/* * react to a TSP_QUIT: */ void doquit(struct tsp *msg) { if (fromnet->status == MASTER) { if (!good_host_name(msg->tsp_name)) { if (fromnet->quit_count <= 0) { syslog(LOG_NOTICE,"untrusted %s told us QUIT", msg->tsp_name); suppress(&from, msg->tsp_name, fromnet); fromnet->quit_count = 1; return; } syslog(LOG_NOTICE, "untrusted %s told us QUIT twice", msg->tsp_name); fromnet->quit_count = 2; fromnet->status = NOMASTER; } else { fromnet->status = SLAVE; } rmnetmachs(fromnet); longjmp(jmpenv, 2); /* give up and be a slave */ } else { if (!good_host_name(msg->tsp_name)) { syslog(LOG_NOTICE, "untrusted %s told us QUIT", msg->tsp_name); fromnet->quit_count = 2; } } }
int slave() { int tries; long electiontime, refusetime, looktime, looptime, adjtime; u_short seq; long fastelection; #define FASTTOUT 3 struct in_addr cadr; struct timeval otime; struct sockaddr_in taddr; char tname[MAXHOSTNAMELEN]; struct tsp *msg, to; struct timeval ntime, wait, tmptv; time_t tsp_time_sec; struct tsp *answer; int timeout(); char olddate[32]; char newdate[32]; struct netinfo *ntp; struct hosttbl *htp; struct utmpx utx; old_slavenet = 0; seq = 0; refusetime = 0; adjtime = 0; (void)gettimeofday(&ntime, NULL); electiontime = ntime.tv_sec + delay2; fastelection = ntime.tv_sec + FASTTOUT; if (justquit) looktime = electiontime; else looktime = fastelection; looptime = fastelection; if (slavenet) xmit(TSP_SLAVEUP, 0, &slavenet->dest_addr); if (status & MASTER) { for (ntp = nettab; ntp != NULL; ntp = ntp->next) { if (ntp->status == MASTER) masterup(ntp); } } loop: get_goodgroup(0); (void)gettimeofday(&ntime, NULL); if (ntime.tv_sec > electiontime) { if (trace) fprintf(fd, "election timer expired\n"); longjmp(jmpenv, 1); } if (ntime.tv_sec >= looktime) { if (trace) fprintf(fd, "Looking for nets to master\n"); if (Mflag && nignorednets > 0) { for (ntp = nettab; ntp != NULL; ntp = ntp->next) { if (ntp->status == IGNORE || ntp->status == NOMASTER) { lookformaster(ntp); if (ntp->status == MASTER) { masterup(ntp); } else if (ntp->status == MASTER) { ntp->status = NOMASTER; } } if (ntp->status == MASTER && --ntp->quit_count < 0) ntp->quit_count = 0; } makeslave(slavenet); /* prune extras */ setstatus(); } (void)gettimeofday(&ntime, NULL); looktime = ntime.tv_sec + delay2; } if (ntime.tv_sec >= looptime) { if (trace) fprintf(fd, "Looking for loops\n"); for (ntp = nettab; ntp != NULL; ntp = ntp->next) { if (ntp->status == MASTER) { to.tsp_type = TSP_LOOP; to.tsp_vers = TSPVERSION; to.tsp_seq = sequence++; to.tsp_hopcnt = MAX_HOPCNT; (void)strcpy(to.tsp_name, hostname); bytenetorder(&to); if (sendto(sock, (char *)&to, sizeof(struct tsp), 0, (struct sockaddr*)&ntp->dest_addr, sizeof(ntp->dest_addr)) < 0) { trace_sendto_err(ntp->dest_addr.sin_addr); } } } (void)gettimeofday(&ntime, NULL); looptime = ntime.tv_sec + delay2; } wait.tv_sec = min(electiontime,min(looktime,looptime)) - ntime.tv_sec; if (wait.tv_sec < 0) wait.tv_sec = 0; wait.tv_sec += FASTTOUT; wait.tv_usec = 0; msg = readmsg(TSP_ANY, ANYADDR, &wait, 0); if (msg != NULL) { /* * filter stuff not for us */ switch (msg->tsp_type) { case TSP_SETDATE: case TSP_TRACEOFF: case TSP_TRACEON: /* * XXX check to see they are from ourself */ break; case TSP_TEST: case TSP_MSITE: break; case TSP_MASTERUP: if (!fromnet) { if (trace) { fprintf(fd, "slave ignored: "); print(msg, &from); } goto loop; } break; default: if (!fromnet || fromnet->status == IGNORE || fromnet->status == NOMASTER) { if (trace) { fprintf(fd, "slave ignored: "); print(msg, &from); } goto loop; } break; } /* * now process the message */ switch (msg->tsp_type) { case TSP_ADJTIME: if (fromnet != slavenet) break; if (!good_host_name(msg->tsp_name)) { syslog(LOG_NOTICE, "attempted time adjustment by %s", msg->tsp_name); suppress(&from, msg->tsp_name, fromnet); break; } /* * Speed up loop detection in case we have a loop. * Otherwise the clocks can race until the loop * is found. */ (void)gettimeofday(&otime, NULL); if (adjtime < otime.tv_sec) looptime -= (looptime-otime.tv_sec)/2 + 1; setmaster(msg); if (seq != msg->tsp_seq) { seq = msg->tsp_seq; synch(tvtomsround(msg->tsp_time)); } (void)gettimeofday(&ntime, NULL); electiontime = ntime.tv_sec + delay2; fastelection = ntime.tv_sec + FASTTOUT; adjtime = ntime.tv_sec + SAMPLEINTVL*2; break; case TSP_SETTIME: if (fromnet != slavenet) break; if (seq == msg->tsp_seq) break; seq = msg->tsp_seq; /* adjust time for residence on the queue */ (void)gettimeofday(&otime, NULL); adj_msg_time(msg,&otime); /* * the following line is necessary due to syslog * calling ctime() which clobbers the static buffer */ (void)strcpy(olddate, date()); tsp_time_sec = msg->tsp_time.tv_sec; (void)strcpy(newdate, ctime(&tsp_time_sec)); if (!good_host_name(msg->tsp_name)) { syslog(LOG_NOTICE, "attempted time setting by untrusted %s to %s", msg->tsp_name, newdate); suppress(&from, msg->tsp_name, fromnet); break; } setmaster(msg); tmptv.tv_sec = msg->tsp_time.tv_sec; tmptv.tv_usec = msg->tsp_time.tv_usec; timevalsub(&ntime, &tmptv, &otime); if (ntime.tv_sec < MAXADJ && ntime.tv_sec > -MAXADJ) { /* * do not change the clock if we can adjust it */ synch(tvtomsround(ntime)); } else { utx.ut_type = OLD_TIME; gettimeofday(&utx.ut_tv, NULL); pututxline(&utx); (void)settimeofday(&tmptv, 0); utx.ut_type = NEW_TIME; gettimeofday(&utx.ut_tv, NULL); pututxline(&utx); syslog(LOG_NOTICE, "date changed by %s from %s", msg->tsp_name, olddate); if (status & MASTER) spreadtime(); } (void)gettimeofday(&ntime, NULL); electiontime = ntime.tv_sec + delay2; fastelection = ntime.tv_sec + FASTTOUT; /* This patches a bad protocol bug. Imagine a system with several networks, * where there are a pair of redundant gateways between a pair of networks, * each running timed. Assume that we start with a third machine mastering * one of the networks, and one of the gateways mastering the other. * Imagine that the third machine goes away and the non-master gateway * decides to replace it. If things are timed just 'right,' we will have * each gateway mastering one network for a little while. If a SETTIME * message gets into the network at that time, perhaps from the newly * masterful gateway as it was taking control, the SETTIME will loop * forever. Each time a gateway receives it on its slave side, it will * call spreadtime to forward it on its mastered network. We are now in * a permanent loop, since the SETTIME msgs will keep any clock * in the network from advancing. Normally, the 'LOOP' stuff will detect * and correct the situation. However, with the clocks stopped, the * 'looptime' timer cannot expire. While they are in this state, the * masters will try to saturate the network with SETTIME packets. */ looptime = ntime.tv_sec + (looptime-otime.tv_sec)/2-1; break; case TSP_MASTERUP: if (slavenet && fromnet != slavenet) break; if (!good_host_name(msg->tsp_name)) { suppress(&from, msg->tsp_name, fromnet); if (electiontime > fastelection) electiontime = fastelection; break; } makeslave(fromnet); setmaster(msg); setstatus(); answerdelay(); xmit(TSP_SLAVEUP, 0, &from); (void)gettimeofday(&ntime, NULL); electiontime = ntime.tv_sec + delay2; fastelection = ntime.tv_sec + FASTTOUT; refusetime = 0; break; case TSP_MASTERREQ: if (fromnet->status != SLAVE) break; (void)gettimeofday(&ntime, NULL); electiontime = ntime.tv_sec + delay2; break; case TSP_SETDATE: tsp_time_sec = msg->tsp_time.tv_sec; (void)strcpy(newdate, ctime(&tsp_time_sec)); schgdate(msg, newdate); break; case TSP_SETDATEREQ: if (fromnet->status != MASTER) break; tsp_time_sec = msg->tsp_time.tv_sec; (void)strcpy(newdate, ctime(&tsp_time_sec)); htp = findhost(msg->tsp_name); if (0 == htp) { syslog(LOG_WARNING, "DATEREQ from uncontrolled machine"); break; } if (!htp->good) { syslog(LOG_WARNING, "attempted date change by untrusted %s to %s", htp->name, newdate); spreadtime(); break; } schgdate(msg, newdate); break; case TSP_TRACEON: traceon(); break; case TSP_TRACEOFF: traceoff("Tracing ended at %s\n"); break; case TSP_SLAVEUP: newslave(msg); break; case TSP_ELECTION: if (fromnet->status == SLAVE) { (void)gettimeofday(&ntime, NULL); electiontime = ntime.tv_sec + delay2; fastelection = ntime.tv_sec + FASTTOUT; seq = 0; if (!good_host_name(msg->tsp_name)) { syslog(LOG_NOTICE, "suppress election of %s", msg->tsp_name); to.tsp_type = TSP_QUIT; electiontime = fastelection; } else if (cadr.s_addr != from.sin_addr.s_addr && ntime.tv_sec < refusetime) { /* if the candidate has to repeat itself, the old code would refuse it * the second time. That would prevent elections. */ to.tsp_type = TSP_REFUSE; } else { cadr.s_addr = from.sin_addr.s_addr; to.tsp_type = TSP_ACCEPT; refusetime = ntime.tv_sec + 30; } taddr = from; (void)strcpy(tname, msg->tsp_name); (void)strcpy(to.tsp_name, hostname); answerdelay(); if (!acksend(&to, &taddr, tname, TSP_ACK, 0, 0)) syslog(LOG_WARNING, "no answer from candidate %s\n", tname); } else { /* fromnet->status == MASTER */ htp = addmach(msg->tsp_name, &from,fromnet); to.tsp_type = TSP_QUIT; (void)strcpy(to.tsp_name, hostname); if (!acksend(&to, &htp->addr, htp->name, TSP_ACK, 0, htp->noanswer)) { syslog(LOG_ERR, "no reply from %s to ELECTION-QUIT", htp->name); (void)remmach(htp); } } break; case TSP_CONFLICT: if (fromnet->status != MASTER) break; /* * After a network partition, there can be * more than one master: the first slave to * come up will notify here the situation. */ (void)strcpy(to.tsp_name, hostname); /* The other master often gets into the same state, * with boring results. */ ntp = fromnet; /* (acksend() can leave fromnet=0 */ for (tries = 0; tries < 3; tries++) { to.tsp_type = TSP_RESOLVE; answer = acksend(&to, &ntp->dest_addr, ANYADDR, TSP_MASTERACK, ntp, 0); if (answer == NULL) break; htp = addmach(answer->tsp_name,&from,ntp); to.tsp_type = TSP_QUIT; answer = acksend(&to, &htp->addr, htp->name, TSP_ACK, 0, htp->noanswer); if (!answer) { syslog(LOG_WARNING, "conflict error: no reply from %s to QUIT", htp->name); (void)remmach(htp); } } masterup(ntp); break; case TSP_MSITE: if (!slavenet) break; taddr = from; to.tsp_type = TSP_MSITEREQ; to.tsp_vers = TSPVERSION; to.tsp_seq = 0; (void)strcpy(to.tsp_name, hostname); answer = acksend(&to, &slavenet->dest_addr, ANYADDR, TSP_ACK, slavenet, 0); if (answer != NULL && good_host_name(answer->tsp_name)) { setmaster(answer); to.tsp_type = TSP_ACK; (void)strcpy(to.tsp_name, answer->tsp_name); bytenetorder(&to); if (sendto(sock, (char *)&to, sizeof(struct tsp), 0, (struct sockaddr*)&taddr, sizeof(taddr)) < 0) { trace_sendto_err(taddr.sin_addr); } } break; case TSP_MSITEREQ: break; case TSP_ACCEPT: case TSP_REFUSE: case TSP_RESOLVE: break; case TSP_QUIT: doquit(msg); /* become a slave */ break; case TSP_TEST: electiontime = 0; break; case TSP_LOOP: /* looking for loops of masters */ if (!(status & MASTER)) break; if (fromnet->status == SLAVE) { if (!strcmp(msg->tsp_name, hostname)) { /* * Someone forwarded our message back to * us. There must be a loop. Tell the * master of this network to quit. * * The other master often gets into * the same state, with boring results. */ ntp = fromnet; for (tries = 0; tries < 3; tries++) { to.tsp_type = TSP_RESOLVE; answer = acksend(&to, &ntp->dest_addr, ANYADDR, TSP_MASTERACK, ntp,0); if (answer == NULL) break; taddr = from; (void)strcpy(tname, answer->tsp_name); to.tsp_type = TSP_QUIT; (void)strcpy(to.tsp_name, hostname); if (!acksend(&to, &taddr, tname, TSP_ACK, 0, 1)) { syslog(LOG_ERR, "no reply from %s to slave LOOP-QUIT", tname); } else { electiontime = 0; } } (void)gettimeofday(&ntime, NULL); looptime = ntime.tv_sec + FASTTOUT; } else { if (msg->tsp_hopcnt-- < 1) break; bytenetorder(msg); for (ntp = nettab; ntp != 0; ntp = ntp->next) { if (ntp->status == MASTER && 0 > sendto(sock, (char *)msg, sizeof(struct tsp), 0, (struct sockaddr*)&ntp->dest_addr, sizeof(ntp->dest_addr))) trace_sendto_err(ntp->dest_addr.sin_addr); } } } else { /* fromnet->status == MASTER */ /* * We should not have received this from a net * we are master on. There must be two masters, * unless the packet was really from us. */ if (from.sin_addr.s_addr == fromnet->my_addr.s_addr) { if (trace) fprintf(fd,"discarding forwarded LOOP\n"); break; } /* * The other master often gets into the same * state, with boring results. */ ntp = fromnet; for (tries = 0; tries < 3; tries++) { to.tsp_type = TSP_RESOLVE; answer = acksend(&to, &ntp->dest_addr, ANYADDR, TSP_MASTERACK, ntp,0); if (!answer) break; htp = addmach(answer->tsp_name, &from,ntp); to.tsp_type = TSP_QUIT; (void)strcpy(to.tsp_name, hostname); if (!acksend(&to,&htp->addr,htp->name, TSP_ACK, 0, htp->noanswer)) { syslog(LOG_ERR, "no reply from %s to master LOOP-QUIT", htp->name); (void)remmach(htp); } } (void)gettimeofday(&ntime, NULL); looptime = ntime.tv_sec + FASTTOUT; } break; default: if (trace) { fprintf(fd, "garbage message: "); print(msg, &from); } break; } } goto loop; }
/* * The main function of `master' is to periodically compute the differences * (deltas) between its clock and the clocks of the slaves, to compute the * network average delta, and to send to the slaves the differences between * their individual deltas and the network delta. * While waiting, it receives messages from the slaves (i.e. requests for * master's name, remote requests to set the network time, ...), and * takes the appropriate action. */ int master() { struct hosttbl *htp; long pollingtime; #define POLLRATE 4 int polls; struct timeval wait, ntime; time_t tsp_time_sec; struct tsp *msg, *answer, to; char newdate[32]; struct sockaddr_in taddr; char tname[MAXHOSTNAMELEN]; struct netinfo *ntp; int i; syslog(LOG_NOTICE, "This machine is master"); if (trace) fprintf(fd, "This machine is master\n"); for (ntp = nettab; ntp != NULL; ntp = ntp->next) { if (ntp->status == MASTER) masterup(ntp); } (void)gettimeofday(&ntime, 0); pollingtime = ntime.tv_sec+3; if (justquit) polls = 0; else polls = POLLRATE-1; /* Process all outstanding messages before spending the long time necessary * to update all timers. */ loop: (void)gettimeofday(&ntime, 0); wait.tv_sec = pollingtime - ntime.tv_sec; if (wait.tv_sec < 0) wait.tv_sec = 0; wait.tv_usec = 0; msg = readmsg(TSP_ANY, ANYADDR, &wait, 0); if (!msg) { (void)gettimeofday(&ntime, 0); if (ntime.tv_sec >= pollingtime) { pollingtime = ntime.tv_sec + SAMPLEINTVL; get_goodgroup(0); /* If a bogus master told us to quit, we can have decided to ignore a * network. Therefore, periodically try to take over everything. */ polls = (polls + 1) % POLLRATE; if (0 == polls && nignorednets > 0) { trace_msg("Looking for nets to re-master\n"); for (ntp = nettab; ntp; ntp = ntp->next) { if (ntp->status == IGNORE || ntp->status == NOMASTER) { lookformaster(ntp); if (ntp->status == MASTER) { masterup(ntp); polls = POLLRATE-1; } } if (ntp->status == MASTER && --ntp->quit_count < 0) ntp->quit_count = 0; } if (polls != 0) setstatus(); } synch(0L); for (ntp = nettab; ntp != NULL; ntp = ntp->next) { to.tsp_type = TSP_LOOP; to.tsp_vers = TSPVERSION; to.tsp_seq = sequence++; to.tsp_hopcnt = MAX_HOPCNT; (void)strcpy(to.tsp_name, hostname); bytenetorder(&to); if (sendto(sock, (char *)&to, sizeof(struct tsp), 0, (struct sockaddr*)&ntp->dest_addr, sizeof(ntp->dest_addr)) < 0) { trace_sendto_err(ntp->dest_addr.sin_addr); } } } } else { switch (msg->tsp_type) { case TSP_MASTERREQ: break; case TSP_SLAVEUP: newslave(msg); break; case TSP_SETDATE: /* * XXX check to see it is from ourself */ tsp_time_sec = msg->tsp_time.tv_sec; (void)strcpy(newdate, ctime(&tsp_time_sec)); if (!good_host_name(msg->tsp_name)) { syslog(LOG_NOTICE, "attempted date change by %s to %s", msg->tsp_name, newdate); spreadtime(); break; } mchgdate(msg); (void)gettimeofday(&ntime, 0); pollingtime = ntime.tv_sec + SAMPLEINTVL; break; case TSP_SETDATEREQ: if (!fromnet || fromnet->status != MASTER) break; tsp_time_sec = msg->tsp_time.tv_sec; (void)strcpy(newdate, ctime(&tsp_time_sec)); htp = findhost(msg->tsp_name); if (htp == 0) { syslog(LOG_ERR, "attempted SET DATEREQ by uncontrolled %s to %s", msg->tsp_name, newdate); break; } if (htp->seq == msg->tsp_seq) break; htp->seq = msg->tsp_seq; if (!htp->good) { syslog(LOG_NOTICE, "attempted SET DATEREQ by untrusted %s to %s", msg->tsp_name, newdate); spreadtime(); break; } mchgdate(msg); (void)gettimeofday(&ntime, 0); pollingtime = ntime.tv_sec + SAMPLEINTVL; break; case TSP_MSITE: xmit(TSP_ACK, msg->tsp_seq, &from); break; case TSP_MSITEREQ: break; case TSP_TRACEON: traceon(); break; case TSP_TRACEOFF: traceoff("Tracing ended at %s\n"); break; case TSP_ELECTION: if (!fromnet) break; if (fromnet->status == MASTER) { pollingtime = 0; (void)addmach(msg->tsp_name, &from,fromnet); } taddr = from; (void)strcpy(tname, msg->tsp_name); to.tsp_type = TSP_QUIT; (void)strcpy(to.tsp_name, hostname); answer = acksend(&to, &taddr, tname, TSP_ACK, 0, 1); if (answer == NULL) { syslog(LOG_ERR, "election error by %s", tname); } break; case TSP_CONFLICT: /* * After a network partition, there can be * more than one master: the first slave to * come up will notify here the situation. */ if (!fromnet || fromnet->status != MASTER) break; (void)strcpy(to.tsp_name, hostname); /* The other master often gets into the same state, * with boring results if we stay at it forever. */ ntp = fromnet; /* (acksend() can leave fromnet=0 */ for (i = 0; i < 3; i++) { to.tsp_type = TSP_RESOLVE; (void)strcpy(to.tsp_name, hostname); answer = acksend(&to, &ntp->dest_addr, ANYADDR, TSP_MASTERACK, ntp, 0); if (!answer) break; htp = addmach(answer->tsp_name,&from,ntp); to.tsp_type = TSP_QUIT; msg = acksend(&to, &htp->addr, htp->name, TSP_ACK, 0, htp->noanswer); if (msg == NULL) { syslog(LOG_ERR, "no response from %s to CONFLICT-QUIT", htp->name); } } masterup(ntp); pollingtime = 0; break; case TSP_RESOLVE: if (!fromnet || fromnet->status != MASTER) break; /* * do not want to call synch() while waiting * to be killed! */ (void)gettimeofday(&ntime, (struct timezone *)0); pollingtime = ntime.tv_sec + SAMPLEINTVL; break; case TSP_QUIT: doquit(msg); /* become a slave */ break; case TSP_LOOP: if (!fromnet || fromnet->status != MASTER || !strcmp(msg->tsp_name, hostname)) break; /* * We should not have received this from a net * we are master on. There must be two masters. */ htp = addmach(msg->tsp_name, &from,fromnet); to.tsp_type = TSP_QUIT; (void)strcpy(to.tsp_name, hostname); answer = acksend(&to, &htp->addr, htp->name, TSP_ACK, 0, 1); if (!answer) { syslog(LOG_WARNING, "loop breakage: no reply from %s=%s to QUIT", htp->name, inet_ntoa(htp->addr.sin_addr)); (void)remmach(htp); } case TSP_TEST: if (trace) { fprintf(fd, "\tnets = %d, masters = %d, slaves = %d, ignored = %d\n", nnets, nmasternets, nslavenets, nignorednets); setstatus(); } pollingtime = 0; polls = POLLRATE-1; break; default: if (trace) { fprintf(fd, "garbage message: "); print(msg, &from); } break; } } goto loop; }
/* update our image of the net-group of trustworthy hosts */ void get_goodgroup(int force) { # define NG_DELAY (30*60*CLK_TCK) /* 30 minutes */ static unsigned long last_update = -NG_DELAY; unsigned long new_update; struct goodhost *ghp, **ghpp; #ifdef HAVENIS struct hosttbl *htp; char *mach, *usr, *dom; #endif /* HAVENIS */ struct tms tm; /* if no netgroup, then we are finished */ if (goodgroup == NULL || !Mflag) return; /* Do not chatter with the netgroup master too often. */ new_update = times(&tm); if (new_update < last_update + NG_DELAY && !force) return; last_update = new_update; /* forget the old temporary entries */ ghpp = &goodhosts; while ((ghp = *ghpp) != NULL) { if (!ghp->perm) { *ghpp = ghp->next; free(ghp); } else { ghpp = &ghp->next; } } #ifdef HAVENIS /* quit now if we are not one of the trusted masters */ if (!innetgr(goodgroup, &hostname[0], 0,0)) { if (trace) (void)fprintf(fd, "get_goodgroup: %s not in %s\n", &hostname[0], goodgroup); return; } if (trace) (void)fprintf(fd, "get_goodgroup: %s in %s\n", &hostname[0], goodgroup); /* mark the entire netgroup as trusted */ (void)setnetgrent(goodgroup); while (getnetgrent(&mach,&usr,&dom)) { if (mach != NULL) add_good_host(mach,0); } (void)endnetgrent(); /* update list of slaves */ for (htp = self.l_fwd; htp != &self; htp = htp->l_fwd) { htp->good = good_host_name(&htp->name[0]); } #endif /* HAVENIS */ }
