Merge commit '60b30c036397cb5627fa374bb930794b225daa29' as 'lib/lufa'

1 files changed, 632 insertions, 0 deletions

diff --git a/lib/lufa/Demos/Device/ClassDriver/RNDISEthernet/Lib/TCP.c b/lib/lufa/Demos/Device/ClassDriver/RNDISEthernet/Lib/TCP.c
new file mode 100644
index 0000000000..dcc527aa97
--- /dev/null
+++ b/lib/lufa/Demos/Device/ClassDriver/RNDISEthernet/Lib/TCP.c
@@ -0,0 +1,632 @@
+/*
+             LUFA Library
+     Copyright (C) Dean Camera, 2017.
+
+  dean [at] fourwalledcubicle [dot] com
+           www.lufa-lib.org
+*/
+
+/*
+  Copyright 2017  Dean Camera (dean [at] fourwalledcubicle [dot] com)
+
+  Permission to use, copy, modify, distribute, and sell this
+  software and its documentation for any purpose is hereby granted
+  without fee, provided that the above copyright notice appear in
+  all copies and that both that the copyright notice and this
+  permission notice and warranty disclaimer appear in supporting
+  documentation, and that the name of the author not be used in
+  advertising or publicity pertaining to distribution of the
+  software without specific, written prior permission.
+
+  The author disclaims all warranties with regard to this
+  software, including all implied warranties of merchantability
+  and fitness.  In no event shall the author be liable for any
+  special, indirect or consequential damages or any damages
+  whatsoever resulting from loss of use, data or profits, whether
+  in an action of contract, negligence or other tortious action,
+  arising out of or in connection with the use or performance of
+  this software.
+*/
+
+/** \file
+ *
+ *  Transmission Control Protocol (TCP) packet handling routines. This protocol handles the reliable in-order transmission
+ *  and reception of packets to and from devices on a network, to "ports" on the device. It is used in situations where data
+ *  delivery must be reliable and correct, e.g. HTTP, TELNET and most other non-streaming protocols.
+ */
+
+#define  INCLUDE_FROM_TCP_C
+#include "TCP.h"
+
+/** Port state table array. This contains the current status of TCP ports in the device. To save on space, only open ports are
+ *  stored - closed ports may be overwritten at any time, and the system will assume any ports not present in the array are closed. This
+ *  allows for MAX_OPEN_TCP_PORTS to be less than the number of ports used by the application if desired.
+ */
+TCP_PortState_t        PortStateTable[MAX_OPEN_TCP_PORTS];
+
+/** Connection state table array. This contains the current status of TCP connections in the device. To save on space, only active
+ *  (non-closed) connections are stored - closed connections may be overwritten at any time, and the system will assume any connections
+ *  not present in the array are closed.
+ */
+TCP_ConnectionState_t  ConnectionStateTable[MAX_TCP_CONNECTIONS];
+
+
+/** Task to handle the calling of each registered application's callback function, to process and generate TCP packets at the application
+ *  level. If an application produces a response, this task constructs the appropriate Ethernet frame and places it into the Ethernet OUT
+ *  buffer for later transmission.
