xref: /FreeRTOS-Plus-TCP-v3.1.0/source/FreeRTOS_Tiny_TCP.c (revision 37bdfe577f3b728058de714e2e747d3c78803f26) 
1 /*
2  * FreeRTOS+TCP V3.1.0
3  * Copyright (C) 2022 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
4  *
5  * SPDX-License-Identifier: MIT
6  *
7  * Permission is hereby granted, free of charge, to any person obtaining a copy of
8  * this software and associated documentation files (the "Software"), to deal in
9  * the Software without restriction, including without limitation the rights to
10  * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
11  * the Software, and to permit persons to whom the Software is furnished to do so,
12  * subject to the following conditions:
13  *
14  * The above copyright notice and this permission notice shall be included in all
15  * copies or substantial portions of the Software.
16  *
17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
19  * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
20  * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
21  * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
22  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
23  *
24  * http://aws.amazon.com/freertos
25  * http://www.FreeRTOS.org
26  */
27 
28 /*=============================================================================
29  *
30  *       #####   #                      #####   ####  ######
31  *       # # #   #                      # # #  #    #  #    #
32  *         #                              #   #     #  #    #
33  *         #   ###   #####  #    #        #   #        #    #
34  *         #     #   #    # #    #        #   #        #####
35  *         #     #   #    # #    # ####   #   #        #
36  *         #     #   #    # #    #        #   #     #  #
37  *         #     #   #    #  ####         #    #    #  #
38  *        #### ##### #    #     #        ####   ####  ####
39  *                             #
40  *                          ###
41  * Tiny-TCP: TCP without sliding windows.
42  *
43  *=============================================================================*/
44 
45 /**
46  * @file FreeRTOS_TINY_TCP.c
47  * @brief Module which handles TCP when windowing is disabled
48  *
49  * In this module all ports and IP addresses and sequence numbers are
50  * being stored in host byte-order.
51  */
52 
53 
54 /* Standard includes. */
55 #include <stdint.h>
56 
57 /* FreeRTOS includes. */
58 #include "FreeRTOS.h"
59 #include "task.h"
60 
61 /* FreeRTOS+TCP includes. */
62 #include "FreeRTOS_IP.h"
63 #include "FreeRTOS_UDP_IP.h"
64 #include "FreeRTOS_Sockets.h"
65 #include "FreeRTOS_IP_Private.h"
66 
67 #if ( ipconfigUSE_TCP == 1 )
68 
69     #if ( ipconfigUSE_TCP_WIN == 0 )
70 
71 /** @brief Logging verbosity level. */
72         BaseType_t xTCPWindowLoggingLevel = 0;
73 
74         static portINLINE BaseType_t xSequenceGreaterThanOrEqual( uint32_t a,
75                                                                   uint32_t b );
76 
77 /**
78  * @brief Test if a>=b. This function is required since the sequence numbers can roll over.
79  *
80  * @param[in] a: The first sequence number.
81  * @param[in] b: The second sequence number.
82  *
83  * @return pdTRUE if a>=b, else pdFALSE.
84  */
85 
xSequenceGreaterThanOrEqual(uint32_t a,uint32_t b)86         static portINLINE BaseType_t xSequenceGreaterThanOrEqual( uint32_t a,
87                                                                   uint32_t b )
88         {
89             BaseType_t xResult = pdFALSE;
90 
91             /* Test if a >= b */
92             if( ( ( a - b ) & 0x80000000U ) == 0U )
93             {
94                 xResult = pdTRUE;
95             }
96 
97             return xResult;
98         }
99 
100         static portINLINE void vTCPTimerSet( TCPTimer_t * pxTimer );
101 
102 /**
103  * @brief Set the timer's "born" time.
104  *
105  * @param[in] pxTimer: The TCP timer.
106  */
vTCPTimerSet(TCPTimer_t * pxTimer)107         static portINLINE void vTCPTimerSet( TCPTimer_t * pxTimer )
108         {
109             pxTimer->uxBorn = xTaskGetTickCount();
110         }
111 /*-----------------------------------------------------------*/
112 
113         static portINLINE uint32_t ulTimerGetAge( const TCPTimer_t * pxTimer );
114 
115 /**
116  * @brief Get the timer age in milliseconds.
117  *
118  * @param[in] pxTimer: The timer whose age is to be fetched.