void lookformaster(struct netinfo *ntp) { struct tsp resp, conflict, *answer; struct timeval ntime; char mastername[MAXHOSTNAMELEN]; struct sockaddr_in masteraddr; get_goodgroup(0); ntp->status = SLAVE; /* look for master */ resp.tsp_type = TSP_MASTERREQ; (void)strcpy(resp.tsp_name, hostname); answer = acksend(&resp, &ntp->dest_addr, ANYADDR, TSP_MASTERACK, ntp, 0); if (answer != NULL && !good_host_name(answer->tsp_name)) { suppress(&from, answer->tsp_name, ntp); ntp->status = NOMASTER; answer = NULL; } if (answer == NULL) { /* * Various conditions can cause conflict: races between * two just started timedaemons when no master is * present, or timedaemons started during an election. * A conservative approach is taken. Give up and became a * slave, postponing election of a master until first * timer expires. */ ntime.tv_sec = ntime.tv_usec = 0; answer = readmsg(TSP_MASTERREQ, ANYADDR, &ntime, ntp); if (answer != NULL) { if (!good_host_name(answer->tsp_name)) { suppress(&from, answer->tsp_name, ntp); ntp->status = NOMASTER; } return; } ntime.tv_sec = ntime.tv_usec = 0; answer = readmsg(TSP_MASTERUP, ANYADDR, &ntime, ntp); if (answer != NULL) { if (!good_host_name(answer->tsp_name)) { suppress(&from, answer->tsp_name, ntp); ntp->status = NOMASTER; } return; } ntime.tv_sec = ntime.tv_usec = 0; answer = readmsg(TSP_ELECTION, ANYADDR, &ntime, ntp); if (answer != NULL) { if (!good_host_name(answer->tsp_name)) { suppress(&from, answer->tsp_name, ntp); ntp->status = NOMASTER; } return; } if (Mflag) ntp->status = MASTER; else ntp->status = NOMASTER; return; } ntp->status = SLAVE; (void)strcpy(mastername, answer->tsp_name); masteraddr = from; /* * If network has been partitioned, there might be other * masters; tell the one we have just acknowledged that * it has to gain control over the others. */ ntime.tv_sec = 0; ntime.tv_usec = 300000; answer = readmsg(TSP_MASTERACK, ANYADDR, &ntime, ntp); /* * checking also not to send CONFLICT to ack'ed master * due to duplicated MASTERACKs */ if (answer != NULL && strcmp(answer->tsp_name, mastername) != 0) { conflict.tsp_type = TSP_CONFLICT; (void)strcpy(conflict.tsp_name, hostname); if (!acksend(&conflict, &masteraddr, mastername, TSP_ACK, 0, 0)) { syslog(LOG_ERR, "error on sending TSP_CONFLICT"); } } }
/* * add a host to the list of controlled machines if not already there */ struct hosttbl * addmach(char *name, struct sockaddr_in *addr, struct netinfo *ntp) { struct hosttbl *ret, *p, *b, *f; ret = findhost(name); if (ret == 0) { if (slvcount >= NHOSTS) { if (trace) { fprintf(fd, "no more slots in host table\n"); prthp(CLK_TCK); } syslog(LOG_ERR, "no more slots in host table"); Mflag = 0; longjmp(jmpenv, 2); /* give up and be a slave */ } /* if our home hash slot is occupied, find a free entry * in the hash table */ if (newhost_hash->name[0] != '\0') { do { ret = lasthfree; if (++lasthfree > &hosttbl[NHOSTS]) lasthfree = &hosttbl[1]; } while (ret->name[0] != '\0'); if (!newhost_hash->head) { /* Move an interloper using our home. Use * scratch pointers in case the new head is * pointing to itself. */ f = newhost_hash->h_fwd; b = newhost_hash->h_bak; f->h_bak = ret; b->h_fwd = ret; f = newhost_hash->l_fwd; b = newhost_hash->l_bak; f->l_bak = ret; b->l_fwd = ret; bcopy(newhost_hash,ret,sizeof(*ret)); ret = newhost_hash; ret->head = 1; ret->h_fwd = ret; ret->h_bak = ret; } else { /* link to an existing chain in our home */ ret->head = 0; p = newhost_hash->h_bak; ret->h_fwd = newhost_hash; ret->h_bak = p; p->h_fwd = ret; newhost_hash->h_bak = ret; } } else { ret = newhost_hash; ret->head = 1; ret->h_fwd = ret; ret->h_bak = ret; } ret->addr = *addr; ret->ntp = ntp; (void)strncpy(ret->name, name, sizeof(ret->name)); ret->good = good_host_name(name); ret->l_fwd = &self; ret->l_bak = self.l_bak; self.l_bak->l_fwd = ret; self.l_bak = ret; slvcount++; ret->noanswer = 0; ret->need_set = 1; } else { ret->noanswer = (ret->noanswer != 0); } /* need to clear sequence number anyhow */ ret->seq = 0; return(ret); }