+ */
+void TCP_TCPTask(USB_ClassInfo_RNDIS_Device_t* const RNDISInterfaceInfo,
+		         Ethernet_Frame_Info_t* const FrameOUT)
+{
+	/* Run each application in sequence, to process incoming and generate outgoing packets */
+	for (uint8_t CSTableEntry = 0; CSTableEntry < MAX_TCP_CONNECTIONS; CSTableEntry++)
+	{
+		/* Find the corresponding port entry in the port table */
+		for (uint8_t PTableEntry = 0; PTableEntry < MAX_OPEN_TCP_PORTS; PTableEntry++)
+		{
+			/* Run the application handler for the port */
+			if ((PortStateTable[PTableEntry].Port  == ConnectionStateTable[CSTableEntry].Port) &&
+			    (PortStateTable[PTableEntry].State == TCP_Port_Open))
+			{
+				PortStateTable[PTableEntry].ApplicationHandler(&ConnectionStateTable[CSTableEntry],
+				                                               &ConnectionStateTable[CSTableEntry].Info.Buffer);
+			}
+		}
+	}
+
+	/* Bail out early if there is already a frame waiting to be sent in the Ethernet OUT buffer */
+	if (FrameOUT->FrameLength)
+	  return;
+
+	/* Send response packets from each application as the TCP packet buffers are filled by the applications */
+	for (uint8_t CSTableEntry = 0; CSTableEntry < MAX_TCP_CONNECTIONS; CSTableEntry++)
+	{
+		/* For each completely received packet, pass it along to the listening application */
+		if ((ConnectionStateTable[CSTableEntry].Info.Buffer.Direction == TCP_PACKETDIR_OUT) &&
+		    (ConnectionStateTable[CSTableEntry].Info.Buffer.Ready))
+		{
+			Ethernet_Frame_Header_t* FrameOUTHeader = (Ethernet_Frame_Header_t*)&FrameOUT->FrameData;
+			IP_Header_t*             IPHeaderOUT    = (IP_Header_t*)&FrameOUT->FrameData[sizeof(Ethernet_Frame_Header_t)];
+			TCP_Header_t*            TCPHeaderOUT   = (TCP_Header_t*)&FrameOUT->FrameData[sizeof(Ethernet_Frame_Header_t) +
+			                                                                              sizeof(IP_Header_t)];
+			void*                    TCPDataOUT     = &FrameOUT->FrameData[sizeof(Ethernet_Frame_Header_t) +
+			                                                               sizeof(IP_Header_t) +
+			                                                               sizeof(TCP_Header_t)];
+
+			uint16_t PacketSize = ConnectionStateTable[CSTableEntry].Info.Buffer.Length;
+
+			/* Fill out the TCP data */
+			TCPHeaderOUT->SourcePort           = ConnectionStateTable[CSTableEntry].Port;
+			TCPHeaderOUT->DestinationPort      = ConnectionStateTable[CSTableEntry].RemotePort;
+			TCPHeaderOUT->SequenceNumber       = SwapEndian_32(ConnectionStateTable[CSTableEntry].Info.SequenceNumberOut);
+			TCPHeaderOUT->AcknowledgmentNumber = SwapEndian_32(ConnectionStateTable[CSTableEntry].Info.SequenceNumberIn);
+			TCPHeaderOUT->DataOffset           = (sizeof(TCP_Header_t) / sizeof(uint32_t));
+			TCPHeaderOUT->WindowSize           = SwapEndian_16(TCP_WINDOW_SIZE);
+
+			TCPHeaderOUT->Flags                = TCP_FLAG_ACK;
+			TCPHeaderOUT->UrgentPointer        = 0;
+			TCPHeaderOUT->Checksum             = 0;
+			TCPHeaderOUT->Reserved             = 0;
+
+			memcpy(TCPDataOUT, ConnectionStateTable[CSTableEntry].Info.Buffer.Data, PacketSize);
+
+			ConnectionStateTable[CSTableEntry].Info.SequenceNumberOut += PacketSize;
+
+			TCPHeaderOUT->Checksum             = TCP_Checksum16(TCPHeaderOUT, &ServerIPAddress,
+			                                                    &ConnectionStateTable[CSTableEntry].RemoteAddress,
+			                                                    (sizeof(TCP_Header_t) + PacketSize));
+
+			PacketSize += sizeof(TCP_Header_t);
+
+			/* Fill out the response IP header */
+			IPHeaderOUT->TotalLength        = SwapEndian_16(sizeof(IP_Header_t) + PacketSize);
+			IPHeaderOUT->TypeOfService      = 0;
+			IPHeaderOUT->HeaderLength       = (sizeof(IP_Header_t) / sizeof(uint32_t));
