-- 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 configmanager = require "core.configmanager";
local log = require "util.logger".init("certmanager");
local ssl = ssl;
local ssl_newcontext = ssl and ssl.newcontext;

local tostring = tostring;
local pairs = pairs;
local type = type;
local io_open = io.open;
local t_concat = table.concat;

local prosody = prosody;
local resolve_path = configmanager.resolve_relative_path;
local config_path = prosody.paths.config;

local luasec_has_noticket, luasec_has_verifyext, luasec_has_no_compression;
if ssl then
	local luasec_major, luasec_minor = ssl._VERSION:match("^(%d+)%.(%d+)");
	luasec_has_noticket = tonumber(luasec_major)>0 or tonumber(luasec_minor)>=4;
	luasec_has_verifyext = tonumber(luasec_major)>0 or tonumber(luasec_minor)>=5;
	luasec_has_no_compression = tonumber(luasec_major)>0 or tonumber(luasec_minor)>=5;
end

module "certmanager"

-- Global SSL options if not overridden per-host
local global_ssl_config = configmanager.get("*", "ssl");

-- Built-in defaults
local core_defaults = {
	capath = "/etc/ssl/certs";
	protocol = "tlsv1+";
	verify = (ssl and ssl.x509 and { "peer", "client_once", }) or "none";
	options = {
		cipher_server_preference = true;
		no_ticket = luasec_has_noticket;
		no_compression = luasec_has_no_compression and configmanager.get("*", "ssl_compression") ~= true;
		-- Has no_compression? Then it has these too...
		single_dh_use = luasec_has_no_compression;
		single_ecdh_use = luasec_has_no_compression;
	};
	verifyext = { "lsec_continue", "lsec_ignore_purpose" };
	curve = "secp384r1";
	ciphers = "HIGH+kEDH:HIGH+kEECDH:HIGH:!PSK:!SRP:!3DES:!aNULL";
}
local path_options = { -- These we pass through resolve_path()
	key = true, certificate = true, cafile = true, capath = true, dhparam = true
}
local set_options = {
	options = true, verify = true, verifyext = true
}

if ssl and not luasec_has_verifyext and ssl.x509 then
	-- COMPAT mw/luasec-hg
	for i=1,#core_defaults.verifyext do -- Remove lsec_ prefix
		core_defaults.verify[#core_defaults.verify+1] = core_defaults.verifyext[i]:sub(6);
	end
end

local function merge_set(t, o)
	if type(t) ~= "table" then t = { t } end
	for k,v in pairs(t) do
		if v == true or v == false then
			o[k] = v;
		else
			o[v] = true;
		end
	end
	return o;
end

local protocols = { "sslv2", "sslv3", "tlsv1", "tlsv1_1", "tlsv1_2" };
for i = 1, #protocols do protocols[protocols[i] .. "+"] = i - 1; end

function create_context(host, mode, user_ssl_config)
	user_ssl_config = user_ssl_config or {}
	user_ssl_config.mode = mode;

	if not ssl then return nil, "LuaSec (required for encryption) was not found"; end

	if global_ssl_config then
		for option,default_value in pairs(global_ssl_config) do
			if user_ssl_config[option] == nil then
				user_ssl_config[option] = default_value;
			end
		end
	end

	for option,default_value in pairs(core_defaults) do
		if user_ssl_config[option] == nil then
			user_ssl_config[option] = default_value;
		end
	end

	local min_protocol = protocols[user_ssl_config.protocol];
	if min_protocol then
		user_ssl_config.protocol = "sslv23";
		for i = min_protocol, 1, -1 do
			user_ssl_config.options["no_"..protocols[i]] = true;
		end
	end

	for option in pairs(set_options) do
		local merged = {};
		merge_set(core_defaults[option], merged);
		merge_set(global_ssl_config[option], merged);
		merge_set(user_ssl_config[option], merged);
		local final_array = {};
		for opt, enable in pairs(merged) do
			if enable then
				final_array[#final_array+1] = opt;
			end
		end
		user_ssl_config[option] = final_array;
	end

	-- We can't read the password interactively when daemonized
	user_ssl_config.password = user_ssl_config.password or
		function() log("error", "Encrypted certificate for %s requires 'ssl' 'password' to be set in config", host); end;

	for option in pairs(path_options) do
		if type(user_ssl_config[option]) == "string" then
			user_ssl_config[option] = resolve_path(config_path, user_ssl_config[option]);
		end
	end

	-- Allow the cipher list to be a table
	if type(user_ssl_config.ciphers) == "table" then
		user_ssl_config.ciphers = t_concat(user_ssl_config.ciphers, ":")
	end

	if mode == "server" then
		if not user_ssl_config.key then return nil, "No key present in SSL/TLS configuration for "..host; end
		if not user_ssl_config.certificate then return nil, "No certificate present in SSL/TLS configuration for "..host; end
	end

	-- LuaSec expects dhparam to be a callback that takes two arguments.
	-- We ignore those because it is mostly used for having a separate
	-- set of params for EXPORT ciphers, which we don't have by default.
	if type(user_ssl_config.dhparam) == "string" then
		local f, err = io_open(user_ssl_config.dhparam);
		if not f then return nil, "Could not open DH parameters: "..err end
		local dhparam = f:read("*a");
		f:close();
		user_ssl_config.dhparam = function() return dhparam; end
	end

	local ctx, err = ssl_newcontext(user_ssl_config);

	-- COMPAT Older LuaSec ignores the cipher list from the config, so we have to take care
	-- of it ourselves (W/A for #x)
	if ctx and user_ssl_config.ciphers then
		local success;
		success, err = ssl.context.setcipher(ctx, user_ssl_config.ciphers);
		if not success then ctx = nil; end
	end

	if not ctx then
		err = err or "invalid ssl config"
		local file = err:match("^error loading (.-) %(");
		if file then
			if file == "private key" then
				file = user_ssl_config.key or "your private key";
			elseif file == "certificate" then
				file = user_ssl_config.certificate or "your certificate file";
			end
			local reason = err:match("%((.+)%)$") or "some reason";
			if reason == "Permission denied" then
				reason = "Check that the permissions allow Prosody to read this file.";
			elseif reason == "No such file or directory" then
				reason = "Check that the path is correct, and the file exists.";
			elseif reason == "system lib" then
				reason = "Previous error (see logs), or other system error.";
			elseif reason == "(null)" or not reason then
				reason = "Check that the file exists and the permissions are correct";
			else
				reason = "Reason: "..tostring(reason):lower();
			end
			log("error", "SSL/TLS: Failed to load '%s': %s (for %s)", file, reason, host);
		else
			log("error", "SSL/TLS: Error initialising for %s: %s", host, err);
		end
	end
	return ctx, err;
end

function reload_ssl_config()
	global_ssl_config = configmanager.get("*", "ssl");
end

prosody.events.add_handler("config-reloaded", reload_ssl_config);

return _M;