299 lines
7.2 KiB
C
299 lines
7.2 KiB
C
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/*++
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Copyright (c) 1992 Microsoft Corporation
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Module Name:
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slipread.c
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Abstract:
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Author:
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Thomas J. Dimitri (TommyD) 08-May-1992
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Environment:
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Kernel Mode - Or whatever is the equivalent on OS/2 and DOS.
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Revision History:
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--*/
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#include "asyncall.h"
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NTSTATUS
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AsyncWaitMaskCompletionRoutine(
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IN PDEVICE_OBJECT DeviceObject,
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IN PIRP Irp,
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IN PVOID Context);
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NTSTATUS
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AsyncPPPWaitMask(
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IN PASYNC_INFO Info);
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NTSTATUS
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AsyncSLIPCompletionRoutine(
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IN PDEVICE_OBJECT DeviceObject,
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IN PIRP Irp,
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IN PVOID Context)
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/*++
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This is the IO Completion routine for ReadFrame.
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--*/
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{
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NTSTATUS status;
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PASYNC_INFO pInfo;
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ULONG bytesReceived;
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PASYNC_FRAME pFrame;
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PUCHAR frameStart, frameEnd;
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PUCHAR frameEnd2,frameStart2;
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ULONG bitMask;
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LONG bytesWanted; // keep this a long ( < 0 is used)
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DeviceObject; // prevent compiler warnings
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status = Irp->IoStatus.Status;
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bytesReceived=(ULONG)Irp->IoStatus.Information;
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IoFreeIrp(Irp);
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pInfo=Context;
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pFrame=pInfo->AsyncFrame;
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switch (status) {
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case STATUS_SUCCESS:
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//
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// Any bytes to process? This can happen if
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// the WaitMask completes late and by the time
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// we process the read, another event character has come
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// in.
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//
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if (bytesReceived==0) {
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break;
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}
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//
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// Update num of bytes read total for this frame
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//
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pInfo->BytesRead = bytesReceived = pInfo->BytesRead + bytesReceived;
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//
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// Set frameEnd to last byte processed. Initially,
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// we have processed nothing (i.e. processed up to
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// the start of the first byte).
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//
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frameStart=pFrame->Frame + PPP_PADDING;
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PROCESS_FRAME:
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//
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// Now we have actuallyRead bytes unused
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// Also, we may have a complete frame.
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//
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while (*frameStart == SLIP_END_BYTE && --bytesReceived) {
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frameStart++;
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}
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//
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// If we reach here, there is no end FLAG
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//
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if (bytesReceived == 0) {
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break;
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}
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//
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// frameEnd is set to the first byte not yet processed.
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// If we are starting out, that is the first byte!
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//
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frameEnd=frameStart;
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//
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// Assume the start of the frame has the SLIP_END_BYTE
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// Look for the second SLIP_END_BYTE (end of frame)
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//
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while (*frameEnd != SLIP_END_BYTE && --bytesReceived) {
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frameEnd++;
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}
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//
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// if bytesReceived is 0, we got nothing
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//
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// NOTE: if BytesRead gets too high we trash the frame
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// because we could not find the FLAG_BYTE
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//
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if (bytesReceived==0) {
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break;
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}
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if (*(pFrame->Frame+PPP_PADDING) != SLIP_END_BYTE) {
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//
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// We had garbage at the start. Remove the garbage.
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//
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pInfo->SerialStats.AlignmentErrors++;
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//
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// Tell the transport above us that we dropped a packet
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// Hopefully, it will quickly resync.
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//
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AsyncIndicateFragment(
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pInfo,
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WAN_ERROR_ALIGNMENT);
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goto NEXT_SLIP_FRAME;
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}
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//
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// Length of frame is frameEnd - frameStart
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//
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bytesWanted = (LONG)(frameEnd - frameStart);
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bitMask = pInfo->Adapter->WanInfo.DesiredACCM;
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frameEnd2 = frameStart2 = frameStart;
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//
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// Replace back all control chars, ESC, and FLAG chars
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//
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while (bytesWanted-- > 0) {
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if ((*frameEnd2=*frameStart2++) == SLIP_ESC_BYTE) {
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//
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// We have not run the CRC check yet!!
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// We have be careful about sending bytesWanted
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// back to -1 on corrupted data
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//
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bytesWanted--;
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*frameEnd2 = SLIP_END_BYTE;
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if (*frameStart2++ == SLIP_ESC_ESC_BYTE) {
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*frameEnd2 = SLIP_ESC_BYTE;
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}
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}
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frameEnd2++;
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}
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//
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// Change the bytesWanted field to what it normally is,
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// the length of the frame.
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//
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bytesWanted = (LONG)(frameEnd2 - frameStart);
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// Keep those stats up to date
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{
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KIRQL irql;
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NTSTATUS Status;
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PASYNC_ADAPTER Adapter = pInfo->Adapter;
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KeRaiseIrql( (KIRQL)DISPATCH_LEVEL, &irql );
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//
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// Compressed TCP/IP packets must at least 3 bytes long
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//
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if (bytesWanted >= 3) {
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NdisMWanIndicateReceive(
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&Status,
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Adapter->MiniportHandle,
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pInfo->NdisLinkContext,
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frameStart,
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bytesWanted);
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NdisMWanIndicateReceiveComplete(
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Adapter->MiniportHandle,
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pInfo->NdisLinkContext);
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} else {
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pInfo->SerialStats.AlignmentErrors++;
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//
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// Tell the transport above us that we dropped a packet
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// Hopefully, it will quickly resync.
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//
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AsyncIndicateFragment(
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pInfo,
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WAN_ERROR_ALIGNMENT);
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DbgTracef(-2,("SLIP: Frame too small %u\n", bytesWanted));
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}
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KeLowerIrql( irql );
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}
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NEXT_SLIP_FRAME:
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//
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// if bytesReceived == 0 no frame was found
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// thus we must keep the current frame and continue
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// processing
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//
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if (bytesReceived) {
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//
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// Calculate how much of what we received
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// just got passed up as a frame and move the
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// rest to the beginning.
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//
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frameStart=pFrame->Frame + PPP_PADDING;
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frameEnd2=frameStart + pInfo->BytesRead;
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pInfo->BytesRead =
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bytesReceived = (LONG)(frameEnd2-frameEnd);
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ASYNC_MOVE_MEMORY(
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frameStart, // dest
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frameEnd, // src
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bytesReceived); // length
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//
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// Need at least four bytes for a frame to exist
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//
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if (bytesReceived > 3) {
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goto PROCESS_FRAME;
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}
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}
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break;
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case STATUS_CANCELLED:
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// else this is an anomally!
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DbgTracef(-2,("---ASYNC: Status cancelled on read for unknown reason!!\n"));
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break;
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case STATUS_PENDING:
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DbgTracef(0,("---ASYNC: Status PENDING on read\n"));
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break;
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default:
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DbgTracef(-2,("---ASYNC: Unknown status 0x%.8x on read",status));
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break;
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}
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//
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// Here we are at the end of processing this IRP so we go
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// ahead and post another read from the serial port.
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//
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AsyncPPPWaitMask(pInfo);
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// We return STATUS_MORE_PROCESSING_REQUIRED so that the
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// IoCompletionRoutine will stop working on the IRP.
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return(STATUS_MORE_PROCESSING_REQUIRED);
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}
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