KR20050079589A - Apparatus and method of file transfer in file transfer system - Google Patents

Abstract

The present invention relates to a file transfer method and a device thereof of a file transfer system. Even when a plurality of client systems are connected to one server system and request file transfer at the same time, data of the requested file can be received without error in each client system. It is possible to transfer the data of the file in the 1: N transmission method by deviating from the 1: 1 transfer method of the conventional TFTP, thereby maximizing the transmission speed of the file data.

Description

File transfer method and apparatus thereof in file transfer system {apparatus and method of file transfer in File Transfer System}

The present invention relates to a file transfer method and apparatus thereof of a file transfer system. More particularly, the present invention relates to a file transfer method in which a plurality of client systems simultaneously request a file transfer to a server system to receive a file without error. The present invention relates to a file transfer method of a system and a device thereof.

Data on most systems is expressed in units called files, and data transfer between systems requires a file or part of a file.

In a networked system, when a user of one system wants to receive data from another system to his or her system or to transfer data from one system to another, that is, to communicate with each other. In the case, there must be rules and regulations to enable these systems to communicate, which is the protocol.

In this case, a system for requesting data transmission is called a client system, and a system for providing a service for such a request is called a server system. Usually, a plurality of client systems are connected to one server system.

The most widely used language in computer networks is TCP / IP (Transfer Control Protocol / Internet Protocol), which is based on TCP / IP and includes File Transfer Protocol (FTP), Terminal Emulation Protocol (Telnet), and Hyper text (HTTP). Transfer Protocol).

The purpose of the file transfer protocol (FTP) here is to transfer a file or part of a file from one system to another under the command of an FTP user.

Most of the time FTP is used interactively by online users. The communication of FTP users is mediated by the operating system, which has input / output (I / O) drivers.

If a user on system A wants to access a file on system B, FTP on A establishes a connection with FTP on B. This is, of course, a logical connection, with the actual path to control information and user data going through each layer of the protocol stack.

On the other hand, TFTP (Trivial File Transfer Protocol) is a type of FTP that is designed to be implemented with simpler and smaller code than FTP, which is easily implemented in read-only memory (ROM), and is commonly used as a protocol for downloading an operating system image on a diskless system. It is done.

In general, FTP is a protocol for sending / receiving files in a reliable, connection-oriented manner using TCP.

TFTP, on the other hand, is a connectionless file transfer protocol that uses UDP. It is mainly used when routers receive configuration files and IOS images, and it is faster than FTP because there is no security option.

If you look at the contents of TCP and UDP, you can see the difference between the two transmissions. As mentioned above, TCP is a connection-oriented reliable protocol that controls flow through a sliding window.

In addition, TCP is controlled by using the sequence number and acknowledgment number. TCP transmits all data that has not received acknowledgment and sends the next data only when a signal is received. To ensure reliability.

However, in UDP, there is no checksum that data arrives well like TCP. Therefore, the transmission speed is very fast. Since there is no connection, there is no need to transmit a control frame, thereby reducing the load on the network.

Instead, UDP has no confirmation procedure or flow control. Instead, the application program has to take over its role. This method is called unidirectional transmission.

The TFTP protocol described above was designed long ago for small file transfers, and is easier to implement than Internet FTP, has a server-client structure, uses IP / UDP, and the protocol is defined in 'IETF RFC1350'. It is.

This protocol has been widely used in many systems to date because of the ease of file transfer in small programs, and over 32 Mbytes due to the fixed transfer of 512 bytes of data and the limitation of 65535 blocks max size. Was not transferable.

In order to overcome these limitations, optional features were added later, and these functions became more usable by allowing the data transfer size to be adjusted. This content is standardized in RFC 2347 TFTP Option Extension, RFC 2348 Blocksize Option.

In addition, 'RFC2090' has a multicast option to enable multicast. However, 'RFC2090' is an experimental version, not standardized, and the server can be implemented but is not implemented in most clients.

Currently, TFTP server-client programs are provided by Berkeley Software Distribution (BSD), UNIX, and Linux series by default, and there are many programs that can be used as freeware in Windows.

This TFTP protocol is not used well in situations where network functions are well implemented, but it is very widely used when PCs or many systems (nearly all devices with network functions) need to first boot without a OS and download a package. .

