/*++

Copyright (c) 1992  Microsoft Corporation

Module Name:

    pppread.c

Abstract:


Author:

    Thomas J. Dimitri  (TommyD) 08-May-1992

Environment:

    Kernel Mode - Or whatever is the equivalent on OS/2 and DOS.

Revision History:


--*/

#include "asyncall.h"

NTSTATUS
AsyncSLIPCompletionRoutine(
    IN PDEVICE_OBJECT DeviceObject,
    IN PIRP Irp,
    IN PVOID Context);

NTSTATUS
AsyncWaitMaskCompletionRoutine(
    IN PDEVICE_OBJECT DeviceObject,
    IN PIRP Irp,
    IN PVOID Context);

NTSTATUS
AsyncPPPWaitMask(
    IN PASYNC_INFO Info)

/*++

Assumption -- 0 length frames are not sent (this includes headers)!!!
Also, this is NOT a synchronous operation.  It is always asynchronous.

Routine Description:

    This service writes Length bytes of data from the caller's Buffer to the
    "port" handle.  It is assumed that the handle uses non-buffered IO.

--*/
{
    NTSTATUS            status;
    PIRP                irp;
    PASYNC_FRAME        pFrame;
    PASYNC_ADAPTER      pAdapter=Info->Adapter;

    pFrame=Info->AsyncFrame;

    irp = 
        IoAllocateIrp(Info->DeviceObject->StackSize, (BOOLEAN)FALSE);

    InitSerialIrp(irp,
                  Info,
                  IOCTL_SERIAL_WAIT_ON_MASK,
                  sizeof(ULONG));

    irp->AssociatedIrp.SystemBuffer=&pFrame->WaitMask;

    IoSetCompletionRoutine(
            irp,                            // irp to use
            AsyncWaitMaskCompletionRoutine, // routine to call when irp is done
            Info,                           // context to pass routine
            TRUE,                           // call on success
            TRUE,                           // call on error
            TRUE);                          // call on cancel

    //
    // Now simply invoke the driver at its dispatch entry with the IRP.
    //

    status = IoCallDriver(Info->DeviceObject, irp);

    //
    // Status for a local serial driver should be
    // STATUS_SUCCESS since the irp should complete
    // immediately because there are no read timeouts.
    //
    // For a remote serial driver, it will pend.
    //
    return(status);
}


NTSTATUS
AsyncPPPCompletionRoutine(
    IN PDEVICE_OBJECT DeviceObject,
    IN PIRP Irp,
    IN PVOID Context)

/*++

    This is the IO Completion routine for ReadFrame.

--*/
{
    NTSTATUS        status;
    PASYNC_INFO     pInfo;
    ULONG           bytesReceived;

    PASYNC_FRAME    pFrame;
    PUCHAR          frameStart, frameEnd;
    USHORT          crcData;
    PUCHAR          frameEnd2,frameStart2;
    ULONG           bitMask;
    LONG            bytesWanted;

    DeviceObject;       // prevent compiler warnings

    status = Irp->IoStatus.Status;
    bytesReceived=(ULONG)Irp->IoStatus.Information;

    IoFreeIrp(Irp);

    pInfo=Context;

    pFrame=pInfo->AsyncFrame;

    switch (status) {

    case STATUS_SUCCESS:

        pFrame=pInfo->AsyncFrame;

        //
        // Any bytes to process?  This can happen if
        // the WaitMask completes late and by the time
        // we process the read, another event character has come
        // in.
        //
        if (bytesReceived==0) {
            break;
        }

        //
        // Update num of bytes read total for this frame
        //
        pInfo->BytesRead = bytesReceived = pInfo->BytesRead + bytesReceived;

        //
        // Set frameEnd to last byte processed.  Initially,
        // we have processed nothing (i.e. processed up to
        // the start of the first byte).
        //
        frameStart=pFrame->Frame + PPP_PADDING;

