An information update method, device, electronic device and storage medium

Abstract

An embodiment of the present invention provides an information update method, device, electronic device, and storage medium, which relate to the field of communication technologies. The method includes: sending a DHCP request message carrying a to-be-verified IP address to a DHCP server; if a DHCP response message for the DHCP request message sent by the DHCP server is not received within a first preset time period after sending the DHCP request message, sending a reachability verification message to the DHCP server; if a reachability response message sent by the DHCP server is received within a second preset time period after sending the reachability verification message, deleting the to-be-verified client information to which the to-be-verified IP address belongs. In this way, the security of services can be ensured.

Description

Technical Field

[0001] The present invention relates to the field of communication technologies, and in particular, to an information update method, apparatus, electronic device, and storage medium. Background Art

[0002] DHCP (Dynamic Host Configuration Protocol) is a network protocol for a local area network. A DHCP network consists of a DHCP server, a DHCP relay, and a DHCP client.

[0003] A DHCP client can request a dynamic IP (Internet Protocol) address from a DHCP server through a DHCP relay. The DHCP relay can record client information of the DHCP client, including information such as the IP address and MAC (Media Access Control) address of the DHCP client.

[0004] During the business processing, to improve the security of the business, the DHCP relay can verify the received packets according to the recorded client information and forward the packets that pass the verification. Since the IP address assigned by the DHCP server to the DHCP client has a certain validity period, therefore, how to effectively update the recorded client information to ensure the security of the business has become an urgent problem to be solved. Summary of the Invention

[0005] The purpose of the embodiments of the present invention is to provide an information update method, apparatus, electronic device, and storage medium to ensure the security of the business. The specific technical solutions are as follows:

[0006] In the first aspect of the embodiments of the present application, first, an information update method is provided. The method includes:

[0007] Sending a DHCP request packet carrying an Internet Protocol (IP) address to be verified to a Dynamic Host Configuration Protocol (DHCP) server; wherein, the IP address to be verified represents the IP address in any client information to be verified recorded.

[0008] If within a first preset time period after sending the DHCP request packet, a DHCP response packet for the DHCP request packet sent by the DHCP server is not received, then sending a reachability verification packet to the DHCP server.

[0009] If a reachability response packet sent by the DHCP server is received within a second preset time period after sending the reachability verification packet, then deleting the client information to be verified to which the IP address to be verified belongs.

[0010] In some embodiments, the method further includes:

[0011] If an reachability response message sent by the DHCP server is not received within a second preset duration after sending the reachability verification message, return to execute the step of sending a DHCP request message carrying the IP address to be verified to the DHCP server until a preset stop time is reached, and delete the client information to be verified of the IP address to be verified; wherein, the preset stop time indicates: the time obtained by extending the time corresponding to the first sending of the reachability verification message by the preset retention duration corresponding to the client information to be verified.

[0012] In some embodiments, the method further includes:

[0013] If an reachability response message sent by the DHCP server is not received within a second preset duration after sending the reachability verification message, determine whether the client information of the recorded online clients contains the client information to be verified of the IP address to be verified.

[0014] If the client information of the recorded online clients does not contain the client information to be verified of the IP address to be verified, delete the client information to be verified of the IP address to be verified.

[0015] In some embodiments, the method further includes:

[0016] If the client information of the recorded online clients contains the client information to be verified of the IP address to be verified, return to execute the step of sending a DHCP request message carrying the IP address to be verified to the DHCP server.

[0017] In some embodiments, the method further includes:

[0018] If an reachability response message sent by the DHCP server is not received within a second preset duration after sending the reachability verification message, and there is currently a preset retention duration corresponding to the client information to be verified, return to execute the step of sending a DHCP request message carrying the IP address to be verified to the DHCP server until a preset stop time is reached, and then delete the client information of the IP address to be verified; wherein, the preset stop time indicates: the time obtained by extending the time corresponding to the first sending of the reachability verification message by the preset retention duration corresponding to the client information to be verified;

[0019] If, within a second preset duration after sending the reachability verification message, the reachability response message sent by the DHCP server is not received, and there is no preset retention duration corresponding to the client information to be verified currently, determine whether the client information of the online clients recorded contains the client information to be verified to which the IP address to be verified belongs; if not, delete the client information to be verified to which the IP address to be verified belongs.

[0020] In some embodiments, the method further includes:

[0021] If, within a first preset duration after sending the DHCP request message, the DHCP-ACK message for the DHCP request message sent by the DHCP server is received, delete the client information to be verified to which the IP address to be verified belongs.

[0022] In some embodiments, the DHCP response message includes: DHCP-ACK message and DHCP-NAK message.

[0023] In the second aspect of the embodiments of the present application, an information update device is provided, and the device includes:

[0024] A first message sending module, configured to send a DHCP request message carrying an IP address to be verified to a Dynamic Host Configuration Protocol (DHCP) server; wherein, the IP address to be verified represents the IP address in any client information to be verified recorded.

[0025] A second message sending module, configured to send a reachability verification message to the DHCP server if, within a first preset duration after sending the DHCP request message, the DHCP response message for the DHCP request message sent by the DHCP server is not received.

[0026] A first deletion module, configured to delete the client information to be verified to which the IP address to be verified belongs if, within a second preset duration after sending the reachability verification message, the reachability response message sent by the DHCP server is received.

[0027] In some embodiments, the device further includes:

[0028] A first processing module, configured to trigger the first message sending module until a preset stop time is reached and delete the client information to be verified to which the IP address to be verified belongs if, within a second preset duration after sending the reachability verification message, the reachability response message sent by the DHCP server is not received; wherein, the preset stop time represents: the time obtained by extending the time corresponding to the preset retention duration of the client information to be verified backward from the time when the reachability verification message is sent for the first time.

[0029] In some embodiments, the apparatus further comprises:

[0030] An online judgment module, configured to, if within a second preset duration after sending the reachability verification message, the reachability response message sent by the DHCP server is not received, judge whether the client information of the to-be-verified client to which the to-be-verified IP address belongs exists in the client information of the recorded online clients;

[0031] A second processing module, configured to, if the client information of the to-be-verified client to which the to-be-verified IP address belongs does not exist in the client information of the recorded online clients, delete the client information of the to-be-verified client to which the to-be-verified IP address belongs.

