @param[in] pxList: The list in which the item is to inserted. * @param[in] pxNewListItem: The item to be inserted. */ static portINLINE void vListInsertFifo( List_t * const pxList, ListItem_t * const pxNewListItem ) { vListInsertGeneric( pxList, pxNewListItem, &pxList->xListEnd ); } #endif /*-----------------------------------------------------------*/ static portINLINE void vTCPTimerSet( TCPTimer_t * pxTimer ); /** * @brief Set the timer's "born" time. * * @param[in] pxTimer: The TCP timer. */ static portINLINE void vTCPTimerSet( TCPTimer_t * pxTimer ) { pxTimer->uxBorn = xTaskGetTickCount(); } /*-----------------------------------------------------------*/ static portINLINE uint32_t ulTimerGetAge( const TCPTimer_t * pxTimer ); /** * @brief Get the timer age in milliseconds. * * @param[in] pxTimer: The timer whose age is to be fetched. * * @return The time in milliseconds since the timer was born. */ static portINLINE uint32_t ulTimerGetAge( const TCPTimer_t * pxTimer ) { TickType_t uxNow = xTaskGetTickCount(); TickType_t uxDiff = uxNow - pxTimer->uxBorn; return uxDiff * portTICK_PERIOD_MS; } /*-----------------------------------------------------------*/ /** * @brief Insert a new list item into a list. * * @param[in] pxList: The list in which the item is to be inserted. * @param[in] pxNewListItem: The item to be inserted. * @param[in] pxWhere: Where should the item be inserted. */ static void vListInsertGeneric( List_t * const pxList, ListItem_t * const pxNewListItem, MiniListItem_t * pxWhere ) { /* Insert a new list item into pxList, it does not sort the list, * but it puts the item just before xListEnd, so it will be the last item * returned by listGET_HEAD_ENTRY() */ /* 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] */ pxNewListItem->pxNext = ( ( ListItem_t * ) pxWhere ); pxNewListItem->pxPrevious = pxWhere->pxPrevious; pxWhere->pxPrevious->pxNext = pxNewListItem; pxWhere->pxPrevious = pxNewListItem; /* Remember which list the item is in. */ listLIST_ITEM_CONTAINER( pxNewListItem ) = ( struct xLIST * configLIST_VOLATILE ) pxList; ( pxList->uxNumberOfItems )++; } /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Creates a pool of 'ipconfigTCP_WIN_SEG_COUNT' sector buffers. Should be called once only. * * @return When the allocation was successful: pdPASS, otherwise pdFAIL. */ static BaseType_t prvCreateSectors( void ) { BaseType_t xIndex; BaseType_t xReturn; /* Allocate space for 'xTCPSegments' and store them in 'xSegmentList'. */ vListInitialise( &xSegmentList ); xTCPSegments = ( ( TCPSegment_t * ) pvPortMallocLarge( ( size_t ) ipconfigTCP_WIN_SEG_COUNT * sizeof( xTCPSegments[ 0 ] ) ) ); if( xTCPSegments == NULL ) { FreeRTOS_debug_printf( ( "prvCreateSectors: malloc %u failed\n", ( unsigned ) ( ipconfigTCP_WIN_SEG_COUNT * sizeof( xTCPSegments[ 0 ] ) ) ) ); xReturn = pdFAIL; } else { /* Clear the allocated space. */ ( void ) memset( xTCPSegments, 0, ( size_t ) ipconfigTCP_WIN_SEG_COUNT * sizeof( xTCPSegments[ 0 ] ) ); for( xIndex = 0; xIndex < ipconfigTCP_WIN_SEG_COUNT; xIndex++ ) { /* Could call vListInitialiseItem here but all data has been * nulled already. Set the owner to a segment descriptor. */ #if ( configUSE_LIST_DATA_INTEGRITY_CHECK_BYTES == 1 ) { vListInitialiseItem( &( xTCPSegments[ xIndex ].xSegmentItem ) ); vListInitialiseItem( &( xTCPSegments[ xIndex ].xQueueItem ) ); } #endif listSET_LIST_ITEM_OWNER( &( xTCPSegments[ xIndex ].xSegmentItem ), ( void * ) &( xTCPSegments[ xIndex ] ) ); listSET_LIST_ITEM_OWNER( &( xTCPSegments[ xIndex ].xQueueItem ), ( void * ) &( xTCPSegments[ xIndex ] ) ); /* And add it to the pool of available segments */ vListInsertFifo( &xSegmentList, &( xTCPSegments[ xIndex ].xSegmentItem ) ); } xReturn = pdPASS; } return xReturn; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Find a segment with a given sequence number in the list of received segments. * * @param[in] pxWindow: The descriptor of the TCP sliding windows. * @param[in] ulSequenceNumber: the sequence number to look-up * * @return The address of the segment descriptor found, or NULL when not found. */ static TCPSegment_t * xTCPWindowRxFind( const TCPWindow_t * pxWindow, uint32_t ulSequenceNumber ) { const ListItem_t * pxIterator; const ListItem_t * pxEnd; TCPSegment_t * pxSegment, * pxReturn = NULL; /* Find a segment with a given sequence number in the list of received * segments. */ /* 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] */ pxEnd = ( ( const ListItem_t * ) &( pxWindow->xRxSegments.xListEnd ) ); for( pxIterator = listGET_NEXT( pxEnd ); pxIterator != pxEnd; pxIterator = listGET_NEXT( pxIterator ) ) { pxSegment = ( ( TCPSegment_t * ) listGET_LIST_ITEM_OWNER( pxIterator ) ); if( pxSegment->ulSequenceNumber == ulSequenceNumber ) { pxReturn = pxSegment; break; } } return pxReturn; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Allocate a new segment object, either for transmission or reception. * * @param[in] pxWindow: The descriptor of the TCP sliding windows. * @param[in] ulSequenceNumber: The sequence number. * @param[in] lCount: The number of bytes stored in this segment. * @param[in] xIsForRx: True when this is a reception segment. * * @return Allocate and initialise a segment descriptor, or NULL when none was available. */ static TCPSegment_t * xTCPWindowNew( TCPWindow_t * pxWindow, uint32_t ulSequenceNumber, int32_t lCount, BaseType_t xIsForRx ) { TCPSegment_t * pxSegment; ListItem_t * pxItem; /* Allocate a new segment. The socket will borrow all segments from a * common pool: 'xSegmentList', which is a list of 'TCPSegment_t' */ if( listLIST_IS_EMPTY( &xSegmentList ) != pdFALSE ) { /* If the TCP-stack runs out of segments, you might consider * increasing 'ipconfigTCP_WIN_SEG_COUNT'. */ FreeRTOS_debug_printf( ( "xTCPWindow%cxNew: Error: all segments occupied\n", ( xIsForRx != 0 ) ? 'R' : 'T' ) ); pxSegment = NULL; } else { /* Pop the item at the head of the list. Semaphore protection is * not required as only the IP task will call these functions. */ pxItem = ( ListItem_t * ) listGET_HEAD_ENTRY( &xSegmentList ); pxSegment = ( ( TCPSegment_t * ) listGET_LIST_ITEM_OWNER( pxItem ) ); configASSERT( pxItem != NULL ); configASSERT( pxSegment != NULL ); /* Remove the item from xSegmentList. */ ( void ) uxListRemove( pxItem ); /* Add it to either the connections' Rx or Tx queue. */ if( xIsForRx != 0 ) { vListInsertFifo( &pxWindow->xRxSegments, pxItem ); } else { vListInsertFifo( &pxWindow->xTxSegments, pxItem ); } /* And set the segment's timer to zero */ vTCPTimerSet( &pxSegment->xTransmitTimer ); pxSegment->u.ulFlags = 0; pxSegment->u.bits.bIsForRx = ( xIsForRx != 0 ) ? 