timed.tproj/timed.tproj/candidate.c

   1 /*
   2  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * "Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
   7  * Reserved.  This file contains Original Code and/or Modifications of
   8  * Original Code as defined in and that are subject to the Apple Public
   9  * Source License Version 1.0 (the 'License').  You may not use this file
  10  * except in compliance with the License.  Please obtain a copy of the
  11  * License at http://www.apple.com/publicsource and read it before using
  12  * this file.
  13  *
  14  * The Original Code and all software distributed under the License are
  15  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  19  * License for the specific language governing rights and limitations
  20  * under the License."
  21  *
  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  24 /*-
  25  * Copyright (c) 1985, 1993
  26  *      The Regents of the University of California.  All rights reserved.
  27  *
  28  * Redistribution and use in source and binary forms, with or without
  29  * modification, are permitted provided that the following conditions
  30  * are met:
  31  * 1. Redistributions of source code must retain the above copyright
  32  *    notice, this list of conditions and the following disclaimer.
  33  * 2. Redistributions in binary form must reproduce the above copyright
  34  *    notice, this list of conditions and the following disclaimer in the
  35  *    documentation and/or other materials provided with the distribution.
  36  * 3. All advertising materials mentioning features or use of this software
  37  *    must display the following acknowledgement:
  38  *      This product includes software developed by the University of
  39  *      California, Berkeley and its contributors.
  40  * 4. Neither the name of the University nor the names of its contributors
  41  *    may be used to endorse or promote products derived from this software
  42  *    without specific prior written permission.
  43  *
  44  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  45  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  46  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  47  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  48  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  49  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  50  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  51  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  52  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  53  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  54  * SUCH DAMAGE.
  55  */
  56
  57 #ifndef lint
  58 static char sccsid[] = "@(#)candidate.c 8.1 (Berkeley) 6/6/93";
  59 #endif /* not lint */
  60
  61 #ifdef sgi
  62 #ident "$Revision: 1.1.1.1 $"
  63 #endif
  64
  65 #include "globals.h"
  66
  67 /*
  68  * `election' candidates a host as master: it is called by a slave
  69  * which runs with the -M option set when its election timeout expires.
  70  * Note the conservative approach: if a new timed comes up, or another
  71  * candidate sends an election request, the candidature is withdrawn.
  72  */
  73 int
  74 election(net)
  75         struct netinfo *net;
  76 {
  77         struct tsp *resp, msg;
  78         struct timeval then, wait;
  79         struct tsp *answer;
  80         struct hosttbl *htp;
  81         char loop_lim = 0;
  82
  83 /* This code can get totally confused if it gets slightly behind.  For
  84  *      example, if readmsg() has some QUIT messages waiting from the last
  85  *      round, we would send an ELECTION message, get the stale QUIT,
  86  *      and give up.  This results in network storms when several machines
  87  *      do it at once.
  88  */
  89         wait.tv_sec = 0;
  90         wait.tv_usec = 0;
  91         while (0 != readmsg(TSP_REFUSE, ANYADDR, &wait, net)) {
  92                 if (trace)
  93                         fprintf(fd, "election: discarded stale REFUSE\n");
  94         }
  95         while (0 != readmsg(TSP_QUIT, ANYADDR, &wait, net)) {
  96                 if (trace)
  97                         fprintf(fd, "election: discarded stale QUIT\n");
  98         }
  99
 100 again:
 101         syslog(LOG_INFO, "This machine is a candidate time master");
 102         if (trace)
 103                 fprintf(fd, "This machine is a candidate time master\n");
 104         msg.tsp_type = TSP_ELECTION;
 105         msg.tsp_vers = TSPVERSION;
 106         (void)strcpy(msg.tsp_name, hostname);
 107         bytenetorder(&msg);
 108         if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0,
 109                    (struct sockaddr*)&net->dest_addr,
 110                    sizeof(struct sockaddr)) < 0) {
 111                 trace_sendto_err(net->dest_addr.sin_addr);
 112                 return(SLAVE);
 113         }
 114
 115         (void)gettimeofday(&then, 0);
 116         then.tv_sec += 3;
 117         for (;;) {
 118                 (void)gettimeofday(&wait, 0);
 119                 timevalsub(&wait,&then,&wait);
 120                 resp = readmsg(TSP_ANY, ANYADDR, &wait, net);
 121                 if (!resp)
 122                         return(MASTER);
 123
 124                 switch (resp->tsp_type) {
 125
 126                 case TSP_ACCEPT:
 127                         (void)addmach(resp->tsp_name, &from,fromnet);
 128                         break;
 129
 130                 case TSP_MASTERUP:
 131                 case TSP_MASTERREQ:
 132                         /*
 133                          * If another timedaemon is coming up at the same
 134                          * time, give up, and let it be the master.
 135                          */
 136                         if (++loop_lim < 5
 137                             && !good_host_name(resp->tsp_name)) {
 138                                 (void)addmach(resp->tsp_name, &from,fromnet);
 139                                 suppress(&from, resp->tsp_name, net);
 140                                 goto again;
 141                         }
 142                         rmnetmachs(net);
 143                         return(SLAVE);
 144
 145                 case TSP_QUIT:
 146                 case TSP_REFUSE:
 147                         /*
 148                          * Collision: change value of election timer
 149                          * using exponential backoff.
 150                          *
 151                          *  Fooey.
 152                          * An exponential backoff on a delay starting at
 153                          * 6 to 15 minutes for a process that takes
 154                          * milliseconds is silly.  It is particularly
 155                          * strange that the original code would increase
 156                          * the backoff without bound.
 157                          */
 158                         rmnetmachs(net);
 159                         return(SLAVE);
 160
 161                 case TSP_ELECTION:
 162                         /* no master for another round */
 163                         htp = addmach(resp->tsp_name,&from,fromnet);
 164                         msg.tsp_type = TSP_REFUSE;
 165                         (void)strcpy(msg.tsp_name, hostname);
 166                         answer = acksend(&msg, &htp->addr, htp->name,
 167                                          TSP_ACK, 0, htp->noanswer);
 168                         if (!answer) {
 169                                 syslog(LOG_ERR, "error in election from %s",
 170                                        htp->name);
 171                         }
 172                         break;
 173
 174                 case TSP_SLAVEUP:
 175                         (void)addmach(resp->tsp_name, &from,fromnet);
 176                         break;
 177
 178                 case TSP_SETDATE:
 179                 case TSP_SETDATEREQ:
 180                         break;
 181
 182                 default:
 183                         if (trace) {
 184                                 fprintf(fd, "candidate: ");
 185                                 print(resp, &from);
 186                         }
 187                         break;
 188                 }
 189         }
 190 }