1: #!/usr/bin/perl
2: # The LearningOnline Network with CAPA
3: # lonc maintains the connections to remote computers
4: #
5: # $Id: loncnew,v 1.4 2003/04/24 10:56:55 foxr 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: my $IdleSeconds = 0; # Number of seconds idle.
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: $0 = 'lonc: '.GetServerHost()." Connection count: ".$ConnectionCount;
167: Debug(6, "Tick");
168: Debug(6, " Current connection count: ".$ConnectionCount);
169: foreach $client (keys %ActiveClients) {
170: Debug(7, " Have client: with id: ".$ActiveClients{$client});
171: }
172: # Is it time to prune connection count:
173:
174:
175: if($IdleConnections->Count() &&
176: ($WorkQueue->Count() == 0)) { # Idle connections and nothing to do?
177: $IdleSeconds++;
178: if($IdleSeconds > $IdleTimeout) { # Prune a connection...
179: $Socket = $IdleConnections->pop();
180: KillSocket($Socket, 0);
181: }
182: } else {
183: $IdleSeconds = 0; # Reset idle count if not idle.
184: }
185: }
186:
187: =pod
188:
189: =head2 SetupTimer
190:
191: Sets up a 1 per sec recurring timer event. The event handler is used to:
192:
193: =item
194:
195: Trigger timeouts on communications along active sockets.
196:
197: =item
198:
199: Trigger disconnections of idle sockets.
200:
201: =cut
202:
203: sub SetupTimer {
204: Debug(6, "SetupTimer");
205: Event->timer(interval => 1, debug => 1, cb => \&Tick );
206: }
207:
208: =pod
209:
210: =head2 ServerToIdle
211:
212: This function is called when a connection to the server is
213: ready for more work.
214:
215: If there is work in the Work queue the top element is dequeued
216: and the connection will start to work on it. If the work queue is
217: empty, the connection is pushed on the idle connection stack where
218: it will either get another work unit, or alternatively, if it sits there
219: long enough, it will be shut down and released.
220:
221: =cut
222:
223: sub ServerToIdle {
224: my $Socket = shift; # Get the socket.
225:
226: &Debug(6, "Server to idle");
227:
228: # If there's work to do, start the transaction:
229:
230: $reqdata = $WorkQueue->dequeue();
231: Debug(9, "Queue gave request data: ".$reqdata);
232: unless($reqdata eq undef) {
233: my $unixSocket = $ClientQueue->dequeue();
234: &Debug(6, "Starting new work request");
235: &Debug(7, "Request: ".$reqdata);
236:
237: &StartRequest($Socket, $unixSocket, $reqdata);
238: } else {
239:
240: # There's no work waiting, so push the server to idle list.
241: &Debug(8, "No new work requests, server connection going idle");
242: delete($ActiveTransactions{$Socket});
243: $IdleConnections->push($Socket);
244: }
245: }
246:
247: =pod
248:
249: =head2 ClientWritable
250:
251: Event callback for when a client socket is writable.
252:
253: This callback is established when a transaction reponse is
254: avaiable from lond. The response is forwarded to the unix socket
255: as it becomes writable in this sub.
256:
257: Parameters:
258:
259: =item Event
260:
261: The event that has been triggered. Event->w->data is
262: the data and Event->w->fd is the socket to write.
263:
264: =cut
265:
266: sub ClientWritable {
267: my $Event = shift;
268: my $Watcher = $Event->w;
269: my $Data = $Watcher->data;
270: my $Socket = $Watcher->fd;
271:
272: # Try to send the data:
273:
274: &Debug(6, "ClientWritable writing".$Data);
275: &Debug(9, "Socket is: ".$Socket);
276:
277: my $result = $Socket->send($Data, 0);
278:
279: # $result undefined: the write failed.
280: # otherwise $result is the number of bytes written.
281: # Remove that preceding string from the data.
282: # If the resulting data is empty, destroy the watcher
283: # and set up a read event handler to accept the next
284: # request.
285:
286: &Debug(9,"Send result is ".$result." Defined: ".defined($result));
287: if(defined($result)) {
288: &Debug(9, "send result was defined");
289: if($result == length($Data)) { # Entire string sent.
