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[openafs.git] / src / ubik / beacon.c

/*
 * 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 <sys/time.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h>
#endif
#include <errno.h>
#include <lock.h>
#include <rx/xdr.h>
#include <rx/rx.h>
#include <rx/rx_multi.h>
#ifndef AFS_NT40_ENV
#include <afs/afsutil.h>
#include <afs/netutils.h>
#endif

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

/* statics used to determine if we're the sync site */
static afs_int32 syncSiteUntil = 0;         /* valid only if amSyncSite */
int ubik_amSyncSite = 0;            /* flag telling if I'm sync site */
static nServers;                    /* total number of servers */
static char amIMagic=0;             /* is this host the magic host */
extern struct rx_securityClass *rxnull_NewClientSecurityObject();
int (*ubik_CRXSecurityProc)();
char *ubik_CRXSecurityRock;
afs_int32 ubikSecIndex;
struct rx_securityClass     *ubikSecClass;


/* Module responsible for both deciding if we're currently the sync site,
 * and keeping collecting votes so as to stay sync site.
 *
 * The basic module contacts all of the servers it can, trying to get them to vote
 * for this server for sync site.  The vote request message (called a beacon message)
 * also specifies until which time this site claims to be the sync site, if at all, thus enabling
 * receiving sites to know how long the sync site guarantee is made for.
 *
 * Each  of these beacon messages is thus both a declaration of how long this site will
 * remain sync site, and an attempt to extend that time by collecting votes for a later
 * sync site extension.
 *
 * The voting module is responsible for choosing a reasonable time until which it promises
 * not to vote for someone else.  This parameter (BIG seconds) is not actually passed in
 * the interface (perhaps it should be?) but is instead a compile time constant that both
 * sides know about.
 
 * The beacon and vote modules work intimately together; the vote module decides how long
 * it should promise the beacon module its vote, and the beacon module takes all of these
 * votes and decides for how long it is the synchronization site.
 */

/* procedure called from debug rpc call to get this module's state for debugging */
ubeacon_Debug(aparm)
register struct ubik_debug *aparm; {
    /* fill in beacon's state fields in the ubik_debug structure */
    aparm->syncSiteUntil = syncSiteUntil;
    aparm->nServers = nServers;
}

/* procedure that determines whether this site has enough current votes to remain sync site.
 *  called from higher-level modules (everything but the vote module).
 *
 * If we're the sync site, check that our guarantees, obtained by the ubeacon_Interact
 * light-weight process, haven't expired.  We're sync site as long as a majority of the
 * servers in existence have promised us unexpired guarantees.  The variable ubik_syncSiteUntil
 * contains the time at which the latest of the majority of the sync site guarantees expires
 * (if the variable ubik_amSyncSite is true)
 * This module also calls up to the recovery module if it thinks that the recovery module
 * may have to pick up a new database (which offucr sif we lose the sync site votes).
 */
ubeacon_AmSyncSite() {
    register afs_int32 now;
    register afs_int32 rcode;
    
    /* special case for fast startup */
    if (nServers == 1) {
        return 1;       /* one guy is always the sync site */
    }

    if (ubik_amSyncSite == 0) rcode = 0;  /* if I don't think I'm the sync site, say so */
    else {
        now = FT_ApproxTime();
        if (syncSiteUntil <= now) {         /* if my votes have expired, say so */
            if (ubik_amSyncSite) ubik_dprint("Ubik: I am no longer the sync site\n");
            ubik_amSyncSite = 0;
            rcode = 0;
        }
        else {
            rcode = 1;              /* otherwise still have the required votes */
        }
    }
    if (rcode == 0) urecovery_ResetState(); /* force recovery to re-execute */
    ubik_dprint("beacon: amSyncSite is %d\n", rcode);
    return rcode;
}

