/*
 * Copyright 2000, International Business Machines Corporation and others.
 * All Rights Reserved.
 * 
 * This software has been released under the terms of the IBM Public
 * License.  For details, see the LICENSE file in the top-level source
 * directory or online at http://www.openafs.org/dl/license10.html
 */

#include <afs/param.h>
#include <sys/types.h>
#ifdef AFS_NT40_ENV
#include <winsock2.h>
#include <time.h>
#else
#include <sys/file.h>
#include <netinet/in.h>
#include <sys/time.h>
#endif
#include <assert.h>
#include <lock.h>
#include <rx/xdr.h>
#include <rx/rx.h>
#include <errno.h>

#define UBIK_INTERNALS
#include "ubik.h"
#include "ubik_int.h"

/* This module is responsible for determining when the system has
 * recovered to the point that it can handle new transactions.  It
 * replays logs, polls to determine the current dbase after a crash,
 * and distributes the new database to the others.
 */

/* The sync site associates a version number with each database.  It
 * broadcasts the version associated with its current dbase in every
 * one of its beacon messages.  When the sync site send a dbase to a
 * server, it also sends the db's version.  A non-sync site server can
 * tell if it has the right dbase version by simply comparing the
 * version from the beacon message (uvote_dbVersion) with the version
 * associated with the database (ubik_dbase->version).  The sync site
 * itself simply has one counter to keep track of all of this (again
 * ubik_dbase->version).
 */

/* sync site: routine called when the sync site loses its quorum; this
 * procedure is called "up" from the beacon package.  It resyncs the
 * dbase and nudges the recovery daemon to try to propagate out the
 * changes.  It also resets the recovery daemon's state, since
 * recovery must potentially find a new dbase to propagate out.  This
 * routine should not do anything with variables used by non-sync site
 * servers.
 */ 

/* if this flag is set, then ubik will use only the primary address 
** ( the address specified in the CellServDB) to contact other 
** ubik servers. Ubik recovery will not try opening connections 
** to the alternate interface addresses. 
*/
int ubikPrimaryAddrOnly;

urecovery_ResetState() {
    urecovery_state = 0;
    LWP_NoYieldSignal(&urecovery_state);
    return 0;
}

/* sync site: routine called when a non-sync site server goes down; restarts recovery
 * process to send missing server the new db when it comes back up.
 * This routine should not do anything with variables used by non-sync site servers. 
 */
urecovery_LostServer() {
    LWP_NoYieldSignal(&urecovery_state);
    return 0;
}

/* return true iff we have a current database (called by both sync
 * sites and non-sync sites) How do we determine this?  If we're the
 * sync site, we wait until recovery has finished fetching and
 * re-labelling its dbase (it may still be trying to propagate it out
 * to everyone else; that's THEIR problem).  If we're not the sync
 * site, then we must have a dbase labelled with the right version,
 * and we must have a currently-good sync site.
 */
urecovery_AllBetter(adbase, areadAny)
    int areadAny;
    register struct ubik_dbase *adbase; {
    register afs_int32 rcode;

    ubik_dprint("allbetter checking\n");
    rcode = 0;
    
    
    if (areadAny) {
      if (ubik_dbase->version.epoch > 1)
	  rcode = 1;		          /* Happy with any good version of database */
    }

    /* Check if we're sync site and we've got the right data */
    else if (ubeacon_AmSyncSite() && (urecovery_state & UBIK_RECHAVEDB)) {
	rcode = 1;
    }

    /* next, check if we're aux site, and we've ever been sent the
     * right data (note that if a dbase update fails, we won't think
     * that the sync site is still the sync site, 'cause it won't talk
     * to us until a timeout period has gone by.  When we recover, we
     * leave this clear until we get a new dbase */
    else if ( (uvote_GetSyncSite() &&
	      (vcmp(ubik_dbVersion, ubik_dbase->version) == 0)) ) { /* && order is important */
	rcode = 1;
    }

    ubik_dprint("allbetter: returning %d\n", rcode);
    return rcode;
}

/* abort all transactions on this database */
urecovery_AbortAll(adbase)
struct ubik_dbase *adbase; {
    register struct ubik_trans *tt;
    for(tt = adbase->activeTrans; tt; tt=tt->next) {
	udisk_abort(tt);
    }
    return 0;
}