290: &Debug(9, "ClientWritable data all written");
291: $Watcher->cancel();
292: #
293: # Set up to read next request from socket:
294:
295: my $descr = sprintf("Connection to lonc client %d",
296: $ActiveClients{$Socket});
297: Event->io(cb => \&ClientRequest,
298: poll => 'r',
299: desc => $descr,
300: data => "",
301: fd => $Socket);
302:
303: } else { # Partial string sent.
304: $Watcher->data(substr($Data, $result));
305: }
306:
307: } else { # Error of some sort...
308:
309: # Some errnos are possible:
310: my $errno = $!;
311: if($errno == POSIX::EWOULDBLOCK ||
312: $errno == POSIX::EAGAIN ||
313: $errno == POSIX::EINTR) {
314: # No action taken?
315: } else { # Unanticipated errno.
316: &Debug(5,"ClientWritable error or peer shutdown".$RemoteHost);
317: $Watcher->cancel; # Stop the watcher.
318: $Socket->shutdown(2); # Kill connection
319: $Socket->close(); # Close the socket.
320: }
321:
322: }
323: }
324:
325: =pod
326:
327: =head2 CompleteTransaction
328:
329: Called when the reply data has been received for a lond
330: transaction. The reply data must now be sent to the
331: ultimate client on the other end of the Unix socket. This is
332: done by setting up a writable event for the socket with the
333: data the reply data.
334:
335: Parameters:
336:
337: =item Socket
338:
339: Socket on which the lond transaction occured. This is a
340: LondConnection. The data received is in the TransactionReply member.
341:
342: =item Client
343:
344: Unix domain socket open on the ultimate client.
345:
346: =cut
347:
348: sub CompleteTransaction {
349: &Debug(6,"Complete transaction");
350: my $Socket = shift;
351: my $Client = shift;
352:
353: my $data = $Socket->GetReply(); # Data to send.
354:
355: &Debug(8," Reply was: ".$data);
356: my $Serial = $ActiveClients{$Client};
357: my $desc = sprintf("Connection to lonc client %d",
358: $Serial);
359: Event->io(fd => $Client,
360: poll => "w",
361: desc => $desc,
362: cb => \&ClientWritable,
363: data => $data);
364: }
365: =pod
366: =head2 FailTransaction
367:
368: Finishes a transaction with failure because the associated lond socket
369: disconnected. It is up to our client to retry if desired.
370:
371: Parameters:
372:
373: =item client
374:
375: The UNIX domain socket open on our client.
376:
377: =cut
378:
379: sub FailTransaction {
380: my $client = shift;
381:
382: &Debug(8, "Failing transaction due to disconnect");
383: my $Serial = $ActiveClients{$client};
384: my $desc = sprintf("Connection to lonc client %d", $Serial);
385: my $data = "error: Connection to lond lost\n";
386:
387: Event->io(fd => $client,
388: poll => "w",
389: desc => $desc,
390: cb => \&ClientWritable,
391: data => $data);
392:
393: }
394:
395: =pod
396:
397: =head2 KillSocket
398:
399: Destroys a socket. This function can be called either when a socket
400: has died of 'natural' causes or because a socket needs to be pruned due to
401: idleness. If the socket has died naturally, if there are no longer any
402: live connections a new connection is created (in case there are transactions
403: in the queue). If the socket has been pruned, it is never re-created.
404:
405: Parameters:
406:
407: =item Socket
408:
409: The socket to kill off.
410:
411: =item Restart
412:
413: nonzero if we are allowed to create a new connection.
414:
415:
416: =cut
417: sub KillSocket {
418: my $Socket = shift;
419: my $Restart= shift;
420:
421: # If the socket came from the active connection set, delete it.
422: # otherwise it came from the idle set and has already been destroyed:
423:
424: if(exists($ActiveTransactions{$Socket})) {
425: delete ($ActiveTransactions{$Socket});
426: }
427: if(exists($ActiveConnections{$Socket})) {
428: delete($ActiveConnections{$Socket});
429: }
430: $ConnectionCount--;
431: if( ($ConnectionCount = 0) && ($Restart)) {
432: MakeLondConnection();
433: }
434:
435: }
436:
437: =pod
438:
439: =head2 LondReadable
440:
441: This function is called whenever a lond connection
442: is readable. The action is state dependent:
443:
444: =head3 State=Initialized
445:
446: We''re waiting for the challenge, this is a no-op until the
447: state changes.