119  *
120  * @return The time in milliseconds since the timer was born.
121  */
ulTimerGetAge(const TCPTimer_t * pxTimer)122         static portINLINE uint32_t ulTimerGetAge( const TCPTimer_t * pxTimer )
123         {
124             TickType_t uxNow = xTaskGetTickCount();
125             TickType_t uxDiff = uxNow - pxTimer->uxBorn;
126 
127             return uxDiff * portTICK_PERIOD_MS;
128         }
129 /*-----------------------------------------------------------*/
130 
131 /**
132  * @brief Data was received at 'ulSequenceNumber'. See if it was expected
133  *        and if there is enough space to store the new data.
134  *
135  * @param[in] pxWindow: The window to be checked.
136  * @param[in] ulSequenceNumber: Sequence number of the data received.
137  * @param[in] ulLength: Length of the data received.
138  * @param[in] ulSpace: Space in the buffer.
139  *
140  * @return A 0 is returned if there is enough space and the sequence number is correct,
141  *         if not then a -1 is returned.
142  *
143  * @note if true may be passed directly to user (segment expected and window is empty).
144  *        But pxWindow->ackno should always be used to set "BUF->ackno".
145  */
lTCPWindowRxCheck(TCPWindow_t * pxWindow,uint32_t ulSequenceNumber,uint32_t ulLength,uint32_t ulSpace,uint32_t * pulSkipCount)146         int32_t lTCPWindowRxCheck( TCPWindow_t * pxWindow,
147                                    uint32_t ulSequenceNumber,
148                                    uint32_t ulLength,
149                                    uint32_t ulSpace,
150                                    uint32_t * pulSkipCount )
151         {
152             int32_t lReturn = -1;
153 
154             *pulSkipCount = 0;
155 
156             /* Data was received at 'ulSequenceNumber'.  See if it was expected
157              * and if there is enough space to store the new data. */
158             if( ( pxWindow->rx.ulCurrentSequenceNumber != ulSequenceNumber ) || ( ulSpace < ulLength ) )
159             {
160                 lReturn = -1;
161             }
162             else
163             {
164                 pxWindow->rx.ulCurrentSequenceNumber += ( uint32_t ) ulLength;
165                 lReturn = 0;
166             }
167 
168             return lReturn;
169         }
170     #endif /* ipconfigUSE_TCP_WIN == 0 */
171 /*-----------------------------------------------------------*/
172 
173     #if ( ipconfigUSE_TCP_WIN == 0 )
174 
175 /**
176  * @brief Add data to the Tx Window.
177  *
178  * @param[in] pxWindow: The window to which the data is to be added.
179  * @param[in] ulLength: The length of the data to be added.
180  * @param[in] lPosition: Position in the stream.
181  * @param[in] lMax: Size of the Tx stream.
182  *
183  * @return The data actually added.
184  */
lTCPWindowTxAdd(TCPWindow_t * pxWindow,uint32_t ulLength,int32_t lPosition,int32_t lMax)185         int32_t lTCPWindowTxAdd( TCPWindow_t * pxWindow,
186                                  uint32_t ulLength,
187                                  int32_t lPosition,
188                                  int32_t lMax )
189         {
190             TCPSegment_t * pxSegment = &( pxWindow->xTxSegment );
191             int32_t lResult;
192 
193             /* Data is being scheduled for transmission. */
194 
195             /* lMax would indicate the size of the txStream. */
196             ( void ) lMax;
197 
198             /* This is tiny TCP: there is only 1 segment for outgoing data.