[0032] In some embodiments, the apparatus further comprises:

[0033] A third processing module, configured to, if the client information of the to-be-verified client to which the to-be-verified IP address belongs exists in the client information of the recorded online clients, trigger the first message sending module.

[0034] In some embodiments, the apparatus further comprises:

[0035] A fourth processing module, configured to, if within a second preset duration after sending the reachability verification message, the reachability response message sent by the DHCP server is not received, and a preset retention duration corresponding to the to-be-verified client information currently exists, trigger the first message sending module until a preset stop moment is reached, and then delete the client information of the to-be-verified client to which the to-be-verified IP address belongs; wherein, the preset stop moment means: the moment obtained by extending the moment of first sending the reachability verification message by the time corresponding to the preset retention duration of the to-be-verified client information;

[0036] A fifth processing module, configured to, if within a second preset duration after sending the reachability verification message, the reachability response message sent by the DHCP server is not received, and the preset retention duration corresponding to the to-be-verified client information does not currently exist, judge whether the client information of the to-be-verified client to which the to-be-verified IP address belongs exists in the client information of the recorded online clients; if not, delete the client information of the to-be-verified client to which the to-be-verified IP address belongs.

[0037] In some embodiments, the apparatus further comprises:

[0038] A second deletion module, configured to, if within a first preset duration after sending the DHCP request message, the DHCP-ACK message sent by the DHCP server for the DHCP request message is received, delete the client information of the to-be-verified client to which the to-be-verified IP address belongs.

[0039] In some embodiments, the DHCP response message includes: a DHCP-ACK message and a DHCP-NAK message.

[0040] In a third aspect of the implementation of the present application, an electronic device is further provided, which is characterized by including a processor, a communication interface, a memory, and a communication bus. Among them, the processor, the communication interface, and the memory complete communication with each other through the communication bus;

[0041] The memory is used to store a computer program;

[0042] The processor is used to implement the information update method described in any one of the above when executing the program stored on the memory.

[0043] In yet another aspect of the implementation of the present invention, a computer-readable storage medium is further provided. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the information update method described in any one of the above is implemented.

[0044] Advantageous effects of the embodiments of the present invention:

[0045] The embodiments of the present application provide an information update method, which includes: sending a DHCP request message carrying an IP address to be verified to a DHCP server; where the IP address to be verified represents the IP address in any client information to be verified recorded; if within a first preset time period after sending the DHCP request message, a DHCP response message for the DHCP request message sent by the DHCP server is not received, then sending a reachability verification message to the DHCP server; if a reachability response message sent by the DHCP server is received within a second preset time period after sending the reachability verification message, then deleting the client information to be verified to which the IP address to be verified belongs.

[0046] Based on the above processing, if a reachability response message is received within the second preset time period after sending the reachability verification message, it indicates that the DHCP server is reachable, which also means that it is because the current IP address to be verified has been recycled by the DHCP server, that is, in an allocable state, resulting in not receiving a DHCP response message for the DHCP request message sent by the DHCP server within the first preset time period after sending the DHCP request message, rather than due to the unreachability of the DHCP server. Therefore, the client information to be verified to which the IP address to be verified belongs can be deleted, and thus the recorded client information can be effectively updated to ensure the security of the service.

[0047] Of course, it is not necessary for any product or method implementing the present invention to achieve all the above advantages simultaneously. Description of the Drawings

[0048] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other embodiments can also be obtained based on these drawings.

[0049] Figure 1 It is a schematic flowchart of an information update method provided by an embodiment of the present application;

[0050] Figure 2 It is a schematic flowchart of another information update method provided by an embodiment of the present application;

[0051] Figure 3 It is a schematic flowchart of yet another information update method provided by an embodiment of the present application;

[0052] Figure 4 It is a schematic flowchart of an information update provided by an embodiment of the present application;

[0053] Figure 5 It is a schematic structural diagram of an information update device provided by an embodiment of the present application;

[0054] Figure 6 It is a schematic structural diagram of an electronic device provided by an embodiment of the present application. Detailed implementation manners

[0055] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art based on the present application belong to the scope of protection of the present invention.

[0056] DHCP is a network protocol for a local area network. The DHCP network includes a DHCP server, a DHCP relay, and a DHCP client. For example, the DHCP server can be a server, or it can also be a switch, a router, etc.; the DHCP relay can be a switch.

[0057] The DHCP client can request the DHCP server to allocate a dynamic IP address through the DHCP relay. The DHCP relay can record the client information of the DHCP client, including information such as the IP address and MAC address of the DHCP client.

[0058] During the business processing, to improve the security of the business, the DHCP relay can verify the received packets according to the recorded client information and forward the packets that pass the verification. Since the IP addresses assigned by the DHCP server to the DHCP clients have a certain validity period, how to effectively update the recorded client information to ensure the security of the business has become an urgent problem to be solved.

[0059] To solve the above problems, the embodiments of the present application provide an information update method, which can be applied to the DHCP relay. Refer to Figure 1 , Figure 1 which is a schematic flow diagram of an information update method provided by the embodiments of the present application. The method may include the following steps:

[0060] S101: Send a DHCP request packet carrying the IP address to be verified to the DHCP server.

[0061] Wherein, the IP address to be verified represents the IP address in any of the recorded client information to be verified.

[0062] S102: If within the first preset time period after sending the DHCP request packet, a DHCP response packet for the DHCP request packet sent by the DHCP server is not received, send a reachability verification packet to the DHCP server.

[0063] S103: If within the second preset time period after sending the reachability verification packet, a reachability response packet sent by the DHCP server is received, delete the client information to be verified to which the IP address to be verified belongs.

[0064] Based on the above processing, if a reachability response packet is received within the second preset time period after sending the reachability verification packet, it indicates that the DHCP server is reachable, which also means that it is because the current IP address to be verified has been recycled by the DHCP server, that is, in an allocable state, resulting in not receiving the DHCP response packet for the DHCP request packet sent by the DHCP server within the first preset time period after sending the DHCP request packet, rather than due to the unreachability of the DHCP server. Therefore, the client information to be verified to which the IP address to be verified belongs can be deleted, and the recorded client information can be effectively updated to ensure the security of the business.

