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Up to [LON-CAPA] / loncom

Implementation of encryption
Different login mechanisms
IP Spoof Protection

#!/usr/bin/perl
# The LearningOnline Network
# lond "LON Daemon" Server (port "LOND" 5663)
# 5/26/99,6/4,6/10,6/11,6/14,6/15,6/26,6/28,6/30,
# 7/8,7/9,7/10,7/12,7/17,7/19,9/21,
# 10/7,10/8,10/9,10/11,10/13,10/15 Gerd Kortemeyer
# based on "Perl Cookbook" ISBN 1-56592-243-3
# preforker - server who forks first
# runs as a daemon
# HUPs
# uses IDEA encryption

use IO::Socket;
use IO::File;
use Apache::File;
use Symbol;
use POSIX;
use Crypt::IDEA;
use LWP::UserAgent();

# ------------------------------------ Read httpd access.conf and get variables

open (CONFIG,"/etc/httpd/conf/access.conf") || die "Can't read access.conf";

while ($configline=<CONFIG>) {
    if ($configline =~ /PerlSetVar/) {
	my ($dummy,$varname,$varvalue)=split(/\s+/,$configline);
        $perlvar{$varname}=$varvalue;
    }
}
close(CONFIG);

$PREFORK=4; # number of children to maintain, at least four spare

# ------------------------------------------------------------- Read hosts file

open (CONFIG,"$perlvar{'lonTabDir'}/hosts.tab") || die "Can't read host file";

while ($configline=<CONFIG>) {
    my ($id,$domain,$role,$name,$ip)=split(/:/,$configline);
    chomp($ip);
    $hostid{$ip}=$id;
    if ($id eq $perlvar{'lonHostID'}) { $thisserver=$name; }
    $PREFORK++;
}
close(CONFIG);

# establish SERVER socket, bind and listen.
$server = IO::Socket::INET->new(LocalPort => $perlvar{'londPort'},
                                Type      => SOCK_STREAM,
                                Proto     => 'tcp',
                                Reuse     => 1,
                                Listen    => 10 )
  or die "making socket: $@\n";

# --------------------------------------------------------- Do global variables

# global variables

$MAX_CLIENTS_PER_CHILD  = 5;        # number of clients each child should 
                                    # process
%children               = ();       # keys are current child process IDs
$children               = 0;        # current number of children

sub REAPER {                        # takes care of dead children
    $SIG{CHLD} = \&REAPER;
    my $pid = wait;
    $children --;
    &logthis("Child $pid died");
    delete $children{$pid};
}

sub HUNTSMAN {                      # signal handler for SIGINT
    local($SIG{CHLD}) = 'IGNORE';   # we're going to kill our children
    kill 'INT' => keys %children;
    my $execdir=$perlvar{'lonDaemons'};
    unlink("$execdir/logs/lond.pid");
    &logthis("Shutting down");
    exit;                           # clean up with dignity
}

sub HUPSMAN {                      # signal handler for SIGHUP
    local($SIG{CHLD}) = 'IGNORE';  # we're going to kill our children
    kill 'INT' => keys %children;
    close($server);                # free up socket
    &logthis("Restarting");
    my $execdir=$perlvar{'lonDaemons'};
    exec("$execdir/lond");         # here we go again
}

# --------------------------------------------------------------------- Logging

sub logthis {
    my $message=shift;
    my $execdir=$perlvar{'lonDaemons'};
    my $fh=IO::File->new(">>$execdir/logs/lond.log");
    my $now=time;
    my $local=localtime($now);
    print $fh "$local ($$): $message\n";
}

# ----------------------------------------------------------- Send USR1 to lonc

sub reconlonc {
    my $peerfile=shift;
    &logthis("Trying to reconnect for $peerfile");
    my $loncfile="$perlvar{'lonDaemons'}/logs/lonc.pid";
    if (my $fh=IO::File->new("$loncfile")) {
	my $loncpid=<$fh>;
        chomp($loncpid);
        if (kill 0 => $loncpid) {
	    &logthis("lonc at pid $loncpid responding, sending USR1");
            kill USR1 => $loncpid;
            sleep 1;
            if (-e "$peerfile") { return; }
            &logthis("$peerfile still not there, give it another try");
            sleep 5;
            if (-e "$peerfile") { return; }
            &logthis("$peerfile still not there, giving up");
        } else {
	    &logthis("lonc at pid $loncpid not responding, giving up");
        }
    } else {
        &logthis('lonc not running, giving up');
    }
}