The TFTP protocol basically allows a server and a client to operate in a 1: 1 manner, which is not suitable for multiple clients receiving files from one server.

In a PC clustering environment or when one device is composed of several modules and each module receives basic files from the main module at the moment of power on, when multiple clients attempt to transfer files to one server at the same time, all of the servers Attempting file transfer in a 1: 1 manner increases network load and increases file transfer errors.

In order to overcome this problem, multicast TFTP is defined in 'RFC2090', but it is not standardized in experimental state and is complicated to implement in client.

The multicast function defined in 'RFC2090' must have a multicast IP address to be used for transmission, and clients must have file block recombination on the client itself since other clients will receive from the middle of the file when connecting while receiving a file transfer. .

However, since the environment using TFTP is generally performed at the time of initial booting instead of the normal network function, the implementation programs of clients are designed to perform only the simplest operation.

Therefore, in most TFTP functions, the server program can be improved to have a complicated function. However, since the TFTP function as a client operates very simply, it is difficult to handle functions such as block recombination.

In this case, the TFTP client function exchanges data packets and ACK packets in order according to block #. If a packet is lost during transmission, the operation is blocked and the file transfer itself is stopped or restarted by a timer. .

Accordingly, the present invention was devised to solve the above problems, and a plurality of client systems are connected to one server system to request a file transfer, and a file reception error of the client that occurs while the server system transfers files at the same time. It is an object of the present invention to provide a file transfer method and a device of a file transfer system that prevents.

The file transfer system according to an aspect of the present invention for achieving the above object, transmits an extended read request message (RRQ) of a simple file transfer protocol (TFTP) including a multi-client option, the option acceptance response The unique number information allocated through the message (OACK) is checked, and when the extended read request message is received from the client system, and the unique number information allocated to the client system is received. And a server system for transmitting the file data including the option acknowledgment message included and the unique number information to be assigned.

The read request message according to the present invention supports an operating code field indicating a value for a message type, a file name field encoded with an ASCII code, a mode field defining a transmission mode, and a multi-client system. It includes an option field for doing, and a mask bit field for defining the value of the option field.

In addition, the option acceptance response message according to the present invention includes an operating code field indicating a value for a message type, a multi-client field for supporting a multi-client system, and a unique number for indicating unique number information assigned to the client system. Contains a field.

A file transfer method of a file transfer system according to another aspect of the present invention includes the steps of: transmitting, by a first client system, an extended read request message (RRQ) requesting multi-client file transfer to a server system; Assigning the unique number information to the client, transmitting an option acknowledgment message (OACK) including the unique number information, and a response message (ACK) containing the unique number information assigned to the server by the first client system. Transmitting the file data including the unique number information to the first client by the server system; and unique number information to which the unique number information included in the file data transmitted by the first client system through the network is assigned. Checking whether the same and if the same, and receiving the same.

In addition, in the file transfer method of the file transfer system according to the present invention, when a read request message (RRQ) requesting multi-client file transfer is received from the second client system, unique number information is assigned to the second client system. Transmitting an acknowledgment response message (OACK), acquiring the unique number information by the second client system, transmitting an acknowledgment message (ACK) including the unique number information, and the server system of the first client system. Transmitting the file data including the unique number information of the second client system while transmitting the file data including the unique number information, and the unique number information of the file data transmitted through the network by the second client system is If the same as the unique number information, further comprising the step of receiving file data.

In addition, the file transfer method of the file transfer system according to the present invention, if the server system does not support the multi-client option function, if an extended read request message for requesting the multi-client file transfer from any client system is transmitted, The system further includes the step of sending an error message to the client.

In addition, the file transfer method of the file transfer system according to the present invention, if the server system does not support the multi-client option function, if an extended read request message for requesting the multi-client file transfer from any client system is transmitted, The method may further include transmitting an option acknowledgment message (OACK) to the client by adding only a function that can be supported by the system.

Hereinafter, a file transfer method and a device thereof of a file transfer system according to the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram illustrating an entire configuration of a file transfer system applied to the present invention.

Referring to FIG. 1, the file transfer system applied to the present invention includes a server system 10 and a plurality of client systems 20a to 20n connected to a network 30.

