JP3408435B2 - Code conversion device and conversion method in FTP server and recording medium recording code conversion program - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an FTP (File Tra
The present invention relates to a code conversion device and conversion method used when transferring a text file containing a 2-byte code in an nsfer protocol) server.

[0002]

2. Description of the Related Art In the FTP protocol standard, ASCII is used as a data representation on a line when a text file is transferred.
(American Standard Code for Information Interchan
ge) and EBCDIC (Extended Binary Coded Decimal)
Interchange Code) is defined as two types of 1-byte code. With the 1-byte code, a conversion code can be dynamically selected for each file transfer. However, since the 2-byte code is not specified at all, it is impossible to dynamically select the conversion code. This is FTP
Is a protocol defined in the United States that uses only 1-byte code, and 2-byte code is not considered. Regarding this, protocol standards (RFC
Although it is necessary to standardize the 2-byte code data expression by extending (Request for Comments) 959), this is not an essential solution. The reason is that FTP is used as a file transfer means between heterogeneous computer systems.
It is already widely used in countries that use bytecode,
This is because it is not a solution to these popular systems.

For this reason, the code conversion process in the transfer of a text file including a 2-byte code by the conventional FTP has been realized by one of the following methods.

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

Method 2: A method in which code conversion is performed in the FTP server by referring to code conversion correspondence information that associates the client information (host name, user name, file name, etc.) with the code to be used in advance.

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

[0007]

However, these conventional techniques have the following problems.

The first problem is that method 1 is a method that can be used only for routine file transfer work and is applicable only to extremely limited uses.

A second problem is that in the method 2, the FTP client that cannot be connected to other than the previously defined partner client cannot be connected, and the connectable FTP clients are limited. There is a problem that the conversion code cannot be selected dynamically. FTP
In the case of a server, it is not possible to select the file transfer partner, that is, the FTP client.
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 can be applied to a limited application.

The third problem is that with regard to method 3, there is almost no system having a 2-byte code conversion function like method 3 in personal computers and FTP clients operating in the UNIX system which are now widely used. Is.

Therefore, assuming file transfer with most of these FTP clients that do not have a code conversion function, it is necessary to provide a method in which the conversion code can be dynamically selected on the FTP server side. Therefore, an object of the present invention is 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 problems, the invention according to claim 1 provides an FTP server and an FTP client.
Data connection to transfer data to and from the client
And an instruction from the FTP client to the FTP server
Two paths to the control connection that transfers the command
Use, this does parameter added to the FTP server file name specified at the time of the file transfer request from an FTP client, and allows the identification of 2-byte code of the data on the data connection is the additional parameters, the FTP server an apparatus for performing the 2-byte code translation using code computers running analyzes the FTP protocol commands transmitted from the FTP client through the <br/> control connection, FTP
The above parameter is specified in the file name on the server side
This parameter is checked if it is specified.
Identification of 2-byte code of data when transferring files
A protocol analysis section for performing the data transferred via the data connection, the parameter is specified
If it has, it determines one of the code conversion table according a plurality of code conversion tables in the analysis results of the proto <br/> Col analysis unit, when said parameter is not specified,
Is it 1-byte code identification information specified before file transfer?
And a code conversion processing unit that determines a code conversion table and performs code conversion.

According to the second aspect of the invention, when the analysis result in the protocol analysis unit is a user authentication request,
Authenticate the user by referring to the user management information stored in advance, and use it in the authenticated user information 2
When the identification information of the bytecode is registered, the predetermined value of the 2-byte code used in the file transfer process from this user is characterized by this identification information. According to the invention of claim 3, the code conversion processing unit immediately after reading the data from the transfer file at the time of transmission from the FTP server to the FTP client,
It is characterized in that when receiving from the P client to the FTP server, it is performed immediately before writing the received data to the transfer file.

The invention according to claim 4 is the FTP server.
Data transfer between the client and the FTP client.
Connection and the FTP client to the FT
A control connection that transfers the command to the P server
Using the two paths of , the parameter is added to the file name of the FTP server side specified at the time of file transfer request from this FTP client.
To allow the identification of 2-byte code of the data on the data connection, the A method of performing a 2-byte code translation using the computer code that FTP server is operating, transmitted from the FTP client through the control connection The analyzed FTP protocol command is analyzed, and the parameter is specified in the file name on the FTP server side.
If specified, it is checked whether it is specified
2 bytes of data when transferring a file from this parameter
A protocol analysis process of performing identification code, the data transferred via the data connection, the parameter
If over data is specified to determine the code conversion table according a plurality of code conversion tables in the analysis results for the protocol analysis process, the parameters are specified
If not, the 1-byte code specified before the file transfer
And a code conversion process for performing code conversion by determining a code conversion table from the code identification information .

