CN106656916A - Device and method for switching redirection mode in real time in desktop cloud scene - Google Patents

Abstract

The present invention relates to a method and device for real-time switching of smart card redirection in a desktop cloud scene. The method includes: in the redirection mode of the device interface layer, the application module calls the interface related to the state change of the device, and in the interface When blocking, save the context content corresponding to the interface; based on the disconnection of the virtual machine, the application hook module releases the blocked interface according to the context content, and constructs a message notification that the device is not in place; based on the virtual machine machine connection, the application hook module switches the device redirection mode to API redirection. The invention solves the problem of system abnormality caused by switching redirection mode of the system, improves the user's experience of using the smart card in the desktop cloud scene, and can be applied in the desktop cloud scene.

Description

Device and method for real-time switching of redirection mode in desktop cloud scene

technical field

The invention relates to the field of communication technology, in particular to a redirection method and device.

Background technique

In the security scenario of the desktop cloud, the user needs to use a smart card in the virtual machine for authentication, such as using a smart card (Smart Card) for logging in to the virtual machine. At present, the common technology is to redirect the smart card of the client to the virtual machine for use. The commonly used redirection methods include device interface layer redirection and API (application programming interface) redirection. The device interface layer redirection mainly includes bus redirection and Serial port redirection, parallel port redirection and other corresponding device interface layer redirection.

Device interface layer redirection and API redirection have their own advantages and disadvantages. The device interface layer redirection method can support non-PC/SC standard smart card redirection, and the API redirection method can meet the requirements of both the client and the virtual machine. Requirements for using smart cards. Users need to choose the corresponding redirection method according to different needs, and sometimes they need to switch between the two redirection methods.

In the prior art, device interface layer redirection and API redirection are implemented by two independent modules. 1 is a schematic diagram of a device interface layer redirection method in the prior art, wherein the protocol client 101, the protocol server 102, the virtual USB driver module 103, and the virtual USB driver module 104 are modules that need to be implemented by the protocol manufacturer.

In Figure 1, when using device interface layer redirection, the message processing method for the smart card is as follows:

Steps 1-4, the application module initiates a message, and the message is delivered to the virtual USB driver module implemented by the protocol manufacturer;

Step 5, the virtual USB driver module forwards the message to the transmission module of the protocol server;

Step 6, the message is transmitted through the network through the desktop cloud protocol defined by the manufacturer;

Step 7, after the message arrives at the protocol client, it is handed over to the virtual USB driver module of the client;

Steps 8-10, the client's virtual USB driver module passes the message down, and finally the client's smart card device processes the message and gives a response;

In steps 11-20, the smart card device responds to the message after processing, and finally the message is returned to the application module.

Fig. 2 is a schematic diagram of an API redirection method in the prior art, wherein the protocol client, the protocol server, the smart card resource manager, and the app hook module are modules that need to be implemented by the protocol manufacturer.

In Figure 2, when API redirection is used, the message processing method for the smart card is as follows:

Steps 21-22, the application module initiates a message, and the message is delivered to the app hook module (application injection module) implemented by the protocol manufacturer;

Step 23, the app hook module forwards the message to the transmission module of the protocol server;

Step 24, the message is transmitted through the network using the desktop cloud protocol defined by the manufacturer;

Step 25, after the message arrives at the protocol client, it is handed over to the smart card resource manager of the client;

Steps 26-29, the smart card resource manager transmits the message, and finally the client's smart card device processes the message and gives a response;

In steps 30-38, the smart card device responds to the message after processing, and finally the message is returned to the application module.