+			IPHeaderOUT->Version            = 4;
+			IPHeaderOUT->Flags              = 0;
+			IPHeaderOUT->FragmentOffset     = 0;
+			IPHeaderOUT->Identification     = 0;
+			IPHeaderOUT->HeaderChecksum     = 0;
+			IPHeaderOUT->Protocol           = PROTOCOL_TCP;
+			IPHeaderOUT->TTL                = DEFAULT_TTL;
+			IPHeaderOUT->SourceAddress      = ServerIPAddress;
+			IPHeaderOUT->DestinationAddress = ConnectionStateTable[CSTableEntry].RemoteAddress;
+
+			IPHeaderOUT->HeaderChecksum     = Ethernet_Checksum16(IPHeaderOUT, sizeof(IP_Header_t));
+
+			PacketSize += sizeof(IP_Header_t);
+
+			/* Fill out the response Ethernet frame header */
+			FrameOUTHeader->Source          = ServerMACAddress;
+			FrameOUTHeader->Destination     = (MAC_Address_t){{0x02, 0x00, 0x02, 0x00, 0x02, 0x00}};
+			FrameOUTHeader->EtherType       = SwapEndian_16(ETHERTYPE_IPV4);
+
+			PacketSize += sizeof(Ethernet_Frame_Header_t);
+
+			/* Set the response length in the buffer and indicate that a response is ready to be sent */
+			FrameOUT->FrameLength           = PacketSize;
+
+			ConnectionStateTable[CSTableEntry].Info.Buffer.Ready = false;
+
+			break;
+		}
+	}
+}
+
+/** Initializes the TCP protocol handler, clearing the port and connection state tables. This must be called before TCP packets are
+ *  processed.
+ */
+void TCP_Init(void)
+{
+	/* Initialize the port state table with all CLOSED entries */
+	for (uint8_t PTableEntry = 0; PTableEntry < MAX_OPEN_TCP_PORTS; PTableEntry++)
+	  PortStateTable[PTableEntry].State = TCP_Port_Closed;
+
+	/* Initialize the connection table with all CLOSED entries */
+	for (uint8_t CSTableEntry = 0; CSTableEntry < MAX_TCP_CONNECTIONS; CSTableEntry++)
+	  ConnectionStateTable[CSTableEntry].State = TCP_Connection_Closed;
+}
+
+/** Sets the state and callback handler of the given port, specified in big endian to the given state.
+ *
+ *  \param[in] Port     Port whose state and callback function to set, specified in big endian
+ *  \param[in] State    New state of the port, a value from the \ref TCP_PortStates_t enum
+ *  \param[in] Handler  Application callback handler for the port
+ *
+ *  \return Boolean \c true if the port state was set, \c false otherwise (no more space in the port state table)
+ */
+bool TCP_SetPortState(const uint16_t Port,
+                      const uint8_t State,
+                      void (*Handler)(TCP_ConnectionState_t*, TCP_ConnectionBuffer_t*))
+{
+	/* Note, Port number should be specified in BIG endian to simplify network code */
+
+	/* Check to see if the port entry is already in the port state table */
+	for (uint8_t PTableEntry = 0; PTableEntry < MAX_OPEN_TCP_PORTS; PTableEntry++)
+	{
+		/* Find existing entry for the port in the table, update it if found */
+		if (PortStateTable[PTableEntry].Port == Port)
+		{
+			PortStateTable[PTableEntry].State = State;
+			PortStateTable[PTableEntry].ApplicationHandler = Handler;
+			return true;
+		}
+	}
+
+	/* Check if trying to open the port -- if so we need to find an unused (closed) entry and replace it */
+	if (State == TCP_Port_Open)
+	{
+		for (uint8_t PTableEntry = 0; PTableEntry < MAX_OPEN_TCP_PORTS; PTableEntry++)
+		{
+			/* Find a closed port entry in the table, change it to the given port and state */
+			if (PortStateTable[PTableEntry].State == TCP_Port_Closed)
+			{
+				PortStateTable[PTableEntry].Port  = Port;
+				PortStateTable[PTableEntry].State = State;
+				PortStateTable[PTableEntry].ApplicationHandler = Handler;
+				return true;
+			}
+		}
+
+		/* Port not in table and no room to add it, return failure */
+		return false;
+	}
+	else
+	{
+		/* Port not in table but trying to close it, so operation successful */
+		return true;
+	}
+}
+
+/** Retrieves the current state of a given TCP port, specified in big endian.
