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diff --git a/source/namework.doc b/source/namework.doc deleted file mode 100644 index 958a86c8668..00000000000 --- a/source/namework.doc +++ /dev/null @@ -1,363 +0,0 @@ -/* - Unix SMB/Netbios documentation. - Version 0.1 - Copyright (C) Luke Leighton Andrew Tridgell 1996 - - This program is free software; you can redistribute it and/or modify - it under the terms of the GNU General Public License as published by - the Free Software Foundation; either version 2 of the License, or - (at your option) any later version. - - This program is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - GNU General Public License for more details. - - You should have received a copy of the GNU General Public License - along with this program; if not, write to the Free Software - Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. - - Document name: namework.doc - - Revision History: - - 0.0 - 02jul96 : lkcl@pires.co.uk - created - - 0.1 - 22jul96 Andrew.Tridgell@anu.edu.au - tridge's comments on first revision -*/ - -the module namework.c deals with NetBIOS datagram packets, primarily. -it deals with nmbd's workgroup browser side and the domain log in -side. none of the functionality here has specification documents available. -empirical observation of packet traces has been the order of the day, -along with some guess-work. - -beware! - -the receipt of datagram packets for workgroup browsing are dealt with here. -some of the functions listed here will call others outside of this -module, or will activate functionality dealt with by other modules -(namedb, nameannounce, nameelect, namelogon, and namebrowse). - - -/************************************************************************* - process_browse_packet() - *************************************************************************/ - -this function is responsible for further identifying which type of -browser datagram packet has been received, and dealing with it -accordingly. if the packet is not dealt with, then an error is -logged along with the type of packet that has been received. - -if listening_type() was in use, then it would be used here. - -the types of packets received and dealt with are: - -- ANN_HostAnnouncement -- ANN_DomainAnnouncement -- ANN_LocalMasterAnnouncement - -these are all identical in format and can all be processed by -process_announce(). an announcement is received from a host -(either a master browser telling us about itself, a server -telling us about itself or a master browser telling us about -a domain / workgroup) - -- ANN_AnnouncementRequest - -these are sent by master browsers or by servers. it is a -request to announce ourselves as appropriate by sending -either a ANN_HostAnnouncement datagram or both an -ANN_DomainAnnouncement and an ANN_LocalMasterAnnouncement -if we are a master browser (but not both). - -- ANN_Election - -this is an election datagram. if samba has been configured -as a domain master then it will also send out election -datagrams. - -- ANN_GetBackupListReq - -this is a request from another server for us to send a -backup list of all servers that we know about. we respond -by sending a datagram ANN_GetBackupListResp. the protocol -here is a little dicey. - -- ANN_GetBackupListResp - -this is a response from another server that we have sent an -ANN_GetBackupListReq to. the protocol is a little dicey. - -- ANN_BecomeBackup - -this is a message sent by a master browser to a -potential master browser, indicating that it should become -a backup master browser for the workgroup it is a member -of. samba does not respond at present to such datagrams, -and it also sends out such datagrams for the wrong reasons -(this code has now been disabled until this is fixed). - -- ANN_ResetBrowserState - -this datagram is sent for trouble-shooting purposes. -it asks a browser to clear out its server lists, or to -stop becoming a master browser altogether. NT/AS and -samba do not implement this latter option. - -- ANN_MasterAnnouncement - -this datagram is sent by a master browser to a domain master -browser. it is a way to ensure that master browsers are kept in sync -with a domain master browser across a wide area network. on -receipt of an ANN_MasterAnnouncement we should sync browse lists with -the sender. - -(i never got the hang of this one when i was experimenting. -i forget exactly what it's for, and i never fully worked -out how to coax a server to send it. :-) - -NOTE FROM TRIDGE: The reason you didn't work out how to coax a server -into sending it is that you can't (or shouldn't try!). Basically these -"master announce" datagrams are the way that separate netbios subnets -are linked together to form a complete browse net. The way it works is -that the local master decides it is going to inform the domain master -of its presence, then sends this master announce to the domain -master. The domain master then syncs with the local master using a -"local only" sync. The whole transaction is initiated by the local -master, not the domain master, so the domain master should not do any -of this if it does not first receive a "master announcement". The -local domain masters need to be configured to know the IP address of -the domain master. - - -/************************************************************************* - listening_type() - *************************************************************************/ - - -a datagram packet is sent from one NetBIOS name of a specific type -to another NetBIOS name of a specific type. certain types of -datagrams are only expected from certain types of NetBIOS names. - -this function is intended to catch errors in the type of datagrams -received from different NetBIOS names. it is currently incomplete -due to lack of information on the types of names and the datagrams -they send. - - -/************************************************************************* - process_announce_request() - *************************************************************************/ - -this function is responsible for dealing with announcement requests. -if the type of name that the request is sent to matches our current -status, then we should respond. otherwise, the datagram should be -ignored. - -samba only responds on its local subnets. - -at present, just the name is checked to see if the packet is for us. -what should be done is that if we own the name (e.g WORGROUP(0x1d) -or WORKGROUP(0x1b) then we should respond, otherwise, ignore the -datagram. - -if the name is for us, and we are a member of that workgroup, then -samba should respond. - -note that samba does not respond immediately. this is to ensure that -if the master browser for the workgroup that samba is a member of -sends out a broadcast request announcement, that that master browser -is not swamped with replies. it is therefore up to samba to reply -at some random interval. hence, a flag is set indicating the need -to announce later. - - -/************************************************************************* - process_reset_browser() - *************************************************************************/ - -this function is responsible for dealing with reset state datagrams. -there are three kinds of diagnostic reset requests: - -- stop being a master browser -- discard browse lists, stop being a master browser, and run for re-election -- stop being a master browser forever. - -samba and windows nt do not implement the latter option. - -there appears to be a discrepancy between this description and the -code actually implemented. - - -/************************************************************************* - process_send_backup_list() - *************************************************************************/ - -this function is part of samba's domain master browser functionality. - -it is responsible for giving master browsers a list of other browsers -that maintain backup lists of servers for that master browser's workgroup. - -it is also responsible for giving master browsers a list of domain master -browsers for that local master browser's domain. - -a correct way to think of this function is that it is a 'request to -send out a backup list for the requested workgroup or domain'. - -i have some suspicions and intuitions about this function and how it -is to actually be used. there is no documentation on this, so it is a -matter of experimenting until it's right. - - -/************************************************************************* - send_backup_list() - *************************************************************************/ - -this function is responsible for compiling a list of either master -browsers and backup master browsers or domain master browsers and -backup domain master browsers. samba constructs this list from its -workgroup / server database. - -the list is then sent to the host that requested it by sending an -ANN_GetBackupListResp datagram to this host. - - -NOTE FROM TRIDGE: The "backup list" stuff is only relevant to -local subnets. It has nothing to do with PDCs or domain masters. Its -function is twofold: - -1) spread the browsing load over multiple servers so one server -doesn't get overloaded with browse requests -2) make sure the database doesn't get lost completely if the master -goes down - -To accomplish this a few things are supposed to be done: - -- the master browser maintains a list of "backup browsers". - -- backup browsers are are machines that are just like ordinary servers -but also maintain a browse list and respond to "NetServerEnum" -requests - -- when a server initially announces itself to the master it may set -its "maintain browse list" flag to auto. - -- when a master browser sees a server announcement with "auto" set it -may send a "become backup" to that server telling it to become a -backup. - -- the master has a simple algorithm to determine how many backups it wants -given the number of hosts on the net - -- when a client wishes to get a browse list it asks the master for a -backup list. The master sends it the current list of backup browsers, -including itself. The client caches this list. The client then sends -the NetServerEnum to a random member of this list easch time it wants -to browse. This spreads the load. - - - -/************************************************************************* - process_rcv_backup_list() - *************************************************************************/ - -this function is implemented with a slightly over-kill algorithm. -the correct functionality is to pick any three names at random from -the list that is received from this datagram, and then at intervals -contact _one_ of them for a list of browser, in order to update -samba's browse list. - -samba contacts every single one of the backup browsers listed, through -the use of a NAME_QUERY_SRV_CHK 'state'. - - -/************************************************************************* - process_master_announce() - *************************************************************************/ - -this function is responsible for synchronising browse lists with a -master browser that contacts samba in its capacity as a domain master -browser. - -the function add_browser_entry() is used to add the server that -contacts us to our list of browser to sync browse lists with at -some point in the near future. - - -/************************************************************************* - process_announce() - *************************************************************************/ - -this function is responsible for dealing with the three types of -announcement type datagrams that samba recognises. some appropriate -type-checking is done on the name that the datagram is sent to. - -samba does not at present deal with LanManager announcements. - -these announcements are for updating the browse entry records. -each browse entry has a time-to-live associated with it. each server -must refresh its entry with all other servers by broadcasting -Announcements. if it does not do so, then other servers will not -know about that machine, and the records on each server of that -other machine will die. - -if an ANN_DomainAnnouncement is received, then this will be from -a master browser. only one machine on any given broadcast area (e.g -a subnet) should be broadcasting such announcements. the information -it contains tells other servers that there is a master browser for -this workgroup. if another server thinks that it is also a master -browser for the same workgroup, then it should stop being a master -browser and force an election. - -if an ANN_LocalMasterAnnouncement is received, then a master browser -is telling us that it exists. i am uncertain that anything else -actually needs to be done with this, other than to shout 'hooray' and -'thank you for informing me of this fact'. - - -/************************************************************************* - listening_name() - *************************************************************************/ - -this function is an over-simplified way of identifying whether we -should be responding to a datagram that has been received. - - -/************************************************************************* - same_context() - *************************************************************************/ - -this function helps us to identify whether we should be responding to -a datagram that has been received. - - -/************************************************************************* - tell_become_backup() - *************************************************************************/ - -this function is part of samba's domain master browser capabilities. -it is responsible for finding appropriate servers to tell to become a -backup master browser for the domain that samba controls. - -other servers that contact samba asking for a list of backup browsers -will then be given that server's name, and that server can expect to -receive NetServerEnum requests for lists of servers and workgroups. - -this function must be updated before it is in a fit state to be used. -it must properly check whether a server is prepared to become a backup -browser before actually asking it to be one. - - -/************************************************************************* - reset_server() - *************************************************************************/ - -this function is responsible for issuing an ANN_ResetBrowserState to -the specified server, asking it to reset its browser information. - -see process_reset_browser() for details on this function. - - |