/*
 * 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 <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 "message.h"

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

extern int errno;

main(argc, argv)
int argc;
char *argv[];
{
    int sockfd, newsockfd, clilen, pid, err,OOB_fd;
    struct sockaddr_in cli_addr, serv_addr;
    int SERV_TCP_PORT;
    fd_set fds;
    char *pname;
    MES message, tmp;

    /* SERV_TCP_PORT is the port number on kiwi used by this
       server program */
    printf("Please input an integer which is larger than 1023.\n");
    scanf("%d", &SERV_TCP_PORT);
    if(SERV_TCP_PORT > 1023)
	printf("Please run the program cli now.\n");
    else
    { 	printf("Wrong input.\n"); exit(1); }
    
    pname = argv[0];

    /* create a socket which is one end of a communication channel */
    if((sockfd = socket(AF_INET, SOCK_DGRAM, 0)) < 0)
    { perror("server: cannot open stream socket"); exit(1); }

    /* initialize server address */
    bzero((char *) &serv_addr, sizeof(serv_addr)); /* reset */
    serv_addr.sin_family = AF_INET; /* address family: Internet */
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
         /* accept a connection on any Internet interface */
    serv_addr.sin_port = htons(SERV_TCP_PORT); /* specify port number */

    /* associate server address with the socket */
    if(bind(sockfd, (struct sockaddr *) &serv_addr, sizeof(serv_addr))
       < 0)
    { perror("server: cannot bind local address"); exit(2); }

    OOB_fd=dup(sockfd);    
    while(1)
    {
	FD_ZERO(&fds);
        FD_SET(OOB_fd,&fds);
        FD_SET(sockfd,&fds);
	clilen = sizeof(cli_addr);
        bzero((char *) &cli_addr, sizeof(cli_addr)); /* reset */
	select(10,&fds,NULL,NULL,NULL);
        if (FD_ISSET(sockfd,&fds)) {
/*		  if((err = recvfrom(sockfd, &tmp, sizeof(MES),0,
		 &cli_addr,sizeof(cli_addr))) == -1){   */
		  if((err = recv(sockfd, &tmp, sizeof(MES),0))==-1) {
		   perror("server: ordinary read"); exit(4); 
                  }

		else if (err == 0) exit(5);

		message.mtype = ntohl(tmp.mtype);
		message.number = ntohl(tmp.number);
		fprintf(stderr, "server output: %d %d\n",
			message.mtype, message.number);
        }
        if (FD_ISSET(OOB_fd,&fds)) {
	   /* Get out of band data */
	/*   if ((err=recvfrom(sockfd,&tmp,sizeof(MES),MSG_OOB,
		(struct sockaddr *) &cli_addr,sizeof(cli_addr)))==-1)	{ */ 
	   if ((err=recv(sockfd,&tmp,sizeof(MES),MSG_OOB))==-1) {
	     perror("server: read out of band"); exit(4); 
	   }

	   /* Print it out */
		message.mtype	= ntohl(tmp.mtype);
		message.number	= ntohl(tmp.number);
		fprintf(stderr,	"server OOB output: %d %d\n",
			message.mtype,	message.number);
	}
        
/*
		tmp.mtype = htonl(message.mtype + 1000);
		tmp.number = htonl(message.number + 1000);
	
		if(write(newsockfd, &tmp, sizeof(MES)) == -1)
		  { perror("server: write"); exit(6); }
*/
    }
}