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Diffstat (limited to 'source/nameelect.doc')
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diff --git a/source/nameelect.doc b/source/nameelect.doc deleted file mode 100644 index df025e2069a..00000000000 --- a/source/nameelect.doc +++ /dev/null @@ -1,256 +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: nameelect.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 nameelect.c deals with initiating, winning, losing -browsing elections, and checking if browsers are still around, -and the consequences of getting involved in all this. - -an election packet can be received at any time, which will initiate -an election. samba can also detect that there is no longer a -master browser and will initiate an election. - -there is one way to become a master browser, but there are two -ways to un-become a master browser. if you lose an election, you -must stop being a master browser. if you fail to register your -unique special browser names (either on your local subnet or with -the WINS server) then you must stop being a master browser. - -this is a double fail-safe mechanism to ensure that there is only -one master browser per workgroup per subnet (and one domain master -browser - per domain (workgroup) per wide area network). - -(a wide area network is created when one or more servers on a -broadcast-isolated subnet point to the same WINS server). - --------- -NOTE FROM TRIDGE: - -I'd say "domain master browser" not "WINS server" here. WINS doesn't -have much to do with browsing, it is the WAN varient of name -resolution. The name resolution and browsing functions of a netbios -network are almost entirely separate. Both grew out of systems that -could only be used on local networks. - -To adapt them to WANs, WINS was added for name resolution, and "domain -master browsers" were added for browse lists. It would be perfectly -possible to have a WINS server that doesn't even listen to UDP port -138. --------- - -/************************************************************************* - check_elections() - *************************************************************************/ - -this function returns True if samba is in the process of running an -election on any of its interfaces. a better version of this function -should return the time-out period in between election packets, in -milliseconds. - - -/************************************************************************* - process_election() - *************************************************************************/ - -this function is responsible for dealing with the receipt of an election -browse MAILSLOT packet. - -if samba is running an election, it checks the criteria in the packet -received using win_election() to see if it has lost the election or if -it should join in the election. - -if it loses the election, then it becomes a non-master. - - -/************************************************************************* - win_election() - *************************************************************************/ - -this function returns True if samba has won an election. the criteria -in order of precedence are: - -the election version; the election criteria; the time since samba was -started; and as a last resort, a name comparison is used. - - -/************************************************************************* - run_elections() - *************************************************************************/ - -this function is responsible for sending out election packets if -samba is running in an election. once the fourth packet is sent -out, it is assumed that we have won, and samba initiates becoming -a master browser. - -(it looks like samba sends out an extra packet just to be sure...) - - -/************************************************************************* - become_nonmaster() - *************************************************************************/ - -this function is responsible for down-grading samba's status from -either domain master to master browser or nothing, or master browser -to nothing, depending on its current status. - -samba can become a non-master in three ways: by losing an election - -see process_election(); by having one of its special browser names -de-registered - see name_unregister_work(); by receiving and -processing a browser reset packet - see process_reset_browser(). - -when samba stops being a domain master, it must release its unique -0x1b name. when samba stops being a master browser, it must release -its unique 0x1d name. - -becoming non-master is done on a per-subnet basis. - - -/************************************************************************* - become_master() - *************************************************************************/ - -this function is responsible for slowly turning samba into a -local master browser or a domain master browser. - - -this is done in stages. note that this could take a while, -particularly on a broadcast subnet, as we have to wait for -the implicit registration of each name to be accepted. - -as each name is successfully registered, become_master() is -called again via name_register_work(), in order to initiate -the next stage (see dead_netbios_entry() - deals with implicit -name registration and response_name_reg() - deals with explicit -registration with a WINS server). - -stage 1: was MST_NONE - go to MST_NONE and register ^1^2__MSBROWSE__^2^1. -stage 2: was MST_WON - go to MST_MSB and register WORKGROUP(0x1d) -stage 3: was MST_MSB - go to MST_BROWSER and register WORKGROUP(0x1b) -stage 4: was MST_BROWSER - go to MST_DOMAIN (do not pass GO, do not...) - -note that this code still does not cope with the distinction -between different types of nodes, particularly between M and P -nodes (see rfc1001.txt). that will be developed later. - - -/************************************************************************* - name_register_work() - *************************************************************************/ - -this function is called when a NetBIOS name is successfully -registered. it will add the registered name into samba's NetBIOS -records. - -it has the additional responsibility that when samba is becoming -a master browser, it must initiate the next stage in the progress -towards becoming a master browser. - -implicit name registration is done through dead_netbios_entry() -by time-out. explicit name registration is done through -response_name_reg() with a WINS server. - - -/************************************************************************* - name_unregister_work() - *************************************************************************/ - -this function is called when there is an objection to a NetBIOS -name being registered. this will always be done through a negative -response to a name registration, whether it be by a host that -already owns the unique name being registered on a subnet, or -by a WINS server. - -the name being objected to must be removed from samba's records. - -it has the additional responsibility of checking whether samba is -currently a master browser or not, and if so it should initiate -becoming a non-master. - - - -/************************************************************************* - send_election() - *************************************************************************/ - -this function is responsible for sending a browse mailslot -datagram election packet (of type ANN_Election). it constructs -the packet with all the relevant info needed to participate: -election version; election criteria; time since startup and -our name. - -this function can be used to ensure that initiate but lose an -election by specifying a criteria and time up of zero. this -is necessary if we are a master browser and we are about to -go down (politely!) - see nmbd.c:sig_term(). - - -/************************************************************************* - browser_gone() - *************************************************************************/ - -this function is responsible for dealing with the instance when -the master browser we thought was present on a subnet is no longer -responding. - -if it is samba's workgroup, and it's a local interface, samba -detects that it can participate in an election on that interface -and potentially become a master browser or domain master. - -if it's a local subnet and not one of samba's workgroups, then -samba will force an election (which it is not obliged to do). -remove_workgroup() will be expected to remove all references -to this workgroup and the servers in it from the database. - -if it's a remote subnet and not one of samba's workgroups then -no election is forced, and remove_workgroup() will be expected -to remove all server entries from this workgroup _except_ those -added from the lmhosts file. if there are entries added from -the lmhosts file, then the workgroup entry will remain, -otherwise it too will be removed. - - -/************************************************************************* - check_master_browser() - *************************************************************************/ - -this function is responsible for periodically checking whether -master browsers that samba expects to be alive are alive. this -is done every CHECK_TIME_MST_BROWSE minutes. - -for every workgroup record for which samba is not a master browser, -on both local and remote interfaces, samba will initiate a -broadcast query for a master browser on that subnet. - -(browser_gone() will be called to deal with the case where no -response is received to the NAME_QUERY_MST_CHK initiated here. -no action is required when a response _is_ received, however: -see nameservresp.c:response_process() and dead_netbios_entry() -for details) - - |