Hereinafter, a file exchange between the server system 10 and one client system 20a in a general file transfer system (TFTP) will be described.

The server system 10 and the client system 20a are connected to each other via the network 30 to exchange files 40.

At this time, the file exchange between the TFTP client 24a of the client system 20a and the TFTP server 14 of the server system 10 selects UDP among TCP / UDP, and selects IP (Internet Protocol) 12, 22a. Is executed on the Ethernet 11a.

When the TFTP client 24a is connected to the server system 10 via the network 30, it initiates a connection to the TFTP server 14 to exchange files 40.

That is, the TFTP client 24a transmits a read / write request message (RRQ: Read ReQuest / WRQ: Write ReQuest) to the TFTP server 14 in order to exchange files with the TFTP server 14.

At this time, the TFTP client 24a selects a UDP port among the TCP / UDP 23a of the client system 20a, and reads / writes a request message (RRQ /) including its IP address and the selected port number through the selected port. WRQ) to the TFTP server 14.

The TFTP server 14 receives a read / write request message (RRQ / WRQ) sent from the TFTP client 24a also through the UDP port of the TCP / UDP 13 of the server system 10.

When the read / write request message is received, the TFTP server 14 registers the IP address and port number of the TFTP client 24a, and uses the registered IP address and port number to read / write the request message. Sends a response message (ACK) to the TFTP client 24a.

The TFTP client 24a receives the response message (ACK) transmitted by the TFTP server 14 through the UDP 23 port of the client system 20 that has transmitted the read / write request message, thereby providing the server system 10 with the server system 10. A connection for file exchange between client systems 20 is made.

When the TFTP server 14 and the TFTP client 24a are connected, the file 40 requested by the TFTP client 24a is transmitted through a read / write request message RRQ / WRQ.

The TFTP server 14 continues the connection between the TFTP server 14 and the TFTP client 24a until the transfer of the file 40 requested by the TFTP client 24a is completed, and the transfer is completed and the client system ( 20a) or closing the connection on the server system 10 side releases the connection between the TFTP server 14 and the TFTP client 24a.

On the other hand, in order to transfer files to the file transfer system to multiple clients, it is necessary to define new options and redefine the message format according to the protocol of RFC 2347.

In general, the read request message RRQ is a message used by the client system 20a to 20n to establish a connection for receiving the file 40 from the server system 10. The read request message RRQ is a request message for downloading the file 40. to be.

In this case, OPC (OPeration Code) value of the first field of the RRQ message is used with '1', 'Filename' is composed of a variable length character string, and is accompanied by a definition field for the transmission mode.

In addition, the write request message WRQ is a message used by the client systems 20a to 20n to establish a connection for transmitting a file to the server system 10 and is a request message for uploading a file. In this case, '2' is used as the OPC value of the first field of the WRQ message.

Meanwhile, '3' is used as an OPC value of a message for transmitting a data block, and '4' is used as an OPC value of an acknowledgment (ACK) message for receiving a data block.

When an error occurs, OPC value of error message is used as '5'. It is recommended to use '6' as OPC value of OACK (Option ACK) message when adding option to RRQ message and WRQ message in 'Extension TFTP'. Doing.

2A is a diagram illustrating an RRQ message structure according to a preferred embodiment of the present invention.

Referring to FIG. 2A, the RRQ message structure includes an operating code (OPC) field 31, a file name field 32, a mode field 34, an option field 36, and a mask bit. (Mask bit) field 38 is formed.

The value of the operating code of the operating code field 31 is '1', and the file name of the file name field 32 is encoded as an ASCII code in a variable-length character string, and is terminated by a one-byte field 33. Is displayed.

The mode field 34 is used to define the transmission mode. In the case of the ASCII mode, the string "netascii" is used. In the case of a binary file, the "octet" is used. Display.

Option field 36 is a newly defined field to support multiple client systems 20a-20n using "mclient" as the option string and indicates the endpoint by single byte field 37.

2B is a view for explaining the application of the actual number to the format of the RRQ message according to the present invention.

Referring to FIG. 2B, an operating code '1', a file name "foofile", a transfer mode "octet", and an option field "mclient" are defined.

That is, the RRQ message shown in FIG. 2B is an RRQ message that the client systems 20a to 20n request the file “foofile” to the server system 10 in an “octet” transmission method.

