--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/net/websocket/frames.lua Thu Dec 25 10:48:06 2014 +0000
@@ -0,0 +1,195 @@
+-- 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 softreq = require "util.dependencies".softreq;
+local log = require "util.logger".init "websocket.frames";
+local random_bytes = require "util.random".bytes;
+
+local bit;
+pcall(function() bit = require"bit"; end);
+bit = bit or softreq"bit32"
+if not bit then log("error", "No bit module found. Either LuaJIT 2, lua-bitop or Lua 5.2 is required"); end
+local band = bit.band;
+local bor = bit.bor;
+local bxor = bit.bxor;
+local lshift = bit.lshift;
+local rshift = bit.rshift;
+
+local t_concat = table.concat;
+local s_byte = string.byte;
+local s_char= string.char;
+local s_sub = string.sub;
+
+local function read_uint16be(str, pos)
+ local l1, l2 = s_byte(str, pos, pos+1);
+ return l1*256 + l2;
+end
+-- FIXME: this may lose precision
+local function read_uint64be(str, pos)
+ local l1, l2, l3, l4, l5, l6, l7, l8 = s_byte(str, pos, pos+7);
+ return lshift(l1, 56) + lshift(l2, 48) + lshift(l3, 40) + lshift(l4, 32)
+ + lshift(l5, 24) + lshift(l6, 16) + lshift(l7, 8) + l8;
+end
+local function pack_uint16be(x)
+ return s_char(rshift(x, 8), band(x, 0xFF));
+end
+local function get_byte(x, n)
+ return band(rshift(x, n), 0xFF);
+end
+local function pack_uint64be(x)
+ return s_char(rshift(x, 56), get_byte(x, 48), get_byte(x, 40), get_byte(x, 32),
+ get_byte(x, 24), get_byte(x, 16), get_byte(x, 8), band(x, 0xFF));
+end
+
+local function parse_frame_header(frame)
+ if #frame < 2 then return; end
+
+ local byte1, byte2 = s_byte(frame, 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 < 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 = { s_byte(frame, 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)
+ from = from or 1
+ if from < 0 then from = #str + from + 1 end -- negative indicies
+ to = to or #str
+ if to < 0 then to = #str + to + 1 end -- negative indicies
+ local key_len = #key
+ local counter = 0;
+ local data = {};
+ for i = from, to do
+ local key_index = counter%key_len + 1;
+ counter = counter + 1;
+ data[counter] = s_char(bxor(key[key_index], s_byte(str, i)));
+ end
+ return t_concat(data);
+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 < (pos + result.length) then return; 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
+ local key_a = desc.key
+ if key_a then
+ key = s_char(unpack(key_a, 1, 4));
+ else
+ key = random_bytes(4);
+ key_a = {key:byte(1,4)};
+ end
+ b2 = bor(b2, 0x80);
+ data = apply_mask(data, key_a);
+ 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 = s_sub(data, 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;
+};