/* this routine aborts the current remote transaction, if any, if the tid is wrong */
urecovery_CheckTid(atid)
    register struct ubik_tid *atid; {
    if (ubik_currentTrans) {
	/* there is remote write trans, see if we match, see if this
         * is a new transaction */
	if (atid->epoch != ubik_currentTrans->tid.epoch || atid->counter > ubik_currentTrans->tid.counter) {
	    /* don't match, abort it */
	    /* If the thread is not waiting for lock - ok to end it */
	    if (ubik_currentTrans->locktype != LOCKWAIT) {
	       udisk_end(ubik_currentTrans);
	    }
	    ubik_currentTrans = (struct ubik_trans *) 0;
	}
    }
}

/* log format is defined here, and implicitly in disk.c
 *
 * 4 byte opcode, followed by parameters, each 4 bytes long.  All integers
 * are in logged in network standard byte order, in case we want to move logs
 * from machine-to-machine someday.
 *
 * Begin transaction: opcode
 * Commit transaction: opcode, version (8 bytes)
 * Truncate file: opcode, file number, length
 * Abort transaction: opcode
 * Write data: opcode, file, position, length, <length> data bytes
 *
 * A very simple routine, it just replays the log.  Note that this is a new-value only log, which
 * implies that no uncommitted data is written to the dbase: one writes data to the log, including
 * the commit record, then we allow data to be written through to the dbase.  In our particular
 * implementation, once a transaction is done, we write out the pages to the database, so that
 * our buffer package doesn't have to know about stable and uncommitted data in the memory buffers:
 * any changed data while there is an uncommitted write transaction can be zapped during an
 * abort and the remaining dbase on the disk is exactly the right dbase, without having to read
 * the log.
 */

/* replay logs */
static ReplayLog(adbase)
    register struct ubik_dbase *adbase; {
    afs_int32 opcode;
    register afs_int32 code, tpos;
    int logIsGood;
    afs_int32 len, thisSize, tfile, filePos;
    afs_int32 buffer[4];
    afs_int32 syncFile = -1;
    afs_int32 data[1024];