# -------------------------------------------------- Non-critical communication
sub subreply {
    my ($cmd,$server)=@_;
    my $peerfile="$perlvar{'lonSockDir'}/$server";
    my $sclient=IO::Socket::UNIX->new(Peer    =>"$peerfile",
                                      Type    => SOCK_STREAM,
                                      Timeout => 10)
       or return "con_lost";
    print $sclient "$cmd\n";
    my $answer=<$sclient>;
    chomp($answer);
    if (!$answer) { $answer="con_lost"; }
    return $answer;
}

sub reply {
  my ($cmd,$server)=@_;
  my $answer;
  if ($server ne $perlvar{'lonHostID'}) { 
    $answer=subreply($cmd,$server);
    if ($answer eq 'con_lost') {
	$answer=subreply("ping",$server);
        if ($answer ne $server) {
           &reconlonc("$perlvar{'lonSockDir'}/$server");
        }
        $answer=subreply($cmd,$server);
    }
  } else {
    $answer='self_reply';
  } 
  return $answer;
}

# -------------------------------------------- Return path to profile directory
sub propath {
    my ($udom,$uname)=@_;
    $udom=~s/\W//g;
    $uname=~s/\W//g;
    my $subdir=$uname;
    $subdir =~ s/(.)(.)(.).*/$1\/$2\/$3/;
    my $proname="$perlvar{'lonUsersDir'}/$udom/$subdir/$uname";
    return $proname;
} 

# --------------------------------------- Is this the home server of an author?
sub ishome {
    my $author=shift;
    $author=~s/\/home\/httpd\/html\/res\/([^\/]*)\/([^\/]*).*/$1\/$2/;
    my ($udom,$uname)=split(/\//,$author);
    my $proname=propath($udom,$uname);
    if (-e $proname) {
	return 'owner';
    } else {
        return 'not_owner';
    }
}

# ======================================================= Continue main program
# ---------------------------------------------------- Fork once and dissociate

$fpid=fork;
exit if $fpid;
die "Couldn't fork: $!" unless defined ($fpid);

POSIX::setsid() or die "Can't start new session: $!";

# ------------------------------------------------------- Write our PID on disk

$execdir=$perlvar{'lonDaemons'};
open (PIDSAVE,">$execdir/logs/lond.pid");
print PIDSAVE "$$\n";
close(PIDSAVE);
&logthis("Starting");

# ------------------------------------------------------- Now we are on our own
    
# Fork off our children.
for (1 .. $PREFORK) {
    make_new_child();
}

# ----------------------------------------------------- Install signal handlers

$SIG{CHLD} = \&REAPER;
$SIG{INT}  = $SIG{TERM} = \&HUNTSMAN;
$SIG{HUP}  = \&HUPSMAN;

# And maintain the population.
while (1) {
    sleep;                          # wait for a signal (i.e., child's death)
    for ($i = $children; $i < $PREFORK; $i++) {
        make_new_child();           # top up the child pool
    }
}

sub make_new_child {
    my $pid;
    my $cipher;
    my $sigset;
    &logthis("Attempting to start child");    
    # block signal for fork
    $sigset = POSIX::SigSet->new(SIGINT);
    sigprocmask(SIG_BLOCK, $sigset)
        or die "Can't block SIGINT for fork: $!\n";
    
    die "fork: $!" unless defined ($pid = fork);
    
    if ($pid) {
        # Parent records the child's birth and returns.
        sigprocmask(SIG_UNBLOCK, $sigset)
            or die "Can't unblock SIGINT for fork: $!\n";
        $children{$pid} = 1;
        $children++;
        return;
    } else {
        # Child can *not* return from this subroutine.
        $SIG{INT} = 'DEFAULT';      # make SIGINT kill us as it did before
    
