1: #!/usr/bin/perl
2: # The LearningOnline Network with CAPA
3: # lonc maintains the connections to remote computers
4: #
5: # $Id: loncnew,v 1.3 2003/04/18 03:10:36 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:
107: =pod
108:
109: =head2 GetPeerName
110:
111: Returns the name of the host that a socket object is connected to.
112:
113: =cut
114:
115: sub GetPeername {
116: my $connection = shift;
117: my $AdrFamily = shift;
118: my $peer = $connection->peername();
119: my $peerport;
120: my $peerip;
121: if($AdrFamily == AF_INET) {
122: ($peerport, $peerip) = sockaddr_in($peer);
123: my $peername = gethostbyaddr($iaddr, $AdrFamily);
124: return $peername;
125: } elsif ($AdrFamily == AF_UNIX) {
126: my $peerfile;
127: ($peerfile) = sockaddr_un($peer);
128: return $peerfile;
129: }
130: }
131: #----------------------------- Timer management ------------------------
132: =pod
133:
134: =head2 Debug
135:
136: Invoked to issue a debug message.
137:
138: =cut
139:
140: sub Debug {
141: my $level = shift;
142: my $message = shift;
143: if ($level <= $DebugLevel) {
144: print $message." host = ".$RemoteHost."\n";
145: }
146: }
147:
148: sub SocketDump {
149: my $level = shift;
150: my $socket= shift;
151: if($level <= $DebugLevel) {
152: $socket->Dump();
153: }
154: }
155:
156: =pod
157:
158: =head2 Tick
159:
160: Invoked each timer tick.
161:
162: =cut
163:
164: sub Tick {
165: my $client;
166: Debug(6, "Tick");
167: Debug(6, " Current connection count: ".$ConnectionCount);
168: foreach $client (keys %ActiveClients) {
169: Debug(7, " Have client: with id: ".$ActiveClients{$client});
170: }
171: }
172:
173: =pod
174:
175: =head2 SetupTimer
176:
177: Sets up a 1 per sec recurring timer event. The event handler is used to:
178:
179: =item
180:
181: Trigger timeouts on communications along active sockets.
182:
183: =item
184:
185: Trigger disconnections of idle sockets.
186:
187: =cut
188:
189: sub SetupTimer {
190: Debug(6, "SetupTimer");
191: Event->timer(interval => 1, debug => 1, cb => \&Tick );
192: }
193:
194: =pod
195:
196: =head2 ServerToIdle
197:
198: This function is called when a connection to the server is
199: ready for more work.
200:
201: If there is work in the Work queue the top element is dequeued
202: and the connection will start to work on it. If the work queue is
203: empty, the connection is pushed on the idle connection stack where
204: it will either get another work unit, or alternatively, if it sits there
205: long enough, it will be shut down and released.
206:
207: =cut
208:
209: sub ServerToIdle {
210: my $Socket = shift; # Get the socket.
211:
212: &Debug(6, "Server to idle");
213:
214: # If there's work to do, start the transaction:
215:
216: $reqdata = $WorkQueue->dequeue();
217: Debug(9, "Queue gave request data: ".$reqdata);
218: unless($reqdata eq undef) {
219: my $unixSocket = $ClientQueue->dequeue();
220: &Debug(6, "Starting new work request");
221: &Debug(7, "Request: ".$reqdata);
222:
223: &StartRequest($Socket, $unixSocket, $reqdata);
224: } else {
225:
226: # There's no work waiting, so push the server to idle list.
227: &Debug(8, "No new work requests, server connection going idle");
228: delete($ActiveTransactions{$Socket});
229: $IdleConnections->push($Socket);
230: }
231: }
232:
233: =pod
234:
235: =head2 ClientWritable
236:
237: Event callback for when a client socket is writable.
238:
239: This callback is established when a transaction reponse is
240: avaiable from lond. The response is forwarded to the unix socket
241: as it becomes writable in this sub.
