acksend.c revision 30642 
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	"$Id$";
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)strncpy(msg.tsp_name, hostname, sizeof msg.tsp_name-1);
60	msg.tsp_name[sizeof msg.tsp_name-1] = '\0';
61	bytenetorder(&msg);
62	if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0,
63		   (struct sockaddr*)addr, sizeof(struct sockaddr)) < 0) {
64		trace_sendto_err(addr->sin_addr);
65	}
66}
67
68
69/*
70 * Acksend implements reliable datagram transmission by using sequence
71 * numbers and retransmission when necessary.
72 * If `name' is ANYADDR, this routine implements reliable broadcast.
73 *
74 * Because this function calls readmsg(), none of its args may be in
75 *	a message provided by readmsg().
76 */
77struct tsp *
78acksend(message, addr, name, ack, net, bad)
79	struct tsp *message;			/* this message */
80	struct sockaddr_in *addr;		/* to here */
81	char *name;
82	int ack;				/* look for this ack */
83	struct netinfo *net;			/* receive from this network */
84	int bad;				/* 1=losing patience */
85{
86	struct timeval twait;
87	int count;
88	long msec;
89
90	message->tsp_vers = TSPVERSION;
91	message->tsp_seq = sequence;
92	if (trace) {
93		fprintf(fd, "acksend: to %s: ",
94			(name == ANYADDR ? "broadcast" : name));
95		print(message, addr);
96	}
97	bytenetorder(message);
98
99	msec = 200;
100	count = bad ? 1 : 5;	/* 5 packets in 6.4 seconds */
101	answer = 0;
102	do {
103		if (!answer) {
104			/* do not go crazy transmitting just because the
105			 * other guy cannot keep our sequence numbers
106			 * straight.
107			 */
108			if (sendto(sock, (char *)message, sizeof(struct tsp),
109				   0, (struct sockaddr*)addr,
110				   sizeof(struct sockaddr)) < 0) {
111				trace_sendto_err(addr->sin_addr);
112				break;
113			}
114		}
115
116		mstotvround(&twait, msec);
117		answer  = readmsg(ack, name, &twait, net);
118		if (answer != 0) {
119			if (answer->tsp_seq != sequence) {
120				if (trace)
121					fprintf(fd,"acksend: seq # %u!=%u\n",
122						answer->tsp_seq, sequence);
123				continue;
124			}
125			break;
126		}
127
128		msec *= 2;
129	} while (--count > 0);
130	sequence++;
131
132	return(answer);
133}
134