JP2000132465A - Device and method for code conversion of ftp server and record medium where code converting program is recorded - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a converting device of two-byte codes which can dynamically select a conversion code on the FTP(file transfer protocol) server side. SOLUTION: A parameter is added to a file name on the side of the FTP server 1 specified when file transfer is requested by an FTP client 2 and with this added parameter, the two-byte code of data on a data connection 3 can be identified to perform two-byte code conversion to the in-use code of a computer on which the FTP server 1 runs, and the device comprises a protocol analysis part 6 which analyzes an FTP protocol command sent from the FTP client 2 through a control connection 4 and a code converting process part 9 which performs code conversion of the data transferred through the data connection 3 by selecting one code conversion table out of code conversion tables according to the analysis result of the protocol analysis part 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an FTP (File Tra
The present invention relates to a code conversion device and a conversion method used for transferring a text file including a two-byte code in a server (nsfer protocol).

[0002]

2. Description of the Related Art In the FTP protocol standard, ASCII is used as a data expression on a line when transferring a text file.
(American Standard Code for Information Interchan
ge) and EBCDIC (Extended Binary Coded Decimal)
Two types of 1-byte code (Interchange Code) are defined, and a 1-byte code can dynamically select a conversion code for each file transfer. However, since no two-byte code is specified, dynamic conversion code selection is not possible. This is FTP
Is a protocol defined in the United States that uses only one-byte codes, and does not consider two-byte codes. About this, the protocol standard (RFC
(Request for Comments) It is necessary to standardize the representation of 2-byte code data by extending 959), but this is not an essential solution. The reason is that FTP is used as a means for transferring files between different types of computer systems.
It is already widely used in countries that use bytecode,
This is because it is not a solution for these popular systems.

[0003] For this reason, conventionally, a code conversion process in the transfer of a text file including a 2-byte code by FTP has been realized by any of the following methods.

Method 1: File transfer by FTP is a method of transferring as binary data and executing code conversion before or after file transfer by executing another code conversion program.

Method 2: A method in which the FTP server performs code conversion by referring to code conversion correspondence information in which partner client information (host name, user name, file name, etc.) and a code to be used are associated in advance.

Method 3: A method in which a code to be converted at the time of file transfer is designated by an FTP client, and code conversion is performed before transfer.

[0007]

However, these conventional techniques have the following problems.

[0008] The first problem is that the method 1 is a method that cannot be used other than for routine file transfer operations and can be applied only to extremely limited uses.

[0009] The second problem is that, with regard to the method 2, the FTP client that cannot perform 2-byte code conversion with a client other than the client defined in advance and is connectable is limited. There is a problem that the conversion code cannot be selected dynamically. FTP
In the case of a server, a file transfer partner, that is, an FTP client cannot be selected.
Since it is necessary to assume a TP client and the code used by the FTP client can be recognized for the first time at the time of file transfer, it can be said that the method 2 is also a method in which the applicable applications are limited.

[0010] The third problem is that, with regard to method 3, almost no personal computer or FTP client operating on a UNIX system has a 2-byte code conversion function like method 3 at present. It is.

Therefore, assuming file transfer with most FTP clients that do not have the code conversion function, it is necessary to provide a method that allows the FTP server to dynamically select a conversion code. Accordingly, it is an object of the present invention to provide a code conversion device and a conversion method capable of dynamically selecting a conversion code on the FTP server side.

[0012]

In order to solve the above-mentioned problem, the invention according to claim 1 adds a parameter to an FTP server-side file name specified at the time of a file transfer request from an FTP client, and uses the added parameter. An apparatus which enables identification of a 2-byte code of data on a data connection and converts the 2-byte code into a code used by a computer on which an FTP server operates,
A protocol analysis unit for analyzing an FTP protocol command transmitted from the FTP client via the control connection, and one code corresponding to the data transferred via the data connection from a plurality of code conversion tables according to the analysis result of the protocol analysis unit A code conversion processing unit for selecting a conversion table and performing code conversion.