The above two redirection methods are essentially intercepting and forwarding messages on message stacks at different levels. No matter which redirection method is used, the application of the virtual machine and the SCard API (smart card API) of the smart card resource manager are the same. stable. When an application module uses a smart card, it usually calls the following messages:

1) The application module calls the SCardEstablishContext interface to establish a context (context), which is used in subsequent interface calls;

2) The application module calls the SCardListCards interface and the Scardlistreaders interface to obtain available card reader information;

3) The application module calls the SCardGetStatusChange interface to query the status of the smart card. If the input timeout parameter is -1, this interface will be blocked until the card status changes (for example, from in-position to out-of-position or out-of-position to in-position). In this case The lower application module usually enables two or more threads, one of which is always blocked for querying the status, and the other threads do corresponding card reading and writing operations;

4) If the smart card is in place and operable, the application module calls the SCardConnect interface to connect to the smart card;

5) The application module calls the SCardTransmit interface to transmit data;

6) After the data transmission, the application module calls the SCardDisconnect interface to release the connection;

7) The application module calls the SCardFreeMemory interface to release the memory;

8) The application module calls the SCardReleaseContext interface to release the context and end the operation;

In the prior art, device interface layer redirection and API redirection are implemented by two independent modules. When switching from one redirection method to another redirection method, it is often necessary to restart the application process. However, for system processes such as Windows winlogon process, LogonUI process, etc., restarting the application process will cause system exceptions, or even a blue screen. Therefore, in the existing technical solutions, if you want to switch the redirection mode, you need to restart the operating system, and you need to modify the files in the virtual machine or modify the registry entries, and you need to restart the virtual machine to take effect, which affects the use. efficiency and user experience.

Contents of the invention

The present invention provides a device and method for switching redirection modes in real time in a desktop cloud scene, so as to improve user experience.

In the first aspect, the present invention provides a redirection mode switching method, and the redirection mode is to redirect a device in a client to a virtual machine. In the method, in the redirection mode of the device interface layer, the application module calls the interface related to the state change of the device, and when the interface is blocked, the context content corresponding to the interface is saved. Then, based on the disconnection of the virtual machine, the application hook module releases the blocking interface according to the context content, and constructs a message notification of the device being out of position. Finally, based on the connection of the virtual machine, the application hook module switches the device redirection mode to API redirection.

In the second aspect, the present invention provides a redirection mode switching method, and the redirection mode is to redirect a device in a client to a virtual machine. In the method, in the API redirection mode, the application module invokes an interface related to the state change of the device, and when the interface needs to be blocked, the application hook module blocks the interface. Then the hook module is used to poll to inquire about the state change of the device, and when the state of the device changes, the blocking interface is released. Based on the disconnection of the virtual machine, a message notification that the device is not in place is constructed. Finally, based on the connection of the virtual machine, the application hook module switches the device redirection mode to device interface layer redirection.

In a third aspect, the present invention provides a redirection switching device, and the redirection method is to redirect a device in a client to a virtual machine. The virtual machine includes an application hook module and an application module. The application module is used to call the interface related to the state change of the device in the redirection mode of the device interface layer. The application hook module is used to save the context content corresponding to the interface when the interface related to the device changing state is blocked; and when the virtual machine is disconnected, release the blocked interface according to the context content, and construct the device out-of-position state message notification. And after connecting to the virtual machine, switch the device redirection method to API redirection.

In a fourth aspect, the present invention provides a redirection switching device, and the redirection method is to redirect a device in a client to a virtual machine. The virtual machine includes an application hook module and an application module. The application module is used in the API redirection mode to call the interface related to the state change of the device. The application hook module is used for blocking the interface related to the device state change when the interface needs to be blocked. And it is used for polling, so as to inquire about the status change of the device, and release the blocked interface when the status of the device changes. And constructing a message notification that the device is not in place when the virtual machine is disconnected; and switching the device redirection mode to device interface layer redirection after the virtual machine is connected.

The device and method for switching the redirection mode provided by the present invention solve the problem that the user needs to restart the virtual machine to switch the redirection mode, reduce the operation time, reduce the difficulty of operation, and solve the problems caused by switching the redirection mode in the system. The problem of system abnormality has improved the user experience of using smart cards in the desktop cloud scene, and the switching of smart cards has been realized immediately.

Preferably, before the application module calls the interface related to the device state change, the application hook module detects whether the system process has loaded a module related to the smart card, and if the application hook module detects that the module related to the smart card has been loaded, then the System process for injection.

Preferably, the interface related to the state change of the device is a smart card acquisition state change interface.

