acksend.c revision 216372 
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 * 4. Neither the name of the University nor the names of its contributors
14 *    may be used to endorse or promote products derived from this software
15 *    without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#ifndef lint
31#if 0
32static char sccsid[] = "@(#)acksend.c	8.1 (Berkeley) 6/6/93";
33#endif
34static const char rcsid[] =
35  "$FreeBSD: head/usr.sbin/timed/timed/acksend.c 216372 2010-12-11 09:38:12Z joel $";
36#endif /* not lint */
37
38#include "globals.h"
39
40struct tsp *answer;
41
42extern u_short sequence;
43
44void
45xmit(type, seq, addr)
46	int type;
47	u_int seq;
48	struct sockaddr_in *addr;
49{
50	static struct tsp msg;
51
52	msg.tsp_type = type;
53	msg.tsp_seq = seq;
54	msg.tsp_vers = TSPVERSION;
55	(void)strcpy(msg.tsp_name, hostname);
56	bytenetorder(&msg);
57	if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0,
58		   (struct sockaddr*)addr, sizeof(struct sockaddr)) < 0) {
59		trace_sendto_err(addr->sin_addr);
60	}
61}
62
63
64/*
65 * Acksend implements reliable datagram transmission by using sequence
66 * numbers and retransmission when necessary.
67 * If `name' is ANYADDR, this routine implements reliable broadcast.
68 *
69 * Because this function calls readmsg(), none of its args may be in
70 *	a message provided by readmsg().
71 */
72struct tsp *
73acksend(message, addr, name, ack, net, bad)
74	struct tsp *message;			/* this message */
75	struct sockaddr_in *addr;		/* to here */
76	char *name;
77	int ack;				/* look for this ack */
78	struct netinfo *net;			/* receive from this network */
79	int bad;				/* 1=losing patience */
80{
81	struct timeval twait;
82	int count;
83	long msec;
84
85	message->tsp_vers = TSPVERSION;
86	message->tsp_seq = sequence;
87	if (trace) {
88		fprintf(fd, "acksend: to %s: ",
89			(name == ANYADDR ? "broadcast" : name));
90		print(message, addr);
91	}
92	bytenetorder(message);
93
94	msec = 200;
95	count = bad ? 1 : 5;	/* 5 packets in 6.4 seconds */
96	answer = 0;
97	do {
98		if (!answer) {
99			/* do not go crazy transmitting just because the
100			 * other guy cannot keep our sequence numbers
101			 * straight.
102			 */
103			if (sendto(sock, (char *)message, sizeof(struct tsp),
104				   0, (struct sockaddr*)addr,
105				   sizeof(struct sockaddr)) < 0) {
106				trace_sendto_err(addr->sin_addr);
107				break;
108			}
109		}
110
111		mstotvround(&twait, msec);
112		answer  = readmsg(ack, name, &twait, net);
113		if (answer != 0) {
114			if (answer->tsp_seq != sequence) {
115				if (trace)
116					fprintf(fd,"acksend: seq # %u!=%u\n",
117						answer->tsp_seq, sequence);
118				continue;
119			}
120			break;
121		}
122
123		msec *= 2;
124	} while (--count > 0);
125	sequence++;
126
127	return(answer);
128}
129