[0065] In the related art, the DHCP relay can send a DHCP-REQUEST (request) packet carrying the IP address to be verified to the DHCP server according to a preset period. For example, the preset period can be 1 minute or 30 seconds.

[0066] After the DHCP server receives a DHCP-REQUEST message, the DHCP server can determine whether the IP address to be verified is currently in an allocatable state.

[0067] If the IP address to be verified is in an unallocatable state, a DHCP-NAK (Negative Acknowledgment) message indicating that the IP address to be verified is currently in an unallocatable state can be sent to the DHCP relay. The DHCP-NAK message can also indicate that the IP address to be verified is currently within the validity period. Correspondingly, if the DHCP relay receives a DHCP-NAK message, the DHCP relay can retain the information of the client to be verified to which the IP address to be verified belongs.

[0068] If the IP address to be verified is in an unallocatable state and the DHCP server is a server, a DHCP-ACK (Acknowledgment) message indicating that the IP address to be verified is currently in an allocatable state can be sent to the DHCP relay. The DHCP-ACK message can also indicate that the IP address to be verified is not currently within the validity period. For example, the server may be configured with the Windows operating system. Correspondingly, if the DHCP relay receives a DHCP-ACK message, the DHCP relay will delete the information of the client to be verified to which the IP address to be verified belongs.

[0069] If the IP address to be verified is an IP address within the validity period and the DHCP server is a switch or a router, the DHCP server does not perform any operation, that is, it does not respond to the DHCP-REQUEST message. Correspondingly, if the DHCP relay does not receive a DHCP response message for the DHCP request message, the DHCP relay will delete the information of the client to be verified to which the IP address to be verified belongs.

[0070] It can be understood that when the DHCP server is unreachable, it will also cause the DHCP relay to be unable to receive the DHCP response message. For example, the DHCP server fails, or the connection between the DHCP relay and the DHCP server is disconnected. In the above cases, if the DHCP relay cannot receive the DHCP response message, it will delete the information of the client to be verified to which the IP address to be verified belongs, which will also cause the information of the client to be verified to which the IP address to be verified currently within the validity period belongs to be accidentally deleted, and further affect the normal use of the services provided by the DHCP network by the online clients.

[0071] It can be seen that, compared with the related art, the method provided by the embodiment of the present application can send a reachability verification message when the DHCP response message sent by the DHCP server is not received, so as to determine whether the DHCP server is reachable. Furthermore, it can avoid the situation of accidental deletion caused by the unreachability of the DHCP server in the related art and improve the stability of the service.

[0072] For step S101, during the process of the DHCP client requesting to allocate an IP address, the DHCP relay can record the client information of the DHCP client. For example, the client information may include: the MAC address of the DHCP client and the allocated IP address. For example, the DHCP relay can record the MAC address and IP address of the DHCP client in the form of a table, and this table can be called a dynamic user address table. In addition, for each recorded IP address, the DHCP relay can also record the identifier of the DHCP server that allocated this IP address. Subsequently, when it is necessary to verify this IP address, a DHCP request message can be sent to the DHCP server that allocated this IP address according to the recorded corresponding DHCP server identifier.

[0073] The client information to be verified is any client information recorded by the current DHCP relay.

[0074] For example, the DHCP relay can send a DHCP request message carrying the IP address to be verified to the DHCP server at a preset period. Among them, the DHCP request message can be expressed as a DHCP-REQUEST message.

[0075] The DHCP relay can communicate with at least one DHCP server and can also communicate with at least one DHCP client. The at least one DHCP server is used to allocate IP addresses to the at least one client. Correspondingly, when it is necessary to verify the IP address to be verified recorded by the DHCP relay, the DHCP relay can send a DHCP request message carrying the IP address to be verified to the at least one server. Subsequently, the processing is carried out based on steps S102 - S103. Specifically, it will be introduced in detail in the subsequent embodiments.

[0076] For step S102, the first preset duration can be determined by the technician according to the current scenario. For example, the first preset duration can be 1 second or 2 seconds.

[0077] If the DHCP relay communicates with only one DHCP server, that is, the DHCP server is responsible for IP address allocation and IP address verification. Correspondingly, the DHCP relay only sends a DHCP request message carrying the IP address to be verified to the DHCP server. If the DHCP relay does not receive a DHCP response message from the DHCP server for the above DHCP request message within the first preset time period after sending the DHCP request message, the DHCP relay may send a reachability verification message to the DHCP server.

[0078] If the DHCP relay communicates with multiple DHCP servers, that is, the multiple DHCP servers are jointly responsible for IP address allocation and IP address verification.

[0079] For example, if the IP addresses that the multiple DHCP servers can allocate are the same, that is, the IP resources between the DHCP servers are shared in this case, the DHCP relay can send a DHCP request message carrying the IP address to be verified to only one of the DHCP servers to verify the IP address to be verified; or, the DHCP relay can also send a DHCP request message carrying the IP address to be verified to all DHCP servers to verify the IP address to be verified.

[0080] For another example, if the IP addresses that the multiple DHCP servers can allocate are different, that is, each DHCP server is responsible for allocating a part of the IP addresses, and the IP resources between the DHCP servers are not shared in this case. Correspondingly, the DHCP relay can send a DHCP request message carrying the IP address to be verified to the DHCP server that allocates the IP address to be verified to verify the IP address to be verified.

[0081] The reachability verification message is used to detect whether the DHCP server is reachable. For example, the reachability verification message can be an ICMP-Ping (Internet Control Message Protocol-Packet Internet Groper) message.

[0082] For any DHCP server, when the DHCP server allocates an IP address to a DHCP client, it can also set and record the validity period corresponding to the IP address. At this time, the IP address is in an unallocable state. When the validity period arrives, the DHCP server can recycle the IP address and delete the validity period corresponding to the IP address. At this time, the IP address is in an allocable state. Correspondingly, that is, the DHCP server can determine the IP addresses that are currently in an allocable state and the IP addresses that are in an unallocable state.

