diff options
Diffstat (limited to 'source3/lib/wins_srv.c')
| -rw-r--r-- | source3/lib/wins_srv.c | 393 |
1 files changed, 90 insertions, 303 deletions
diff --git a/source3/lib/wins_srv.c b/source3/lib/wins_srv.c index 0181ee0956..cad0d06e49 100644 --- a/source3/lib/wins_srv.c +++ b/source3/lib/wins_srv.c @@ -1,7 +1,7 @@ /* Unix SMB/CIFS implementation. Samba utility functions - Copyright (C) Andrew Tridgell 1992-1998 + Copyright (C) Andrew Tridgell 1992-2002 Copyright (C) Christopher R. Hertel 2000 This program is free software; you can redistribute it and/or modify @@ -21,319 +21,106 @@ #include "includes.h" -/* -------------------------------------------------------------------------- ** - * Discussion... - * - * This module implements WINS failover. - * - * Microsoft's WINS servers provide a feature called WINS replication, - * which synchronises the WINS name databases between two or more servers. - * This means that the two servers can be used interchangably (more or - * less). WINS replication is particularly useful if you are trying to - * synchronise the WINS namespace between servers in remote locations, or - * if your WINS servers tend to crash a lot. - * - * WINS failover allows the client to 'switch' to a different WINS server - * if the current WINS server mysteriously disappears. On Windows - * systems, this is typically represented as 'primary' and 'secondary' - * WINS servers. - * - * Failover only works if the WINS servers are synced. If they are not, - * then - * a) if the primary WINS server never fails the client will never 'see' - * the secondary (or tertiary or...) WINS server name space. - * b) if the primary *does* fail, the client will be entering an - * unfamiliar namespace. The client itself will not be registered in - * that namespace and any names which match names in the previous - * space will likely resolve to different host IP addresses. - * - * One key thing to remember regarding WINS failover is that Samba does - * not (yet) implement WINS replication. For those interested, sniff port - * 42 (TCP? UDP? ...dunno off hand) and see what two MS WINS servers do. - * - * At this stage, only failover is implemented. The next thing is to add - * support for multi-WINS server registration and query (multi-membership). - * - * Multi-membership is a little wierd. The idea is that the client can - * register itself with multiple non-replicated WINS servers, and query - * all of those servers (in a prescribed sequence) to resolve a name. - * - * The implications of multi-membership are not quite clear. Worth - * trying, I suppose. Changes will be needed in the name query and - * registration code to accomodate this feature. Also, there will need to - * be some sort of syntax extension for the 'wins server' parameter in - * smb.conf. I'm thinking that a colon could be used as a separator. - * - * Of course, for each WINS namespace there might be multiple, synced WINS - * servers. The change to this module would likely be the addition of a - * linked list of linked lists. - * - * crh@samba.org - */ -/* -------------------------------------------------------------------------- ** - * Defines... - * - * NECROMANCYCLE - The dead server retry period, in seconds. When a WINS - * server is declared dead, wait this many seconds before - * attempting to communicate with it. - */ +/* how long a server is marked dead for */ +#define DEATH_TIME 600 -#define NECROMANCYCLE 600 /* 600 seconds == 10 minutes. */ +/* a list of wins server that are marked dead. */ +static struct wins_dead { + struct in_addr ip; + time_t revival; /* when it will be revived */ + struct wins_dead *next, *prev; +} *dead_servers; -/* -------------------------------------------------------------------------- ** - * Typedefs... - */ -typedef struct - { - ubi_slNode node; /* Linked list node structure. */ - time_t mourning; /* If > current time then server is dead, Jim. */ - char *server; /* DNS name or IP of NBNS server to query. */ - struct in_addr ip_addr; /* Cache translated IP. */ - } list_entry; - -/* -------------------------------------------------------------------------- ** - * Private, static variables. - */ - -static ubi_slNewList( wins_srv_list ); - -/* -------------------------------------------------------------------------- ** - * Functions... - */ - - -BOOL wins_srv_load_list( char *src ) - /* ------------------------------------------------------------------------ ** - * Create or recreate the linked list