URB

typedef _Struct_size_bytes_(UrbHeader.Length) struct _URB {
    union {
        struct _URB_HEADER
            UrbHeader;
        struct _URB_SELECT_INTERFACE
            UrbSelectInterface;
        struct _URB_SELECT_CONFIGURATION
            UrbSelectConfiguration;
        struct _URB_PIPE_REQUEST
            UrbPipeRequest;
        struct _URB_FRAME_LENGTH_CONTROL
            UrbFrameLengthControl;
        struct _URB_GET_FRAME_LENGTH
            UrbGetFrameLength;
        struct _URB_SET_FRAME_LENGTH
            UrbSetFrameLength;
        struct _URB_GET_CURRENT_FRAME_NUMBER
            UrbGetCurrentFrameNumber;
        struct _URB_CONTROL_TRANSFER
            UrbControlTransfer;

    #if (_WIN32_WINNT >= 0x0600)

        struct _URB_CONTROL_TRANSFER_EX
            UrbControlTransferEx;

    #endif

        struct _URB_BULK_OR_INTERRUPT_TRANSFER
            UrbBulkOrInterruptTransfer;
        struct _URB_ISOCH_TRANSFER
            UrbIsochronousTransfer;
        struct _URB_CONTROL_DESCRIPTOR_REQUEST
            UrbControlDescriptorRequest;
        struct _URB_CONTROL_GET_STATUS_REQUEST
            UrbControlGetStatusRequest;
        struct _URB_CONTROL_FEATURE_REQUEST
            UrbControlFeatureRequest;
        struct _URB_CONTROL_VENDOR_OR_CLASS_REQUEST
            UrbControlVendorClassRequest;
        struct _URB_CONTROL_GET_INTERFACE_REQUEST
            UrbControlGetInterfaceRequest;
        struct _URB_CONTROL_GET_CONFIGURATION_REQUEST
            UrbControlGetConfigurationRequest;

    #if (_WIN32_WINNT >= 0x0501)

        struct _URB_OS_FEATURE_DESCRIPTOR_REQUEST
            UrbOSFeatureDescriptorRequest;
    #endif

    #if (NTDDI_VERSION >= NTDDI_WIN8)

        struct _URB_OPEN_STATIC_STREAMS
            UrbOpenStaticStreams;

    #endif


    #if (NTDDI_VERSION >= NTDDI_WIN10_RS3)


        struct _URB_GET_ISOCH_PIPE_TRANSFER_PATH_DELAYS
            UrbGetIsochPipeTransferPathDelays;

    #endif

    };

} URB, *PURB;

URB是一个其实就是一个大大的联合体，这里使用的是结构体URB_SELECT_CONFIGURATION

struct _URB_SELECT_CONFIGURATION {
    struct _URB_HEADER Hdr;
    PUSB_CONFIGURATION_DESCRIPTOR ConfigurationDescriptor;
    USBD_CONFIGURATION_HANDLE ConfigurationHandle;
    USBD_INTERFACE_INFORMATION Interface;

URB_SELECT_INTERFACE定义如下：

struct _URB_SELECT_INTERFACE {
    struct _URB_HEADER Hdr;
    USBD_CONFIGURATION_HANDLE ConfigurationHandle;
    USBD_INTERFACE_INFORMATION Interface;
};

USBD_INTERFACE_INFORMATION定义如下：

typedef struct _USBD_INTERFACE_INFORMATION {
    USHORT Length;
    UCHAR InterfaceNumber;
    UCHAR AlternateSetting;
    UCHAR Class;
    UCHAR SubClass;
    UCHAR Protocol;
    UCHAR Reserved;
    USBD_INTERFACE_HANDLE InterfaceHandle;
    ULONG NumberOfPipes;
    USBD_PIPE_INFORMATION Pipes[1];
} USBD_INTERFACE_INFORMATION, *PUSBD_INTERFACE_INFORMATION;