acksend.c revision 330897 
1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1985, 1993
5 *	The Regents of the University of California.  All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 * 4. Neither the name of the University nor the names of its contributors
16 *    may be used to endorse or promote products derived from this software
17 *    without specific prior written permission.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
20 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
21 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
22 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
23 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
24 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
25 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
26 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
27 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
28 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
29 * SUCH DAMAGE.
30 */
31
32#ifndef lint
33#if 0
34static char sccsid[] = "@(#)acksend.c	8.1 (Berkeley) 6/6/93";
35#endif
36static const char rcsid[] =
37  "$FreeBSD: stable/11/usr.sbin/timed/timed/acksend.c 330897 2018-03-14 03:19:51Z eadler $";
38#endif /* not lint */
39
40#include "globals.h"
41
42struct tsp *answer;
43
44extern u_short sequence;
45
46void
47xmit(int type, u_int seq, struct sockaddr_in *addr)
48{
49	static struct tsp msg;
50
51	msg.tsp_type = type;
52	msg.tsp_seq = seq;
53	msg.tsp_vers = TSPVERSION;
54	(void)strcpy(msg.tsp_name, hostname);
55	bytenetorder(&msg);
56	if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0,
57		   (struct sockaddr*)addr, sizeof(struct sockaddr)) < 0) {
58		trace_sendto_err(addr->sin_addr);
59	}
60}
61
62
63/*
64 * Acksend implements reliable datagram transmission by using sequence
65 * numbers and retransmission when necessary.
66 * If `name' is ANYADDR, this routine implements reliable broadcast.
67 *
68 * Because this function calls readmsg(), none of its args may be in
69 *	a message provided by readmsg().
70 * message		this message
71 * addr			to here
72 * ack			look for this ack
73 * net			receive from this network
74 * bad			1=losing patience
75 */
76struct tsp *
77acksend(struct tsp *message, struct sockaddr_in *addr, char *name,
78	int ack, struct netinfo *net, int bad)
79{
80	struct timeval twait;
81	int count;
82	long msec;
83
84	message->tsp_vers = TSPVERSION;
85	message->tsp_seq = sequence;
86	if (trace) {
87		fprintf(fd, "acksend: to %s: ",
88			(name == ANYADDR ? "broadcast" : name));
89		print(message, addr);
90	}
91	bytenetorder(message);
92
93	msec = 200;
94	count = bad ? 1 : 5;	/* 5 packets in 6.4 seconds */
95	answer = NULL;
96	do {
97		if (!answer) {
98			/* do not go crazy transmitting just because the
99			 * other guy cannot keep our sequence numbers
100			 * straight.
101			 */
102			if (sendto(sock, (char *)message, sizeof(struct tsp),
103				   0, (struct sockaddr*)addr,
104				   sizeof(struct sockaddr)) < 0) {
105				trace_sendto_err(addr->sin_addr);
106				break;
107			}
108		}
109
110		mstotvround(&twait, msec);
111		answer  = readmsg(ack, name, &twait, net);
112		if (answer != NULL) {
113			if (answer->tsp_seq != sequence) {
114				if (trace)
115					fprintf(fd,"acksend: seq # %u!=%u\n",
116						answer->tsp_seq, sequence);
117				continue;
118			}
119			break;
120		}
121
122		msec *= 2;
123	} while (--count > 0);
124	sequence++;
125
126	return(answer);
127}
128