[0083] When the DHCP server receives the DHCP request message sent by the DHCP relay, it can verify the IP address to be verified carried in the DHCP request message according to the currently allocable IP addresses and the non-allocable IP addresses, that is, determine whether the IP address to be verified is currently in an allocable state and perform corresponding operations.

[0084] In some embodiments, the method further includes:

[0085] If, within the first preset duration after sending the DHCP request message, the DHCP relay receives the DHCP-ACK message for the DHCP request message sent by the DHCP server, the DHCP relay deletes the information of the client to be verified to which the IP address to be verified belongs.

[0086] If the DHCP server is a server and the DHCP server determines that the IP address to be verified is not currently within the valid period, that is, the IP address to be verified is in an allocable state, the DHCP server can send a DHCP-ACK message indicating that the IP address to be verified is not currently within the valid period to the DHCP relay. Subsequently, when the DHCP relay receives the DHCP-ACK message sent by the DHCP server within the first preset duration after sending the DHCP request message, the DHCP relay deletes the information of the client to be verified to which the IP address to be verified belongs.

[0087] Based on the above processing, for the scenario where the DHCP server is a server, the DHCP relay can also effectively update the recorded information of the clients to be verified, ensure the security of the service, and further improve the applicable scope of the information update method and the robustness of the information update.

[0088] For step S103, the second preset duration can be determined by a technician according to the current scenario. For example, the second preset duration can be 1 second or 2 seconds.

[0089] For each DHCP server, the DHCP relay can send a reachability verification message to the DHCP server. If the DHCP relay receives the reachability response message sent by the DHCP server within the second preset duration after sending the reachability verification message, it indicates that the DHCP server is reachable.

[0090] For example, if the IP resources among DHCP servers are shared. In this case, if the DHCP relay receives a reachability response message sent by any DHCP server, it can be determined that within the first preset duration after the DHCP relay sends a DHCP request message, the reason for not receiving a DHCP response message from the DHCP server for the DHCP request message is that the IP address to be verified is in an allocatable state. At this time, the DHCP relay can delete the information of the client to be verified to which the IP address to be verified belongs.

[0091] For example, if the IP resources among DHCP servers are not shared. In this case, if the DHCP relay receives a reachability response message sent by the DHCP server that allocates the IP address to be verified, it can be determined that within the first preset duration after the DHCP relay sends a DHCP request message, the reason for not receiving a DHCP response message from the DHCP server for the DHCP request message is that the IP address to be verified is in an allocatable state. At this time, the DHCP relay can delete the information of the client to be verified to which the IP address to be verified belongs.

[0092] For the situation where the DHCP relay does not receive a reachability response message sent by the DHCP server within the second preset duration after sending the reachability verification message, the DHCP relay can handle it in any of the following at least ways:

[0093] Method 1:

[0094] As Figure 2 shown, Figure 2 is a schematic flowchart of another information update method provided by an embodiment of this application. On the basis of Figure 1 , this method further includes:

[0095] S104: If the DHCP relay does not receive a reachability response message sent by the DHCP server within the second preset duration after sending the reachability verification message, return to execute step S101 until the preset stop moment is reached, and delete the information of the client to be verified to which the IP address to be verified belongs.

[0096] Among them, the preset stop moment means: the moment obtained by extending the moment of the first sending of the reachability verification message by the preset retention duration corresponding to the information of the client to be verified.

[0097] For any DHCP server, if the DHCP relay does not receive the reachability response message sent by the DHCP server within the second preset duration after sending the reachability verification message to the DHCP server, it indicates that the DHCP relay may not receive the DHCP response message within the first preset duration after sending the DHCP request message because the current DHCP server is unreachable. That is, it cannot effectively determine whether the IP address to be verified is in an allocable state, nor can it effectively determine whether the client information to be verified belonging to the IP address to be verified needs to be deleted. Therefore, the client information to be verified belonging to the IP address to be verified can be retained for a certain duration, and step S101 can be returned for execution to continue verifying the IP address to be verified. Furthermore, it is possible to verify the IP address to be verified when the DHCP server is reachable, thus ensuring the timeliness of verification and the accuracy of the verification result.

[0098] Among them, the preset retention durations corresponding to different client information to be verified can be different or the same. For example, the preset retention duration can be 24 hours or 12 hours.

[0099] Based on the above processing, when the DHCP server corresponding to the IP address to be verified is unreachable, the DHCP relay can retain the client information to be verified belonging to the IP address to be verified based on the preset retention duration. This can avoid the client information to be verified belonging to the IP address to be verified that is currently within the valid period being mistakenly deleted due to communication problems in the DHCP network, thereby affecting the legitimate DHCP client's normal use of the services provided by the DHCP network.

[0100] For example, for an IP address, the corresponding preset retention duration can be not less than the duration of the valid period of the IP address. Correspondingly, if the DHCP server is still unreachable when the preset stop time is reached, it indicates that the valid period corresponding to the IP address to be verified has also ended, that is, the DHCP server has reclaimed the IP address. Furthermore, the DHCP relay can delete the client information to be verified belonging to the IP address to be verified to ensure the security of the DHCP network.

[0101] Method 2:

[0102] As Figure 3 shown, Figure 3 is a schematic flowchart of another information update method provided by an embodiment of the present application. On the basis of Figure 1 , this method further includes:

[0103] S105: If a reachability response message sent by the DHCP server is not received within the second preset duration after the reachability verification message is sent, determine whether there is client information of the to-be-verified client to which the to-be-verified IP address belongs in the client information of the recorded online clients.

[0104] If there is no client information of the to-be-verified client to which the to-be-verified IP address belongs in the client information of the recorded online clients, step S106 is executed.

[0105] S106: Delete the client information of the to-be-verified client to which the to-be-verified IP address belongs.

[0106] The DHCP relay can record the client information of online clients. For example, the client information of an online client may include: the MAC address and IP address of a DHCP client in the online state. For example, the DHCP relay can record the MAC address and IP address of a DHCP client in the online state in the form of a table, and this table can be called an ARP (Address Resolution Protocol) table. Specifically, the process of the DHCP relay updating the recorded client information of online clients will be introduced in detail in the subsequent embodiments.

