Sync FreeRTOS-Plus/Source/FreeRTOS-Plus-TCP with the version in GitHub at (23665258cabe49d5d68ba23968b6845a7c80eb34).

Notes: 
- header has version 2.2.0. 
- This sync did not bring in ./test directory, though we should. 
- New NetworkInterfaces are introduced by this merge.
- Keil compiler support. 
- FreeRTOS_IP.h new API xApplicationGetRandomNumber().
- FreeRTOS_IP_Private.h new eIPEvent_t eNetworkTxEvent. 
- FreeRTOS_Stream_Buffer.h removing static xStreamBufferIsEmpty() and xStreamBufferIsFull().
- FreeRTOSConfigDefaults.h provides default ipconfigDNS_RECEIVE_BLOCK_TIME_TICKS. 
- other type changes.

Author: yuhui-zheng

FreeRTOS-Plus/Source/FreeRTOS-Plus-TCP/FreeRTOS_ARP.c

@@ -1,5 +1,5 @@
 /*
- * FreeRTOS+TCP V2.0.11
+ * FreeRTOS+TCP V2.2.0
  * Copyright (C) 2017 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy of
@@ -580,15 +580,37 @@ NetworkBufferDescriptor_t *pxNetworkBuffer;
 			}
 		}
 		#endif
+		if( xIsCallingFromIPTask() != 0 )
+		{
+			/* Only the IP-task is allowed to call this function directly. */
+			xNetworkInterfaceOutput( pxNetworkBuffer, pdTRUE );
+		}
+		else
+		{
+		IPStackEvent_t xSendEvent;
 
-		xNetworkInterfaceOutput( pxNetworkBuffer, pdTRUE );
+			/* Send a message to the IP-task to send this ARP packet. */
+			xSendEvent.eEventType = eNetworkTxEvent;
+			xSendEvent.pvData = ( void * ) pxNetworkBuffer;
+			if( xSendEventStructToIPTask( &xSendEvent, ( TickType_t ) portMAX_DELAY ) == pdFAIL )
+			{
+				/* Failed to send the message, so release the network buffer. */
+				vReleaseNetworkBufferAndDescriptor( pxNetworkBuffer );
+			}
+		}
 	}
 }
 
 void vARPGenerateRequestPacket( NetworkBufferDescriptor_t * const pxNetworkBuffer )
 {
 ARPPacket_t *pxARPPacket;
 
+	/* Buffer allocation ensures that buffers always have space
+	for an ARP packet. See buffer allocation implementations 1
+	and 2 under portable/BufferManagement. */
+	configASSERT( pxNetworkBuffer );
+	configASSERT( pxNetworkBuffer->xDataLength >= sizeof(ARPPacket_t) );
+
 	pxARPPacket = ( ARPPacket_t * ) pxNetworkBuffer->pucEthernetBuffer;
 
 	/* memcpy the const part of the header information into the correct

FreeRTOS-Plus/Source/FreeRTOS-Plus-TCP/FreeRTOS_DHCP.c

@@ -1,5 +1,5 @@
 /*
- * FreeRTOS+TCP V2.0.11
+ * FreeRTOS+TCP V2.2.0
  * Copyright (C) 2017 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a copy of
@@ -84,9 +84,9 @@
 
 /* Offsets into the transmitted DHCP options fields at which various parameters
 are located. */
-#define dhcpCLIENT_IDENTIFIER_OFFSET			( 5 )
-#define dhcpREQUESTED_IP_ADDRESS_OFFSET			( 13 )
-#define dhcpDHCP_SERVER_IP_ADDRESS_OFFSET		( 19 )
+#define dhcpCLIENT_IDENTIFIER_OFFSET			( 6 )
+#define dhcpREQUESTED_IP_ADDRESS_OFFSET			( 14 )
+#define dhcpDHCP_SERVER_IP_ADDRESS_OFFSET		( 20 )
 