+ *
+ *  \param[in] Port  TCP port whose state is to be retrieved, given in big-endian
+ *
+ *  \return A value from the \ref TCP_PortStates_t enum
+ */
+uint8_t TCP_GetPortState(const uint16_t Port)
+{
+	/* Note, Port number should be specified in BIG endian to simplify network code */
+
+	for (uint8_t PTableEntry = 0; PTableEntry < MAX_OPEN_TCP_PORTS; PTableEntry++)
+	{
+		/* Find existing entry for the port in the table, return the port status if found */
+		if (PortStateTable[PTableEntry].Port == Port)
+		  return PortStateTable[PTableEntry].State;
+	}
+
+	/* Port not in table, assume closed */
+	return TCP_Port_Closed;
+}
+
+/** Sets the connection state of the given port, remote address and remote port to the given TCP connection state. If the
+ *  connection exists in the connection state table it is updated, otherwise it is created if possible.
+ *
+ *  \param[in] Port           TCP port of the connection on the device, specified in big endian
+ *  \param[in] RemoteAddress  Remote protocol IP address of the connected device
+ *  \param[in] RemotePort     TCP port of the remote device in the connection, specified in big endian
+ *  \param[in] State          TCP connection state, a value from the \ref TCP_ConnectionStates_t enum
+ *
+ *  \return Boolean \c true if the connection was updated or created, \c false otherwise (no more space in the connection state table)
+ */
+bool TCP_SetConnectionState(const uint16_t Port,
+                            const IP_Address_t* RemoteAddress,
+                            const uint16_t RemotePort,
+                            const uint8_t State)
+{
+	/* Note, Port number should be specified in BIG endian to simplify network code */
+
+	for (uint8_t CSTableEntry = 0; CSTableEntry < MAX_TCP_CONNECTIONS; CSTableEntry++)
+	{
+		/* Find port entry in the table */
+		if ((ConnectionStateTable[CSTableEntry].Port == Port) &&
+		     IP_COMPARE(&ConnectionStateTable[CSTableEntry].RemoteAddress, RemoteAddress) &&
+			 ConnectionStateTable[CSTableEntry].RemotePort == RemotePort)
+		{
+			ConnectionStateTable[CSTableEntry].State = State;
+			return true;
+		}
+	}
+
+	for (uint8_t CSTableEntry = 0; CSTableEntry < MAX_TCP_CONNECTIONS; CSTableEntry++)
+	{
+		/* Find empty entry in the table */
+		if (ConnectionStateTable[CSTableEntry].State == TCP_Connection_Closed)
+		{
+			ConnectionStateTable[CSTableEntry].Port          = Port;
+			ConnectionStateTable[CSTableEntry].RemoteAddress = *RemoteAddress;
+			ConnectionStateTable[CSTableEntry].RemotePort    = RemotePort;
+			ConnectionStateTable[CSTableEntry].State         = State;
+			return true;
+		}
+	}
+
+	return false;
+}
+
+/** Retrieves the current state of a given TCP connection to a host.
