4.3BSD - /usr/src/etc/timed/candidate.c

   1: /*
   2:  * Copyright (c) 1983 Regents of the University of California.
   3:  * All rights reserved.  The Berkeley software License Agreement
   4:  * specifies the terms and conditions for redistribution.
   5:  */
   6: 
   7: #ifndef lint
   8: static char sccsid[] = "@(#)candidate.c	2.3 (Berkeley) 4/21/86";
   9: #endif not lint
  10: 
  11: #include "globals.h"
  12: #include <protocols/timed.h>
  13: 
  14: #define ELECTIONWAIT    3   /* seconds */
  15: 
  16: /*
  17:  * `election' candidates a host as master: it is called by a slave
  18:  * which runs with the -M option set when its election timeout expires.
  19:  * Note the conservative approach: if a new timed comes up, or another
  20:  * candidate sends an election request, the candidature is withdrawn.
  21:  */
  22: 
  23: election(net)
  24: struct netinfo *net;
  25: {
  26:     int ret;
  27:     struct tsp *resp, msg, *readmsg();
  28:     struct timeval wait;
  29:     struct tsp *answer, *acksend();
  30:     long casual();
  31:     struct sockaddr_in server;
  32: 
  33:     syslog(LOG_INFO, "THIS MACHINE IS A CANDIDATE");
  34:     if (trace) {
  35:         fprintf(fd, "THIS MACHINE IS A CANDIDATE\n");
  36:     }
  37: 
  38:     ret = MASTER;
  39:     slvcount = 1;
  40: 
  41:     msg.tsp_type = TSP_ELECTION;
  42:     msg.tsp_vers = TSPVERSION;
  43:     (void)strcpy(msg.tsp_name, hostname);
  44:     bytenetorder(&msg);
  45:     if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0, &net->dest_addr,
  46:         sizeof(struct sockaddr_in)) < 0) {
  47:         syslog(LOG_ERR, "sendto: %m");
  48:         exit(1);
  49:     }
  50: 
  51:     do {
  52:         wait.tv_sec = ELECTIONWAIT;
  53:         wait.tv_usec = 0;
  54:         resp = readmsg(TSP_ANY, (char *)ANYADDR, &wait, net);
  55:         if (resp != NULL) {
  56:             switch (resp->tsp_type) {
  57: 
  58:             case TSP_ACCEPT:
  59:                 (void) addmach(resp->tsp_name, &from);
  60:                 break;
  61: 
  62:             case TSP_MASTERUP:
  63:             case TSP_MASTERREQ:
  64:                 /*
  65: 				 * If a timedaemon is coming up at the same time,
  66: 				 * give up the candidature: it will be the master.
  67: 				 */
  68:                 ret = SLAVE;
  69:                 break;
  70: 
  71:             case TSP_QUIT:
  72:             case TSP_REFUSE:
  73:                 /*
  74: 				 * Collision: change value of election timer
  75: 				 * using exponential backoff.
  76: 				 * The value of timer will be recomputed (in slave.c)
  77: 				 * using the original interval when election will
  78: 				 * be successfully completed.
  79: 				 */
  80:                 backoff *= 2;
  81:                 delay2 = casual((long)MINTOUT,
  82:                             (long)(MAXTOUT * backoff));
  83:                 ret = SLAVE;
  84:                 break;
  85: 
  86:             case TSP_ELECTION:
  87:                 /* no master for another round */
  88:                 msg.tsp_type = TSP_REFUSE;
  89:                 (void)strcpy(msg.tsp_name, hostname);
  90:                 server = from;
  91:                 answer = acksend(&msg, &server, resp->tsp_name,
  92:                     TSP_ACK, (struct netinfo *)NULL);
  93:                 if (answer == NULL) {
  94:                     syslog(LOG_ERR, "error in election");
  95:                 } else {
  96:                     (void) addmach(resp->tsp_name, &from);
  97:                 }
  98:                 break;
  99: 
 100:             case TSP_SLAVEUP:
 101:                 (void) addmach(resp->tsp_name, &from);
 102:                 break;
 103: 
 104:             case TSP_SETDATE:
 105:             case TSP_SETDATEREQ:
 106:                 break;
 107: 
 108:             default:
 109:                 if (trace) {
 110:                     fprintf(fd, "candidate: ");
 111:                     print(resp, &from);
 112:                 }
 113:                 break;
 114:             }
 115:         } else {
 116:             break;
 117:         }
 118:     } while (ret == MASTER);
 119:     return(ret);
 120: }

Defined functions

Defined variables

Defined macros