 /* Values used in the DHCP packets. */
 #define dhcpREQUEST_OPCODE						( 1 )
@@ -354,9 +354,7 @@ BaseType_t xGivingUp = pdFALSE;
 
 				if( xDHCPData.xDHCPTxPeriod <= ipconfigMAXIMUM_DISCOVER_TX_PERIOD )
 				{
-					xDHCPData.ulTransactionId = ipconfigRAND32( );
-
-					if( 0 != xDHCPData.ulTransactionId )
+					if( xApplicationGetRandomNumber( &( xDHCPData.ulTransactionId ) ) != pdFALSE )
 					{
 						xDHCPData.xDHCPTxTime = xTaskGetTickCount( );
 						xDHCPData.xUseBroadcast = !xDHCPData.xUseBroadcast;
@@ -589,10 +587,9 @@ static void prvInitialiseDHCP( void )
 	/* Initialise the parameters that will be set by the DHCP process. Per
 	https://www.ietf.org/rfc/rfc2131.txt, Transaction ID should be a random
 	value chosen by the client. */
-	xDHCPData.ulTransactionId = ipconfigRAND32();
 
 	/* Check for random number generator API failure. */
-	if( 0 != xDHCPData.ulTransactionId )
+	if( xApplicationGetRandomNumber( &( xDHCPData.ulTransactionId ) ) != pdFALSE )
 	{
 		xDHCPData.xUseBroadcast = 0;
 		xDHCPData.ulOfferedIPAddress = 0UL;
@@ -604,6 +601,10 @@ static void prvInitialiseDHCP( void )
 		FreeRTOS_debug_printf( ( "prvInitialiseDHCP: start after %lu ticks\n", dhcpINITIAL_TIMER_PERIOD ) );
 		vIPReloadDHCPTimer( dhcpINITIAL_TIMER_PERIOD );
 	}
+	else
+	{
+		/* There was a problem with the randomiser. */
+	}
 }
 /*-----------------------------------------------------------*/
 
@@ -642,8 +643,8 @@ const uint32_t ulMandatoryOptions = 2ul; /* DHCP server address, and the correct
 				/* Walk through the options until the dhcpOPTION_END_BYTE byte
 				is found, taking care not to walk off the end of the options. */
 				pucByte = &( pxDHCPMessage->ucFirstOptionByte );
-				/* Maintain a pointer to the last valid byte (i.e. not the first
-				invalid byte). */
+                /* Maintain a pointer to the last valid byte (i.e. not the first
+                invalid byte). */
 				pucLastByte = pucUDPPayload + lBytes - 1;
 
 				while( pucByte <= pucLastByte )
@@ -665,7 +666,7 @@ const uint32_t ulMandatoryOptions = 2ul; /* DHCP server address, and the correct
 					/* Stop if the response is malformed. */
 					if( pucByte < pucLastByte )
 					{
-						/* There are at least two bytes left. */
+                        /* There are at least two bytes left. */
 						ucLength = pucByte[ 1 ];
 						pucByte += 2;
 
@@ -904,7 +905,7 @@ static const uint8_t ucDHCPRequestOptions[] =
 	dhcpCLIENT_IDENTIFIER_OFFSET, dhcpREQUESTED_IP_ADDRESS_OFFSET and
 	dhcpDHCP_SERVER_IP_ADDRESS_OFFSET. */
 	dhcpMESSAGE_TYPE_OPTION_CODE, 1, dhcpMESSAGE_TYPE_REQUEST,		/* Message type option. */
-	dhcpCLIENT_IDENTIFIER_OPTION_CODE, 6, 0, 0, 0, 0, 0, 0,			/* Client identifier. */
+	dhcpCLIENT_IDENTIFIER_OPTION_CODE, 7, 1, 0, 0, 0, 0, 0, 0,			/* Client identifier. */
 	dhcpREQUEST_IP_ADDRESS_OPTION_CODE, 4, 0, 0, 0, 0,				/* The IP address being requested. */
 	dhcpSERVER_IP_ADDRESS_OPTION_CODE, 4, 0, 0, 0, 0,				/* The IP address of the DHCP server. */
 	dhcpOPTION_END_BYTE
@@ -942,7 +943,7 @@ static const uint8_t ucDHCPDiscoverOptions[] =
 {
 	/* Do not change the ordering without also changing dhcpCLIENT_IDENTIFIER_OFFSET. */
 	dhcpMESSAGE_TYPE_OPTION_CODE, 1, dhcpMESSAGE_TYPE_DISCOVER,					/* Message type option. */
-	dhcpCLIENT_IDENTIFIER_OPTION_CODE, 6, 0, 0, 0, 0, 0, 0,						/* Client identifier. */
+	dhcpCLIENT_IDENTIFIER_OPTION_CODE, 7, 1, 0, 0, 0, 0, 0, 0,						/* Client identifier. */
 	dhcpPARAMETER_REQUEST_OPTION_CODE, 3, dhcpSUBNET_MASK_OPTION_CODE, dhcpGATEWAY_OPTION_CODE, dhcpDNS_SERVER_OPTIONS_CODE,	/* Parameter request option. */
 	dhcpOPTION_END_BYTE
 };
@@ -968,13 +969,16 @@ size_t xOptionsLength = sizeof( ucDHCPDiscoverOptions );
 	static void prvPrepareLinkLayerIPLookUp( void )
 	{
 	uint8_t ucLinkLayerIPAddress[ 2 ];
+	uint32_t ulNumbers[ 2 ];
 