[0107] For example, if the DHCP relay determines that the to-be-verified IP address does not exist in the IP addresses (which can be called online IP addresses) in the client information of the recorded online clients, it can be determined that there is no client information of the to-be-verified client to which the to-be-verified IP address belongs in the client information of the recorded online clients.

[0108] For example, after the DHCP server assigns an IP address to a certain DHCP client (which can be called DHCP client A), the DHCP relay can correspondingly record this IP address and the MAC address of DHCP client A. Subsequently, if this IP address (i.e., the to-be-verified IP address) is stolen by another client (which can be called DHCP client B), since the MAC address of DHCP client A is different from the MAC address of DHCP client B, therefore, it will also cause a situation where the to-be-verified IP address exists in the online IP addresses, and the MAC address corresponding to the to-be-verified IP address in the client information of the online clients is inconsistent with the MAC address in the client information of the client to which the to-be-verified IP address belongs. In view of the above situation, if the DHCP relay determines that the to-be-verified IP address exists in the online IP addresses, and the MAC address corresponding to the to-be-verified IP address in the client information of the online clients is inconsistent with the MAC address in the client information of the client to which the to-be-verified IP address belongs, it can be determined that there is no client information of the to-be-verified client to which the to-be-verified IP address belongs in the client information of the recorded online clients.

[0109] It can be understood that in the above two cases, the DHCP relay can determine that the DHCP client corresponding to the IP address to be verified is currently offline. It can be understood that the DHCP client is currently offline, that is, the DHCP client currently does not need to obtain services provided by the DHCP network based on the IP address to be verified. Accordingly, the DHCP relay can delete the information of the client to be verified to which the IP address to be verified belongs.

[0110] Based on the above processing, the DHCP relay can verify the information of the client to be verified to which the IP address to be verified belongs based on the recorded IP address and MAC address of the online client. It can prevent the IP address assigned by the DHCP server from being stolen by other clients and further ensure the security of the service.

[0111] In some embodiments, based on Method 2, the method further includes:

[0112] Step 1: If among the client information of the recorded online clients, there is information of the client to be verified to which the IP address to be verified belongs, then return to execute Step S101.

[0113] For example, if the DHCP relay determines that there is an online IP address in the recorded online IP addresses that is the same as the IP address to be verified, then it can be determined that among the client information of the recorded online clients, there is information of the client to be verified to which the IP address to be verified belongs.

[0114] Or, if the DHCP relay determines that there is an online IP address in the recorded online IP addresses that is the same as the IP address to be verified, and the MAC address corresponding to this online IP address is the same as the MAC address in the client information to which the IP address to be verified belongs, then it can be determined that among the client information of the recorded online clients, there is information of the client to be verified to which the IP address to be verified belongs.

[0115] It can be understood that after the online client receives the IP address assigned by the DHCP server for the first time, within the validity period corresponding to this IP address, it can apply to the DHCP server to continue using this IP address, that is, continuously update the validity period corresponding to this IP address. Since the DHCP server is unreachable at this time, that is, it is because the DHCP server is unreachable that the validity period corresponding to this IP address cannot be updated, and the DHCP client corresponding to this IP address has been pre-verified by the DHCP server, therefore, the DHCP relay can retain the information of the client to be verified to which the IP address to be verified belongs and return to execute Step S101.

[0116] The DHCP client corresponding to the IP address to be verified is currently online, that is, the DHCP client currently needs to obtain services provided by the DHCP network based on the IP address to be verified. Correspondingly, the DHCP relay can retain the client information of the client to be verified to which the IP address to be verified belongs, and return to execute steps S101 - S103 to process the client information of the client to be verified to which the IP address to be verified belongs. Based on the above processing, in the case of a DHCP server that cannot communicate with the DHCP relay normally, the DHCP relay retains the client information of the client to be verified to which the IP address to be verified belongs based on the client information of the recorded online clients, so that the online client can obtain the services provided by the DHCP network and ensure the stability of the services.

[0117] In one implementation, the DHCP relay updates the client information of the recorded online clients based on the Address Resolution Protocol (ARP) packets.

[0118] For example, for any DHCP client, the DHCP relay can record the client information of the DHCP client and the timestamp when the ARP packet sent by the DHCP client was received last time.

[0119] If no ARP packet sent by the DHCP client is received within the third preset duration extending backward from the recorded timestamp, an ARP request packet is sent to the DHCP client. If the DHCP relay does not receive an ARP response packet for the ARP request packet, it means that the DHCP client is not in the online state, and the client information of the online client corresponding to the DHCP client is deleted; if the DHCP relay receives an ARP response packet for the ARP request packet, it means that the DHCP client is in the online state, the client information of the online client corresponding to the DHCP client is retained, and the timestamp when the ARP response packet is received is recorded.

[0120] Based on the above processing, the DHCP relay can record and update the client information of the currently online clients, so that the online clients can obtain the services provided by the DHCP network and ensure the stability of the services.

[0121] In some embodiments, the method further includes:

[0122] Step 1: If no reachability response packet sent by the DHCP server is received within the second preset duration after sending the reachability verification packet, and there is a preset retention duration corresponding to the client information to be verified, return to execute step S101 until the preset stop time is reached, and then delete the client information to which the IP address to be verified belongs.

[0123] Among them, the preset stop time indicates: the time obtained by extending the time when the reachability verification message is first sent by the preset retention duration corresponding to the client information to be verified.

[0124] Step 2: If, within the second preset duration after sending the reachability verification message, a reachability response message sent by the DHCP server is not received and there is currently no preset retention duration corresponding to the client information to be verified, determine whether there is client information corresponding to the client to be verified to which the IP address to be verified belongs among the client information of the recorded online clients; if not, delete the client information corresponding to the IP address to be verified.

[0125] In the embodiments of the present application, technicians can pre-determine, according to service requirements, that the DHCP relay processes the client information corresponding to the IP address to be verified in different ways.