of failover WINS servers. - * - * Input: src - String of DNS names and/or IP addresses delimited by the - * characters listed in LIST_SEP (see include/local.h). - * - * Output: True if at least one name or IP could be parsed out of the - * list, else False. - * - * Notes: There is no syntax checking done on the names or IPs. We do - * check to see if the field is an IP, in which case we copy it - * to the ip_addr field of the entry. Don't bother to to a host - * name lookup on all names now. They're done as needed in - * wins_srv_ip(). - * ------------------------------------------------------------------------ ** - */ - { - list_entry *entry; - char *p = src; - pstring wins_id_bufr; - unsigned long count; - - /* Empty the list. */ - while( NULL != (entry =(list_entry *)ubi_slRemHead( wins_srv_list )) ) - { - SAFE_FREE( entry->server ); - SAFE_FREE( entry ); - } - (void)ubi_slInitList( wins_srv_list ); /* shouldn't be needed */ - - /* Parse out the DNS names or IP addresses of the WINS servers. */ - DEBUG( 4, ("wins_srv_load_list(): Building WINS server list:\n") ); - while( next_token( &p, wins_id_bufr, LIST_SEP, sizeof( wins_id_bufr ) ) ) - { - entry = (list_entry *)malloc( sizeof( list_entry ) ); - if( NULL == entry ) - { - DEBUG( 0, ("wins_srv_load_list(): malloc(list_entry) failed.\n") ); - } - else - { - entry->mourning = 0; - /* Create a copy of the server name and store it in the list. */ - if( NULL == (entry->server = strdup( wins_id_bufr )) ) - { - SAFE_FREE( entry ); - DEBUG( 0, - ("wins_srv_load_list(): strdup(\"%s\") failed.\n", wins_id_bufr) ); - } - else - { - /* Add server to list. - * If the server name was actually an IP address we will store that - * too. It it was a DNS name, we will wait until we need to use - * the WINS server before doing the DNS lookup. Since this may be - * a list, and since we will reload the list whenever smb.conf is - * reloaded, there's no point in trying to look up names until we - * need them. ...of course, once we do the lookup we will cache - * the result. See wins_srv_ip(). - */ - if( is_ipaddress( wins_id_bufr ) ) - entry->ip_addr = *interpret_addr2( wins_id_bufr ); - else - entry->ip_addr = *interpret_addr2( "0.0.0.0" ); - (void)ubi_slAddTail( wins_srv_list, entry ); - DEBUGADD( 4, ("%s,\n", wins_id_bufr) ); - } - } - } - - count = ubi_slCount( wins_srv_list ); - DEBUGADD( 4, - ( "%d WINS server%s listed.\n", (int)count, (1==count)?"":"s" ) ); - - return( (count > 0) ? True : False ); - } /* wins_srv_load_list */ - - -struct in_addr wins_srv_ip( void ) - /* ------------------------------------------------------------------------ ** - * Return the IP address of an NBNS (WINS) server thought to be active. - * - * Input: none. - * - * Output: An IP address in struct in_addr form. - * - * Notes: This function will return the IP address of the first available - * NBNS (WINS) server. The order of the list is determined in - * smb.conf. If all of the WINS servers have been marked 'dead' - * then the zero IP (0.0.0.0) is returned. The zero IP is not a - * valid Unicast address on any system. - * - * ------------------------------------------------------------------------ ** - */ - { - time_t now = time(NULL); - list_entry *entry = (list_entry *)ubi_slFirst( wins_srv_list ); - - while( NULL != entry ) - { - if( now >= entry->mourning ) /* Found a live one. */ - { - /* If we don't have the IP, look it up. */ - if( is_zero_ip( entry->ip_addr ) ) - entry->ip_addr = *interpret_addr2( entry->server ); - - /* If we still don't have the IP then kill it, else return it. */ - if( is_zero_ip( entry->ip_addr ) ) - entry->mourning = now + NECROMANCYCLE; - else - return( entry->ip_addr ); - } - entry = (list_entry *)ubi_slNext( entry ); - } - - /* If there are no live entries, return the zero IP. */ - return( *interpret_addr2( "0.0.0.0" ) ); - } /* wins_srv_ip */ - - -char *wins_srv_name( void ) - /* ------------------------------------------------------------------------ ** - * Return the name of first live WINS server in the list. - * - * Input: none. - * - * Output: A pointer to a string containing either the DNS name or IP - * address of the WINS server as given in the WINS SERVER - * parameter in smb.conf, or NULL if no (live) WINS servers are - * in the list. - * - * Notes: This function will return the name of the first available - * NBNS (WINS) server. The order of the list is determined in - * smb.conf. If all of the WINS servers have been marked 'dead' - * then