199              * As long as 'lDataLength' is unequal to zero, the segment is still occupied. */
200             if( pxSegment->lDataLength > 0 )
201             {
202                 lResult = 0L;
203             }
204             else
205             {
206                 if( ulLength > ( uint32_t ) pxSegment->lMaxLength )
207                 {
208                     if( ( xTCPWindowLoggingLevel != 0 ) && ( ipconfigTCP_MAY_LOG_PORT( pxWindow->usOurPortNumber ) != pdFALSE ) )
209                     {
210                         FreeRTOS_debug_printf( ( "lTCPWindowTxAdd: can only store %u / %d bytes\n", ( unsigned ) ulLength, ( int ) pxSegment->lMaxLength ) );
211                     }
212 
213                     ulLength = ( uint32_t ) pxSegment->lMaxLength;
214                 }
215 
216                 if( ( xTCPWindowLoggingLevel != 0 ) && ( ipconfigTCP_MAY_LOG_PORT( pxWindow->usOurPortNumber ) != pdFALSE ) )
217                 {
218                     FreeRTOS_debug_printf( ( "lTCPWindowTxAdd: SeqNr %u (%u) Len %u\n",
219                                              ( unsigned ) ( pxWindow->ulNextTxSequenceNumber - pxWindow->tx.ulFirstSequenceNumber ),
220                                              ( unsigned ) ( pxWindow->tx.ulCurrentSequenceNumber - pxWindow->tx.ulFirstSequenceNumber ),
221                                              ( unsigned ) ulLength ) );
222                 }
223 
224                 /* The sequence number of the first byte in this packet. */
225                 pxSegment->ulSequenceNumber = pxWindow->ulNextTxSequenceNumber;
226                 pxSegment->lDataLength = ( int32_t ) ulLength;
227                 pxSegment->lStreamPos = lPosition;
228                 pxSegment->u.ulFlags = 0U;
229                 vTCPTimerSet( &( pxSegment->xTransmitTimer ) );
230 
231                 /* Increase the sequence number of the next data to be stored for
232                  * transmission. */
233                 pxWindow->ulNextTxSequenceNumber += ulLength;
234                 lResult = ( int32_t ) ulLength;
235             }
236 
237             return lResult;
238         }
239     #endif /* ipconfigUSE_TCP_WIN == 0 */
240 /*-----------------------------------------------------------*/
241 
242     #if ( ipconfigUSE_TCP_WIN == 0 )
243 
244 /**
245  * @brief Fetches data to be sent.
246  *
247  * @param[in] pxWindow: The window for the connection.
248  * @param[in] ulWindowSize: The size of the window.
249  * @param[out] plPosition: plPosition will point to a location with the circular data buffer: txStream.
250  *
251  * @return return the amount of data which may be sent along with the position in the txStream.
252  */
ulTCPWindowTxGet(TCPWindow_t * pxWindow,uint32_t ulWindowSize,int32_t * plPosition)253         uint32_t ulTCPWindowTxGet( TCPWindow_t * pxWindow,
254                                    uint32_t ulWindowSize,
255                                    int32_t * plPosition )
256         {
257             TCPSegment_t * pxSegment = &( pxWindow->xTxSegment );
258             uint32_t ulLength = ( uint32_t ) pxSegment->lDataLength;
259             uint32_t ulMaxTime;
260 
261             if( ulLength != 0U )
262             {
263                 /* _HT_ Still under investigation */
264                 ( void ) ulWindowSize;
265 
266                 if( pxSegment->u.bits.bOutstanding != pdFALSE_UNSIGNED )
267                 {
268                     /* As 'ucTransmitCount' has a minimum of 1, take 2 * RTT */
269                     ulMaxTime = ( ( uint32_t ) 1U ) << pxSegment->u.bits.ucTransmitCount;
270                     ulMaxTime *= ( uint32_t ) pxWindow->lSRTT;
271 
272                     if( ulTimerGetAge( &( pxSegment->xTransmitTimer ) ) < ulMaxTime )
273                     {
274                         ulLength = 0U;
275                     }
276                 }
277 
278                 if( ulLength != 0U )
279                 {
280                     pxSegment->u.bits.bOutstanding = pdTRUE_UNSIGNED;
281                     pxSegment->u.bits.ucTransmitCount++;
282                     vTCPTimerSet( &pxSegment->xTransmitTimer );
283                     pxWindow->ulOurSequenceNumber = pxSegment->ulSequenceNumber;
284                     *plPosition = pxSegment->lStreamPos;
285                 }
286             }
287 
288             return ulLength;
289         }
290     #endif /* ipconfigUSE_TCP_WIN == 0 */
291 /*-----------------------------------------------------------*/
292 
293     #if ( ipconfigUSE_TCP_WIN == 0 )
294 
295 /**
296  * @brief Has the transmission completed.
297  *
298  * @param[in] pxWindow: The window whose transmission window is to be checked.
299  *
300  * @return If there is no outstanding data then pdTRUE is returned,
301  *         else pdFALSE.