+ *
+ *  \param[in] Port           TCP port on the device in the connection, specified in big endian
+ *  \param[in] RemoteAddress  Remote protocol IP address of the connected host
+ *  \param[in] RemotePort     Remote TCP port of the connected host, specified in big endian
+ *
+ *  \return A value from the \ref TCP_ConnectionStates_t enum
+ */
+uint8_t TCP_GetConnectionState(const uint16_t Port,
+                               const IP_Address_t* RemoteAddress,
+                               const uint16_t RemotePort)
+{
+	/* Note, Port number should be specified in BIG endian to simplify network code */
+
+	for (uint8_t CSTableEntry = 0; CSTableEntry < MAX_TCP_CONNECTIONS; CSTableEntry++)
+	{
+		/* Find port entry in the table */
+		if ((ConnectionStateTable[CSTableEntry].Port == Port) &&
+		     IP_COMPARE(&ConnectionStateTable[CSTableEntry].RemoteAddress, RemoteAddress) &&
+			 ConnectionStateTable[CSTableEntry].RemotePort == RemotePort)
+
+		{
+			return ConnectionStateTable[CSTableEntry].State;
+		}
+	}
+
+	return TCP_Connection_Closed;
+}
+
+/** Retrieves the connection info structure of a given connection to a host.
+ *
+ *  \param[in] Port           TCP port on the device in the connection, specified in big endian
+ *  \param[in] RemoteAddress  Remote protocol IP address of the connected host
+ *  \param[in] RemotePort     Remote TCP port of the connected host, specified in big endian
+ *
+ *  \return ConnectionInfo structure of the connection if found, NULL otherwise
+ */
+TCP_ConnectionInfo_t* TCP_GetConnectionInfo(const uint16_t Port,
+                                            const IP_Address_t* RemoteAddress,
+                                            const uint16_t RemotePort)
+{
+	/* Note, Port number should be specified in BIG endian to simplify network code */
+
+	for (uint8_t CSTableEntry = 0; CSTableEntry < MAX_TCP_CONNECTIONS; CSTableEntry++)
+	{
+		/* Find port entry in the table */
+		if ((ConnectionStateTable[CSTableEntry].Port == Port) &&
+		     IP_COMPARE(&ConnectionStateTable[CSTableEntry].RemoteAddress, RemoteAddress) &&
+			 ConnectionStateTable[CSTableEntry].RemotePort == RemotePort)
+		{
+			return &ConnectionStateTable[CSTableEntry].Info;
+		}
+	}
+
+	return NULL;
+}
+
+/** Processes a TCP packet inside an Ethernet frame, and writes the appropriate response
+ *  to the output Ethernet frame if one is created by a application handler.
+ *
+ *  \param[in] IPHeaderInStart     Pointer to the start of the incoming packet's IP header
+ *  \param[in] TCPHeaderInStart    Pointer to the start of the incoming packet's TCP header
+ *  \param[out] TCPHeaderOutStart  Pointer to the start of the outgoing packet's TCP header
+ *
+ *  \return The number of bytes written to the out Ethernet frame if any, NO_RESPONSE if no
+ *           response was generated, NO_PROCESS if the packet processing was deferred until the
+ *           next Ethernet packet handler iteration
+ */
+int16_t TCP_ProcessTCPPacket(void* IPHeaderInStart,
+                             void* TCPHeaderInStart,
+                             void* TCPHeaderOutStart)
+{
+	IP_Header_t*  IPHeaderIN   = (IP_Header_t*)IPHeaderInStart;
+	TCP_Header_t* TCPHeaderIN  = (TCP_Header_t*)TCPHeaderInStart;
+	TCP_Header_t* TCPHeaderOUT = (TCP_Header_t*)TCPHeaderOutStart;
+
+	TCP_ConnectionInfo_t* ConnectionInfo;
+
+	DecodeTCPHeader(TCPHeaderInStart);
+
+	bool PacketResponse = false;
+