        # unblock signals
        sigprocmask(SIG_UNBLOCK, $sigset)
            or die "Can't unblock SIGINT for fork: $!\n";
    
        # handle connections until we've reached $MAX_CLIENTS_PER_CHILD
        for ($i=0; $i < $MAX_CLIENTS_PER_CHILD; $i++) {
            $client = $server->accept()     or last;

# =============================================================================
            # do something with the connection
# -----------------------------------------------------------------------------
            # see if we know client and check for spoof IP by challenge
            my $caller=getpeername($client);
            my ($port,$iaddr)=unpack_sockaddr_in($caller);
            my $clientip=inet_ntoa($iaddr);
            my $clientrec=($hostid{$clientip} ne undef);
            &logthis("Connect from $clientip ($hostid{$clientip})");
            my $clientok;
            if ($clientrec) {
	      my $remotereq=<$client>;
              $remotereq=~s/\W//g;
              if ($remotereq eq 'init') {
		  my $challenge="$$".time;
                  print $client "$challenge\n";
                  $remotereq=<$client>;
                  $remotereq=~s/\W//g;
                  if ($challenge eq $remotereq) {
		      $clientok=1;
                      print $client "ok\n";
                  } else {
		      &logthis("$clientip did not reply challenge");
                  }
              } else {
		  &logthis("$clientip failed to initialize: >$remotereq<");
              }
	    } else {
              &logthis("Unknown client $clientip");
            }
            if ($clientok) {
# ---------------- New known client connecting, could mean machine online again
	      &reconlonc("$perlvar{'lonSockDir'}/$hostid{$clientip}");
# ------------------------------------------------------------ Process requests
              while (my $userinput=<$client>) {
                chomp($userinput);
                my $wasenc=0;
# ------------------------------------------------------------ See if encrypted
		if ($userinput =~ /^enc/) {
		  if ($cipher) {
                    my ($cmd,$cmdlength,$encinput)=split(/:/,$userinput);
		    $userinput='';
                    for (my $encidx=0;$encidx<length($encinput);$encidx+=16) {
                       $userinput.=
			   $cipher->decrypt(
                            pack("H16",substr($encinput,$encidx,16))
                           );
		    }
		    $userinput=substr($userinput,0,$cmdlength);
                    $wasenc=1;
		  }
		}
# ------------------------------------------------------------- Normal commands
# ------------------------------------------------------------------------ ping
		   if ($userinput =~ /^ping/) {
                       print $client "$perlvar{'lonHostID'}\n";
# ------------------------------------------------------------------------ pong
		   } elsif ($userinput =~ /^pong/) {
                       $reply=reply("ping",$hostid{$clientip});
                       print $client "$perlvar{'lonHostID'}:$reply\n"; 
# ------------------------------------------------------------------------ ekey
		   } elsif ($userinput =~ /^ekey/) {
                       my $buildkey=time.$$.int(rand 100000);
                       $buildkey=~tr/1-6/A-F/;
                       $buildkey=int(rand 100000).$buildkey.int(rand 100000);
                       my $key=$perlvar{'lonHostID'}.$hostid{$clientip};
                       $key=~tr/a-z/A-Z/;
                       $key=~tr/G-P/0-9/;
                       $key=~tr/Q-Z/0-9/;
                       $key=$key.$buildkey.$key.$buildkey.$key.$buildkey;
                       $key=substr($key,0,32);
                       my $cipherkey=pack("H32",$key);
                       $cipher=new IDEA $cipherkey;
                       print $client "$buildkey\n"; 
# ------------------------------------------------------------------------ load
		   } elsif ($userinput =~ /^load/) {
                       my $loadavg;
                       {
                          my $loadfile=IO::File->new('/proc/loadavg');
                          $loadavg=<$loadfile>;
                       }
                       $loadavg =~ s/\s.*//g;
                       my $loadpercent=100*$loadavg/$perlvar{'lonLoadLim'};
		       print $client "$loadpercent\n";
# ------------------------------------------------------------------------ auth
                   } elsif ($userinput =~ /^auth/) {
		     if ($wasenc==1) {
                       my ($cmd,$udom,$uname,$upass)=split(/:/,$userinput);
                       chomp($upass);
                       my $proname=propath($udom,$uname);
                       my $passfilename="$proname/passwd";
                       if (-e $passfilename) {
                          my $pf = IO::File->new($passfilename);
                          my $realpasswd=<$pf>;
                          chomp($realpasswd);
                          my ($howpwd,$contentpwd)=split(/:/,$realpasswd);
                          my $pwdcorrect=0;
                          if ($howpwd eq 'internal') {