    /* read the lock twice, once to see whether we have a transaction to deal
	with that committed, (theoretically, we should support more than one
	trans in the log at once, but not yet), and once replaying the
	transactions.  */
    tpos = 0;
    logIsGood = 0;
    /* for now, assume that all ops in log pertain to one transaction; see if there's a commit */
    while (1) {
	code = (*adbase->read)(adbase, LOGFILE, &opcode, tpos, sizeof(afs_int32));
	if (code != sizeof(afs_int32)) break;
	if (opcode == LOGNEW) {
	    /* handle begin trans */
	    tpos += sizeof(afs_int32);
	}
	else if (opcode == LOGABORT) break;
	else if (opcode == LOGEND) {
	    logIsGood = 1;
	    break;
	}
	else if (opcode == LOGTRUNCATE) {
	    tpos += 4;
	    code = (*adbase->read)(adbase, LOGFILE, buffer, tpos, 2*sizeof(afs_int32));
	    if (code !=	2*sizeof(afs_int32))	break;	/* premature eof or io error */
	    tpos += 2*sizeof(afs_int32);
	}
	else if (opcode == LOGDATA) {
	    tpos += 4;
	    code = (*adbase->read)(adbase, LOGFILE, buffer, tpos, 3*sizeof(afs_int32));
	    if (code != 3*sizeof(afs_int32)) break;
	    /* otherwise, skip over the data bytes, too */
	    tpos += buffer[2] + 3*sizeof(afs_int32);
	}
	else {
	    ubik_dprint("corrupt log opcode (%d) at position %d\n", opcode, tpos);
	    break;	/* corrupt log! */
	}
    }
    if (logIsGood) {
	/* actually do the replay; log should go all the way through the commit record, since
	    we just read it above. */
	tpos = 0;
	logIsGood = 0;
	syncFile = -1;
	while (1) {
	    code = (*adbase->read)(adbase, LOGFILE, &opcode, tpos, sizeof(afs_int32));
	    if (code != sizeof(afs_int32)) break;
	    if (opcode == LOGNEW) {
		/* handle begin trans */
		tpos += sizeof(afs_int32);
	    }
	    else if (opcode == LOGABORT) panic("log abort\n");
	    else if (opcode == LOGEND) {
		tpos += 4;
		code = (*adbase->read) (adbase, LOGFILE, buffer, tpos, 2*sizeof(afs_int32));
		if (code != 2*sizeof(afs_int32)) return UBADLOG;
		code = (*adbase->setlabel) (adbase, 0, buffer);
		if (code) return code;
		logIsGood = 1;
		break;	    /* all done now */
	    }
	    else if (opcode == LOGTRUNCATE) {
		tpos += 4;
		code = (*adbase->read)(adbase, LOGFILE, buffer, tpos, 2*sizeof(afs_int32));
		if (code != 2*sizeof(afs_int32)) break;	/* premature eof or io error */
		tpos += 2*sizeof(afs_int32);
		code = (*adbase->truncate) (adbase, ntohl(buffer[0]), ntohl(buffer[1]));
		if (code) return code;
	    }
	    else if (opcode == LOGDATA) {
		tpos += 4;
		code = (*adbase->read)(adbase, LOGFILE, buffer, tpos, 3*sizeof(afs_int32));
		if (code != 3*sizeof(afs_int32)) break;
		tpos += 3*sizeof(afs_int32);
		/* otherwise, skip over the data bytes, too */
		len = ntohl(buffer[2]);	    /* total number of bytes to copy */
		filePos = ntohl(buffer[1]);
		tfile = ntohl(buffer[0]);
		/* try to minimize file syncs */
		if (syncFile != tfile) {
		    if (syncFile >= 0) code = (*adbase->sync)(adbase, syncFile);
		    else code = 0;
		    syncFile = tfile;
		    if (code) return code;
		}
		while (len > 0) {
		    thisSize = (len > sizeof(data)? sizeof(data) : len);
		    /* copy sizeof(data) buffer bytes at a time */
		    code = (*adbase->read)(adbase, LOGFILE, data, tpos, thisSize);
		    if (code != thisSize) return UBADLOG;
		    code = (*adbase->write)(adbase, tfile, data, filePos, thisSize);
		    if (code != thisSize) return UBADLOG;
		    filePos += thisSize;
		    tpos += thisSize;
		    len -= thisSize;
		}
	    }
	    else {
		ubik_dprint("corrupt log opcode (%d) at position %d\n", opcode, tpos);
		break;	/* corrupt log! */
	    }
	}
	if (logIsGood) {
	    if (syncFile >= 0) code = (*adbase->sync)(adbase, syncFile);
	    if (code) return code;
	}
	else {
	    ubik_dprint("Log read error on pass 2\n");
	    return UBADLOG;
	}
    }

    /* now truncate the log, we're done with it */
    code = (*adbase->truncate)(adbase, LOGFILE, 0);
    return code;
}

/* Called at initialization to figure out version of the dbase we really have.
 * This routine is called after replaying the log; it reads the restored labels.
 */
static InitializeDB(adbase)
    register struct ubik_dbase *adbase; {
    register afs_int32 code;
    
    code = (*adbase->getlabel)(adbase, 0, &adbase->version);
    if (code) {
	/* try setting the label to a new value */
	adbase->version.epoch =	1;	/* value for newly-initialized db */
	adbase->version.counter = 1;
	code = (*adbase->setlabel) (adbase, 0, &adbase->version);
	if (code) {
	    /* failed, try to set it back */
	    adbase->version.epoch = 0;
	    adbase->version.counter = 0;
	    (*adbase->setlabel) (adbase, 0, &adbase->version);
	}
	LWP_NoYieldSignal(&adbase->version);
    }
    return 0;
}

