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mod_pubsub_mqtt/mqtt.lib.lua @ 3412:d50d1dfab9eb
mod_pubsub_text_interface/README: Add a Compatibility section
author | Kim Alvefur <zash@zash.se> |
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date | Sat, 22 Dec 2018 18:52:13 +0100 |
parent | 1343:7dbde05b48a9 |
child | 5114:d2a84e6aed2b |
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local bit = require "bit"; local stream_mt = {}; stream_mt.__index = stream_mt; function stream_mt:read_bytes(n_bytes) module:log("debug", "Reading %d bytes... (buffer: %d)", n_bytes, #self.buffer); local data = self.buffer; if not data then module:log("debug", "No data, pausing."); data = coroutine.yield(); module:log("debug", "Have %d bytes of data now (want %d)", #data, n_bytes); end if #data >= n_bytes then data, self.buffer = data:sub(1, n_bytes), data:sub(n_bytes+1); elseif #data < n_bytes then module:log("debug", "Not enough data (only %d bytes out of %d), pausing.", #data, n_bytes); self.buffer = data..coroutine.yield(); module:log("debug", "Now we have %d bytes, reading...", #data); return self:read_bytes(n_bytes); end module:log("debug", "Returning %d bytes (buffer: %d)", #data, #self.buffer); return data; end function stream_mt:read_string() local len1, len2 = self:read_bytes(2):byte(1,2); local len = bit.lshift(len1, 8) + len2; return self:read_bytes(len), len+2; end local packet_type_codes = { "connect", "connack", "publish", "puback", "pubrec", "pubrel", "pubcomp", "subscribe", "subak", "unsubscribe", "unsuback", "pingreq", "pingresp", "disconnect" }; function stream_mt:read_packet() local packet = {}; local header = self:read_bytes(1):byte(); packet.type = packet_type_codes[bit.rshift(bit.band(header, 0xf0), 4)]; packet.dup = bit.band(header, 0x08) == 0x08; packet.qos = bit.rshift(bit.band(header, 0x06), 1); packet.retain = bit.band(header, 0x01) == 0x01; -- Get length local length, multiplier = 0, 1; repeat local digit = self:read_bytes(1):byte(); length = length + bit.band(digit, 0x7f)*multiplier; multiplier = multiplier*128; until bit.band(digit, 0x80) == 0; packet.length = length; if packet.type == "connect" then if self:read_string() ~= "MQIsdp" then module:log("warn", "Unexpected packet signature!"); packet.type = nil; -- Invalid packet else packet.version = self:read_bytes(1):byte(); packet.connect_flags = self:read_bytes(1):byte(); packet.keepalive_timer = self:read_bytes(1):byte(); length = length - 11; end elseif packet.type == "publish" then packet.topic = self:read_string(); length = length - (#packet.topic+2); if packet.qos == 1 or packet.qos == 2 then packet.id = self:read_bytes(2); length = length - 2; end elseif packet.type == "subscribe" then if packet.qos == 1 or packet.qos == 2 then packet.id = self:read_bytes(2); length = length - 2; end local topics = {}; while length > 0 do local topic, len = self:read_string(); table.insert(topics, topic); self:read_bytes(1); -- QoS not used length = length - (len+1); end packet.topics = topics; end if length > 0 then packet.data = self:read_bytes(length); end return packet; end local function new_parser(self) return coroutine.wrap(function (data) self.buffer = data; while true do data = coroutine.yield(self:read_packet()); module:log("debug", "Parser: %d new bytes", #data); self.buffer = (self.buffer or "")..data; end end); end function stream_mt:feed(data) module:log("debug", "Feeding %d bytes", #data); local packets = {}; local packet = self.parser(data); while packet do module:log("debug", "Received packet"); table.insert(packets, packet); packet = self.parser(""); end module:log("debug", "Returning %d packets", #packets); return packets; end local function new_stream() local stream = setmetatable({}, stream_mt); stream.parser = new_parser(stream); return stream; end local function serialize_packet(packet) local type_num = 0; for i, v in ipairs(packet_type_codes) do -- FIXME: I'm so tired right now. if v == packet.type then type_num = i; break; end end local header = string.char(bit.lshift(type_num, 4)); if packet.type == "publish" then local topic = packet.topic or ""; packet.data = string.char(bit.band(#topic, 0xff00), bit.band(#topic, 0x00ff))..topic..packet.data; elseif packet.type == "suback" then local t = {}; for _, topic in ipairs(packet.topics) do table.insert(t, string.char(bit.band(#topic, 0xff00), bit.band(#topic, 0x00ff))..topic.."\000"); end packet.data = table.concat(t); end -- Get length local length = #(packet.data or ""); repeat local digit = length%128; length = math.floor(length/128); if length > 0 then digit = bit.bor(digit, 0x80); end header = header..string.char(digit); -- FIXME: ... until length <= 0; return header..(packet.data or ""); end return { new_stream = new_stream; serialize_packet = serialize_packet; };