[LON-CAPA-cvs] cvs: loncom / lond
harris41
lon-capa-cvs@mail.lon-capa.org
Sun, 03 Mar 2002 19:49:01 -0000
harris41 Sun Mar 3 14:49:01 2002 EDT
Modified files:
/loncom lond
Log:
up to date, fairly complete documentation
Index: loncom/lond
diff -u loncom/lond:1.73 loncom/lond:1.74
--- loncom/lond:1.73 Mon Feb 25 15:43:15 2002
+++ loncom/lond Sun Mar 3 14:49:00 2002
@@ -2,7 +2,7 @@
# The LearningOnline Network
# lond "LON Daemon" Server (port "LOND" 5663)
#
-# $Id: lond,v 1.73 2002/02/25 20:43:15 www Exp $
+# $Id: lond,v 1.74 2002/03/03 19:49:00 harris41 Exp $
#
# Copyright Michigan State University Board of Trustees
#
@@ -1446,16 +1446,284 @@
=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
+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.
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
@@ -1480,11 +1748,3 @@
Server/Process
=cut
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