Further, according to the present invention, when the analysis result of the protocol analysis unit is a user authentication request,
User authentication is performed by referring to user management information stored in advance, and is used in the authenticated user information 2
When the identification information of the bytecode is registered, the default value of the 2-byte code used in the file transfer process from the user is determined by the identification information. Further, according to a third aspect of the present invention, when the code conversion processing unit reads the data from the transfer file at the time of transmission from the FTP server to the FTP client,
When receiving data from the P client to the FTP server, it is performed immediately before writing the received data to the transfer file.

According to a fourth aspect of the present invention, a parameter is added to the file name on the FTP server side specified at the time of a file transfer request from the FTP client, and the added parameter identifies the 2-byte code of the data on the data connection. A two-byte code conversion to a code used by a computer on which an FTP server operates, comprising: a protocol analysis step of analyzing an FTP protocol command transmitted from an FTP client via a control connection; And performing code conversion by selecting a code conversion table according to the analysis result of the protocol analysis process from the plurality of code conversion tables for the data transferred through the code conversion table.

According to a fifth aspect of the present invention, there is provided a computer-readable recording medium storing a code conversion program executed by the code conversion apparatus in the FTP server according to the first aspect.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

First, an outline of the present invention will be described with reference to the drawings. The present invention relates to an FTP service providing system (hereinafter referred to as an FTP server) which is widely used as a file transfer means between different types of computer systems.
The present invention provides a configuration in which a 2-byte code conversion type can be dynamically selected for each file transfer request from an FTP service using system (hereinafter, FTP client). FIG.
In the communication between the FTP server 1 and the FTP client 2, there is a data connection 3, which is a communication path for transferring actual file data, and a communication path for transmitting and receiving messages such as user authentication and file transfer instructions. Two communication paths of a certain control connection 4 are used.
The data connection 3 is a communication path that is opened only when data is actually transferred by file transfer or the like and is released when the transfer is completed.
It exists while the P server 1 and the FTP client 2 are connected.

Various instruction commands transmitted from the FTP client 2 to the FTP server 1 via the control connection 4 are specified in detail by RFC 959, which is an FTP protocol standard. FIG. 2 is an extract of a one-byte code instruction command C1 and a file transfer instruction command C2 related to the present invention from among FTP protocol commands defined in RFC959.

In the FTP, the character code on the control connection is defined as ASCII, but as shown in FIG.
The byte instruction command C1 is “TYPE” <SP><type-code><
CRLF>. Here, “TYPE” is a character string, <SP> is a space character, and <type-code> is a code type “A” (ASCII) (default when omitted), “E” (EBCDI
C) or the character of "I" (image data), <CRLF> is a line feed character. The file transfer instruction command C2
Is a character string of "RETR" indicating transfer to the client, "STOR" indicating transfer for new / replacement of a file from the client, or "APPE" for transfer of additional file from the client. And a space character and <pathnam, which is a character string indicating the file name on the server side
e> parameter and a line feed character.

As shown in FIG. 2, the two-byte code instruction command is not defined in RFC959, and when transferring a file by FTP, even if the code of the data flowing on the data connection 3 is a two-byte code, It is not assumed that the FTP server 1 performs code conversion in consideration of bytecode.

However, in Japan and other countries that use double-byte codes, various double-byte codes are widely used. Conventionally, double-byte codes have been converted by the method described in the section of the related art. . However, the use range of each of these methods is limited. Like the 1-byte code, the code of the data flowing on the data connection 3 at the time of file transfer is recognized and the 2-byte code conversion is dynamically performed on the FTP server 1. It has been widely desired to provide a method for performing this.

Therefore, according to the present invention, the file transfer instruction command specified in RFC 959 is expanded and interpreted (FIG. 3), and a parameter is added to the file name of the FTP server 1 specified at the time of the file transfer request from the FTP client 2. The added parameter enables identification of the 2-byte code of the data on the data connection 3, and F
A method of performing a 2-byte code conversion to a code used by a computer on which the TP server 1 operates is defined. The present invention
In this way, in file transfer with an arbitrary FTP client, an arbitrary code is dynamically selected to enable 2-byte code conversion.