+	/* Check if the destination port is open and allows incoming connections */
+	if (TCP_GetPortState(TCPHeaderIN->DestinationPort) == TCP_Port_Open)
+	{
+		/* Detect SYN from host to start a connection */
+		if (TCPHeaderIN->Flags & TCP_FLAG_SYN)
+		  TCP_SetConnectionState(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress, TCPHeaderIN->SourcePort, TCP_Connection_Listen);
+
+		/* Detect RST from host to abort existing connection */
+		if (TCPHeaderIN->Flags & TCP_FLAG_RST)
+		{
+			if (TCP_SetConnectionState(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress,
+			                           TCPHeaderIN->SourcePort, TCP_Connection_Closed))
+			{
+				TCPHeaderOUT->Flags = (TCP_FLAG_RST | TCP_FLAG_ACK);
+				PacketResponse = true;
+			}
+		}
+		else
+		{
+			/* Process the incoming TCP packet based on the current connection state for the sender and port */
+			switch (TCP_GetConnectionState(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress, TCPHeaderIN->SourcePort))
+			{
+				case TCP_Connection_Listen:
+					if (TCPHeaderIN->Flags == TCP_FLAG_SYN)
+					{
+						/* SYN connection starts a connection with a peer */
+						if (TCP_SetConnectionState(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress,
+						                           TCPHeaderIN->SourcePort, TCP_Connection_SYNReceived))
+						{
+							TCPHeaderOUT->Flags = (TCP_FLAG_SYN | TCP_FLAG_ACK);
+
+							ConnectionInfo = TCP_GetConnectionInfo(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress, TCPHeaderIN->SourcePort);
+
+							ConnectionInfo->SequenceNumberIn  = (SwapEndian_32(TCPHeaderIN->SequenceNumber) + 1);
+							ConnectionInfo->SequenceNumberOut = 0;
+							ConnectionInfo->Buffer.InUse      = false;
+						}
+						else
+						{
+							TCPHeaderOUT->Flags = TCP_FLAG_RST;
+						}
+
+						PacketResponse      = true;
+					}
+
+					break;
+				case TCP_Connection_SYNReceived:
+					if (TCPHeaderIN->Flags == TCP_FLAG_ACK)
+					{
+						/* ACK during the connection process completes the connection to a peer */
+
+						TCP_SetConnectionState(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress,
+											   TCPHeaderIN->SourcePort, TCP_Connection_Established);
+
+						ConnectionInfo = TCP_GetConnectionInfo(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress,
+															   TCPHeaderIN->SourcePort);
+
+						ConnectionInfo->SequenceNumberOut++;
+					}
+
+					break;
+				case TCP_Connection_Established:
+					if (TCPHeaderIN->Flags == (TCP_FLAG_FIN | TCP_FLAG_ACK))
+					{
+						/* FIN ACK when connected to a peer starts the finalization process */
+
+						TCPHeaderOUT->Flags = (TCP_FLAG_FIN | TCP_FLAG_ACK);
+						PacketResponse      = true;
+
+						TCP_SetConnectionState(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress,
+											   TCPHeaderIN->SourcePort, TCP_Connection_CloseWait);
+
+						ConnectionInfo = TCP_GetConnectionInfo(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress,
+															   TCPHeaderIN->SourcePort);
+
+						ConnectionInfo->SequenceNumberIn++;
+						ConnectionInfo->SequenceNumberOut++;
+					}
+					else if ((TCPHeaderIN->Flags == TCP_FLAG_ACK) || (TCPHeaderIN->Flags == (TCP_FLAG_ACK | TCP_FLAG_PSH)))
+					{
+						ConnectionInfo = TCP_GetConnectionInfo(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress,
+															   TCPHeaderIN->SourcePort);
+
+						/* Check if the buffer is currently in use either by a buffered data to send, or receive */
