4.3BSD-Reno/src/usr.bin/talk/ctl_transact.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: (1) source distributions retain this entire copyright
 * notice and comment, and (2) distributions including binaries display
 * the following acknowledgement:  ``This product includes software
 * developed by the University of California, Berkeley and its contributors''
 * in the documentation or other materials provided with the distribution
 * and in all advertising materials mentioning features or use of this
 * software. Neither the name of the University nor the names of its
 * contributors may be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#ifndef lint
static char sccsid[] = "@(#)ctl_transact.c	5.7 (Berkeley) 6/1/90";
#endif /* not lint */

#include "talk_ctl.h"
#include <sys/time.h>

#define CTL_WAIT 2	/* time to wait for a response, in seconds */

/*
 * SOCKDGRAM is unreliable, so we must repeat messages if we have
 * not recieved an acknowledgement within a reasonable amount
 * of time
 */
ctl_transact(target, msg, type, rp)
	struct in_addr target;
	CTL_MSG msg;
	int type;
	CTL_RESPONSE *rp;
{
	int read_mask, ctl_mask, nready, cc;
	struct timeval wait;

	msg.type = type;
	daemon_addr.sin_addr = target;
	daemon_addr.sin_port = daemon_port;
	ctl_mask = 1 << ctl_sockt;

	/*
	 * Keep sending the message until a response of
	 * the proper type is obtained.
	 */
	do {
		wait.tv_sec = CTL_WAIT;
		wait.tv_usec = 0;
		/* resend message until a response is obtained */
		do {
			cc = sendto(ctl_sockt, (char *)&msg, sizeof (msg), 0,
				&daemon_addr, sizeof (daemon_addr));
			if (cc != sizeof (msg)) {
				if (errno == EINTR)
					continue;
				p_error("Error on write to talk daemon");
			}
			read_mask = ctl_mask;
			nready = select(32, &read_mask, 0, 0, &wait);
			if (nready < 0) {
				if (errno == EINTR)
					continue;
				p_error("Error waiting for daemon response");
			}
		} while (nready == 0);
		/*
		 * Keep reading while there are queued messages 
		 * (this is not necessary, it just saves extra
		 * request/acknowledgements being sent)
		 */
		do {
			cc = recv(ctl_sockt, (char *)rp, sizeof (*rp), 0);
			if (cc < 0) {
				if (errno == EINTR)
					continue;
				p_error("Error on read from talk daemon");
			}
			read_mask = ctl_mask;
			/* an immediate poll */
			timerclear(&wait);
			nready = select(32, &read_mask, 0, 0, &wait);
		} while (nready > 0 && (rp->vers != TALK_VERSION ||
		    rp->type != type));
	} while (rp->vers != TALK_VERSION || rp->type != type);
	rp->id_num = ntohl(rp->id_num);
	rp->addr.sa_family = ntohs(rp->addr.sa_family);
}