Meanwhile, the OACK message transmitted by the server system 10 in response to the RRQ message received from the client systems 20a to 20n will be described.

3A is a diagram illustrating a structure of an OACK response message transmitted by a server system used in the present invention.

Referring to FIG. 3A, an OACK message consists of an operating code (OPC) field 41, a multiple client field 42, a one byte field 43, a unique number field 44, and a one byte field 45.

The value of the operating code is '6' in the operating code field 41, the string "mclient" is defined in the multi-client field 42, and the end point is indicated by the one-byte field 43.

The unique number field 44 defines the values for the multiple client options, and unique number information of each client system 20a to 20n allocated by the server system 10 is defined.

That is, the TFTP server 14 of the server system 10 assigns a unique number in random numbers to the client systems 20a to 20n that transmitted the first RRQ message, and then uniquely to the clients 20a to 20n transmitting the RRQ message. Constantly increase the number to assign a unique number.

At this time, the TFTP server 14 may assign a unique number to each client (20a ~ 20n) in the table form as shown in Table 1.

Table 1 above describes a case in which the TFTP server 14 transmits the RRQ message from the first client system 20a and the RRQ message from the second client system 20b and the third client system 20c. ought.

In this case, when the unique number '33' is assigned to the first client system 20a, the TFTP server 14 may allocate the increased '34' and '35' to the next client systems 20b to 20n.

3B is a view for explaining the application of the actual number to the format of the OACK message according to the present invention.

Referring to FIG. 3B, the operating code may be defined as '6', the multiple client field is “mclient”, and the unique number field is “33”.

In this case, "33" defined in the unique number field is unique number information allocated to the client systems 20a to 20n by the server system 10.

4 is a diagram illustrating an ACK message transmitted by a client system according to the present invention.

4, an ACK message according to the present invention consists of an operating code field 51, a block number field 52 and a unique number field 53.

Here, the block number field 52 defines block number information for ensuring the sequence of the data of the file 40 requested by the client systems 20a to 20n, and the unique number field 53 indicates the corresponding client system 20a to. 20n) defines the unique number information assigned from the server system 10.

That is, each client system 20a to 20n grasps the unique number information allocated in the OACK message received from the server system 10, and identifies the unique number information assigned to the ACK message and the received file 40 data. In order to guarantee the sequence, the block number information is included and transmitted to inform the data of the file 40 of the received file.

The server system 10 checks the unique number information and the block number information included in the ACK message transmitted from the client systems 20a to 20n, and transmits the data of the file 40.

At this time, the value defined in the operation code field 41 is '4'.

5 is a view for explaining data transmitted by the server system according to the present invention.

Referring to FIG. 5, data according to the present invention is composed of an operation code field 61, a block number field 62, a unique number field 63, and a data field 64.

The block number field 62 defines the block number information of the file 40 transmitted by the server system 10, and the unique number field 63 defines the client system 20a to receive data of the file 40 to be transmitted. A unique number assigned to 20n) is defined, and the data field 64 defines the data content of the file 40 to be transmitted.

That is, the server system 10 checks the unique number information in the ACK message received from each client system 20a to 20n, checks the data of the file 40 to be transmitted to the client systems 20a to 20n, and blocks The number information is grasped and the data of the file 40 to be transmitted is transmitted.

At this time, the server system 10 transmits data corresponding to the next block number information of the identified block number information, and increases the block number information.

At this time, the value defined in the operation code field 41 is '2'.

6 is a flowchart illustrating a flow of a file transfer method according to an embodiment of the present invention.

Referring to FIG. 6, the first client system 20a transmits a read request (RRQ) message to download the file 40 from the server system 10. The newly defined option field includes an "mclient" option. The RRQ message is transmitted (S 100).

The first client system 20a transmits an RRQ message to the server system 10 to transmit the file 40 called "foofile" to the "octet" transmission method.

At this time, the first client system 20a defines “mclient” in the option field to receive the file 40 through the multi-client function, and transmits an RRQ message.

The server system 10 receives the original RRQ message and transmits an OACK message to the first client system 20a that accepts the "mclient" option (S 101).