242:
243: Parameters:
244:
245: =item Event
246:
247: The event that has been triggered. Event->w->data is
248: the data and Event->w->fd is the socket to write.
249:
250: =cut
251:
252: sub ClientWritable {
253: my $Event = shift;
254: my $Watcher = $Event->w;
255: my $Data = $Watcher->data;
256: my $Socket = $Watcher->fd;
257:
258: # Try to send the data:
259:
260: &Debug(6, "ClientWritable writing".$Data);
261: &Debug(9, "Socket is: ".$Socket);
262:
263: my $result = $Socket->send($Data, 0);
264:
265: # $result undefined: the write failed.
266: # otherwise $result is the number of bytes written.
267: # Remove that preceding string from the data.
268: # If the resulting data is empty, destroy the watcher
269: # and set up a read event handler to accept the next
270: # request.
271:
272: &Debug(9,"Send result is ".$result." Defined: ".defined($result));
273: if(defined($result)) {
274: &Debug(9, "send result was defined");
275: if($result == length($Data)) { # Entire string sent.
276: &Debug(9, "ClientWritable data all written");
277: $Watcher->cancel();
278: #
279: # Set up to read next request from socket:
280:
281: my $descr = sprintf("Connection to lonc client %d",
282: $ActiveClients{$Socket});
283: Event->io(cb => \&ClientRequest,
284: poll => 'r',
285: desc => $descr,
286: data => "",
287: fd => $Socket);
288:
289: } else { # Partial string sent.
290: $Watcher->data(substr($Data, $result));
291: }
292:
293: } else { # Error of some sort...
294:
295: # Some errnos are possible:
296: my $errno = $!;
297: if($errno == POSIX::EWOULDBLOCK ||
298: $errno == POSIX::EAGAIN ||
299: $errno == POSIX::EINTR) {
300: # No action taken?
301: } else { # Unanticipated errno.
302: &Debug(5,"ClientWritable error or peer shutdown".$RemoteHost);
303: $Watcher->cancel; # Stop the watcher.
304: $Socket->shutdown(2); # Kill connection
305: $Socket->close(); # Close the socket.
306: }
307:
308: }
309: }
310:
311: =pod
312:
313: =head2 CompleteTransaction
314:
315: Called when the reply data has been received for a lond
316: transaction. The reply data must now be sent to the
317: ultimate client on the other end of the Unix socket. This is
318: done by setting up a writable event for the socket with the
319: data the reply data.
320:
321: Parameters:
322:
323: =item Socket
324:
325: Socket on which the lond transaction occured. This is a
326: LondConnection. The data received is in the TransactionReply member.
327:
328: =item Client
329:
330: Unix domain socket open on the ultimate client.
331:
332: =cut
333:
334: sub CompleteTransaction {
335: &Debug(6,"Complete transaction");
336: my $Socket = shift;
337: my $Client = shift;
338:
339: my $data = $Socket->GetReply(); # Data to send.
340:
341: &Debug(8," Reply was: ".$data);
342: my $Serial = $ActiveClients{$Client};
343: my $desc = sprintf("Connection to lonc client %d",
344: $Serial);
345: Event->io(fd => $Client,
346: poll => "w",
347: desc => $desc,
348: cb => \&ClientWritable,
349: data => $data);
350: }
351:
352:
353: =pod
354:
355: =head2 LondReadable
356:
357: This function is called whenever a lond connection
358: is readable. The action is state dependent:
359:
360: =head3 State=Initialized
361:
362: We''re waiting for the challenge, this is a no-op until the
363: state changes.
364:
365: =head3 State=Challenged
366:
367: The challenge has arrived we need to transition to Writable.
368: The connection must echo the challenge back.
369:
370: =head3 State=ChallengeReplied
371:
372: The challenge has been replied to. The we are receiveing the
373: 'ok' from the partner.
374:
375: =head3 State=RequestingKey
376:
377: The ok has been received and we need to send the request for
378: an encryption key. Transition to writable for that.