			      $pwdcorrect=
				  (crypt($upass,$contentpwd) eq $contentpwd);
                          } elsif ($howpwd eq 'unix') {
                              $contentpwd=(getpwnam($uname))[1];
                              $pwdcorrect=
                                  (crypt($upass,$contentpwd) eq $contentpwd);
                          }
                          if ($pwdcorrect) {
                             print $client "authorized\n";
                          } else {
                             print $client "non_authorized\n";
                          }  
		       } else {
                          print $client "unknown_user\n";
                       }
		     } else {
		       print $client "refused\n";
		     }
# ---------------------------------------------------------------------- passwd
                   } elsif ($userinput =~ /^passwd/) {
		     if ($wasenc==1) {
                       my 
                       ($cmd,$udom,$uname,$upass,$npass)=split(/:/,$userinput);
                       chomp($npass);
                       my $proname=propath($udom,$uname);
                       my $passfilename="$proname/passwd";
                       if (-e $passfilename) {
			   my $realpasswd;
                          { my $pf = IO::File->new($passfilename);
			    $realpasswd=<$pf>; }
                          chomp($realpasswd);
                          my ($howpwd,$contentpwd)=split(/:/,$realpasswd);
                          if ($howpwd eq 'internal') {
			   if (crypt($upass,$contentpwd) eq $contentpwd) {
			     my $salt=time;
                             $salt=substr($salt,6,2);
			     my $ncpass=crypt($npass,$salt);
                             { my $pf = IO::File->new(">$passfilename");
 	  		       print $pf "internal:$ncpass\n";; }             
                             print $client "ok\n";
                           } else {
                             print $client "non_authorized\n";
                           }
                          } else {
                            print $client "auth_mode_error\n";
                          }  
		       } else {
                          print $client "unknown_user\n";
                       }
		     } else {
		       print $client "refused\n";
		     }
# ------------------------------------------------------------------------ home
                   } elsif ($userinput =~ /^home/) {
                       my ($cmd,$udom,$uname)=split(/:/,$userinput);
                       chomp($uname);
                       my $proname=propath($udom,$uname);
                       if (-e $proname) {
                          print $client "found\n";
                       } else {
			  print $client "not_found\n";
                       }
# ---------------------------------------------------------------------- update
                   } elsif ($userinput =~ /^update/) {
                       my ($cmd,$fname)=split(/:/,$userinput);
                       my $ownership=ishome($fname);
                       if ($ownership eq 'not_owner') {
                        if (-e $fname) {
                          my ($dev,$ino,$mode,$nlink,
                              $uid,$gid,$rdev,$size,
                              $atime,$mtime,$ctime,
                              $blksize,$blocks)=stat($fname);
                          $now=time;
                          $since=$now-$atime;
                          if ($since>$perlvar{'lonExpire'}) {
                              $reply=
                                    reply("unsub:$fname","$hostid{$clientip}");
                              unlink("$fname");
                          } else {
			     my $transname="$fname.in.transfer";
                             my $remoteurl=
                                    reply("sub:$fname","$hostid{$clientip}");
                             my $response;
                              {
                             my $ua=new LWP::UserAgent;
                             my $request=new HTTP::Request('GET',"$remoteurl");
                             $response=$ua->request($request,$transname);
			      }
                             if ($response->is_error()) {
				 unline($transname);
                                 my $message=$response->status_line;
                                 &logthis(
                                  "LWP GET: $message for $fname ($remoteurl)");
                             } else {
                                 rename($transname,$fname);
			     }
                          }
                          print $client "ok\n";
                        } else {
                          print $client "not_found\n";
                        }
		       } else {
			print $client "rejected\n";
                       }
# ----------------------------------------------------------------- unsubscribe
                   } elsif ($userinput =~ /^unsub/) {
                       my ($cmd,$fname)=split(/:/,$userinput);
                       if (-e $fname) {
                           if (unlink("$fname.$hostid{$clientip}")) {