+						if ((ConnectionInfo->Buffer.InUse == false) && (ConnectionInfo->Buffer.Ready == false))
+						{
+							ConnectionInfo->Buffer.Direction = TCP_PACKETDIR_IN;
+							ConnectionInfo->Buffer.InUse     = true;
+							ConnectionInfo->Buffer.Length    = 0;
+						}
+
+						/* Check if the buffer has been claimed by us to read in data from the peer */
+						if ((ConnectionInfo->Buffer.Direction == TCP_PACKETDIR_IN) &&
+							(ConnectionInfo->Buffer.Length != TCP_WINDOW_SIZE))
+						{
+							uint16_t IPOffset   = (IPHeaderIN->HeaderLength * sizeof(uint32_t));
+							uint16_t TCPOffset  = (TCPHeaderIN->DataOffset * sizeof(uint32_t));
+							uint16_t DataLength = (SwapEndian_16(IPHeaderIN->TotalLength) - IPOffset - TCPOffset);
+
+							/* Copy the packet data into the buffer */
+							memcpy(&ConnectionInfo->Buffer.Data[ConnectionInfo->Buffer.Length],
+								   &((uint8_t*)TCPHeaderInStart)[TCPOffset],
+								   DataLength);
+
+							ConnectionInfo->SequenceNumberIn += DataLength;
+							ConnectionInfo->Buffer.Length    += DataLength;
+
+							/* Check if the buffer is full or if the PSH flag is set, if so indicate buffer ready */
+							if ((!(TCP_WINDOW_SIZE - ConnectionInfo->Buffer.Length)) || (TCPHeaderIN->Flags & TCP_FLAG_PSH))
+							{
+								ConnectionInfo->Buffer.InUse = false;
+								ConnectionInfo->Buffer.Ready = true;
+
+								TCPHeaderOUT->Flags = TCP_FLAG_ACK;
+								PacketResponse      = true;
+							}
+						}
+						else
+						{
+							/* Buffer is currently in use by the application, defer processing of the incoming packet */
+							return NO_PROCESS;
+						}
+					}
+
+					break;
+				case TCP_Connection_Closing:
+						ConnectionInfo = TCP_GetConnectionInfo(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress,
+															   TCPHeaderIN->SourcePort);
+
+						TCPHeaderOUT->Flags = (TCP_FLAG_ACK | TCP_FLAG_FIN);
+						PacketResponse      = true;
+
+						ConnectionInfo->Buffer.InUse = false;
+
+						TCP_SetConnectionState(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress,
+											   TCPHeaderIN->SourcePort, TCP_Connection_FINWait1);
+
+					break;
+				case TCP_Connection_FINWait1:
+					if (TCPHeaderIN->Flags == (TCP_FLAG_FIN | TCP_FLAG_ACK))
+					{
+						ConnectionInfo = TCP_GetConnectionInfo(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress,
+															   TCPHeaderIN->SourcePort);
+
+						TCPHeaderOUT->Flags = TCP_FLAG_ACK;
+						PacketResponse      = true;
+
+						ConnectionInfo->SequenceNumberIn++;
+						ConnectionInfo->SequenceNumberOut++;
+
+						TCP_SetConnectionState(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress,
+											   TCPHeaderIN->SourcePort, TCP_Connection_Closed);
+					}
+					else if (TCPHeaderIN->Flags == TCP_FLAG_ACK)
+					{
+						TCP_SetConnectionState(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress,
+											   TCPHeaderIN->SourcePort, TCP_Connection_FINWait2);
+					}
+
+					break;
+				case TCP_Connection_FINWait2:
+					if (TCPHeaderIN->Flags == (TCP_FLAG_FIN | TCP_FLAG_ACK))
+					{
+						ConnectionInfo = TCP_GetConnectionInfo(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress,
+															   TCPHeaderIN->SourcePort);
+
+						TCPHeaderOUT->Flags = TCP_FLAG_ACK;
+						PacketResponse      = true;
+
+						ConnectionInfo->SequenceNumberIn++;
+						ConnectionInfo->SequenceNumberOut++;
+