The data processing in the protocol conversion unit 6, the code conversion processing unit 9 and the like shown in FIG. 1 can be realized by executing a program by a computer constituting an FTP server, and the program is computer-readable. It is possible to record it on a simple recording medium and distribute it.

Next, an embodiment of the present invention will be described in detail. Referring to FIG. 1, an FTP communication system according to an embodiment of the present invention includes an FTP server 1 that provides an FTP service, an FTP client 2 that uses the FTP service, and data that transfers actual data such as file transfer between the two. FTP from connection 3 and FTP client 2
It is composed of two communication paths of a control connection 4 for transferring various instruction commands to the server 1.

The FTP server 1 has a data connection 3
And a data transmission / reception processing unit 5 for communicating with the FTP client 2 via the control connection 4, a protocol analysis unit 6 for analyzing an FTP protocol command transmitted from the FTP client 2 via the control connection 4, an analyzed protocol When the command is a user authentication request, the user authentication unit 7 that performs user authentication processing based on the user management information 8 and converts the data transferred via the data connection 3 into a plurality of code conversion tables 1 (10
-1),..., A code conversion processing unit 9 for selecting an appropriate code conversion table from a code conversion table group 10 including a code conversion table N (10-N) and performing code conversion;
And a transfer file (storage device) 11.

Each of these means operates roughly as follows. The data transmission / reception processing unit 5 performs data transmission / reception processing between the data connection 3 and the code conversion processing unit 9 and protocol command transmission / reception processing between the control connection 4 and the protocol analysis unit 6. Protocol analyzer 6
Analyzes and executes protocol commands as various processing requests from the FTP client 2, and returns the processing results to the FTP client 2 as a protocol command response. The main feature of the present invention is the configuration and operation of the protocol analyzer 6. The configuration and operation of the protocol analyzer 6 will be described later in detail.

The user authentication unit 7 performs user authentication by referring to the user management information 8 when the result of analysis by the protocol analysis unit 6 is a user authentication request. At this time, if the identification information of the two-byte code to be used is registered in the authenticated user information, the default value of the two-byte code to be used in the file transfer process from this user is determined by the identification information. Keep it.

The code conversion processing unit 9 determines a code conversion table to be used from the code conversion table group 10 before file transfer, and performs a code conversion process using the determined code conversion table. Code conversion process is FTP
This is performed immediately after reading data from the transfer file 11 when transmitting from the server 1 to the FTP client 2, and immediately before writing received data into the transfer file 11 when receiving from the FTP client 2 to the FTP server 1.

Next, the overall operation of the present embodiment will be described in detail with reference to the flowcharts of FIGS. 1, 2, 3 and 4.

First, as shown in FIG. 2, the FTP file transfer instruction command C2 includes identification information (RETR, STOR, APPE command) of the file transfer direction and storage method, and server-side file name information (<pathname>) of the transfer file. (Path name)
Parameter).

The <pathname> parameter is expanded and interpreted by the FTP server adopting this method as shown in FIG. That is, as shown in P2, a character that is not allowed as a file name in the file system of the computer on which the FTP server operates is defined as a delimiter character, and the subsequent character specifies a 2-byte code of the transfer data. <pathnam
The e> parameter is data that is input every time a file is transferred as a remote file name in the FTP client that is widely used at present. In the case of an FTP server that adopts this method, the delimiter character and 2-byte code identification are added after the remote file name. Will be entered.

As the delimiter character, a character other than a space which is not allowed to be used for a file name in the file system of the server can be used. As the two-byte code identification, a character indicating the type of the two-byte code is, for example, a shift JIS code with the character "S", an EUC (Extended UNIX Code) code with the character "E", and a character "U".
Unicode (Unicode) can be used.