/* setup server list; called with two parms, first is my address, second is list of other servers
 * called only at initialization to set up the list of servers to contact for votes.  Just creates
 * the server structure.  Note that there are two connections in every server structure, one for
 * vote calls (which must always go through quickly) and one for database operations, which
 * are subject to waiting for locks.  If we used only one, the votes would sometimes get
 * held up behind database operations, and the sync site guarantees would timeout
 * even though the host would be up for communication.
 *
 * The "magic" host is the one with the lowest internet address.  It is
 * magic because its vote counts epsilon more than the others.  This acts
 * as a tie-breaker when we have an even number of hosts in the system.
 * For example, if the "magic" host is up in a 2 site system, then it
 * is sync site.  Without the magic host hack, if anyone crashed in a 2
 * site system, we'd be out of business.
 */
ubeacon_InitServerList(ame, aservers)
    afs_int32 ame;
    register afs_int32 aservers[]; {
    register struct ubik_server *ts;
    register afs_int32 servAddr;
    register afs_int32 i, code;
    afs_int32 magicHost;
    struct ubik_server *magicServer;

    /* verify that the addresses passed in are correct */
    if ( code = verifyInterfaceAddress(&ame, aservers ))
        return code;

    /* get the security index to use, if we can */
    if (ubik_CRXSecurityProc) {
        i = (*ubik_CRXSecurityProc)(ubik_CRXSecurityRock, &ubikSecClass, &ubikSecIndex);
    }
    else i = 1;
    if (i) {
        /* don't have sec module yet */
        ubikSecIndex = 0;
        ubikSecClass = rxnull_NewClientSecurityObject();
    }
    i = 0;
    magicHost = ntohl(ame);     /* do comparisons in host order */
    magicServer = (struct ubik_server *) 0;
    while (servAddr = *aservers++) {
        if (i >= MAXSERVERS) return UNHOSTS;        /* too many hosts */
        ts = (struct ubik_server *) malloc(sizeof(struct ubik_server));
        bzero(ts, sizeof(struct ubik_server));
        ts->next = ubik_servers;
        ubik_servers = ts;
        ts->addr[0] = servAddr; /* primary address in  net byte order */
        ts->vote_rxcid = rx_NewConnection(servAddr, ubik_callPortal, VOTE_SERVICE_ID, ubikSecClass, ubikSecIndex);      /* for vote reqs */
        ts->disk_rxcid = rx_NewConnection(servAddr, ubik_callPortal, DISK_SERVICE_ID, ubikSecClass, ubikSecIndex);      /* for disk reqs */
        ts->up = 1;
        if (ntohl((afs_uint32) servAddr) < (afs_uint32) magicHost) {
            magicHost = ntohl(servAddr);
            magicServer = ts;
        }
        i++;
    }
    if (magicServer) magicServer->magic = 1;    /* remember for when counting votes */
    else amIMagic = 1;
    nServers = i+1;     /* count this server as well as the remotes */
    ubik_quorum = (nServers>>1)+1;      /* compute the majority figure */
                                        /* send addrs to all other servers */
    code = updateUbikNetworkAddress(ubik_host);
    if ( code )
        return code;            

/* Shoud we set some defaults for RX??
    r_retryInterval = 2;        
    r_nRetries = (RPCTIMEOUT/r_retryInterval);
*/
    if (nServers == 1) {    /* special case 1 server */
        if (!ubik_amSyncSite) ubik_dprint("Ubik: I am the sync site - 1 server\n");
        ubik_amSyncSite = 1;
        syncSiteUntil = 0x7fffffff; /* quite a while */
    }
    return 0;
}

/* main lwp loop for code that sends out beacons.  This code only runs while
 * we're sync site or we want to be the sync site.  It runs in its very own light-weight
 * process.
 */
ubeacon_Interact() { 
    register afs_int32 code;
    struct timeval tt;
    struct rx_connection *connections[MAXSERVERS];
    struct ubik_server *servers[MAXSERVERS];
    register afs_int32 i;
    register struct ubik_server *ts;
    afs_int32 temp, yesVotes, lastWakeupTime, oldestYesVote, syncsite;
    struct ubik_tid ttid;
    afs_int32 startTime;

    /* loop forever getting votes */
    lastWakeupTime = 0;     /* keep track of time we last started a vote collection */
    while (1) {