PROCESS_FRAME:
        //
        // Now we have actuallyRead bytes unused
        // Also, we may have a complete frame.
        //
        while (*frameStart == PPP_FLAG_BYTE && --bytesReceived) {
            frameStart++;
        }

        //
        // If we reach here, there is only a start FLAG...
        //
        if (bytesReceived == 0) {
            break;
        }

        //
        // frameEnd is set to the first byte not yet processed.
        // If we are starting out, that is the first byte!
        //
        frameEnd=frameStart;

        //
        // Assume the start of the frame has the PPP_FLAG_BYTE
        // Look for the second PPP_FLAG_BYTE (end of frame)
        //
        while (*frameEnd != PPP_FLAG_BYTE && --bytesReceived) {
            frameEnd++;
        }

        //
        // At this point...
        // frameStart = beginning PPP_FLAG_BYTE seen
        // frameEnd = end PPP_FLAG_BYTE
        // bytesReceived = bytes after frameEnd not processed
        //

        //
        // if bytesReceived is 0, we ran out of space before hitting
        // the END flag.  We will have to wait for the next round
        //
        // NOTE: if BytesRead gets too high we trash the frame
        // because we could not find the FLAG_BYTE
        //
        if (bytesReceived==0) {
            break;
        }
        
        if (*(pFrame->Frame+PPP_PADDING) != PPP_FLAG_BYTE) {

            //
            // We had garbage at the start.  Remove the garbage.
            //
            pInfo->SerialStats.AlignmentErrors++;

            //
            //  Tell the transport above us that we dropped a packet
            //  Hopefully, it will quickly resync.
            //
            AsyncIndicateFragment(
                pInfo,
                WAN_ERROR_ALIGNMENT);


            goto NEXT_PPP_FRAME;
        }

        //
        // Length of frame is frameEnd - frameStart
        //
        bytesWanted = (LONG)(frameEnd - frameStart);


        bitMask = pInfo->Adapter->WanInfo.DesiredACCM;

        frameEnd2 = frameStart2 = frameStart;

        //
        // Replace back all control chars, ESC, and FLAG chars
        //
        while (bytesWanted-- > 0) {
            if ((*frameEnd2=*frameStart2++) == PPP_ESC_BYTE) {

                //
                // We have not run the CRC check yet!!
                // We have be careful about sending bytesWanted
                // back to -1 on corrupted data
                //

                bytesWanted--;

                *frameEnd2 = (*frameStart2++ ^ 0x20);
            }

            frameEnd2++;
        }

        if (*frameStart2 != PPP_FLAG_BYTE) {
            DbgTracef(-2,("BAD PPP FRAME at 0x%.8x  0x%.8x\n", frameStart, frameEnd2));
        }

        //
        // if CRC-16, get 16 bit CRC from end of frame
        //
        frameEnd2 -= 2;

        //
        // Little endian assumptions for CRC
        //
        crcData=(USHORT)frameEnd2[0]+(USHORT)(frameEnd2[1] << 8);
        crcData ^= 0xFFFF;

        //
        // Change the bytesWanted field to what it normally is
        // without the byte stuffing (length of frame between flags)
        // Note that it can be -1 if only one byte was
        // found in between the flag bytes
        //
        bytesWanted = (LONG)(frameEnd2 - frameStart);

        //
        // If we get some sort of garbage inbetween
        // the PPP flags, we just assume it is noise and
        // discard it.  We don't record a PPP CRC error just
        // an alignment error.
        //
        if (bytesWanted < 3) {
            pInfo->SerialStats.AlignmentErrors++;
            //
            //  Tell the transport above us that we dropped a packet
            //  Hopefully, it will quickly resync.
            //
            AsyncIndicateFragment(pInfo, WAN_ERROR_ALIGNMENT);

            goto NEXT_PPP_FRAME;
        }

        //
        // get CRC from FLAG byte to FLAG byte
        //
        if (crcData != CalcCRCPPP(frameStart, bytesWanted)) {

            DbgTracef(0,("---CRC check failed on control char frame!\n"));