Preferably, the unblocked interface is released by the smart card.

Preferably, the device interface layer redirection is one of bus redirection, serial port redirection, and parallel port redirection.

Preferably, the device is one of a USB smart card, a serial port smart card, and a parallel port smart card.

Description of drawings

FIG. 1 is a schematic diagram of a device interface layer redirection method in the prior art;

FIG. 2 is a schematic diagram of an API redirection method in the prior art;

Fig. 3 is a flow chart of a method for switching from device interface layer redirection to API redirection according to an embodiment of the present invention;

FIG. 4 is a schematic diagram of redirection mode switching according to an embodiment of the present invention;

5 is a flowchart of a method for switching from API redirection to device interface layer redirection according to an embodiment of the present invention;

6 is a schematic diagram of an apparatus for switching from device interface layer redirection to API redirection according to an embodiment of the present invention;

FIG. 7 is a schematic diagram of an apparatus for switching from API redirection to device interface layer redirection according to an embodiment of the present invention.

detailed description

The technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

The redirection mode in the present invention includes device interface layer redirection and API redirection, and the device interface layer redirection is one of device interface layer redirection such as bus redirection, serial port redirection, and parallel port redirection. In the present invention, the device in the client is redirected to the virtual machine, and the device related to the client can be one of smart cards such as a USB smart card, a serial port smart card, and a parallel port smart card, or any other device related to the client. devices, such as printers, etc., the following embodiments will take the client-related device as a smart card as an example to describe the present invention in detail.

The present invention needs to disconnect the virtual machine, release the blocked interface, and construct the message notification of the smart card not in place state when the smart card state change related interface (such as the SCardGetStatusChange interface) is blocked, and to switch the redirection mode. Otherwise, the resource corresponding to the smart card status change interface will not be released, so once the redirection mode is switched at this time, the resource cannot be called normally, and a system exception occurs. Unless the method of restarting the virtual machine in the prior art is adopted, this will bring inconvenience to the user.

Fig. 3 is a flowchart of a method for switching from device interface layer redirection to API redirection according to an embodiment of the present invention.

The following steps 301 to 305 describe how to redirect the smart card of the client to the virtual machine through device interface layer redirection.

S301, start the virtual machine.

S302. The app hook module (application hook module) detects whether a module related to the smart card is loaded in the system process, for example, detects whether the winscard module of the windows system is loaded.

S303. If the app hook module detects that the module related to the smart card has been loaded, perform HOOK (injection) on the system process.

S304. At this time, if the session management module of the virtual machine has not prompted to connect to the virtual machine, all interfaces will return a value, such as the return value SCARD_E_NO_SERVICE, which indicates that the smart card service of the system has not started yet.

S305, if the session management module of the virtual machine prompts to connect to the virtual machine, then the user connects to the virtual machine, and the app hook module detects the current redirection mode, and the redirection mode at this time is device interface layer redirection.

In the device interface layer redirection mode, refer to FIG. 4 for the message processing process in the smart card. Specifically, firstly, the application module initiates a message, and the message is delivered to the virtual USB driver module implemented by the protocol manufacturer. The virtual USB driver module forwards the message to the transmission module of the protocol server. The message is transmitted over the network using the desktop cloud protocol defined by the vendor. Then the message arrives at the protocol client and is handed over to the client's virtual USB driver module. The virtual USB driver module of the client transmits the message, and then the smart card device of the client processes the message and gives a response. Finally, after being processed by the smart card device, a response message is sent to the application module.

S306, all device APIs, such as SCard API (smart card API), all go through the app hook module, and now the app hook module independently enables a thread a to monitor the blocked context (context content), and the context (context content) The correspondence between smart cards, interfaces and blocking situations can be shown.

The following steps S307 to S312 describe how to switch the redirection mode to API redirection in real time.

S307, the app hook module determines whether the user logs in to the virtual machine.

S308, if the user has not logged into the virtual machine, all interfaces return a value, such as the return value SCARD_E_NO_SERVICE, indicating that the smart card service has not started yet.

