sddslogclient.c File Reference

A simple TCP client for sending commands to a server. More...

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>

Go to the source code of this file.

Macros
#define	BUFLEN   16384

Functions
void	error_exit (const char *msg)
int	process_command (char *buffer, int sockfd)
int	main (int argc, char *argv[])

Detailed Description

A simple TCP client for sending commands to a server.

This program establishes a TCP connection to a specified server and port, sends commands either from the command line arguments or interactively from the user, and processes the server's responses. The client supports persistent connections, allowing multiple commands to be sent over a single socket until a "disconnect" command is issued.

Usage

./sddslogclient <hostname> <port> [<command> ...]

• hostname: The server's hostname or IP address.
• port: The port number on which the server is listening.
• <command>: (Optional) One or more commands to send to the server initially.

If no commands are provided as arguments, the client enters an interactive mode where the user can input commands manually.

Functions

• void error(const char *msg): Prints an error message and exits the program.
• int processCommand(char *buffer, int sockfd): Sends a command to the server and processes the response.
• int main(int argc, char *argv[]): The main function that handles argument parsing, socket creation, connection, and command processing.

Example

To connect to a server at localhost on port 8080 and send the commands HELLO and STATUS:

./sddslogclient localhost 8080 HELLO STATUS

After sending the initial commands, the client will enter interactive mode where additional commands can be entered until disconnect is typed.

Copyright

• (c) 2002 The University of Chicago, as Operator of Argonne National Laboratory.
• (c) 2002 The Regents of the University of California, as Operator of Los Alamos National Laboratory.

License

This file is distributed under the terms of the Software License Agreement found in the file LICENSE included with this distribution.

Author

M. Borland, R. Soliday

Definition in file sddslogclient.c.

Macro Definition Documentation

BUFLEN

#define BUFLEN   16384

Definition at line 64 of file sddslogclient.c.

Function Documentation

error_exit()

void error_exit

(

const char *

msg

)

Definition at line 67 of file sddslogclient.c.

                                 {
  perror(msg);
  exit(EXIT_FAILURE);
}

main()

int main	(	int	argc,
		char *	argv[] )

Definition at line 90 of file sddslogclient.c.

                                 {
  int sockfd, portno, arg_index;
  struct sockaddr_in serv_addr;
  struct hostent *server;
  int persist = 1;
 
  char buffer[BUFLEN];
 
  if (argc < 3) {
    fprintf(stderr, "Usage: %s hostname port [<command> [<command> ...]]\n", argv[0]);
    exit(EXIT_FAILURE);
  }
 
  portno = atoi(argv[2]);
  sockfd = socket(AF_INET, SOCK_STREAM, 0);
  if (sockfd < 0)
    error_exit("ERROR opening socket");
 
  server = gethostbyname(argv[1]);
  if (server == NULL) {
    fprintf(stderr, "ERROR, no such host\n");
    exit(EXIT_FAILURE);
  }
 
  memset(&serv_addr, 0, sizeof(serv_addr));
  serv_addr.sin_family = AF_INET;
  memcpy(&serv_addr.sin_addr.s_addr, server->h_addr, server->h_length);
  serv_addr.sin_port = htons(portno);
 
  if (connect(sockfd, (struct sockaddr *)&serv_addr, sizeof(serv_addr)) < 0)
    error_exit("ERROR connecting");
 
  for (arg_index = 3; persist && arg_index < argc; arg_index++) {
    if (snprintf(buffer, BUFLEN, "%s\n", argv[arg_index]) >= BUFLEN) {
      fprintf(stderr, "ERROR: Command too long\n");
      continue;
    }
 
    if (strcmp(buffer, "disconnect\n") == 0)
      persist = 0;
 
    printf("Processing command: %s", buffer);
    fflush(stdout);
 
    process_command(buffer, sockfd);
  }
 
  while (persist) {
    printf("Please enter the message: ");
    fflush(stdout);
 
    memset(buffer, 0, BUFLEN);
    if (fgets(buffer, BUFLEN - 1, stdin) == NULL)
      break;
 
    if (strcmp(buffer, "disconnect\n") == 0)
      persist = 0;
 
    process_command(buffer, sockfd);
  }
 
  close(sockfd);
  return EXIT_SUCCESS;
}

process_command()

int process_command	(	char *	buffer,
		int	sockfd )

Definition at line 73 of file sddslogclient.c.

                                              {
  ssize_t n;
 
  n = write(sockfd, buffer, strlen(buffer));
  if (n < 0)
    error_exit("ERROR writing to socket");
 
  memset(buffer, 0, BUFLEN);
  n = read(sockfd, buffer, BUFLEN - 1);
  if (n < 0)
    error_exit("ERROR reading from socket");
 
  printf("%s\n", buffer);
  return n;
}