            //
            // Record the CRC error
            //
            pInfo->SerialStats.CRCErrors++;

            //
            //  Tell the transport above us that we dropped a packet
            //  Hopefully, it will quickly resync.
            //
            AsyncIndicateFragment(
                pInfo,
                WAN_ERROR_CRC);


            goto NEXT_PPP_FRAME;
        }

/*
        for ( i = 0; (i < (ULONG)bytesWanted) && (i < 48); i++ )
        {
            if ( (i & 15) == 0 )
                DbgTracef(-1, ("\nrx:\t") );
            DbgTracef(-1, ("%.2x ", frameStart[i]) );
        }
        DbgTracef(-1, ("\n") );
*/
    {
        KIRQL               irql;
        NDIS_STATUS         Status;
        PASYNC_ADAPTER      Adapter = pInfo->Adapter;

        KeRaiseIrql( (KIRQL)DISPATCH_LEVEL, &irql );
        //
        // Tell the transport above (or really RasHub) that the connection
        // is now up.  We have a new link speed, frame size, quality of service
        //

        NdisMWanIndicateReceive(&Status,
                               Adapter->MiniportHandle,
                               pInfo->NdisLinkContext,
                               frameStart,              // ptr to start of packet
                               bytesWanted);            // Total packet length  - header
        NdisMWanIndicateReceiveComplete(Adapter->MiniportHandle,
                                       pInfo->NdisLinkContext);

        KeLowerIrql( irql );
    }
    
    NEXT_PPP_FRAME:

        //
        // if bytesReceived == 0 no frame was found
        // thus we must keep the current frame and continue
        // processing
        //
        if (bytesReceived) {

            //
            // Calculate how much of what we received
            // just got passed up as a frame and move the
            // rest to the beginning.
            //
            frameStart=pFrame->Frame + PPP_PADDING;
            frameEnd2=frameStart + pInfo->BytesRead;
            pInfo->BytesRead =
                            bytesReceived = (ULONG)(frameEnd2-frameEnd);

            ASYNC_MOVE_MEMORY(
                frameStart,         // dest
                frameEnd,           // src
                bytesReceived);     // length

            //
            // Need at least four bytes for a frame to exist
            //
            if (bytesReceived > 3) {
                goto PROCESS_FRAME;
            }
        }

        break;

    case STATUS_PENDING:
        DbgTracef(0,("---ASYNC: Status PENDING on read\n"));

    case STATUS_CANCELLED:
        // else this is an anomally!
        DbgTracef(-2,("---ASYNC: Status cancelled on read for unknown reason!!\n"));

    default:
#if DBG
        DbgPrint ("AsyncPPPCompletionRoutine: status == %x, no more reads\n", status) ;
#endif
        return(STATUS_MORE_PROCESSING_REQUIRED);
    }

    //
    // Here we are at the end of processing this IRP so we go
    // ahead and post another read from the serial port.
    //
    AsyncPPPWaitMask(pInfo);

    // We return STATUS_MORE_PROCESSING_REQUIRED so that the
    // IoCompletionRoutine will stop working on the IRP.
    return(STATUS_MORE_PROCESSING_REQUIRED);
}


NTSTATUS
AsyncPPPRead(
    IN PASYNC_INFO Info)


/*++

Assumption -- 0 length frames are not sent (this includes headers)!!!
Also, this is NOT a synchronous operation.  It is always asynchronous.

MUST use non-paged pool to read!!!

Routine Description:

    This service writes Length bytes of data from the caller's Buffer to the
    "port" handle.  It is assumed that the handle uses non-buffered IO.