S309, if the user logs in to the virtual machine, according to the configuration module, the configured redirection mode is device interface layer redirection at this time, then call the interface related to the state change of the smart card, and save the corresponding information corresponding to the interface when the interface is blocked. The context (context content).

In one example, the application module (applications) calls the interface, and calls the SCardGetStatusChange interface (the interface for obtaining the status change of the smart card) to query the status of the smart card. If the input parameter timeout (timeout) has a negative value such as -1, it means that the interface SCardGetStatusChange needs to be blocked. At this moment, the blocking of the interface is completed by the driver, and the apphook module only needs to save the corresponding context (context content) of the interface, and the context (context content) can show the corresponding relationship between the smart card, the interface and the blocked situation. For example, the context shows that the SCardGetStatusChange interface in smart card 1 is blocked, the SCardGetStatusChange interface in smart card 2 is not blocked, the SCardGetStatusChange interface in smart card 3 is blocked, etc.; that is to say, the context shows the blocking of multiple interfaces related to smart card status changes situation; therefore, saving the context is to release the blocked interface according to the information in the context. In one example, if the number of smart cards is multiple, if the redirection method needs to be switched, the multiple smart card redirection methods are switched at the same time, and all of them are switched from device interface layer redirection to API redirection, or at the same time by API redirection. Directed switch to device interface layer redirection. S310, based on the disconnection of the virtual machine, the app hook module (application hook module) releases the blocking interface, and constructs a message notification of the smart card not in place state.

In one example, the user actively disconnects the virtual machine or the protocol message response between the client and the virtual machine times out due to a network abnormality. At this time, thread a monitors the virtual machine disconnection message, and the apphook module releases the blocked SCardGetStatusChange interface. And construct the message notification of smart card pulling out to the application module (applications), that is, the message notification of smart card not in place.

Further, the app hook module uses the SCardCancel (smart card cancellation) interface to release all blocked interfaces.

S311, the application module (applications) calls the SCard API (smart card API), and all interfaces return a value, such as the return value SCARD_E_NO_SERVICE, indicating that the smart card service has not started.

S312, the user reconnects to the virtual machine. According to the configuration information in the configuration module, the app hook module switches the redirection mode of the smart card to API redirection.

In this API redirection mode, see Figure 4 for the message processing process of the smart card. Specifically, firstly, the application module initiates a message, and the message is delivered to the app hook module implemented by the protocol manufacturer. The app hook module forwards the message to the transmission module of the protocol server, and the message is transmitted through the network by using the desktop cloud protocol defined by the manufacturer. The message then arrives at the protocol client and is handed over to the client's smart card resource manager. The smart card resource manager transmits the message, and then the smart card device of the client processes the message and gives a response. Finally, after being processed by the smart card device, a response message is sent to the application module.

FIG. 5 is a flowchart of a method for switching from API redirection to device interface layer redirection according to an embodiment of the present invention.

The following steps 501 to 505 result in how to redirect the smart card of the client to the virtual machine through API redirection.

S501, start the virtual machine.

S502. The app hook module (application hook module) detects whether a module related to the smart card is loaded in the system process, for example, detects whether the winscard module of the windows system is loaded.

S503. If the app hook module detects that the module related to the smart card has been loaded, perform HOOK (injection) on the system process.

S504. At this time, if the session management module of the virtual machine has not prompted to connect to the virtual machine, the apphook module returns a value, such as the return value SCARD_E_NO_SERVICE, which indicates that the smart card service of the system has not started yet.

S505, if the session management module of the virtual machine prompts to connect to the virtual machine, the user connects to the virtual machine, and the app hook module detects the current redirection mode, which is API redirection at this time.

In the API redirection mode, refer to FIG. 4 for the message processing process of the smart card. Specifically, firstly, the application module initiates a message, and the message is delivered to the app hook module implemented by the protocol manufacturer. The app hook module forwards the message to the transmission module of the protocol server, and the message is transmitted through the network by using the desktop cloud protocol defined by the manufacturer. The message then arrives at the protocol client and is handed over to the client's smart card resource manager. The smart card resource manager transmits the message, and then the smart card device of the client processes the message and gives a response. Finally, after being processed by the smart card device, a response message is sent to the application module.

