acksend.c revision 50479 
1/*-
2 * Copyright (c) 1985, 1993
3 *	The Regents of the University of California.  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#if 0
36static char sccsid[] = "@(#)acksend.c	8.1 (Berkeley) 6/6/93";
37#endif
38static const char rcsid[] =
39  "$FreeBSD: head/usr.sbin/timed/timed/acksend.c 50479 1999-08-28 01:35:59Z peter $";
40#endif /* not lint */
41
42#include "globals.h"
43
44struct tsp *answer;
45
46extern u_short sequence;
47
48void
49xmit(type, seq, addr)
50	int type;
51	u_int seq;
52	struct sockaddr_in *addr;
53{
54	static struct tsp msg;
55
56	msg.tsp_type = type;
57	msg.tsp_seq = seq;
58	msg.tsp_vers = TSPVERSION;
59	(void)strcpy(msg.tsp_name, hostname);
60	bytenetorder(&msg);
61	if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0,
62		   (struct sockaddr*)addr, sizeof(struct sockaddr)) < 0) {
63		trace_sendto_err(addr->sin_addr);
64	}
65}
66
67
68/*
69 * Acksend implements reliable datagram transmission by using sequence
70 * numbers and retransmission when necessary.
71 * If `name' is ANYADDR, this routine implements reliable broadcast.
72 *
73 * Because this function calls readmsg(), none of its args may be in
74 *	a message provided by readmsg().
75 */
76struct tsp *
77acksend(message, addr, name, ack, net, bad)
78	struct tsp *message;			/* this message */
79	struct sockaddr_in *addr;		/* to here */
80	char *name;
81	int ack;				/* look for this ack */
82	struct netinfo *net;			/* receive from this network */
83	int bad;				/* 1=losing patience */
84{
85	struct timeval twait;
86	int count;
87	long msec;
88
89	message->tsp_vers = TSPVERSION;
90	message->tsp_seq = sequence;
91	if (trace) {
92		fprintf(fd, "acksend: to %s: ",
93			(name == ANYADDR ? "broadcast" : name));
94		print(message, addr);
95	}
96	bytenetorder(message);
97
98	msec = 200;
99	count = bad ? 1 : 5;	/* 5 packets in 6.4 seconds */
100	answer = 0;
101	do {
102		if (!answer) {
103			/* do not go crazy transmitting just because the
104			 * other guy cannot keep our sequence numbers
105			 * straight.
106			 */
107			if (sendto(sock, (char *)message, sizeof(struct tsp),
108				   0, (struct sockaddr*)addr,
109				   sizeof(struct sockaddr)) < 0) {
110				trace_sendto_err(addr->sin_addr);
111				break;
112			}
113		}
114
115		mstotvround(&twait, msec);
116		answer  = readmsg(ack, name, &twait, net);
117		if (answer != 0) {
118			if (answer->tsp_seq != sequence) {
119				if (trace)
120					fprintf(fd,"acksend: seq # %u!=%u\n",
121						answer->tsp_seq, sequence);
122				continue;
123			}
124			break;
125		}
126
127		msec *= 2;
128	} while (--count > 0);
129	sequence++;
130
131	return(answer);
132}
133