+						TCP_SetConnectionState(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress,
+											   TCPHeaderIN->SourcePort, TCP_Connection_Closed);
+					}
+
+					break;
+				case TCP_Connection_CloseWait:
+					if (TCPHeaderIN->Flags == TCP_FLAG_ACK)
+					{
+						TCP_SetConnectionState(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress,
+											   TCPHeaderIN->SourcePort, TCP_Connection_Closed);
+					}
+
+					break;
+			}
+		}
+	}
+	else
+	{
+		/* Port is not open, indicate via a RST/ACK response to the sender */
+		TCPHeaderOUT->Flags = (TCP_FLAG_RST | TCP_FLAG_ACK);
+		PacketResponse      = true;
+	}
+
+	/* Check if we need to respond to the sent packet */
+	if (PacketResponse)
+	{
+		ConnectionInfo = TCP_GetConnectionInfo(TCPHeaderIN->DestinationPort, &IPHeaderIN->SourceAddress,
+		                                       TCPHeaderIN->SourcePort);
+
+		TCPHeaderOUT->SourcePort           = TCPHeaderIN->DestinationPort;
+		TCPHeaderOUT->DestinationPort      = TCPHeaderIN->SourcePort;
+		TCPHeaderOUT->SequenceNumber       = SwapEndian_32(ConnectionInfo->SequenceNumberOut);
+		TCPHeaderOUT->AcknowledgmentNumber = SwapEndian_32(ConnectionInfo->SequenceNumberIn);
+		TCPHeaderOUT->DataOffset           = (sizeof(TCP_Header_t) / sizeof(uint32_t));
+
+		if (!(ConnectionInfo->Buffer.InUse))
+		  TCPHeaderOUT->WindowSize         = SwapEndian_16(TCP_WINDOW_SIZE);
+		else
+		  TCPHeaderOUT->WindowSize         = SwapEndian_16(TCP_WINDOW_SIZE - ConnectionInfo->Buffer.Length);
+
+		TCPHeaderOUT->UrgentPointer        = 0;
+		TCPHeaderOUT->Checksum             = 0;
+		TCPHeaderOUT->Reserved             = 0;
+
+		TCPHeaderOUT->Checksum             = TCP_Checksum16(TCPHeaderOUT, &IPHeaderIN->DestinationAddress,
+		                                                    &IPHeaderIN->SourceAddress, sizeof(TCP_Header_t));
+
+		return sizeof(TCP_Header_t);
+	}
+
+	return NO_RESPONSE;
+}
+
+/** Calculates the appropriate TCP checksum, consisting of the addition of the one's compliment of each word,
+ *  complimented.
+ *
+ *  \param[in] TCPHeaderOutStart   Pointer to the start of the packet's outgoing TCP header
+ *  \param[in] SourceAddress       Source protocol IP address of the outgoing IP header
+ *  \param[in] DestinationAddress  Destination protocol IP address of the outgoing IP header
+ *  \param[in] TCPOutSize          Size in bytes of the TCP data header and payload
+ *
+ *  \return A 16-bit TCP checksum value
+ */
+static uint16_t TCP_Checksum16(void* TCPHeaderOutStart,
+                               const IP_Address_t* SourceAddress,
+                               const IP_Address_t* DestinationAddress,
+                               uint16_t TCPOutSize)
+{
+	uint32_t Checksum = 0;
+
+	/* TCP/IP checksums are the addition of the one's compliment of each word including the IP pseudo-header,
+	   complimented */
+
+	Checksum += ((uint16_t*)SourceAddress)[0];
+	Checksum += ((uint16_t*)SourceAddress)[1];
+	Checksum += ((uint16_t*)DestinationAddress)[0];
+	Checksum += ((uint16_t*)DestinationAddress)[1];
+	Checksum += SwapEndian_16(PROTOCOL_TCP);
+	Checksum += SwapEndian_16(TCPOutSize);
+
+	for (uint16_t CurrWord = 0; CurrWord < (TCPOutSize >> 1); CurrWord++)
+	  Checksum += ((uint16_t*)TCPHeaderOutStart)[CurrWord];
+
+	if (TCPOutSize & 0x01)
+	  Checksum += (((uint16_t*)TCPHeaderOutStart)[TCPOutSize >> 1] & 0x00FF);
+
+	while (Checksum & 0xFFFF0000)
+	  Checksum = ((Checksum & 0xFFFF) + (Checksum >> 16));
+
+	return ~Checksum;
+}
+