1: #!/usr/bin/perl
2: # The LearningOnline Network with CAPA
3: # lonc maintains the connections to remote computers
4: #
5: # $Id: loncnew,v 1.2 2003/04/18 02:59:31 albertel Exp $
6: #
7: # Copyright Michigan State University Board of Trustees
8: #
9: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
10: #
11: # LON-CAPA is free software; you can redistribute it and/or modify
12: # it under the terms of the GNU General Public License as published by
13: # the Free Software Foundation; either version 2 of the License, or
14: # (at your option) any later version.
15: #
16: # LON-CAPA is distributed in the hope that it will be useful,
17: # but WITHOUT ANY WARRANTY; without even the implied warranty of
18: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19: # GNU General Public License for more details.
20: #
21: # You should have received a copy of the GNU General Public License
22: # along with LON-CAPA; if not, write to the Free Software
23: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
24: #
25: # /home/httpd/html/adm/gpl.txt
26: #
27: # http://www.lon-capa.org/
28: #
29: #
30: # new lonc handles n requestors spread out bver m connections to londs.
31: # This module is based on the Event class.
32: # Development iterations:
33: # - Setup basic event loop. (done)
34: # - Add timer dispatch. (done)
35: # - Add ability to accept lonc UNIX domain sockets. (done)
36: # - Add ability to create/negotiate lond connections (done).
37: # - Add general logic for dispatching requests and timeouts.
38: # - Add support for the lonc/lond requests.
39: # - Add logging/status monitoring.
40: # - Add Signal handling - HUP restarts. USR1 status report.
41: # - Add Configuration file I/O
42: # - Add Pending request processing on startup.
43: # - Add management/status request interface.
44:
45: use lib "/home/httpd/lib/perl/";
46: use lib "/home/foxr/newloncapa/types";
47: use Event qw(:DEFAULT );
48: use POSIX qw(:signal_h);
49: use IO::Socket;
50: use IO::Socket::INET;
51: use IO::Socket::UNIX;
52: use Socket;
53: use Crypt::IDEA;
54: use LONCAPA::Queue;
55: use LONCAPA::Stack;
56: use LONCAPA::LondConnection;
57: use LONCAPA::Configuration;
58: use LONCAPA::HashIterator;
59:
60: print "Loncnew starting\n";
61:
62: #
63: # Disable all signals we might receive from outside for now.
64: #
65: $SIG{QUIT} = IGNORE;
66: $SIG{HUP} = IGNORE;
67: $SIG{USR1} = IGNORE;
68: $SIG{INT} = IGNORE;
69: $SIG{CHLD} = IGNORE;
70: $SIG{__DIE__} = IGNORE;
71:
72:
73: # Read the httpd configuration file to get perl variables
74: # normally set in apache modules:
75:
76: my $perlvarref = LONCAPA::Configuration::read_conf('loncapa.conf');
77: my %perlvar = %{$perlvarref};
78:
79: #
80: # parent and shared variables.
81:
82: my %ChildHash; # by pid -> host.
83:
84:
85: my $MaxConnectionCount = 5; # Will get from config later.
86: my $ClientConnection = 0; # Uniquifier for client events.
87:
88: my $DebugLevel = 5;
89: my $IdleTimeout= 3600; # Wait an hour before pruning connections.
90:
91: #
92: # The variables below are only used by the child processes.
93: #
94: my $RemoteHost; # Name of host child is talking to.
95: my $UnixSocketDir= "/home/httpd/sockets";
96: my $IdleConnections = Stack->new(); # Set of idle connections
97: my %ActiveConnections; # Connections to the remote lond.
98: my %ActiveTransactions; # Transactions in flight.
99: my %ActiveClients; # Serial numbers of active clients by socket.
100: my $WorkQueue = Queue->new(); # Queue of pending transactions.
101: my $ClientQueue = Queue->new(); # Queue of clients causing xactinos.
102: my $ConnectionCount = 0;
103:
104:
105: #
106: =pod
107: =head 2 GetPeerName
108: Returns the name of the host that a socket object is connected
109: to.