379:
380: =head3 State=ReceivingKey
381:
382: The the key has been requested, now we are reading the new key.
383:
384: =head3 State=Idle
385:
386: The encryption key has been negotiated or we have finished
387: reading data from the a transaction. If the callback data has
388: a client as well as the socket iformation, then we are
389: doing a transaction and the data received is relayed to the client
390: before the socket is put on the idle list.
391:
392: =head3 State=SendingRequest
393:
394: I do not think this state can be received here, but if it is,
395: the appropriate thing to do is to transition to writable, and send
396: the request.
397:
398: =head3 State=ReceivingReply
399:
400: We finished sending the request to the server and now transition
401: to readable to receive the reply.
402:
403: The parameter to this function are:
404:
405: The event. Implicit in this is the watcher and its data. The data
406: contains at least the lond connection object and, if a
407: transaction is in progress, the socket attached to the local client.
408:
409: =cut
410:
411: sub LondReadable {
412: my $Event = shift;
413: my $Watcher = $Event->w;
414: my $Socket = $Watcher->data;
415: my $client = undef;
416:
417:
418: my $State = $Socket->GetState(); # All action depends on the state.
419:
420: &Debug(6,"LondReadable called state = ".$State);
421: SocketDump(6, $Socket);
422:
423: if($Socket->Readable() != 0) {
424: # bad return from socket read.
425: }
426: SocketDump(6,$Socket);
427:
428: $State = $Socket->GetState(); # Update in case of transition.
429: &Debug(6, "After read, state is ".$State);
430:
431: if($State eq "Initialized") {
432:
433:
434: } elsif ($State eq "ChallengeReceived") {
435: # The challenge must be echoed back; The state machine
436: # in the connection takes care of setting that up. Just
437: # need to transition to writable:
438:
439: $Watcher->poll("w");
440: $Watcher->cb(\&LondWritable);
441:
442: } elsif ($State eq "ChallengeReplied") {
443:
444:
445: } elsif ($State eq "RequestingKey") {
446: # The ok was received. Now we need to request the key
447: # That requires us to be writable:
448:
449: $Watcher->poll("w");
450: $Watcher->cb(\&LondWritable);
451:
452: } elsif ($State eq "ReceivingKey") {
453:
454: } elsif ($State eq "Idle") {
455: # If necessary, complete a transaction and then go into the
456: # idle queue.
457: if(exists($ActiveTransactions{$Socket})) {
458: Debug(8,"Completing transaction!!");
459: CompleteTransaction($Socket,
460: $ActiveTransactions{$Socket});
461: }
462: $Watcher->cancel();
463: ServerToIdle($Socket); # Next work unit or idle.
464:
465: } elsif ($State eq "SendingRequest") {
466: # We need to be writable for this and probably don't belong
467: # here inthe first place.
468:
469: Deubg(6, "SendingRequest state encountered in readable");
470: $Watcher->poll("w");
471: $Watcher->cb(\&LondWritable);
472:
473: } elsif ($State eq "ReceivingReply") {
474:
475:
476: } else {
477: # Invalid state.
478: Debug(4, "Invalid state in LondReadable");
479: }
480: }
481:
482: =pod
483:
484: =head2 LondWritable
485:
486: This function is called whenever a lond connection
487: becomes writable while there is a writeable monitoring
488: event. The action taken is very state dependent:
489:
490: =head3 State = Connected
491:
492: The connection is in the process of sending the 'init' hailing to the
493: lond on the remote end. The connection object''s Writable member is
494: called. On error, ConnectionError is called to destroy the connection
495: and remove it from the ActiveConnections hash
496:
497: =head3 Initialized
498:
499: 'init' has been sent, writability monitoring is removed and
500: readability monitoring is started with LondReadable as the callback.
501:
502: =head3 ChallengeReceived
503:
504: The connection has received the who are you challenge from the remote
505: system, and is in the process of sending the challenge
506: response. Writable is called.
