+ if (! defined wantarray) {
+ # avoid collecting duplicate data during scan pass
+ return;
+ }
+
+ # Metadata handling that happens only during preprocessing pass.
+ if ($key eq 'permalink') {
+ if (safeurl($value)) {
+ push @{$metaheaders{$page}}, scrub('<link rel="bookmark" href="'.encode_entities($value).'" />', $page, $destpage);
+ }
+ }
+ elsif ($key eq 'stylesheet') {
+ my $rel=exists $params{rel} ? $params{rel} : "alternate stylesheet";
+ my $title=exists $params{title} ? $params{title} : $value;
+ # adding .css to the value prevents using any old web
+ # editable page as a stylesheet
+ my $stylesheet=bestlink($page, $value.".css");
+ if (! length $stylesheet) {
+ error gettext("stylesheet not found")
+ }
+ push @{$metaheaders{$page}}, scrub('<link href="'.urlto($stylesheet, $page).
+ '" rel="'.encode_entities($rel).
+ '" title="'.encode_entities($title).
+ "\" type=\"text/css\" />", $page, $destpage);
+ }
+ elsif ($key eq 'script') {
+ my $defer=exists $params{defer} ? ' defer="defer"' : '';
+ my $async=exists $params{async} ? ' async="async"' : '';
+ my $js=bestlink($page, $value.".js");
+ if (! length $js) {
+ error gettext("script not found");
+ }
+ push @{$metaheaders{$page}}, scrub('<script src="'.urlto($js, $page).
+ '"' . $defer . $async . ' type="text/javascript"></script>',
+ $page, $destpage);
+ }
+ elsif ($key eq 'openid') {
+ my $delegate=0; # both by default
+ if (exists $params{delegate}) {
+ $delegate = 1 if lc $params{delegate} eq 'openid';
+ $delegate = 2 if lc $params{delegate} eq 'openid2';
+ }
+ if (exists $params{server} && safeurl($params{server})) {
+ push @{$metaheaders{$page}}, '<link href="'.encode_entities($params{server}).
+ '" rel="openid.server" />' if $delegate ne 2;
+ push @{$metaheaders{$page}}, '<link href="'.encode_entities($params{server}).
+ '" rel="openid2.provider" />' if $delegate ne 1;
+ }
+ if (safeurl($value)) {
+ push @{$metaheaders{$page}}, '<link href="'.encode_entities($value).
+ '" rel="openid.delegate" />' if $delegate ne 2;
+ push @{$metaheaders{$page}}, '<link href="'.encode_entities($value).
+ '" rel="openid2.local_id" />' if $delegate ne 1;
+ }
+ if (exists $params{"xrds-location"} && safeurl($params{"xrds-location"})) {
+ # force url absolute
+ eval q{use URI};
+ error($@) if $@;
+ my $url=URI->new_abs($params{"xrds-location"}, $config{url});
+ push @{$metaheaders{$page}}, '<meta http-equiv="X-XRDS-Location" '.
+ 'content="'.encode_entities($url).'" />';
+ }
+ }
+ elsif ($key eq 'foaf') {
+ if (safeurl($value)) {
+ push @{$metaheaders{$page}}, '<link rel="meta" '.
+ 'type="application/rdf+xml" title="FOAF" '.
+ 'href="'.encode_entities($value).'" />';
+ }
+ }
+ elsif ($key eq 'redir') {
+ return "" if $page ne $destpage;
+ my $safe=0;
+ if ($value !~ /^\w+:\/\//) {
+ my ($redir_page, $redir_anchor) = split /\#/, $value;
+
+ my $link=bestlink($page, $redir_page);
+ if (! length $link) {
+ error gettext("redir page not found")
+ }
+ add_depends($page, $link, deptype("presence"));
+
+ $value=urlto($link, $page);
+ $value.='#'.$redir_anchor if defined $redir_anchor;
+ $safe=1;
+
+ # redir cycle detection
+ $pagestate{$page}{meta}{redir}=$link;
+ my $at=$page;
+ my %seen;
+ while (exists $pagestate{$at}{meta}{redir}) {
+ if ($seen{$at}) {
+ error gettext("redir cycle is not allowed")
+ }
+ $seen{$at}=1;
+ $at=$pagestate{$at}{meta}{redir};
+ }
+ }
+ else {
+ $value=encode_entities($value);
+ }
+ my $delay=int(exists $params{delay} ? $params{delay} : 0);
+ my $redir="<meta http-equiv=\"refresh\" content=\"$delay; URL=$value\" />";
+ if (! $safe) {
+ $redir=scrub($redir, $page, $destpage);
+ }
+ push @{$metaheaders{$page}}, $redir;
+ }
+ elsif ($key eq 'link') {
+ if (%params) {
+ push @{$metaheaders{$page}}, scrub("<link href=\"".encode_entities($value)."\" ".
+ join(" ", map {
+ encode_entities($_)."=\"".encode_entities(decode_entities($params{$_}))."\""
+ } keys %params).
+ " />\n", $page, $destpage);
+ }
+ }
+ elsif ($key eq 'robots') {
+ push @{$metaheaders{$page}}, '<meta name="robots"'.
+ ' content="'.encode_entities($value).'" />';
+ }
+ elsif ($key eq 'description' || $key eq 'author') {
+ push @{$metaheaders{$page}}, '<meta name="'.$key.
+ '" content="'.encode_entities($value).'" />';
+ }
+ elsif ($key eq 'name') {
+ push @{$metaheaders{$page}}, scrub('<meta name="'.
+ encode_entities($value).
+ join(' ', map { "$_=\"$params{$_}\"" } keys %params).
+ ' />', $page, $destpage);
+ }
+ elsif ($key eq 'keywords') {
+ # Make sure the keyword string is safe: only allow alphanumeric
+ # characters, space and comma and strip the rest.
+ $value =~ s/[^[:alnum:], ]+//g;
+ push @{$metaheaders{$page}}, '<meta name="keywords"'.
+ ' content="'.encode_entities($value).'" />';
+ }
+ else {
+ push @{$metaheaders{$page}}, scrub('<meta name="'.
+ encode_entities($key).'" content="'.
+ encode_entities($value).'" />', $page, $destpage);
+ }
+