/* initialize the local dbase
 * We replay the logs and then read the resulting file to figure out what version we've really got.
 */
urecovery_Initialize(adbase)
    register struct ubik_dbase *adbase; {
    register afs_int32 code;

    code = ReplayLog(adbase);
    if (code) return code;
    code = InitializeDB(adbase);
    return code;
}

/* Main interaction loop for the recovery manager
 * The recovery light-weight process only runs when you're the
 * synchronization site.  It performs the following tasks, if and only
 * if the prerequisite tasks have been performed successfully (it
 * keeps track of which ones have been performed in its bit map,
 * urecovery_state).
 *
 * First, it is responsible for probing that all servers are up.  This
 * is the only operation that must be performed even if this is not
 * yet the sync site, since otherwise this site may not notice that
 * enough other machines are running to even elect this guy to be the
 * sync site.
 *
 * After that, the recovery process does nothing until the beacon and
 * voting modules manage to get this site elected sync site.
 *
 * After becoming sync site, recovery first attempts to find the best
 * database available in the network (it must do this in order to
 * ensure finding the latest committed data).  After finding the right
 * database, it must fetch this dbase to the sync site.
 *
 * After fetching the dbase, it relabels it with a new version number,
 * to ensure that everyone recognizes this dbase as the most recent
 * dbase.
 *
 * One the dbase has been relabelled, this machine can start handling
 * requests.  However, the recovery module still has one more task:
 * propagating the dbase out to everyone who is up in the network.
 */
urecovery_Interact() {
    afs_int32 code, tcode;
    struct ubik_server *bestServer;
    struct ubik_server *ts;
    int dbok, doingRPC, now;
    afs_int32 lastProbeTime, lastDBVCheck;
    /* if we're the sync site, the best db version we've found yet */
    static struct ubik_version bestDBVersion;
    struct ubik_version tversion;
    struct timeval tv;
    int length, tlen, offset, file, nbytes;
    struct rx_call *rxcall;
    char tbuffer[256];
    struct ubik_stat ubikstat;
    struct in_addr inAddr;

    /* otherwise, begin interaction */
    urecovery_state = 0;
    lastProbeTime = 0;
    lastDBVCheck = 0;
    while (1) {
	/* Run through this loop every 4 seconds */
	tv.tv_sec = 4;
	tv.tv_usec = 0;
	IOMGR_Select(0, 0, 0, 0, &tv);

	ubik_dprint("recovery running in state %x\n", urecovery_state);

	/* Every 30 seconds, check all the down servers and mark them
	 * as up if they respond. When a server comes up or found to
	 * not be current, then re-find the the best database and 
	 * propogate it.
	 */
	if ( (now = FT_ApproxTime()) > 30 + lastProbeTime) {
	    for (ts=ubik_servers,doingRPC=0; ts; ts=ts->next) {
		if (!ts->up) {
		    doingRPC = 1;
		    code = DoProbe(ts); 
		    if (code == 0) {
		       ts->up = 1;
		       urecovery_state &= ~UBIK_RECFOUNDDB;
		    }
		} else if (!ts->currentDB) {
		    urecovery_state &= ~UBIK_RECFOUNDDB;
		}
	    }
	    if (doingRPC) 
		now = FT_ApproxTime();
	    lastProbeTime = now;
	}

	/* Mark whether we are the sync site */
	if (!ubeacon_AmSyncSite()) {
	    urecovery_state &= ~UBIK_RECSYNCSITE;
	    continue;		/* nothing to do */
	}
	urecovery_state |= UBIK_RECSYNCSITE;
	
