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#
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# SpamAssassin SNF4SA Plugin for SNFServer.
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#
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# This plugin implements a SpamAssassin rule to use SNFServer to test
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# whether an email is spam.
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#
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# Copyright (C) 2009 ARM Research Labs, LLC.
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#
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# snf4sa.pm
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#
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# The plugin implements a single evaluation rule, which passes the
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# email message through SNFServer. The communication with SNFServer
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# is through XCI and a temporary file on disk which contains the email
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# message truncated to the frist 64K bytes.
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#
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package Snf4sa;
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use strict;
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use Mail::SpamAssassin;
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use Mail::SpamAssassin::Plugin;
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use Mail::SpamAssassin::PerMsgStatus;
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use IO::Socket;
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use IO::File;
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use File::Temp qw/ tempfile tempdir /;
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our @ISA = qw(Mail::SpamAssassin::Plugin);
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# Convenience variables and pseudo-constants
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my $CRLF = "\x0d\x0a";
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my $DefaultMaxTempFileSize = 64 * 1024;
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# translation table for SNF rule codes
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my $rule_code_xlat = {
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0 => 'Standard White Rules',
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20 => 'GBUdb Truncate (superblack)',
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40 => 'GBUdb Caution (suspicious)',
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47 => 'Travel',
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48 => 'Insurance',
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49 => 'Antivirus Push',
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50 => 'Media Theft',
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51 => 'Spamware',
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52 => 'Snake Oil',
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53 => 'Scam Patterns',
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54 => 'Porn/Adult',
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55 => 'Malware & Scumware Greetings',
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56 => 'Ink & Toner',
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57 => 'Get Rich',
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58 => 'Debt & Credit',
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59 => 'Casinos & Gambling',
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60 => 'Ungrouped Black Rules',
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61 => 'Experimental Abstract',
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62 => 'Obfuscation Techniques',
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63 => 'Experimental Received [ip]',
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};
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sub new {
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my ($class, $mailsa) = @_;
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$class = ref($class) || $class;
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my $self = $class->SUPER::new($mailsa);
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bless ($self, $class);
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# Name of evaluation rule.
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$self->register_eval_rule ("snf4sa_sacheck");
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# Use localhost.
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$self->{SNF_Host} = "localhost";
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# Use default port.
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$self->{SNF_Port} = 9001;
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# Timeout.
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$self->{SNF_Timeout} = 1;
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# Directory for files containing emails read by SNFServer.
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$self->{Temp_Dir} = '/tmp/snf4sa';
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# Maximum email message size (including headers).
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$self->{SNF_MaxTempFileSize} = $DefaultMaxTempFileSize;
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return $self;
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}
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sub snf4sa_sacheck {
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my ($self, $permsgstatus, $fulltext) = @_;
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my $testscore = 0;
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my $response ='';
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my $exitvalue;
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# Make sure we have a temp dir
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unless(-d $self->{Temp_Dir}) {
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mkdir($self->{Temp_Dir});
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chmod(0777, $self->{Temp_Dir});
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};
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# Truncate the message.
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my $mailtext = substr( ${$fulltext}, 0, $self->{SNF_MaxTempFileSize});
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# create our temp file, $filename will contain the full path
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my ($fh, $filename) = tempfile( DIR => $self->{Temp_Dir} );
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# spew our mail into the temp file
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my $SNF_fh = IO::File->new( $filename, "w" ) ||
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die(__PACKAGE__ . ": Unable to create temporary file '" . $filename . "'");
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$SNF_fh->print($mailtext) ||
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$self->cleanup_die($filename,
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__PACKAGE__ . ": Unable to write to temporary file '" .
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$filename . "'");
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$SNF_fh->close ||
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$self->cleanup_die($filename,
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__PACKAGE__ . ": Unable to close temporary file '" .
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$filename . "'");
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# Change permissions.
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my $cnt = chmod(0666, $filename) ||
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$self->cleanup_die($filename, __PACKAGE__ .
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": Unable to change permissions of temporary file '" .
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$filename . "'");
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# xci_scan connects to SNFServer with XCI to scan the message
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my $SNF_XCI_Return = $self->xci_scan( $filename );
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# Remove the temp file, we are done with it.
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unlink($filename);
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# Check response from SNFServer.
