diff options
Diffstat (limited to 'source3/lib/wins_srv.c')
| -rw-r--r-- | source3/lib/wins_srv.c | 647 |
1 files changed, 329 insertions, 318 deletions
diff --git a/source3/lib/wins_srv.c b/source3/lib/wins_srv.c index 0181ee0956..adf405ae7e 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 + Samba wins server helper functions + 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 +21,330 @@ #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. - */ - -#define NECROMANCYCLE 600 /* 600 seconds == 10 minutes. */ - -/* -------------------------------------------------------------------------- ** - * 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; - - if( is_zero_ip( boothill_ip ) ) - { - DEBUG( 4, ("wins_srv_died(): Invalid request to mark zero IP down.\n") ); - return; - } - - 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( 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 */ - - -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 ); - - if( DEBUGLVL( 8 ) ) - { - list_entry *entry = (list_entry *)ubi_slFirst( wins_srv_list ); - time_t now = time(NULL); - - 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) ); - - entry = (list_entry *)ubi_slNext( entry ); - } - } - - return( count ); - } /* wins_srv_count */ - -/* ========================================================================== */ +/* + this is pretty much a complete rewrite of the earlier code. The main + aim of the rewrite is to add support for having multiple wins server + lists, so Samba can register with multiple groups of wins servers + and each group has a failover list of wins servers. + + Central to the way it all works is the idea of a wins server + 'tag'. A wins tag is a label for a group of wins servers. For + example if you use + + wins server = fred:192.168.2.10 mary:192.168.3.199 fred:192.168.2.61 + + then you would have two groups of wins servers, one tagged with the + name 'fred' and the other with the name 'mary'. I would usually + recommend using interface names instead of 'fred' and 'mary' but + they can be any alpha string. + + Now, how does it all work. Well, nmbd needs to register each of its + IPs with each of its names once with each group of wins servers. So + it tries registering with the first one mentioned in the list, then + if that fails it marks that WINS server dead and moves onto the next + one. + + In the client code things are a bit different. As each of the groups + of wins servers is a separate name space we need to try each of the + groups until we either succeed or we run out of wins servers to + try. If we get a negative response from a wins server then that + means the name doesn't exist in that group, so we give up on that + group and move to the next group. If we don't get a response at all + then maybe the wins server is down, in which case we need to + failover to the next one for that group. + + confused yet? (tridge) +*/ + + +/* how long a server is marked dead for */ +#define DEATH_TIME 600 + +/* a list of wins server that are marked dead from the point of view + of a given source address. We keep a separate dead list for each src address + to cope with multiple interfaces that are not routable to each other + */ +static struct wins_dead { + struct in_addr dest_ip; + struct in_addr src_ip; + time_t revival; /* when it will be revived */ + struct wins_dead *next, *prev; +} *dead_servers; + +/* an internal convenience structure for an IP with a short string tag + attached */ +struct tagged_ip { + fstring tag; + struct in_addr ip; +}; + +/* + see if an ip is on the dead list +*/ +BOOL wins_srv_is_dead(struct in_addr wins_ip, struct in_addr src_ip) +{ + struct wins_dead *d; + for (d=dead_servers; d; d=d->next) { + if (ip_equal(wins_ip, d->dest_ip) && ip_equal(src_ip, d->src_ip)) { + /* it might be due for revival */ + if (d->revival <= time(NULL)) { + fstring src_name; + fstrcpy(src_name, inet_ntoa(src_ip)); + DEBUG(4,("Reviving wins server %s for source %s\n", + inet_ntoa(wins_ip), src_name)); + DLIST_REMOVE(dead_servers, d); + free(d); + return False; + } + return True; + } + } + return False; +} + + +/* + mark a wins server as being alive (for the moment) +*/ +void wins_srv_alive(struct in_addr wins_ip, struct in_addr src_ip) +{ + struct wins_dead *d; + for (d=dead_servers; d; d=d->next) { + if (ip_equal(wins_ip, d->dest_ip) && ip_equal(src_ip, d->src_ip)) { + fstring src_name; + fstrcpy(src_name, inet_ntoa(src_ip)); + DEBUG(4,("Reviving wins server %s for source %s\n", + inet_ntoa(wins_ip), src_name)); + DLIST_REMOVE(dead_servers, d); + return; + } + } +} + + +/* + mark a wins server as temporarily dead +*/ +void wins_srv_died(struct in_addr