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look_up.c revision 1.2 
      1 /*
      2  * Copyright (c) 1983 Regents of the University of California.
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  * 3. All advertising materials mentioning features or use of this software
     14  *    must display the following acknowledgement:
     15  *	This product includes software developed by the University of
     16  *	California, Berkeley and its contributors.
     17  * 4. Neither the name of the University nor the names of its contributors
     18  *    may be used to endorse or promote products derived from this software
     19  *    without specific prior written permission.
     20  *
     21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     31  * SUCH DAMAGE.
     32  */
     33 
     34 #ifndef lint
     35 /*static char sccsid[] = "from: @(#)look_up.c	5.7 (Berkeley) 3/1/91";*/
     36 static char rcsid[] = "$Id: look_up.c,v 1.2 1993/08/01 18:07:47 mycroft Exp $";
     37 #endif /* not lint */
     38 
     39 #include <sys/types.h>
     40 #include <sys/socket.h>
     41 #include <netinet/in.h>
     42 #include <protocols/talkd.h>
     43 #include <errno.h>
     44 #include "talk_ctl.h"
     45 #include "talk.h"
     46 
     47 /*
     48  * See if the local daemon has an invitation for us.
     49  */
     50 check_local()
     51 {
     52 	CTL_RESPONSE response;
     53 	register CTL_RESPONSE *rp = &response;
     54 
     55 	/* the rest of msg was set up in get_names */
     56 #ifdef MSG_EOR
     57 	/* copy new style sockaddr to old, swap family (short in old) */
     58 	msg.ctl_addr = *(struct osockaddr *)&ctl_addr;
     59 	msg.ctl_addr.sa_family = htons(ctl_addr.sin_family);
     60 #else
     61 	msg.ctl_addr = *(struct sockaddr *)&ctl_addr;
     62 #endif
     63 	/* must be initiating a talk */
     64 	if (!look_for_invite(rp))
     65 		return (0);
     66 	/*
     67 	 * There was an invitation waiting for us,
     68 	 * so connect with the other (hopefully waiting) party
     69 	 */
     70 	current_state = "Waiting to connect with caller";
     71 	do {
     72 		if (rp->addr.sa_family != AF_INET)
     73 			p_error("Response uses invalid network address");
     74 		errno = 0;
     75 		if (connect(sockt,
     76 		    (struct sockaddr *)&rp->addr, sizeof (rp->addr)) != -1)
     77 			return (1);
     78 	} while (errno == EINTR);
     79 	if (errno == ECONNREFUSED) {
     80 		/*
     81 		 * The caller gave up, but his invitation somehow
     82 		 * was not cleared. Clear it and initiate an
     83 		 * invitation. (We know there are no newer invitations,
     84 		 * the talkd works LIFO.)
     85 		 */
     86 		ctl_transact(his_machine_addr, msg, DELETE, rp);
     87 		close(sockt);
     88 		open_sockt();
     89 		return (0);
     90 	}
     91 	p_error("Unable to connect with initiator");
     92 	/*NOTREACHED*/
     93 }
     94 
     95 /*
     96  * Look for an invitation on 'machine'
     97  */
     98 look_for_invite(rp)
     99 	CTL_RESPONSE *rp;
    100 {
    101 	struct in_addr machine_addr;
    102 
    103 	current_state = "Checking for invitation on caller's machine";
    104 	ctl_transact(his_machine_addr, msg, LOOK_UP, rp);
    105 	/* the switch is for later options, such as multiple invitations */
    106 	switch (rp->answer) {
    107 
    108 	case SUCCESS:
    109 		msg.id_num = htonl(rp->id_num);
    110 		return (1);
    111 
    112 	default:
    113 		/* there wasn't an invitation waiting for us */
    114 		return (0);
    115 	}
    116 }
    117