add virus checking to attachments plugin

IkiWiki/Plugin/attachment.pm

@@ -333,6 +333,44 @@ sub match_mimetype ($$;@) { #{{{
 	}
 } #}}}
 
+sub match_virusfree ($$;@) { #{{{
+	shift;
+	my $wanted=shift;
+
+	my %params=@_;
+	if (! exists $params{file}) {
+		return IkiWiki::FailReason->new("no file specified");
+	}
+
+	if (! exists $IkiWiki::config{virus_checker} ||
+	    ! length $IkiWiki::config{virus_checker}) {
+		return IkiWiki::FailReason->new("no virus_checker configured");
+	}
+
+	# The file needs to be fed into the virus checker on stdin,
+	# because the file is not world-readable, and if clamdscan is
+	# used, clamd would fail to read it.
+	eval q{use IPC::Open2};
+	error($@) if $@;
+	open (IN, "<", $params{file}) || return IkiWiki::FailReason->new("failed to read file");
+	binmode(IN);
+	my $sigpipe=0;
+	$SIG{PIPE} = sub { $sigpipe=1 };
+	my $pid=open2(\*CHECKER_OUT, "<&IN", $IkiWiki::config{virus_checker}); 
+	my $reason=<CHECKER_OUT>;
+	chomp $reason;
+	1 while (<CHECKER_OUT>);
+	close(CHECKER_OUT);
+	waitpid $pid, 0;
+	$SIG{PIPE}="DEFAULT";
+	if ($sigpipe || $?) {
+		return IkiWiki::FailReason->new("file seems to contain a virus ($reason)");
+	}
+	else {
+		return IkiWiki::SuccessReason->new("file seems virusfree ($reason)");
+	}
+} #}}}
+
 sub match_ispage ($$;@) { #{{{
 	my $filename=shift;
 

debian/changelog

@@ -1,6 +1,9 @@
 ikiwiki (2.52) UNRELEASED; urgency=low
 
   * attachment: New plugin for uploading and managing attachments.
+    This includes a fairly powerful PageSpec based admin pref for deciding
+    whether to accept a given upload, and an attachment management interface
+    on the edit page.
     (Sponsored by The TOVA Company.)
   * If attachments are not enabled, configure CGI.pm to disable file
     uploads by default. (An anti-DOS measure.)

doc/ikiwiki.setup

@@ -195,4 +195,8 @@ use IkiWiki::Setup::Standard {
 	#amazon_s3_location => "EU",
 	# Uncomment if you need to store each index file twice.
 	#amazon_s3_dupindex => 1,
+	
+	# For use with the attachment plugin, a program that returns
+	# nonzero if its standard input contains an virus.
+	#virus_checker => "clamdscan -",
 }

doc/ikiwiki/pagespec/attachment.mdwn

@@ -8,10 +8,10 @@ attachments will be accepted, by entering a [[ikiwiki/PageSpec]] in the
 "Allowed Attachments" field of their preferences page.
 
 For example, to limit arbitrary files to 50 kilobytes, but allow
-larger mp3 files to be uploaded by joey, a something like this could be
+larger mp3 files to be uploaded by joey, and check all attachments for
-used:
+virii, something like this could be used:
   
-	(user(joey) and *.mp3 and mimetype(audio/mpeg) and maxsize(15mb)) or (!ispage() and maxsize(50kb))
+	virusfree() and ((user(joey) and *.mp3 and mimetype(audio/mpeg) and maxsize(15mb)) or (!ispage() and maxsize(50kb)))
 
 The regular [[ikiwiki/PageSpec]] syntax is expanded with thw following
 additional tests:
@@ -50,3 +50,7 @@ additional tests:
 
   This checks the MIME type of the attachment. You can include a glob
   in the type, for example `mimetype(image/*)`.
+
+* virusfree()
+
+  Checks the attachment with an antiviral program.

doc/plugins/attachment.mdwn

@@ -26,3 +26,9 @@ Attachments" field of the wiki admin's preferences page.
 
 This plugin will use the [[cpan File::MimeInfo::Magic]] perl module, if
 available, for mimetype checking.
+
+The `virusfree` [[PageSpec|ikiwiki/pagespec/attachment]] requires that
+ikiwiki be configured with a virus scanner program via the `virus_checker`
+option in the setup file. If using `clamav`, with `clamd`, set it to
+"clamdscan -". Or to use clamav without the `clamd` daemon, you
+could set it to "clamscan -".

doc/todo/attachments.mdwn

@@ -1,15 +1,9 @@
 Stuff the [[plugins/attachment]] plugin is currently missing, that might be
 nice to add:
 
-* Virus scanning.
 * Add a progress bar for attachment uploads (needs AJAX stuff..)
 * Maybe optimise the "Insert Links" button with javascript, so, if
   javascript is available, the link is inserted at the current cursor
   position in the page edit form, without actually reposting the form.
   (Falling back to the current reposting of the form if javascript is not
   available of course.)
-* Set `$CGI::POST_MAX` to some sane value (ie, larger than the largest
-  configured `maxsize()` in the pagespec, or if none is configured,
-  something reasonable. Just as a belt-and-suspenders DOS prevention.
-* Only allow attachments to be added to a given list of pages.
-  Maybe a pagespec like `parent(patches/*)`