1U : 0U; pxSegment->lMaxLength = lCount; pxSegment->lDataLength = lCount; pxSegment->ulSequenceNumber = ulSequenceNumber; #if ( ipconfigHAS_DEBUG_PRINTF != 0 ) { static UBaseType_t xLowestLength = ipconfigTCP_WIN_SEG_COUNT; UBaseType_t xLength = listCURRENT_LIST_LENGTH( &xSegmentList ); if( xLowestLength > xLength ) { xLowestLength = xLength; } } #endif /* ipconfigHAS_DEBUG_PRINTF */ } return pxSegment; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief See if the peer has more packets for this node, before allowing to shut down the connection. * * @param[in] pxWindow: The descriptor of the TCP sliding windows. * * @return pdTRUE if the connection can be closed. Else, pdFALSE. */ BaseType_t xTCPWindowRxEmpty( const TCPWindow_t * pxWindow ) { BaseType_t xReturn; /* When the peer has a close request (FIN flag), the driver will check * if there are missing packets in the Rx-queue. It will accept the * closure of the connection if both conditions are true: * - the Rx-queue is empty * - the highest Rx sequence number has been ACK'ed */ if( listLIST_IS_EMPTY( ( &pxWindow->xRxSegments ) ) == pdFALSE ) { /* Rx data has been stored while earlier packets were missing. */ xReturn = pdFALSE; } else if( xSequenceGreaterThanOrEqual( pxWindow->rx.ulCurrentSequenceNumber + 1U, pxWindow->rx.ulHighestSequenceNumber ) != pdFALSE ) { /* No Rx packets are being stored and the highest sequence number * that has been received has been ACKed. */ xReturn = pdTRUE; } else { FreeRTOS_debug_printf( ( "xTCPWindowRxEmpty: cur %u highest %u (empty)\n", ( unsigned ) ( pxWindow->rx.ulCurrentSequenceNumber - pxWindow->rx.ulFirstSequenceNumber ), ( unsigned ) ( pxWindow->rx.ulHighestSequenceNumber - pxWindow->rx.ulFirstSequenceNumber ) ) ); xReturn = pdFALSE; } return xReturn; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Remove the head item of a list (generic function). * * @param[in] pxList: The list of segment descriptors. * * @return The address of the segment descriptor, or NULL when not found. */ static TCPSegment_t * xTCPWindowGetHead( const List_t * pxList ) { TCPSegment_t * pxSegment; ListItem_t * pxItem; /* Detaches and returns the head of a queue. */ if( listLIST_IS_EMPTY( pxList ) != pdFALSE ) { pxSegment = NULL; } else { pxItem = ( ListItem_t * ) listGET_HEAD_ENTRY( pxList ); pxSegment = ( ( TCPSegment_t * ) listGET_LIST_ITEM_OWNER( pxItem ) ); ( void ) uxListRemove( pxItem ); } return pxSegment; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Return the head item of a list (generic function). * * @param[in] pxList: The list of segment descriptors. * * @return The address of the segment descriptor, or NULL when the list is empty. */ static TCPSegment_t * xTCPWindowPeekHead( const List_t * pxList ) { const ListItem_t * pxItem; TCPSegment_t * pxReturn; /* Returns the head of a queue but it won't be detached. */ if( listLIST_IS_EMPTY( pxList ) != pdFALSE ) { pxReturn = NULL; } else { pxItem = ( ListItem_t * ) listGET_HEAD_ENTRY( pxList ); pxReturn = ( ( TCPSegment_t * ) listGET_LIST_ITEM_OWNER( pxItem ) ); } return pxReturn; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Release a segment object, return it to the list of available segment holders. * * @param[in] pxSegment: The segment descriptor that must be freed. */ static void vTCPWindowFree( TCPSegment_t * pxSegment ) { /* Free entry pxSegment because it's not used any more. The ownership * will be passed back to the segment pool. * * Unlink it from one of the queues, if any. */ if( listLIST_ITEM_CONTAINER( &( pxSegment->xQueueItem ) ) != NULL ) { ( void ) uxListRemove( &( pxSegment->xQueueItem ) ); } pxSegment->ulSequenceNumber = 0U; pxSegment->lDataLength = 0; pxSegment->u.ulFlags = 0U; /* Take it out of xRxSegments/xTxSegments */ if( listLIST_ITEM_CONTAINER( &( pxSegment->xSegmentItem ) ) != NULL ) { ( void ) uxListRemove( &( pxSegment->xSegmentItem ) ); } /* Return it to xSegmentList */ vListInsertFifo( &xSegmentList, &( pxSegment->xSegmentItem ) ); } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Return all segment descriptor to the poll of descriptors, before deleting a socket. * * @param[in] pxWindow: The descriptor of the TCP sliding windows. */ void vTCPWindowDestroy( TCPWindow_t const * pxWindow ) { const List_t * pxSegments; BaseType_t xRound; TCPSegment_t * pxSegment; /* Destroy a window. A TCP window doesn't serve any more. Return all * owned segments to the pool. In order to save code, it will make 2 rounds, * one to remove the segments from xRxSegments, and a second round to clear * xTxSegments*/ for( xRound = 0; xRound < 2; xRound++ ) { if( xRound != 0 ) { pxSegments = &( pxWindow->xRxSegments ); } else { pxSegments = &( pxWindow->xTxSegments ); } if( listLIST_IS_INITIALISED( pxSegments ) ) { while( listCURRENT_LIST_LENGTH( pxSegments ) > 0U ) { pxSegment = ( ( TCPSegment_t * ) listGET_OWNER_OF_HEAD_ENTRY( pxSegments ) ); vTCPWindowFree( pxSegment ); } } } } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ /** * @brief Create a window for TCP. * * @param[in] pxWindow: The window to be created. * @param[in] ulRxWindowLength: The length of the receive window. * @param[in] ulTxWindowLength: The length of the transmit window. * @param[in] ulAckNumber: The first ACK number. * @param[in] ulSequenceNumber: The first sequence number. * @param[in] ulMSS: The MSS of the connection. */ void vTCPWindowCreate( TCPWindow_t * pxWindow, uint32_t ulRxWindowLength, uint32_t ulTxWindowLength, uint32_t ulAckNumber, uint32_t ulSequenceNumber, uint32_t ulMSS ) { /* Create and initialize a window. */ #if ( ipconfigUSE_TCP_WIN == 1 ) { if( xTCPSegments == NULL ) { ( void ) prvCreateSectors(); } vListInitialise( &( pxWindow->xTxSegments ) ); vListInitialise( &( pxWindow->xRxSegments ) ); vListInitialise( &( pxWindow->xPriorityQueue ) ); /* Priority queue: segments which must be sent immediately */ vListInitialise( &( pxWindow->xTxQueue ) ); /* Transmit queue: segments queued for transmission */ vListInitialise( &( pxWindow->xWaitQueue ) ); /* Waiting queue: outstanding segments */ } #endif /* ipconfigUSE_TCP_WIN == 1 */ if( xTCPWindowLoggingLevel != 0 ) { FreeRTOS_debug_printf( ( "vTCPWindowCreate: for WinLen = Rx/Tx: %u/%u\n", ( unsigned ) ulRxWindowLength, ( unsigned ) ulTxWindowLength ) ); } pxWindow->xSize.ulRxWindowLength = ulRxWindowLength; pxWindow->xSize.ulTxWindowLength = ulTxWindowLength; vTCPWindowInit( pxWindow, ulAckNumber, ulSequenceNumber, ulMSS ); } /*-----------------------------------------------------------*/ /** * @brief Initialise a TCP window. * * @param[in] pxWindow: The window to be initialised. * @param[in] ulAckNumber: The number of the first ACK. * @param[in] ulSequenceNumber: The first sequence number. * @param[in] ulMSS: The MSS of the connection. */ void vTCPWindowInit( TCPWindow_t * pxWindow, uint32_t ulAckNumber, uint32_t ulSequenceNumber, uint32_t ulMSS ) { const int32_t l500ms = 500; pxWindow->u.ulFlags = 0U; pxWindow->u.bits.bHasInit = pdTRUE_UNSIGNED; if( ulMSS != 0U ) { if( pxWindow->usMSSInit != 0U ) { pxWindow->usMSSInit = ( uint16_t ) ulMSS; } if( ( ulMSS < ( uint32_t ) pxWindow->usMSS ) || ( pxWindow->usMSS == 0U ) ) { pxWindow->xSize.ulRxWindowLength = ( pxWindow->xSize.ulRxWindowLength / ulMSS ) * ulMSS; pxWindow->usMSS = ( uint16_t ) ulMSS; } } #if ( ipconfigUSE_TCP_WIN == 0 ) { pxWindow->xTxSegment.lMaxLength = ( int32_t ) pxWindow->usMSS; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*Start with a timeout of 2 * 500 ms (1 sec). */ pxWindow->lSRTT = l500ms; /* Just for logging, to print relative sequence numbers. */ pxWindow->rx.ulFirstSequenceNumber = ulAckNumber; /* The segment asked for in the next transmission. */ pxWindow->rx.ulCurrentSequenceNumber = ulAckNumber; /* The right-hand side of the receive window. */ pxWindow->rx.ulHighestSequenceNumber = ulAckNumber; pxWindow->tx.ulFirstSequenceNumber = ulSequenceNumber; /* The segment asked for in next transmission. */ pxWindow->tx.ulCurrentSequenceNumber = ulSequenceNumber; /* The sequence number given to the next outgoing byte to be added is * maintained by lTCPWindowTxAdd(). */ pxWindow->ulNextTxSequenceNumber = ulSequenceNumber; /* The right-hand side of the transmit window. */ pxWindow->tx.ulHighestSequenceNumber = ulSequenceNumber; pxWindow->ulOurSequenceNumber = ulSequenceNumber; } /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Free the space occupied by the pool of segment descriptors, normally never used */ void vTCPSegmentCleanup( void ) { /* Free and clear the TCP segments pointer. This function should only be called * once FreeRTOS+TCP will no longer be used. No thread-safety is provided for this * function. */ if( xTCPSegments != NULL ) { vPortFreeLarge( xTCPSegments ); xTCPSegments = NULL; } } #endif /* ipconfgiUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ /*============================================================================= * * ###### # # * # # # # * # # # # * # # #### * ###### ## * # ## #### * # # # # * # # # # * ### ## # # * Rx functions * *=============================================================================*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief A expected segment has been received, see if there is overlap with earlier segments. * * @param[in] pxWindow: The descriptor of the TCP sliding windows. * @param[in] ulSequenceNumber: The sequence number of the segment that was received. * @param[in] ulLength: The number of bytes that were received. * * @return The first segment descriptor involved, or NULL when no matching descriptor was found. */ static TCPSegment_t * xTCPWindowRxConfirm( const TCPWindow_t * pxWindow, uint32_t ulSequenceNumber, uint32_t ulLength ) { TCPSegment_t * pxBest = NULL; const ListItem_t * pxIterator; uint32_t ulNextSequenceNumber = ulSequenceNumber + ulLength; /* 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 ListItem_t * pxEnd = ( ( const ListItem_t * ) &( pxWindow->xRxSegments.xListEnd ) ); TCPSegment_t * pxSegment; /* A segment has been received with sequence number 'ulSequenceNumber', * where 'ulCurrentSequenceNumber == ulSequenceNumber', which means that * exactly this segment was expected. xTCPWindowRxConfirm() will check if * there is already another segment with a sequence number between (ulSequenceNumber) * and (ulSequenceNumber+ulLength). Normally none will be found, because * the next RX segment should have a sequence number equal to * '(ulSequenceNumber+ulLength)'. */ /* Iterate through all RX segments that are stored: */ for( pxIterator = listGET_NEXT( pxEnd ); pxIterator != pxEnd; pxIterator = listGET_NEXT( pxIterator ) ) { pxSegment = ( ( TCPSegment_t * ) listGET_LIST_ITEM_OWNER( pxIterator ) ); /* And see if there is a segment for which: * 'ulSequenceNumber' <= 'pxSegment->ulSequenceNumber' < 'ulNextSequenceNumber' * If there are more matching segments, the one with the lowest sequence number * shall be taken */ if( ( xSequenceGreaterThanOrEqual( pxSegment->ulSequenceNumber, ulSequenceNumber ) != 0 ) && ( xSequenceLessThan( pxSegment->ulSequenceNumber, ulNextSequenceNumber ) != 0 ) ) { if( ( pxBest == NULL ) || ( xSequenceLessThan( pxSegment->ulSequenceNumber, pxBest->ulSequenceNumber ) != 0 ) ) { pxBest = pxSegment; } } } if( ( pxBest != NULL ) && ( ( pxBest->ulSequenceNumber != ulSequenceNumber ) || ( pxBest->lDataLength != ( int32_t ) ulLength ) ) ) { FreeRTOS_debug_printf( ( "xTCPWindowRxConfirm[%u]: search %u (+%u=%u) found %u (+%d=%u)\n", pxWindow->usPeerPortNumber, ( unsigned ) ( ulSequenceNumber - pxWindow->rx.ulFirstSequenceNumber ), ( unsigned ) ulLength, ( unsigned ) ( ulSequenceNumber + ulLength - pxWindow->rx.ulFirstSequenceNumber ), ( unsigned ) ( pxBest->ulSequenceNumber - pxWindow->rx.ulFirstSequenceNumber ), ( int ) pxBest->lDataLength, ( unsigned ) ( pxBest->ulSequenceNumber + ( ( uint32_t ) pxBest->lDataLength ) - pxWindow->rx.ulFirstSequenceNumber ) ) ); } return pxBest; } #endif /* ipconfgiUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Data has been received with the correct ( expected ) sequence number. * It can be added to the RX stream buffer. * @param[in] pxWindow: The TCP sliding window data of the socket. * @param[in] ulLength: The number of bytes that can be added. */ static void prvTCPWindowRx_ExpectedRX( TCPWindow_t * pxWindow, uint32_t ulLength ) { uint32_t ulSequenceNumber = pxWindow->rx.ulCurrentSequenceNumber; uint32_t ulCurrentSequenceNumber = ulSequenceNumber + ulLength; if( listCURRENT_LIST_LENGTH( &( pxWindow->xRxSegments ) ) != 0U ) { uint32_t ulSavedSequenceNumber = ulCurrentSequenceNumber; TCPSegment_t * pxFound; /* Clean up all sequence received between ulSequenceNumber and ulSequenceNumber + ulLength since they are duplicated. * If the server is forced to retransmit packets several time in a row it might send a batch of concatenated packet for speed. * So we cannot rely on the packets between ulSequenceNumber and ulSequenceNumber + ulLength to be sequential and it is better to just * clean them out. */ do { pxFound = xTCPWindowRxConfirm( pxWindow, ulSequenceNumber, ulLength ); if( pxFound != NULL ) { /* Remove it because it will be passed to user directly. */ vTCPWindowFree( pxFound ); } } while( pxFound != NULL ); /* Check for following segments that are already in the * queue and increment ulCurrentSequenceNumber. */ for( ; ; ) { pxFound = xTCPWindowRxFind( pxWindow, ulCurrentSequenceNumber ); if( pxFound == NULL ) { break; } ulCurrentSequenceNumber += ( uint32_t ) pxFound->lDataLength; /* As all packet below this one have been passed to the * user it can be discarded. */ vTCPWindowFree( pxFound ); } if( ulSavedSequenceNumber != ulCurrentSequenceNumber ) { /* After the current data-package, there is more data * to be popped. */ pxWindow->ulUserDataLength = ulCurrentSequenceNumber - ulSavedSequenceNumber; if( xTCPWindowLoggingLevel >= 1 ) { FreeRTOS_debug_printf( ( "lTCPWindowRxCheck[%u,%u]: retran %u (Found %u bytes at %u cnt %d)\n", pxWindow->usPeerPortNumber, pxWindow->usOurPortNumber, ( unsigned ) ( ulSequenceNumber - pxWindow->rx.ulFirstSequenceNumber ), ( unsigned ) pxWindow->ulUserDataLength, ( unsigned ) ( ulSavedSequenceNumber - pxWindow->rx.ulFirstSequenceNumber ), ( int ) listCURRENT_LIST_LENGTH( &pxWindow->xRxSegments ) ) ); } } } pxWindow->rx.ulCurrentSequenceNumber = ulCurrentSequenceNumber; } #endif /* ipconfgiUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Data has been received with a non-expected sequence number. * This function will check if the RX data can be accepted. * @param[in] pxWindow: The TCP sliding window data of the socket. * @param[in] ulSequenceNumber: The sequence number at which the data should be placed. * @param[in] ulLength: The number of bytes that can be added. * @return Return -1 if the data must be refused, otherwise it returns the * offset ( from the head ) at which the data can be placed. */ static int32_t prvTCPWindowRx_UnexpectedRX( TCPWindow_t * pxWindow, uint32_t ulSequenceNumber, uint32_t ulLength ) { int32_t lReturn = -1; uint32_t ulLast = ulSequenceNumber + ulLength; uint32_t ulCurrentSequenceNumber = pxWindow->rx.ulCurrentSequenceNumber; const TCPSegment_t * pxFound; /* See if there is more data in a contiguous block to make the * SACK describe a longer range of data. */ /* TODO: SACK's may also be delayed for a short period * This is useful because subsequent packets will be SACK'd with * single one message */ for( ; ; ) { pxFound = xTCPWindowRxFind( pxWindow, ulLast ); if( pxFound == NULL ) { break; } ulLast += ( uint32_t ) pxFound->lDataLength; } if( xTCPWindowLoggingLevel >= 1 ) { FreeRTOS_debug_printf( ( "lTCPWindowRxCheck[%d,%d]: seqnr %u exp %u (dist %d) SACK to %u\n", ( int ) pxWindow->usPeerPortNumber, ( int ) pxWindow->usOurPortNumber, ( unsigned ) ( ulSequenceNumber - pxWindow->rx.ulFirstSequenceNumber ), ( unsigned ) ( ulCurrentSequenceNumber - pxWindow->rx.ulFirstSequenceNumber ), ( int ) ( ulSequenceNumber - ulCurrentSequenceNumber ), /* want this signed */ ( unsigned ) ( ulLast - pxWindow->rx.ulFirstSequenceNumber ) ) ); } /* Now prepare the SACK message. * Code OPTION_CODE_SINGLE_SACK already in network byte order. */ pxWindow->ulOptionsData[ 0 ] = OPTION_CODE_SINGLE_SACK; /* First sequence number that we received. */ pxWindow->ulOptionsData[ 1 ] = FreeRTOS_htonl( ulSequenceNumber ); /* Last + 1 */ pxWindow->ulOptionsData[ 2 ] = FreeRTOS_htonl( ulLast ); /* Which make 12 (3*4) option bytes. */ pxWindow->ucOptionLength = ( uint8_t ) ( 3U * sizeof( pxWindow->ulOptionsData[ 0 ] ) ); pxFound = xTCPWindowRxFind( pxWindow, ulSequenceNumber ); if( pxFound != NULL ) { /* This out-of-sequence packet has been received for a * second time. It is already stored but do send a SACK * again. */ /* A negative value will be returned to indicate than error. */ } else { pxFound = xTCPWindowRxNew( pxWindow, ulSequenceNumber, ( int32_t ) ulLength ); if( pxFound == NULL ) { /* Can not send a SACK, because the segment cannot be * stored. */ pxWindow->ucOptionLength = 0U; /* Needs to be stored but there is no segment * available. A negative value will be returned. */ } else { uint32_t ulIntermediateResult; if( xTCPWindowLoggingLevel != 0 ) { FreeRTOS_debug_printf( ( "lTCPWindowRxCheck[%u,%u]: seqnr %u (cnt %u)\n", pxWindow->usPeerPortNumber, pxWindow->usOurPortNumber, ( unsigned ) ( ulSequenceNumber - pxWindow->rx.ulFirstSequenceNumber ), ( unsigned ) listCURRENT_LIST_LENGTH( &pxWindow->xRxSegments ) ) ); FreeRTOS_flush_logging(); } /* Return a positive value. The packet may be accepted * and stored but an earlier packet is still missing. */ ulIntermediateResult = ulSequenceNumber - ulCurrentSequenceNumber; lReturn = ( int32_t ) ulIntermediateResult; } } return lReturn; } #endif /* ipconfgiUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Check what to do with a new incoming packet: store or ignore. * * @param[in] pxWindow: The descriptor of the TCP sliding windows. * @param[in] ulSequenceNumber: The sequence number of the packet received. * @param[in] ulLength: The number of bytes received. * @param[in] ulSpace: The available space in the RX stream buffer. * @param[out] pulSkipCount: the number of bytes to skip in the receive buffer. * * @return 0 or positive value indicating the offset at which the packet is to * be stored, -1 if the packet is to be ignored. */ int32_t lTCPWindowRxCheck( TCPWindow_t * pxWindow, uint32_t ulSequenceNumber, uint32_t ulLength, uint32_t ulSpace, uint32_t * pulSkipCount ) { uint32_t ulCurrentSequenceNumber; uint32_t ulIntermediateResult; int32_t lReturn = -1; int32_t lStartDistance; int32_t lLastDistance; uint32_t ulLast; uint32_t ulRxSequenceNumber = ulSequenceNumber; uint32_t ulRxLength = ulLength; /* If lTCPWindowRxCheck( ) returns == 0, the packet will be passed * directly to user (segment is expected). If it returns a positive * number, an earlier packet is missing, but this packet may be stored. * If negative, the packet has already been stored, or it is out-of-order, * or there is not enough space. * * As a side-effect, pxWindow->ulUserDataLength will get set to non-zero, * if more Rx data may be passed to the user after this packet. */ /* Only in an exceptional case, where a packet starts before * ulCurrentSequenceNumber, and ends after it, the skip-count * will be set. See below. */ *( pulSkipCount ) = 0U; ulCurrentSequenceNumber = pxWindow->rx.ulCurrentSequenceNumber; ulLast = ulRxSequenceNumber + ulRxLength; ulIntermediateResult = ulLast - ulCurrentSequenceNumber; /* The cast from unsigned long to signed long is on purpose. */ lLastDistance = ( int32_t ) ulIntermediateResult; ulIntermediateResult = ulRxSequenceNumber - ulCurrentSequenceNumber; lStartDistance = ( int32_t ) ulIntermediateResult; if( ( lStartDistance < 0 ) && ( lLastDistance > 0 ) ) { FreeRTOS_debug_printf( ( "lTCPWindowRxCheck: Received +%u bytes for %u, only using %d\n", ( unsigned ) ulRxLength, ( unsigned ) ( ulRxSequenceNumber - pxWindow->rx.ulFirstSequenceNumber ), ( int ) lLastDistance ) ); /* Increase the sequence number, decrease the length. */ ulRxSequenceNumber += ( uint32_t ) ( -lStartDistance ); ulRxLength += ( uint32_t ) lStartDistance; /* Tell the caller that the first 'pulSkipCount' bytes don't * need to be stored. */ *( pulSkipCount ) = ( uint32_t ) ( -lStartDistance ); } /* For Selective Ack (SACK), used when out-of-sequence data come in. */ pxWindow->ucOptionLength = 0U; /* Non-zero if TCP-windows contains data which must be popped. */ pxWindow->ulUserDataLength = 0U; if( ulCurrentSequenceNumber == ulRxSequenceNumber ) { /* This is the packet with the lowest sequence number we're waiting * for. It can be passed directly to the rx stream. */ if( ulRxLength > ulSpace ) { FreeRTOS_debug_printf( ( "lTCPWindowRxCheck: Refuse %u bytes, due to lack of space (%u)\n", ( unsigned ) ulRxLength, ( unsigned ) ulSpace ) ); } else { /* Packet was expected, may be passed directly to the socket * buffer or application. Store the packet at offset 0. */ prvTCPWindowRx_ExpectedRX( pxWindow, ulRxLength ); lReturn = 0; } } else if( ulCurrentSequenceNumber == ( ulRxSequenceNumber + 1U ) ) { /* Looks like a TCP keep-alive message. Do not accept/store Rx data * ulUserDataLength = 0. Not packet out-of-sync. Just reply to it. */ } else { /* The packet is not the one expected. See if it falls within the Rx * window so it can be stored. */ /* An "out-of-sequence" segment was received, must have missed one. * Prepare a SACK (Selective ACK). */ if( lLastDistance <= 0 ) { /* An earlier packet has been received, must be a retransmission of a * packet that has been accepted already. No need to send out a * Selective ACK (SACK). */ } else if( lLastDistance > ( int32_t ) ulSpace ) { /* The new segment is ahead of rx.ulCurrentSequenceNumber. The * sequence number of this packet is too far ahead, ignore it. */ FreeRTOS_debug_printf( ( "lTCPWindowRxCheck: Refuse %d+%u bytes, due to lack of space (%u)\n", ( int ) lLastDistance, ( unsigned ) ulRxLength, ( unsigned ) ulSpace ) ); } else { lReturn = prvTCPWindowRx_UnexpectedRX( pxWindow, ulRxSequenceNumber, ulRxLength ); } } return lReturn; } #endif /* ipconfgiUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ /*============================================================================= * * ######### # # * # # # # # * # # # * # #### * # ## * # #### * # # # * # # # * ##### # # * * Tx functions * *=============================================================================*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Increment the position in a circular buffer of size 'lMax'. * * @param[in] lPosition: The current index in the buffer. * @param[in] lMax: The total number of items in this buffer. * @param[in] lCount: The number of bytes that must be advanced. * * @return The new incremented position, or "( lPosition + lCount ) % lMax". */ static int32_t lTCPIncrementTxPosition( int32_t lPosition, int32_t lMax, int32_t lCount ) { int32_t lReturn; /* +TCP stores data in circular buffers. Calculate the next position to * store. */ lReturn = lPosition + lCount; if( lReturn >= lMax ) { lReturn -= lMax; } return lReturn; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Adding data to a segment that was already in the TX queue. It * will be filled-up to a maximum of MSS ( maximum segment size ). * * @param[in] pxWindow: The descriptor of the TCP sliding windows. * @param[in] pxSegment: The TX segment with the highest sequence number, * i.e. the "front segment". * @param[in] lBytesLeft: The number of bytes that must be added. * * @return lToWrite: the number of bytes added to the segment. */ static int32_t prvTCPWindowTxAdd_FrontSegment( TCPWindow_t * pxWindow, TCPSegment_t * pxSegment, int32_t lBytesLeft ) { int32_t lToWrite = FreeRTOS_min_int32( lBytesLeft, pxSegment->lMaxLength - pxSegment->lDataLength ); pxSegment->lDataLength += lToWrite; if( pxSegment->lDataLength >= pxSegment->lMaxLength ) { /* This segment is full, don't add more bytes. */ pxWindow->pxHeadSegment = NULL; } /* ulNextTxSequenceNumber is the sequence number of the next byte to * be stored for transmission. */ pxWindow->ulNextTxSequenceNumber += ( uint32_t ) lToWrite; /* Some detailed logging, for those who're interested. */ if( ( xTCPWindowLoggingLevel >= 2 ) && ipconfigTCP_MAY_LOG_PORT( pxWindow->usOurPortNumber ) ) { FreeRTOS_debug_printf( ( "lTCPWindowTxAdd: Add %4d bytes for seqNr %u len %4d (nxt %u) pos %d\n", ( int ) lBytesLeft, ( unsigned ) ( pxSegment->ulSequenceNumber - pxWindow->tx.ulFirstSequenceNumber ), ( int ) pxSegment->lDataLength, ( unsigned ) ( pxWindow->ulNextTxSequenceNumber - pxWindow->tx.ulFirstSequenceNumber ), ( int ) pxSegment->lStreamPos ) ); FreeRTOS_flush_logging(); } return lToWrite; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Will add data to be transmitted to the front of the segment fifo. * * @param[in] pxWindow: The descriptor of the TCP sliding windows. * @param[in] ulLength: The number of bytes that will be sent. * @param[in] lPosition: The index in the TX stream buffer. * @param[in] lMax: The size of the ( circular ) TX stream buffer. * * @return The number of bytes added to the sliding window for transmission. * */ int32_t lTCPWindowTxAdd( TCPWindow_t * pxWindow, uint32_t ulLength, int32_t lPosition, int32_t lMax ) { int32_t lBytesLeft = ( int32_t ) ulLength; int32_t lToWrite; int32_t lDone = 0; int32_t lBufferIndex = lPosition; TCPSegment_t * pxSegment = pxWindow->pxHeadSegment; /* Puts a message in the Tx-window (after buffer size has been * verified). */ if( ( pxSegment != NULL ) && ( pxSegment->lDataLength < pxSegment->lMaxLength ) && ( pxSegment->u.bits.bOutstanding == pdFALSE_UNSIGNED ) && ( pxSegment->lDataLength != 0 ) ) { lToWrite = prvTCPWindowTxAdd_FrontSegment( pxWindow, pxSegment, lBytesLeft ); lBytesLeft -= lToWrite; /* Increased the return value. */ lDone += lToWrite; /* Calculate the next position in the circular data buffer, knowing * its maximum length 'lMax'. */ lBufferIndex = lTCPIncrementTxPosition( lBufferIndex, lMax, lToWrite ); } while( lBytesLeft > 0 ) { /* The current transmission segment is full, create new segments as * needed. */ pxSegment = xTCPWindowTxNew( pxWindow, pxWindow->ulNextTxSequenceNumber, ( int32_t ) pxWindow->usMSS ); if( pxSegment != NULL ) { /* Store as many as needed, but no more than the maximum * (MSS). */ lToWrite = FreeRTOS_min_int32( lBytesLeft, pxSegment->lMaxLength ); pxSegment->lDataLength = lToWrite; pxSegment->lStreamPos = lBufferIndex; lBytesLeft -= lToWrite; lBufferIndex = lTCPIncrementTxPosition( lBufferIndex, lMax, lToWrite ); pxWindow->ulNextTxSequenceNumber += ( uint32_t ) lToWrite; lDone += lToWrite; /* Link this segment in the Tx-Queue. */ vListInsertFifo( &( pxWindow->xTxQueue ), &( pxSegment->xQueueItem ) ); /* Let 'pxHeadSegment' point to this segment if there is still * space. */ if( pxSegment->lDataLength < pxSegment->lMaxLength ) { pxWindow->pxHeadSegment = pxSegment; } else { pxWindow->pxHeadSegment = NULL; } } else { /* A sever situation: running out of segments for transmission. * No more data can be sent at the moment. */ if( lDone != 0 ) { FreeRTOS_debug_printf( ( "lTCPWindowTxAdd: Sorry all buffers full (cancel %d bytes)\n", ( int ) lBytesLeft ) ); } break; } } return lDone; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Returns true if there are no more outstanding TX segments. * * @param[in] pxWindow: The descriptor of the TCP sliding windows. * * @return pdTRUE if there are no more outstanding Tx segments, else pdFALSE. */ BaseType_t xTCPWindowTxDone( const TCPWindow_t * pxWindow ) { return listLIST_IS_EMPTY( ( &pxWindow->xTxSegments ) ); } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Find out if the peer is able to receive more data. * * @param[in] pxWindow: The descriptor of the TCP sliding windows. * @param[in] ulWindowSize: The number of bytes in this segment. * * @return True if the peer has space in it window to receive more data. */ static BaseType_t prvTCPWindowTxHasSpace( TCPWindow_t const * pxWindow, uint32_t ulWindowSize ) { uint32_t ulTxOutstanding; BaseType_t xHasSpace; const TCPSegment_t * pxSegment; uint32_t ulNettSize; /* This