WebUI: prohibit strange special characters in password

Restricts password to A-Z, a-z, 0-9 and !#$%()*+,.:;=?@^_

Fixes #40

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>
Tested-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>
Reviewed-by: Tim Niemeyer <tim@tn-x.org>

src/packages/fff/fff-web/files/www/ssl/cgi-bin/password.html

@@ -3,8 +3,12 @@
 <%
 # write
 if [ "$REQUEST_METHOD" == "POST" ] ; then
+	#check for special characters in password
+	regex='^[a-zA-Z0-9!#\$%\(\)\*\+,\.:;=\?@\^_]+$'
 	if [ "$POST_pass1" == "" ] ; then
 		MSG='<span class="red">Das Passwort darf nicht leer sein!</span>'
+    elif ! echo -n "$POST_pass1" | egrep -q "$regex"; then   
+		MSG='<span class="red">Passwort enth&auml;lt ung&uuml;ltige Zeichen!</span>'
 	else
 		(echo "$POST_pass1"; sleep 1; echo "$POST_pass2") | passwd &>/dev/null
 		if [ $? -eq 0 ]; then