NULL is returned. - * - * - This function does not verify that the name can be mapped to - * an IP address, or that the WINS server is running. - * - * ------------------------------------------------------------------------ ** - */ - { - time_t now = time(NULL); - list_entry *entry = (list_entry *)ubi_slFirst( wins_srv_list ); - - while( NULL != entry ) - { - if( now >= entry->mourning ) - return( entry->server ); /* Found a live one. */ - entry = (list_entry *)ubi_slNext( entry ); - } - - /* If there are no live entries, return NULL. */ - return( NULL ); - } /* wins_srv_name */ - - -void wins_srv_died( struct in_addr boothill_ip ) - /* ------------------------------------------------------------------------ ** - * Called to indicate that a specific WINS server has died. - * - * Input: boothill_ip - IP address of an NBNS (WINS) server that has - * failed. - * - * Notes: This function marks the record 'dead' for NECROMANCYCLE - * seconds. - * - * ------------------------------------------------------------------------ ** - */ - { - list_entry *entry; +/* + see if an ip is on the dead list +*/ +static int wins_is_dead(struct in_addr ip) +{ + struct wins_dead *d; + for (d=dead_servers; d; d=d->next) { + if (ip_equal(ip, d->ip)) { + /* it might be due for revival */ + if (d->revival <= time(NULL)) { + DEBUG(4,("Reviving wins server %s\n", inet_ntoa(ip))); + DLIST_REMOVE(dead_servers, d); + free(d); + return 0; + } + return 1; + } + } + return 0; +} - if( is_zero_ip( boothill_ip ) ) - { - DEBUG( 4, ("wins_srv_died(): Invalid request to mark zero IP down.\n") ); - return; - } +/* + mark a wins server as temporarily dead +*/ +void wins_srv_died(struct in_addr ip) +{ + struct wins_dead *d; - entry = (list_entry *)ubi_slFirst( wins_srv_list ); - while( NULL != entry ) - { - /* Match based on IP. */ - if( ip_equal( boothill_ip, entry->ip_addr ) ) - { - entry->mourning = time(NULL) + NECROMANCYCLE; - entry->ip_addr.s_addr = 0; /* Force a re-lookup at re-birth. */ - DEBUG( 2, ( "wins_srv_died(): WINS server %s appears to be down.\n", - entry->server ) ); - return; - } - entry = (list_entry *)ubi_slNext( entry ); - } + if (is_zero_ip(ip) || wins_is_dead(ip)) { + return; + } - if( DEBUGLVL( 1 ) ) - { - dbgtext( "wins_srv_died(): Could not mark WINS server %s down.\n", - inet_ntoa( boothill_ip ) ); - dbgtext( "Address not found in server list.\n" ); - } - } /* wins_srv_died */ + d = (struct wins_dead *)malloc(sizeof(*d)); + if (!d) return; + d->ip = ip; + d->revival = time(NULL) + DEATH_TIME; -unsigned long wins_srv_count( void ) - /* ------------------------------------------------------------------------ ** - * Return the total number of entries in the list, dead or alive. - * ------------------------------------------------------------------------ ** - */ - { - unsigned long count = ubi_slCount( wins_srv_list ); + DEBUG(4,("Marking wins server %s dead for %u seconds\n", inet_ntoa(ip), DEATH_TIME)); - if( DEBUGLVL( 8 ) ) - { - list_entry *entry = (list_entry *)ubi_slFirst( wins_srv_list ); - time_t now = time(NULL); + DLIST_ADD(dead_servers, d); +} - dbgtext( "wins_srv_count: WINS status: %ld servers.\n", count ); - while( NULL != entry ) - { - dbgtext( " %s <%s>: ", entry->server, inet_ntoa( entry->ip_addr ) ); - if( now >= entry->mourning ) - dbgtext( "alive\n" ); - else - dbgtext( "dead for %d more seconds\n", (int)(entry->mourning - now) ); +/* + return the total number of wins servers, dead or not +*/ +unsigned long wins_srv_count(void) +{ + char **list; + int count = 0; - entry = (list_entry *)ubi_slNext( entry ); - } - } + list = lp_wins_server_list(); + while (list && *list) { + count++; + list++; + } - return( count ); - } /* wins_srv_count */ + DEBUG(6,("Found %u wins servers in list\n", count)); + return count; +} -/* ========================================================================== */ +/* + return the IP of the currently active wins server, or the zero IP otherwise +*/ +struct in_addr wins_srv_ip(void) +{ + char **list; + struct in_addr ip; + + list = lp_wins_server_list(); + if (!list || !*list) { + zero_ip(&ip); + return ip; + } + + /* find the first live one */ + while (list && *list) { + ip = *interpret_addr2(*list); + if (!wins_is_dead(ip)) { + DEBUG(6,("Current wins server is %s\n", inet_ntoa(ip))); + return ip; + } + list++; + } + + /* damn, they are all dead. Keep trying the primary until they revive */ + list = lp_wins_server_list(); + ip = *interpret_addr2(list[0]); + + return ip; +} |