[修改] 增加freeRTOS

1. 版本FreeRTOSv202212.01，命名为kernel；

kernel/FreeRTOS-Plus/Source/FreeRTOS-Plus-TCP/test/cbmc/proofs/TCP/prvTCPHandleState/Makefile.json

@@ -0,0 +1,62 @@
+#
+# FreeRTOS memory safety proofs with CBMC.
+# Copyright (C) 2022 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
+#
+
+{
+  "ENTRY": "TCPHandleState",
+  "TX_DRIVER":1,
+  "RX_MESSAGES":1,
+  "CBMCFLAGS":
+  [
+    "--unwind 1",
+    "--unwindset prvWinScaleFactor.0:2",
+    "--nondet-static"
+  ],
+  "OBJS":
+  [
+    "$(ENTRY)_harness.goto",
+    "$(FREERTOS_PLUS_TCP)/source/FreeRTOS_TCP_IP.goto",
+    "$(FREERTOS_PLUS_TCP)/source/FreeRTOS_IP.goto",
+    "$(FREERTOS_PLUS_TCP)/source/FreeRTOS_IP_Utils.goto",
+    "$(FREERTOS_PLUS_TCP)/source/FreeRTOS_IP_Timers.goto"
+  ],
+  "DEF":
+  [
+    "ipconfigZERO_COPY_TX_DRIVER={TX_DRIVER}",
+    "ipconfigUSE_LINKED_RX_MESSAGES={RX_MESSAGES}",
+    "FREERTOS_TCP_ENABLE_VERIFICATION"
+  ],
+  "INSTFLAGS":
+  [
+    "--remove-function-body prvTCPPrepareSend",
+    "--remove-function-body prvTCPReturnPacket"
+  ],
+  "INC":
+  [
+    "$(FREERTOS_PLUS_TCP)/test/cbmc/include"
+  ]
+}

kernel/FreeRTOS-Plus/Source/FreeRTOS-Plus-TCP/test/cbmc/proofs/TCP/prvTCPHandleState/README.md

@@ -0,0 +1,22 @@
+This is the memory safety proof for prvTCPHandleState.
+
+This proof is a work-in-progress.  Proof assumptions are described in
+the harness.  The proof also assumes the following functions are
+memory safe and have no side effects relevant to the memory safety of
+this function:
+
+* prvTCPPrepareSend (proved independently)
+* prvTCPReturnPacket (proved independently)
+
+* lTCPAddRxdata
+* lTCPWindowRxCheck
+* lTCPWindowTxAdd
+* ulTCPWindowTxAck
+* vTCPWindowInit
+* xTCPWindowRxEmpty
+* xTCPWindowTxDone
+
+* uxStreamBufferGet
+* vReleaseNetworkBufferAndDescriptor
+* vSocketWakeUpUser
+* xTaskGetTickCount

kernel/FreeRTOS-Plus/Source/FreeRTOS-Plus-TCP/test/cbmc/proofs/TCP/prvTCPHandleState/TCPHandleState_harness.c

