深度剖析WinPcap之(八)——打开与关闭适配器(26)(完)

本文转自 http://eslxf.blog.51cto.com/918801/211973

 

/*#define   BIOCSETBUFFERSIZE 9592

该IOCTL命令码用来设置内核缓冲区大小。

该IOCTL用来设置一个NPF实例的循环缓冲区的大小，当接收到一个BIOCSETBUFFERSIZE命令时，驱动程序释放老的缓冲区，分配一个新的缓冲区，并在OPEN_INSTANCE结构体中复位与该缓冲区相关的所有参数。

当前缓冲的所有数据包都被丢弃。

*/

case BIOCSETBUFFERSIZE:

/*验证输入参数的合法性*/

        if(IrpSp->Parameters.DeviceIoControl.InputBufferLength <

            sizeof(ULONG))

        {          

            SET_FAILURE_BUFFER_SMALL();

            break;

        }

        //获得所需分配缓冲区的字节数

        dim = *((PULONG)Irp->AssociatedIrp.SystemBuffer);

        if (dim / g_NCpu < sizeof(struct PacketHeader))

        {

            dim = 0;

        }

        else

        {

            tpointer = ExAllocatePoolWithTag(NonPagedPool, dim, '6PWA');

            if (tpointer == NULL)

            {//没有内存

                SET_FAILURE_NOMEM();

                break;

            }

        }

 

        /*获得所有缓冲区的锁*/

        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);

        }

 

        /*如果有旧的缓冲区，就释放掉*/

        if (Open->CpuData[0].Buffer != NULL)

        {

            ExFreePool(Open->CpuData[0].Buffer);

        }

/*在OPEN_INSTANCE结构体中复位相关的所有参数*/

        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;

       

        /*释放所有缓冲区的锁*/

        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

该IOCTL命令码用来把用户(packet.dll)所分配的读事件句柄传递给内核层。

参数：HANDLE

参数为size为句柄的大小sizeof(HANDLE)。*/

case BIOCSETEVENTHANDLE:

        /*验证输入参数的合法性*/

        if (IrpSp->Parameters.DeviceIoControl.InputBufferLength !=

sizeof (hUserEvent))

        {

            SET_FAILURE_INVALID_REQUEST();

            break;

        }

   

        hUserEvent = *(PHANDLE)Irp->AssociatedIrp.SystemBuffer;

         /* 对hUserEvent进行访问授权确认，如果访问被授权，就返回该对象体对应的指针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等于NULL，就把Open->ReadEvent赋为pKernelEvent，否则Open->ReadEvent值不改变。*/

        if (InterlockedCompareExchangePointer(&Open->ReadEvent,

pKernelEvent, NULL) != NULL)

       {   //释放pKernelEvent

            ObDereferenceObject(pKernelEvent);

            SET_FAILURE_INVALID_REQUEST();

            break;

        }

        //把ReadEvent复位为非激活状态

        KeResetEvent(Open->ReadEvent);

 

        SET_RESULT_SUCCESS(0);

        break;

…

}