/*
 * An modified example of server using TCP protocol.
 *  (UNIX NETWORK PROGRAMMING, by Richard Stevens,
 *        Prentice Hall, 1990, pp. 284-286)
 *
 * The program forks a process for each cli program.
 * It reads one message from a socket which is connected
 * with the cli program.  It prints out the message on the stderr,
 * modifies the message, and sends the message back to the cli program.
	Also, it uses a select statement to choose between read()
	and recv(). This is because it is upgraded to be able to
	receive out of band data.
 */

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

#include "message.h"

#define SERV_HOST_ADDR "156.12.127.18"
/* acad's Internet address, defined in /etc/hosts */

#define PORT 15010
#define BACKLOG 15010

extern int errno;

void sigurg_handler(int);

char    oob;
int sockfd, clifd;

void die(char *msg)
{ perror(msg);
  exit(-1);
}

int main(void)
{
    struct sockaddr_in myaddr;
    char buf[BUFSIZ];
    ssize_t nbytes;
    sigset_t sset, oset;
    sigemptyset(&sset);
    sigaddset(&sset, SIGURG);

    if (-1 == (sockfd = socket(AF_INET, SOCK_STREAM, 0)))
        die("socket()");

    (void)memset(&myaddr, 0, sizeof(myaddr));

    myaddr.sin_family = AF_INET;
    myaddr.sin_port = htons(PORT);
    myaddr.sin_addr.s_addr = htonl(INADDR_ANY);

    if (-1 == bind(sockfd, (struct sockaddr*)&myaddr, sizeof(myaddr)))
        die("bind()");

    if (-1 == listen(sockfd, BACKLOG))
        die("listen()");

    if (-1 == fcntl(sockfd, F_SETOWN, getpid()))
        die("fcntl()");

    if (SIG_ERR == signal(SIGURG, sigurg_handler))
            die("signal()");
    for (;;)
    {
        /* block SIGURG when accepting the connection */
//      sigprocmask(SIG_SETMASK, &sset, &oset);
        printf("bloking in accept()\n");
        if (-1 == (clifd = accept(sockfd, NULL, NULL)))
            die("accept()");

        /* unblock SIGURG */
//      sigprocmask(SIG_SETMASK, &oset, NULL);

        printf("recv()ing normal data\n");
        nbytes = recv(clifd, buf, sizeof(buf), 0);
        buf[nbytes] = 0; /* null-terminate */

        printf("%s", buf);

    }

    close(sockfd);
}

void
sigurg_handler(int signo)
{
    char buff[100];
    ssize_t nbytes;

    printf("Signal %d SIGURG received\n",signo);
    if (clifd != 0)
    {
        if (-1 == (nbytes = recv(clifd, buff, sizeof(buff) - 1, MSG_OOB)))
            die("recv() in sigurg_handler()");

        buff[nbytes] = 0;
        printf("from sigurg_handler: received \"%s\"\n", buff);
    }
    else
    {
        printf("clifd = %d\n", clifd);
        exit(1);
    }
}