/****************************************************************** *****                                                        ***** *****  Name: tcpip.c                                         ***** *****  Ver.: 1.0                                             ***** *****  Date: 07/05/2001                                      ***** *****  Auth: Andreas Dannenberg                              ***** *****        HTWK Leipzig                                    ***** *****        university of applied sciences                  ***** *****        Germany                                         ***** *****        adannenb@et.htwk-leipzig.de                     ***** *****  Func: implements the TCP/IP-stack and provides a      ***** *****        simple API to the user                          ***** *****                                                        ***** ******************************************************************/#include "tcpip.h"// easyWEB-API function// initalizes the LAN-controller, reset flags, starts timer-ISRvoid TCPLowLevelInit(void){  BCSCTL1 &= ~DIVA0;                             // ACLK = XT1 / 4 = 2 MHz  BCSCTL1 |= DIVA1;  TACTL = ID1 | ID0 | TASSEL0 | TAIE;            // stop timer, use ACLK / 8 = 250 kHz, gen. int.  TACTL |= MC1;                                  // start timer in continuous up-mode  _EINT();                                       // enable interrupts    Init8900();  TransmitControl = 0;  TCPFlags = 0;  TCPStateMachine = CLOSED;  SocketStatus = 0;}// easyWEB-API function// does a passive open (listen on 'MyIP:TCPLocalPort' for an incoming// connection)void TCPPassiveOpen(void){  if (TCPStateMachine == CLOSED)  {    TCPFlags &= ~TCP_ACTIVE_OPEN;                // let's do a passive open!    TCPStateMachine = LISTENING;    SocketStatus = SOCK_ACTIVE;                  // reset, socket now active  }}// easyWEB-API function// does an active open (tries to establish a connection between// 'MyIP:TCPLocalPort' and 'RemoteIP:TCPRemotePort')void TCPActiveOpen(void){  if ((TCPStateMachine == CLOSED) || (TCPStateMachine == LISTENING))  {    TCPFlags |= TCP_ACTIVE_OPEN;                 // let's do an active open!    TCPFlags &= ~IP_ADDR_RESOLVED;               // we haven't opponents MAC yet      PrepareARP_REQUEST();                        // ask for MAC by sending a broadcast    LastFrameSent = ARP_REQUEST;    TCPStartRetryTimer();    SocketStatus = SOCK_ACTIVE;                  // reset, socket now active      }}// easyWEB-API function// closes an open connectionvoid TCPClose(void){  switch (TCPStateMachine)  {    case LISTENING :    case SYN_SENT :    {      TCPStateMachine = CLOSED;      TCPFlags = 0;      SocketStatus = 0;      break;    }    case SYN_RECD :    case ESTABLISHED :    {      TCPFlags |= TCP_CLOSE_REQUESTED;      break;    }  }}// easyWEB-API function// releases the receive-buffer and allows easyWEB to store new data// NOTE: rx-buffer MUST be released periodically, else the other TCP//       get no ACKs for the data it sentvoid TCPReleaseRxBuffer(void){  SocketStatus &= ~SOCK_DATA_AVAILABLE;}// easyWEB-API function// transmitts data stored in 'TCP_TX_BUF'// NOTE: * number of bytes to transmit must have been written to 'TCPTxDataCount'//       * data-count MUST NOT exceed 'MAX_TCP_TX_DATA_SIZE'void TCPTransmitTxBuffer(void){  if ((TCPStateMachine == ESTABLISHED) || (TCPStateMachine == CLOSE_WAIT))    if (SocketStatus & SOCK_TX_BUF_RELEASED)    {      SocketStatus &= ~SOCK_TX_BUF_RELEASED;               // occupy tx-buffer      TCPUNASeqNr += TCPTxDataCount;                       // advance UNA            TxFrame1Size = ETH_HEADER_SIZE + IP_HEADER_SIZE + TCP_HEADER_SIZE + TCPTxDataCount;      TransmitControl |= SEND_FRAME1;            LastFrameSent = TCP_DATA_FRAME;      