110: =cut
111:
112: sub GetPeername {
113: my $connection = shift;
114: my $AdrFamily = shift;
115: my $peer = $connection->peername();
116: my $peerport;
117: my $peerip;
118: if($AdrFamily == AF_INET) {
119: ($peerport, $peerip) = sockaddr_in($peer);
120: my $peername = gethostbyaddr($iaddr, $AdrFamily);
121: return $peername;
122: } elsif ($AdrFamily == AF_UNIX) {
123: my $peerfile;
124: ($peerfile) = sockaddr_un($peer);
125: return $peerfile;
126: }
127: }
128: #----------------------------- Timer management ------------------------
129: =pod
130: =head2 Debug
131: Invoked to issue a debug message.
132: =cut
133: sub Debug {
134: my $level = shift;
135: my $message = shift;
136: if ($level <= $DebugLevel) {
137: print $message." host = ".$RemoteHost."\n";
138: }
139: }
140:
141: sub SocketDump {
142: my $level = shift;
143: my $socket= shift;
144: if($level <= $DebugLevel) {
145: $socket->Dump();
146: }
147: }
148: =pod
149: =head2 Tick
150: Invoked each timer tick.
151: =cut
152:
153: sub Tick {
154: my $client;
155: Debug(6, "Tick");
156: Debug(6, " Current connection count: ".$ConnectionCount);
157: foreach $client (keys %ActiveClients) {
158: Debug(7, " Have client: with id: ".$ActiveClients{$client});
159: }
160: }
161:
162: =pod
163: =head2 SetupTimer
164: Sets up a 1 per sec recurring timer event. The event handler is used to:
165:
166: =item Trigger timeouts on communications along active sockets.
167: =item Trigger disconnections of idle sockets.
168:
169:
170: =cut
171:
172: sub SetupTimer {
173: Debug(6, "SetupTimer");
174: Event->timer(interval => 1, debug => 1, cb => \&Tick );
175: }
176: =pod
177: =head2 ServerToIdle
178: This function is called when a connection to the server is
179: ready for more work.
180: If there is work in the Work queue the top element is dequeued
181: and the connection will start to work on it. If the work queue is
182: empty, the connection is pushed on the idle connection stack where
183: it will either get another work unit, or alternatively, if it sits there
184: long enough, it will be shut down and released.
185:
186:
187: =cut
188: sub ServerToIdle {
189: my $Socket = shift; # Get the socket.
190:
191: &Debug(6, "Server to idle");
192:
193: # If there's work to do, start the transaction:
194:
195: $reqdata = $WorkQueue->dequeue();
196: Debug(9, "Queue gave request data: ".$reqdata);
197: unless($reqdata eq undef) {
198: my $unixSocket = $ClientQueue->dequeue();
199: &Debug(6, "Starting new work request");
200: &Debug(7, "Request: ".$reqdata);
201:
202: &StartRequest($Socket, $unixSocket, $reqdata);
203: } else {
204:
205: # There's no work waiting, so push the server to idle list.
206: &Debug(8, "No new work requests, server connection going idle");
207: delete($ActiveTransactions{$Socket});
208: $IdleConnections->push($Socket);
209: }
210: }
211: =pod
212: =head2 ClientWritable
213: Event callback for when a client socket is writable.
214: This callback is established when a transaction reponse is
215: avaiable from lond. The response is forwarded to the unix socket
216: as it becomes writable in this sub.
217: Parameters:
218:
219: =item Event - The event that has been triggered. Event->w->data is
220: the data and Event->w->fd is the socket to write.
221:
222: =cut
223: sub ClientWritable {
224: my $Event = shift;
225: my $Watcher = $Event->w;
226: my $Data = $Watcher->data;
227: my $Socket = $Watcher->fd;
228:
229: # Try to send the data:
230:
231: &Debug(6, "ClientWritable writing".$Data);
232: &Debug(9, "Socket is: ".$Socket);
233:
234: my $result = $Socket->send($Data, 0);
235:
236: # $result undefined: the write failed.
237: # otherwise $result is the number of bytes written.
238: # Remove that preceding string from the data.
239: # If the resulting data is empty, destroy the watcher
240: # and set up a read event handler to accept the next
241: # request.
242:
243: &Debug(9,"Send result is ".$result." Defined: ".defined($result));
244: if(defined($result)) {
245: &Debug(9, "send result was defined");
246: if($result == length($Data)) { # Entire string sent.
