309 lines
6.6 KiB
Lua
309 lines
6.6 KiB
Lua
local computer = require("computer")
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local mqtt = {}
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local safeRead = function (conn, n)
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local success, result, err = pcall(conn.read, conn, n)
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if success then
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return result, err
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end
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return nil, result
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end
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local readVarint = function (conn, first_byte)
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local b, data, err
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if first_byte == nil then
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data, err = safeRead(conn, 1)
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if err ~= nil then
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return nil, err
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end
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b = string.byte(data)
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else
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b = first_byte
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end
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local n, s = 0, 0
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while b & 0x80 == 0x80 do
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if s > 21 then
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return nil, "number too large"
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end
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n = n + ((b & 0x7F) << s)
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s = s + 7
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data, err = safeRead(conn, 1)
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if err ~= nil then
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return nil, err
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end
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b = string.byte(data)
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end
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return n + (b << s), nil
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end
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local encodeVarint = function (n)
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if n > 268435455 then
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return nil, "number too large"
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end
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local data = ""
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while n > 127 do
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data = data .. string.char(0x80 | n & 0x7F)
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n = n >> 7
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end
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return data .. string.char(n), nil
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end
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local MqttClient = {}
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function mqtt.open (address, port)
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local conn, err = require("internet").open(address, port)
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if conn == nil then
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return nil, err
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end
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return MqttClient:new(conn), nil
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end
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function MqttClient:new (conn)
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local c = c or {}
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setmetatable(c, self)
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self.__index = self
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conn.readVarint = readVarint
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conn.safeRead = safeRead
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conn:setTimeout(0)
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c.conn = conn
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c.is_connecting = false
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c.is_connected = false
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return c
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end
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function MqttClient:handle ()
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if not (self.is_connecting or self.is_connected) then
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return "no connection"
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end
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local data, err = self.conn:safeRead(2)
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if err ~= nil then
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if (string.find(err, "timeout")) then
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return nil
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end
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return err
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end
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local ptype, length, _ = string.unpack("B B", data)
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local length, err = self.conn:readVarint(length)
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if err ~= nil then
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return err
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end
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if length > 0 then
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data, err = self.conn:safeRead(length)
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if err ~= nil then
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return err
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end
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else
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data = ""
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end
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if ptype & 0xF0 == 0x20 then -- CONNACK
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if ptype ~= 0x20 or length < 2 then
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self:disconnect(0x81)
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return "malformed packet"
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end
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local flags, reason, _ = string.unpack("B B", data)
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if flags ~= 0 then
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self:disconnect(0x81)
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return "invalid flags"
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end
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if reason > 127 then
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self.is_connecting = false
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self.is_connected = false
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self.conn:close()
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self.conn = nil
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return "connection closed by server"
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elseif reason ~= 0 then
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self:disconnect(0x81)
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return "unrecognized reason"
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end
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self.is_connecting = false
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self.is_connected = true
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elseif ptype & 0xF0 == 0x40 then -- PUBACK
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-- TODO
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elseif ptype & 0xF0 == 0x90 then -- SUBACK
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-- TODO
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elseif ptype & 0xF0 == 0xD0 then -- PINGRESP
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-- TODO
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elseif ptype & 0xF0 == 0x30 then -- PUBLISH
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local topic, _, next = string.unpack("> s2 B", data)
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local message = string.sub(data, next)
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computer.pushSignal("mqtt_message", topic, message)
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elseif ptype & 0xF0 == 0xE0 then -- DISCONNECT
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if ptype ~= 0xE0 then
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self:disconnect(0x81)
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return "malformed packet"
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end
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self.is_connecting = false
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self.is_connected = false
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if length > 0 then
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reason, _ = string.unpack("B", data)
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if reason ~= 0 then
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return "disconnect with error"
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end
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end
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return "disconnect"
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end
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return nil
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end
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function MqttClient:connect (username, password)
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if self.is_connecting or self.is_connected then
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return "already connected"
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end
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local length = 13
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local flags = 2
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if username ~= nil then
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length = length + 2 + #username
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flags = flags | 0x80
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end
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if password ~= nil then
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length = length + 2 + #password
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flags = flags | 0x40
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end
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local data = string.char(0x10) .. encodeVarint(length) .. string.pack("> s2 B B I2 B s2", "MQTT", 5, flags, 0, 0, "")
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if username ~= nil then
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data = data .. string.pack("> s2", username)
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end
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if password ~= nil then
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data = data .. string.pack("> s2", password)
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end
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local _, err = self.conn:write(data)
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if err ~= nil then
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return err
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end
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local _, err = self.conn:flush()
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if err ~= nil then
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return err
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end
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self.is_connecting = true
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return nil
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end
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function MqttClient:publish (topic, payload)
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if not (self.is_connecting or self.is_connected) then
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return "no connection"
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end
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if not topic or #topic == 0 then
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return "topic is required"
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end
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if not payload then
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payload = ""
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end
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local flags = 0
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local length = 3 + #topic + #payload
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local data = string.char(0x30 | flags) .. encodeVarint(length) .. string.pack("> s2 B", topic, 0) .. payload
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local _, err = self.conn:write(data)
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if err ~= nil then
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return err
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end
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local _, err = self.conn:flush()
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if err ~= nil then
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return err
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end
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return nil
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end
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function MqttClient:subscribe (...)
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if not (self.is_connecting or self.is_connected) then
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return "no connection"
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end
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local count = select('#', ...)
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if count == 0 then
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return "topic is required"
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end
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local packet_id = 1
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local data = string.pack("> I2 B", packet_id, 0)
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for i = 1, count do
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data = data .. string.pack("> s2 B", select(i, ...), 0)
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end
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local header = string.char(0x82) .. encodeVarint(#data)
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local _, err = self.conn:write(header .. data)
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if err ~= nil then
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return err
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end
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local _, err = self.conn:flush()
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if err ~= nil then
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return err
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end
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return nil
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end
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function MqttClient:disconnect (reason)
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if not (self.is_connecting or self.is_connected) then
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return "no connection"
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end
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if reason == nil then
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reason = 0
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end
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local data = string.pack("> B B B", 0xE0, 1, reason)
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local _, err = self.conn:write(data)
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if err ~= nil then
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return err
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end
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local _, err = self.conn:flush()
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if err ~= nil then
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return err
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end
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self.is_connecting = false
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self.is_connected = false
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self.conn:close()
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self.conn = nil
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return nil
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end
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return mqtt |