+ # Only known uri schemes are allowed to avoid all the ways of
+ # embedding javascrpt.
+ # List at http://en.wikipedia.org/wiki/URI_scheme
+ my $uri_schemes=join("|",
+ # IANA registered schemes
+ "http", "https", "ftp", "mailto", "file", "telnet", "gopher",
+ "aaa", "aaas", "acap", "cap", "cid", "crid",
+ "dav", "dict", "dns", "fax", "go", "h323", "im", "imap",
+ "ldap", "mid", "news", "nfs", "nntp", "pop", "pres",
+ "sip", "sips", "snmp", "tel", "urn", "wais", "xmpp",
+ "z39.50r", "z39.50s",
+ # data is a special case. Allow data:text/<image>, but
+ # disallow data:text/javascript and everything else.
+ qr/data:text\/(?:png|gif|jpeg)/,
+ # Selected unofficial schemes
+ "about", "aim", "callto", "cvs", "ed2k", "feed", "fish", "gg",
+ "irc", "ircs", "lastfm", "ldaps", "magnet", "mms",
+ "msnim", "notes", "rsync", "secondlife", "skype", "ssh",
+ "sftp", "sms", "steam", "webcal", "ymsgr",
+ );
+ my $link=qr/^(?:$uri_schemes:|[^:]+$)/i;
+