                              print $client "ok\n";
			   } else {
                              print $client "not_subscribed\n";
			   }
                       } else {
			   print $client "not_found\n";
                       }
# ------------------------------------------------------------------- subscribe
                   } elsif ($userinput =~ /^sub/) {
                       my ($cmd,$fname)=split(/:/,$userinput);
                       my $ownership=ishome($fname);
                       if ($ownership eq 'owner') {
                        if (-e $fname) {
                           $now=time;
                           { 
                            my $sh=IO::File->new(">$fname.$hostid{$clientip}");
                            print $sh "$clientip:$now\n";
			   }
                           $fname=~s/\/home\/httpd\/html\/res/raw/;
                           $fname="http://$thisserver/".$fname;
                           print $client "$fname\n";
                        } else {
		      	   print $client "not_found\n";
                        }
		       } else {
                        print $client "rejected\n";
		       }
# ------------------------------------------------------------------------- put
                   } elsif ($userinput =~ /^put/) {
                       my ($cmd,$udom,$uname,$namespace,$what)
                          =split(/:/,$userinput);
                       $namespace=~s/\W//g;
                       chomp($what);
                       my $proname=propath($udom,$uname);
                       my $now=time;
                       {
			   my $hfh;
			   if (
                             $hfh=IO::File->new(">>$proname/$namespace.hist")
			       ) { print $hfh "P:$now:$what\n"; }
		       }
                       my @pairs=split(/\&/,$what);
                       if (dbmopen(%hash,"$proname/$namespace.db",0644)) {
                           foreach $pair (@pairs) {
			       ($key,$value)=split(/=/,$pair);
                               $hash{$key}=$value;
                           }
			   if (dbmclose(%hash)) {
                              print $client "ok\n";
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
# ------------------------------------------------------------------------- get
                   } elsif ($userinput =~ /^get/) {
                       my ($cmd,$udom,$uname,$namespace,$what)
                          =split(/:/,$userinput);
                       $namespace=~s/\W//g;
                       chomp($what);
                       my @queries=split(/\&/,$what);
                       my $proname=propath($udom,$uname);
                       my $qresult='';
                       if (dbmopen(%hash,"$proname/$namespace.db",0644)) {
                           for ($i=0;$i<=$#queries;$i++) {
                               $qresult.="$hash{$queries[$i]}&";
                           }
			   if (dbmclose(%hash)) {
		              $qresult=~s/\&$//;
                              print $client "$qresult\n";
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
# ------------------------------------------------------------------------ eget
                   } elsif ($userinput =~ /^eget/) {
                       my ($cmd,$udom,$uname,$namespace,$what)
                          =split(/:/,$userinput);
                       $namespace=~s/\W//g;
                       chomp($what);
                       my @queries=split(/\&/,$what);
                       my $proname=propath($udom,$uname);
                       my $qresult='';
                       if (dbmopen(%hash,"$proname/$namespace.db",0644)) {
                           for ($i=0;$i<=$#queries;$i++) {
                               $qresult.="$hash{$queries[$i]}&";
                           }
			   if (dbmclose(%hash)) {
		              $qresult=~s/\&$//;
                              if ($cipher) {
                                my $cmdlength=length($qresult);
                                $qresult.="         ";
                                my $encqresult='';
                                for 
				(my $encidx=0;$encidx<=$cmdlength;$encidx+=8) {
                                 $encqresult.=
                                 unpack("H16",
                                 $cipher->encrypt(substr($qresult,$encidx,8)));
                                }
                                print $client "enc:$cmdlength:$encqresult\n";
			      } else {
			        print $client "error:no_key\n";
                              }
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
# ------------------------------------------------------------------------- del
                   } elsif ($userinput =~ /^del/) {
                       my ($cmd,$udom,$uname,$namespace,$what)
                          =split(/:/,$userinput);
                       $namespace=~s/\W//g;
                       chomp($what);
                       my $proname=propath($udom,$uname);
                       my $now=time;
                       {