--*/
{
    NTSTATUS            status;
    PIRP                irp;
    PDEVICE_OBJECT      deviceObject=Info->DeviceObject;
    PFILE_OBJECT        fileObject=Info->FileObject;
    PIO_STACK_LOCATION  irpSp;
    PASYNC_FRAME        pFrame;
    PASYNC_ADAPTER      pAdapter=Info->Adapter;
    PIO_COMPLETION_ROUTINE routine;

    pFrame=Info->AsyncFrame;

    //
    // check if this port is closing down or already closed
    //
    if (Info->PortState == PORT_CLOSING ||
        Info->PortState == PORT_CLOSED) {

        if (Info->PortState == PORT_CLOSED) {
            DbgTracef(-2,("ASYNC: Port closed - but still reading on it!\n"));
        }

        //
        // Acknowledge that the port is closed
        //
        KeSetEvent(&Info->ClosingEvent,     // Event
                   1,                           // Priority
                   (BOOLEAN)FALSE);         // Wait (does not follow)

        //
        // Ok, if this happens, we are shutting down.  Stop
        // posting reads.  Don't make it try to deallocate the irp!
        //
        return(STATUS_MORE_PROCESSING_REQUIRED);
    }

    //
    //  Has our stack counter reached its max?
    //

    if ( Info->ReadStackCounter > 1 ) {

        //
        //  Send off the worker thread to compress this frame
        //
    
        ExInitializeWorkItem(&pFrame->WorkItem,
            (PWORKER_THREAD_ROUTINE) AsyncPPPRead, Info);

        //
        // reset stack counter since we are scheduling
        // a worker thread
        //
        Info->ReadStackCounter=0;

        //
        //  We choose to be nice and use delayed.
        //

        ExQueueWorkItem(&pFrame->WorkItem, DelayedWorkQueue);


        return NDIS_STATUS_PENDING;
    }

    //
    //  One more stack used up.
    //

    Info->ReadStackCounter++;


    // get irp from frame (each frame has an irp allocate with it)

    irp =
        IoAllocateIrp(Info->DeviceObject->StackSize, (BOOLEAN)FALSE);

    // Setup this irp with defaults
    AsyncSetupIrp(pFrame, irp);

    //
    // If we've read all the bytes we can and we still do not
    // have a frame, we trash our buffer and start over
    // again.
    //

    if (Info->BytesRead >= (DEFAULT_EXPANDED_PPP_MAX_FRAME_SIZE - PPP_PADDING)) {

        Info->SerialStats.BufferOverrunErrors++;

        //
        //  Tell the transport above us that we dropped a packet
        //  Hopefully, it will quickly resync.
        //
        AsyncIndicateFragment(Info, WAN_ERROR_BUFFEROVERRUN);

        Info->BytesRead=0;
    }
    
    irp->AssociatedIrp.SystemBuffer =
         pFrame->Frame + Info->BytesRead + PPP_PADDING;


    //
    // Get a pointer to the stack location for the first driver.  This will be
    // used to pass the original function codes and parameters.
    //

    irpSp = IoGetNextIrpStackLocation(irp);
    irpSp->MajorFunction = IRP_MJ_READ;
    irpSp->FileObject = fileObject;
    if (fileObject->Flags & FO_WRITE_THROUGH) {
        irpSp->Flags = SL_WRITE_THROUGH;
    }

    //
    // If this write operation is to be performed without any caching, set the
    // appropriate flag in the IRP so no caching is performed.
    //

    irp->Flags |= IRP_READ_OPERATION;

    if (fileObject->Flags & FO_NO_INTERMEDIATE_BUFFERING) {
        irp->Flags |= IRP_NOCACHE;
    }

    //
    // Copy the caller's parameters to the service-specific portion of the
    // IRP.
    //

    irpSp->Parameters.Read.Length =
        DEFAULT_EXPANDED_PPP_MAX_FRAME_SIZE - Info->BytesRead - PPP_PADDING;

    irpSp->Parameters.Read.Key = 0;                     // we don't use a key
    irpSp->Parameters.Read.ByteOffset = fileObject->CurrentByteOffset;

    if ( Info->GetLinkInfo.SendFramingBits & SLIP_FRAMING ) {

        routine=AsyncSLIPCompletionRoutine;

