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FreeRTOS_TCP_WIN.c
2505 lines (2118 loc) · 99.9 KB
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FreeRTOS_TCP_WIN.c
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/*
* FreeRTOS+TCP V2.3.3
* Copyright (C) 2020 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* 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 <stdint.h>
/* FreeRTOS includes. */
#include "FreeRTOS.h"
#include "task.h"
/* FreeRTOS+TCP includes. */
#include "FreeRTOS_UDP_IP.h"
#include "FreeRTOS_IP.h"
#include "FreeRTOS_Sockets.h"
#include "FreeRTOS_IP_Private.h"
#ifndef FREERTOS_DEFAULT_IP_CONFIG_H
#error "FreeRTOSIPConfigDefaults.h not included."
#endif
#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 50 /**< Cap in milliseconds. */
/**
* @brief Utility function to cast pointer of a type to pointer of type TCPSegment_t.
*
* @return The casted pointer.
*/
static portINLINE ipDECL_CAST_PTR_FUNC_FOR_TYPE( TCPSegment_t )
{
return ( TCPSegment_t * ) pvArgument;
}
#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 ( 0x0101050aUL )
#else
#define OPTION_CODE_SINGLE_SACK ( 0x0a050101UL )
#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 * const 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
/** @brief Logging verbosity level. */
BaseType_t xTCPWindowLoggingLevel = 0;
#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;
/* Test if a <= b
* Return true if the unsigned subtraction of (b-a) doesn't generate an
* arithmetic overflow. */
if( ( ( b - a ) & 0x80000000UL ) == 0UL )
{
xResult = pdTRUE;
}
else
{
xResult = pdFALSE;
}
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;
/* Test if a < b */
if( ( ( b - ( a + 1UL ) ) & 0x80000000UL ) == 0UL )
{
xResult = pdTRUE;
}
else
{
xResult = pdFALSE;
}
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;
/* Test if a > b */
if( ( ( a - ( b + 1UL ) ) & 0x80000000UL ) == 0UL )
{
xResult = pdTRUE;
}
else
{
xResult = pdFALSE;
}
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;
/* Test if a >= b */
if( ( ( a - b ) & 0x80000000UL ) == 0UL )
{
xResult = pdTRUE;
}
else
{
xResult = pdFALSE;
}
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->ulBorn = 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 )
{
return( ( xTaskGetTickCount() - ( ( TickType_t ) pxTimer->ulBorn ) ) * 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 * const 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() */
pxNewListItem->pxNext = ( struct xLIST_ITEM * configLIST_VOLATILE ) 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, xReturn;
/* Allocate space for 'xTCPSegments' and store them in 'xSegmentList'. */
vListInitialise( &xSegmentList );
xTCPSegments = ipCAST_PTR_TO_TYPE_PTR( 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. */
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. */
pxEnd = listGET_END_MARKER( &pxWindow->xRxSegments );
for( pxIterator = listGET_NEXT( pxEnd );
pxIterator != pxEnd;
pxIterator = listGET_NEXT( pxIterator ) )
{
pxSegment = ipCAST_PTR_TO_TYPE_PTR( 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 = ipCAST_PTR_TO_TYPE_PTR( 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, 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 %lu highest %lu (empty)\n",
( pxWindow->rx.ulCurrentSequenceNumber - pxWindow->rx.ulFirstSequenceNumber ),
( 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 = ipCAST_PTR_TO_TYPE_PTR( 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 = ipCAST_PTR_TO_TYPE_PTR( 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 = 0UL;
pxSegment->lDataLength = 0L;
pxSegment->u.ulFlags = 0UL;
/* 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 = ipCAST_PTR_TO_TYPE_PTR( 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: %lu/%lu\n",
ulRxWindowLength, 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 = 0UL;
pxWindow->u.bits.bHasInit = pdTRUE_UNSIGNED;
if( ulMSS != 0UL )
{
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;
const ListItem_t * pxEnd = listGET_END_MARKER( &pxWindow->xRxSegments );
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 = ipCAST_PTR_TO_TYPE_PTR( 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 %lu (+%ld=%lu) found %lu (+%ld=%lu)\n",
pxWindow->usPeerPortNumber,
ulSequenceNumber - pxWindow->rx.ulFirstSequenceNumber,
ulLength,
ulSequenceNumber + ulLength - pxWindow->rx.ulFirstSequenceNumber,
pxBest->ulSequenceNumber - pxWindow->rx.ulFirstSequenceNumber,
pxBest->lDataLength,
pxBest->ulSequenceNumber + ( ( uint32_t ) pxBest->lDataLength ) - pxWindow->rx.ulFirstSequenceNumber ) );
}
return pxBest;
}
#endif /* ipconfgiUSE_TCP_WIN == 1 */