302  */
xTCPWindowTxDone(const TCPWindow_t * pxWindow)303         BaseType_t xTCPWindowTxDone( const TCPWindow_t * pxWindow )
304         {
305             BaseType_t xReturn;
306 
307             /* Has the outstanding data been sent because user wants to shutdown? */
308             if( pxWindow->xTxSegment.lDataLength == 0 )
309             {
310                 xReturn = pdTRUE;
311             }
312             else
313             {
314                 xReturn = pdFALSE;
315             }
316 
317             return xReturn;
318         }
319     #endif /* ipconfigUSE_TCP_WIN == 0 */
320 /*-----------------------------------------------------------*/
321 
322     #if ( ipconfigUSE_TCP_WIN == 0 )
323         static BaseType_t prvTCPWindowTxHasSpace( TCPWindow_t const * pxWindow,
324                                                   uint32_t ulWindowSize );
325 
326 /**
327  * @brief Check if the window has space for one message.
328  *
329  * @param[in] pxWindow: The window to be checked.
330  * @param[in] ulWindowSize: Size of the window.
331  *
332  * @return pdTRUE if the window has space, pdFALSE otherwise.
333  */
prvTCPWindowTxHasSpace(TCPWindow_t const * pxWindow,uint32_t ulWindowSize)334         static BaseType_t prvTCPWindowTxHasSpace( TCPWindow_t const * pxWindow,
335                                                   uint32_t ulWindowSize )
336         {
337             BaseType_t xReturn;
338 
339             if( ulWindowSize >= pxWindow->usMSSInit )
340             {
341                 xReturn = pdTRUE;
342             }
343             else
344             {
345                 xReturn = pdFALSE;
346             }
347 
348             return xReturn;
349         }
350     #endif /* ipconfigUSE_TCP_WIN == 0 */
351 /*-----------------------------------------------------------*/
352 
353     #if ( ipconfigUSE_TCP_WIN == 0 )
354 
355 /**
356  * @brief Check data to be sent and calculate the time period the process may sleep.
357  *
358  * @param[in] pxWindow: The window to be checked.
359  * @param[in] ulWindowSize: Size of the window.
360  * @param[out] pulDelay: The time period (in ticks) that the process may sleep.
361  *
362  * @return pdTRUE if the process should sleep or pdFALSE.
363  */
xTCPWindowTxHasData(TCPWindow_t const * pxWindow,uint32_t ulWindowSize,TickType_t * pulDelay)364         BaseType_t xTCPWindowTxHasData( TCPWindow_t const * pxWindow,
365                                         uint32_t ulWindowSize,
366                                         TickType_t * pulDelay )
367         {
368             TCPSegment_t const * pxSegment = &( pxWindow->xTxSegment );
369             BaseType_t xReturn;
370             TickType_t ulAge, ulMaxAge;
371 
372             /* Check data to be sent. */
373             *pulDelay = ( TickType_t ) 0;
374 
375             if( pxSegment->lDataLength == 0 )
376             {
377                 /* Got nothing to send right now. */
378                 xReturn = pdFALSE;
379             }
380             else
381             {
382                 if( pxSegment->u.bits.bOutstanding != pdFALSE_UNSIGNED )
383                 {
384                     ulAge = ulTimerGetAge( &pxSegment->xTransmitTimer );
385                     ulMaxAge = ( ( TickType_t ) 1U << pxSegment->u.bits.ucTransmitCount ) * ( ( uint32_t ) pxWindow->lSRTT );
386 
387                     if( ulMaxAge > ulAge )
388                     {
389                         *pulDelay = ulMaxAge - ulAge;
390                     }
391 
392                     xReturn = pdTRUE;
393                 }
394                 else if( prvTCPWindowTxHasSpace( pxWindow, ulWindowSize ) == pdFALSE )
395                 {
396                     /* Too many outstanding messages. */
397                     xReturn = pdFALSE;
398                 }
399                 else
400                 {
401                     xReturn = pdTRUE;
402                 }
403             }
404 
405             return xReturn;
406         }
407     #endif /* ipconfigUSE_TCP_WIN == 0 */
408 /*-----------------------------------------------------------*/
409 
410     #if ( ipconfigUSE_TCP_WIN == 0 )
411 
412 /**
413  * @brief Receive a normal ACK.