function will look if there is new transmission data. It will * return true if there is data to be sent. */ pxSegment = xTCPWindowPeekHead( &( pxWindow->xTxQueue ) ); if( pxSegment == NULL ) { xHasSpace = pdFALSE; } else { /* How much data is outstanding, i.e. how much data has been sent * but not yet acknowledged ? */ if( pxWindow->tx.ulHighestSequenceNumber >= pxWindow->tx.ulCurrentSequenceNumber ) { ulTxOutstanding = pxWindow->tx.ulHighestSequenceNumber - pxWindow->tx.ulCurrentSequenceNumber; } else { ulTxOutstanding = 0U; } /* Subtract this from the peer's space. */ ulNettSize = ulWindowSize - FreeRTOS_min_uint32( ulWindowSize, ulTxOutstanding ); /* See if the next segment may be sent. */ if( ulNettSize >= ( uint32_t ) pxSegment->lDataLength ) { xHasSpace = pdTRUE; } else { xHasSpace = pdFALSE; } /* If 'xHasSpace', it looks like the peer has at least space for 1 * more new segment of size MSS. xSize.ulTxWindowLength is the self-imposed * limitation of the transmission window (in case of many resends it * may be decreased). */ if( ( ulTxOutstanding != 0U ) && ( pxWindow->xSize.ulTxWindowLength < ( ulTxOutstanding + ( ( uint32_t ) pxSegment->lDataLength ) ) ) ) { xHasSpace = pdFALSE; } } return xHasSpace; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Returns true if there is TX data that can be sent right now. * * @param[in] pxWindow: The descriptor of the TCP sliding windows. * @param[in] ulWindowSize: The current size of the sliding RX window of the peer. * @param[out] pulDelay: The delay before the packet may be sent. * * @return pdTRUE if there is Tx data that can be sent, else pdFALSE. */ BaseType_t xTCPWindowTxHasData( TCPWindow_t const * pxWindow, uint32_t ulWindowSize, TickType_t * pulDelay ) { TCPSegment_t const * pxSegment; BaseType_t xReturn; TickType_t ulAge, ulMaxAge; *pulDelay = 0U; if( listLIST_IS_EMPTY( &pxWindow->xPriorityQueue ) == pdFALSE ) { /* No need to look at retransmissions or new transmission as long as * there are priority segments. *pulDelay equals zero, meaning it must * be sent out immediately. */ xReturn = pdTRUE; } else { pxSegment = xTCPWindowPeekHead( &( pxWindow->xWaitQueue ) ); if( pxSegment != NULL ) { uint32_t ulSRTT = ( uint32_t ) pxWindow->lSRTT; /* There is an outstanding segment, see if it is time to resend * it. */ ulAge = ulTimerGetAge( &pxSegment->xTransmitTimer ); /* After a packet has been sent for the first time, it will wait * '1 * ulSRTT' ms for an ACK. A second time it will wait '2 * ulSRTT' ms, * each time doubling the time-out */ ulMaxAge = ( ( uint32_t ) 1U << pxSegment->u.bits.ucTransmitCount ); ulMaxAge *= ulSRTT; if( ulMaxAge > ulAge ) { /* A segment must be sent after this amount of msecs */ *pulDelay = ulMaxAge - ulAge; } xReturn = pdTRUE; } else { /* No priority segment, no outstanding data, see if there is new * transmission data. */ pxSegment = xTCPWindowPeekHead( &pxWindow->xTxQueue ); /* See if it fits in the peer's reception window. */ if( pxSegment == NULL ) { xReturn = pdFALSE; } else if( prvTCPWindowTxHasSpace( pxWindow, ulWindowSize ) == pdFALSE ) { /* Too many outstanding messages. */ xReturn = pdFALSE; } else if( ( pxWindow->u.bits.bSendFullSize != pdFALSE_UNSIGNED ) && ( pxSegment->lDataLength < pxSegment->lMaxLength ) ) { /* 'bSendFullSize' is a special optimisation. If true, the * driver will only sent completely filled packets (of MSS * bytes). */ xReturn = pdFALSE; } else { xReturn = pdTRUE; } } } return xReturn; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Three type of queues are used for transmission: priority, waiting, and * the normal TX queue of unsent data. Message in the waiting queue will * be sent when their timer has expired. * @param[in] pxWindow: The descriptor of the TCP sliding windows. */ static TCPSegment_t * pxTCPWindowTx_GetWaitQueue( const TCPWindow_t * pxWindow ) { TCPSegment_t * pxSegment = xTCPWindowPeekHead( &( pxWindow->xWaitQueue ) ); if( pxSegment != NULL ) { /* Do check the timing. */ uint32_t ulMaxTime; ulMaxTime = ( ( uint32_t ) 1U ) << pxSegment->u.bits.ucTransmitCount; ulMaxTime *= ( uint32_t ) pxWindow->lSRTT; if( ulTimerGetAge( &pxSegment->xTransmitTimer ) > ulMaxTime ) { /* A normal (non-fast) retransmission. Move it from the * head of the waiting queue. */ pxSegment = xTCPWindowGetHead( &( pxWindow->xWaitQueue ) ); pxSegment->u.bits.ucDupAckCount = ( uint8_t ) pdFALSE_UNSIGNED; /* Some detailed logging. */ if( ( xTCPWindowLoggingLevel != 0 ) && ( ipconfigTCP_MAY_LOG_PORT( pxWindow->usOurPortNumber ) ) ) { FreeRTOS_debug_printf( ( "ulTCPWindowTxGet[%u,%u]: WaitQueue %d bytes for sequence number %u (0x%X)\n", pxWindow->usPeerPortNumber, pxWindow->usOurPortNumber, ( int ) pxSegment->lDataLength, ( unsigned ) ( pxSegment->ulSequenceNumber - pxWindow->tx.ulFirstSequenceNumber ), ( unsigned ) pxSegment->ulSequenceNumber ) ); FreeRTOS_flush_logging(); } } else { pxSegment = NULL; } } return pxSegment; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief See if there is a transmission in the normal TX queue. It is the * first time these data are being sent. After sending they will move * the waiting queue. * @param[in] pxWindow: The descriptor of the TCP sliding windows. * @param[in] ulWindowSize: The available space that the peer has in his * reception window. * @return Either a segment that has to be sent, or NULL. */ static TCPSegment_t * pxTCPWindowTx_GetTXQueue( TCPWindow_t * pxWindow, uint32_t ulWindowSize ) { TCPSegment_t * pxSegment = xTCPWindowPeekHead( &( pxWindow->xTxQueue ) ); if( pxSegment == NULL ) { /* No segments queued. */ } else if( ( pxWindow->u.bits.bSendFullSize != pdFALSE_UNSIGNED ) && ( pxSegment->lDataLength < pxSegment->lMaxLength ) ) { /* A segment has been queued but the driver waits until it * has a full size of MSS. */ pxSegment = NULL; } else if( prvTCPWindowTxHasSpace( pxWindow, ulWindowSize ) == pdFALSE ) { /* Peer has no more space at this moment. */ pxSegment = NULL; } else { /* pxSegment was just obtained with a peek function, * now remove it from of the Tx queue. */ pxSegment = xTCPWindowGetHead( &( pxWindow->xTxQueue ) ); /* Don't let pxHeadSegment point to this segment any more, * so no more data will be added. */ if( pxWindow->pxHeadSegment == pxSegment ) { pxWindow->pxHeadSegment = NULL; } /* pxWindow->tx.highest registers the highest sequence * number in our transmission window. */ pxWindow->tx.ulHighestSequenceNumber = pxSegment->ulSequenceNumber + ( ( uint32_t ) pxSegment->lDataLength ); /* ...and more detailed logging */ if( ( xTCPWindowLoggingLevel >= 2 ) && ( ipconfigTCP_MAY_LOG_PORT( pxWindow->usOurPortNumber ) ) ) { FreeRTOS_debug_printf( ( "ulTCPWindowTxGet[%u,%u]: XmitQueue %d bytes for sequence number %u (ws %u)\n", pxWindow->usPeerPortNumber, pxWindow->usOurPortNumber, ( int ) pxSegment->lDataLength, ( unsigned ) ( pxSegment->ulSequenceNumber - pxWindow->tx.ulFirstSequenceNumber ), ( unsigned ) ulWindowSize ) ); FreeRTOS_flush_logging(); } } return