@@ -0,0 +1,101 @@
+/*
+ * FreeRTOS memory safety proofs with CBMC.
+ * Copyright (C) 2022 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
+ */
+
+/* FreeRTOS includes. */
+#include "FreeRTOS.h"
+#include "queue.h"
+
+/* FreeRTOS+TCP includes. */
+#include "FreeRTOS_IP.h"
+#include "FreeRTOS_IP_Private.h"
+#include "FreeRTOS_TCP_IP.h"
+
+#include "../../utility/memory_assignments.c"
+
+/* Abstraction of xTaskGetCurrentTaskHandle */
+TaskHandle_t xTaskGetCurrentTaskHandle( void )
+{
+    static int xIsInit = 0;
+    static TaskHandle_t pxCurrentTCB;
+    TaskHandle_t xRandomTaskHandle; /* not initialized on purpose */
+
+    if( xIsInit == 0 )
+    {
+        pxCurrentTCB = xRandomTaskHandle;
+        xIsInit = 1;
+    }
+
+    return pxCurrentTCB;
+}
+
+/* This proof assumes that prvTCPPrepareSend and prvTCPReturnPacket are correct.
+ * These functions are proved to be correct separately. */
+
+BaseType_t publicTCPHandleState( FreeRTOS_Socket_t * pxSocket,
+                                 NetworkBufferDescriptor_t ** ppxNetworkBuffer );
+
+void harness()
+{
+    FreeRTOS_Socket_t * pxSocket = ensure_FreeRTOS_Socket_t_is_allocated();
+    size_t socketSize = sizeof( FreeRTOS_Socket_t );
+
+    if( ensure_memory_is_valid( pxSocket, socketSize ) )
+    {
+        /* ucOptionLength is the number of valid bytes in ulOptionsData[].
+         * ulOptionsData[] is initialized as uint32_t ulOptionsData[ipSIZE_TCP_OPTIONS/sizeof(uint32_t)].
+         * This assumption is required for a memcpy function that copies uxOptionsLength
+         * data from pxTCPHeader->ucOptdata to pxTCPWindow->ulOptionsData.*/
+        __CPROVER_assume( pxSocket->u.xTCP.xTCPWindow.ucOptionLength == sizeof( uint32_t ) * ipSIZE_TCP_OPTIONS / sizeof( uint32_t ) );
+        /* uxRxWinSize is initialized as size_t. This assumption is required to terminate `while(uxWinSize > 0xfffful)` loop.*/
+        __CPROVER_assume( pxSocket->u.xTCP.uxRxWinSize >= 0 && pxSocket->u.xTCP.uxRxWinSize <= sizeof( size_t ) );
+        /* uxRxWinSize is initialized as uint16_t. This assumption is required to terminate `while(uxWinSize > 0xfffful)` loop.*/
+        __CPROVER_assume( pxSocket->u.xTCP.usMSS == sizeof( uint16_t ) );
+
+        if( xIsCallingFromIPTask() == pdFALSE )
+        {
+            __CPROVER_assume( pxSocket->u.xTCP.bits.bPassQueued == pdFALSE_UNSIGNED );
+            __CPROVER_assume( pxSocket->u.xTCP.bits.bPassAccept == pdFALSE_UNSIGNED );
+        }
+    }
+
+    NetworkBufferDescriptor_t * pxNetworkBuffer = ensure_FreeRTOS_NetworkBuffer_is_allocated();
+    size_t bufferSize = sizeof( NetworkBufferDescriptor_t );
+
+    if( ensure_memory_is_valid( pxNetworkBuffer, bufferSize ) )
+    {
+        pxNetworkBuffer->pucEthernetBuffer = safeMalloc( sizeof( TCPPacket_t ) );
+    }
+
+    if( ensure_memory_is_valid( pxSocket, socketSize ) &&
+        ensure_memory_is_valid( pxNetworkBuffer, bufferSize ) &&
+        ensure_memory_is_valid( pxNetworkBuffer->pucEthernetBuffer, sizeof( TCPPacket_t ) ) &&
+        ensure_memory_is_valid( pxSocket->u.xTCP.pxPeerSocket, socketSize ) )
+    {
+        publicTCPHandleState( pxSocket, &pxNetworkBuffer );
+    }
+}

kernel/FreeRTOS-Plus/Source/FreeRTOS-Plus-TCP/test/cbmc/proofs/TCP/prvTCPPrepareSend/Makefile.json

