tcp/ip 예제

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
void error_handling(char *message);
 
int main(int argc, char *argv[])
{
  int serv_sock;
  int clnt_sock;
 
  struct sockaddr_in serv_addr;
  struct sockaddr_in clnt_addr;
  socklen_t clnt_addr_size;
 
  char message[]="Hello World!";
 
  if(argc!=2)
  {
  printf("Usage : %s <port>\n",argv[0]);
  exit(1);
  }
 
  serv_sock=socket(PF_INET, SOCK_STREAM,0);
  if(serv_sock == -1)
    error_handling("socket() error");
 
  memset(&serv_addr,0,sizeof(serv_addr));
  serv_addr.sin_family=AF_INET;
  serv_addr.sin_addr.s_addr=htonl(INADDR_ANY);
  serv_addr.sin_port=htons(atoi(argv[1]));
 
  if(bind(serv_sock, (struct sockaddr*) &serv_addr, sizeof(serv_addr))== -1)
    error_handling("bind() error");
 
  if(listen(serv_sock, 5)==-1)
    error_handling("listen() error");
 
  clnt_addr_size=sizeof(clnt_addr);
  clnt_sock=accept(serv_sock, (struct sockaddr*)&clnt_addr, &clnt_addr_size):
  if(clnt_sock==-1)
    error_handling("accept() error");
 
  write(clnt_sock, message, sizeof(message));
  close(clnt_sock);
  close(serv_sock);
  return 0;
}
 
void error_handling(char *message)
{
  fputs(message,stderr);
  fputc('\n',stderr);
  exit(1);
}