[0126] Within the second preset duration after sending the reachability verification message, a reachability response message sent by the DHCP server is not received. If there is currently a preset retention duration corresponding to the client information to be verified, it indicates that the DHCP relay can process the client information corresponding to the IP address to be verified based on the above-mentioned method 1; if there is currently no preset retention duration corresponding to the client information to be verified, it indicates that the DHCP relay can process the client information corresponding to the IP address to be verified based on the above-mentioned method 2, and thus can be applicable to different scenarios.

[0127] For example, technicians can send an enabling instruction for method 1 to the relay and set the corresponding preset retention duration. Then, the relay can process the client information corresponding to the IP address to be verified based on the above-mentioned method 1; subsequently, technicians can also send an enabling instruction for method 2, and then the relay can process the client information corresponding to the IP address to be verified based on the above-mentioned method 2. It can be understood that at the same moment, the DHCP relay can only process according to method 1 or method 2. Therefore, the enabling instruction for method 2 can also be understood as a disabling instruction for method 1.

[0128] That is, the process of processing the client information corresponding to the IP address to be verified based on step 1 can refer to the above-mentioned method 1; the process of processing the client information corresponding to the IP address to be verified based on step 2 can refer to the above-mentioned method 2.

[0129] In some embodiments, the DHCP response message includes: a DHCP-ACK message and a DHCP-NAK message.

[0130] For example, if the DHCP server is a switch or a router, and the DHCP server determines that the IP address to be verified is currently within the valid period, that is, the IP address to be verified is in an unassignable state, the DHCP server may send a DHCP-NAK message indicating that the IP address to be verified is currently within the valid period to the DHCP relay. Subsequently, when the DHCP relay receives the DHCP-NAK message sent by the DHCP server within the first preset duration after sending the DHCP request message, the DHCP relay retains the information of the client to be verified to which the IP address to be verified belongs.

[0131] If the DHCP server is a switch or a router, and the DHCP server determines that the IP address to be verified is not currently within the valid period, that is, the IP address to be verified is in an assignable state, the DHCP server may not perform any operation. Correspondingly, the DHCP relay cannot receive a DHCP response message within the first preset duration after sending the DHCP request message. Subsequently, the DHCP relay may execute step S103.

[0132] It can be understood that if the DHCP server is a switch or a router and the DHCP server is unreachable, it will still cause the DHCP relay to be unable to receive a DHCP response message within the first preset duration after sending the DHCP request message.

[0133] Therefore, in order to determine whether the IP address to be verified is in an assignable state, the DHCP relay may send a reachability verification message to the DHCP server.

[0134] Based on the above processing, for the scenario where the DHCP server is a switch or a router, the method provided in the embodiments of this application can send a reachability verification message when a DHCP response message sent by the DHCP server is not received, so as to determine whether the DHCP server is reachable. Furthermore, it can avoid the situation of incorrect deletion caused by the unreachability of the DHCP server and improve the stability of the service.

[0135] If the DHCP server is a server, and the DHCP server determines that the IP address to be verified is not currently within the valid period, that is, the IP address to be verified is in an assignable state, the DHCP server may send a DHCP-ACK message indicating that the IP address to be verified is not currently within the valid period to the DHCP relay. Subsequently, when the DHCP relay receives the DHCP-ACK message sent by the DHCP server within the first preset duration after sending the DHCP request message, the DHCP relay deletes the information of the client to be verified to which the IP address to be verified belongs.

[0136] If the DHCP server is a server and the DHCP server determines that the IP address to be verified is currently within the valid period, that is, the IP address to be verified is in an unassignable state, the DHCP server may send a DHCP-NAK message indicating that the IP address to be verified is currently within the valid period to the DHCP relay. Subsequently, when the DHCP relay receives the DHCP-NAK message sent by the DHCP server within the first preset duration after sending the DHCP request message, the DHCP relay retains the information of the client to be verified to which the IP address to be verified belongs.

[0137] It can be understood that if the DHCP server is a server and the DHCP server is unreachable, it will still cause the DHCP relay not to receive the DHCP response message for the DHCP request message sent by the DHCP server within the first preset duration after sending the DHCP request message.

[0138] It can be understood that in the case where the DHCP server is a server, if the DHCP-ACK message and the DHCP-NAK message are not received within the first preset duration after sending the DHCP request message, the processing can be performed based on step S103 above. Subsequently, the IP address to be verified is verified based on the above method 1 or method 2, and thus, the recorded client information can be effectively updated to ensure the security of the service.

[0139] See Figure 4 , Figure 4 which is a schematic diagram of a process for information update provided by an embodiment of the present application. Figure 4 includes the following steps:

[0140] S401: The user enables the DHCP relay dynamic user address entry timing refresh function.

[0141] That is, the DHCP relay dynamic user address entry timing refresh function is enabled, so that the DHCP relay can send a DHCP request message carrying the IP address to be verified to the DHCP server at a certain period.

[0142] S402: Determine whether a reply is received within a specified duration after the DHCP relay sends the DHCP request message. If yes, execute step S403; if not, execute step S404.

[0143] That is, determine whether a DHCP response message for the DHCP request message sent by the DHCP server is received within the first preset duration after sending the DHCP request message.

[0144] S403: Process the entries recorded by the DHCP relay according to the DHCP response message replied by the DHCP server.

[0145] That is, if the DHCP relay receives a DHCP response message (i.e., a DHCP-ACK message) from the DHCP server for the DHCP request message, it can delete the information of the client to be verified to which the IP address to be verified belongs; if the DHCP relay receives a DHCP response message (i.e., a DHCP-NAK message) from the DHCP server for the DHCP request message, it can retain the information of the client to be verified to which the IP address to be verified belongs.

[0146] S404: Send a Ping message to determine whether the DHCP server is reachable. If so, execute step S407; if not, execute step S405 or S406.

[0147] That is, send a reachability verification message to the DHCP server. If a reachability response message sent by the DHCP server is received within the second preset duration after sending the reachability verification message, execute step S407.

[0148] If a reachability response message sent by the DHCP server is not received within the second preset duration after sending the reachability verification message, execute step S405 or S406.

[0149] S405: A preset retention duration for the DHCP relay is configured. Determine whether the configured retention time has been reached. If so, execute step S407; if not, return to execute step S401.

