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