tftpc.c

凌阳SPCE3200 系统开发板随机自带源程序。共安排了32个子目录

 *                  server to send next data block.
 *                  If all attempts are exhausted, it returns with
 *                  TFTP_TIMEOUT.
 *
 * Note:            By default, this funciton uses "octet" or binary
 *                  mode of file transfer.
 ********************************************************************/
TFTP_RESULT TFTPIsGetReady(void)
{
    WORD_VAL opCode;
    WORD_VAL blockNumber;
    BOOL bTimeOut;


    // Check to see if timeout has occurred.
    bTimeOut = FALSE;
    if ( TickGetDiff(TickGet(), _tftpStartTick) >= TFTP_GET_TIMEOUT_VAL )
    {
        bTimeOut = TRUE;
        _tftpStartTick = TickGet();
    }

    switch(_tftpState)
    {
    case SM_TFTP_WAIT_FOR_DATA:
        // If timeout occurs in this state, it may be because, we have not
        // even received very first data block or some in between block.
        if ( bTimeOut == TRUE )
        {
            bTimeOut = FALSE;

            if ( _tftpRetries++ > (TFTP_MAX_RETRIES-1) )
            {
                DEBUG(printf("TFTPIsGetReady(): Timeout.\n"));

                // Forget about all previous attempts.
                _tftpRetries = 1;

                return TFTP_TIMEOUT;
            }

            // If we have not even received first block, ask application
            // retry.
            if ( MutExVar.group2._tftpBlockNumber.Val == 1 )
            {
    //            DEBUG(printf("TFTPIsGetReady(): TFTPOpen Retry.\n"));
                return TFTP_RETRY;
            }
            else
            {
                DEBUG(printf("TFTPIsGetReady(): ACK Retry #%d...,\n", _tftpRetries));

                // Block number was already incremented in last ACK attempt,
                // so decrement it.
                MutExVar.group2._tftpBlockNumber.Val--;

                // Do it.
                _tftpState = SM_TFTP_SEND_ACK;
                break;
            }
        }

        // For Read operation, server will respond with data block.
        if ( !UDPIsGetReady(_tftpSocket) )
            break;

        // Get opCode
        UDPGet(&opCode.byte.MSB);
        UDPGet(&opCode.byte.LSB);

        // Get block number.
        UDPGet(&blockNumber.byte.MSB);
        UDPGet(&blockNumber.byte.LSB);

        // In order to read file, this must be data with block number of 0.
        if ( opCode.Val == TFTP_OPCODE_DATA )
        {
            // Make sure that this is not a duplicate block.
            if ( MutExVar.group2._tftpBlockNumber.Val == blockNumber.Val )
            {
                // Mark that we have not acked this block.
                _tftpFlags.bits.bIsAcked = FALSE;

                // Since we have a packet, forget about previous retry count.
                _tftpRetries = 1;

                _tftpState = SM_TFTP_READY;
                return TFTP_OK;
            }

            // If received block has already been received, simply ack it
            // so that Server can "get over" it and send next block.
            else if ( MutExVar.group2._tftpBlockNumber.Val > blockNumber.Val )
            {
                DEBUG(printf("TFTPIsGetReady(): "\
                            "Duplicate block %d received - droping it...\n", \
                            blockNumber.Val));
                MutExVar.group2._tftpDuplicateBlock.Val = blockNumber.Val;
                _tftpState = SM_TFTP_DUPLICATE_ACK;
            }
#if defined(TFTP_DEBUG)
            else
            {
                DEBUG(printf("TFTPIsGetReady(): "\
                             "Unexpected block %d received - droping it...\n", \
                             blockNumber.Val));
            }
#endif
        }
        // Discard all unexpected and error blocks.
        UDPDiscard();