247: &Debug(9, "ClientWritable data all written");
248: $Watcher->cancel();
249: #
250: # Set up to read next request from socket:
251:
252: my $descr = sprintf("Connection to lonc client %d",
253: $ActiveClients{$Socket});
254: Event->io(cb => \&ClientRequest,
255: poll => 'r',
256: desc => $descr,
257: data => "",
258: fd => $Socket);
259:
260: } else { # Partial string sent.
261: $Watcher->data(substr($Data, $result));
262: }
263:
264: } else { # Error of some sort...
265:
266: # Some errnos are possible:
267: my $errno = $!;
268: if($errno == POSIX::EWOULDBLOCK ||
269: $errno == POSIX::EAGAIN ||
270: $errno == POSIX::EINTR) {
271: # No action taken?
272: } else { # Unanticipated errno.
273: &Debug(5,"ClientWritable error or peer shutdown".$RemoteHost);
274: $Watcher->cancel; # Stop the watcher.
275: $Socket->shutdown(2); # Kill connection
276: $Socket->close(); # Close the socket.
277: }
278:
279: }
280: }
281:
282: =pod
283: =head2 CompleteTransaction
284: Called when the reply data has been received for a lond
285: transaction. The reply data must now be sent to the
286: ultimate client on the other end of the Unix socket. This is
287: done by setting up a writable event for the socket with the
288: data the reply data.
289: Parameters:
290: =item Socket - Socket on which the lond transaction occured. This
291: is a LondConnection. The data received is in the
292: TransactionReply member.
293: =item Client - Unix domain socket open on the ultimate client.
294:
295: =cut
296: sub CompleteTransaction {
297: &Debug(6,"Complete transaction");
298: my $Socket = shift;
299: my $Client = shift;
300:
301: my $data = $Socket->GetReply(); # Data to send.
302:
303: &Debug(8," Reply was: ".$data);
304: my $Serial = $ActiveClients{$Client};
305: my $desc = sprintf("Connection to lonc client %d",
306: $Serial);
307: Event->io(fd => $Client,
308: poll => "w",
309: desc => $desc,
310: cb => \&ClientWritable,
311: data => $data);
312: }
313:
314:
315: =pod
316: =head2 LondReadable
317: This function is called whenever a lond connection
318: is readable. The action is state dependent:
319:
320: =head3 State = Initialized
321: We''re waiting for the challenge, this is a no-op until the
322: state changes.
323: =head3 State=Challenged
324: The challenge has arrived we need to transition to Writable.
325: The connection must echo the challenge back.
326: =head3 State=ChallengeReplied
327: The challenge has been replied to. The we are receiveing the
328: 'ok' from the partner.
329: =head3 State=RequestingKey
330: The ok has been received and we need to send the request for
331: an encryption key. Transition to writable for that.
332: =head3 State=ReceivingKey
333: The the key has been requested, now we are reading the new key.
334: =head3 State=Idle
335: The encryption key has been negotiated or we have finished
336: reading data from the a transaction. If the callback data has
337: a client as well as the socket iformation, then we are
338: doing a transaction and the data received is relayed to the client
339: before the socket is put on the idle list.
340: =head3 State=SendingRequest
341: I do not think this state can be received here, but if it is,
342: the appropriate thing to do is to transition to writable, and send
343: the request.
344: =head3 State=ReceivingReply
345: We finished sending the request to the server and now transition
346: to readable to receive the reply.
347:
348: The parameter to this function are:
349: The event. Implicit in this is the watcher and its data. The data
350: contains at least the lond connection object and, if a
351: transaction is in progress, the socket attached to the local client.
352:
353:
354: =cut
355: sub LondReadable {
356: my $Event = shift;
357: my $Watcher = $Event->w;
358: my $Socket = $Watcher->data;
359: my $client = undef;
360:
361:
362: my $State = $Socket->GetState(); # All action depends on the state.
363:
364: &Debug(6,"LondReadable called state = ".$State);
365: SocketDump(6, $Socket);
366:
367: if($Socket->Readable() != 0) {
368: # bad return from socket read.
369: }
370: SocketDump(6,$Socket);
371:
372: $State = $Socket->GetState(); # Update in case of transition.