At this time, the server system 10 grasps and registers IP address and UDP port information of the client systems 20a to 20n in the RRQ message, registers them, and assigns a unique number to the client systems 20a to 20n.

As an example, a case where '33' is assigned to the first client system 20a as a unique number will be described.

In addition, the server system 10 transmits an OACK message including unique number information allocated to the client systems 20a to 20n.

On the other hand, if the server system 10 does not support the multi-client option function, when the extended read request (RRQ) message requesting the multi-client file transfer from the client system (20a ~ 20n) is transmitted, the server system 10 The error message is transmitted to the corresponding client systems 20a to 20n, or only the function that the server system 10 can support is added to transmit the option acknowledgment message (OACK) to the client systems 20a to 20n.

When the OACK message is received from the server system 10, the first client system 20a grasps the unique number information allocated thereto from the OACK message, and the server system sends an ACK message including the identified unique number information. Transmit to 10 (S 102).

When the ACK message is transmitted from the first client system 20a, the server system 10 checks the unique number information of the corresponding client systems 20a to 20n included in the ACK message, and if the assigned unique number information is correct, The data of the file 40 is transmitted (S 103).

At this time, the TFTP server 14 of the server system 10 includes the block number information of the data of the transmitted file 40 in the block number field 62 and transmits it.

When the first client system 20a receives the data of the file 40 from the server system 10 via the network 30, the first client system 20a checks the unique number information of the data, and if it is the same as the unique number information assigned to itself, Receive data.

The first client system 20a checks the block number information included in the received data, and transmits an ACK message including the checked block number information to the server system 10 (S 104).

Meanwhile, when the second client system 20b is connected to the server system 10 through the network 30, and transmits an RRQ message to the server system 10 to receive a file through the multi-client file transfer function (S 105). The server system 10 checks and registers the IP address and the port number of the second client system 20b, and assigns a unique number.

In this case, since the unique number '33' is assigned to the first client system 20a, the second client system 20b may be assigned a unique number by incrementing '1' from the allocated '33'.

Then, the server system 10 transmits an OACK message including the assigned unique number to the second client system 20b (S 106).

In addition, the server system 10 transmits data of the file 40 to be transmitted to the first client system 20a, including block number information and a unique number of the first client system 20a (S 107 and S 112). .

When the first client system 20a receives the data of the file 40 from the server system 10, the first client system 20a receives the block number information of the received data of the file 40 and an ACK message including the unique number assigned thereto. Is transmitted to the server system 10 (S 104, S 113).

In addition, the server system 10 transmits the data of the file 40 to be transmitted to the second client system 20b, including block number information and the unique number of the second client system 20b (S 110 and S 114). , S 116).

When the second client system 20b receives the data of the file 40 from the server system 10, the second client system 20b includes an ACK message including block number information of the received file 40 data and a unique number assigned thereto. Is transmitted to the server system (S 111, S 115, S 117).

Although described in detail with respect to preferred embodiments of the present invention, those skilled in the art to which the present invention pertains, the present invention without departing from the spirit and scope of the invention defined in the appended claims It will be appreciated that various modifications or changes can be made. Therefore, changes in the future embodiments of the present invention will not be able to escape the technology of the present invention.

As described above, according to the present invention, even when a plurality of client systems are connected to one server system to request file transfers at the same time, data of the requested file can be received without error.

In addition, by deviating from the 1: 1 transfer method of the conventional TFTP, the data of the file can be transmitted by the 1: N transmission method, thereby maximizing the transmission speed of the file data.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an overall block diagram illustrating the overall configuration of a file transfer system applied to the present invention.

2A illustrates an RRQ message structure in accordance with a preferred embodiment of the present invention.

FIG. 2B is a diagram illustrating the application of an actual number to the format of an RRQ message in accordance with the present invention. FIG.

3A is a diagram illustrating a structure of an OACK response message transmitted by a server system used in the present invention.

3B is a diagram for explaining the application of actual values to the format of an OACK message according to the present invention.

4 is a diagram illustrating an ACK message transmitted by a client system according to the present invention.

5 is a view for explaining data transmitted by the server system according to the present invention.