414  *
415  * @param[in] pxWindow: The window for this particular connection.
416  * @param[in] ulSequenceNumber: The sequence number of the packet.
417  *
418  * @return Number of bytes to send.
419  */
ulTCPWindowTxAck(TCPWindow_t * pxWindow,uint32_t ulSequenceNumber)420         uint32_t ulTCPWindowTxAck( TCPWindow_t * pxWindow,
421                                    uint32_t ulSequenceNumber )
422         {
423             TCPSegment_t * pxSegment = &( pxWindow->xTxSegment );
424             uint32_t ulDataLength = ( uint32_t ) pxSegment->lDataLength;
425 
426             /* Receive a normal ACK */
427 
428             if( ulDataLength != 0U )
429             {
430                 if( ulSequenceNumber < ( pxWindow->tx.ulCurrentSequenceNumber + ulDataLength ) )
431                 {
432                     if( ipconfigTCP_MAY_LOG_PORT( pxWindow->usOurPortNumber ) != pdFALSE )
433                     {
434                         FreeRTOS_debug_printf( ( "win_tx_ack: acked %u expc %u len %u\n",
435                                                  ( unsigned ) ( ulSequenceNumber - pxWindow->tx.ulFirstSequenceNumber ),
436                                                  ( unsigned ) ( pxWindow->tx.ulCurrentSequenceNumber - pxWindow->tx.ulFirstSequenceNumber ),
437                                                  ( unsigned ) ulDataLength ) );
438                     }
439 
440                     /* Nothing to send right now. */
441                     ulDataLength = 0U;
442                 }
443                 else
444                 {
445                     pxWindow->tx.ulCurrentSequenceNumber += ulDataLength;
446 
447                     if( ( xTCPWindowLoggingLevel != 0 ) && ( ipconfigTCP_MAY_LOG_PORT( pxWindow->usOurPortNumber ) != pdFALSE ) )
448                     {
449                         FreeRTOS_debug_printf( ( "win_tx_ack: acked seqnr %u len %u\n",
450                                                  ( unsigned ) ( ulSequenceNumber - pxWindow->tx.ulFirstSequenceNumber ),
451                                                  ( unsigned ) ulDataLength ) );
452                     }
453 
454                     pxSegment->lDataLength = 0;
455                 }
456             }
457 
458             return ulDataLength;
459         }
460     #endif /* ipconfigUSE_TCP_WIN == 0 */
461 /*-----------------------------------------------------------*/
462 
463     #if ( ipconfigUSE_TCP_WIN == 0 )
464 
465 /**
466  * @brief This function will be called as soon as a FIN is received to check
467  *        whether all transmit queues are empty or not.
468  *
469  * @param[in] pxWindow: The window to be checked.
470  *
471  * @return It will return true if there are no 'open' reception segments.
472  */
xTCPWindowRxEmpty(const TCPWindow_t * pxWindow)473         BaseType_t xTCPWindowRxEmpty( const TCPWindow_t * pxWindow )
474         {
475             /* Return true if 'ulCurrentSequenceNumber >= ulHighestSequenceNumber'
476              * 'ulCurrentSequenceNumber' is the highest sequence number stored,
477              * 'ulHighestSequenceNumber' is the highest sequence number seen. */
478             return xSequenceGreaterThanOrEqual( pxWindow->rx.ulCurrentSequenceNumber, pxWindow->rx.ulHighestSequenceNumber );
479         }
480     #endif /* ipconfigUSE_TCP_WIN == 0 */
481 /*-----------------------------------------------------------*/
482 
483     #if ( ipconfigUSE_TCP_WIN == 0 )
484 
485 /**
486  * @brief Destroy a window.
487  *
488  * @param[in] pxWindow: Pointer to the window to be destroyed.
489  *
490  * @return Always returns a NULL.
491  */
vTCPWindowDestroy(const TCPWindow_t * pxWindow)492         void vTCPWindowDestroy( const TCPWindow_t * pxWindow )
493         {
494             /* As in tiny TCP there are no shared segments descriptors, there is
495              * nothing to release. */
496             ( void ) pxWindow;
497         }
498     #endif /* ipconfigUSE_TCP_WIN == 0 */
499 /*-----------------------------------------------------------*/
500 
501 #endif /* ipconfigUSE_TCP == 1 */
502