507:
508: =head3 ChallengeReplied
509:
510: The connection has replied to the initial challenge The we switch to
511: monitoring readability looking for the server to reply with 'ok'.
512:
513: =head3 RequestingKey
514:
515: The connection is in the process of requesting its encryption key.
516: Writable is called.
517:
518: =head3 ReceivingKey
519:
520: The connection has sent the request for a key. Switch to readability
521: monitoring to accept the key
522:
523: =head3 SendingRequest
524:
525: The connection is in the process of sending a request to the server.
526: This request is part of a client transaction. All the states until
527: now represent the client setup protocol. Writable is called.
528:
529: =head3 ReceivingReply
530:
531: The connection has sent a request. Now it must receive a reply.
532: Readability monitoring is requested.
533:
534: This function is an event handler and therefore receives as
535: a parameter the event that has fired. The data for the watcher
536: of this event is a reference to a list of one or two elements,
537: depending on state. The first (and possibly only) element is the
538: socket. The second (present only if a request is in progress)
539: is the socket on which to return a reply to the caller.
540:
541: =cut
542:
543: sub LondWritable {
544: my $Event = shift;
545: my $Watcher = $Event->w;
546: my @data = $Watcher->data;
547: Debug(6,"LondWritable State = ".$State." data has ".@data." elts.\n");
548:
549: my $Socket = $data[0]; # I know there's at least a socket.
550:
551: # Figure out what to do depending on the state of the socket:
552:
553:
554: my $State = $Socket->GetState();
555:
556:
557: SocketDump(6,$Socket);
558:
559: if ($State eq "Connected") {
560: # "init" is being sent...
561:
562: if ($Socket->Writable() != 0) {
563: # The write resulted in an error.
564: }
565:
566: } elsif ($State eq "Initialized") {
567:
568: # Now that init was sent, we switch
569: # to watching for readability:
570:
571: $Watcher->poll("r");
572: $Watcher->cb(\&LondReadable);
573:
574: } elsif ($State eq "ChallengeReceived") {
575: # We received the challenge, now we
576: # are echoing it back. This is a no-op,
577: # we're waiting for the state to change
578:
579: if($Socket->Writable() != 0) {
580: # Write of the next chunk resulted in an error.
581: }
582:
583: } elsif ($State eq "ChallengeReplied") {
584: # The echo was sent back, so we switch
585: # to watching readability.
586:
587: $Watcher->poll("r");
588: $Watcher->cb(\&LondReadable);
589:
590: } elsif ($State eq "RequestingKey") {
591: # At this time we're requesting the key.
592: # again, this is essentially a no-op.
593: # we'll write the next chunk until the
594: # state changes.
595:
596: if($Socket->Writable() != 0) {
597: # Write resulted in an error.
598: }
599:
600: } elsif ($State eq "ReceivingKey") {
601: # Now we need to wait for the key
602: # to come back from the peer:
603:
604: $Watcher->poll("r");
605: $Watcher->cb(\&LondReadable);
606:
607: } elsif ($State eq "SendingRequest") {
608: # At this time we are sending a request to the
609: # peer... write the next chunk:
610:
611: if($Socket->Writable() != 0) {
612: # Write resulted in an error.
613:
614: }
615:
616: } elsif ($State eq "ReceivingReply") {
617: # The send has completed. Wait for the
618: # data to come in for a reply.
619: Debug(8,"Writable sent request/receiving reply");
620: $Watcher->poll("r");
621: $Watcher->cb(\&LondReadable);
622:
623: } else {
624: # Control only passes here on an error:
625: # the socket state does not match any
626: # of the known states... so an error
627: # must be logged.
628:
629: &Debug(4, "Invalid socket state ".$State."\n");
630: }
631:
632: }
633:
634: =pod
635:
636: =head2 MakeLondConnection
637:
638: Create a new lond connection object, and start it towards its initial
639: idleness. Once idle, it becomes elligible to receive transactions
640: from the work queue. If the work queue is not empty when the
641: connection is completed and becomes idle, it will dequeue an entry and
642: start off on it.