[0150] That is, if there is a preset retention duration corresponding to the information of the client to be verified currently, it indicates that the DHCP relay can process the information of the client to be verified to which the IP address to be verified belongs based on the above method 1.

[0151] Specifically, if a reachability response message sent by the DHCP server is not received within the second preset duration after sending the reachability verification message, return to execute step S401 until the preset stop moment is reached, and delete the information of the client to be verified to which the IP address to be verified belongs.

[0152] S406: The preset retention duration for the DHCP relay is not configured. Check whether there is a consistent ARP entry according to the IP and MAC recorded by the DHCP relay. If not, execute step S407; if so, return to execute step S401.

[0153] That is, if there is no preset retention duration corresponding to the information of the client to be verified currently, it indicates that the DHCP relay can process the information of the client to be verified to which the IP address to be verified belongs based on the above method 2.

[0154] Specifically, if the reachability response message sent by the DHCP server is not received within the second preset duration after the reachability verification message is sent, it is determined whether there is the information of the client to be verified to which the IP address to be verified belongs in the client information of the recorded online clients. If it exists, return to execute step S401. If it does not exist, delete the information of the client to be verified to which the IP address to be verified belongs.

[0155] S407: Delete the DHCP relay record entry.

[0156] That is, delete the information of the client to be verified to which the IP address to be verified belongs.

[0157] The embodiment of the present application further provides an information update device. Refer to Figure 5 , Figure 5 which is a schematic structural diagram of an information update device provided by the embodiment of the present application. The device includes:

[0158] The first message sending module 501 is configured to send a DHCP request message carrying the IP address to be verified to the DHCP server; wherein, the IP address to be verified represents the IP address in any information of the client to be verified recorded.

[0159] The second message sending module 502 is configured to send a reachability verification message to the DHCP server if the DHCP response message for the DHCP request message sent by the DHCP server is not received within the first preset duration after the DHCP request message is sent.

[0160] The first deletion module 503 is configured to delete the information of the client to be verified to which the IP address to be verified belongs if the reachability response message sent by the DHCP server is received within the second preset duration after the reachability verification message is sent.

[0161] In some embodiments, the device further includes:

[0162] The first processing module is configured to trigger the first message sending module 501 until the preset stop moment if the reachability response message sent by the DHCP server is not received within the second preset duration after the reachability verification message is sent, and delete the information of the client to be verified to which the IP address to be verified belongs; wherein, the preset stop moment means: the moment obtained by extending the moment of the first sending of the reachability verification message by the preset retention duration corresponding to the information of the client to be verified.

[0163] In some embodiments, the device further includes:

[0164] An online judgment module, configured to, if within a second preset time period after sending the reachability verification message, the reachability response message sent by the DHCP server is not received, judge whether the client information of the to-be-verified client to which the to-be-verified IP address belongs exists in the client information of the recorded online clients;

[0165] A second processing module, configured to, if the client information of the to-be-verified client to which the to-be-verified IP address belongs does not exist in the client information of the recorded online clients, delete the client information of the to-be-verified client to which the to-be-verified IP address belongs.

[0166] In some embodiments, the device further includes:

[0167] A third processing module, configured to, if the client information of the to-be-verified client to which the to-be-verified IP address belongs exists in the client information of the recorded online clients, trigger the first message sending module 501.

[0168] In some embodiments, the device further includes:

[0169] A fourth processing module, configured to, if within a second preset time period after sending the reachability verification message, the reachability response message sent by the DHCP server is not received, and there is a preset retention period corresponding to the to-be-verified client information currently, trigger the first message sending module 501 until a preset stop time is reached, and then delete the client information of the to-be-verified client to which the to-be-verified IP address belongs; wherein, the preset stop time means: the time obtained by extending the time corresponding to the preset retention period corresponding to the to-be-verified client information backward from the time when the first reachability verification message is sent;

[0170] A fifth processing module, configured to, if within a second preset time period after sending the reachability verification message, the reachability response message sent by the DHCP server is not received, and there is no preset retention period corresponding to the to-be-verified client information currently, judge whether the client information of the to-be-verified client to which the to-be-verified IP address belongs exists in the client information of the recorded online clients; if not, delete the client information of the to-be-verified client to which the to-be-verified IP address belongs.

[0171] In some embodiments, the device further includes:

[0172] A second deletion module, configured to, if within a first preset time period after sending the DHCP request message, the DHCP-ACK message for the DHCP request message sent by the DHCP server is received, delete the client information of the to-be-verified client to which the to-be-verified IP address belongs.

[0173] In some embodiments, the DHCP response message includes: a DHCP-ACK message and a DHCP-NAK message.

[0174] An embodiment of the present invention further provides an electronic device, such as Figure 6 shown, including a processor 601, a communication interface 602, a memory 603, and a communication bus 604. Among them, the processor 601, the communication interface 602, and the memory 603 communicate with each other through the communication bus 604.

[0175] The memory 603 is used to store a computer program.

[0176] When the processor 601 is used to execute the program stored on the memory 603, the information update method described in any one of the above is implemented.

[0177] The communication bus mentioned in the above electronic device may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus can be divided into an address bus, a data bus, a control bus, etc. For the sake of simplicity, only a thick line is used in the figure to represent it, but it does not mean that there is only one bus or one type of bus.

[0178] The communication interface is used for communication between the above electronic device and other devices.

[0179] The memory may include a Random Access Memory (RAM), or may also include a Non-Volatile Memory (NVM), such as at least one disk memory. Optionally, the memory may also be at least one storage device located far from the aforementioned processor.

[0180] The above-mentioned processor may be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0181] In another embodiment provided by the present invention, there is also provided a computer-readable storage medium storing a computer program, and when the computer program is executed by a processor, the steps of any of the above information update methods are implemented.

[0182] In another embodiment provided by the present invention, there is also provided a computer program product containing instructions, and when it runs on a computer, the computer is enabled to execute any of the information update methods in the above embodiments.