	/* If a server has just come up or if we have not found the 
	 * most current database, then go find the most current db.
	 */
	if (!(urecovery_state & UBIK_RECFOUNDDB)) {
	    bestServer = (struct ubik_server *) 0;
	    bestDBVersion.epoch = 0;
	    bestDBVersion.counter = 0;
	    for(ts=ubik_servers; ts; ts=ts->next) {
	        if (!ts->up) continue;  /* don't bother with these guys */
                if (ts->isClone) continue;
		code = DISK_GetVersion(ts->disk_rxcid, &ts->version);
		if (code == 0) {
		    /* perhaps this is the best version */
		    if (vcmp(ts->version, bestDBVersion) > 0) {
			/* new best version */
			bestDBVersion = ts->version;
			bestServer = ts;
		    }
		}
	    }
	    /* take into consideration our version. Remember if we,
	     * the sync site, have the best version. Also note that
	     * we may need to send the best version out.
	     */
	    if (vcmp(ubik_dbase->version, bestDBVersion) >= 0) {
		bestDBVersion = ubik_dbase->version;
		bestServer = (struct ubik_server *) 0;
	       urecovery_state |= UBIK_RECHAVEDB;
	    } else {
	       /* Clear the flag only when we know we have to retrieve
		* the db. Because urecovery_AllBetter() looks at it.
		*/
	       urecovery_state &= ~UBIK_RECHAVEDB;
	    }
	    lastDBVCheck = FT_ApproxTime();
	    urecovery_state |=  UBIK_RECFOUNDDB;
	    urecovery_state &= ~UBIK_RECSENTDB;
	}
	if (!(urecovery_state &	UBIK_RECFOUNDDB)) continue; /* not ready */

	/* If we, the sync site, do not have the best db version, then
	 * go and get it from the server that does.
	 */
	if ((urecovery_state & UBIK_RECHAVEDB) || !bestServer) {
	   urecovery_state |= UBIK_RECHAVEDB;
	} else {
	   /* we don't have the best version; we should fetch it. */
	   ObtainWriteLock(&ubik_dbase->versionLock);
	   urecovery_AbortAll(ubik_dbase);

	   /* Rx code to do the Bulk fetch */
	   file = 0;
	   offset = 0;
	   rxcall = rx_NewCall(bestServer->disk_rxcid);

	   ubik_print("Ubik: Synchronize database with server %s\n", afs_inet_ntoa(bestServer->addr[0]));

	   code = StartDISK_GetFile(rxcall, file);
	   if (code) { 
	      ubik_dprint("StartDiskGetFile failed=%d\n", code); 
	      goto FetchEndCall;
	   }
	   nbytes = rx_Read(rxcall, &length, sizeof(afs_int32));
	   length = ntohl(length);
	   if (nbytes != sizeof(afs_int32)) { 
	      ubik_dprint("Rx-read length error=%d\n", code=BULK_ERROR); 
	      code = EIO;
	      goto FetchEndCall;
	   }

	   /* Truncate the file firest */
	   code = (*ubik_dbase->truncate)(ubik_dbase, file, 0);
	   if (code) {
	      ubik_dprint("truncate io error=%d\n", code); 
	      goto FetchEndCall;
	   }

	   /* give invalid label during file transit */
	   tversion.epoch = 0;
	   tversion.counter = 0;
	   code = (*ubik_dbase->setlabel)(ubik_dbase, file, &tversion);
	   if (code) {
	      ubik_dprint("setlabel io error=%d\n", code); 
	      goto FetchEndCall;
	   }

