/* adapted from Sample 25_2 from "Computer Networks and Internets, 2nd ed by Comer */
/* sockserver.c - code for example server program that uses TCP */

#ifndef unix
#define WIN32
#include <windows.h>
#include <winsock.h>
#else
#define closesocket close
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#endif

#include <stdio.h>
#include <string.h>

#define PROTOPORT       5193            /* default protocol port number */
#define QLEN            6               /* size of request queue        */

int     visits      =   0;              /* counts client connections    */
/*------------------------------------------------------------------------
 * Program:   server
 *
 * Purpose:   allocate a socket and then repeatedly execute the following:
 *              (1) wait for the next connection from a client
 *              (2) send a short message to the client
 *              (3) close the connection
 *              (4) go back to step (1)
 *
 * Syntax:    server [ port ]
 *
 *               port  - protocol port number to use
 *
 * Note:      The port argument is optional.  If no port is specified,
 *            the server uses the default given by PROTOPORT.
 *
 *------------------------------------------------------------------------
 */
main(argc, argv)
    int     argc;
    char    *argv[];
{
    struct  hostent  *ptrh;  /* pointer to a host table entry       */
    struct  protoent *ptrp;  /* pointer to a protocol table entry   */
    struct  sockaddr_in sad; /* structure to hold server's address  */
    struct  sockaddr_in cad; /* structure to hold client's address  */
    int     sd, sd2;         /* socket descriptors                  */
    int     port;            /* protocol port number                */
    int     alen;            /* length of address                   */
    char    buf[1000];       /* buffer for string the server sends  */
    char    ubuf[100];       /* buffer for user string              */
    
#ifdef WIN32
    WSADATA wsaData;
    WSAStartup(0x0101, &wsaData);
#endif
    memset((char *)&sad,0,sizeof(sad)); /* clear sockaddr structure */
    sad.sin_family = AF_INET;         /* set family to Internet     */
    sad.sin_addr.s_addr = INADDR_ANY; /* set the local IP address   */
    
    /* Check command-line argument for protocol port and extract    */
    /* port number if one is specified.  Otherwise, use the default */
    /* port value given by constant PROTOPORT                       */
    
    if (argc > 1) {                 /* if argument specified        */
	port = atoi(argv[1]);   /* convert argument to binary   */
    } else {
	port = PROTOPORT;       /* use default port number      */
    }
    if (port > 0)                   /* test for illegal value       */
	sad.sin_port = htons((u_short)port);
    else {                          /* print error message and exit */
	fprintf(stderr,"bad port number %s\n",argv[1]);
	exit(1);
    }
    
    /* Map TCP transport protocol name to protocol number */
    
    if ( ((int)(ptrp = getprotobyname("tcp"))) == 0) {
	fprintf(stderr, "cannot map \"tcp\" to protocol number");
	exit(1);
    }
    
    /* Create a socket */
    
    sd = socket(PF_INET, SOCK_STREAM, ptrp->p_proto);
    if (sd < 0) {
	fprintf(stderr, "socket creation failed\n");
	exit(1);
    }
    
    /* Bind a local address to the socket */
    
    if (bind(sd, (struct sockaddr *)&sad, sizeof(sad)) < 0) {
	fprintf(stderr,"bind failed\n");
	exit(1);
    }
    
    /* Specify size of request queue */
    
    if (listen(sd, QLEN) < 0) {
	fprintf(stderr,"listen failed\n");
	exit(1);
    }
    
    /* Main server loop - accept and handle requests */
    
    while (1) {
	alen = sizeof(cad);
	if ( (sd2=accept(sd, (struct sockaddr *)&cad, &alen)) < 0) {
	    fprintf(stderr, "accept failed\n");
	    exit(1);
	}
	if (recv(sd2, ubuf, sizeof(ubuf), 0) > 0) {
	    visits++;
	    sprintf(buf, "Hello %s, you are visitor number %d to this server\n",
		    ubuf, visits);
	    send(sd2,buf,strlen(buf),0);
	}
	closesocket(sd2);
    }
}