        /* don't wakeup more than every POLLTIME seconds */
        temp = (lastWakeupTime + POLLTIME) - FT_ApproxTime();
        /* don't sleep if last collection phase took too long (probably timed someone out ) */
        if (temp > 0) {
            if (temp > POLLTIME) temp = POLLTIME;
            tt.tv_sec = temp;
            tt.tv_usec = 0;
            code = IOMGR_Select(0, 0, 0, 0, &tt);
        }
        else code = 0;

        lastWakeupTime = FT_ApproxTime();   /* started a new collection phase */

        if (nServers == 1) continue;    /* special-case 1 server for speedy startup */

        if (!uvote_ShouldIRun()) continue;  /* if voter has heard from a better candidate than us, don't bother running */

        /* otherwise we should run for election, or we're the sync site (and have already won);
            send out the beacon packets */
        /* build list of all up hosts (noticing dead hosts are running again
            is a task for the recovery module, not the beacon module), and
            prepare to send them an r multi-call containing the beacon message */
        i = 0;      /* collect connections */
        for(ts = ubik_servers; ts; ts=ts->next) {
            if (ts->up && ts->addr[0] != ubik_host[0]) {
                servers[i] = ts;
                connections[i++] = ts->vote_rxcid;
            }
        }
        servers[i] = (struct ubik_server *) 0;  /* end of list */
        /* note that we assume in the vote module that we'll always get at least BIGTIME 
            seconds of vote from anyone who votes for us, which means we can conservatively
            assume we'll be fine until SMALLTIME seconds after we start collecting votes */
        /* this next is essentially an expansion of rgen's ServBeacon routine */

        ttid.epoch = ubik_epochTime;
        if (ubik_dbase->flags & DBWRITING) {
            /*
             * if a write is in progress, we have to send the writeTidCounter
             * which holds the tid counter of the write transaction , and not
             * send the tidCounter value which holds the tid counter of the
             * last transaction.
             */
            ttid.counter = ubik_dbase->writeTidCounter;
          }
        else
            ttid.counter = ubik_dbase->tidCounter+1;

        /* now analyze return codes, counting up our votes */
        yesVotes = 0;               /* count how many to ensure we have quorum */
        oldestYesVote = 0x3fffffff; /* time quorum expires */
        syncsite= ubeacon_AmSyncSite();
        startTime = FT_ApproxTime();
        /*
         * Don't waste time using mult Rx calls if there are no connections out there
         */
        if (i > 0) {
            multi_Rx(connections, i) {
                multi_VOTE_Beacon(syncsite, startTime, &ubik_dbase->version, &ttid);
                temp = FT_ApproxTime();     /* now, more or less */
                ts = servers[multi_i];
                ts->lastBeaconSent = temp;
                code = multi_error;
                /* note that the vote time (the return code) represents the time
                   the vote was computed, *not* the time the vote expires.  We compute
                   the latter down below if we got enough votes to go with */
                if (code > 0) {
                    ts->lastVoteTime = code;
                    if (code < oldestYesVote) oldestYesVote = code;
                    ts->lastVote = 1;
                    yesVotes += 2;
                    if (ts->magic) yesVotes++;  /* the extra epsilon */
                    ts->up = 1; /* server is up (not really necessary: recovery does this for real) */
                    ts->beaconSinceDown = 1;
                    ubik_dprint("yes vote from host %s\n",afs_inet_ntoa(ts->addr[0]));
                }
                else if (code == 0) {
                    ts->lastVoteTime = temp;
                    ts->lastVote = 0;
                    ts->beaconSinceDown = 1;
                    ubik_dprint("no vote from %s\n", afs_inet_ntoa(ts->addr[0]));
                }
                else if (code < 0) {
                    ts->up = 0;
                    ts->beaconSinceDown = 0;
                    urecovery_LostServer();
                    ubik_dprint("time out from %s\n", afs_inet_ntoa(ts->addr[0]));
                }
            } multi_End;
        }
        /* now call our own voter module to see if we'll vote for ourself.  Note that
            the same restrictions apply for our voting for ourself as for our voting
            for anyone else. */
        i = SVOTE_Beacon((struct rx_connection *) 0, ubeacon_AmSyncSite(), startTime, &ubik_dbase->version, &ttid);
        if (i) {
            yesVotes += 2;
            if (amIMagic) yesVotes++;   /* extra epsilon */
            if (i < oldestYesVote) oldestYesVote = i;
        }