			   my $hfh;
			   if (
                             $hfh=IO::File->new(">>$proname/$namespace.hist")
			       ) { print $hfh "D:$now:$what\n"; }
		       }
                       my @keys=split(/\&/,$what);
                       if (dbmopen(%hash,"$proname/$namespace.db",0644)) {
                           foreach $key (@keys) {
                               delete($hash{$key});
                           }
			   if (dbmclose(%hash)) {
                              print $client "ok\n";
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
# ------------------------------------------------------------------------ keys
                   } elsif ($userinput =~ /^keys/) {
                       my ($cmd,$udom,$uname,$namespace)
                          =split(/:/,$userinput);
                       $namespace=~s/\W//g;
                       chomp($namespace);
                       my $proname=propath($udom,$uname);
                       my $qresult='';
                       if (dbmopen(%hash,"$proname/$namespace.db",0644)) {
                           foreach $key (keys %hash) {
                               $qresult.="$key&";
                           }
			   if (dbmclose(%hash)) {
		              $qresult=~s/\&$//;
                              print $client "$qresult\n";
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
# ------------------------------------------------------------------------ dump
                   } elsif ($userinput =~ /^dump/) {
                       my ($cmd,$udom,$uname,$namespace)
                          =split(/:/,$userinput);
                       $namespace=~s/\W//g;
                       chomp($namespace);
                       my $proname=propath($udom,$uname);
                       my $qresult='';
                       if (dbmopen(%hash,"$proname/$namespace.db",0644)) {
                           foreach $key (keys %hash) {
                               $qresult.="$key=$hash{$key}&";
                           }
			   if (dbmclose(%hash)) {
		              $qresult=~s/\&$//;
                              print $client "$qresult\n";
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
# ----------------------------------------------------------------------- idput
                   } elsif ($userinput =~ /^idput/) {
                       my ($cmd,$udom,$what)=split(/:/,$userinput);
                       chomp($what);
                       $udom=~s/\W//g;
                       my $proname="$perlvar{'lonUsersDir'}/$udom/ids";
                       my $now=time;
                       {
			   my $hfh;
			   if (
                             $hfh=IO::File->new(">>$proname.hist")
			       ) { print $hfh "P:$now:$what\n"; }
		       }
                       my @pairs=split(/\&/,$what);
                       if (dbmopen(%hash,"$proname.db",0644)) {
                           foreach $pair (@pairs) {
			       ($key,$value)=split(/=/,$pair);
                               $hash{$key}=$value;
                           }
			   if (dbmclose(%hash)) {
                              print $client "ok\n";
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
# ----------------------------------------------------------------------- idget
                   } elsif ($userinput =~ /^idget/) {
                       my ($cmd,$udom,$what)=split(/:/,$userinput);
                       chomp($what);
                       $udom=~s/\W//g;
                       my $proname="$perlvar{'lonUsersDir'}/$udom/ids";
                       my @queries=split(/\&/,$what);
                       my $qresult='';
                       if (dbmopen(%hash,"$proname.db",0644)) {
                           for ($i=0;$i<=$#queries;$i++) {
                               $qresult.="$hash{$queries[$i]}&";
                           }
			   if (dbmclose(%hash)) {
		              $qresult=~s/\&$//;
                              print $client "$qresult\n";
                           } else {
                              print $client "error:$!\n";
                           }
                       } else {
                           print $client "error:$!\n";
                       }
# ------------------------------------------------------------- unknown command
                   } else {
                       # unknown command
                       print $client "unknown_cmd\n";
                   }
# ------------------------------------------------------ client unknown, refuse
	       }
            } else {
	        print $client "refused\n";
                &logthis("Rejected client $clientip, closing connection");
            }              
            &logthis("Disconnect from $clientip ($hostid{$clientip})");
# =============================================================================
        }
    
        # tidy up gracefully and finish
    
        # this exit is VERY important, otherwise the child will become
        # a producer of more and more children, forking yourself into
        # process death.
        exit;
    }
}