643:
644: =cut
645:
646: sub MakeLondConnection {
647: Debug(4,"MakeLondConnection to ".GetServerHost()." on port "
648: .GetServerPort());
649:
650: my $Connection = LondConnection->new(&GetServerHost(),
651: &GetServerPort());
652:
653: if($Connection == undef) { # Needs to be more robust later.
654: die "Failed to make a connection!!".$!."\n";
655:
656: }
657: # The connection needs to have writability
658: # monitored in order to send the init sequence
659: # that starts the whole authentication/key
660: # exchange underway.
661: #
662: my $Socket = $Connection->GetSocket();
663: if($Socket == undef) {
664: die "did not get a socket from the connection";
665: } else {
666: &Debug(9,"MakeLondConnection got socket: ".$Socket);
667: }
668:
669:
670: $event = Event->io(fd => $Socket,
671: poll => 'w',
672: cb => \&LondWritable,
673: data => ($Connection, undef),
674: desc => 'Connection to lond server');
675: $ActiveConnections{$Lond} = $event;
676:
677: $ConnectionCount++;
678:
679:
680: }
681:
682: =pod
683:
684: =head2 StartRequest
685:
686: Starts a lond request going on a specified lond connection.
687: parameters are:
688:
689: =item $Lond
690:
691: Connection to the lond that will send the transaction and receive the
692: reply.
693:
694: =item $Client
695:
696: Connection to the client that is making this request We got the
697: request from this socket, and when the request has been relayed to
698: lond and we get a reply back from lond it will get sent to this
699: socket.
700:
701: =item $Request
702:
703: The text of the request to send.
704:
705: =cut
706:
707: sub StartRequest {
708: my $Lond = shift;
709: my $Client = shift;
710: my $Request = shift;
711:
712: Debug(6, "StartRequest: ".$Request);
713:
714: my $Socket = $Lond->GetSocket();
715:
716: $ActiveTransactions{$Lond} = $Client; # Socket to relay to client.
717:
718: $Lond->InitiateTransaction($Request);
719: $event = Event->io(fd => $Lond->GetSocket(),
720: poll => "w",
721: cb => \&LondWritable,
722: data => $Lond,
723: desc => "lond transaction connection");
724: $ActiveConnections{$Lond} = $event;
725: Debug(8," Start Request made watcher data with ".$event->data."\n");
726: }
727:
728: =pod
729:
730: =head2 QueueTransaction
731:
732: If there is an idle lond connection, it is put to work doing this
733: transaction. Otherwise, the transaction is placed in the work queue.
734: If placed in the work queue and the maximum number of connections has
735: not yet been created, a new connection will be started. Our goal is
736: to eventually have a sufficient number of connections that the work
737: queue will typically be empty. parameters are:
738:
739: =item Socket
740:
741: open on the lonc client.
742:
743: =item Request
744:
745: data to send to the lond.
746:
747: =cut
748:
749: sub QueueTransaction {
750: my $requestSocket = shift;
751: my $requestData = shift;
752:
753: Debug(6,"QueueTransaction: ".$requestData);
754:
755: my $LondSocket = $IdleConnections->pop();
756: if(!defined $LondSocket) { # Need to queue request.
757: Debug(8,"Must queue...");
758: $ClientQueue->enqueue($requestSocket);
759: $WorkQueue->enqueue($requestData);
760: if($ConnectionCount < $MaxConnectionCount) {
761: Debug(4,"Starting additional lond connection");
762: MakeLondConnection();
763: }
764: } else { # Can start the request:
765: Debug(8,"Can start...");
766: StartRequest($LondSocket, $requestSocket, $requestData);
767: }
768: }
769:
770: #-------------------------- Lonc UNIX socket handling ---------------------
771:
772: =pod
773:
774: =head2 ClientRequest
775:
776: Callback that is called when data can be read from the UNIX domain
777: socket connecting us with an apache server process.