pxSegment; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Get data that can be transmitted right now. There are three types of * outstanding segments: Priority queue, Waiting queue, Normal TX queue. * * @param[in] pxWindow: The descriptor of the TCP sliding windows. * @param[in] ulWindowSize: The current size of the sliding RX window of the peer. * @param[out] plPosition: The index within the TX stream buffer of the first byte to be sent. * * @return The amount of data in bytes that can be transmitted right now. */ uint32_t ulTCPWindowTxGet( TCPWindow_t * pxWindow, uint32_t ulWindowSize, int32_t * plPosition ) { TCPSegment_t * pxSegment; uint32_t ulReturn = 0U; /* Fetches data to be sent-out now. * * Priority messages: segments with a resend need no check current sliding * window size. */ pxSegment = xTCPWindowGetHead( &( pxWindow->xPriorityQueue ) ); pxWindow->ulOurSequenceNumber = pxWindow->tx.ulHighestSequenceNumber; if( pxSegment != NULL ) { /* There is a priority segment. It doesn't need any checking for * space or timeouts. */ if( xTCPWindowLoggingLevel != 0 ) { FreeRTOS_debug_printf( ( "ulTCPWindowTxGet[%u,%u]: PrioQueue %d bytes for sequence number %u (ws %u)\n", pxWindow->usPeerPortNumber, pxWindow->usOurPortNumber, ( int ) pxSegment->lDataLength, ( unsigned ) ( pxSegment->ulSequenceNumber - pxWindow->tx.ulFirstSequenceNumber ), ( unsigned ) ulWindowSize ) ); FreeRTOS_flush_logging(); } } else { /* Waiting messages: outstanding messages with a running timer * neither check peer's reception window size because these packets * have been sent earlier. */ pxSegment = pxTCPWindowTx_GetWaitQueue( pxWindow ); if( pxSegment == NULL ) { /* New messages: sent-out for the first time. Check current * sliding window size of peer. */ pxSegment = pxTCPWindowTx_GetTXQueue( pxWindow, ulWindowSize ); } } /* See if it has already been determined to return 0. */ if( pxSegment != NULL ) { configASSERT( listLIST_ITEM_CONTAINER( &( pxSegment->xQueueItem ) ) == NULL ); /* Now that the segment will be transmitted, add it to the tail of * the waiting queue. */ vListInsertFifo( &pxWindow->xWaitQueue, &pxSegment->xQueueItem ); /* And mark it as outstanding. */ pxSegment->u.bits.bOutstanding = pdTRUE_UNSIGNED; /* Administer the transmit count, needed for fast * retransmissions. */ ( pxSegment->u.bits.ucTransmitCount )++; /* If there have been several retransmissions (4), decrease the * size of the transmission window to at most 2 times MSS. */ if( ( pxSegment->u.bits.ucTransmitCount == MAX_TRANSMIT_COUNT_USING_LARGE_WINDOW ) && ( pxWindow->xSize.ulTxWindowLength > ( 2U * ( ( uint32_t ) pxWindow->usMSS ) ) ) ) { uint16_t usMSS2 = pxWindow->usMSS * 2U; FreeRTOS_debug_printf( ( "ulTCPWindowTxGet[%u - %u]: Change Tx window: %u -> %u\n", pxWindow->usPeerPortNumber, pxWindow->usOurPortNumber, ( unsigned ) pxWindow->xSize.ulTxWindowLength, usMSS2 ) ); pxWindow->xSize.ulTxWindowLength = usMSS2; } /* Clear the transmit timer. */ vTCPTimerSet( &( pxSegment->xTransmitTimer ) ); pxWindow->ulOurSequenceNumber = pxSegment->ulSequenceNumber; /* Inform the caller where to find the data within the queue. */ *plPosition = pxSegment->lStreamPos; /* And return the length of the data segment */ ulReturn = ( uint32_t ) pxSegment->lDataLength; } return ulReturn; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Data has been sent, and an ACK has been received. Make an estimate * of the round-trip time, and calculate the new timeout for transmissions. * More explanation in a comment here below. * * @param[in] pxWindow: The descriptor of the TCP sliding windows. * @param[in] pxSegment: The segment that was just acknowledged. */ static void prvTCPWindowTxCheckAck_CalcSRTT( TCPWindow_t * pxWindow, const TCPSegment_t * pxSegment ) { int32_t mS = ( int32_t ) ulTimerGetAge( &( pxSegment->xTransmitTimer ) ); if( pxWindow->lSRTT >= mS ) { /* RTT becomes smaller: adapt slowly. */ pxWindow->lSRTT = ( ( winSRTT_DECREMENT_NEW * mS ) + ( winSRTT_DECREMENT_CURRENT * pxWindow->lSRTT ) ) / ( winSRTT_DECREMENT_NEW + winSRTT_DECREMENT_CURRENT ); } else { /* RTT becomes larger: adapt quicker */ pxWindow->lSRTT = ( ( winSRTT_INCREMENT_NEW * mS ) + ( winSRTT_INCREMENT_CURRENT * pxWindow->lSRTT ) ) / ( winSRTT_INCREMENT_NEW + winSRTT_INCREMENT_CURRENT ); } /* Cap to the minimum of 50ms. */ if( pxWindow->lSRTT < winSRTT_CAP_mS ) { pxWindow->lSRTT = winSRTT_CAP_mS; } } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief An acknowledgement or a selective ACK (SACK) was received. See if some outstanding data * may be removed from the transmission queue(s). All TX segments for which * ( ( ulSequenceNumber >= ulFirst ) && ( ulSequenceNumber < ulLast ) in a contiguous block. * Note that the segments are stored in xTxSegments in a strict sequential order. * * @param[in] pxWindow: The TCP-window object of the current connection. * @param[in] ulFirst: The sequence number of the first byte that was acknowledged. * @param[in] ulLast: The sequence number of the last byte ( minus one ) that was acknowledged. * * @return number of bytes that the tail of txStream may be advanced. */ static uint32_t prvTCPWindowTxCheckAck( TCPWindow_t * pxWindow, uint32_t ulFirst, uint32_t ulLast ) { uint32_t ulBytesConfirmed = 0U; uint32_t ulSequenceNumber = ulFirst; uint32_t ulDataLength; const ListItem_t * pxIterator; /* 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 ListItem_t * pxEnd = ( ( const ListItem_t * ) &( pxWindow->xTxSegments.xListEnd ) ); BaseType_t xDoUnlink; TCPSegment_t * pxSegment; /* An acknowledgement or a selective ACK (SACK) was received. See if some outstanding data * may be removed from the transmission queue(s). * All TX segments for which * ( ( ulSequenceNumber >= ulFirst ) && ( ulSequenceNumber < ulLast ) in a * contiguous block. Note that the segments are stored in xTxSegments in a * strict sequential order. */ /* SRTT[i] = (1-a) * SRTT[i-1] + a * RTT * * 0 < a < 1; usually a = 1/8 * * RTO = 2 * SRTT * * where: * RTT is Round Trip Time * SRTT is Smoothed RTT * RTO is Retransmit timeout * * A Smoothed RTT will increase quickly, but it is conservative when * becoming smaller. */ pxIterator = listGET_NEXT( pxEnd ); while( ( pxIterator != pxEnd ) && ( xSequenceLessThan( ulSequenceNumber, ulLast ) != 0 ) ) { xDoUnlink = pdFALSE; pxSegment = ( ( TCPSegment_t * ) listGET_LIST_ITEM_OWNER( pxIterator ) ); /* Move to the next item because the current item might get * removed. */ pxIterator = ( const ListItem_t * ) listGET_NEXT( pxIterator ); /* Continue if this segment does not fall within the ACK'd range. */ if( xSequenceGreaterThan( ulSequenceNumber, pxSegment->ulSequenceNumber ) != pdFALSE ) { continue; } /* Is it ready? */ if( ulSequenceNumber != pxSegment->ulSequenceNumber ) { /* coverity[break_stmt] : Break statement terminating the loop */ break; } ulDataLength = ( uint32_t ) pxSegment->lDataLength; if( pxSegment->u.bits.bAcked == pdFALSE_UNSIGNED ) { if( xSequenceGreaterThan( pxSegment->ulSequenceNumber + ( uint32_t ) ulDataLength, ulLast ) != pdFALSE ) { /* What happens? Only part of this segment was accepted, * probably due to WND limits * * AAAAAAA BBBBBBB << acked * aaaaaaa aaaa << sent */ #if ( ipconfigHAS_DEBUG_PRINTF != 0 ) { uint32_t ulFirstSeq = pxSegment->ulSequenceNumber - pxWindow->tx.ulFirstSequenceNumber; FreeRTOS_debug_printf( ( "prvTCPWindowTxCheckAck[%u.