/*#define BIOCSETBUFFERSIZE 9592
該IOCTL命令碼用來設置內核緩衝區大小。
該IOCTL用來設置一個NPF實例的循環緩衝區的大小，當接收到一個BIOCSETBUFFERSIZE命令時，驅動程序釋放老的緩衝區，分配一個新的緩衝區，並在OPEN_INSTANCE結構體中復位與該緩衝區相關的所有參數。
當前緩衝的所有數據包都被丟棄。
*/
case BIOCSETBUFFERSIZE:
/*驗證輸入參數的合法性*/
if(IrpSp->Parameters.DeviceIoControl.InputBufferLength <
sizeof(ULONG))
{
SET_FAILURE_BUFFER_SMALL();
break;
}
//獲得所需分配緩衝區的字節數
dim = *((PULONG)Irp->AssociatedIrp.SystemBuffer);
if (dim / g_NCpu < sizeof(struct PacketHeader))
{
dim = 0;
}
else
{
tpointer = ExAllocatePoolWithTag(NonPagedPool, dim, '6PWA');
if (tpointer == NULL)
{//沒有內存
SET_FAILURE_NOMEM();
break;
}
}
/*獲得所有緩衝區的鎖*/
for (i = 0; i < g_NCpu ; i++)
{
#pragma prefast(suppress:8103,
"There's no Spinlock leak here, as it's released some lines below.")
NdisAcquireSpinLock(&Open->CpuData[i].BufferLock);
}
/*如果有舊的緩衝區，就釋放掉*/
if (Open->CpuData[0].Buffer != NULL)
{
ExFreePool(Open->CpuData[0].Buffer);
}
/*在OPEN_INSTANCE結構體中復位相關的所有參數*/
for (i = 0 ; i < g_NCpu ; i++)
{
if (dim > 0)
Open->CpuData[i].Buffer=
(PUCHAR)tpointer + (dim/g_NCpu)*i;
else
Open->CpuData[i].Buffer = NULL;
Open->CpuData[i].Free = dim/g_NCpu;
Open->CpuData[i].P = 0;
Open->CpuData[i].C = 0;
Open->CpuData[i].Accepted = 0;
Open->CpuData[i].Dropped = 0;
Open->CpuData[i].Received = 0;
}
Open->ReaderSN=0;
Open->WriterSN=0;
Open->Size = dim/g_NCpu;
/*釋放所有緩衝區的鎖*/
i = g_NCpu;
do
{
i--;
#pragma prefast(suppress:8107,
"There's no Spinlock leak here, as it's acquired some lines above.")
NdisReleaseSpinLock(&Open->CpuData[i].BufferLock);
}while(i != 0);
SET_RESULT_SUCCESS(0);
break;
/*#define BIOCSETEVENTHANDLE 7920
該IOCTL命令碼用來把用戶(packet.dll)所分配的讀事件句柄傳遞給內核層。
參數：HANDLE
參數爲size爲句柄的大小sizeof(HANDLE)。*/
case BIOCSETEVENTHANDLE:
/*驗證輸入參數的合法性*/
if (IrpSp->Parameters.DeviceIoControl.InputBufferLength !=
sizeof (hUserEvent))
{
SET_FAILURE_INVALID_REQUEST();
break;
}
hUserEvent = *(PHANDLE)Irp->AssociatedIrp.SystemBuffer;
/* 對hUserEvent進行訪問授權確認，如果訪問被授權，就返回該對象體對應的指針pKernelEvent。*/
Status = ObReferenceObjectByHandle(hUserEvent,
EVENT_MODIFY_STATE, *ExEventObjectType, Irp->RequestorMode,
(PVOID*) &pKernelEvent, NULL);
if (!NT_SUCCESS(Status))
{
// Status = ??? already set
Information = 0;
break;
}
/* 如果&Open->ReadEvent等於NULL，就把Open->ReadEvent賦爲pKernelEvent，否則Open->ReadEvent值不改變。*/
if (InterlockedCompareExchangePointer(&Open->ReadEvent,
pKernelEvent, NULL) != NULL)
{ //釋放pKernelEvent
ObDereferenceObject(pKernelEvent);
SET_FAILURE_INVALID_REQUEST();
break;
}
//把ReadEvent復位爲非激活狀態
KeResetEvent(Open->ReadEvent);
SET_RESULT_SUCCESS(0);
break;
…
}
說明：
深度剖析WinPcap之(八)章節全部結束。