rpcgen Command in Linux

The rpcgen command in Linux is a powerful tool used to generate C code to implement an RPC (Remote Procedure Call) protocol. It takes an RPC protocol description file as input and produces C code that can be compiled and linked with your application.

The rpcgen command is essential for developers working with RPC services, as it simplifies the process of creating client and server programs that communicate over a network.

Table of Contents

Here is a comprehensive guide to the options available with the rpcgen command −

• Understanding rpcgen Command
• Syntax of rpcgen Command
• rpcgen Command Options
• Examples of rpcgen Command in Linux
• Customizing the Generated Code

Understanding rpcgen Command

This command simplifies the process of creating client and server programs that communicate over a network by automating the generation of the necessary code.

Developers can use various options with rpcgen to customize the generated code, such as generating ANSI C compliant code, creating multi-thread safe code, and specifying output files. By using the rpcgen command, developers can efficiently build and maintain reliable RPC-based systems in Linux environments.

The rpcgen command reads an RPC protocol description file (with a .x extension) and generates several C source files. These files include −

• Header file (.h) − Contains definitions of data types and function s.
• XDR file (_xdr.c) − Contains functions for encoding and decoding data types using XDR (External Data Representation).
• Server file (_svc.c) − Contains the server-side implementation of the RPC service.
• Client file (_clnt.c) − Contains the client-side implementation of the RPC service.

Syntax of rpcgen Command

The basic syntax of the rpcgen command is as follows −

rpcgen [options] file.x

Where,

• options − Various options to control the behavior of the command.
• file.x − The RPC protocol description file.

rpcgen Command Options

Here are some commonly used options with the rpcgen command −

Examples of rpcgen Command in Linux

The rpcgen command in Linux is a powerful tool used to generate C code for implementing RPC (Remote Procedure Call) protocols. It reads an RPC protocol description file (with a .x extension) and produces several C source files, including header files, XDR (External Data Representation) routines, server-side stubs, and client-side stubs.

Let's explore some examples of using the rpcgen command with detailed explanations.

• Basic Usage
• Generating All Files
• Generating ANSI C Compliant Code
• Generating MT-Safe Code
• Generating Only the Header File
• Generating Only the XDR Routines
• Generating Only the Server-Side Stubs
• Generating Only the Client-Side Stubs
• Specifying the Output File

Basic Usage

Consider a simple RPC protocol description file example.x −

/* example.x */
program EXAMPLE_PROG {
	version EXAMPLE_VERS {
		int ADD(int, int) = 1;
	} = 1;
} = 0x20000001;

This file defines an RPC program EXAMPLE_PROG with one version EXAMPLE_VERS and one procedure ADD that takes two integers as arguments and returns an integer.

To generate the C code for this protocol, use the following command −

rpcgen example.x 

This command generates the following files −

• example.h − Header file with definitions and function s.
• example_xdr.c − XDR routines for encoding and decoding data types.
• example_svc.c − Server-side implementation of the RPC service.
• example_clnt.c − Client-side implementation of the RPC service.

Generating All Files

To generate all files, including sample client and server main programs, use the -a option −

rpcgen -a example.x

This command generates the following additional files −

• example_server.c − Sample server main program.
• example_client.c − Sample client main program.
• Makefile − Makefile to compile the generated code.

Generating ANSI C Compliant Code

To generate ANSI C compliant code, use the -C option −

rpcgen -C example.x

This command ensures that the generated code adheres to ANSI C standards.

Generating MT-Safe Code

To generate multi-thread safe code, use the -M option −

rpcgen -M example.x

This command generates code that is safe to use in multi-threaded applications.

Generating Only the Header File

To generate only the header file, use the -h option −

rpcgen -h example.x

This command generates only the example.h file.

Generating Only the XDR Routines

To generate only the XDR routines, use the -c option −

rpcgen -c example.x

This command generates only the example_xdr.c file.

Generating Only the Server-Side Stubs

To generate only the server-side stubs, use the -m option −

rpcgen -m example.x

This command generates only the example_svc.c file.

Generating Only the Client-Side Stubs

To generate only the client-side stubs, use the -l option −

rpcgen -l example.x

This command generates only the example_clnt.c file.

Specifying the Output File

To specify the output file, use the -o option −

rpcgen -o custom_output.c example.x

This command generates the output in the specified file custom_output.c.

Customizing the Generated Code

You can customize the generated code by modifying the RPC protocol description file. For example, you can define complex data types and procedures with multiple arguments.

Consider the following example −

/* complex_example.x */
struct complex_data {
	int id;
	string name<>;
};

program COMPLEX_PROG {
	version COMPLEX_VERS {
		complex_data GET_DATA(int) = 1;
		int UPDATE_DATA(complex_data) = 2;
	} = 1;
} = 0x20000002;

This file defines a complex data type complex_data and two procedures GET_DATA and UPDATE_DATA.

To generate the C code for this protocol, use the following command −

rpcgen example.x

This command generates the necessary files to implement the RPC service with complex data types.

Integrating with Makefile

You can integrate the rpcgen command with a Makefile to automate the build process. Here is an example −

Makefile
CC = gcc
CFLAGS = -Wall -g
RPCGEN = rpcgen

all: example_server example_client

example_server: example_server.o example_svc.o example_xdr.o
	$(CC) $(CFLAGS) -o $@ $^

example_client: example_client.o example_clnt.o example_xdr.o
	$(CC) $(CFLAGS) -o $@ $^

example_server.o: example_server.c example.h
	$(CC) $(CFLAGS) -c $<

example_client.o: example_client.c example.h
	$(CC) $(CFLAGS) -c $<

example_svc.o: example_svc.c example.h
	$(CC) $(CFLAGS) -c $<

example_clnt.o: example_clnt.c example.h
	$(CC) $(CFLAGS) -c $<

example_xdr.o: example_xdr.c example.h
	$(CC) $(CFLAGS) -c $<

example.h: example.x
	$(RPCGEN) -h $<

example_svc.c: example.x
	$(RPCGEN) -m $<

example_clnt.c: example.x
	$(RPCGEN) -l $<

example_xdr.c: example.x
	$(RPCGEN) -c $<

clean:
	rm -f *.o example_server example_client example.h example_svc.c example_clnt.c example_xdr.c 

This automates the process of generating the RPC code and compiling the client and server programs.

Conclusion

The rpcgen command is a versatile and powerful tool for generating C code to implement RPC protocols in Linux. By understanding its various options and how to use them, you can effectively create client and server programs that communicate over a network.

Whether you're a developer working with RPC services or a system administrator managing networked applications, mastering the rpcgen command will enhance your ability to build and maintain reliable and efficient RPC-based systems.