#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/select.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <string.h>
#include <netinet/in.h>

int main(int argc, char* argv[])
{
  int status;
  int server_sock;
  int client_sock;
  int accept_sock;

  /* Server setup */
  sockaddr_in server_sin;
  server_sin.sin_family = AF_INET;
  server_sin.sin_addr.s_addr = htonl(INADDR_ANY);
  server_sin.sin_port = htons(short(8888));
  memset(server_sin.sin_zero, 0, sizeof(server_sin.sin_zero));

  /* Client Setup */
  sockaddr_in client_sin;
  client_sin.sin_family = AF_INET;
  client_sin.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
  client_sin.sin_port = htons(short(8888));
  memset(client_sin.sin_zero, 0, sizeof(client_sin.sin_zero));

  pid_t pid;
  if ((pid = fork())==0) {
    sleep(1);
    /* Client */
    client_sock = socket(AF_INET, SOCK_STREAM, 0);
    //fcntl(client_sock, F_SETFD, FD_CLOEXEC);
  
    // initiate connection
    status = connect(client_sock, (struct sockaddr *) &client_sin,
		     sizeof(sockaddr));

    printf("connect\n");

    size_t num;

    num = write(client_sock, "one\n", 5);

    sleep(2);
    close(client_sock);

  } else {
    /* Server */
    server_sock = socket(AF_INET, SOCK_STREAM, 0);
  
    //fcntl(server_sock, F_SETFD, FD_CLOEXEC);

    status = bind(server_sock, (struct sockaddr *) &server_sin,
		  sizeof(struct sockaddr));
    
    if (status != -1) {
      status = listen(server_sock, SOMAXCONN);
      printf("listen %d\n", status);
    }

    accept_sock = accept(server_sock, NULL, NULL);
    printf("accept %d\n", accept_sock);

#define BUFSIZE 64
    char buf[BUFSIZE];
    size_t num;
    memset(buf, 0, BUFSIZE);

    sleep(2);
    if ((status = fcntl(accept_sock, F_GETFL))<0) {
      printf("fcntl get:%s\n", strerror(errno));
      exit(0);
    }
    printf("fcntl get %X\n", status);
    status |= O_NONBLOCK;
    printf("fcntl set %X\n", status);
    if (fcntl(accept_sock, F_SETFL, status)==-1) {
      printf("fcntl set non-blocking:%s\n", strerror(errno));
      exit(0);
    }
    num = read(accept_sock, buf, BUFSIZE);
    printf("a:%s\n", buf);

    memset(buf, 0, BUFSIZE);
    num = read(accept_sock, buf, BUFSIZE);

    printf("b:%s\n", buf);

    if ((status = fcntl(accept_sock, F_GETFL))<0) {
      printf("fcntl get:%s\n", strerror(errno));
      exit(0);
    }
    printf("fcntl get %X\n", status);
    status &= (~(O_NONBLOCK));
    printf("fcntl set %X\n", status);
    if (fcntl(accept_sock, F_SETFL, status)==-1) {
      printf("fcntl set blocking:%s\n", strerror(errno));
      exit(0);
    }
  }
}