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  * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
   7  *
   8  * This file contains Original Code and/or Modifications of Original Code
   9  * as defined in and that are subject to the Apple Public Source License
  10  * Version 2.0 (the 'License'). You may not use this file except in
  11  * compliance with the License. Please obtain a copy of the License at
  12  * http://www.opensource.apple.com/apsl/ and read it before using this
  13  * file.
  14  *
  15  * The Original Code and all software distributed under the License are
  16  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  17  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  18  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  19  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  20  * Please see the License for the specific language governing rights and
  21  * limitations under the License.
  22  *
  23  * @APPLE_LICENSE_HEADER_END@
  24  */
  25 /*-
  26  * Copyright (c) 1985, 1993
  27  *      The Regents of the University of California.  All rights reserved.
  28  *
  29  * Redistribution and use in source and binary forms, with or without
  30  * modification, are permitted provided that the following conditions
  31  * are met:
  32  * 1. Redistributions of source code must retain the above copyright
  33  *    notice, this list of conditions and the following disclaimer.
  34  * 2. Redistributions in binary form must reproduce the above copyright
  35  *    notice, this list of conditions and the following disclaimer in the
  36  *    documentation and/or other materials provided with the distribution.
  37  * 3. All advertising materials mentioning features or use of this software
  38  *    must display the following acknowledgement:
  39  *      This product includes software developed by the University of
  40  *      California, Berkeley and its contributors.
  41  * 4. Neither the name of the University nor the names of its contributors
  42  *    may be used to endorse or promote products derived from this software
  43  *    without specific prior written permission.
  44  *
  45  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  46  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  47  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  48  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  49  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  50  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  51  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  52  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  53  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  54  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  55  * SUCH DAMAGE.
  56  */
  57
  58 #ifndef lint
  59 static char sccsid[] = "@(#)candidate.c 8.1 (Berkeley) 6/6/93";
  60 #endif /* not lint */
  61
  62 #ifdef sgi
  63 #ident "$Revision: 1.1.1.1 $"
  64 #endif
  65
  66 #include "globals.h"
  67
  68 /*
  69  * `election' candidates a host as master: it is called by a slave
  70  * which runs with the -M option set when its election timeout expires.
  71  * Note the conservative approach: if a new timed comes up, or another
  72  * candidate sends an election request, the candidature is withdrawn.
  73  */
  74 int
  75 election(net)
  76         struct netinfo *net;
  77 {
  78         struct tsp *resp, msg;
  79         struct timeval then, wait;
  80         struct tsp *answer;
  81         struct hosttbl *htp;
  82         char loop_lim = 0;
  83
  84 /* This code can get totally confused if it gets slightly behind.  For
  85  *      example, if readmsg() has some QUIT messages waiting from the last
  86  *      round, we would send an ELECTION message, get the stale QUIT,
  87  *      and give up.  This results in network storms when several machines
  88  *      do it at once.
  89  */
  90         wait.tv_sec = 0;
  91         wait.tv_usec = 0;
  92         while (0 != readmsg(TSP_REFUSE, ANYADDR, &wait, net)) {
  93                 if (trace)
  94                         fprintf(fd, "election: discarded stale REFUSE\n");
  95         }
  96         while (0 != readmsg(TSP_QUIT, ANYADDR, &wait, net)) {
  97                 if (trace)
  98                         fprintf(fd, "election: discarded stale QUIT\n");
  99         }
 100
 101 again:
 102         syslog(LOG_INFO, "This machine is a candidate time master");
 103         if (trace)
 104                 fprintf(fd, "This machine is a candidate time master\n");
 105         msg.tsp_type = TSP_ELECTION;
 106         msg.tsp_vers = TSPVERSION;
 107         (void)strcpy(msg.tsp_name, hostname);
 108         bytenetorder(&msg);
 109         if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0,
 110                    (struct sockaddr*)&net->dest_addr,
 111                    sizeof(struct sockaddr)) < 0) {
 112                 trace_sendto_err(net->dest_addr.sin_addr);
 113                 return(SLAVE);
 114         }
 115
 116         (void)gettimeofday(&then, 0);
 117         then.tv_sec += 3;
 118         for (;;) {
 119                 (void)gettimeofday(&wait, 0);
 120                 timevalsub(&wait,&then,&wait);
 121                 resp = readmsg(TSP_ANY, ANYADDR, &wait, net);
 122                 if (!resp)
 123                         return(MASTER);
 124
 125                 switch (resp->tsp_type) {
 126
 127                 case TSP_ACCEPT:
 128                         (void)addmach(resp->tsp_name, &from,fromnet);
 129                         break;
 130
 131                 case TSP_MASTERUP:
 132                 case TSP_MASTERREQ:
 133                         /*
 134                          * If another timedaemon is coming up at the same
 135                          * time, give up, and let it be the master.
 136                          */
 137                         if (++loop_lim < 5
 138                             && !good_host_name(resp->tsp_name)) {
 139                                 (void)addmach(resp->tsp_name, &from,fromnet);
 140                                 suppress(&from, resp->tsp_name, net);
 141                                 goto again;
 142                         }
 143                         rmnetmachs(net);
 144                         return(SLAVE);
 145
 146                 case TSP_QUIT:
 147                 case TSP_REFUSE:
 148                         /*
 149                          * Collision: change value of election timer
 150                          * using exponential backoff.
 151                          *
 152                          *  Fooey.
 153                          * An exponential backoff on a delay starting at
 154                          * 6 to 15 minutes for a process that takes
 155                          * milliseconds is silly.  It is particularly
 156                          * strange that the original code would increase
 157                          * the backoff without bound.
 158                          */
 159                         rmnetmachs(net);
 160                         return(SLAVE);
 161
 162                 case TSP_ELECTION:
 163                         /* no master for another round */
 164                         htp = addmach(resp->tsp_name,&from,fromnet);
 165                         msg.tsp_type = TSP_REFUSE;
 166                         (void)strcpy(msg.tsp_name, hostname);
 167                         answer = acksend(&msg, &htp->addr, htp->name,
 168                                          TSP_ACK, 0, htp->noanswer);
 169                         if (!answer) {
 170                                 syslog(LOG_ERR, "error in election from %s",
 171                                        htp->name);
 172                         }
 173                         break;
 174
 175                 case TSP_SLAVEUP:
 176                         (void)addmach(resp->tsp_name, &from,fromnet);
 177                         break;
 178
 179                 case TSP_SETDATE:
 180                 case TSP_SETDATEREQ:
 181                         break;
 182
 183                 default:
 184                         if (trace) {
 185                                 fprintf(fd, "candidate: ");
 186                                 print(resp, &from);
 187                         }
 188                         break;
 189                 }
 190         }
 191 }