 		/* After DHCP has failed to answer, prepare everything to start
 		trying-out LinkLayer IP-addresses, using the random method. */
 		xDHCPData.xDHCPTxTime = xTaskGetTickCount();
 
-		ucLinkLayerIPAddress[ 0 ] = ( uint8_t )1 + ( uint8_t )( ipconfigRAND32() % 0xFDu );		/* get value 1..254 for IP-address 3rd byte of IP address to try. */
-		ucLinkLayerIPAddress[ 1 ] = ( uint8_t )1 + ( uint8_t )( ipconfigRAND32() % 0xFDu );		/* get value 1..254 for IP-address 4th byte of IP address to try. */
+		xApplicationGetRandomNumber( &( ulNumbers[ 0 ] ) );
+		xApplicationGetRandomNumber( &( ulNumbers[ 1 ] ) );
+		ucLinkLayerIPAddress[ 0 ] = ( uint8_t )1 + ( uint8_t )( ulNumbers[ 0 ] % 0xFDu );		/* get value 1..254 for IP-address 3rd byte of IP address to try. */
+		ucLinkLayerIPAddress[ 1 ] = ( uint8_t )1 + ( uint8_t )( ulNumbers[ 1 ] % 0xFDu );		/* get value 1..254 for IP-address 4th byte of IP address to try. */
 
 		xNetworkAddressing.ulGatewayAddress = FreeRTOS_htonl( 0xA9FE0203 );
 
@@ -995,9 +999,15 @@ size_t xOptionsLength = sizeof( ucDHCPDiscoverOptions );
 		xNetworkAddressing.ulBroadcastAddress = ( xDHCPData.ulOfferedIPAddress & xNetworkAddressing.ulNetMask ) |  ~xNetworkAddressing.ulNetMask;
 
 		/* Close socket to ensure packets don't queue on it. not needed anymore as DHCP failed. but still need timer for ARP testing. */
-		vSocketClose( xDHCPData.xDHCPSocket );
-		xDHCPData.xDHCPSocket = NULL;
-		xDHCPData.xDHCPTxPeriod = pdMS_TO_TICKS( 3000ul + ( ipconfigRAND32() & 0x3fful ) ); /*  do ARP test every (3 + 0-1024mS) seconds. */
+		if( xDHCPData.xDHCPSocket != NULL )
+		{
+			/* Close socket to ensure packets don't queue on it. */
+			vSocketClose( xDHCPData.xDHCPSocket );
+		    xDHCPData.xDHCPSocket = NULL;
+		}
+
+		xApplicationGetRandomNumber( &( ulNumbers[ 0 ] ) );
+		xDHCPData.xDHCPTxPeriod = pdMS_TO_TICKS( 3000ul + ( ulNumbers[ 0 ] & 0x3ffuL ) ); /*  do ARP test every (3 + 0-1024mS) seconds. */
 
 		xARPHadIPClash = pdFALSE;	   /* reset flag that shows if have ARP clash. */
 		vARPSendGratuitous();