        /* now decide if we have enough votes to become sync site.
            Note that we can still get enough votes even if we didn't for ourself. */
        if (yesVotes > nServers) {  /* yesVotes is bumped by 2 or 3 for each site */
            if (!ubik_amSyncSite) ubik_dprint("Ubik: I am the sync site\n");
            ubik_amSyncSite = 1;
            syncSiteUntil = oldestYesVote + SMALLTIME;
            LWP_NoYieldSignal(&ubik_amSyncSite);
        }
        else {
            if (ubik_amSyncSite) ubik_dprint("Ubik: I am no longer the sync site\n");
            ubik_amSyncSite = 0;
            urecovery_ResetState(); /* tell recovery we're no longer the sync site */
        }

    }   /* while loop */
}

/* 
* Input Param   : ame is the pointer to my IP address specified in the
*                 CellServDB file. aservers is an array containing IP 
*                 addresses of remote ubik servers. The array is 
*                 terminated by a zero address.
*
* Algorithm     : Verify that my IP addresses 'ame' does actually exist
*                 on this machine.  If any of my IP addresses are there 
*                 in the remote server list 'aserver', remove them from 
*                 this list.  Update global variable ubik_host[] with 
*                 my IP addresses.
*
* Return Values : 0 on success, non-zero on failure
*/
verifyInterfaceAddress(ame, aservers)
afs_uint32 *ame;                /* one of my interface addr in net byte order */
afs_uint32 aservers[];  /* list of all possible server addresses */
{
    afs_uint32  myAddr[UBIK_MAX_INTERFACE_ADDR], *servList;
    int         count, index, found, i, j, totalServers, start, end;

    /* count the number of servers */
    for ( totalServers=0, servList = aservers; *servList; servList++)
        totalServers++;

#ifdef AFS_NT40_ENV 
    /* for now use getaddr(). use getAllAddr when implemented */
    myAddr[0] =  rxi_getaddr();
    count = (myAddr[0] != 0);
#else
    if(AFSDIR_SERVER_NETRESTRICT_FILEPATH || AFSDIR_SERVER_NETINFO_FILEPATH) {
      /*
       * Find addresses we are supposed to register as per the netrestrict file
       * if it exists, else just register all the addresses we find on this 
       * host as returned by rx_getAllAddr (in NBO)
       */
      char reason[1024];
      count=parseNetFiles(myAddr,NULL,NULL,UBIK_MAX_INTERFACE_ADDR,
                          reason,AFSDIR_SERVER_NETINFO_FILEPATH,
                          AFSDIR_SERVER_NETRESTRICT_FILEPATH);
      if(count<0) {
        ubik_print("ubik: Can't register any valid addresses:%s\n",reason);
        ubik_print("Aborting..\n");
        return UBADHOST;
      }
    }
    else {
      /* get all my interface addresses in net byte order */
      count = rx_getAllAddr(myAddr, UBIK_MAX_INTERFACE_ADDR); 
    }
#endif

    if ( count <= 0 )           /* no address found */
    {
        ubik_print("ubik: No network addresses found, aborting..");
        return UBADHOST;
    }

    /* verify that the My-address passed in by ubik is correct */
    for ( j=0, found = 0; j < count; j++)
    {
        if ( *ame == myAddr[j] ) /* both in net byte order */
        {
            found = 1;
            break;
        }
    }
         
    if ( !found )
    {
        ubik_print("ubik: primary address %s does not exist\n",
                        afs_inet_ntoa(*ame));
        return UBADHOST;
    }