778:
779: =cut
780:
781: sub ClientRequest {
782: Debug(6, "ClientRequest");
783: my $event = shift;
784: my $watcher = $event->w;
785: my $socket = $watcher->fd;
786: my $data = $watcher->data;
787: my $thisread;
788:
789: Debug(9, " Watcher named: ".$watcher->desc);
790:
791: my $rv = $socket->recv($thisread, POSIX::BUFSIZ, 0);
792: Debug(8, "rcv: data length = ".length($thisread)
793: ." read =".$thisread);
794: unless (defined $rv && length($thisread)) {
795: # Likely eof on socket.
796: Debug(5,"Client Socket closed on lonc for ".$RemoteHost);
797: close($socket);
798: $watcher->cancel();
799: delete($ActiveClients{$socket});
800: }
801: Debug(8,"Data: ".$data." this read: ".$thisread);
802: $data = $data.$thisread; # Append new data.
803: $watcher->data($data);
804: if($data =~ /(.*\n)/) { # Request entirely read.
805: Debug(8, "Complete transaction received: ".$data);
806: QueueTransaction($socket, $data);
807: $watcher->cancel(); # Done looking for input data.
808: }
809:
810: }
811:
812:
813: =pod
814:
815: =head2 NewClient
816:
817: Callback that is called when a connection is received on the unix
818: socket for a new client of lonc. The callback is parameterized by the
819: event.. which is a-priori assumed to be an io event, and therefore has
820: an fd member that is the Listener socket. We Accept the connection
821: and register a new event on the readability of that socket:
822:
823: =cut
824:
825: sub NewClient {
826: Debug(6, "NewClient");
827: my $event = shift; # Get the event parameters.
828: my $watcher = $event->w;
829: my $socket = $watcher->fd; # Get the event' socket.
830: my $connection = $socket->accept(); # Accept the client connection.
831: Debug(8,"Connection request accepted from "
832: .GetPeername($connection, AF_UNIX));
833:
834:
835: my $description = sprintf("Connection to lonc client %d",
836: $ClientConnection);
837: Debug(9, "Creating event named: ".$description);
838: Event->io(cb => \&ClientRequest,
839: poll => 'r',
840: desc => $description,
841: data => "",
842: fd => $connection);
843: $ActiveClients{$connection} = $ClientConnection;
844: $ClientConnection++;
845: }
846:
847: =pod
848:
849: =head2 GetLoncSocketPath
850:
851: Returns the name of the UNIX socket on which to listen for client
852: connections.
853:
854: =cut
855:
856: sub GetLoncSocketPath {
857: return $UnixSocketDir."/".GetServerHost();
858: }
859:
860: =pod
861:
862: =head2 GetServerHost
863:
864: Returns the host whose lond we talk with.
865:
866: =cut
867:
868: sub GetServerHost { # Stub - get this from config.
869: return $RemoteHost; # Setup by the fork.
870: }
871:
872: =pod
873:
874: =head2 GetServerPort
875:
876: Returns the lond port number.
877:
878: =cut
879:
880: sub GetServerPort { # Stub - get this from config.
881: return $perlvar{londPort};
882: }
883:
884: =pod
885:
886: =head2 SetupLoncListener
887:
888: Setup a lonc listener event. The event is called when the socket
889: becomes readable.. that corresponds to the receipt of a new
890: connection. The event handler established will accept the connection
891: (creating a communcations channel), that int turn will establish
892: another event handler to subess requests.
893:
894: =cut
895:
896: sub SetupLoncListener {
897:
898: my $socket;
899: my $SocketName = GetLoncSocketPath();
900: unlink($SocketName);
901: unless ($socket = IO::Socket::UNIX->new(Local => $SocketName,
902: Listen => 10,
903: Type => SOCK_STREAM)) {
904: die "Failed to create a lonc listner socket";
905: }
906: Event->io(cb => \&NewClient,
907: poll => 'r',
908: desc => 'Lonc listener Unix Socket',
909: fd => $socket);
910: }
911:
912: =pod
913:
914: =head2 ChildProcess
915:
916: This sub implements a child process for a single lonc daemon.