TCPStartRetryTimer();    }}// easyWEB's 'main()'-function// must be called from user program periodically (the often - the better)// handles network, TCP/IP-stack and user eventsvoid DoNetworkStuff(void){  unsigned int ActRxEvent;                       // copy of cs8900's RxEvent-Register  Write8900(ADD_PORT, PP_RxEvent);               // point to RxEvent  ActRxEvent = Read8900(DATA_PORT);              // read, implied skip the last frame  if (ActRxEvent & RX_OK)  {    if (ActRxEvent & RX_IA) ProcessEthIAFrame();    if (ActRxEvent & RX_BROADCAST) ProcessEthBroadcastFrame();  }  if (TCPFlags & TCP_TIMER_RUNNING)    if (TCPFlags & TIMER_TYPE_RETRY)    {      if (TCPTimer > RETRY_TIMEOUT)      {        TCPRestartTimer();                       // set a new timeout        if (RetryCounter)        {          TCPHandleRetransmission();             // resend last frame          RetryCounter--;        }        else        {          TCPStopTimer();          TCPHandleTimeout();        }      }    }    else if (TCPTimer > FIN_TIMEOUT)    {      TCPStateMachine = CLOSED;      TCPFlags = 0;                              // reset all flags, stop retransmission...      SocketStatus &= SOCK_DATA_AVAILABLE;       // clear all flags but data available    }  switch (TCPStateMachine)  {    case CLOSED :    case LISTENING :    {      if (TCPFlags & TCP_ACTIVE_OPEN)            // stack has to open a connection?        if (TCPFlags & IP_ADDR_RESOLVED)         // IP resolved?          if (!(TransmitControl & SEND_FRAME2))  // buffer free?          {            TCPSeqNr = ((unsigned long)ISNGenHigh << 16) | TAR; // set local ISN            TCPUNASeqNr = TCPSeqNr;            TCPAckNr = 0;                                       // we don't know what to ACK!            TCPUNASeqNr++;                                      // count SYN as a byte            PrepareTCP_FRAME(TCP_CODE_SYN);                     // send SYN frame            LastFrameSent = TCP_SYN_FRAME;            TCPStartRetryTimer();                               // we NEED a retry-timeout            TCPStateMachine = SYN_SENT;          }      break;    }    case SYN_RECD :    case ESTABLISHED :    {      if (TCPFlags & TCP_CLOSE_REQUESTED)                  // user has user initated a close?        if (!(TransmitControl & (SEND_FRAME2 | SEND_FRAME1)))   // buffers free?          if (TCPSeqNr == TCPUNASeqNr)                          // all data ACKed?          {            TCPUNASeqNr++;            PrepareTCP_FRAME(TCP_CODE_FIN | TCP_CODE_ACK);            LastFrameSent = TCP_FIN_FRAME;            TCPStartRetryTimer();            TCPStateMachine = FIN_WAIT_1;          }      break;    }    case CLOSE_WAIT :    {      if (!(TransmitControl & (SEND_FRAME2 | SEND_FRAME1)))     // buffers free?        if (TCPSeqNr == TCPUNASeqNr)                            // all data ACKed?        {          TCPUNASeqNr++;                                        // count FIN as a byte          PrepareTCP_FRAME(TCP_CODE_FIN | TCP_CODE_ACK);        // we NEED a retry-timeout          LastFrameSent = TCP_FIN_FRAME;                        // time to say goodbye...          TCPStartRetryTimer();          TCPStateMachine = LAST_ACK;        }      break;    }  }  if (TransmitControl & SEND_FRAME2)  {    RequestSend(TxFrame2Size);    if (Rdy4Tx())                                // NOTE: when using a very fast MCU, maybe      SendFrame2();                              // the CS8900 isn't ready yet, include    else {                                       // a kind of timer or counter here      TCPStateMachine = CLOSED;      SocketStatus = SOCK_ERR_ETHERNET;          // indicate an error to user      TCPFlags = 0;                              // clear all flags, stop timers etc.    }    TransmitControl &= ~SEND_FRAME2;             // clear tx-flag  }  if (TransmitControl & SEND_FRAME1)  {    PrepareTCP_DATA_FRAME();                     // build frame w/ actual SEQ, ACK....    RequestSend(TxFrame1Size);      if (Rdy4Tx())                                // CS8900 ready to accept our frame?      SendFrame1();                              // (see note above)    else {      TCPStateMachine = CLOSED;      SocketStatus = SOCK_ERR_ETHERNET;          // indicate an error to user      TCPFlags = 0;                              // clear all flags, stop timers etc.    }    TransmitControl &= ~SEND_FRAME1;             // clear tx-flag  }}// easyWEB internal function// handles an incoming broadcast framevoid ProcessEthBroadcastFrame(void){  unsigned int TargetIP[2];  // next two words MUST be read with High-Byte 1st (CS8900 AN181 Page 2)  ReadHB1ST8900(RX_FRAME_PORT);                  // ignore RxStatus Word  RecdFrameLength = ReadHB1ST8900(RX_FRAME_PORT);// get real length of frame       DummyReadFrame8900(6);                         // ignore DA (FF-FF-FF-FF-FF-FF)  CopyFromFrame8900(&RecdFrameMAC, 6);           // store SA (for our answer)  if (ReadFrameBE8900() == FRAME_ARP)            // get frame type, check for ARP    if (ReadFrameBE8900() == HARDW_ETH10)        // Ethernet frame      if (ReadFrameBE8900() == FRAME_IP)         // check protocol        if (ReadFrameBE8900() == IP_HLEN_PLEN)   // check HLEN, PLEN          if (ReadFrameBE8900() == OP_ARP_REQUEST)          {            DummyReadFrame8900(6);               // ignore sender's hardware address            CopyFromFrame8900(&RecdFrameIP, 4);  // read sender's protocol address            DummyReadFrame8900(6);               // ignore target's hardware address            CopyFromFrame8900(&TargetIP, 4);     // read target's protocol address            if (!memcmp(&MyIP, &TargetIP, 4))    // is it for us?              PrepareARP_ANSWER();               // yes->create ARP_ANSWER frame          }}// easyWEB internal function// handles an incoming frame that passed CS8900's address filter// (individual addressed = IA)void ProcessEthIAFrame(void){  unsigned int TargetIP[2];  unsigned char ProtocolType;  // next two words MUST be read with High-Byte 1st (CS8900 AN181 Page 2)  ReadHB1ST8900(RX_FRAME_PORT);                  // ignore RxStatus Word  RecdFrameLength = ReadHB1ST8900(RX_FRAME_PORT);// get real length of frame     DummyReadFrame8900(6);                         // ignore DA  CopyFromFrame8900(&RecdFrameMAC, 6);           // store SA (for our answer)  switch (ReadFrameBE8900())                     // get frame type  {    case FRAME_ARP :                             // check for ARP    {      if ((TCPFlags & (TCP_ACTIVE_OPEN | IP_ADDR_RESOLVED)) == TCP_ACTIVE_OPEN)        if (ReadFrameBE8900() == HARDW_ETH10)         // check for the right prot. etc.          if (ReadFrameBE8900() == FRAME_IP)            if (ReadFrameBE8900() == IP_HLEN_PLEN)              if (ReadFrameBE8900() == OP_ARP_ANSWER)              {                TCPStopTimer();                       // OK, now we've the MAC we wanted ;-)                CopyFromFrame8900(&RemoteMAC, 6);     // extract opponents MAC                TCPFlags |= IP_ADDR_RESOLVED;              }      break;    }    case FRAME_IP :                                        // check for IP-type    {      if ((ReadFrameBE8900() & 0xFF00 ) == IP_VER_IHL)     // IPv4, IHL=5 (20 Bytes Header)      {                                                    // ignore Type Of Service        RecdIPFrameLength = ReadFrameBE8900();             // get IP frame's length        ReadFrameBE8900();                                 // ignore identification        if (!(ReadFrameBE8900() & (IP_FLAG_MOREFRAG | IP_FRAGOFS_MASK)))  // only unfragm. frames