[0183] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present invention are generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another. For example, the computer instructions may be transmitted from a website, computer, server, or data center to another website, computer, server, or data center by wire (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.). The computer-readable storage medium may be any available medium that can be accessed by a computer or a data storage device such as a server or data center integrating one or more available media. The available medium may be a magnetic medium (such as a floppy disk, hard disk, magnetic tape), an optical medium (such as a DVD), or a semiconductor medium (such as a solid state disk (SSD)).

[0184] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including", or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article, or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article, or device. Without further limitation, an element defined by the statement "including a..." does not exclude the existence of additional identical elements in the process, method, article, or device including the element.

[0185] Each embodiment in this specification is described in a related manner. For the same or similar parts among the embodiments, reference can be made to each other. Each embodiment focuses on the differences from other embodiments. In particular, for the embodiments of the device, electronic device, computer-readable storage medium, and computer program product, since they are basically similar to the method embodiments, the description is relatively simple, and reference can be made to the corresponding parts of the method embodiments for the relevant content.

[0186] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are all included in the protection scope of the present invention.

Claims

1. An information update method, characterized in that, The method includes: Sending a DHCP request message carrying an IP address to be verified to a Dynamic Host Configuration Protocol (DHCP) server; wherein, the IP address to be verified represents the IP address in any client information to be verified recorded. If a DHCP response message for the DHCP request message is not received from the DHCP server within a first preset time period after sending the DHCP request message, sending a reachability verification message to the DHCP server. If a reachability response message sent by the DHCP server is received within a second preset time period after sending the reachability verification message, deleting the client information to be verified to which the IP address to be verified belongs. If a reachability response message sent by the DHCP server is not received within a second preset time period after sending the reachability verification message, returning to execute the step of sending a DHCP request message carrying the IP address to be verified to the DHCP server until a preset stop time is reached, and deleting the client information to be verified to which the IP address to be verified belongs; wherein, the preset stop time represents: the time corresponding to the preset retention duration corresponding to the client information to be verified extended backward from the time when the reachability verification message is sent for the first time.

2. The method according to claim 1, characterized in that, The method further includes: If a reachability response message sent by the DHCP server is not received within a second preset time period after sending the reachability verification message, determining whether the client information to be verified to which the IP address to be verified belongs exists in the client information of the recorded online clients. If the client information to be verified to which the IP address to be verified belongs does not exist in the client information of the recorded online clients, deleting the client information to be verified to which the IP address to be verified belongs.

3. The method according to claim 2, characterized in that, The method further includes: If the client information to be verified to which the IP address to be verified belongs exists in the client information of the recorded online clients, returning to execute the step of sending a DHCP request message carrying the IP address to be verified to the DHCP server.

4. The method according to claim 1, characterized in that, The method further includes: If a reachability response message sent by the DHCP server is not received within a second preset time period after sending the reachability verification message, and there is currently no preset retention duration corresponding to the client information to be verified, determining whether the client information to be verified to which the IP address to be verified belongs exists in the client information of the recorded online clients; if not, deleting the client information to be verified to which the IP address to be verified belongs.

5. The method according to claim 1, characterized in that, The method further includes: If a DHCP-ACK message for the DHCP request message is received from the DHCP server within a first preset time period after sending the DHCP request message, deleting the client information to be verified to which the IP address to be verified belongs.

6. The method according to claim 1, characterized in that, The DHCP response message includes: a DHCP-ACK message and a DHCP-NAK message.

7. An information update device, characterized in that, The device includes: A first message sending module, configured to send a DHCP request message carrying an IP address to be verified to a Dynamic Host Configuration Protocol (DHCP) server; wherein, the IP address to be verified represents the IP address in any client information to be verified recorded. A second message sending module, configured to, if within a first preset time period after sending the DHCP request message, a DHCP response message for the DHCP request message sent by the DHCP server is not received, send a reachability verification message to the DHCP server. A first deletion module, configured to, if within a second preset time period after sending the reachability verification message, a reachability response message sent by the DHCP server is received, delete the client information to be verified to which the IP address to be verified belongs. The apparatus further includes: a first processing module, configured to, if within a second preset time period after sending the reachability verification message, a reachability response message sent by the DHCP server is not received, trigger the first message sending module until a preset stop time is reached, and then delete the client information to be verified to which the IP address to be verified belongs; wherein, the preset stop time represents: the time corresponding to the preset retention duration corresponding to the client information to be verified extended backward from the time when the reachability verification message is first sent.

8. The device according to claim 7, characterized in that, The apparatus further includes: An online judgment module, configured to, if within a second preset time period after sending the reachability verification message, a reachability response message sent by the DHCP server is not received, judge whether the client information of the online clients recorded contains the client information to be verified to which the IP address to be verified belongs. A second processing module, configured to, if the client information of the online clients recorded does not contain the client information to be verified to which the IP address to be verified belongs, delete the client information to be verified to which the IP address to be verified belongs.

9. The device according to claim 8, characterized in that, The apparatus further includes: A third processing module, configured to, if the client information of the online clients recorded contains the client information to be verified to which the IP address to be verified belongs, trigger the first message sending module.

10. The device according to claim 7, characterized in that, The apparatus further includes: A fifth processing module, configured to, if within a second preset time period after sending the reachability verification message, a reachability response message sent by the DHCP server is not received and there is currently no preset retention duration corresponding to the client information to be verified, judge whether the client information of the online clients recorded contains the client information to be verified to which the IP address to be verified belongs; if not, delete the client information to be verified to which the IP address to be verified belongs.

11. The device according to claim 7, characterized in that, The apparatus further includes: A second deletion module, configured to, if within a first preset time period after sending the DHCP request message, a DHCP-ACK message for the DHCP request message sent by the DHCP server is received, delete the client information to be verified to which the IP address to be verified belongs.

12. The device according to claim 7, wherein The DHCP response message includes: a DHCP-ACK message and a DHCP-NAK message.

13. An electronic device, characterized in that It includes a processor, a communication interface, a memory, and a communication bus. Among them, the processor, the communication interface, and the memory complete their mutual communication through the communication bus; The memory is used to store computer programs; The processor is used to implement the method steps described in any one of claims 1-6 when executing the programs stored on the memory.

14. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer programs, and when the computer programs are executed by the processor, the method steps described in any one of claims 1-6 are implemented.

Images