373: &Debug(6, "After read, state is ".$State);
374:
375: if($State eq "Initialized") {
376:
377:
378: } elsif ($State eq "ChallengeReceived") {
379: # The challenge must be echoed back; The state machine
380: # in the connection takes care of setting that up. Just
381: # need to transition to writable:
382:
383: $Watcher->poll("w");
384: $Watcher->cb(\&LondWritable);
385:
386: } elsif ($State eq "ChallengeReplied") {
387:
388:
389: } elsif ($State eq "RequestingKey") {
390: # The ok was received. Now we need to request the key
391: # That requires us to be writable:
392:
393: $Watcher->poll("w");
394: $Watcher->cb(\&LondWritable);
395:
396: } elsif ($State eq "ReceivingKey") {
397:
398: } elsif ($State eq "Idle") {
399: # If necessary, complete a transaction and then go into the
400: # idle queue.
401: if(exists($ActiveTransactions{$Socket})) {
402: Debug(8,"Completing transaction!!");
403: CompleteTransaction($Socket,
404: $ActiveTransactions{$Socket});
405: }
406: $Watcher->cancel();
407: ServerToIdle($Socket); # Next work unit or idle.
408:
409: } elsif ($State eq "SendingRequest") {
410: # We need to be writable for this and probably don't belong
411: # here inthe first place.
412:
413: Deubg(6, "SendingRequest state encountered in readable");
414: $Watcher->poll("w");
415: $Watcher->cb(\&LondWritable);
416:
417: } elsif ($State eq "ReceivingReply") {
418:
419:
420: } else {
421: # Invalid state.
422: Debug(4, "Invalid state in LondReadable");
423: }
424: }
425: =pod
426: =head2 LondWritable
427: This function is called whenever a lond connection
428: becomes writable while there is a writeable monitoring
429: event. The action taken is very state dependent:
430: =head3 State = Connected
431: The connection is in the process of sending the
432: 'init' hailing to the lond on the remote end.
433: The connection object''s Writable member is called.
434: On error, ConnectionError is called to destroy
435: the connection and remove it from the ActiveConnections
436: hash
437: =head3 Initialized
438: 'init' has been sent, writability monitoring is
439: removed and readability monitoring is started
440: with LondReadable as the callback.
441: =head3 ChallengeReceived
442: The connection has received the who are you
443: challenge from the remote system, and is in the
444: process of sending the challenge response.
445: Writable is called.
446: =head3 ChallengeReplied
447: The connection has replied to the initial challenge
448: The we switch to monitoring readability looking
449: for the server to reply with 'ok'.
450: =head3 RequestingKey
451: The connection is in the process of requesting its
452: encryption key. Writable is called.
453: =head3 ReceivingKey
454: The connection has sent the request for a key.
455: Switch to readability monitoring to accept the key
456: =head3 SendingRequest
457: The connection is in the process of sending a
458: request to the server. This request is part of
459: a client transaction. All the states until now
460: represent the client setup protocol. Writable
461: is called.
462: =head3 ReceivingReply
463: The connection has sent a request. Now it must
464: receive a reply. Readability monitoring is
465: requested.
466:
467: This function is an event handler and therefore receives as
468: a parameter the event that has fired. The data for the watcher
469: of this event is a reference to a list of one or two elements,
470: depending on state. The first (and possibly only) element is the
471: socket. The second (present only if a request is in progress)
472: is the socket on which to return a reply to the caller.
473:
474: =cut
475: sub LondWritable {
476: my $Event = shift;
477: my $Watcher = $Event->w;
478: my @data = $Watcher->data;
479: Debug(6,"LondWritable State = ".$State." data has ".@data." elts.\n");
480:
481: my $Socket = $data[0]; # I know there's at least a socket.
482:
483: # Figure out what to do depending on the state of the socket:
484:
485:
486: my $State = $Socket->GetState();
487:
488:
489: SocketDump(6,$Socket);
490:
491: if ($State eq "Connected") {
492: # "init" is being sent...
493:
494: if ($Socket->Writable() != 0) {
495: # The write resulted in an error.
496: }
497:
498: } elsif ($State eq "Initialized") {
499:
500: # Now that init was sent, we switch
501: # to watching for readability:
502:
503: $Watcher->poll("r");
504: $Watcher->cb(\&LondReadable);
505:
506: } elsif ($State eq "ChallengeReceived") {
507: # We received the challenge, now we
508: # are echoing it back. This is a no-op,
509: # we're waiting for the state to change
510:
511: if($Socket->Writable() != 0) {
512: # Write of the next chunk resulted in an error.