S506, all device APIs, such as SCard API (smart card API), pass through the app hook module. At this time, the app hook module independently enables a thread b to monitor the blocked context (context content), and the context (context content) The correspondence between smart cards, interfaces and blocking situations can be shown.

The following steps S507 to S513 illustrate how to switch the redirection mode to device interface layer redirection in real time.

S507, the app hook module determines whether the user logs in the virtual machine.

S508, if the user has not logged into the virtual machine, all interfaces return a value, such as the return value SCARD_E_NO_SERVICE, indicating that the smart card service has not started yet.

S509, if the user logs in to the virtual machine, according to the configuration module, the configured redirection mode is API redirection at this time, then call the interface related to the state change of the smart card, and when the interface needs to be blocked, the app hook module blocks the interface .

In one example, the application module (applications) calls the interface, and calls the SCardGetStatusChange interface (the interface for obtaining the status change of the smart card) to query the status of the smart card. If the parameter value of the input parameter timeout is -1, it means that the interface SCardGetStatusChange needs to be blocked, and the app hook module blocks this interface. It should be noted that when the SCardGetStatusChange interface needs to be blocked is determined by the system running the smart card, as long as the input parameter timetout sent by the system to the SCardGetStatusChange interface is negative, the SCardGetStatusChange interface needs to be blocked until the smart card status changes.

S510, the app hook module periodically polls to inquire about changes in the state of the smart card, and releases the blocked interface if the state of the smart card changes.

In one example, the app hook module periodically polls to check whether the status of the smart card has changed on the client side. If the smart card changes from the on-position state to the off-position state or from the off-position state to the on-position state, release the blocked SCardGetStatusChange interface.

S511, based on the disconnection of the virtual machine (the user actively disconnects the virtual machine or the protocol message response between the client and the virtual machine times out due to network abnormality), the application module calls the smart card API (SCard API) to construct a message notification that the smart card is not in place , that is, send a message notification that the smart card is not in place to the application module. All interfaces (including the SCardGetStatusChange interface) return a value, such as the return value SCARD_E_NO_SERVICE, indicating that the smart card service has not started.

S512, the user reconnects to the virtual machine. According to the configuration information in the configuration module, the app hook module switches the redirection mode of the smart card to device interface layer redirection.

In this device interface layer redirection mode, refer to Figure 4 for the message processing process in the smart card. Specifically, firstly, the application module initiates a message, and the message is delivered to the virtual USB driver module implemented by the protocol manufacturer. The virtual USB driver module forwards the message to the transmission module of the protocol server. The message is transmitted over the network using the desktop cloud protocol defined by the vendor. Then the message arrives at the protocol client and is handed over to the client's virtual USB driver module. The virtual USB driver module of the client transmits the message, and then the smart card device of the client processes the message and gives a response. Finally, after being processed by the smart card device, a response message is sent to the application module.

Fig. 6 is a schematic diagram of an apparatus for switching from device interface layer redirection to API redirection according to an embodiment of the present invention.

The client redirects the smart card in the client to a virtual machine through the network, and the smart card is inserted into the client. The virtual machine includes an app hook module 601 (application hook module 601), a configuration module 602, a session management module 603, an application Module 604.

The application module 604 is used for invoking an interface related to the status change of the smart card when the virtual machine is logged in.

The app hook module 601 is used to save the context content (context) corresponding to the interface when the interface related to the change state of the smart card needs to be blocked; the app hook module 601 is also used to release the blocked interface when the virtual machine is disconnected Blocking the interface, and constructing a message notification that the smart card is not in place; and switching the smart card redirection mode to API redirection after the virtual machine is connected.

The session management module 603 is used to prompt the user that the virtual machine has been connected.

The configuration module 602 is used to provide configuration information, including configuration information switched from device interface layer redirection to API redirection, configuration information switched from API redirection to device interface layer redirection, configuration information of device interface layer redirection, Configuration information for API redirection, etc.