    /* if any of my addresses are there in serverList, then
    ** use that as my primary addresses : the higher level 
    ** application screwed up in dealing with multihomed concepts
    */
    for ( j=0, found = 0; j < count; j++)
    {
        for ( i=0; i < totalServers; i++)
            if ( myAddr[j] == aservers[i] )     
            {
                *ame = aservers[i];
                aservers[i]  = 0 ; 
                found = 1;
            }
    }
    if ( found )
        ubik_print("Using %s as my primary address\n", afs_inet_ntoa(*ame) );

    /* get rid of servers which were purged because all 
    ** those interface addresses are myself 
    */
    for ( start=0, end=totalServers-1; (start<end) ; start++, end--)
    {
        /* find the first zero entry from the beginning */
        for ( ; (start < end) && ( aservers[start] ); start++);

        /* find the last non-zero entry from the end */
        for ( ; (end >= 0) && ( !aservers[end] ); end-- );

        /* if there is nothing more to purge, exit from loop */
        if ( start >= end ) break;

        /* move the entry */
        aservers[start] = aservers[end];
        aservers[end]   = 0;            /* this entry was moved */
    }
        
    /* update all my addresses in ubik_host in such a way 
    ** that ubik_host[0] has the primary address 
    */
    ubik_host[0] = *ame;        
    for ( j=0, i=1; j < count; j++)
        if ( *ame != myAddr[j] )
            ubik_host[i++] =  myAddr[j];

    return 0;   /* return success */
}       


/* 
* Input Param   : ubik_host is an array containing all my IP addresses.
*
* Algorithm     : Do an RPC to all remote ubik servers infroming them 
*                 about my IP addresses. Get their IP addresses and
*                 update my linked list of ubik servers 'ubik_servers'
*
* Return Values : 0 on success, non-zero on failure
*/
int
updateUbikNetworkAddress(ubik_host)
afs_uint32 ubik_host[UBIK_MAX_INTERFACE_ADDR];
{
    int                 j, count, found, index, code = 0;
    UbikInterfaceAddr   inAddr, outAddr;
    struct rx_connection *conns[MAXSERVERS];
    struct ubik_server  *ts, *server[MAXSERVERS];
    char                buffer[32];

    for ( count = 0, ts=ubik_servers; ts; count++, ts = ts->next )
    {
        conns[count]  = ts->disk_rxcid;
        server[count] = ts;
    }


    /* inform all other servers only if there are more than one
       database servers in the cell */

    if ( count > 0) {
        
        for ( j=0; j < UBIK_MAX_INTERFACE_ADDR; j++)
            inAddr.hostAddr[j] = ntohl(ubik_host[j]);

    
        /* do the multi-RX RPC to all other servers */
        multi_Rx(conns, count) {
            multi_DISK_UpdateInterfaceAddr(&inAddr, &outAddr);
            ts = server[multi_i]; /* reply received from this server */
            if ( !multi_error ) {
                if ( ts->addr[0] != htonl(outAddr.hostAddr[0]) ) {
                    code = UBADHOST;
                    strcpy(buffer, (char*)afs_inet_ntoa(ts->addr[0]));
                    ubik_print("ubik:Two primary addresses for same server \
                    %s %s\n", buffer, afs_inet_ntoa(htonl(outAddr.hostAddr[0])));
                }
                else {
                    for ( j=1; j < UBIK_MAX_INTERFACE_ADDR; j++)
                        ts->addr[j] = htonl(outAddr.hostAddr[j]);
                }
            }
            else if ( multi_error == RXGEN_OPCODE ) {/* pre 3.5 remote server */
                ubik_print("ubik server %s does not support UpdateInterfaceAddr RPC\n", afs_inet_ntoa(ts->addr[0]));
            }
            else if ( multi_error == UBADHOST ) {
                code = UBADHOST; /* remote CellServDB inconsistency */
                ubik_print("Inconsistent Cell Info on server: ");
                for ( j=0; j < UBIK_MAX_INTERFACE_ADDR && ts->addr[j]; j++)
                    printf("%s ", afs_inet_ntoa(ts->addr[j]));
                printf("\n");
                fflush(stdout); fflush(stderr);     
            }
            else {
                ts->up= 0;      /* mark the remote server as down */
            }
        } multi_End;
    }
    return code;
}