448:
449: =head3 State=Challenged
450:
451: The challenge has arrived we need to transition to Writable.
452: The connection must echo the challenge back.
453:
454: =head3 State=ChallengeReplied
455:
456: The challenge has been replied to. The we are receiveing the
457: 'ok' from the partner.
458:
459: =head3 State=RequestingKey
460:
461: The ok has been received and we need to send the request for
462: an encryption key. Transition to writable for that.
463:
464: =head3 State=ReceivingKey
465:
466: The the key has been requested, now we are reading the new key.
467:
468: =head3 State=Idle
469:
470: The encryption key has been negotiated or we have finished
471: reading data from the a transaction. If the callback data has
472: a client as well as the socket iformation, then we are
473: doing a transaction and the data received is relayed to the client
474: before the socket is put on the idle list.
475:
476: =head3 State=SendingRequest
477:
478: I do not think this state can be received here, but if it is,
479: the appropriate thing to do is to transition to writable, and send
480: the request.
481:
482: =head3 State=ReceivingReply
483:
484: We finished sending the request to the server and now transition
485: to readable to receive the reply.
486:
487: The parameter to this function are:
488:
489: The event. Implicit in this is the watcher and its data. The data
490: contains at least the lond connection object and, if a
491: transaction is in progress, the socket attached to the local client.
492:
493: =cut
494:
495: sub LondReadable {
496: my $Event = shift;
497: my $Watcher = $Event->w;
498: my $Socket = $Watcher->data;
499: my $client = undef;
500:
501:
502: my $State = $Socket->GetState(); # All action depends on the state.
503:
504: &Debug(6,"LondReadable called state = ".$State);
505: SocketDump(6, $Socket);
506:
507: if($Socket->Readable() != 0) {
508: # bad return from socket read. Currently this means that
509: # The socket has become disconnected. We fail the transaction.
510:
511: if(exists($ActiveTransactions{$Socket})) {
512: Debug(3,"Lond connection lost failing transaction");
513: FailTransaction($ActiveTransactions{$Socket});
514: }
515: $Watcher->cancel();
516: KillSocket($Socket, 1);
517: return;
518: }
519: SocketDump(6,$Socket);
520:
521: $State = $Socket->GetState(); # Update in case of transition.
522: &Debug(6, "After read, state is ".$State);
523:
524: if($State eq "Initialized") {
525:
526:
527: } elsif ($State eq "ChallengeReceived") {
528: # The challenge must be echoed back; The state machine
529: # in the connection takes care of setting that up. Just
530: # need to transition to writable:
531:
532: $Watcher->poll("w");
533: $Watcher->cb(\&LondWritable);
534:
535: } elsif ($State eq "ChallengeReplied") {
536:
537:
538: } elsif ($State eq "RequestingKey") {
539: # The ok was received. Now we need to request the key
540: # That requires us to be writable:
541:
542: $Watcher->poll("w");
543: $Watcher->cb(\&LondWritable);
544:
545: } elsif ($State eq "ReceivingKey") {
546:
547: } elsif ($State eq "Idle") {
548: # If necessary, complete a transaction and then go into the
549: # idle queue.
550: if(exists($ActiveTransactions{$Socket})) {
551: Debug(8,"Completing transaction!!");
552: CompleteTransaction($Socket,
553: $ActiveTransactions{$Socket});
554: }
555: $Watcher->cancel();
556: ServerToIdle($Socket); # Next work unit or idle.
557:
558: } elsif ($State eq "SendingRequest") {
559: # We need to be writable for this and probably don't belong
560: # here inthe first place.
561:
562: Deubg(6, "SendingRequest state encountered in readable");
563: $Watcher->poll("w");
564: $Watcher->cb(\&LondWritable);
565:
566: } elsif ($State eq "ReceivingReply") {
567:
568:
569: } else {
570: # Invalid state.
571: Debug(4, "Invalid state in LondReadable");
572: }
573: }
574:
575: =pod
576:
577: =head2 LondWritable
578:
579: This function is called whenever a lond connection
580: becomes writable while there is a writeable monitoring
581: event. The action taken is very state dependent:
582:
583: =head3 State = Connected
584:
585: The connection is in the process of sending the 'init' hailing to the
586: lond on the remote end. The connection object''s Writable member is
587: called. On error, ConnectionError is called to destroy the connection
588: and remove it from the ActiveConnections hash
589:
590: =head3 Initialized
591:
592: 'init' has been sent, writability monitoring is removed and
593: readability monitoring is started with LondReadable as the callback.
594:
595: =head3 ChallengeReceived
596:
597: The connection has received the who are you challenge from the remote
598: system, and is in the process of sending the challenge
599: response. Writable is called.
600:
601: =head3 ChallengeReplied
602:
603: The connection has replied to the initial challenge The we switch to
604: monitoring readability looking for the server to reply with 'ok'.
605:
606: =head3 RequestingKey
607:
608: The connection is in the process of requesting its encryption key.
609: Writable is called.
610:
611: =head3 ReceivingKey
612:
613: The connection has sent the request for a key. Switch to readability
614: monitoring to accept the key
615:
616: =head3 SendingRequest
617:
618: The connection is in the process of sending a request to the server.
619: This request is part of a client transaction. All the states until
620: now represent the client setup protocol. Writable is called.
621:
622: =head3 ReceivingReply
623:
624: The connection has sent a request. Now it must receive a reply.
625: Readability monitoring is requested.
626:
627: This function is an event handler and therefore receives as
628: a parameter the event that has fired. The data for the watcher
629: of this event is a reference to a list of one or two elements,
630: depending on state. The first (and possibly only) element is the
631: socket. The second (present only if a request is in progress)
632: is the socket on which to return a reply to the caller.
633:
634: =cut
635:
636: sub LondWritable {
637: my $Event = shift;
638: my $Watcher = $Event->w;
639: my @data = $Watcher->data;
640: Debug(6,"LondWritable State = ".$State." data has ".@data." elts.\n");
641:
642: my $Socket = $data[0]; # I know there's at least a socket.
643:
644: # Figure out what to do depending on the state of the socket:
645:
646:
647: my $State = $Socket->GetState();
648:
649:
650: SocketDump(6,$Socket);
651:
652: if ($State eq "Connected") {
653:
654: if ($Socket->Writable() != 0) {
655: # The write resulted in an error.
656: # We'll treat this as if the socket got disconnected:
657: if(exists($ActiveTransactions{$Socket})) {
658: Debug(3, "Lond connection lost, failing transactions");
659: FailTransaction($ActiveTransactions{$Socket});
660: }
661: $Watcher->cancel();
662: KillSocket($Socket, 1);
663: return;
664: }
665: # "init" is being sent...
666:
667:
668: } elsif ($State eq "Initialized") {
669:
670: # Now that init was sent, we switch
671: # to watching for readability:
672:
673: $Watcher->poll("r");
674: $Watcher->cb(\&LondReadable);
675:
676: } elsif ($State eq "ChallengeReceived") {
677: # We received the challenge, now we
678: # are echoing it back. This is a no-op,
679: # we're waiting for the state to change
680:
681: if($Socket->Writable() != 0) {
682: # Write of the next chunk resulted in an error.
683: }
684:
685: } elsif ($State eq "ChallengeReplied") {
686: # The echo was sent back, so we switch
687: # to watching readability.
688:
689: $Watcher->poll("r");
690: $Watcher->cb(\&LondReadable);
691:
692: } elsif ($State eq "RequestingKey") {
693: # At this time we're requesting the key.
694: # again, this is essentially a no-op.
695: # we'll write the next chunk until the
696: # state changes.
697:
698: if($Socket->Writable() != 0) {
699: # Write resulted in an error.
700: }
701:
702: } elsif ($State eq "ReceivingKey") {
703: # Now we need to wait for the key
704: # to come back from the peer:
705:
706: $Watcher->poll("r");
707: $Watcher->cb(\&LondReadable);
708:
709: } elsif ($State eq "SendingRequest") {
710: # At this time we are sending a request to the
711: # peer... write the next chunk:
712:
713: if($Socket->Writable() != 0) {
714: # Write resulted in an error.
715:
716: }
717:
718: } elsif ($State eq "ReceivingReply") {
719: # The send has completed. Wait for the
720: # data to come in for a reply.
721: Debug(8,"Writable sent request/receiving reply");
722: $Watcher->poll("r");
723: $Watcher->cb(\&LondReadable);
724:
725: } else {
726: # Control only passes here on an error:
727: # the socket state does not match any
728: # of the known states... so an error
729: # must be logged.
730:
731: &Debug(4, "Invalid socket state ".$State."\n");
732: }
733:
734: }
735:
736: =pod
737:
738: =head2 MakeLondConnection
739:
740: Create a new lond connection object, and start it towards its initial
741: idleness. Once idle, it becomes elligible to receive transactions
742: from the work queue. If the work queue is not empty when the
743: connection is completed and becomes idle, it will dequeue an entry and
744: start off on it.
745:
746: =cut
747:
748: sub MakeLondConnection {
749: Debug(4,"MakeLondConnection to ".GetServerHost()." on port "
750: .GetServerPort());
751:
752: my $Connection = LondConnection->new(&GetServerHost(),
753: &GetServerPort());
754:
755: if($Connection == undef) { # Needs to be more robust later.
756: die "Failed to make a connection!!".$!."\n";
757:
758: }
759: # The connection needs to have writability
760: # monitored in order to send the init sequence
761: # that starts the whole authentication/key
762: # exchange underway.
763: #
764: my $Socket = $Connection->GetSocket();
765: if($Socket == undef) {
766: die "did not get a socket from the connection";
767: } else {
768: &Debug(9,"MakeLondConnection got socket: ".$Socket);
769: }
770:
771:
772: $event = Event->io(fd => $Socket,
773: poll => 'w',
774: cb => \&LondWritable,
775: data => ($Connection, undef),
776: desc => 'Connection to lond server');
777: $ActiveConnections{$Connection} = $event;
778:
779: $ConnectionCount++;
780:
781:
782: }
783:
784: =pod
785:
786: =head2 StartRequest
787:
788: Starts a lond request going on a specified lond connection.
789: parameters are:
790:
791: =item $Lond
792:
793: Connection to the lond that will send the transaction and receive the
794: reply.
795:
796: =item $Client
797:
798: Connection to the client that is making this request We got the
799: request from this socket, and when the request has been relayed to
800: lond and we get a reply back from lond it will get sent to this
801: socket.
802:
803: =item $Request
804:
805: The text of the request to send.
806:
807: =cut
808:
809: sub StartRequest {
810: my $Lond = shift;
811: my $Client = shift;
812: my $Request = shift;
813:
814: Debug(6, "StartRequest: ".$Request);
815:
816: my $Socket = $Lond->GetSocket();
817:
818: $ActiveTransactions{$Lond} = $Client; # Socket to relay to client.
819:
820: $Lond->InitiateTransaction($Request);
821: $event = Event->io(fd => $Lond->GetSocket(),
822: poll => "w",
823: cb => \&LondWritable,
824: data => $Lond,
825: desc => "lond transaction connection");
826: $ActiveConnections{$Lond} = $event;
827: Debug(8," Start Request made watcher data with ".$event->data."\n");
828: }
829:
830: =pod
831:
832: =head2 QueueTransaction
833:
834: If there is an idle lond connection, it is put to work doing this
835: transaction. Otherwise, the transaction is placed in the work queue.
836: If placed in the work queue and the maximum number of connections has
837: not yet been created, a new connection will be started. Our goal is
838: to eventually have a sufficient number of connections that the work
839: queue will typically be empty. parameters are:
840:
841: =item Socket
842:
843: open on the lonc client.
844:
845: =item Request
846:
847: data to send to the lond.
848:
849: =cut
850:
851: sub QueueTransaction {
852: my $requestSocket = shift;
853: my $requestData = shift;
854:
855: Debug(6,"QueueTransaction: ".$requestData);
856:
857: my $LondSocket = $IdleConnections->pop();
858: if(!defined $LondSocket) { # Need to queue request.
859: Debug(8,"Must queue...");
860: $ClientQueue->enqueue($requestSocket);
861: $WorkQueue->enqueue($requestData);
862: if($ConnectionCount < $MaxConnectionCount) {
863: Debug(4,"Starting additional lond connection");
864: MakeLondConnection();
865: }
866: } else { # Can start the request:
867: Debug(8,"Can start...");
868: StartRequest($LondSocket, $requestSocket, $requestData);
869: }
870: }
871:
872: #-------------------------- Lonc UNIX socket handling ---------------------
873:
874: =pod
875:
876: =head2 ClientRequest
877:
878: Callback that is called when data can be read from the UNIX domain
879: socket connecting us with an apache server process.
880:
881: =cut
882:
883: sub ClientRequest {
884: Debug(6, "ClientRequest");
885: my $event = shift;
886: my $watcher = $event->w;
887: my $socket = $watcher->fd;
888: my $data = $watcher->data;
889: my $thisread;
890:
891: Debug(9, " Watcher named: ".$watcher->desc);
892:
893: my $rv = $socket->recv($thisread, POSIX::BUFSIZ, 0);
894: Debug(8, "rcv: data length = ".length($thisread)
895: ." read =".$thisread);
896: unless (defined $rv && length($thisread)) {
897: # Likely eof on socket.
898: Debug(5,"Client Socket closed on lonc for ".$RemoteHost);
899: close($socket);
900: $watcher->cancel();
901: delete($ActiveClients{$socket});
902: }
903: Debug(8,"Data: ".$data." this read: ".$thisread);
904: $data = $data.$thisread; # Append new data.
905: $watcher->data($data);
906: if($data =~ /(.*\n)/) { # Request entirely read.
907: Debug(8, "Complete transaction received: ".$data);
908: QueueTransaction($socket, $data);
909: $watcher->cancel(); # Done looking for input data.
910: }
911:
912: }
913:
914:
915: =pod
916:
917: =head2 NewClient
918:
919: Callback that is called when a connection is received on the unix
920: socket for a new client of lonc. The callback is parameterized by the
921: event.. which is a-priori assumed to be an io event, and therefore has
922: an fd member that is the Listener socket. We Accept the connection
923: and register a new event on the readability of that socket:
924:
925: =cut
926:
927: sub NewClient {
928: Debug(6, "NewClient");
929: my $event = shift; # Get the event parameters.
930: my $watcher = $event->w;
931: my $socket = $watcher->fd; # Get the event' socket.
932: my $connection = $socket->accept(); # Accept the client connection.
933: Debug(8,"Connection request accepted from "
934: .GetPeername($connection, AF_UNIX));
935:
936:
937: my $description = sprintf("Connection to lonc client %d",
938: $ClientConnection);
939: Debug(9, "Creating event named: ".$description);
940: Event->io(cb => \&ClientRequest,
941: poll => 'r',
942: desc => $description,
943: data => "",
944: fd => $connection);
945: $ActiveClients{$connection} = $ClientConnection;
946: $ClientConnection++;
947: }
948:
949: =pod
950:
951: =head2 GetLoncSocketPath
952:
953: Returns the name of the UNIX socket on which to listen for client
954: connections.
955:
956: =cut
957:
958: sub GetLoncSocketPath {
959: return $UnixSocketDir."/".GetServerHost();
960: }
961:
962: =pod
963:
964: =head2 GetServerHost
965:
966: Returns the host whose lond we talk with.
967:
968: =cut
969:
970: sub GetServerHost { # Stub - get this from config.
971: return $RemoteHost; # Setup by the fork.
972: }
973:
974: =pod
975:
976: =head2 GetServerPort
977:
978: Returns the lond port number.
979:
980: =cut
981:
982: sub GetServerPort { # Stub - get this from config.
983: return $perlvar{londPort};
984: }
985:
986: =pod
987:
988: =head2 SetupLoncListener
989:
990: Setup a lonc listener event. The event is called when the socket
991: becomes readable.. that corresponds to the receipt of a new
992: connection. The event handler established will accept the connection
993: (creating a communcations channel), that int turn will establish
994: another event handler to subess requests.
995:
996: =cut
997:
998: sub SetupLoncListener {
999:
1000: my $socket;
1001: my $SocketName = GetLoncSocketPath();
1002: unlink($SocketName);
1003: unless ($socket = IO::Socket::UNIX->new(Local => $SocketName,
1004: Listen => 10,
1005: Type => SOCK_STREAM)) {
1006: die "Failed to create a lonc listner socket";
1007: }
1008: Event->io(cb => \&NewClient,
1009: poll => 'r',
1010: desc => 'Lonc listener Unix Socket',
1011: fd => $socket);
1012: }
1013:
1014: =pod
1015:
1016: =head2 ChildProcess
1017:
1018: This sub implements a child process for a single lonc daemon.
1019:
1020: =cut
1021:
1022: sub ChildProcess {
1023:
1024: print "Loncnew\n";
1025:
1026: # For now turn off signals.
1027:
1028: $SIG{QUIT} = IGNORE;
1029: $SIG{HUP} = IGNORE;
1030: $SIG{USR1} = IGNORE;
1031: $SIG{INT} = IGNORE;
1032: $SIG{CHLD} = IGNORE;
1033: $SIG{__DIE__} = IGNORE;
1034:
1035: SetupTimer();
1036:
1037: SetupLoncListener();
1038:
1039: $Event::Debuglevel = $DebugLevel;
1040:
1041: Debug(9, "Making initial lond connection for ".$RemoteHost);
1042:
1043: # Setup the initial server connection:
1044:
1045: &MakeLondConnection();
1046:
1047: Debug(9,"Entering event loop");
1048: my $ret = Event::loop(); # Start the main event loop.
1049:
1050:
1051: die "Main event loop exited!!!";
1052: }
1053:
1054: # Create a new child for host passed in:
1055:
1056: sub CreateChild {
1057: my $host = shift;
1058: $RemoteHost = $host;
1059: Debug(3, "Forking off child for ".$RemoteHost);
1060: sleep(5);
1061: $pid = fork;
1062: if($pid) { # Parent
1063: $ChildHash{$pid} = $RemoteHost;
1064: } else { # child.
1065: ChildProcess;
1066: }
1067:
1068: }
1069: #
1070: # Parent process logic pass 1:
1071: # For each entry in the hosts table, we will
1072: # fork off an instance of ChildProcess to service the transactions
1073: # to that host. Each pid will be entered in a global hash
1074: # with the value of the key, the host.
1075: # The parent will then enter a loop to wait for process exits.
1076: # Each exit gets logged and the child gets restarted.
1077: #
1078:
1079: my $HostIterator = LondConnection::GetHostIterator;
1080: while (! $HostIterator->end()) {
1081:
1082: $hostentryref = $HostIterator->get();
1083: CreateChild($hostentryref->[0]);
1084: $HostIterator->next();
1085: }
1086:
1087: # Maintain the population:
1088:
1089: while(1) {
1090: $deadchild = wait();
1091: if(exists $ChildHash{$deadchild}) { # need to restart.
1092: $deadhost = $ChildHash{$deadchild};
1093: delete($ChildHash{$deadchild});
1094: Debug(4,"Lost child pid= ".$deadchild.
1095: "Connected to host ".$deadhost);
1096: CreateChild($deadhost);
1097: }
1098: }
1099:
1100: =head1 Theory
1101:
1102: The event class is used to build this as a single process with an
1103: event driven model. The following events are handled:
1104:
1105: =item UNIX Socket connection Received
1106:
1107: =item Request data arrives on UNIX data transfer socket.
1108:
1109: =item lond connection becomes writable.
1110:
1111: =item timer fires at 1 second intervals.
1112:
1113: All sockets are run in non-blocking mode. Timeouts managed by the timer
1114: handler prevents hung connections.
1115:
1116: Key data structures:
1117:
1118: =item RequestQueue
1119:
1120: A queue of requests received from UNIX sockets that are
1121: waiting for a chance to be forwarded on a lond connection socket.
1122:
1123: =item ActiveConnections
1124:
1125: A hash of lond connections that have transactions in process that are
1126: available to be timed out.
1127:
1128: =item ActiveTransactions
1129:
1130: A hash indexed by lond connections that contain the client reply
1131: socket for each connection that has an active transaction on it.
1132:
1133: =item IdleConnections
1134:
1135: A hash of lond connections that have no work to do. These connections
1136: can be closed if they are idle for a long enough time.
1137:
1138: =cut
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