        // If this was an error, remember error code for later delivery.
        if ( opCode.Val == TFTP_OPCODE_ERROR )
        {
            _tftpError = blockNumber.Val;
            return TFTP_ERROR;
        }

        break;

    case SM_TFTP_DUPLICATE_ACK:
        if ( UDPIsPutReady(_tftpSocket) )
        {
            _TFTPSendAck(MutExVar.group2._tftpDuplicateBlock);
            _tftpState = SM_TFTP_WAIT_FOR_DATA;
        }
        break;

    case SM_TFTP_READY:
        if ( UDPIsGetReady(_tftpSocket) )
        {
            _tftpStartTick = TickGet();
            return TFTP_OK;
        }

        // End of file is reached when data block is less than 512 bytes long.
        // To reduce code, only MSB compared against 0x02 (of 0x200 = 512) to
        // determine if block is less than 512 bytes long or not.
        else if ( MutExVar.group2._tftpBlockLength.Val == 0 ||
                  MutExVar.group2._tftpBlockLength.byte.MSB < TFTP_BLOCK_SIZE_MSB )
            _tftpState = SM_TFTP_SEND_LAST_ACK;
        else
            break;


    case SM_TFTP_SEND_LAST_ACK:
    case SM_TFTP_SEND_ACK:
        if ( UDPIsPutReady(_tftpSocket) )
        {
            _TFTPSendAck(MutExVar.group2._tftpBlockNumber);

            // This is the next block we are expecting.
            MutExVar.group2._tftpBlockNumber.Val++;

            // Remember that we have already acked current block.
            _tftpFlags.bits.bIsAcked = TRUE;

            if ( _tftpState == SM_TFTP_SEND_LAST_ACK )
                return TFTP_END_OF_FILE;

            _tftpState = SM_TFTP_WAIT_FOR_DATA;
        }
        break;
    }



    return TFTP_NOT_READY;
}



/*********************************************************************
 * Function:        BYTE TFTPGet(void)
 *
 * PreCondition:    TFTPOpenFile() is called with TFTP_FILE_MODE_READ
 *                  and TFTPIsGetReady() = TRUE
 *
 * Input:           None
 *
 * Output:          data byte as received from remote server.
 *
 * Side Effects:    None
 *
 * Overview:        Fetches next data byte from TFTP socket.
 *                  If end of data block is reached, it issues
 *                  ack to server so that next data block can be
 *                  received.
 *
 * Note:            Use this function to read file from server.
 ********************************************************************/
BYTE TFTPGet(void)
{
    BYTE v = 0;

    // Read byte from UDP
    UDPGet(&v);

    // Update block length
    MutExVar.group2._tftpBlockLength.Val++;

    // Check to see if entire data block is fetched.
    // To reduce code, MSB is compared for 0x02 (of 0x200 = 512).
    if ( MutExVar.group2._tftpBlockLength.byte.MSB == TFTP_BLOCK_SIZE_MSB )
    {
        // Entire block was fetched.  Discard everything else.
        UDPDiscard();

        // Remember that we have flushed this block.
        _tftpFlags.bits.bIsFlushed = TRUE;

        // Reset block length.
        MutExVar.group2._tftpBlockLength.Val = 0;

        // Must send ACK to receive next block.
        _tftpState = SM_TFTP_SEND_ACK;
    }

    return v;
}


/*********************************************************************
 * Function:        void TFTPCloseFile(void)
 *
 * PreCondition:    TFTPOpenFile() was called and TFTPIsFileOpened()
 *                  had returned with TFTP_OK.
 *
 * Input:           None
 *
 * Output:          None
 *
 * Side Effects:    None
 *
 * Overview:        If file is opened in read mode, it makes sure
 *                  that last ACK is sent to server
 *                  If file is opened in write mode, it makes sure
 *                  that last block is sent out to server and
 *                  waits for server to respond with ACK.
 *
 * Note:            TFTPIsFileClosed() must be called to confirm
 *                  if file was really closed.
 ********************************************************************/
void TFTPCloseFile(void)
{
    // If a file was opened for read, we can close it immediately.
    if ( _tftpFlags.bits.bIsReading )
    {
        // If this was premature close, make sure that we discard
        // current block.
        if ( !_tftpFlags.bits.bIsFlushed )
        {
            _tftpFlags.bits.bIsFlushed = TRUE;
            UDPDiscard();
        }