%u]: %u - %u Partial sequence number %u - %u\n", pxWindow->usPeerPortNumber, pxWindow->usOurPortNumber, ( unsigned ) ( ulFirstSeq - pxWindow->tx.ulFirstSequenceNumber ), ( unsigned ) ( ulLast - pxWindow->tx.ulFirstSequenceNumber ), ( unsigned ) ulFirstSeq, ( unsigned ) ( ulFirstSeq + ulDataLength ) ) ); } #endif /* ( ipconfigHAS_DEBUG_PRINTF != 0 ) */ break; } /* This segment is fully ACK'd, set the flag. */ pxSegment->u.bits.bAcked = pdTRUE; /* Calculate the RTT only if the segment was sent-out for the * first time and if this is the last ACK'd segment in a range. */ if( ( pxSegment->u.bits.ucTransmitCount == 1U ) && ( ( pxSegment->ulSequenceNumber + ulDataLength ) == ulLast ) ) { prvTCPWindowTxCheckAck_CalcSRTT( pxWindow, pxSegment ); } /* Unlink it from the 3 queues, but do not destroy it (yet). */ xDoUnlink = pdTRUE; } /* pxSegment->u.bits.bAcked is now true. Is it located at the left * side of the transmission queue? If so, it may be freed. */ if( ulSequenceNumber == pxWindow->tx.ulCurrentSequenceNumber ) { if( ( xTCPWindowLoggingLevel >= 2 ) && ( ipconfigTCP_MAY_LOG_PORT( pxWindow->usOurPortNumber ) ) ) { FreeRTOS_debug_printf( ( "prvTCPWindowTxCheckAck: %u - %u Ready sequence number %u\n", ( unsigned ) ( ulFirst - pxWindow->tx.ulFirstSequenceNumber ), ( unsigned ) ( ulLast - pxWindow->tx.ulFirstSequenceNumber ), ( unsigned ) ( pxSegment->ulSequenceNumber - pxWindow->tx.ulFirstSequenceNumber ) ) ); } /* Increase the left-hand value of the transmission window. */ pxWindow->tx.ulCurrentSequenceNumber += ulDataLength; /* This function will return the number of bytes that the tail * of txStream may be advanced. */ ulBytesConfirmed += ulDataLength; /* All segments below tx.ulCurrentSequenceNumber may be freed. */ vTCPWindowFree( pxSegment ); /* No need to unlink it any more. */ xDoUnlink = pdFALSE; } if( ( xDoUnlink != pdFALSE ) && ( listLIST_ITEM_CONTAINER( &( pxSegment->xQueueItem ) ) != NULL ) ) { /* Remove item from its queues. */ ( void ) uxListRemove( &pxSegment->xQueueItem ); } ulSequenceNumber += ulDataLength; } return ulBytesConfirmed; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief See if there are segments that need a fast retransmission. * * @param[in] pxWindow: The descriptor of the TCP sliding windows. * @param[in] ulFirst: The sequence number of the first segment that must be checked. * * @return The number of segments that need a fast retransmission. */ static uint32_t prvTCPWindowFastRetransmit( TCPWindow_t * pxWindow, uint32_t ulFirst ) { const ListItem_t * pxIterator; const ListItem_t * pxEnd; TCPSegment_t * pxSegment; uint32_t ulCount = 0U; /* A higher Tx block has been acknowledged. Now iterate through the * xWaitQueue to find a possible condition for a FAST retransmission. */ /* 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] */ pxEnd = ( ( const ListItem_t * ) &( pxWindow->xWaitQueue.xListEnd ) ); pxIterator = listGET_NEXT( pxEnd ); while( pxIterator != pxEnd ) { /* Get the owner, which is a TCP segment. */ pxSegment = ( ( TCPSegment_t * ) listGET_LIST_ITEM_OWNER( pxIterator ) ); /* Hop to the next item before the current gets unlinked. */ pxIterator = listGET_NEXT( pxIterator ); /* Fast retransmission: * When 3 packets with a higher sequence number have been acknowledged * by the peer, it is very unlikely a current packet will ever arrive. * It will be retransmitted far before the RTO. */ if( pxSegment->u.bits.bAcked == pdFALSE_UNSIGNED ) { if( xSequenceLessThan( pxSegment->ulSequenceNumber, ulFirst ) != pdFALSE ) { pxSegment->u.bits.ucDupAckCount++; if( pxSegment->u.bits.ucDupAckCount == DUPLICATE_ACKS_BEFORE_FAST_RETRANSMIT ) { pxSegment->u.bits.ucTransmitCount = ( uint8_t ) pdFALSE; /* Not clearing 'ucDupAckCount' yet as more SACK's might come in * which might lead to a second fast rexmit. */ if( ( xTCPWindowLoggingLevel >= 0 ) && ( ipconfigTCP_MAY_LOG_PORT( pxWindow->usOurPortNumber ) ) ) { FreeRTOS_debug_printf( ( "prvTCPWindowFastRetransmit: Requeue sequence number %u < %u\n", ( unsigned ) ( pxSegment->ulSequenceNumber - pxWindow->tx.ulFirstSequenceNumber ), ( unsigned ) ( ulFirst - pxWindow->tx.ulFirstSequenceNumber ) ) ); FreeRTOS_flush_logging(); } /* Remove it from xWaitQueue. */ ( void ) uxListRemove( &pxSegment->xQueueItem ); /* Add this segment to the priority queue so it gets * retransmitted immediately. */ vListInsertFifo( &( pxWindow->xPriorityQueue ), &( pxSegment->xQueueItem ) ); ulCount++; } } } } return ulCount; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Receive a normal ACK. * * @param[in] pxWindow: Window in which a data is receive. * @param[in] ulSequenceNumber: The sequence number of the ACK. * * @return The location where the packet should be added. */ uint32_t ulTCPWindowTxAck( TCPWindow_t * pxWindow, uint32_t ulSequenceNumber ) { uint32_t ulFirstSequence; uint32_t ulReturn; /* Receive a normal ACK. */ ulFirstSequence = pxWindow->tx.ulCurrentSequenceNumber; if( xSequenceLessThanOrEqual( ulSequenceNumber, ulFirstSequence ) != pdFALSE ) { ulReturn = 0U; } else { ulReturn = prvTCPWindowTxCheckAck( pxWindow, ulFirstSequence, ulSequenceNumber ); } return ulReturn; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #if ( ipconfigUSE_TCP_WIN == 1 ) /** * @brief Receive a SACK option. * * @param[in] pxWindow: Window in which the data is received. * @param[in] ulFirst: Index of starting position of options. * @param[in] ulLast: Index of end position of the options. * * @return returns the number of bytes which have been acked starting from * the head position. */ uint32_t ulTCPWindowTxSack( TCPWindow_t * pxWindow, uint32_t ulFirst, uint32_t ulLast ) { uint32_t ulAckCount; uint32_t ulCurrentSequenceNumber = pxWindow->tx.ulCurrentSequenceNumber; /* Receive a SACK option. */ ulAckCount = prvTCPWindowTxCheckAck( pxWindow, ulFirst, ulLast ); ( void ) prvTCPWindowFastRetransmit( pxWindow, ulFirst ); if( ( xTCPWindowLoggingLevel >= 1 ) && ( xSequenceGreaterThan( ulFirst, ulCurrentSequenceNumber ) != pdFALSE ) ) { FreeRTOS_debug_printf( ( "ulTCPWindowTxSack[%u,%u]: from %u to %u (ack = %u)\n", pxWindow->usPeerPortNumber, pxWindow->usOurPortNumber, ( unsigned ) ( ulFirst - pxWindow->tx.ulFirstSequenceNumber ), ( unsigned ) ( ulLast - pxWindow->tx.ulFirstSequenceNumber ), ( unsigned ) ( pxWindow->tx.ulCurrentSequenceNumber - pxWindow->tx.ulFirstSequenceNumber ) ) ); FreeRTOS_flush_logging(); } return ulAckCount; } #endif /* ipconfigUSE_TCP_WIN == 1 */ /*-----------------------------------------------------------*/ #endif /* ipconfigUSE_TCP == 1 */