6 is a flowchart illustrating a flow of a file transfer method according to an embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

10: server system 14: TFTP server

20a ~ 20n: Client System 24a ~ 24n: TFTP Client

Claims (16)

In a file transfer system, Send an extended read request message (RRQ) of a simple file transfer protocol (TFTP) with multiple client options, check the unique number information assigned through an option acknowledgment message (OACK), and receive the file data. At least one client system; And If an extended read request message is received from the client system, the server system transmits an option acknowledgment message including the unique number information to be assigned to the client system and file data including the unique number information to be allocated. File transfer system. The method of claim 1, wherein the extended read request message, An operating code field indicating a value for a message type; A file name field encoded with an ASCII code file name; A mode field defining a transmission mode; An option field for supporting multiple client systems; And File transfer system including a mask bit field for defining the value of the option field. The method of claim 1, wherein the option acceptance message is: An operating code field indicating a value for a message type; Multiple client fields to support multiple client systems; And And a unique number field for indicating unique number information assigned to the client system. The method of claim 1, wherein the server system, And assigning random unique number information to the client system that transmitted the first read request message, and incrementing the unique number information to the client system transmitting the next read request message and allocating the unique number information to the corresponding client system. The method of claim 1, wherein the server system, And transmitting file data including block number information and unique number information of the file data in order to ensure the sequence of the file data. The system of claim 1, wherein each client system comprises: The block number information and the unique number information included in the file data transmitted from the server system are identified. If the unique number information is the same as the unique number information allocated through the option acknowledgment response message, the file data is received. And transmitting a response message (ACK) including the block number information to the server system. The method of claim 1, wherein the server system, If the multi-client optional feature is not supported, and an extended read request message is sent from any client system requesting a multi-client file transfer, the server system can only send an error message to that client or add support for it. A file transfer system comprising transmitting an option acknowledgment message (OACK) to a client. In the file transfer method of the file transfer system, Sending, by the first client system, an extended read request message (RRQ) requesting multiple client file transfers to the server system; The server system assigning unique number information to the first client and transmitting an option acknowledgment message (OACK) including the unique number information; Transmitting, by the first client system, an acknowledgment message (ACK) containing unique number information allocated to the server; Transmitting, by the server system, file data including unique number information to the first client; And checking, by the first client system, whether the unique number information included in the file data transmitted through the network is the same as the assigned unique number information and receiving the same if the same. The method of claim 8, If a read request message (RRQ) is received from the second client system requesting multi-client file transfer, assigning unique number information to the second client system, and transmitting an option acknowledgment message (OACK); Identifying, by the second client system, the unique number information, and transmitting a response message (ACK) including the unique number information; Transmitting, by the server system, the file data including the unique number information of the first client system and the file data including the unique number information of the second client system; And receiving, by the second client system, the file data if the unique number information of the file data transmitted through the network is the same as the unique number information thereof. The method of claim 8, wherein the unique number information, And assigning random unique number information to the first client system that has transmitted the first read request message, and then incrementing and assigning the random unique number information to the second client system that transmits the next read request message. How to transfer files on transfer system. The method of claim 8, wherein the extended read request message, An operating code field indicating a value for a message type; A file name field encoded with an ASCII code file name; A mode field defining a transmission mode; An option field for supporting multiple client systems; And A file transfer method in a file transfer system including a mask bit field for defining a value of an option field. The method of claim 8, wherein the option acceptance message, An operating code field indicating a value for a message type; Multiple client fields to support multiple client systems; And And a unique number field for indicating unique number information allocated to the client system. The method of claim 8, If the server system does not support the multi-client option function, if an extended read request message is sent from any client system requesting the multi-client file transfer, the server system further includes sending an error message to the client. File transfer method in a file transfer system, characterized in that. The method of claim 8, If the server system does not support the multi-client option function, if an extended read request message is sent from any client system requesting the multi-client file transfer, the server system adds only the functions that the server system can support to accommodate the option. And transmitting an acknowledgment message (OACK). The method of claim 8, wherein the file data transfer, And transmitting file data including unique number information allocated to a corresponding client system and block number information for guaranteeing a sequence of the file. 10. The system of claim 8, wherein each client system comprises: Recognizes the unique number information and the block number information of the file data transmitted from the server system, and receives the file data if the unique number information is assigned to itself, and includes a response message including the block number information and the unique number information. A file transfer method in a file transfer system, characterized by transmitting (ACK).