        if ( _tftpFlags.bits.bIsAcked )
        {
            _tftpFlags.bits.bIsClosed = TRUE;
            _tftpFlags.bits.bIsClosing = FALSE;
            return;
        }

        else
        {
            _tftpState = SM_TFTP_SEND_LAST_ACK;
            _tftpFlags.bits.bIsClosing = TRUE;
        }
        return;
    }

    // For write mode, if we have not flushed last block, do it now.
    if ( !_tftpFlags.bits.bIsFlushed )
    {
        _tftpFlags.bits.bIsFlushed = TRUE;
        UDPFlush();
    }

    // For write mode, if our last block was ack'ed by remote server,
    // file is said to be closed.
    if ( _tftpFlags.bits.bIsAcked )
    {
        _tftpFlags.bits.bIsClosed = TRUE;
        _tftpFlags.bits.bIsClosing = FALSE;
        return;
    }

    _tftpState = SM_TFTP_WAIT_FOR_ACK;
    _tftpFlags.bits.bIsClosing =  TRUE;

}



/*********************************************************************
 * Function:        TFTP_RESULT TFPTIsFileClosed(void)
 *
 * PreCondition:    TFTPCloseFile() is already called.
 *
 * Input:           None
 *
 * Output:          TFTP_OK if file was successfully closdd
 *
 *                  TFTP_RETRY if file mode was Write and remote
 *                  server did not receive last packet.
 *                  Application must retry with last block.
 *
 *                  TFTP_TIMEOUT if all attempts were exhausted
 *                  in closing file.
 *
 *                  TFTP_ERROR if remote server sent an error
 *                  in response to last block.
 *                  Actual error code may be read by calling
 *                  TFTPGetError()
 *
 *                  TFTP_NOT_READY if file is not closed yet.
 *
 * Side Effects:    None
 *
 * Overview:        If file mode is Read, it simply makes that
 *                  last block is acknowledged.
 *                  If file mode is Write, it waits for server ack.
 *                  If no ack was received within specified timeout
 *                  instructs appliaction to resend last block.
 *                  It keeps track of retries and declares timeout
 *                  all attempts were exhausted.
 *
 * Note:            None
 ********************************************************************/
TFTP_RESULT TFTPIsFileClosed(void)
{
    if ( _tftpFlags.bits.bIsReading )
        return TFTPIsGetReady();

    else
        return TFTPIsPutReady();
}




/*********************************************************************
 * Function:        TFTP_RESULT TFTPIsPutReady(void)
 *
 * PreCondition:    TFTPOpenFile() is called with TFTP_FILE_MODE_WRITE
 *                  and TFTPIsFileOpened() returned with TRUE.
 *
 * Input:           None
 *
 * Output:          TFTP_OK if it is okay to write more data byte.
 *
 *                  TFTP_TIMEOUT if timeout occurred waiting for
 *                  ack from server
 *
 *                  TFTP_RETRY if all server did not send ack
 *                  on time and application needs to resend
 *                  last block.
 *
 *                  TFTP_ERROR if remote server returned ERROR.
 *                  Actual error code may be read by calling
 *                  TFTPGetError()
 *
 *                  TFTP_NOT_READY if still waiting...
 *
 * Side Effects:    None
 *
 * Overview:        Waits for ack from server.  If ack does not
 *                  arrive within specified timeout, it it instructs
 *                  application to retry last block by returning
 *                  TFTP_RETRY.
 *
 *                  If all attempts are exhausted, it returns with
 *                  TFTP_TIMEOUT.