/* * `election' candidates a host as master: it is called by a slave * which runs with the -M option set when its election timeout expires. * Note the conservative approach: if a new timed comes up, or another * candidate sends an election request, the candidature is withdrawn. */ int election(struct netinfo *net) { struct tsp *resp, msg; struct timeval then, wait; struct tsp *answer; struct hosttbl *htp; char loop_lim = 0; /* This code can get totally confused if it gets slightly behind. For * example, if readmsg() has some QUIT messages waiting from the last * round, we would send an ELECTION message, get the stale QUIT, * and give up. This results in network storms when several machines * do it at once. */ wait.tv_sec = 0; wait.tv_usec = 0; while (0 != readmsg(TSP_REFUSE, ANYADDR, &wait, net)) { if (trace) fprintf(fd, "election: discarded stale REFUSE\n"); } while (0 != readmsg(TSP_QUIT, ANYADDR, &wait, net)) { if (trace) fprintf(fd, "election: discarded stale QUIT\n"); } again: syslog(LOG_INFO, "This machine is a candidate time master"); if (trace) fprintf(fd, "This machine is a candidate time master\n"); msg.tsp_type = TSP_ELECTION; msg.tsp_vers = TSPVERSION; (void)strcpy(msg.tsp_name, hostname); bytenetorder(&msg); if (sendto(sock, (char *)&msg, sizeof(struct tsp), 0, (struct sockaddr*)&net->dest_addr, sizeof(struct sockaddr)) < 0) { trace_sendto_err(net->dest_addr.sin_addr); return(SLAVE); } (void)gettimeofday(&then, 0); then.tv_sec += 3; for (;;) { (void)gettimeofday(&wait, 0); timevalsub(&wait,&then,&wait); resp = readmsg(TSP_ANY, ANYADDR, &wait, net); if (!resp) return(MASTER); switch (resp->tsp_type) { case TSP_ACCEPT: (void)addmach(resp->tsp_name, &from,fromnet); break; case TSP_MASTERUP: case TSP_MASTERREQ: /* * If another timedaemon is coming up at the same * time, give up, and let it be the master. */ if (++loop_lim < 5 && !good_host_name(resp->tsp_name)) { (void)addmach(resp->tsp_name, &from,fromnet); suppress(&from, resp->tsp_name, net); goto again; } rmnetmachs(net); return(SLAVE); case TSP_QUIT: case TSP_REFUSE: /* * Collision: change value of election timer * using exponential backoff. * * Fooey. * An exponential backoff on a delay starting at * 6 to 15 minutes for a process that takes * milliseconds is silly. It is particularly * strange that the original code would increase * the backoff without bound. */ rmnetmachs(net); return(SLAVE); case TSP_ELECTION: /* no master for another round */ htp = addmach(resp->tsp_name,&from,fromnet); msg.tsp_type = TSP_REFUSE; (void)strcpy(msg.tsp_name, hostname); answer = acksend(&msg, &htp->addr, htp->name, TSP_ACK, 0, htp->noanswer); if (!answer) { syslog(LOG_ERR, "error in election from %s", htp->name); } break; case TSP_SLAVEUP: (void)addmach(resp->tsp_name, &from,fromnet); break; case TSP_SETDATE: case TSP_SETDATEREQ: break; default: if (trace) { fprintf(fd, "candidate: "); print(resp, &from); } break; } } }