File

net/websocket/frames.lua @ 12525:8087f5357f53 0.12

mod_smacks: Fix bounce of stanzas directed to full JID on unclean disconnect Fixes #1758 Introduced in 1ea01660c79a In e62025f949f9 to and from was inverted since it changed from acting on a reply to acting on the original stanza (or a clone thereof) Unsure of the purpose of this check, you don't usually send stanzas to your own full JID. Perhaps guarding against routing loops? The check was present in the original commit of mod_smacks, prosody-modules rev 9a7671720dec
author Kim Alvefur <zash@zash.se>
date Fri, 27 May 2022 12:05:47 +0200
parent 12386:2d3080d02960
child 12974:ba409c67353b
line wrap: on
line source

-- Prosody IM
-- Copyright (C) 2012 Florian Zeitz
-- Copyright (C) 2014 Daurnimator
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--

local random_bytes = require "util.random".bytes;

local bit = require "util.bitcompat";
local band = bit.band;
local bor = bit.bor;
local sbit = require "util.strbitop";
local sxor = sbit.sxor;

local s_char = string.char;
local s_pack = require"util.struct".pack;
local s_unpack = require"util.struct".unpack;

local function pack_uint16be(x)
	return s_pack(">I2", x);
end
local function pack_uint64be(x)
	return s_pack(">I8", x);
end

local function read_uint16be(str, pos)
	if type(str) ~= "string" then
		str, pos = str:sub(pos, pos+1), 1;
	end
	return s_unpack(">I2", str, pos);
end
local function read_uint64be(str, pos)
	if type(str) ~= "string" then
		str, pos = str:sub(pos, pos+7), 1;
	end
	return s_unpack(">I8", str, pos);
end

local function parse_frame_header(frame)
	if frame:len() < 2 then return; end

	local byte1, byte2 = frame:byte(1, 2);
	local result = {
		FIN = band(byte1, 0x80) > 0;
		RSV1 = band(byte1, 0x40) > 0;
		RSV2 = band(byte1, 0x20) > 0;
		RSV3 = band(byte1, 0x10) > 0;
		opcode = band(byte1, 0x0F);

		MASK = band(byte2, 0x80) > 0;
		length = band(byte2, 0x7F);
	};

	local length_bytes = 0;
	if result.length == 126 then
		length_bytes = 2;
	elseif result.length == 127 then
		length_bytes = 8;
	end

	local header_length = 2 + length_bytes + (result.MASK and 4 or 0);
	if frame:len() < header_length then return; end

	if length_bytes == 2 then
		result.length = read_uint16be(frame, 3);
	elseif length_bytes == 8 then
		result.length = read_uint64be(frame, 3);
	end

	if result.MASK then
		result.key = frame:sub(length_bytes+3, length_bytes+6);
	end

	return result, header_length;
end

-- XORs the string `str` with the array of bytes `key`
-- TODO: optimize
local function apply_mask(str, key, from, to)
	return sxor(str:sub(from or 1, to or -1), key);
end

local function parse_frame_body(frame, header, pos)
	if header.MASK then
		return apply_mask(frame, header.key, pos, pos + header.length - 1);
	else
		return frame:sub(pos, pos + header.length - 1);
	end
end

local function parse_frame(frame)
	local result, pos = parse_frame_header(frame);
	if result == nil or frame:len() < (pos + result.length) then return nil, nil, result; end
	result.data = parse_frame_body(frame, result, pos+1);
	return result, pos + result.length;
end

local function build_frame(desc)
	local data = desc.data or "";

	assert(desc.opcode and desc.opcode >= 0 and desc.opcode <= 0xF, "Invalid WebSocket opcode");
	if desc.opcode >= 0x8 then
		-- RFC 6455 5.5
		assert(#data <= 125, "WebSocket control frames MUST have a payload length of 125 bytes or less.");
	end

	local b1 = bor(desc.opcode,
		desc.FIN and 0x80 or 0,
		desc.RSV1 and 0x40 or 0,
		desc.RSV2 and 0x20 or 0,
		desc.RSV3 and 0x10 or 0);

	local b2 = #data;
	local length_extra;
	if b2 <= 125 then -- 7-bit length
		length_extra = "";
	elseif b2 <= 0xFFFF then -- 2-byte length
		b2 = 126;
		length_extra = pack_uint16be(#data);
	else -- 8-byte length
		b2 = 127;
		length_extra = pack_uint64be(#data);
	end

	local key = ""
	if desc.MASK then
		key = desc.key
		if not key then
			key = random_bytes(4);
		end
		b2 = bor(b2, 0x80);
		data = apply_mask(data, key);
	end

	return s_char(b1, b2) .. length_extra .. key .. data
end

local function parse_close(data)
	local code, message
	if #data >= 2 then
		code = read_uint16be(data, 1);
		if #data > 2 then
			message = data:sub(3);
		end
	end
	return code, message
end

local function build_close(code, message, mask)
	local data = pack_uint16be(code);
	if message then
		assert(#message<=123, "Close reason must be <=123 bytes");
		data = data .. message;
	end
	return build_frame({
		opcode = 0x8;
		FIN = true;
		MASK = mask;
		data = data;
	});
end

return {
	parse_header = parse_frame_header;
	parse_body = parse_frame_body;
	parse = parse_frame;
	build = build_frame;
	parse_close = parse_close;
	build_close = build_close;
};