wins_ip, struct in_addr src_ip) +{ + struct wins_dead *d; + fstring src_name; + + if (is_zero_ip(wins_ip) || wins_srv_is_dead(wins_ip, src_ip)) { + return; + } + + d = (struct wins_dead *)malloc(sizeof(*d)); + if (!d) return; + + d->dest_ip = wins_ip; + d->src_ip = src_ip; + d->revival = time(NULL) + DEATH_TIME; + + fstrcpy(src_name, inet_ntoa(src_ip)); + + DEBUG(4,("Marking wins server %s dead for %u seconds from source %s\n", + inet_ntoa(wins_ip), DEATH_TIME, src_name)); + + DLIST_ADD(dead_servers, d); +} + +/* + return the total number of wins servers, dead or not +*/ +unsigned wins_srv_count(void) +{ + char **list; + int count = 0; + + if (lp_wins_support()) { + /* simple - just talk to ourselves */ + return 1; + } + + list = lp_wins_server_list(); + for (count=0; list && list[count]; count++) /* nop */ ; + + return count; +} + +/* + parse an IP string that might be in tagged format + the result is a tagged_ip structure containing the tag + and the ip in in_addr format. If there is no tag then + use the tag '*' +*/ +static void parse_ip(struct tagged_ip *ip, const char *str) +{ + char *s = strchr(str, ':'); + if (!s) { + fstrcpy(ip->tag, "*"); + ip->ip = *interpret_addr2(str); + return; + } + + ip->ip = *interpret_addr2(s+1); + fstrcpy(ip->tag, str); + s = strchr(ip->tag, ':'); + if (s) *s = 0; +} + + + +/* + return the list of wins server tags. A 'tag' is used to distinguish + wins server as either belonging to the same name space or a separate + name space. Usually you would setup your 'wins server' option to + list one or more wins server per interface and use the interface + name as your tag, but you are free to use any tag you like. +*/ +char **wins_srv_tags(void) +{ + char **ret = NULL; + int count=0, i, j; + char **list; + + if (lp_wins_support()) { + /* give the caller something to chew on. This makes + the rest of the logic simpler (ie. less special cases) */ + ret = (char **)malloc(sizeof(char *)*2); + if (!ret) return NULL; + ret[0] = strdup("*"); + ret[1] = NULL; + return ret; + } + + list = lp_wins_server_list(); + if (!list) return NULL; + + /* yes, this is O(n^2) but n is very small */ + for (i=0;list[i];i++) { + struct tagged_ip t_ip; + + parse_ip(&t_ip, list[i]); + + /* see if we already have it */ + for (j=0;j<count;j++) { + if (strcmp(ret[j], t_ip.tag) == 0) { + break; + } + } + + if (j != count) { + /* we already have it. Move along */ + continue; + } + + /* add it to the list */ + ret = (char **)Realloc(ret, (count+1) * sizeof(char *)); + ret[count] = strdup(t_ip.tag); + if (!ret[count]) break; + count++; + } + + if (count) { + /* make sure we null terminate */ + ret[count] = NULL; + } + + return ret; +} + +/* free a list of wins server tags given by wins_srv_tags */ +void wins_srv_tags_free(char **list) +{ + int i; + if (!list) return; + for (i=0; list[i]; i++) { + free(list[i]); + } + free(list); +} + + +/* + return the IP of the currently active wins server for the given tag, + or the zero IP otherwise +*/ +struct in_addr wins_srv_ip_tag(const char *tag, struct in_addr src_ip) +{ + char **list; + int i; + struct tagged_ip t_ip; + + /* if we are a wins server then we always just talk to ourselves */ + if (lp_wins_support()) { + extern struct in_addr loopback_ip; + return loopback_ip; + } + + list = lp_wins_server_list(); + if (!list || !list[0]) { + struct in_addr ip; + zero_ip(&ip); + return ip; + } + + /* find the first live one for this tag */ + for (i=0; list[i]; i++) { + parse_ip(&t_ip, list[i]); + if (strcmp(tag, t_ip.tag) != 0) { + /* not for the right tag. Move along */ + continue; + } + if (!wins_srv_is_dead(t_ip.ip, src_ip)) { + fstring src_name; + fstrcpy(src_name, inet_ntoa(src_ip)); + DEBUG(6,("Current wins server for tag '%s' with source %s is %s\n", + tag, + src_name, + inet_ntoa(t_ip.ip))); + return t_ip.ip; + } + } + + /* they're all dead - try the first one until they revive */ + for (i=0; list[i]; i++) { + parse_ip(&t_ip, list[i]); + if (strcmp(tag, t_ip.tag) != 0) { + continue; + } + return t_ip.ip; + } + + /* this can't happen?? */ + zero_ip(&t_ip.ip); + return t_ip.ip; +} + + +/* + return a count of the number of IPs for a particular tag, including + dead ones +*/ +unsigned wins_srv_count_tag(const char *tag) +{ + char **list; + int i, count=0; + + /* if we are a wins server then we always just talk to ourselves */ + if (lp_wins_support()) { + return 1; + } + + list = lp_wins_server_list(); + if (!list || !list[0]) { + return 0; + } + + /* find the first live one for this tag */ + for (i=0; list[i]; i++) { + struct tagged_ip t_ip; + parse_ip(&t_ip, list[i]); + if (strcmp(tag, t_ip.tag) == 0) { + count++; + } + } + + return count; +} |