	   while (length > 0)	{
	      tlen = (length > sizeof(tbuffer) ? sizeof(tbuffer) : length);
	      nbytes = rx_Read(rxcall, tbuffer, tlen);
	      if (nbytes != tlen) { 
		 ubik_dprint("Rx-read bulk error=%d\n", code=BULK_ERROR); 
		 code = EIO;
		 goto FetchEndCall;
	      }
	      nbytes = (*ubik_dbase->write)(ubik_dbase, file, tbuffer, offset, tlen);
	      if (nbytes != tlen) {
		 code = UIOERROR;
		 goto FetchEndCall;
	      }
	      offset += tlen;
	      length -= tlen;
	   }
	   code = EndDISK_GetFile(rxcall, &tversion);
FetchEndCall:
	   tcode = rx_EndCall(rxcall, code);
	   if (!code) code = tcode;
	   if (!code) {
	      /* we got a new file, set up its header */
	      urecovery_state |= UBIK_RECHAVEDB;
	      bcopy(&tversion, &ubik_dbase->version, sizeof(struct ubik_version));
	      (*ubik_dbase->sync)(ubik_dbase, 0);	/* get data out first */
	      /* after data is good, sync disk with correct label */
	      code = (*ubik_dbase->setlabel)(ubik_dbase, 0, &ubik_dbase->version);
	   }
	   if (code) {
	      ubik_dbase->version.epoch = 0;
	      ubik_dbase->version.counter = 0;
	      ubik_print("Ubik: Synchronize database failed (error = %d)\n", code);
	   } else {
	      ubik_print("Ubik: Synchronize database completed\n");
	   }
	   udisk_Invalidate(ubik_dbase, 0);	/* data has changed */
	   LWP_NoYieldSignal(&ubik_dbase->version);
	   ReleaseWriteLock(&ubik_dbase->versionLock);
	}
	if (!(urecovery_state &	UBIK_RECHAVEDB)) continue; /* not ready */
	
	/* If the database was newly initialized, then when we establish quorum, write
	 * a new label. This allows urecovery_AllBetter() to allow access for reads.
	 * Setting it to 2 also allows another site to come along with a newer
	 * database and overwrite this one.
	 */
	if (ubik_dbase->version.epoch == 1) {
	   ObtainWriteLock(&ubik_dbase->versionLock);
	   urecovery_AbortAll(ubik_dbase);
	   ubik_epochTime = 2;
	   ubik_dbase->version.epoch   = ubik_epochTime;
	   ubik_dbase->version.counter = 1;
	   code = (*ubik_dbase->setlabel) (ubik_dbase, 0, &ubik_dbase->version);
	   udisk_Invalidate(ubik_dbase, 0);           /* data may have changed */
	   LWP_NoYieldSignal(&ubik_dbase->version);
	   ReleaseWriteLock(&ubik_dbase->versionLock);
	}

	/* Check the other sites and send the database to them if they
	 * do not have the current db.
	 */
	if (!(urecovery_state & UBIK_RECSENTDB)) {
	    /* now propagate out new version to everyone else */
	    dbok = 1;	    /* start off assuming they all worked */

	    ObtainWriteLock(&ubik_dbase->versionLock);
	    /*
	     * Check if a write transaction is in progress. We can't send the
	     * db when a write is in progress here because the db would be
	     * obsolete as soon as it goes there. Also, ops after the begin
	     * trans would reach the recepient and wouldn't find a transaction
	     * pending there.  Frankly, I don't think it's possible to get past
	     * the write-lock above if there is a write transaction in progress,
	     * but then, it won't hurt to check, will it?
	     */
	    if (ubik_dbase->flags & DBWRITING) {
	      struct timeval tv;
	      int safety = 0;
	      tv.tv_sec =  0;
	      tv.tv_usec = 50000;
	      while ((ubik_dbase->flags & DBWRITING) && (safety < 500)) {
		ReleaseWriteLock(&ubik_dbase->versionLock);	
		/* sleep for a little while */
		IOMGR_Select(0, 0, 0, 0, &tv);
		tv.tv_usec += 10000; safety++;
		ObtainWriteLock(&ubik_dbase->versionLock);		     
	      }
	    }

	    for(ts=ubik_servers; ts; ts=ts->next) {
                inAddr.s_addr = ts->addr[0];
		if (!ts->up) {
                    ubik_dprint("recovery cannot send version to %s\n",
	                                afs_inet_ntoa(inAddr.s_addr));
		    dbok = 0;
		    continue;
		}
                ubik_dprint("recovery sending version to %s\n",
                            afs_inet_ntoa(inAddr.s_addr));
		if (vcmp(ts->version, ubik_dbase->version) != 0) {
                    ubik_dprint("recovery stating local database\n");