@@ -0,0 +1,50 @@
+#
+# FreeRTOS memory safety proofs with CBMC.
+# Copyright (C) 2022 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
+#
+
+{
+  "ENTRY": "TCPPrepareSend",
+  "CBMCFLAGS":
+  [
+    "--unwind 1",
+    "--nondet-static"
+  ],
+  "OBJS":
+  [
+    "$(ENTRY)_harness.goto",
+    "$(FREERTOS_PLUS_TCP)/source/FreeRTOS_IP.goto",
+    "$(FREERTOS_PLUS_TCP)/source/FreeRTOS_TCP_IP.goto"
+  ],
+  "DEF":
+  [
+    "FREERTOS_TCP_ENABLE_VERIFICATION"
+  ],
+  "INC":
+  [
+    "$(FREERTOS_PLUS_TCP)/test/cbmc/include"
+  ]
+}

kernel/FreeRTOS-Plus/Source/FreeRTOS-Plus-TCP/test/cbmc/proofs/TCP/prvTCPPrepareSend/README.md

@@ -0,0 +1,15 @@
+This is the memory safety proof for prvTCPPrepareSend.
+
+This proof is a work-in-progress.  Proof assumptions are described in
+the harness.  The proof also assumes the following functions are
+memory safe and have no side effects relevant to the memory safety of
+this function:
+
+* ulTCPWindowTxGet
+* xTCPWindowTxDone
+
+* xTaskGetTickCount
+
+* uxStreamBufferGet
+* vReleaseNetworkBufferAndDescriptor
+* vSocketWakeUpUser

kernel/FreeRTOS-Plus/Source/FreeRTOS-Plus-TCP/test/cbmc/proofs/TCP/prvTCPPrepareSend/TCPPrepareSend_harness.c

@@ -0,0 +1,88 @@
+/*
+ * FreeRTOS memory safety proofs with CBMC.
+ * Copyright (C) 2022 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
+ */
+
+/* FreeRTOS includes. */
+#include "FreeRTOS.h"
+#include "queue.h"
+
+/* FreeRTOS+TCP includes. */
+#include "FreeRTOS_IP.h"
+#include "FreeRTOS_IP_Private.h"
+#include "FreeRTOS_TCP_IP.h"
+#include "FreeRTOS_Stream_Buffer.h"
+
+#include "../../utility/memory_assignments.c"
+
+/* This proof assumes that pxGetNetworkBufferWithDescriptor is implemented correctly. */
+int32_t publicTCPPrepareSend( FreeRTOS_Socket_t * pxSocket,
+                              NetworkBufferDescriptor_t ** ppxNetworkBuffer,
+                              UBaseType_t uxOptionsLength );
+
+/* Abstraction of pxGetNetworkBufferWithDescriptor. It creates a buffer. */
+NetworkBufferDescriptor_t * pxGetNetworkBufferWithDescriptor( size_t xRequestedSizeBytes,
+                                                              TickType_t xBlockTimeTicks )
+{
+    NetworkBufferDescriptor_t * pxBuffer = ensure_FreeRTOS_NetworkBuffer_is_allocated();
+    size_t bufferSize = sizeof( NetworkBufferDescriptor_t );
+
+    if( ensure_memory_is_valid( pxBuffer, bufferSize ) )
+    {
+        /* The code does not expect pucEthernetBuffer to be equal to NULL if
+         * pxBuffer is not NULL. */
+        pxBuffer->pucEthernetBuffer = malloc( xRequestedSizeBytes );
+        __CPROVER_assume( pxBuffer->pucEthernetBuffer != NULL );
+        pxBuffer->xDataLength = xRequestedSizeBytes;
+    }
+
+    return pxBuffer;
+}
+
+void harness()
+{
+    FreeRTOS_Socket_t * pxSocket = ensure_FreeRTOS_Socket_t_is_allocated();
+    NetworkBufferDescriptor_t * pxNetworkBuffer = ensure_FreeRTOS_NetworkBuffer_is_allocated();
+    size_t socketSize = sizeof( FreeRTOS_Socket_t );
+    size_t bufferSize = sizeof( TCPPacket_t );
+
+    if( ensure_memory_is_valid( pxNetworkBuffer, sizeof( *pxNetworkBuffer ) ) )
+    {
+        pxNetworkBuffer->xDataLength = bufferSize;
+
+        /* The code does not expect pucEthernetBuffer to be equal to NULL if
+         * pxNetworkBuffer is not NULL. */
+        pxNetworkBuffer->pucEthernetBuffer = malloc( bufferSize );
+        __CPROVER_assume( pxNetworkBuffer->pucEthernetBuffer != NULL );
+    }
+
+    UBaseType_t uxOptionsLength;
+
+    if( pxSocket )
+    {
+        publicTCPPrepareSend( pxSocket, &pxNetworkBuffer, uxOptionsLength );
+    }
+}

