/*
 * tcpopen.c
 *	this file contains source to open a TCP connection
 * 
 * Author(s)
 *      Stevens' "UNIX Network Programming"
 *	hacked for HPUX by Scott A. Leerssen, leerssen@issl.atl.hp.com
 * 
 * Protection Notice
 *      Copyright (c) 1997, Scott Leerssen, All rights reserved.
 *
 *      This program is free software; you can redistribute it and/or modify
 *      it under the terms of the GNU General Public License as published by
 *      the Free Software Foundation; either version 2 of the License, or
 *      (at your option) any later version.
 *
 *      This program is distributed in the hope that it will be useful,
 *      but WITHOUT ANY WARRANTY; without even the implied warranty of
 *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *      GNU General Public License for more details.
 *
 *      You should have received a copy of the GNU General Public License
 *      along with this program; if not, write to the Free Software
 *      Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#ifndef	INADDR_NONE
#define	INADDR_NONE	0xffffffff	/* should be in <netinet/in.h> */
#endif

/*
 * The following globals are available to the caller, if desired.
 */

struct sockaddr_in	tcp_srv_addr;	/* server's Internet socket addr */
struct servent		tcp_serv_info;	/* from getservbyname() */
struct hostent		tcp_host_info;	/* from gethostbyname() */

int			/* return socket descriptor if OK, else -1 on error */
tcp_open(host, service, port)
char	*host;		/* name or dotted-decimal addr of other system */
char	*service;	/* name of service being requested */
			/* can be NULL, iff port > 0 */
int	port;		/* if == 0, nothing special - use port# of service */
			/* if < 0, bind a local reserved port */
			/* if > 0, it's the port# of server (host-byte-order) */
{
    int		fd, resvport;
    unsigned long	inaddr;
    struct servent	*sp;
    struct hostent	*hp;

    /*
     * Initialize the server's Internet address structure.
     * We'll store the actual 4-byte Internet address and the
     * 2-byte port# below.
     */

    bzero((char *) &tcp_srv_addr, sizeof(tcp_srv_addr));
    tcp_srv_addr.sin_family = AF_INET;

    if (service != NULL) {
        if ( (sp = getservbyname(service, "tcp")) == NULL) {
            return(-1);
        }
        tcp_serv_info = *sp;			/* structure copy */
        if (port > 0)
            tcp_srv_addr.sin_port = htons(port);
        /* caller's value */
        else
            tcp_srv_addr.sin_port = sp->s_port;
        /* service's value */
    } else {
        if (port <= 0) {
            return(-1);
        }
        tcp_srv_addr.sin_port = htons(port);
    }

    /*
     * First try to convert the host name as a dotted-decimal number.
     * Only if that fails do we call gethostbyname().
     */

    if ( (inaddr = inet_addr(host)) != INADDR_NONE) {
        /* it's dotted-decimal */
        bcopy((char *) &inaddr, (char *) &tcp_srv_addr.sin_addr,
              sizeof(inaddr));
        tcp_host_info.h_name = NULL;

    } else {
        if ( (hp = gethostbyname(host)) == NULL) {
            return(-1);
        }
        tcp_host_info = *hp;	/* found it by name, structure copy */
        bcopy(hp->h_addr, (char *) &tcp_srv_addr.sin_addr,
              hp->h_length);
    }

    if (port >= 0) {
        if ( (fd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
            return(-1);
        }

    } else if (port < 0) {
        resvport = IPPORT_RESERVED - 1;
        if ( (fd = rresvport(&resvport)) < 0) {
            return(-1);
        }
    }

    /*
     * Connect to the server.
     */

    if (connect(fd, (struct sockaddr *) &tcp_srv_addr,
                sizeof(tcp_srv_addr)) < 0) {
        close(fd);
        return(-1);
    }

    return(fd);	/* all OK */
}