The invention described in claim 5 is a computer-readable recording medium in which a program for code conversion executed in the code conversion device in the FTP server according to claim 1 is recorded.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION 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 provides 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 referred to as an FTP client). Figure 1
In the above, between the FTP server 1 and the FTP client 2, there are a data connection 3 which is a communication path for transferring actual file data, and a communication path for transmitting and receiving electronic messages such as user authentication and file transfer instructions. Two communication paths of a certain control connection 4 are used.
Of these, 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 ends, and the control connection 4 is FT.
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 through the control connection 4 are finely specified in RFC959 which is a protocol standard of FTP. FIG. 2 is an excerpt of the 1-byte code instruction command C1 and the file transfer instruction command C2 related to the present invention among the FTP protocol commands defined by RFC959.

Although the character code on the control connection is defined as ASCII in FTP, 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, <type-code> is a code type "A" (ASCII) (default when omitted), "E" (EBCDI
C) or "I" (image data) character, <CRLF> is a line feed character. Also, the file transfer instruction command C2
Is a character string of "RETR" indicating transfer to the client, "STOR" indicating transfer for new / replacement of file from client, or transfer "APPE" for additional storage of file from client , A space character, and <pathnam which is a character string indicating the file name on the server side.
It consists of the e> parameter and a newline character.

As shown in FIG. 2, RFC 959 does not stipulate a 2-byte code designating command, and when transferring a file by FTP, even if the code of the data flowing on the data connection 3 is a 2-byte code, 2 It is not assumed that the FTP server 1 performs the code conversion in consideration of the byte code.

However, in Japan and other countries that use 2-byte codes, various 2-byte codes are widely used, and conventionally, 2-byte codes are converted by the method described in the section of the prior art. . However, the use range of each of these methods is limited, and like the 1-byte code, the 2-byte code conversion is dynamically performed on the FTP server 1 by recognizing the code of the data flowing on the data connection 3 at the time of file transfer. It has been widely desired to provide a method of doing so.

Therefore, according to the present invention, the file transfer instruction command specified in RFC959 is expandedly interpreted (FIG. 3), and a parameter is added to the file name on the FTP server 1 side specified at the time of the file transfer request from the FTP client 2. , It is possible to identify the 2-byte code of the data on the data connection 3 with this added parameter.
The method for converting the 2-byte code into the code used by the computer on which the TP server 1 operates has been defined. The present invention is
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 can be read by a computer. It can be recorded on various recording media and distributed.

Next, embodiments of the present invention will be described in detail. Referring to FIG. 1, one embodiment of an FTP communication system of the present invention is that 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 a file transfer between them. Connection 3 and FTP client 2 to FTP
It is composed of two communication paths of the 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 the FTP protocol command transmitted from the FTP client 2 via the control connection 4, and the 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 the data transferred via the data connection 3 are converted into a plurality of code conversion tables 1 (10).
-1), ..., A code conversion processing unit 9 that performs code conversion by selecting an appropriate code conversion table from the code conversion table group 10 including the code conversion table N (10-N).
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 analysis unit 6
Analyzes and executes protocol commands, which are various processing requests, from the FTP client 2, and returns the processing results to the FTP client 2 as a protocol command response. The present invention is mainly characterized by the configuration and operation of the protocol analysis unit 6, and details of the configuration and operation of the protocol analysis unit 6 will be described later.

The user authenticating section 7 refers to the user management information 8 to perform user authentication when the analysis result of the protocol analyzing section 6 is a user authentication request. At this time, if the identification information of the 2-byte code to be used is registered in the authenticated user information, the default value of the 2-byte code used in the file transfer process from this user is determined by this identification information. I'll do 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 code conversion processing using the determined code conversion table. Code conversion processing is done by FTP
It is performed immediately after reading the data from the transfer file 11 when transmitting from the server 1 to the FTP client 2, and immediately before writing the received data into the transfer file 11 when receiving from the FTP client 2 to the FTP server 1.

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

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

In the FTP server adopting this method, the <pathname> parameter is expandedly interpreted 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 character following it specifies the 2-byte code of the transfer data. <pathnam
The e> parameter is the data that is input as a remote file name each time file transfer is performed in the widely used FTP client. In the case of the FTP server that adopts this method, the delimiter character and 2-byte code identification are added after the remote file name. Will be input.

