usr/src/usr.bin/talk/look_up.c

/*
 * Copyright (c) 1983 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that this notice is preserved and that due credit is given
 * to the University of California at Berkeley. The name of the University
 * may not be used to endorse or promote products derived from this
 * software without specific prior written permission. This software
 * is provided ``as is'' without express or implied warranty.
 */

#ifndef lint
static char sccsid[] = "@(#)look_up.c   5.3 (Berkeley) %G%";
#endif /* not lint */

#include "talk_ctl.h"

/*
 * See if the local daemon has an invitation for us.
 */
check_local()
{
        CTL_RESPONSE response;
        register CTL_RESPONSE *rp = &response;

        /* the rest of msg was set up in get_names */
        msg.ctl_addr = *(struct sockaddr *)&ctl_addr;
        msg.ctl_addr.sa_family = htons(msg.ctl_addr.sa_family);
        /* must be initiating a talk */
        if (!look_for_invite(rp))
                return (0);
        /*
         * There was an invitation waiting for us,
         * so connect with the other (hopefully waiting) party
         */
        current_state = "Waiting to connect with caller";
        do {
                if (rp->addr.sa_family != AF_INET)
                        p_error("Response uses invalid network address");
                errno = 0;
                if (connect(sockt, &rp->addr, sizeof (rp->addr)) != -1)
                        return (1);
        } while (errno == EINTR);
        if (errno == ECONNREFUSED) {
                /*
                 * The caller gave up, but his invitation somehow
                 * was not cleared. Clear it and initiate an
                 * invitation. (We know there are no newer invitations,
                 * the talkd works LIFO.)
                 */
                ctl_transact(his_machine_addr, msg, DELETE, rp);
                close(sockt);
                open_sockt();
                return (0);
        }
        p_error("Unable to connect with initiator");
        /*NOTREACHED*/
}

/*
 * Look for an invitation on 'machine'
 */
look_for_invite(rp)
        CTL_RESPONSE *rp;
{
        struct in_addr machine_addr;

        current_state = "Checking for invitation on caller's machine";
        ctl_transact(his_machine_addr, msg, LOOK_UP, rp);
        /* the switch is for later options, such as multiple invitations */
        switch (rp->answer) {

        case SUCCESS:
                msg.id_num = htonl(rp->id_num);
                return (1);

        default:
                /* there wasn't an invitation waiting for us */
                return (0);
        }
}