usr.sbin/timed/timed/candidate.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  * @(#)candidate.c      8.1 (Berkeley) 6/6/93
  34  * $FreeBSD: src/usr.sbin/timed/timed/candidate.c,v 1.5 1999/08/28 01:20:16 peter Exp $
  35  * $DragonFly: src/usr.sbin/timed/timed/candidate.c,v 1.5 2004/09/05 02:20:15 dillon Exp $
  36  */
  37
  38 #include "globals.h"
  39
  40 /*
  41  * `election' candidates a host as master: it is called by a slave
  42  * which runs with the -M option set when its election timeout expires.
  43  * Note the conservative approach: if a new timed comes up, or another
  44  * candidate sends an election request, the candidature is withdrawn.
  45  */
  46 int
  47 election(struct netinfo *net)
  48 {
  49         struct tsp *resp, msg;
  50         struct timeval then, wait;
  51         struct tsp *answer;
  52         struct hosttbl *htp;
  53         char loop_lim = 0;
  54
  55 /* This code can get totally confused if it gets slightly behind.  For
  56  *      example, if readmsg() has some QUIT messages waiting from the last
  57  *      round, we would send an ELECTION message, get the stale QUIT,
  58  *      and give up.  This results in network storms when several machines
  59  *      do it at once.
  60  */
  61         wait.tv_sec = 0;
  62         wait.tv_usec = 0;
  63         while (0 != readmsg(TSP_REFUSE, ANYADDR, &wait, net)) {
  64                 if (trace)
  65                         fprintf(fd, "election: discarded stale REFUSE\n");
  66         }
  67         while (0 != readmsg(TSP_QUIT, ANYADDR, &wait, net)) {
  68                 if (trace)
  69                         fprintf(fd, "election: discarded stale QUIT\n");
  70         }
  71
  72 again:
  73         syslog(LOG_INFO, "This machine is a candidate time master");
  74         if (trace)
  75                 fprintf(fd, "This machine is a candidate time master\n");
  76         msg.tsp_type = TSP_ELECTION;
  77         msg.tsp_vers = TSPVERSION;
  78         strlcpy(msg.tsp_name, hostname, sizeof(msg.tsp_name));
  79         bytenetorder(&msg);
  80         if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0,
  81                    (struct sockaddr*)&net->dest_addr,
  82                    sizeof(struct sockaddr)) < 0) {
  83                 trace_sendto_err(net->dest_addr.sin_addr);
  84                 return(SLAVE);
  85         }
  86
  87         gettimeofday(&then, 0);
  88         then.tv_sec += 3;
  89         for (;;) {
  90                 gettimeofday(&wait, 0);
  91                 timevalsub(&wait,&then,&wait);
  92                 resp = readmsg(TSP_ANY, ANYADDR, &wait, net);
  93                 if (!resp)
  94                         return(MASTER);
  95
  96                 switch (resp->tsp_type) {
  97
  98                 case TSP_ACCEPT:
  99                         addmach(resp->tsp_name, &from,fromnet);
 100                         break;
 101
 102                 case TSP_MASTERUP:
 103                 case TSP_MASTERREQ:
 104                         /*
 105                          * If another timedaemon is coming up at the same
 106                          * time, give up, and let it be the master.
 107                          */
 108                         if (++loop_lim < 5
 109                             && !good_host_name(resp->tsp_name)) {
 110                                 addmach(resp->tsp_name, &from,fromnet);
 111                                 suppress(&from, resp->tsp_name, net);
 112                                 goto again;
 113                         }
 114                         rmnetmachs(net);
 115                         return(SLAVE);
 116
 117                 case TSP_QUIT:
 118                 case TSP_REFUSE:
 119                         /*
 120                          * Collision: change value of election timer
 121                          * using exponential backoff.
 122                          *
 123                          *  Fooey.
 124                          * An exponential backoff on a delay starting at
 125                          * 6 to 15 minutes for a process that takes
 126                          * milliseconds is silly.  It is particularly
 127                          * strange that the original code would increase
 128                          * the backoff without bound.
 129                          */
 130                         rmnetmachs(net);
 131                         return(SLAVE);
 132
 133                 case TSP_ELECTION:
 134                         /* no master for another round */
 135                         htp = addmach(resp->tsp_name,&from,fromnet);
 136                         msg.tsp_type = TSP_REFUSE;
 137                         strlcpy(msg.tsp_name, hostname, sizeof(msg.tsp_name));
 138                         answer = acksend(&msg, &htp->addr, htp->name,
 139                                          TSP_ACK, 0, htp->noanswer);
 140                         if (!answer) {
 141                                 syslog(LOG_ERR, "error in election from %s",
 142                                        htp->name);
 143                         }
 144                         break;
 145
 146                 case TSP_SLAVEUP:
 147                         addmach(resp->tsp_name, &from,fromnet);
 148                         break;
 149
 150                 case TSP_SETDATE:
 151                 case TSP_SETDATEREQ:
 152                         break;
 153
 154                 default:
 155                         if (trace) {
 156                                 fprintf(fd, "candidate: ");
 157                                 print(resp, &from);
 158                         }
 159                         break;
 160                 }
 161         }
 162 }