		    /* Rx code to do the Bulk Store */
		    code = (*ubik_dbase->stat)(ubik_dbase, 0, &ubikstat);
		    if (!code) {
			length = ubikstat.size;
			file = offset = 0;
			rxcall = rx_NewCall(ts->disk_rxcid);
			code = StartDISK_SendFile(rxcall, file, length, &ubik_dbase->version);
			if (code) { 
			    ubik_dprint("StartDiskSendFile failed=%d\n", code); 
			    goto StoreEndCall;
			}
			while (length > 0)	{
			    tlen = (length > sizeof(tbuffer) ? sizeof(tbuffer) : length);
			    nbytes = (*ubik_dbase->read)(ubik_dbase, file, tbuffer, offset, tlen);
			    if (nbytes != tlen) {
				ubik_dprint("Local disk read error=%d\n", code=UIOERROR);
				goto StoreEndCall;
			    }
			    nbytes = rx_Write(rxcall, tbuffer, tlen);
			    if (nbytes != tlen) { 
				ubik_dprint("Rx-write bulk error=%d\n", code=BULK_ERROR); 
				goto StoreEndCall;
			    }
			    offset += tlen;
			    length -= tlen;
			}
			code = EndDISK_SendFile(rxcall);
StoreEndCall:
			code = rx_EndCall(rxcall, code);
		    }
		    if (code == 0) {
			/* we set a new file, process its header */
			ts->version = ubik_dbase->version;
			ts->currentDB = 1;
		    }
		    else dbok = 0;
		}
		else {
		    /* mark file up to date */
		    ts->currentDB = 1;
		}
	    }
	    ReleaseWriteLock(&ubik_dbase->versionLock);
	    if (dbok) urecovery_state |= UBIK_RECSENTDB;
	}
    }
}

/*
** send a Probe to all the network address of this server 
** Return 0  if success, else return 1
*/
DoProbe(server)
struct ubik_server *server;
{
    struct rx_connection *conns[UBIK_MAX_INTERFACE_ADDR];
    struct rx_connection *connSuccess = 0;
    int 		i, j;
    afs_uint32		addr;
    char		buffer[32]; 
    extern afs_int32	ubikSecIndex;
    extern struct rx_securityClass	*ubikSecClass;

    for (i=0; (addr=server->addr[i]) && (i<UBIK_MAX_INTERFACE_ADDR);i++)
    {
	conns[i] = rx_NewConnection(addr, ubik_callPortal, DISK_SERVICE_ID, 
					ubikSecClass, ubikSecIndex);

		/* user requirement to use only the primary interface */
	if ( ubikPrimaryAddrOnly )
	{
	    i = 1;
	    break;
	}
    }
    assert(i);	/* at least one interface address for this server */

    multi_Rx(conns,i)
    {
	multi_DISK_Probe();
	if ( !multi_error )                    /* first success */
	{
	    addr = server->addr[multi_i];     /* successful interface addr */

	    if ( server->disk_rxcid)	      /* destroy existing conn */
		rx_DestroyConnection(server->disk_rxcid); 
	    if ( server->vote_rxcid)
		rx_DestroyConnection(server->vote_rxcid);

		                              /* make new connections */
	    server->disk_rxcid = conns[multi_i];
	    server->vote_rxcid = rx_NewConnection(addr, ubik_callPortal,
		VOTE_SERVICE_ID, ubikSecClass, ubikSecIndex);/* for vote reqs*/

	    connSuccess        = conns[multi_i];
	    strcpy(buffer, (char*)afs_inet_ntoa(server->addr[0]));
	    ubik_print("ubik:server %s is back up: will be contacted through %s\n",
			buffer, afs_inet_ntoa(addr));

	    multi_Abort;
	}
    } multi_End_Ignore;	

    /* Destroy all connections except the one on which we succeeded */
    for ( j=0; j < i; j++)
	if ( conns[j] != connSuccess )
	    rx_DestroyConnection(conns[j] );

    if (!connSuccess)
	ubik_dprint("ubik:server %s still down\n",afs_inet_ntoa(server->addr[0]));

    if ( connSuccess ) return 0;    /* success */
	else return 1;              /* failure */
}