Further, after the virtual machine is started, the app hook module 601 is also used to detect whether the system process has loaded a module related to the smart card (such as detecting whether the winscard module of the windows system is loaded), and if the module is loaded, the The system process performs HOOK (injection).

Further, the app hook module 601 is also used to start a thread to monitor the blocked context (context content).

Further, the app hook module 601 is also used to determine whether the user has logged into the virtual machine.

Further, the app hook module 601 is also used for releasing the blocked interface, and constructing a message notification of the smart card not in place state.

Further, the application module 604 is used to call the SCardGetStatusChange interface (a smart card acquisition status change interface) to query the status of the smart card.

Fig. 7 is a schematic diagram of an apparatus for switching from API redirection to device interface layer redirection according to an embodiment of the present invention.

The client redirects the smart card in the client to the virtual machine through the network, the smart card is inserted into the client, and the virtual machine includes an app hook module 701 (application hook module 701), a configuration module 702, a session management module 703, an application Module 704.

The application module 704 is used to call an interface related to the status change of the smart card when the virtual machine is logged in.

The app hook module 701 is used to block the interface related to the status change of the smart card when the interface needs to be blocked; and is used for regular polling to inquire about the status change of the smart card, and when the status of the smart card changes, release the interface. Blocking the interface; and constructing a message notification that the smart card is not in place when the virtual machine is disconnected; and switching the smart card redirection mode to device interface layer redirection after the virtual machine is connected.

The session management module 703 is used to prompt the user that the virtual machine has been connected.

The configuration module 702 is used to provide configuration information, including switching from device interface layer redirection to API redirection, switching from API redirection to device interface layer redirection, only device interface layer redirection, only API redirection, and so on.

Further, the app hook module 701 is also used to detect whether the system process has loaded a module related to the smart card (such as detecting whether the winscard module of the windows system is loaded) after the virtual machine is started. If the module is loaded, the The system process performs HOOK (injection).

Further, the app hook module 701 is also used to start a thread to monitor the blocked context (context content).

Further, the app hook module 701 is also used to determine whether the user has logged into the virtual machine.

Further, the application module 704 is also used to call a smart card API (SCard API) after the virtual machine is disconnected.

Further, the application module 704 is also used to call the SCardGetStatusChange interface (a smart card acquisition status change interface) to query the status of the smart card.

To sum up, switching the redirection mode in the present invention can be realized only after the user disconnects the virtual machine and then connects to the virtual machine, and does not require the user to restart the virtual machine. In the prior art, if the redirection mode needs to be switched, the virtual machine needs to be hot-started and the user needs to modify the file corresponding to the new redirection mode in the virtual machine or the user needs to modify the registry entry. In addition, reconnecting the virtual machine takes shorter operation time and better user experience than warm-starting the virtual machine.

In the foregoing embodiments, the descriptions of each embodiment have their own emphases, and for parts not described in detail in a certain embodiment, reference may be made to relevant descriptions of other embodiments.

Professionals should further realize that the units and algorithm steps described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the relationship between hardware and software Interchangeability. In the above description, the composition and steps of each example have been generally described according to their functions. Whether these functions are executed by hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be regarded as exceeding the scope of the present invention.

The steps of the methods or algorithms described in connection with the embodiments disclosed herein may be implemented by hardware, software modules executed by a processor, or a combination of both. Software modules can be placed in random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any Any other known storage medium.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention and are not intended to limit the scope of the present invention. Protection scope, within the spirit and principles of the present invention, any modification, equivalent replacement, improvement, etc., shall be included in the protection scope of the present invention.

Claims (18)

1. a kind of redirection mode changing method, wherein, the redirection mode is by the equipment in client Virtual machine is redirected to, the method includes：

Step a, under device interface layer redirection mode, application module is called and equipment state change Related interface, and when the interface blocks, preserve context corresponding with the interface；

Step b, based on the disconnection of the virtual machine, discharges using hook module according to the context The blocking interface, and construct the message informing of equipment state not in place；

Step c, based on the connection of the virtual machine, the application hook module is by the device redirection mode Switch to API redirections.