kernel/FreeRTOS-Plus/Source/FreeRTOS-Plus-TCP/test/cbmc/proofs/TCP/prvTCPReturnPacket/Makefile.json

@@ -0,0 +1,53 @@
+#
+# FreeRTOS memory safety proofs with CBMC.
+# Copyright (C) 2022 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
+#
+
+{
+  "ENTRY": "TCPReturnPacket",
+  "RX_MESSAGES":1,
+  "CBMCFLAGS":
+  [
+    "--unwind 1",
+    "--nondet-static"
+  ],
+  "OBJS":
+  [
+    "$(ENTRY)_harness.goto",
+    "$(FREERTOS_PLUS_TCP)/source/FreeRTOS_Stream_Buffer.goto",
+    "$(FREERTOS_PLUS_TCP)/source/FreeRTOS_IP.goto",
+    "$(FREERTOS_PLUS_TCP)/source/FreeRTOS_TCP_IP.goto"
+  ],
+  "DEF":
+  [
+    "ipconfigUSE_LINKED_RX_MESSAGES={RX_MESSAGES}",
+    "FREERTOS_TCP_ENABLE_VERIFICATION"
+  ],
+  "INC":
+  [
+    "$(FREERTOS_PLUS_TCP)/test/cbmc/include"
+  ]
+}

kernel/FreeRTOS-Plus/Source/FreeRTOS-Plus-TCP/test/cbmc/proofs/TCP/prvTCPReturnPacket/README.md

@@ -0,0 +1,10 @@
+This is the memory safety proof for prvTCPReturnPacket.
+
+This proof is a work-in-progress.  Proof assumptions are described in
+the harness.  The proof also assumes the following functions are
+memory safe and have no side effects relevant to the memory safety of
+this function:
+
+* usGenerateChecksum
+* usGenerateProtocolChecksum
+* xNetworkInterfaceOutput

kernel/FreeRTOS-Plus/Source/FreeRTOS-Plus-TCP/test/cbmc/proofs/TCP/prvTCPReturnPacket/TCPReturnPacket_harness.c

