A UNIX socket client

client.c

// Usage:
// client <address> <port>

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <strings.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <sys/un.h>

int main(int argc, char *argv[])
{
  if (argc < 3)
    exit(1);

  // 1. Create a socket
  int clientSocket = socket(AF_INET, SOCK_STREAM, 0);
  if (socket == -1) {
    perror("socket() error");
    exit(errno);
  }

  puts("Socket created");

  // 2. Create a structure to hold the server's address
  struct sockaddr_in serverAddress;
  bzero(&serverAddress, sizeof(serverAddress));
  serverAddress.sin_family = AF_INET;
  if (inet_aton(argv[1], &serverAddress.sin_addr)) {
    perror("inet_aton() error");
    exit(errno);
  }
  serverAddress.sin_port = htons(atoi(argv[2]));

  // 3. Connect to the newly created address
  if (connect(clientSocket, (struct sockaddr *) &serverAddress, sizeof(serverAddress))) {
    perror("connect() error");
    exit(errno);
  }

  puts("Socket connected");

  // 4. Communicate with the server
  char c;
  while ((c = getchar()) != EOF) {
    int bytesSent = send(clientSocket, &c, 1, 0);
    if (bytesSent < 0) {
      perror("error while sending a byte");
      exit(errno);
    }
  }

  close(clientSocket);

  return 0;
}