SOCKETS CLIENT/SERVER [GCC]

================
client.c
================

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

int main()
{
  int sockfd;
  int len;
  struct sockaddr_in address;
  int result;
  char ch = 'A';

  sockfd = socket(AF_INET, SOCK_STREAM, 0);

  address.sin_family = AF_INET;
  address.sin_addr.s_addr = inet_addr("127.0.0.1");
  address.sin_port = 9734;
  len = sizeof(address);

  result = connect(sockfd, (struct sockaddr *)&address, len);

  if(result == -1) {
    perror("oops: client");
    exit(1);
  }
 
  write(sockfd, &ch, 1);
  read(sockfd, &ch, 1);
  printf("char from server = %c\n", ch);
  close(sockfd);
  exit(0);
}


================
server.c
================

#include <sys/types.h>
#include <sys/socket.h>
#include <stdio.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <unistd.h>

int main()
{
  int server_sockfd, client_sockfd;
  int server_len, client_len;
  struct sockaddr_in server_address;
  struct sockaddr_in client_address;

  server_sockfd = socket(AF_INET, SOCK_STREAM, 0);

  server_address.sin_family = AF_INET;
  server_address.sin_addr.s_addr = inet_addr("127.0.0.1");
  server_address.sin_port = 9734;
  server_len = sizeof(server_address);
  bind(server_sockfd, (struct sockaddr *)&server_address, server_len);

  listen(server_sockfd, 5);
  while(1) {
    char ch;

    printf("server waiting\n");

    client_len = sizeof(client_address);
    client_sockfd = accept(server_sockfd,
			   (struct sockaddr *)&client_address, &client_len);

    read(client_sockfd, &ch, 1);
    ch++;
    write(client_sockfd, &ch, 1);
    close(client_sockfd);
  }
}