@@ -0,0 +1,127 @@
+/*
+ * FreeRTOS memory safety proofs with CBMC.
+ * Copyright (C) 2022 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
+ */
+
+/* FreeRTOS includes. */
+#include "FreeRTOS.h"
+#include "queue.h"
+
+/* FreeRTOS+TCP includes. */
+#include "FreeRTOS_IP.h"
+#include "FreeRTOS_IP_Private.h"
+#include "FreeRTOS_TCP_IP.h"
+
+#include "../../utility/memory_assignments.c"
+
+#include "cbmc.h"
+
+/* This proof assumes that pxDuplicateNetworkBufferWithDescriptor is implemented correctly. */
+void publicTCPReturnPacket( FreeRTOS_Socket_t * pxSocket,
+                            NetworkBufferDescriptor_t * pxNetworkBuffer,
+                            uint32_t ulLen,
+                            BaseType_t xReleaseAfterSend );
+
+/* Abstraction of pxDuplicateNetworkBufferWithDescriptor*/
+NetworkBufferDescriptor_t * pxDuplicateNetworkBufferWithDescriptor( const NetworkBufferDescriptor_t * const pxNetworkBuffer,
+                                                                    size_t xNewLength )
+{
+    NetworkBufferDescriptor_t * pxNetworkBuffer = ensure_FreeRTOS_NetworkBuffer_is_allocated();
+
+    if( ensure_memory_is_valid( pxNetworkBuffer, sizeof( *pxNetworkBuffer ) ) )
+    {
+        pxNetworkBuffer->pucEthernetBuffer = safeMalloc( sizeof( TCPPacket_t ) );
+        __CPROVER_assume( pxNetworkBuffer->pucEthernetBuffer );
+    }
+
+    return pxNetworkBuffer;
+}
+
+BaseType_t xNetworkInterfaceOutput( NetworkBufferDescriptor_t * pxDescriptor,
+                                    BaseType_t xReleaseAfterSend )
+{
+    BaseType_t xReturn;
+
+    __CPROVER_assert( pxDescriptor != NULL, "The descriptor cannot be NULL" );
+    __CPROVER_assert( pxDescriptor->pucEthernetBuffer != NULL, "The ethernet buffer cannot be NULL" );
+
+    return xReturn;
+}
+
+uint16_t usGenerateProtocolChecksum( const uint8_t * const pucEthernetBuffer,
+                                     size_t uxBufferLength,
+                                     BaseType_t xOutgoingPacket )
+{
+    __CPROVER_assert( pucEthernetBuffer != NULL, "The ethernet buffer cannot be NULL" );
+    __CPROVER_assert( __CPROVER_r_ok( pucEthernetBuffer, uxBufferLength ), "pucEthernetBuffer should be readable." );
+
+    uint16_t usReturn;
+    return usReturn;
+}
+
+uint16_t usGenerateChecksum( uint16_t usSum,
+                             const uint8_t * pucNextData,
+                             size_t uxByteCount )
+{
+    __CPROVER_assert( pucNextData != NULL, "The next data pointer cannot be NULL" );
+    __CPROVER_assert( __CPROVER_r_ok( pucNextData, uxByteCount ), "The pucNextData should be readable." );
+
+    uint16_t usReturn;
+    return usReturn;
+}
+
+void harness()
+{
+    FreeRTOS_Socket_t * pxSocket = ensure_FreeRTOS_Socket_t_is_allocated();
+    NetworkBufferDescriptor_t * pxNetworkBuffer = ensure_FreeRTOS_NetworkBuffer_is_allocated();
+
+    /* The code does not expect both of these to be equal to NULL at the same time. */
+    __CPROVER_assume( pxSocket != NULL || pxNetworkBuffer != NULL );
+
+    uint32_t ulLen;
+
+    /* If network buffer is properly created. */
+    if( ensure_memory_is_valid( pxNetworkBuffer, sizeof( *pxNetworkBuffer ) ) )
+    {
+        /* Assume that the length is proper. */
+        __CPROVER_assume( ( ulLen >= sizeof( TCPPacket_t ) ) && ( ulLen < ipconfigNETWORK_MTU ) );
+        pxNetworkBuffer->pucEthernetBuffer = safeMalloc( ulLen + ipSIZE_OF_ETH_HEADER );
+        __CPROVER_assume( pxNetworkBuffer->pucEthernetBuffer );
+    }
+    /* If not. */
+    else
+    {
+        /* Assume that the length is proper. The length should be between this range. It
+         * is made so by the functions up the call tree. Essentially, this is equal to a
+         * TCP packet header with and without TCP options. */
+        __CPROVER_assume( ( ulLen >= ipSIZE_OF_IPv4_HEADER + ipSIZE_OF_TCP_HEADER ) &&
+                          ( ulLen <= ipSIZE_OF_IPv4_HEADER + ipSIZE_OF_TCP_HEADER + 40 /* Maximum option bytes. */ ) );
+    }
+
+    BaseType_t xReleaseAfterSend;
+
+    publicTCPReturnPacket( pxSocket, pxNetworkBuffer, ulLen, xReleaseAfterSend );
+}