513: }
514:
515: } elsif ($State eq "ChallengeReplied") {
516: # The echo was sent back, so we switch
517: # to watching readability.
518:
519: $Watcher->poll("r");
520: $Watcher->cb(\&LondReadable);
521:
522: } elsif ($State eq "RequestingKey") {
523: # At this time we're requesting the key.
524: # again, this is essentially a no-op.
525: # we'll write the next chunk until the
526: # state changes.
527:
528: if($Socket->Writable() != 0) {
529: # Write resulted in an error.
530: }
531:
532: } elsif ($State eq "ReceivingKey") {
533: # Now we need to wait for the key
534: # to come back from the peer:
535:
536: $Watcher->poll("r");
537: $Watcher->cb(\&LondReadable);
538:
539: } elsif ($State eq "SendingRequest") {
540: # At this time we are sending a request to the
541: # peer... write the next chunk:
542:
543: if($Socket->Writable() != 0) {
544: # Write resulted in an error.
545:
546: }
547:
548: } elsif ($State eq "ReceivingReply") {
549: # The send has completed. Wait for the
550: # data to come in for a reply.
551: Debug(8,"Writable sent request/receiving reply");
552: $Watcher->poll("r");
553: $Watcher->cb(\&LondReadable);
554:
555: } else {
556: # Control only passes here on an error:
557: # the socket state does not match any
558: # of the known states... so an error
559: # must be logged.
560:
561: &Debug(4, "Invalid socket state ".$State."\n");
562: }
563:
564: }
565:
566: =pod
567: =head2 MakeLondConnection
568: Create a new lond connection object, and start it towards
569: its initial idleness. Once idle, it becomes elligible to
570: receive transactions from the work queue. If the work queue
571: is not empty when the connection is completed and becomes idle,
572: it will dequeue an entry and start off on it.
573: =cut
574: sub MakeLondConnection {
575: Debug(4,"MakeLondConnection to ".GetServerHost()." on port "
576: .GetServerPort());
577:
578: my $Connection = LondConnection->new(&GetServerHost(),
579: &GetServerPort());
580:
581: if($Connection == undef) { # Needs to be more robust later.
582: die "Failed to make a connection!!".$!."\n";
583:
584: }
585: # The connection needs to have writability
586: # monitored in order to send the init sequence
587: # that starts the whole authentication/key
588: # exchange underway.
589: #
590: my $Socket = $Connection->GetSocket();
591: if($Socket == undef) {
592: die "did not get a socket from the connection";
593: } else {
594: &Debug(9,"MakeLondConnection got socket: ".$Socket);
595: }
596:
597:
598: $event = Event->io(fd => $Socket,
599: poll => 'w',
600: cb => \&LondWritable,
601: data => ($Connection, undef),
602: desc => 'Connection to lond server');
603: $ActiveConnections{$Lond} = $event;
604:
605: $ConnectionCount++;
606:
607:
608: }
609: =pod
610: =head2 StartRequest
611: Starts a lond request going on a specified lond connection.
612: parameters are:
613: =item $Lond - Connection to the lond that will send the transaction
614: and receive the reply.
615: =item $Client - Connection to the client that is making this request
616: We got the request from this socket, and when the request has
617: been relayed to lond and we get a reply back from lond it will
618: get sent to this socket.
619: =item $Request - The text of the request to send.
620: =cut
621:
622: sub StartRequest {
623: my $Lond = shift;
624: my $Client = shift;
625: my $Request = shift;
626:
627: Debug(6, "StartRequest: ".$Request);
628:
629: my $Socket = $Lond->GetSocket();
630:
631: $ActiveTransactions{$Lond} = $Client; # Socket to relay to client.
632:
633: $Lond->InitiateTransaction($Request);
634: $event = Event->io(fd => $Lond->GetSocket(),
635: poll => "w",
636: cb => \&LondWritable,
637: data => $Lond,
638: desc => "lond transaction connection");
639: $ActiveConnections{$Lond} = $event;
640: Debug(8," Start Request made watcher data with ".$event->data."\n");
641: }
642:
643: =pod
644: =head2 QueueTransaction
645: - If there is an idle lond connection, it is put to
646: work doing this transaction. Otherwise, the transaction is
647: placed in the work queue. If placed in the work queue and the
648: maximum number of connections has not yet been created, a new
649: connection will be started. Our goal is to eventually have
650: a sufficient number of connections that the work queue will
651: typically be empty.
652: parameters are:
653: =item Socket open on the lonc client.
654: =item Request data to send to the lond.
655:
656: =cut
657: sub QueueTransaction {
658: my $requestSocket = shift;
659: my $requestData = shift;
660:
661: Debug(6,"QueueTransaction: ".$requestData);
662:
663: my $LondSocket = $IdleConnections->pop();
664: if(!defined $LondSocket) { # Need to queue request.
665: Debug(8,"Must queue...");
666: $ClientQueue->enqueue($requestSocket);
667: $WorkQueue->enqueue($requestData);
668: if($ConnectionCount < $MaxConnectionCount) {
669: Debug(4,"Starting additional lond connection");
670: MakeLondConnection();
671: }
672: } else { # Can start the request:
673: Debug(8,"Can start...");
674: StartRequest($LondSocket, $requestSocket, $requestData);
675: }
676: }
677:
678: #-------------------------- Lonc UNIX socket handling ---------------------
679: =pod
680: =head2 ClientRequest
681: Callback that is called when data can be read from the
682: UNIX domain socket connecting us with an apache server process.
683:
684: =cut
685:
686: sub ClientRequest {
687: Debug(6, "ClientRequest");
688: my $event = shift;
689: my $watcher = $event->w;
690: my $socket = $watcher->fd;
691: my $data = $watcher->data;
692: my $thisread;
693:
694: Debug(9, " Watcher named: ".$watcher->desc);
695:
696: my $rv = $socket->recv($thisread, POSIX::BUFSIZ, 0);
697: Debug(8, "rcv: data length = ".length($thisread)
698: ." read =".$thisread);
699: unless (defined $rv && length($thisread)) {
700: # Likely eof on socket.
701: Debug(5,"Client Socket closed on lonc for ".$RemoteHost);
702: close($socket);
703: $watcher->cancel();
704: delete($ActiveClients{$socket});
705: }
706: Debug(8,"Data: ".$data." this read: ".$thisread);
707: $data = $data.$thisread; # Append new data.
708: $watcher->data($data);
709: if($data =~ /(.*\n)/) { # Request entirely read.
710: Debug(8, "Complete transaction received: ".$data);
711: QueueTransaction($socket, $data);
712: $watcher->cancel(); # Done looking for input data.
713: }
714:
715: }
716:
717:
718: =pod
719: =head2 NewClient
720: Callback that is called when a connection is received on the
721: unix socket for a new client of lonc. The callback is parameterized
722: by the event.. which is a-priori assumed to be an io event, and therefore
723: has an fd member that is the Listener socket. We Accept the connection
724: and register a new event on the readability of that socket:
725: =cut
726: sub NewClient {
727: Debug(6, "NewClient");
728: my $event = shift; # Get the event parameters.
729: my $watcher = $event->w;
730: my $socket = $watcher->fd; # Get the event' socket.
731: my $connection = $socket->accept(); # Accept the client connection.
732: Debug(8,"Connection request accepted from "
733: .GetPeername($connection, AF_UNIX));
734:
735:
736: my $description = sprintf("Connection to lonc client %d",
737: $ClientConnection);
738: Debug(9, "Creating event named: ".$description);
739: Event->io(cb => \&ClientRequest,
740: poll => 'r',
741: desc => $description,
742: data => "",
743: fd => $connection);
744: $ActiveClients{$connection} = $ClientConnection;
745: $ClientConnection++;
746: }
747: =pod GetLoncSocketPath
748: Returns the name of the UNIX socket on which to listen for client
749: connections.
750:
751: =cut
752: sub GetLoncSocketPath {
753: return $UnixSocketDir."/".GetServerHost();
754: }
755:
756: =pod GetServerHost
757: Returns the host whose lond we talk with.
758: =cut
759: sub GetServerHost { # Stub - get this from config.
760: return $RemoteHost; # Setup by the fork.
761: }
762: =pod GetServerPort
763: Returns the lond port number.
764: =cut
765: sub GetServerPort { # Stub - get this from config.
