Find all (?) Belkin Wemo Devices on LAN and Query API Description

upnp_disco.lua

local socket = require "socket"
local http = require "socket.http"
local ltn12 = require "ltn12"
--[[
local log = require "log"
local xml2lua = require "xml2lua"
local xml_handler = require "xmlhandler.tree"
--]]

-- find element of nested tables, returns nil if any part of the path can't be resolved
local function tablefind(t, path)
  local pathelements = string.gmatch(path, "([^.]+)%.?")
  local item = t

  for element in pathelements do
    if type(item) ~= "table" then item = nil; break end

    item = item[element]
  end

  return item
end

-- record devices when found, so we only query once
local found_devices_by_ip = {}

local function callback(device)
  print("found:", device.ip, "\n", device.id, "\n", device.raw.st)

  if found_devices_by_ip[device.ip] then
    print("already found another way, not querying again")
  else
    found_devices_by_ip[device.ip] = true
    print("new device, querying:", device.raw.location)

    -- Read details
    -- Wemo responds with chunked encoding, must use ltn12 sink
    local responsechunks = {}
    local body,status,headers = http.request{
      url = device.raw.location,
      sink = ltn12.sink.table(responsechunks)
    }

    print(table.concat(responsechunks))
  end
end

local looking_for_all = setmetatable({}, {__index = function() return true end})

local function Set(list)
  local set = {}
  for _,v in pairs(list) do set[v] = true end
  return set
end

local function process_response(val)
  local info = {}
  val = string.gsub(val, "HTTP/1.1 200 OK\r\n", "", 1)
  for k, v in string.gmatch(val, "([%g]+): ([%g ]*)\r\n") do
    info[string.lower(k)] = v
  end
  return info
end

print("starting disco")

local searchterms = {
  --[[
  "urn:schemas-upnp-org:device:basic:1",
  "urn:samsung.com:device:RemoteControlReceiver:1",
  "urn:schemas-upnp-org:device:MediaRenderer:1",
  --]]
  "urn:Belkin:device:sensor:1",
  "urn:Belkin:device:lightswitch:1",
  "urn:Belkin:device:insight:1",
  "urn:Belkin:device:controllee:1",
  "urn:Belkin:device:**",
  "urn:Belkin:device:*",
  "urn:Belkin:device",
  --[[
  "urn:belkin:device:sensor:1",
  "urn:belkin:device:lightswitch:1",
  "urn:belkin:device:insight:1",
  "urn:belkin:device:controllee:1",
  "urn:belkin:device:**",
  "ssdp:all",
  --]]
}

for _,st in ipairs(searchterms) do
  print("searching for:", st)

  local looking_for = {}
  local number_looking_for
  local number_found = 0
  if bulb_ids ~= nil then
    number_looking_for = #bulb_ids
    for _, id in ipairs(bulb_ids) do looking_for[id] = true end
  else
    looking_for = looking_for_all
    number_looking_for = math.maxinteger
  end

  local s = socket.udp()
  assert(s)
  local listen_ip = interface or "0.0.0.0"
  local listen_port = 0

  local multicast_ip = "239.255.255.250"
  local multicast_port = 1900
  local multicast_msg = table.concat(
    {
      'M-SEARCH * HTTP/1.1',
      'HOST: 239.255.255.250:1900',
      'MAN: "ssdp:discover"', -- yes, there are really supposed to be quotes in this one
      'MX: 2',
      'ST: uuid:Insight-1_0-231707K1201DE2::urn:Belkin:device:insight:1',
      '\r\n'
    },
    "\r\n"
  )

  -- Create bind local ip and port
  -- