Annotation of loncom/LondConnection.pm, revision 1.19

1.2       albertel    1: #   This module defines and implements a class that represents
                      2: #   a connection to a lond daemon.
                      3: #
1.19    ! albertel    4: # $Id: LondConnection.pm,v 1.18 2003/12/02 10:38:40 foxr Exp $
1.2       albertel    5: #
                      6: # Copyright Michigan State University Board of Trustees
                      7: #
                      8: # This file is part of the LearningOnline Network with CAPA (LON-CAPA).
                      9: #
                     10: # LON-CAPA is free software; you can redistribute it and/or modify
                     11: # it under the terms of the GNU General Public License as published by
                     12: # the Free Software Foundation; either version 2 of the License, or
                     13: # (at your option) any later version.
                     14: #
                     15: # LON-CAPA is distributed in the hope that it will be useful,
                     16: # but WITHOUT ANY WARRANTY; without even the implied warranty of
                     17: # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
                     18: # GNU General Public License for more details.
                     19: #
                     20: # You should have received a copy of the GNU General Public License
                     21: # along with LON-CAPA; if not, write to the Free Software
                     22: # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
                     23: #
                     24: # /home/httpd/html/adm/gpl.txt
                     25: #
                     26: # http://www.lon-capa.org/
1.1       foxr       27: #
1.14      foxr       28: 
1.1       foxr       29: package LondConnection;
                     30: 
1.10      foxr       31: use strict;
1.1       foxr       32: use IO::Socket;
                     33: use IO::Socket::INET;
                     34: use IO::Handle;
                     35: use IO::File;
                     36: use Fcntl;
                     37: use POSIX;
                     38: use Crypt::IDEA;
1.14      foxr       39: 
1.1       foxr       40: 
1.12      foxr       41: 
                     42: 
                     43: 
1.6       foxr       44: my $DebugLevel=0;
1.12      foxr       45: my %hostshash;
                     46: my %perlvar;
1.1       foxr       47: 
1.14      foxr       48: #
1.16      foxr       49: #  Set debugging level
                     50: #
                     51: sub SetDebug {
                     52:     $DebugLevel = shift;
                     53: }
                     54: 
                     55: #
1.14      foxr       56: #   The config read is done in this way to support the read of
                     57: #   the non-default configuration file in the
                     58: #   event we are being used outside of loncapa.
                     59: #
                     60: 
                     61: my $ConfigRead = 0;
                     62: 
1.1       foxr       63: #   Read the configuration file for apache to get the perl
                     64: #   variable set.
                     65: 
1.12      foxr       66: sub ReadConfig {
1.14      foxr       67:     my $perlvarref = read_conf('loncapa.conf');
1.12      foxr       68:     %perlvar    = %{$perlvarref};
1.14      foxr       69:     my $hoststab   = read_hosts(
                     70: 				"$perlvar{'lonTabDir'}/hosts.tab") || 
                     71: 				die "Can't read host table!!";
1.12      foxr       72:     %hostshash  = %{$hoststab};
1.17      foxr       73:     $ConfigRead = 1;
1.12      foxr       74:     
                     75: }
                     76: 
1.15      foxr       77: #
                     78: #  Read a foreign configuration.
                     79: #  This sub is intended for the cases where the package
                     80: #  will be read from outside the LonCAPA environment, in that case
                     81: #  the client will need to explicitly provide:
                     82: #   - A file in hosts.tab format.
                     83: #   - Some idea of the 'lonCAPA' name of the local host (for building
                     84: #     the encryption key).
                     85: #
                     86: #  Parameters:
                     87: #      MyHost   - Name of this host as far as LonCAPA is concerned.
                     88: #      Filename - Name of a hosts.tab formatted file that will be used
                     89: #                 to build up the hosts table.
                     90: #
                     91: sub ReadForeignConfig {
                     92:     my $MyHost   = shift;
                     93:     my $Filename = shift;
                     94: 
1.17      foxr       95:     &Debug(4, "ReadForeignConfig $MyHost $Filename\n");
                     96: 
1.15      foxr       97:     $perlvar{lonHostID} = $MyHost; # Rmember my host.
                     98:     my $hosttab = read_hosts($Filename) ||
                     99: 	die "Can't read hosts table!!";
1.17      foxr      100:     %hostshash = %{$hosttab};
                    101:     if($DebugLevel > 3) {
                    102: 	foreach my $host (keys %hostshash) {
                    103: 	    print "host $host => $hostshash{$host}\n";
                    104: 	}
                    105:     }
                    106:     $ConfigRead = 1;
1.1       foxr      107: 
1.15      foxr      108: }
1.1       foxr      109: 
                    110: sub Debug {
                    111:     my $level   = shift;
                    112:     my $message = shift;
                    113:     if ($level < $DebugLevel) {
                    114: 	print($message."\n");
                    115:     }
                    116: }
1.3       albertel  117: 
                    118: =pod
                    119: 
                    120: =head2 Dump
                    121: 
1.12      foxr      122: Dump the internal state of the object: For debugging purposes, to stderr.
1.3       albertel  123: 
1.1       foxr      124: =cut
                    125: 
                    126: sub Dump {
                    127:     my $self   = shift;
1.10      foxr      128:     my $key;
                    129:     my $value;
1.1       foxr      130:     print "Dumping LondConnectionObject:\n";
                    131:     while(($key, $value) = each %$self) {
1.19    ! albertel  132: 	print "$key -> $value\n";
1.1       foxr      133:     }
                    134:     print "-------------------------------\n";
                    135: }
                    136: 
                    137: =pod
1.3       albertel  138: 
                    139: Local function to do a state transition.  If the state transition
                    140: callback is defined it is called with two parameters: the self and the
                    141: old state.
                    142: 
1.1       foxr      143: =cut
1.3       albertel  144: 
1.1       foxr      145: sub Transition {
                    146:     my $self     = shift;
                    147:     my $newstate = shift;
                    148:     my $oldstate = $self->{State};
                    149:     $self->{State} = $newstate;
                    150:     $self->{TimeoutRemaining} = $self->{TimeoutValue};
                    151:     if($self->{TransitionCallback}) {
                    152: 	($self->{TransitionCallback})->($self, $oldstate); 
                    153:     }
                    154: }
                    155: 
1.3       albertel  156: 
1.14      foxr      157: 
1.1       foxr      158: =pod
1.3       albertel  159: 
                    160: =head2 new
                    161: 
                    162: Construct a new lond connection.
                    163: 
                    164: Parameters (besides the class name) include:
                    165: 
                    166: =item hostname
                    167: 
                    168: host the remote lond is on. This host is a host in the hosts.tab file
                    169: 
                    170: =item port
                    171: 
                    172:  port number the remote lond is listening on.
                    173: 
1.1       foxr      174: =cut
1.3       albertel  175: 
1.1       foxr      176: sub new {
                    177:     my $class    = shift;	# class name.
                    178:     my $Hostname = shift;	# Name of host to connect to.
                    179:     my $Port     = shift;	# Port to connect 
1.14      foxr      180: 
                    181:     if (!$ConfigRead) {
                    182: 	ReadConfig();
                    183: 	$ConfigRead = 1;
                    184:     }
1.1       foxr      185:     &Debug(4,$class."::new( ".$Hostname.",".$Port.")\n");
                    186: 
                    187:     # The host must map to an entry in the hosts table:
                    188:     #  We connect to the dns host that corresponds to that
                    189:     #  system and use the hostname for the encryption key 
                    190:     #  negotion.  In the objec these become the Host and
                    191:     #  LoncapaHim fields of the object respectively.
                    192:     #
                    193:     if (!exists $hostshash{$Hostname}) {
1.16      foxr      194: 	&Debug(8, "No Such host $Hostname");
1.1       foxr      195: 	return undef;		# No such host!!!
                    196:     }
                    197:     my @ConfigLine = @{$hostshash{$Hostname}};
                    198:     my $DnsName    = $ConfigLine[3]; # 4'th item is dns of host.
                    199:     Debug(5, "Connecting to ".$DnsName);
                    200:     # Now create the object...
                    201:     my $self     = { Host               => $DnsName,
                    202: 		     LoncapaHim         => $Hostname,
                    203: 	             Port               => $Port,
                    204: 	             State              => "Initialized",
                    205: 	             TransactionRequest => "",
                    206: 	             TransactionReply   => "",
                    207: 	             InformReadable     => 0,
                    208: 	             InformWritable     => 0,
                    209: 		     TimeoutCallback    => undef,
                    210: 		     TransitionCallback => undef,
                    211: 	             Timeoutable        => 0,
1.9       foxr      212: 	             TimeoutValue       => 30,
                    213: 		     TimeoutRemaining   => 0,
1.1       foxr      214: 		     CipherKey          => "",
                    215: 		     Cipher             => undef};
                    216:     bless($self, $class);
                    217:     unless ($self->{Socket} = IO::Socket::INET->new(PeerHost => $self->{Host},
                    218: 					       PeerPort => $self->{Port},
                    219: 					       Type     => SOCK_STREAM,
1.8       foxr      220: 					       Proto    => "tcp",
1.13      foxr      221: 					       Timeout  => 3)) {
1.1       foxr      222: 	return undef;		# Inidicates the socket could not be made.
                    223:     }
                    224:     #
                    225:     # We're connected.  Set the state, and the events we'll accept:
                    226:     #
                    227:     $self->Transition("Connected");
                    228:     $self->{InformWritable}     = 1;    # When  socket is writable we send init
1.9       foxr      229:     $self->{Timeoutable}        = 1;    # Timeout allowed during startup negotiation. 
1.1       foxr      230:     $self->{TransactionRequest} = "init\n";
                    231:     
                    232:     #
                    233:     # Set socket to nonblocking I/O.
                    234:     #
                    235:     my $socket = $self->{Socket};
1.10      foxr      236:     my $flags    = fcntl($socket->fileno, F_GETFL,0);
1.1       foxr      237:     if($flags == -1) {
                    238: 	$socket->close;
                    239: 	return undef;
                    240:     }
                    241:     if(fcntl($socket, F_SETFL, $flags | O_NONBLOCK) == -1) {
                    242: 	$socket->close;
                    243: 	return undef;
                    244:     }
                    245: 
                    246:     # return the object :
                    247: 
                    248:     return $self;
                    249: }
1.3       albertel  250: 
1.1       foxr      251: =pod
1.3       albertel  252: 
                    253: =head2 Readable
                    254: 
                    255: This member should be called when the Socket becomes readable.  Until
                    256: the read completes, action is state independet. Data are accepted into
                    257: the TransactionReply until a newline character is received.  At that
                    258: time actionis state dependent:
                    259: 
                    260: =item Connected
                    261: 
                    262: in this case we received challenge, the state changes to
                    263: ChallengeReceived, and we initiate a send with the challenge response.
                    264: 
                    265: =item ReceivingReply
                    266: 
                    267: In this case a reply has been received for a transaction, the state
                    268: goes to Idle and we disable write and read notification.
                    269: 
                    270: =item ChallengeReeived
                    271: 
                    272: we just got what should be an ok\n and the connection can now handle
                    273: transactions.
1.1       foxr      274: 
                    275: =cut
1.3       albertel  276: 
1.1       foxr      277: sub Readable {
                    278:     my $self    = shift;
                    279:     my $socket  = $self->{Socket};
                    280:     my $data    = '';
                    281:     my $rv      = $socket->recv($data, POSIX::BUFSIZ,  0);
                    282:     my $errno   = $! + 0;	             # Force numeric context.
                    283: 
1.8       foxr      284:     unless (defined($rv) && length $data) {# Read failed,
1.1       foxr      285: 	if(($errno == POSIX::EWOULDBLOCK)   ||
                    286: 	   ($errno == POSIX::EAGAIN)        ||
1.8       foxr      287: 	   ($errno == POSIX::EINTR)) {
1.1       foxr      288: 	    return 0;
                    289: 	}
                    290: 
                    291: 	# Connection likely lost.
                    292: 	&Debug(4, "Connection lost");
                    293: 	$self->{TransactionRequest} = '';
                    294: 	$socket->close();
                    295: 	$self->Transition("Disconnected");
                    296: 	return -1;
                    297:     }
                    298:     #  Append the data to the buffer.  And figure out if the read is done:
                    299: 
                    300:     &Debug(9,"Received from host: ".$data);
                    301:     $self->{TransactionReply} .= $data;
                    302:     if($self->{TransactionReply} =~ /(.*\n)/) {
                    303: 	&Debug(8,"Readable End of line detected");
                    304: 	if ($self->{State}  eq "Initialized") { # We received the challenge:
1.10      foxr      305: 	    if($self->{TransactionReply} eq "refused\n") {	# Remote doesn't have
1.1       foxr      306: 		
                    307: 		$self->Transition("Disconnected"); # in host tables.
                    308: 		$socket->close();
                    309: 		return -1;
                    310: 	    }
                    311: 
                    312: 	    &Debug(8," Transition out of Initialized");
                    313: 	    $self->{TransactionRequest} = $self->{TransactionReply};
                    314: 	    $self->{InformWritable}     = 1;
                    315: 	    $self->{InformReadable}     = 0;
                    316: 	    $self->Transition("ChallengeReceived");
                    317: 	    $self->{TimeoutRemaining}   = $self->{TimeoutValue};
                    318: 	    return 0;
                    319: 	} elsif ($self->{State} eq "ChallengeReplied") { # should be ok.
                    320: 	    if($self->{TransactionReply} != "ok\n") {
                    321: 		$self->Transition("Disconnected");
                    322: 		$socket->close();
                    323: 		return -1;
                    324: 	    }
                    325: 	    $self->Transition("RequestingKey");
                    326: 	    $self->{InformReadable}  = 0;
                    327: 	    $self->{InformWritable}  = 1;
                    328: 	    $self->{TransactionRequest} = "ekey\n";
                    329: 	    return 0;
                    330: 	} elsif ($self->{State}  eq "ReceivingKey") {
                    331: 	    my $buildkey = $self->{TransactionReply};
                    332: 	    my $key = $self->{LoncapaHim}.$perlvar{'lonHostID'};
                    333: 	    $key=~tr/a-z/A-Z/;
                    334: 	    $key=~tr/G-P/0-9/;
                    335: 	    $key=~tr/Q-Z/0-9/;
                    336: 	    $key=$key.$buildkey.$key.$buildkey.$key.$buildkey;
                    337: 	    $key=substr($key,0,32);
                    338: 	    my $cipherkey=pack("H32",$key);
                    339: 	    $self->{Cipher} = new IDEA $cipherkey;
1.13      foxr      340: 	    if($self->{Cipher} eq undef) {
1.1       foxr      341: 		$self->Transition("Disconnected");
                    342: 		$socket->close();
                    343: 		return -1;
                    344: 	    } else {
                    345: 		$self->Transition("Idle");
                    346: 		$self->{InformWritable}  =  0;
                    347: 		$self->{InformReadable}  =  0;
                    348: 		$self->{Timeoutable}     = 0;
                    349: 		return 0;
                    350: 	    }
                    351: 	} elsif ($self->{State}  eq "ReceivingReply") {
                    352: 
                    353: 	    # If the data are encrypted, decrypt first.
                    354: 
                    355: 	    my $answer = $self->{TransactionReply};
                    356: 	    if($answer =~ /^enc\:/) {
                    357: 		$answer = $self->Decrypt($answer);
                    358: 		$self->{TransactionReply} = $answer;
                    359: 	    }
                    360: 
                    361: 	    # finish the transaction
                    362: 
                    363: 	    $self->{InformWritable}     = 0;
                    364: 	    $self->{InformReadable}     = 0;
                    365: 	    $self->{Timeoutable}        = 0;
                    366: 	    $self->Transition("Idle");
                    367: 	    return 0;
                    368: 	} elsif ($self->{State} eq "Disconnected") { # No connection.
                    369: 	    return -1;
                    370: 	} else {			# Internal error: Invalid state.
                    371: 	    $self->Transition("Disconnected");
                    372: 	    $socket->close();
                    373: 	    return -1;
                    374: 	}
                    375:     }
                    376: 
                    377:     return 0;
                    378:     
                    379: }
                    380: 
                    381: 
                    382: =pod
1.3       albertel  383: 
                    384: This member should be called when the Socket becomes writable.
                    385: 
                    386: The action is state independent. An attempt is made to drain the
                    387: contents of the TransactionRequest member.  Once this is drained, we
                    388: mark the object as waiting for readability.
1.1       foxr      389: 
                    390: Returns  0 if successful, or -1 if not.
1.3       albertel  391: 
1.1       foxr      392: =cut
                    393: sub Writable {
                    394:     my $self     = shift;		# Get reference to the object.
                    395:     my $socket   = $self->{Socket};
                    396:     my $nwritten = $socket->send($self->{TransactionRequest}, 0);
                    397:     my $errno    = $! + 0;
                    398:     unless (defined $nwritten) {
                    399: 	if($errno != POSIX::EINTR) {
                    400: 	    $self->Transition("Disconnected");
                    401: 	    return -1;
                    402: 	}
                    403:       
                    404:     }
1.10      foxr      405:     if (($nwritten >= 0)                        ||
1.1       foxr      406:         ($errno == POSIX::EWOULDBLOCK)    ||
                    407: 	($errno == POSIX::EAGAIN)         ||
                    408: 	($errno == POSIX::EINTR)          ||
                    409: 	($errno ==  0)) {
                    410: 	substr($self->{TransactionRequest}, 0, $nwritten) = ""; # rmv written part
                    411: 	if(length $self->{TransactionRequest} == 0) {
                    412: 	    $self->{InformWritable} = 0;
                    413: 	    $self->{InformReadable} = 1;
                    414: 	    $self->{TransactionReply} = '';
                    415: 	    #
                    416: 	    # Figure out the next state:
                    417: 	    #
                    418: 	    if($self->{State} eq "Connected") {
                    419: 		$self->Transition("Initialized");
                    420: 	    } elsif($self->{State} eq "ChallengeReceived") {
                    421: 		$self->Transition("ChallengeReplied");
                    422: 	    } elsif($self->{State} eq "RequestingKey") {
                    423: 		$self->Transition("ReceivingKey");
                    424: 		$self->{InformWritable} = 0;
                    425: 		$self->{InformReadable} = 1;
                    426: 		$self->{TransactionReply} = '';
                    427: 	    } elsif ($self->{State} eq "SendingRequest") {
                    428: 		$self->Transition("ReceivingReply");
                    429: 		$self->{TimeoutRemaining} = $self->{TimeoutValue};
                    430: 	    } elsif ($self->{State} eq "Disconnected") {
                    431: 		return -1;
                    432: 	    }
                    433: 	    return 0;
                    434: 	}
                    435:     } else {			# The write failed (e.g. partner disconnected).
                    436: 	$self->Transition("Disconnected");
                    437: 	$socket->close();
                    438: 	return -1;
                    439:     }
                    440: 	
                    441: }
                    442: =pod
1.3       albertel  443: 
                    444: =head2 Tick
                    445: 
1.1       foxr      446:    Tick is called every time unit by the event framework.  It
1.3       albertel  447: 
                    448: =item 1 decrements the remaining timeout.
                    449: 
                    450: =item 2 If the timeout is zero, calls TimedOut indicating that the current operation timed out.
1.1       foxr      451: 
                    452: =cut
                    453:     
                    454: sub Tick {
                    455:     my $self = shift;
                    456:     $self->{TimeoutRemaining}--;
                    457:     if ($self->{TimeoutRemaining} < 0) {
                    458: 	$self->TimedOut();
                    459:     }
                    460: }
1.3       albertel  461: 
1.1       foxr      462: =pod
                    463: 
1.3       albertel  464: =head2 TimedOut
                    465: 
                    466: called on a timeout.  If the timeout callback is defined, it is called
                    467: with $self as its parameters.
                    468: 
                    469: =cut
                    470: 
1.1       foxr      471: sub TimedOut  {
                    472: 
                    473:     my $self = shift;
                    474:     if($self->{TimeoutCallback}) {
                    475: 	my $callback = $self->{TimeoutCallback};
                    476: 	my @args = ( $self);
                    477: 	&$callback(@args);
                    478:     }
                    479: }
1.3       albertel  480: 
1.1       foxr      481: =pod
1.3       albertel  482: 
                    483: =head2 InitiateTransaction
                    484: 
                    485: Called to initiate a transaction.  A transaction can only be initiated
                    486: when the object is idle... otherwise an error is returned.  A
                    487: transaction consists of a request to the server that will have a
                    488: reply.  This member sets the request data in the TransactionRequest
                    489: member, makes the state SendingRequest and sets the data to allow a
                    490: timout, and to request writability notification.
                    491: 
1.1       foxr      492: =cut
1.3       albertel  493: 
1.1       foxr      494: sub InitiateTransaction {
                    495:     my $self   = shift;
                    496:     my $data   = shift;
                    497: 
1.4       foxr      498:     Debug(1, "initiating transaction: ".$data);
1.1       foxr      499:     if($self->{State} ne "Idle") {
1.4       foxr      500: 	Debug(0," .. but not idle here\n");
1.1       foxr      501: 	return -1;		# Error indicator.
                    502:     }
                    503:     # if the transaction is to be encrypted encrypt the data:
                    504: 
                    505:     if($data =~ /^encrypt\:/) {
                    506: 	$data = $self->Encrypt($data);
                    507:     }
                    508: 
                    509:     # Setup the trasaction
                    510: 
                    511:     $self->{TransactionRequest} = $data;
                    512:     $self->{TransactionReply}   = "";
                    513:     $self->{InformWritable}     = 1;
                    514:     $self->{InformReadable}     = 0;
                    515:     $self->{Timeoutable}        = 1;
                    516:     $self->{TimeoutRemaining}   = $self->{TimeoutValue};
                    517:     $self->Transition("SendingRequest");
                    518: }
                    519: 
                    520: 
                    521: =pod
1.3       albertel  522: 
                    523: =head2 SetStateTransitionCallback
                    524: 
                    525: Sets a callback for state transitions.  Returns a reference to any
                    526: prior established callback, or undef if there was none:
                    527: 
1.1       foxr      528: =cut
1.3       albertel  529: 
1.1       foxr      530: sub SetStateTransitionCallback {
                    531:     my $self        = shift;
                    532:     my $oldCallback = $self->{TransitionCallback};
                    533:     $self->{TransitionCallback} = shift;
                    534:     return $oldCallback;
                    535: }
1.3       albertel  536: 
1.1       foxr      537: =pod
1.3       albertel  538: 
                    539: =head2 SetTimeoutCallback
                    540: 
                    541: Sets the timeout callback.  Returns a reference to any prior
                    542: established callback or undef if there was none.
                    543: 
1.1       foxr      544: =cut
1.3       albertel  545: 
1.1       foxr      546: sub SetTimeoutCallback {
                    547:     my $self                 = shift;
                    548:     my $callback             = shift;
                    549:     my $oldCallback          = $self->{TimeoutCallback};
                    550:     $self->{TimeoutCallback} = $callback;
                    551:     return $oldCallback;
                    552: }
                    553: 
                    554: =pod
1.3       albertel  555: 
1.5       foxr      556: =head2 Shutdown:
                    557: 
                    558: Shuts down the socket.
                    559: 
                    560: =cut
                    561: 
                    562: sub Shutdown {
                    563:     my $self = shift;
                    564:     my $socket = $self->GetSocket();
1.18      foxr      565:     $socket->send("exit\n", 0);	# Ask lond to exit too.  Non blocking so
                    566:                                 # there's no cost for failure.
1.5       foxr      567:     $socket->shutdown(2);
                    568: }
                    569: 
                    570: =pod
                    571: 
1.3       albertel  572: =head2 GetState
                    573: 
                    574: selector for the object state.
                    575: 
1.1       foxr      576: =cut
1.3       albertel  577: 
1.1       foxr      578: sub GetState {
                    579:     my $self = shift;
                    580:     return $self->{State};
                    581: }
1.3       albertel  582: 
1.1       foxr      583: =pod
1.3       albertel  584: 
                    585: =head2 GetSocket
                    586: 
                    587: selector for the object socket.
                    588: 
1.1       foxr      589: =cut
1.3       albertel  590: 
1.1       foxr      591: sub GetSocket {
                    592:     my $self  = shift;
                    593:     return $self->{Socket};
                    594: }
1.3       albertel  595: 
1.5       foxr      596: 
1.1       foxr      597: =pod
1.3       albertel  598: 
                    599: =head2 WantReadable
                    600: 
                    601: Return the state of the flag that indicates the object wants to be
                    602: called when readable.
                    603: 
1.1       foxr      604: =cut
1.3       albertel  605: 
1.1       foxr      606: sub WantReadable {
                    607:     my   $self = shift;
                    608: 
                    609:     return $self->{InformReadable};
                    610: }
1.3       albertel  611: 
1.1       foxr      612: =pod
1.3       albertel  613: 
                    614: =head2 WantWritable
                    615: 
                    616: Return the state of the flag that indicates the object wants write
                    617: notification.
                    618: 
1.1       foxr      619: =cut
1.3       albertel  620: 
1.1       foxr      621: sub WantWritable {
                    622:     my $self = shift;
                    623:     return $self->{InformWritable};
                    624: }
1.3       albertel  625: 
1.1       foxr      626: =pod
1.3       albertel  627: 
                    628: =head2 WantTimeout
                    629: 
                    630: return the state of the flag that indicates the object wants to be
                    631: informed of timeouts.
                    632: 
1.1       foxr      633: =cut
1.3       albertel  634: 
1.1       foxr      635: sub WantTimeout {
                    636:     my $self = shift;
                    637:     return $self->{Timeoutable};
                    638: }
                    639: 
                    640: =pod
1.3       albertel  641: 
                    642: =head2 GetReply
                    643: 
                    644: Returns the reply from the last transaction.
                    645: 
1.1       foxr      646: =cut
1.3       albertel  647: 
1.1       foxr      648: sub GetReply {
                    649:     my $self = shift;
                    650:     return $self->{TransactionReply};
                    651: }
                    652: 
                    653: =pod
1.3       albertel  654: 
                    655: =head2 Encrypt
                    656: 
                    657: Returns the encrypted version of the command string.
                    658: 
                    659: The command input string is of the form:
                    660: 
1.1       foxr      661:   encrypt:command
1.3       albertel  662: 
                    663: The output string can be directly sent to lond as it is of the form:
                    664: 
1.1       foxr      665:   enc:length:<encodedrequest>
1.3       albertel  666: 
1.1       foxr      667: =cut
1.3       albertel  668: 
1.1       foxr      669: sub Encrypt {
                    670:     my $self    = shift;		# Reference to the object.
                    671:     my $request = shift;	        # Text to send.
                    672: 
                    673:    
                    674:     # Split the encrypt: off the request and figure out it's length.
                    675:     # the cipher works in blocks of 8 bytes.
                    676: 
                    677:     my $cmd = $request;
                    678:     $cmd    =~ s/^encrypt\://;	# strip off encrypt:
                    679:     chomp($cmd);		# strip off trailing \n
                    680:     my     $length=length($cmd);	# Get the string length.
                    681:     $cmd .= "         ";	# Pad with blanks so we can fill out a block.
                    682: 
                    683:     # encrypt the request in 8 byte chunks to create the encrypted
                    684:     # output request.
                    685: 
                    686:     my $Encoded = '';
                    687:     for(my $index = 0; $index <= $length; $index += 8) {
                    688: 	$Encoded .= 
                    689: 	    unpack("H16", 
                    690: 		   $self->{Cipher}->encrypt(substr($cmd, 
                    691: 						   $index, 8)));
                    692:     }
                    693: 
                    694:     # Build up the answer as enc:length:$encrequest.
                    695: 
                    696:     $request = "enc:$length:$Encoded\n";
                    697:     return $request;
                    698:     
                    699:     
                    700: }
1.3       albertel  701: 
                    702: =pod
                    703: 
                    704: =head2 Decrypt
                    705: 
                    706: Decrypt a response from the server.  The response is in the form:
                    707: 
                    708:  enc:<length>:<encrypted data>
                    709: 
1.1       foxr      710: =cut
1.3       albertel  711: 
1.1       foxr      712: sub Decrypt {
                    713:     my $self      = shift;	# Recover reference to object
                    714:     my $encrypted = shift;	# This is the encrypted data.
                    715: 
                    716:     #  Bust up the response into length, and encryptedstring:
                    717: 
                    718:     my ($enc, $length, $EncryptedString) = split(/:/,$encrypted);
                    719:     chomp($EncryptedString);
                    720: 
                    721:     # Decode the data in 8 byte blocks.  The string is encoded
                    722:     # as hex digits so there are two characters per byte:
                    723: 
1.10      foxr      724:     my $decrypted = "";
1.1       foxr      725:     for(my $index = 0; $index < length($EncryptedString);
                    726: 	$index += 16) {
                    727: 	$decrypted .= $self->{Cipher}->decrypt(
                    728: 				    pack("H16",
                    729: 					 substr($EncryptedString,
                    730: 						$index, 
                    731: 						16)));
                    732:     }
                    733:     #  the answer may have trailing pads to fill out a block.
                    734:     #  $length tells us the actual length of the decrypted string:
                    735: 
                    736:     $decrypted = substr($decrypted, 0, $length);
                    737: 
                    738:     return $decrypted;
                    739: 
                    740: }
                    741: 
                    742: =pod
1.3       albertel  743: 
                    744: =head2 GetHostIterator
1.1       foxr      745: 
                    746: Returns a hash iterator to the host information.  Each get from 
                    747: this iterator returns a reference to an array that contains 
                    748: information read from the hosts configuration file.  Array elements
                    749: are used as follows:
                    750: 
1.3       albertel  751:  [0]   - LonCapa host name.
                    752:  [1]   - LonCapa domain name.
                    753:  [2]   - Loncapa role (e.g. library or access).
                    754:  [3]   - DNS name server hostname.
1.11      foxr      755:  [4]   - IP address (result of e.g. nslookup [3]).
1.3       albertel  756:  [5]   - Maximum connection count.
                    757:  [6]   - Idle timeout for reducing connection count.
                    758:  [7]   - Minimum connection count.
1.1       foxr      759: 
1.3       albertel  760: =cut
1.1       foxr      761: 
                    762: sub GetHostIterator {
                    763: 
                    764:     return HashIterator->new(\%hostshash);    
                    765: }
1.14      foxr      766: 
                    767: ###########################################################
                    768: #
                    769: #  The following is an unashamed kludge that is here to
                    770: # allow LondConnection to be used outside of the
                    771: # loncapa environment (e.g. by lonManage).
                    772: # 
                    773: #   This is a textual inclusion of pieces of the
                    774: #   Configuration.pm module.
                    775: #
                    776: 
                    777: 
                    778: my $confdir='/etc/httpd/conf/';
                    779: 
                    780: # ------------------- Subroutine read_conf: read LON-CAPA server configuration.
                    781: # This subroutine reads PerlSetVar values out of specified web server
                    782: # configuration files.
                    783: sub read_conf
                    784:   {
                    785:     my (@conf_files)=@_;
                    786:     my %perlvar;
                    787:     foreach my $filename (@conf_files,'loncapa_apache.conf')
                    788:       {
                    789: 	open(CONFIG,'<'.$confdir.$filename) or
                    790: 	    die("Can't read $confdir$filename");
                    791: 	while (my $configline=<CONFIG>)
                    792: 	  {
                    793: 	    if ($configline =~ /^[^\#]*PerlSetVar/)
                    794: 	      {
                    795: 		my ($unused,$varname,$varvalue)=split(/\s+/,$configline);
                    796: 		chomp($varvalue);
                    797: 		$perlvar{$varname}=$varvalue;
                    798: 	      }
                    799: 	  }
                    800: 	close(CONFIG);
                    801:       }
                    802:     my $perlvarref=\%perlvar;
                    803:     return ($perlvarref);
                    804:   }
                    805: 
                    806: #---------------------- Subroutine read_hosts: Read a LON-CAPA hosts.tab
                    807: # formatted configuration file.
                    808: #
                    809: my $RequiredCount = 5;		# Required item count in hosts.tab.
                    810: my $DefaultMaxCon = 5;		# Default value for maximum connections.
                    811: my $DefaultIdle   = 1000;       # Default connection idle time in seconds.
                    812: my $DefaultMinCon = 0;          # Default value for minimum connections.
                    813: 
                    814: sub read_hosts {
                    815:     my $Filename = shift;
                    816:     my %HostsTab;
                    817:     
1.16      foxr      818:    open(CONFIG,'<'.$Filename) or die("Can't read $Filename");
1.14      foxr      819:     while (my $line = <CONFIG>) {
                    820: 	if (!($line =~ /^\s*\#/)) {
                    821: 	    my @items = split(/:/, $line);
                    822: 	    if(scalar @items >= $RequiredCount) {
                    823: 		if (scalar @items == $RequiredCount) { # Only required items:
                    824: 		    $items[$RequiredCount] = $DefaultMaxCon;
                    825: 		}
                    826: 		if(scalar @items == $RequiredCount + 1) { # up through maxcon.
                    827: 		    $items[$RequiredCount+1] = $DefaultIdle;
                    828: 		}
                    829: 		if(scalar @items == $RequiredCount + 2) { # up through idle.
                    830: 		    $items[$RequiredCount+2] = $DefaultMinCon;
                    831: 		}
                    832: 		{
                    833: 		    my @list = @items; # probably not needed but I'm unsure of 
                    834: 		    # about the scope of item so...
                    835: 		    $HostsTab{$list[0]} = \@list; 
                    836: 		}
                    837: 	    }
                    838: 	}
                    839:     }
                    840:     close(CONFIG);
                    841:     my $hostref = \%HostsTab;
                    842:     return ($hostref);
                    843: }
                    844: 
1.1       foxr      845: 
                    846: 1;
                    847: 
                    848: =pod
1.3       albertel  849: 
1.1       foxr      850: =head1 Theory
                    851: 
1.3       albertel  852: The lond object is a state machine.  It lives through the following states:
                    853: 
                    854: =item Connected:
                    855: 
                    856: a TCP connection has been formed, but the passkey has not yet been
                    857: negotiated.
                    858: 
                    859: =item Initialized:
                    860: 
                    861: "init" sent.
                    862: 
                    863: =item ChallengeReceived:
                    864: 
                    865: lond sent its challenge to us.
                    866: 
                    867: =item ChallengeReplied:
                    868: 
                    869: We replied to lond's challenge waiting for lond's ok.
                    870: 
                    871: =item RequestingKey:
                    872: 
                    873: We are requesting an encryption key.
                    874: 
                    875: =item ReceivingKey:
                    876: 
                    877: We are receiving an encryption key.
                    878: 
                    879: =item Idle:
                    880: 
                    881: Connection was negotiated but no requests are active.
                    882: 
                    883: =item SendingRequest:
                    884: 
                    885: A request is being sent to the peer.
                    886: 
                    887: =item ReceivingReply:
                    888: 
                    889: Waiting for an entire reply from the peer.
                    890: 
                    891: =item Disconnected:
                    892: 
                    893: For whatever reason, the connection was dropped.
                    894: 
                    895: When we need to be writing data, we have a writable event. When we
                    896: need to be reading data, a readable event established.  Events
                    897: dispatch through the class functions Readable and Writable, and the
                    898: watcher contains a reference to the associated object to allow object
                    899: context to be reached.
1.1       foxr      900: 
                    901: =head2 Member data.
                    902: 
1.3       albertel  903: =item Host
                    904: 
                    905: Host socket is connected to.
                    906: 
                    907: =item Port
                    908: 
                    909: The port the remote lond is listening on.
                    910: 
                    911: =item Socket
                    912: 
                    913: Socket open on the connection.
                    914: 
                    915: =item State
                    916: 
                    917: The current state.
                    918: 
                    919: =item TransactionRequest
                    920: 
                    921: The request being transmitted.
                    922: 
                    923: =item TransactionReply
                    924: 
                    925: The reply being received from the transaction.
                    926: 
                    927: =item InformReadable
                    928: 
                    929: True if we want to be called when socket is readable.
                    930: 
                    931: =item InformWritable
                    932: 
                    933: True if we want to be informed if the socket is writable.
                    934: 
                    935: =item Timeoutable
                    936: 
                    937: True if the current operation is allowed to timeout.
                    938: 
                    939: =item TimeoutValue
                    940: 
                    941: Number of seconds in the timeout.
                    942: 
                    943: =item TimeoutRemaining
                    944: 
                    945: Number of seconds left in the timeout.
                    946: 
                    947: =item CipherKey
                    948: 
                    949: The key that was negotiated with the peer.
                    950: 
                    951: =item Cipher
                    952: 
                    953: The cipher obtained via the key.
1.1       foxr      954: 
                    955: 
                    956: =head2 The following are callback like members:
1.3       albertel  957: 
                    958: =item Tick:
                    959: 
                    960: Called in response to a timer tick. Used to managed timeouts etc.
                    961: 
                    962: =item Readable:
                    963: 
                    964: Called when the socket becomes readable.
                    965: 
                    966: =item Writable:
                    967: 
                    968: Called when the socket becomes writable.
                    969: 
                    970: =item TimedOut:
                    971: 
                    972: Called when a timed operation timed out.
                    973: 
1.1       foxr      974: 
                    975: =head2 The following are operational member functions.
1.3       albertel  976: 
                    977: =item InitiateTransaction:
                    978: 
                    979: Called to initiate a new transaction
                    980: 
                    981: =item SetStateTransitionCallback:
                    982: 
                    983: Called to establish a function that is called whenever the object goes
                    984: through a state transition.  This is used by The client to manage the
                    985: work flow for the object.
                    986: 
                    987: =item SetTimeoutCallback:
                    988: 
                    989: Set a function to be called when a transaction times out.  The
                    990: function will be called with the object as its sole parameter.
                    991: 
                    992: =item Encrypt:
                    993: 
                    994: Encrypts a block of text according to the cipher negotiated with the
                    995: peer (assumes the text is a command).
                    996: 
                    997: =item Decrypt:
                    998: 
                    999: Decrypts a block of text according to the cipher negotiated with the
                   1000: peer (assumes the block was a reply.
1.5       foxr     1001: 
                   1002: =item Shutdown:
                   1003: 
                   1004: Shuts off the socket.
1.1       foxr     1005: 
                   1006: =head2 The following are selector member functions:
                   1007: 
1.3       albertel 1008: =item GetState:
                   1009: 
                   1010: Returns the current state
                   1011: 
                   1012: =item GetSocket:
                   1013: 
                   1014: Gets the socekt open on the connection to lond.
                   1015: 
                   1016: =item WantReadable:
                   1017: 
                   1018: true if the current state requires a readable event.
                   1019: 
                   1020: =item WantWritable:
                   1021: 
                   1022: true if the current state requires a writable event.
                   1023: 
                   1024: =item WantTimeout:
                   1025: 
                   1026: true if the current state requires timeout support.
                   1027: 
                   1028: =item GetHostIterator:
                   1029: 
                   1030: Returns an iterator into the host file hash.
                   1031: 
1.1       foxr     1032: =cut

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