mineqtt/mqtt.lua

174 lines
3.0 KiB
Lua

local net = require("internet")
local read_varint = function (conn, first_byte)
local b
if first_byte == nil then
b = conn:read(1)
else
b = first_byte
end
local n, s = 0, 0
while b ~= nil and b & 0x80 == 0x80 do
if s > 21 then
return 0, "number too large"
end
n = n + ((b & 0x7F) << s)
s = s + 7
b = conn:read(1)
end
if b == nil then
return n, "eof"
end
return n + (b << s), nil
end
local MqttClient
function open (address, port)
local conn = net.open(address, port)
if conn == nil then
return nil, "connection failed"
end
return MqttClient:new(conn), nil
end
function MqttClient:new (conn)
local c = c or {}
setmetatable(c, self)
self.__index = self
conn.read_varint = read_varint
c.conn = conn
c.is_connecting = false
c.is_connected = false
return c
end
function MqttClient:handle ()
local data = self.conn:read(2)
if data == nil then
return "eof"
end
local ptype, length, _ = string.unpack("B B", s)
local length, err = self.conn:read_varint(length)
if err ~= nil then
return err
end
if length > 0 then
data = self.conn:read(length)
if data == nil then
return "eof"
end
else
data = ""
end
if ptype & 0xF0 == 0x20 then -- CONNACK
if ptype ~= 0x20 or length < 2 then
self:disconnect(0x81)
return "malformed packet"
end
local flags, reason, _ = string.unpack("B B", data)
if flags ~= 0 then
self:disconnect(0x81)
return "malformed packet"
end
if reason > 127 then
self.is_connecting = false
self.is_connected = false
self.conn:close()
self.conn = nil
return "connection closed by server"
elseif reason ~= 0 then
self:disconnect(0x81)
return "malformed packet"
end
self.is_connecting = false
self.is_connected = true
elseif ptype == 0x40 then -- PUBACK
-- TODO
elseif ptype == 0xD0 then -- PINGRESP
-- TODO
elseif ptype == 0xE0 then -- DISCONNECT
-- TODO
end
return nil
end
function MqttClient:connect (username, password)
if self.is_connecting or self.is_connected then
return nil
end
local length = 15
local flags = 1
if username ~= nil then
length = length + 2 + #username
flags = flags | 0x80
end
if password ~= nil then
length = length + 2 + #password
flags = flags | 0x40
end
if length > 127 then
return "packet size exceeds current implementation capabilities"
end
local data = string.pack("> B B s2 B B I2 B s2", 0x10, length, "MQTT", 5, flags, 0, 0, "")
if username ~= nil then
data = data .. string.pack("> s2", username)
end
if password ~= nil then
data = data .. string.pack("> s2", password)
end
local _, err = self.conn:write(data)
if err ~= nil then
return err
end
self.is_connecting = true
return nil
end
function MqttClient:disconnect (reason)
if not (self.is_connecting or self.is_connected) then
return nil
end
if reason == nil then
reason = 0
end
local data = string.pack("> B B B", 0xE0, 1, reason)
local _, err = self.conn:write(data)
if err ~= nil then
return err
end
self.is_connecting = false
self.is_connected = false
self.conn:close()
self.conn = nil
return nil
end