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Diff for /loncom/lond between versions 1.73 and 1.74

version 1.73, 2002/02/25 20:43:15 version 1.74, 2002/03/03 19:49:00
Line 1446  lond - "LON Daemon" Server (port "LOND" Line 1446  lond - "LON Daemon" Server (port "LOND"
   
 =head1 SYNOPSIS  =head1 SYNOPSIS
   
 Should only be run as user=www.  Invoked by loncron.  Usage: B<lond>
   
   Should only be run as user=www.  This is a command-line script which
   is invoked by B<loncron>.  There is no expectation that a typical user
   will manually start B<lond> from the command-line.  (In other words,
   DO NOT START B<lond> YOURSELF.)
   
 =head1 DESCRIPTION  =head1 DESCRIPTION
   
   There are two characteristics associated with the running of B<lond>,
   PROCESS MANAGEMENT (starting, stopping, handling child processes)
   and SERVER-SIDE ACTIVITIES (password authentication, user creation,
   subscriptions, etc).  These are described in two large
   sections below.
   
   B<PROCESS MANAGEMENT>
   
 Preforker - server who forks first. Runs as a daemon. HUPs.  Preforker - server who forks first. Runs as a daemon. HUPs.
 Uses IDEA encryption  Uses IDEA encryption
   
 =head1 README  B<lond> forks off children processes that correspond to the other servers
   in the network.  Management of these processes can be done at the
   parent process level or the child process level.
   
   B<logs/lond.log> is the location of log messages.
   
   The process management is now explained in terms of linux shell commands,
   subroutines internal to this code, and signal assignments:
   
   =over 4
   
   =item *
   
   PID is stored in B<logs/lond.pid>
   
   This is the process id number of the parent B<lond> process.
   
   =item *
   
   SIGTERM and SIGINT
   
   Parent signal assignment:
    $SIG{INT}  = $SIG{TERM} = \&HUNTSMAN;
   
   Child signal assignment:
    $SIG{INT}  = 'DEFAULT'; (and SIGTERM is DEFAULT also)
   (The child dies and a SIGALRM is sent to parent, awaking parent from slumber
    to restart a new child.)
   
   Command-line invocations:
    B<kill> B<-s> SIGTERM I<PID>
    B<kill> B<-s> SIGINT I<PID>
   
   Subroutine B<HUNTSMAN>:
    This is only invoked for the B<lond> parent I<PID>.
   This kills all the children, and then the parent.
   The B<lonc.pid> file is cleared.
   
   =item *
   
   SIGHUP
   
   Current bug:
    This signal can only be processed the first time
   on the parent process.  Subsequent SIGHUP signals
   have no effect.
   
   Parent signal assignment:
    $SIG{HUP}  = \&HUPSMAN;
   
   Child signal assignment:
    none (nothing happens)
   
   Command-line invocations:
    B<kill> B<-s> SIGHUP I<PID>
   
   Subroutine B<HUPSMAN>:
    This is only invoked for the B<lond> parent I<PID>,
   This kills all the children, and then the parent.
   The B<lond.pid> file is cleared.
   
   =item *
   
   SIGUSR1
   
   Parent signal assignment:
    $SIG{USR1} = \&USRMAN;
   
   Child signal assignment:
    $SIG{USR1}= \&logstatus;
   
   Command-line invocations:
    B<kill> B<-s> SIGUSR1 I<PID>
   
   Subroutine B<USRMAN>:
    When invoked for the B<lond> parent I<PID>,
   SIGUSR1 is sent to all the children, and the status of
   each connection is logged.
   
   =item *
   
   SIGCHLD
   
   Parent signal assignment:
    $SIG{CHLD} = \&REAPER;
   
   Child signal assignment:
    none
   
   Command-line invocations:
    B<kill> B<-s> SIGCHLD I<PID>
   
   Subroutine B<REAPER>:
    This is only invoked for the B<lond> parent I<PID>.
   Information pertaining to the child is removed.
   The socket port is cleaned up.
   
   =back
   
   B<SERVER-SIDE ACTIVITIES>
   
   Server-side information can be accepted in an encrypted or non-encrypted
   method.
   
   =over 4
   
   =item ping
   
   Query a client in the hosts.tab table; "Are you there?"
   
   =item pong
   
   Respond to a ping query.
   
   =item ekey
   
   Read in encrypted key, make cipher.  Respond with a buildkey.
   
   =item load
   
   Respond with CPU load based on a computation upon /proc/loadavg.
   
   =item currentauth
   
   Reply with current authentication information (only over an
   encrypted channel).
   
   =item auth
   
   Only over an encrypted channel, reply as to whether a user's
   authentication information can be validated.
   
   =item passwd
   
   Allow for a password to be set.
   
   =item makeuser
   
   Make a user.
   
   =item passwd
   
   Allow for authentication mechanism and password to be changed.
   
   =item home
   
 Not yet written.  Respond to a question "are you the home for a given user?"
   
   =item update
   
   Update contents of a subscribed resource.
   
   =item unsubscribe
   
   The server is unsubscribing from a resource.
   
   =item subscribe
   
   The server is subscribing to a resource.
   
   =item log
   
   Place in B<logs/lond.log>
   
   =item put
   
   stores hash in namespace
   
   =item rolesput
   
   put a role into a user's environment
   
   =item get
   
   returns hash with keys from array
   reference filled in from namespace
   
   =item eget
   
   returns hash with keys from array
   reference filled in from namesp (encrypts the return communication)
   
   =item rolesget
   
   get a role from a user's environment
   
   =item del
   
   deletes keys out of array from namespace
   
   =item keys
   
   returns namespace keys
   
   =item dump
   
   dumps the complete (or key matching regexp) namespace into a hash
   
   =item store
   
   stores hash permanently
   for this url; hashref needs to be given and should be a \%hashname; the
   remaining args aren't required and if they aren't passed or are '' they will
   be derived from the ENV
   
   =item restore
   
   returns a hash for a given url
   
   =item querysend
   
   Tells client about the lonsql process that has been launched in response
   to a sent query.
   
   =item queryreply
   
   Accept information from lonsql and make appropriate storage in temporary
   file space.
   
   =item idput
   
   Defines usernames as corresponding to IDs.  (These "IDs" are unique identifiers
   for each student, defined perhaps by the institutional Registrar.)
   
   =item idget
   
   Returns usernames corresponding to IDs.  (These "IDs" are unique identifiers
   for each student, defined perhaps by the institutional Registrar.)
   
   =item tmpput
   
   Accept and store information in temporary space.
   
   =item tmpget
   
   Send along temporarily stored information.
   
   =item ls
   
   List part of a user's directory.
   
   =item Hanging up (exit or init)
   
   What to do when a client tells the server that they (the client)
   are leaving the network.
   
   =item unknown command
   
   If B<lond> is sent an unknown command (not in the list above),
   it replys to the client "unknown_cmd".
   
   =item UNKNOWN CLIENT
   
   If the anti-spoofing algorithm cannot verify the client,
   the client is rejected (with a "refused" message sent
   to the client, and the connection is closed.
   
   =back
   
 =head1 PREREQUISITES  =head1 PREREQUISITES
   
Line 1480  linux Line 1748  linux
 Server/Process  Server/Process
   
 =cut  =cut
   
   
   
   
   
   
   
   
Removed from v.1.73  
changed lines
  Added in v.1.74

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