usr.sbin/timed/timed/acksend.c

   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  * @(#)acksend.c        8.1 (Berkeley) 6/6/93
  34  * $FreeBSD: src/usr.sbin/timed/timed/acksend.c,v 1.4 1999/08/28 01:20:16 peter Exp $
  35  * $DragonFly: src/usr.sbin/timed/timed/acksend.c,v 1.4 2004/09/05 01:59:44 dillon Exp $
  36  */
  37
  38 #include "globals.h"
  39
  40 struct tsp *answer;
  41
  42 extern u_short sequence;
  43
  44 void
  45 xmit(int type, u_int seq, struct sockaddr_in *addr)
  46 {
  47         static struct tsp msg;
  48
  49         msg.tsp_type = type;
  50         msg.tsp_seq = seq;
  51         msg.tsp_vers = TSPVERSION;
  52         strlcpy(msg.tsp_name, hostname, sizeof(msg.tsp_name));
  53         bytenetorder(&msg);
  54         if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0,
  55                    (struct sockaddr*)addr, sizeof(struct sockaddr)) < 0) {
  56                 trace_sendto_err(addr->sin_addr);
  57         }
  58 }
  59
  60
  61 /*
  62  * Acksend implements reliable datagram transmission by using sequence
  63  * numbers and retransmission when necessary.
  64  * If `name' is ANYADDR, this routine implements reliable broadcast.
  65  *
  66  * Because this function calls readmsg(), none of its args may be in
  67  *      a message provided by readmsg().
  68  */
  69 struct tsp *
  70 acksend(struct tsp *message,            /* this message */
  71         struct sockaddr_in *addr,       /* to here */
  72         char *name,
  73         int ack,                        /* look for this ack */
  74         struct netinfo *net,            /* receive from this network */
  75         int bad)                        /* 1=losing patience */
  76 {
  77         struct timeval twait;
  78         int count;
  79         long msec;
  80
  81         message->tsp_vers = TSPVERSION;
  82         message->tsp_seq = sequence;
  83         if (trace) {
  84                 fprintf(fd, "acksend: to %s: ",
  85                         (name == ANYADDR ? "broadcast" : name));
  86                 print(message, addr);
  87         }
  88         bytenetorder(message);
  89
  90         msec = 200;
  91         count = bad ? 1 : 5;    /* 5 packets in 6.4 seconds */
  92         answer = 0;
  93         do {
  94                 if (!answer) {
  95                         /* do not go crazy transmitting just because the
  96                          * other guy cannot keep our sequence numbers
  97                          * straight.
  98                          */
  99                         if (sendto(sock, (char *)message, sizeof(struct tsp),
 100                                    0, (struct sockaddr*)addr,
 101                                    sizeof(struct sockaddr)) < 0) {
 102                                 trace_sendto_err(addr->sin_addr);
 103                                 break;
 104                         }
 105                 }
 106
 107                 mstotvround(&twait, msec);
 108                 answer  = readmsg(ack, name, &twait, net);
 109                 if (answer != 0) {
 110                         if (answer->tsp_seq != sequence) {
 111                                 if (trace)
 112                                         fprintf(fd,"acksend: seq # %u!=%u\n",
 113                                                 answer->tsp_seq, sequence);
 114                                 continue;
 115                         }
 116                         break;
 117                 }
 118
 119                 msec *= 2;
 120         } while (--count > 0);
 121         sequence++;
 122
 123         return(answer);
 124 }