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      1 /*	$NetBSD: acksend.c,v 1.11 2007/01/26 16:12:41 christos Exp $	*/
      2 
      3 /*-
      4  * Copyright (c) 1985, 1993 The Regents of the University of California.
      5  * 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  * 3. 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 #include <sys/cdefs.h>
     33 #ifndef lint
     34 #if 0
     35 static char sccsid[] = "@(#)acksend.c	8.1 (Berkeley) 6/6/93";
     36 #else
     37 __RCSID("$NetBSD: acksend.c,v 1.11 2007/01/26 16:12:41 christos Exp $");
     38 #endif
     39 #endif /* not lint */
     40 
     41 #include "globals.h"
     42 
     43 
     44 struct tsp *answer;
     45 
     46 extern u_short sequence;
     47 
     48 void
     49 xmit(int type, u_short seq, struct sockaddr_in *addr)
     50 {
     51 	static struct tsp msg;
     52 
     53 	msg.tsp_type = type;
     54 	msg.tsp_seq = seq;
     55 	msg.tsp_vers = TSPVERSION;
     56 
     57 	set_tsp_name(&msg, hostname);
     58 	bytenetorder(&msg);
     59 	(void)sendtsp(sock, &msg, addr);
     60 }
     61 
     62 int
     63 sendtsp(int s, struct tsp *msg, struct sockaddr_in *addr)
     64 {
     65 	int error;
     66 
     67 	error = sendto(s, msg, sizeof(*msg), 0,
     68 	    (struct sockaddr *)(void *)addr, sizeof(*addr));
     69 	if (error == -1)
     70 		trace_sendto_err(addr->sin_addr);
     71 	return error;
     72 }
     73 
     74 
     75 /*
     76  * Acksend implements reliable datagram transmission by using sequence
     77  * numbers and retransmission when necessary.
     78  * If `name' is ANYADDR, this routine implements reliable broadcast.
     79  *
     80  * Because this function calls readmsg(), none of its args may be in
     81  *	a message provided by readmsg().
     82  */
     83 struct tsp *
     84 acksend(struct tsp *message,		/* this message */
     85 	struct sockaddr_in *addr, char *name,	/* to here */
     86 	int ack,			/* look for this ack */
     87 	struct netinfo *net,		/* receive from this network */
     88 	int bad)			/* 1=losing patience */
     89 {
     90 	struct timeval twait;
     91 	int count;
     92 	long msec;
     93 
     94 	message->tsp_vers = TSPVERSION;
     95 	message->tsp_seq = sequence;
     96 	if (trace) {
     97 		fprintf(fd, "acksend: to %s: ",
     98 			(name == ANYADDR ? "broadcast" : name));
     99 		print(message, addr);
    100 	}
    101 	bytenetorder(message);
    102 
    103 	msec = 200;
    104 	count = bad ? 1 : 5;	/* 5 packets in 6.4 seconds */
    105 	answer = 0;
    106 	do {
    107 		if (!answer) {
    108 			/* do not go crazy transmitting just because the
    109 			 * other guy cannot keep our sequence numbers
    110 			 * straight.
    111 			 */
    112 			if (sendtsp(sock, message, addr) == -1)
    113 				break;
    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