Next, the processing of the protocol analyzer 6 in FIG. 1 will be described in detail with reference to the flowchart in FIG. 4 for processing related to the present invention. When the data transmission / reception processing unit 5 receives the protocol command from the FTP client 2 received via the control connection 4, it is transferred to the protocol analysis unit 6 (step S1). Next, the received protocol command is analyzed to determine whether it is a file transfer instruction command (step S2). The case where the command is not a file transfer instruction command is not particularly mentioned in the present invention, and each request process is executed (step S
3). File transfer instruction command, that is, RETR, STOR,
If the command is one of APPE, the <pathname> parameter, which is an essential parameter, is analyzed next (step S4).

The next process is a process newly added in the present invention. It is checked whether or not the extension parameter described in FIG. 3 is designated in the <pathname> parameter (step S5). The 2-byte code of the data at the time of the file transfer is identified from the extended parameter,
The code conversion table used for the code conversion with the 2-byte code of the computer on which the FTP server operates is determined from the code conversion table group 10 in FIG. 1 (step S).
6). If no extension parameter is specified or the format is invalid in the <pathname> parameter, ASCII, EBCDI is used from the 1-byte code identification information specified before file transfer.
One of the code conversion tables of C and IMAGE (image) is determined (step S7).

Based on the code conversion table determined in this manner, the code conversion processing between the code of the transfer file 11 and the data connection 3 is performed by the code conversion processing section 9 (step S8).

[0036]

The first effect is that F which is currently widely used is widely used.
The point is that a 2-byte code can be selected with the TP client. The reason is that, as described in the section of the problem to be solved by the invention, the FTP client that is currently widely used does not have a 2-byte code conversion function. The second effect is that a 2-byte code to be converted can be dynamically selected at the time of file transfer. The reason is that, as described in the section of the prior art, in the association of the static code conversion table based on the user management information and the like, the application range is limited to a standard file transfer operation, and any FTP client can be used at any time. This is because it cannot be applied when transferring an arbitrary file.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a diagram for explaining a part of an FTP protocol command;

FIG. 3 is a diagram showing a <pathname> parameter format in a file transfer instruction command proposed by the present invention.

FIG. 4 is a flowchart showing an operation of the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 FTP server 6 Protocol analysis unit 9 Code conversion processing unit 10 Code conversion table group 10-1 to 10-N Code conversion tables 1 to N

Claims (5)

[Claims] 1. A parameter is added to a file name of an FTP server specified at the time of a file transfer request from an FTP client, and the added parameter enables identification of a 2-byte code of data on a data connection.
A device that converts a 2-byte code into a code used by a computer on which an FTP server operates, a protocol analyzing unit that analyzes an FTP protocol command transmitted from an FTP client via a control connection, and a transfer via a data connection And a code conversion processing unit for selecting one code conversion table from the plurality of code conversion tables according to the analysis result of the protocol analysis unit and performing code conversion.
Code conversion device in TP server. 2. When the analysis result of the protocol analysis unit is a user authentication request, user authentication is performed with reference to user management information stored in advance, and the user information is stored in the authenticated user information. 2. A method according to claim 1, wherein when identification information of a two-byte code to be used is registered, a default value of the two-byte code used in a file transfer process from the user is determined by the identification information. Code conversion device in FTP server. 3. When the code conversion processing unit transmits data from the FTP server to the FTP client during transmission from the FTP server, the code conversion processing unit transmits the data from the FTP client to the FTP client immediately after reading the data from the transfer file.
2. The FT according to claim 1, wherein the reception is performed immediately before writing the reception data to the transfer file at the time of reception to the P server.
Code conversion device in P server. 4. A parameter is added to an FTP server-side file name specified when a file transfer is requested from an FTP client, and the added parameter enables identification of a 2-byte code of data on a data connection.
A method of performing a 2-byte code conversion to a code used by a computer on which an FTP server operates, a protocol analysis process of analyzing an FTP protocol command transmitted from an FTP client via a control connection, and a transfer via a data connection And a code conversion step of selecting a code conversion table from the plurality of code conversion tables in accordance with the analysis result in the protocol analysis step and performing code conversion.
Code conversion method in server. 5. A computer-readable recording medium on which a program for code conversion executed in the code conversion device in the FTP server according to claim 1 is recorded.