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if (! $SNF_XCI_Return ) {
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die(__PACKAGE__ . ": Internal error");
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}
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# Check for success.
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if (! $SNF_XCI_Return->{"success"}) {
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die(__PACKAGE__ . ": Error from SNFServer: " .
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$SNF_XCI_Return->{"message"});
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}
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# get the return code and translation
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my ( $rc, $rcx ) = ( $SNF_XCI_Return->{"code"},
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$rule_code_xlat->{ $SNF_XCI_Return->{"code"} } );
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$rc = -1 unless defined $rc; # default values
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$rcx = 'Unknown' unless $rcx;
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my $rch = $SNF_XCI_Return->{"header"}; # the SNF header(s)
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# Result code of 0 indicates non-spam. Any other value indicates
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# spam.
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if ($rc >= 1) {
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$testscore=1;
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} else {
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$testscore=0;
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}
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# Add the header.
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$permsgstatus->set_tag("SNFRESULTTAG", "$rc ($rcx)");
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#all SA cares about is whether a 0 or 1 comes back. 0 = good 1=spam.
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return $testscore;
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}
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sub abort
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{
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my ( $self, $message ) = @_;
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}
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# xci_scan( $file )
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# returns hashref:
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# success : true/false
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# code : response code from SNF
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# message : scalar message (if any)
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sub xci_scan
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{
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my ( $self, $file ) = @_;
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return undef unless $self and $file;
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my $ret_hash = {
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success => undef,
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code => undef,
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message => undef,
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header => undef,
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xml => undef
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};
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my $xci = $self->connect_socket( $self->{SNF_Host}, $self->{SNF_Port} )
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or return $self->err_hash("cannot connect to socket ($!)");
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$xci->print("<snf><xci><scanner><scan file='$file' xhdr='yes' /></scanner></xci></snf>\n");
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my $rc = $ret_hash->{xml} = $self->socket_response($xci, $file);
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$xci->close;
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if ( $rc =~ /^<snf><xci><scanner><result code='(\d*)'>/ ) {
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$ret_hash->{success} = 1;
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$ret_hash->{code} = $1;
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$rc =~ /<xhdr>(.*)<\/xhdr>/s and $ret_hash->{header} = $1;
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} elsif ( $rc =~ /^<snf><xci><error message='(.*)'/ ) {
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$ret_hash->{message} = $1;
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} else {
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$ret_hash->{message} = "unknown XCI response: $rc";
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}
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return $ret_hash;
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}
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# connect_socket( $host, $port )
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# returns IO::Socket handle
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sub connect_socket
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{
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my ( $self, $host, $port ) = @_;
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return undef unless $self and $host and $port;
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my $protoname = 'tcp'; # Proto should default to tcp but it's not expensive to specify
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$self->{XCI_Socket} = IO::Socket::INET->new(
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PeerAddr => $host,
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PeerPort => $port,
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Proto => $protoname,
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Timeout => $self->{SNF_Timeout} ) or return undef;
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$self->{XCI_Socket}->autoflush(1); # make sure autoflush is on -- legacy
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return $self->{XCI_Socket}; # return the socket handle
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}
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# socket_response( $socket_handle )
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# returns scalar string
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sub socket_response
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{
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my ( $self, $rs, $file ) = @_;
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my $buf = ''; # buffer for response
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# blocking timeout for servers who accept but don't answer
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eval {
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local $SIG{ALRM} = sub { die "timeout\n" }; # set up the interrupt
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alarm $self->{SNF_Timeout}; # set up the alarm
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while (<$rs>) { # read the socket
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$buf .= $_;
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}
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alarm 0; # reset the alarm
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};
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# report a blocking timeout
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if ( $@ eq "timeout\n" ) {
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$self->cleanup_die($file,
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__PACKAGE__ . ": Timeout waiting for response from SNFServer");
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} elsif ( $@ =~ /alarm.*unimplemented/ ) { # no signals on Win32
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while (<$rs>) { # get whatever's left
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# in the socket.
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$buf .= $_;
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}
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}
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return $buf;
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}
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# return an error message for xci_scan
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sub err_hash
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{
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my ( $self, $message ) = @_;
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return {
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success => undef,
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code => undef,
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message => $message
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};
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}
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sub cleanup_die
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{
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my ( $self, $file, $message ) = @_;
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unlink($file);
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die($message);
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}
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1;
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