驱动开发之五 --- TDI之三【译文】

转自 http://hi.baidu.com/combojiang/blog/item/60b25710f7c7a004213f2ec4.html

接上

步骤2：打开连接上下文

第二步是打开连接上下文。在你建立的连接中，执行后续的操作会用到这个句柄。这也是由ZwCreateFile完成，也是在相同的设备 " \Device\Tcp " 上执行。实际上这个设备允许你打开三个不同的句柄。这三个句柄是传输句柄，连接上下文句柄和控制句柄。需要注意一个常犯的错误的是，一个句柄打开成功，但实际上确是一个错误打开的句柄。这是由于他们是由 " Extended Attributes " 来决定打开哪个句柄的。显然，如果驱动程序不能识别EA（ " Extended Attributes " ）的值，那么它就会打开一个默认的句柄类型，控制句柄。这是MSDN中关于创建部分的文档描述的。

下面的代码演示了打开一个连接上下文。注意你需要制定一个 " CONNECTION_CONTEXT " 类型的指针，使用这个指针指向用户定义的数据。后面你会注意到一些事件回调会提供这个指针给你。这也是你可以使用这个上下文值的本质。

NTSTATUS TdiFuncs_OpenConnection(PHANDLE pTdiHandle, PFILE_OBJECT * pFileObject)

{

NTSTATUS NtStatus = STATUS_INSUFFICIENT_RESOURCES;

UNICODE_STRING usTdiDriverNameString;

OBJECT_ATTRIBUTES oaTdiDriverNameAttributes;

IO_STATUS_BLOCK IoStatusBlock;

char DataBlob[sizeof(FILE_FULL_EA_INFORMATION) +

TDI_CONNECTION_CONTEXT_LENGTH + 300] =

{0};

PFILE_FULL_EA_INFORMATION pExtendedAttributesInformation =

(PFILE_FULL_EA_INFORMATION)&DataBlob;

UINT dwEASize = 0;

/**//*

* Initialize the name of the device to be opened. ZwCreateFile

* takes an OBJECT_ATTRIBUTES structure as the name of the device

* to open. This is then a two step process.

* 1 - Create a UNICODE_STRING data structure from a unicode string.

* 2 - Create a OBJECT_ATTRIBUTES data structure from a UNICODE_STRING.

RtlInitUnicodeString(&usTdiDriverNameString, L"\\Device\\Tcp");

InitializeObjectAttributes(&oaTdiDriverNameAttributes,

&usTdiDriverNameString,

OBJ_CASE_INSENSITIVE | OBJ_KERNEL_HANDLE,

NULL, NULL);

/**//*

* The second step is to initialize the Extended Attributes data structure.

* EaName = TdiConnectionContext, 0, Your User Defined Context Data

* (Actually a pointer to it)

* EaNameLength = Length of TdiConnectionContext

* EaValueLength = Entire Length

RtlCopyMemory(&pExtendedAttributesInformation->EaName,

TdiConnectionContext, TDI_CONNECTION_CONTEXT_LENGTH);

pExtendedAttributesInformation->EaNameLength =

TDI_CONNECTION_CONTEXT_LENGTH;

pExtendedAttributesInformation->EaValueLength =

TDI_CONNECTION_CONTEXT_LENGTH;

/**//* Must be at least TDI_CONNECTION_CONTEXT_LENGTH */

dwEASize = sizeof(DataBlob);

NtStatus = ZwCreateFile(pTdiHandle,

FILE_READ_EA | FILE_WRITE_EA, &oaTdiDriverNameAttributes,

&IoStatusBlock, NULL,

FILE_ATTRIBUTE_NORMAL, 0, FILE_OPEN_IF, 0,

pExtendedAttributesInformation, dwEASize);

if(NT_SUCCESS(NtStatus))

{

NtStatus = ObReferenceObjectByHandle(*pTdiHandle,

GENERIC_READ | GENERIC_WRITE,

NULL, KernelMode,

(PVOID *)pFileObject, NULL);

if(!NT_SUCCESS(NtStatus))

{

ZwClose(*pTdiHandle);

}

return NtStatus;

}

步骤3：关联传输地址和连接上下文

在你执行任何操作之前，你需要关联这两个句柄，传输句柄和连接上下文句柄。这个通过给设备发送一个IOCTL来完成。是否你还记得先前我们是怎样发送IOCTL的？我们需要分配一个IRP,设置参数和发送它到设备。由于TDI头文件提供了宏和其他的函数可以帮助我们简化这个步骤。TdiBuildInternalDeviceControlIrp实际是一个宏，它内部调用了IoBuildDeviceIoControlRequest. 给这个宏的一些参数实际被忽略了，但是对于注释来讲还是有用的（就像提供的IOCTL一样）。这个API很简单，我们为了演示目的使用它。然而使用其它机制来创建IRP，就像IoAllocateIrp，有一些优点，这个将在后面叙述。其他的宏被用于给底层的驱动简单的设置IO_STACK_LOCATION的参数。

这里有一件事情你需要注意，这里跟我们上次谈到的有些不同的是 " STATUS_PENDING " 。本篇后面将会讨论这个。

下面的代码演示如何使用它。

NTSTATUS TdiFuncs_AssociateTransportAndConnection(HANDLE hTransportAddress,

PFILE_OBJECT pfoConnection)

{

NTSTATUS NtStatus = STATUS_INSUFFICIENT_RESOURCES;

PIRP pIrp;

IO_STATUS_BLOCK IoStatusBlock =

{0};

PDEVICE_OBJECT pTdiDevice;

TDI_COMPLETION_CONTEXT TdiCompletionContext;

KeInitializeEvent(&TdiCompletionContext.kCompleteEvent,

NotificationEvent, FALSE);

/**//*

* The TDI Device Object is required to send these

* requests to the TDI Driver.

pTdiDevice = IoGetRelatedDeviceObject(pfoConnection);

/**//*

* Step 1: Build the IRP. TDI defines several macros and functions

* that can quickly create IRP's, etc. for variuos purposes.

* While this can be done manually it's easiest to use the macros.

* http://msdn.microsoft.com/library/en-us/network/hh/network/

* 34bldmac_f430860a-9ae2-4379-bffc-6b0a81092e7c.xml.asp?frame=true

pIrp = TdiBuildInternalDeviceControlIrp(TDI_ASSOCIATE_ADDRESS,

pTdiDevice, pfoConnection, &TdiCompletionContext.kCompleteEvent,

&IoStatusBlock);

if(pIrp)

{

/**//*

* Step 2: Add the correct parameters into the IRP.

TdiBuildAssociateAddress(pIrp, pTdiDevice,

pfoConnection, NULL, NULL, hTransportAddress);

NtStatus = IoCallDriver(pTdiDevice, pIrp);

/**//*

* If the status returned is STATUS_PENDING this means that the IRP

* will not be completed synchronously and the driver has queued the

* IRP for later processing. This is fine but we do not want

* to return this thread, we are a synchronous call so we want

* to wait until it has completed. The EVENT that we provided will

* be set when the IRP completes.

if(NtStatus == STATUS_PENDING)

{

KeWaitForSingleObject(&TdiCompletionContext.kCompleteEvent,

Executive, KernelMode, FALSE, NULL);

/**//*

* Find the Status of the completed IRP

NtStatus = IoStatusBlock.Status;

}

return NtStatus;

}

驱动开发之五 --- TDI之三 【译文】