util/caps.lua

-- Prosody IM

-- Copyright (C) 2008-2010 Matthew Wild

-- Copyright (C) 2008-2010 Waqas Hussain

-- 

-- This project is MIT/X11 licensed. Please see the

-- COPYING file in the source package for more information.

--

local base64 = require "util.encodings".base64.encode;

local sha1 = require "util.hashes".sha1;

local t_insert, t_sort, t_concat = table.insert, table.sort, table.concat;

local ipairs = ipairs;

module "caps"

function calculate_hash(disco_info)

	local identities, features, extensions = {}, {}, {};

	for _, tag in ipairs(disco_info) do

		if tag.name == "identity" then

			t_insert(identities, (tag.attr.category or "").."\0"..(tag.attr.type or "").."\0"..(tag.attr["xml:lang"] or "").."\0"..(tag.attr.name or ""));

		elseif tag.name == "feature" then

			t_insert(features, tag.attr.var or "");

		elseif tag.name == "x" and tag.attr.xmlns == "jabber:x:data" then

			local form = {};

			local FORM_TYPE;

			for _, field in ipairs(tag.tags) do

				if field.name == "field" and field.attr.var then

					local values = {};

					for _, val in ipairs(field.tags) do

						val = #val.tags == 0 and val:get_text();

						if val then t_insert(values, val); end

					end

					t_sort(values);

					if field.attr.var == "FORM_TYPE" then

						FORM_TYPE = values[1];

					elseif #values > 0 then

						t_insert(form, field.attr.var.."\0"..t_concat(values, "<"));

					else

						t_insert(form, field.attr.var);

					end

				end

			end

			t_sort(form);

			form = t_concat(form, "<");

			if FORM_TYPE then form = FORM_TYPE.."\0"..form; end

			t_insert(extensions, form);

		end

	end

	t_sort(identities);

	t_sort(features);

	t_sort(extensions);

	if #identities > 0 then identities = t_concat(identities, "<"):gsub("%z", "/").."<"; else identities = ""; end

	if #features > 0 then features = t_concat(features, "<").."<"; else features = ""; end

	if #extensions > 0 then extensions = t_concat(extensions, "<"):gsub("%z", "<").."<"; else extensions = ""; end

	local S = identities..features..extensions;

	local ver = base64(sha1(S));

	return ver, S;

end

return _M;