917:
918: =cut
919:
920: sub ChildProcess {
921:
922: print "Loncnew\n";
923:
924: # For now turn off signals.
925:
926: $SIG{QUIT} = IGNORE;
927: $SIG{HUP} = IGNORE;
928: $SIG{USR1} = IGNORE;
929: $SIG{INT} = IGNORE;
930: $SIG{CHLD} = IGNORE;
931: $SIG{__DIE__} = IGNORE;
932:
933: SetupTimer();
934:
935: SetupLoncListener();
936:
937: $Event::Debuglevel = $DebugLevel;
938:
939: Debug(9, "Making initial lond connection for ".$RemoteHost);
940:
941: # Setup the initial server connection:
942:
943: &MakeLondConnection();
944:
945: Debug(9,"Entering event loop");
946: my $ret = Event::loop(); # Start the main event loop.
947:
948:
949: die "Main event loop exited!!!";
950: }
951:
952: # Create a new child for host passed in:
953:
954: sub CreateChild {
955: my $host = shift;
956: $RemoteHost = $host;
957: Debug(3, "Forking off child for ".$RemoteHost);
958: sleep(5);
959: $pid = fork;
960: if($pid) { # Parent
961: $ChildHash{$pid} = $RemoteHost;
962: } else { # child.
963: ChildProcess;
964: }
965:
966: }
967: #
968: # Parent process logic pass 1:
969: # For each entry in the hosts table, we will
970: # fork off an instance of ChildProcess to service the transactions
971: # to that host. Each pid will be entered in a global hash
972: # with the value of the key, the host.
973: # The parent will then enter a loop to wait for process exits.
974: # Each exit gets logged and the child gets restarted.
975: #
976:
977: my $HostIterator = LondConnection::GetHostIterator;
978: while (! $HostIterator->end()) {
979:
980: $hostentryref = $HostIterator->get();
981: CreateChild($hostentryref->[0]);
982: $HostIterator->next();
983: }
984:
985: # Maintain the population:
986:
987: while(1) {
988: $deadchild = wait();
989: if(exists $ChildHash{$deadchild}) { # need to restart.
990: $deadhost = $ChildHash{$deadchild};
991: delete($ChildHash{$deadchild});
992: Debug(4,"Lost child pid= ".$deadchild.
993: "Connected to host ".$deadhost);
994: CreateChild($deadhost);
995: }
996: }
997:
998: =head1 Theory
999:
1000: The event class is used to build this as a single process with an
1001: event driven model. The following events are handled:
1002:
1003: =item UNIX Socket connection Received
1004:
1005: =item Request data arrives on UNIX data transfer socket.
1006:
1007: =item lond connection becomes writable.
1008:
1009: =item timer fires at 1 second intervals.
1010:
1011: All sockets are run in non-blocking mode. Timeouts managed by the timer
1012: handler prevents hung connections.
1013:
1014: Key data structures:
1015:
1016: =item RequestQueue
1017:
1018: A queue of requests received from UNIX sockets that are
1019: waiting for a chance to be forwarded on a lond connection socket.
1020:
1021: =item ActiveConnections
1022:
1023: A hash of lond connections that have transactions in process that are
1024: available to be timed out.
1025:
1026: =item ActiveTransactions
1027:
1028: A hash indexed by lond connections that contain the client reply
1029: socket for each connection that has an active transaction on it.
1030:
1031: =item IdleConnections
1032:
1033: A hash of lond connections that have no work to do. These connections
1034: can be closed if they are idle for a long enough time.
1035:
1036: =cut
FreeBSD-CVSweb <freebsd-cvsweb@FreeBSD.org>
![[BACK]](/icons/back.gif){kind=icon}
Return to loncnew CVS log ![[TXT]](/icons/text.gif){kind=icon}
![[DIR]](/icons/dir.gif){kind=icon}
Up to [LON-CAPA] / loncom