As the delimiter character, a character other than a space which is not allowed to be used in a file name in the file system of the server can be used. The 2-byte code is identified by a character indicating the type of the 2-byte code. For example, the character "S" is a shift JIS code, the character "E" is an EUC (Exended UNIX Code) code, and the character "U" is a character.
Unicode can be used.

Next, the processing of the protocol analysis unit 6 of FIG. 1 will be described in detail with reference to the flowchart of FIG. 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 passed to the protocol analysis unit 6 (step S1). Next, the received protocol command is analyzed to identify whether it is a file transfer instruction command (step S2). The present invention does not particularly refer to the case where the command is not a file transfer instruction command, and each request process is executed (step S
3). File transfer command, ie RETR, STOR,
If the command is one of APPE, then the <pathname> parameter, which is an essential parameter, is analyzed (step S4).

The following processing is newly added in the present invention, and it is checked whether the extension parameter described in FIG. 3 is designated in the <pathname> parameter (step S5), and if it is designated. Identify the 2-byte code of the data at the time of file transfer from the extended parameter,
A code conversion table used for 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 of FIG. 1 (step S
6). If the extended parameter is not specified in the <pathname> parameter or the format is invalid, ASCII, EBCDI is calculated from the 1-byte code identification information specified before the file transfer.
The code conversion table for either C or IMAGE (image) is determined (step S7).

Based on the code conversion table thus determined, the code conversion processing unit 9 performs the code conversion process between the code of the transfer file 11 and the data connection 3 (step S8).

[0036]

The first effect of the present invention is F, which is currently widespread.
It is possible to select a 2-byte code for a TP client. The reason is that, as described in the section of the problem to be solved by the invention, the FTP client which is now widely used does not have the 2-byte code conversion function. The second effect is that the 2-byte code to be converted can be dynamically selected at the time of file transfer. The reason is, as described in the section of the prior art, in the correspondence of the static code conversion table by the user management information and the like, the scope of application is only the file transfer business of a fixed type, and an arbitrary FTP client at any time. This is because it cannot be applied when transferring any file.

[Brief description of drawings]

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

[Explanation of symbols]

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

Claims (5)

(57) [Claims] 1. An FTP server and an FTP client
Data connection for transferring data between the two and the FTP
Transfer the command from the client to the FTP server
Using two paths with the control connection to be sent, add parameters to the file name on the FTP server side specified when requesting a file transfer from this FTP client,
To allow the identification of 2-byte code of the data on the data connection is the additional parameters, the FTP
An apparatus for performing the 2-byte code translation using the computer code for the server to operate analyzes the FTP protocol commands transmitted from the FTP client through the control connection, F
When the parameter is specified in the file name on the TP server side
Inspect whether or not the
The 2-byte code of the data when transferring the file from the meter
A protocol analysis section for performing identification, the data transferred via the data connection,
If the parameter is specified, determines one of the code conversion table according a plurality of code conversion tables in the analysis results of the protocol analyzer, the parameter
Is specified, the file was instructed before the file transfer.
Determine code conversion table from 1-byte code identification information
And a code conversion processing unit that performs code conversion. 2. When the analysis result in the protocol analysis unit is a user authentication request, user authentication is performed by referring to the user management information stored in advance, and 2. When the identification information of the 2-byte code used for is registered, the default value of the 2-byte code used in the file transfer process from this user is determined by this identification information. Code conversion device in FTP server. 3. The code conversion processing unit, when transmitting from the FTP server to the FTP client, immediately after reading the data from the transfer file, sends the FT from the FTP client.
2. The FT according to claim 1, wherein when receiving to the P server, it is performed immediately before writing the received data to the transfer file.
Code conversion device in P server. 4. An FTP server and an FTP client
Data connection for transferring data between the two and the FTP
Transfer the command from the client to the FTP server
Using two paths with the control connection to be sent, add parameters to the file name on the FTP server side specified when requesting a file transfer from this FTP client,
To allow the identification of 2-byte code of the data on the data connection is the additional parameters, the FTP
A method of performing 2-byte code translation using the computer code for the server to operate analyzes the FTP protocol commands transmitted from the FTP client through the control connection, F
When the parameter is specified in the file name on the TP server side
Inspect whether or not the
The 2-byte code of the data when transferring the file from the meter
A protocol analysis process of performing identification, the data transferred via the data connection,
If the parameter is specified to determine the code conversion table according a plurality of code conversion tables in the analysis results for the protocol analysis process, the parameters
If not specified, 1 specified before file transfer
A code conversion method in an FTP server, comprising a code conversion process of determining a code conversion table from bytecode identification information and performing code conversion. 5. A computer-readable recording medium recording a program for code conversion executed by the code conversion device in the FTP server according to claim 1.