Refactored using an abstraction WSF_PROTECTION.

This protection could be implemented with a regular expression,
    or using another solution (as manual parsing).
  Also, when a protection detects an issue, instead of returning empty string,
    it returns Void. If the value is a multiple string value, if an item is detected for an issue,
    the returned multiple string value is now Void.
  This abstraction will allow to return either Void, or a "corrected" value,
    for instance the string value, without the detected "<script..>..</script>" text.
  TODO: improve the WSF_PROTECTION_REGEXP to allow replacement strategy.

library/server/wsf/security/support/wsf_protection.e

@@ -0,0 +1,76 @@
+note
+	description: "Summary description for {WSF_PROTECTION}."
+	author: ""
+	date: "$Date$"
+	revision: "$Revision$"
+
+deferred class
+	WSF_PROTECTION
+
+feature -- Status report
+
+	is_valid: BOOLEAN
+		deferred
+		end
+
+feature -- String Protection
+
+	string_8 (s: READABLE_STRING_8): detachable READABLE_STRING_8
+		require
+			is_valid: is_valid
+		deferred
+		end
+
+feature -- Value Protection
+
+	value (v: WSF_VALUE): detachable WSF_VALUE
+		require
+			is_valid: is_valid
+		do
+			if attached {WSF_STRING} v as s then
+				Result := string_value (s)
+			elseif attached {WSF_MULTIPLE_STRING} v as ms then
+				Result := multiple_string_value (ms)
+			else
+					-- TODO
+				Result := v
+			end
+		end
+
+	string_value (v: WSF_STRING): detachable WSF_STRING
+		require
+			is_valid: is_valid
+		deferred
+		end
+
+	multiple_string_value (mv: WSF_MULTIPLE_STRING): detachable WSF_MULTIPLE_STRING
+		require
+			is_valid: is_valid
+		local
+			v: detachable WSF_STRING
+		do
+			across
+				mv as ic
+			loop
+				v := string_value (ic.item)
+				if v = Void then
+					Result := Void
+				elseif Result = Void then
+					create Result.make_with_value (v)
+				else
+					Result.add_value (v)
+				end
+			end
+		end
+
+note
+	copyright: "2011-2017, Jocelyn Fiat, Javier Velilla, Olivier Ligot, Colin Adams, Eiffel Software and others"
+	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
+	source: "[
+			Eiffel Software
+			5949 Hollister Ave., Goleta, CA 93117 USA
+			Telephone 805-685-1006, Fax 805-685-6869
+			Website http://www.eiffel.com
+			Customer support http://support.eiffel.com
+		]"
+end