    } else {

        routine=AsyncPPPCompletionRoutine;
    }

    IoSetCompletionRoutine(
            irp,                            // irp to use
            routine,                        // routine to call when irp is done
            Info,                           // context to pass routine
            TRUE,                           // call on success
            TRUE,                           // call on error
            TRUE);                          // call on cancel

    //
    // We DO NOT insert the packet at the head of the IRP list for the thread.
    // because we do NOT really have an IoCompletionRoutine that does
    // anything with the thread.
    //

    //
    // Now simply invoke the driver at its dispatch entry with the IRP.
    //

    status = IoCallDriver(deviceObject, irp);

    //
    // unroll the stack counter
    //
    if ( Info->ReadStackCounter > 0 ) {

        Info->ReadStackCounter--;
    }

    //
    // Status for a local serial driver should be
    // STATUS_SUCCESS since the irp should complete
    // immediately because there are no read timeouts.
    //
    // For a remote serial driver, it will pend.
    //
    return(status);
}


NTSTATUS
AsyncWaitMaskCompletionRoutine(
    IN PDEVICE_OBJECT DeviceObject,
    IN PIRP Irp,
    IN PVOID Context)

/*++

    This is the IO Completion routine for ReadFrame.

--*/
{
    NTSTATUS        status;
    PASYNC_INFO     pInfo=Context;
    PASYNC_FRAME    pFrame;
    DeviceObject;   // avoid compiler warnings

    status = Irp->IoStatus.Status;
    pFrame=pInfo->AsyncFrame;

    IoFreeIrp(Irp);

    // check if this port is closing down or already closed
    if (pInfo->PortState == PORT_CLOSING ||
        pInfo->PortState == PORT_CLOSED) {

        if (pInfo->PortState == PORT_CLOSED) {
            DbgTracef(-2,("ASYNC: Port closed - but still reading on it!\n"));
        }

        //
        // Acknowledge that the port is closed
        //
        KeSetEvent(
            &pInfo->ClosingEvent,       // Event
            1,                          // Priority
            (BOOLEAN)FALSE);            // Wait (does not follow)

        DbgTracef(1,("ASYNC: PPP no longer holds the wait_on_mask\n"));

        //
        // Ok, if this happens, we are shutting down.  Stop
        // posting reads.  Don't make it try to deallocate the irp!
        //
        return(STATUS_MORE_PROCESSING_REQUIRED);
    }

    // wait failed
    //
    if (status != STATUS_SUCCESS) {

        pInfo->PortState = PORT_FRAMING;

        return(STATUS_MORE_PROCESSING_REQUIRED);
    }

    //
    //  Send off a irp to check comm status
    //  of this port (because we suspect a problem).
    //
    if (pFrame->WaitMask & SERIAL_EV_ERR) {
        AsyncCheckCommStatus(pInfo);
    }

    //
    // Check if RLSD or DSR changed state.
    // If so, we probably have to complete and IRP
    //
    if (pFrame->WaitMask & (SERIAL_EV_RLSD | SERIAL_EV_DSR)) {
        TryToCompleteDDCDIrp(pInfo);
    }

#if DBG
    if (status == STATUS_INVALID_PARAMETER) {

        DbgPrint("ASYNC: PPP BAD WAIT MASK!  Irp is at 0x%.8x\n",Irp);
        DbgBreakPoint();
    }
#endif

    //
    // If we have some more bytes (specifically the event character)
    // in the buffer, let's process those new bytes
    //
    if (pFrame->WaitMask & (SERIAL_EV_RXFLAG | SERIAL_EV_RX80FULL)) {

        //
        // Read current buffer and try to process a frame
        //

        AsyncPPPRead(pInfo);

    } else {
        //
        // Set another WaitMask call
        //
        AsyncPPPWaitMask(pInfo);
    }

    // We return STATUS_MORE_PROCESSING_REQUIRED so that the
    // IoCompletionRoutine will stop working on the IRP.
    return(STATUS_MORE_PROCESSING_REQUIRED);
}