766: return $perlvar{londPort};
767: }
768: =pod SetupLoncListener
769: Setup a lonc listener event. The event is called when
770: the socket becomes readable.. that corresponds to the
771: receipt of a new connection. The event handler established
772: will accept the connection (creating a communcations channel), that
773: int turn will establish another event handler to subess requests.
774:
775: =cut
776: sub SetupLoncListener {
777:
778: my $socket;
779: my $SocketName = GetLoncSocketPath();
780: unlink($SocketName);
781: unless ($socket = IO::Socket::UNIX->new(Local => $SocketName,
782: Listen => 10,
783: Type => SOCK_STREAM)) {
784: die "Failed to create a lonc listner socket";
785: }
786: Event->io(cb => \&NewClient,
787: poll => 'r',
788: desc => 'Lonc listener Unix Socket',
789: fd => $socket);
790: }
791:
792: =pod
793: =head2 ChildProcess
794:
795: This sub implements a child process for a single lonc daemon.
796:
797: =cut
798:
799: sub ChildProcess {
800:
801: print "Loncnew\n";
802:
803: # For now turn off signals.
804:
805: $SIG{QUIT} = IGNORE;
806: $SIG{HUP} = IGNORE;
807: $SIG{USR1} = IGNORE;
808: $SIG{INT} = IGNORE;
809: $SIG{CHLD} = IGNORE;
810: $SIG{__DIE__} = IGNORE;
811:
812: SetupTimer();
813:
814: SetupLoncListener();
815:
816: $Event::Debuglevel = $DebugLevel;
817:
818: Debug(9, "Making initial lond connection for ".$RemoteHost);
819:
820: # Setup the initial server connection:
821:
822: &MakeLondConnection();
823:
824: Debug(9,"Entering event loop");
825: my $ret = Event::loop(); # Start the main event loop.
826:
827:
828: die "Main event loop exited!!!";
829: }
830:
831: # Create a new child for host passed in:
832:
833: sub CreateChild {
834: my $host = shift;
835: $RemoteHost = $host;
836: Debug(3, "Forking off child for ".$RemoteHost);
837: sleep(5);
838: $pid = fork;
839: if($pid) { # Parent
840: $ChildHash{$pid} = $RemoteHost;
841: } else { # child.
842: ChildProcess;
843: }
844:
845: }
846: #
847: # Parent process logic pass 1:
848: # For each entry in the hosts table, we will
849: # fork off an instance of ChildProcess to service the transactions
850: # to that host. Each pid will be entered in a global hash
851: # with the value of the key, the host.
852: # The parent will then enter a loop to wait for process exits.
853: # Each exit gets logged and the child gets restarted.
854: #
855:
856: my $HostIterator = LondConnection::GetHostIterator;
857: while (! $HostIterator->end()) {
858:
859: $hostentryref = $HostIterator->get();
860: CreateChild($hostentryref->[0]);
861: $HostIterator->next();
862: }
863:
864: # Maintain the population:
865:
866: while(1) {
867: $deadchild = wait();
868: if(exists $ChildHash{$deadchild}) { # need to restart.
869: $deadhost = $ChildHash{$deadchild};
870: delete($ChildHash{$deadchild});
871: Debug(4,"Lost child pid= ".$deadchild.
872: "Connected to host ".$deadhost);
873: CreateChild($deadhost);
874: }
875: }
876:
877: =head1 Theory
878: The event class is used to build this as a single process with
879: an event driven model. The following events are handled:
880:
881: =item UNIX Socket connection Received
882:
883: =item Request data arrives on UNIX data transfer socket.
884:
885: =item lond connection becomes writable.
886:
887: =item timer fires at 1 second intervals.
888:
889: All sockets are run in non-blocking mode. Timeouts managed by the timer
890: handler prevents hung connections.
891:
892: Key data structures:
893: =item RequestQueue - A queue of requests received from UNIX sockets that are
894: waiting for a chance to be forwarded on a lond connection socket.
895:
896: =item ActiveConnections - A hash of lond connections that have transactions
897: in process that are available to be timed out.
898:
899: =item ActiveTransactions - A hash indexed by lond connections that
900: contain the client reply socket for each connection that has an active
901: transaction on it.
902:
903: =item IdleConnections - A hash of lond connections that have no work
904: to do. These connections can be closed if they are idle for a long
905: enough time.
906: =cut
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