2. redirection mode changing method according to claim 1, it is characterised in that the equipment The related interface of state change is that smart card obtains state change interface.

3. redirection mode changing method according to claim 1 and 2, it is characterised in that in institute In stating step b, interface is cancelled by smart card and discharges the blocking interface.

4. the redirection mode changing method according to one of claims 1 to 3, it is characterised in that It is complete by system drive when the interface needs blocked when the interface blocks in step a The obstruction of the paired interface.

5. the redirection mode changing method according to one of Claims 1-4, it is characterised in that The context is illustrated that, the equipment, the corresponding relation between interface and congestion situations.

6. the redirection mode changing method according to one of claim 1 to 5, it is characterised in that Also include before step c after step b：

Application module calls smart card API, total interface to return a numerical value, to represent the equipment clothes Business does not start.

7. a kind of redirection mode changing method, wherein, the redirection mode is by the equipment in client Virtual machine is redirected to, the method includes：

Step d, under API redirection modes, application module calls related to equipment state change Interface, and when the interface needs obstruction, using hook module the interface is blocked；

Step e, the application hook module poll, to inquire about the equipment state situation of change, and at this When equipment state changes, the blocking interface is discharged；

Step f, based on the disconnection of virtual machine, constructs equipment message informing not in place；

Step g, based on the connection of the virtual machine, the application hook module is by the device redirection mode Switch to device interface layer redirection.

8. redirection mode changing method according to claim 7, it is characterised in that the equipment The related interface of state change is that smart card obtains state change interface.

9. the redirection mode changing method according to claim 7 or 8, it is characterised in that in institute In stating step b, interface is cancelled by smart card and discharges the blocking interface

10. the redirection changing method according to one of claim 7 to 9, it is characterised in that Include after step f, total interface returns a value, to represent that the device service not yet starts.

A kind of 11. redirection switching devices, wherein, the redirection mode is by the equipment weight in client It is directed to virtual machine, it is characterised in that the virtual machine is included using hook module, application module；

The application module is used to call and equipment state change under device interface layer redirection mode Related interface；

The application hook module be used for it is described block with equipment variations state relevant interface when, preserve with The corresponding context of the interface；And under virtual machine disconnection, according to the context The blocking interface is discharged, the message informing of equipment state not in place is constructed；And after the virtual machine is connected, Device redirection mode is switched to into API to redirect.

12. redirection mode switching devices according to claim 11, it is characterised in that described to set The related interface of standby state change is that smart card obtains state change interface.

The 13. redirection mode switching devices according to claim 11 or 12, it is characterised in that The application hook module cancels interface and discharges the blocking interface by smart card.

The 14. redirection mode switching devices according to one of claim 11 to 13, its feature exists In described is by system drive when the interface needs blocked with equipment variations state relevant interface obstruction Complete the obstruction to the interface.

The 15. redirection mode switching devices according to one of claim 11 to 14, its feature exists In the context is illustrated that, the equipment, the correspondence pass between interface and congestion situations System.

A kind of 16. redirection switching devices, wherein, the redirection mode is by the equipment weight in client It is directed to virtual machine, it is characterised in that the virtual machine is included using hook module, application module；

The application module is related to equipment state change for calling under API redirection modes Interface；

The application hook module is used to block when described and equipment variations state relevant interface needs obstruction The interface；And for poll, to inquire about the equipment state situation of change, and occur in the equipment state During change, the blocked interface is discharged；And construct that the equipment is not in place to disappear when virtual machine disconnects Breath is notified；And for after the virtual machine is connected, the device redirection mode being switched to into device interface layer Redirect.

17. redirection mode switching devices according to claim 16, it is characterised in that described to set The related interface of standby state change is that smart card obtains state change interface.

The 18. redirection mode switching devices according to claim 16 or 17, it is characterised in that Interface is cancelled by smart card when described and equipment variations state same-interface needs obstruction and discharges the obstruction Interface.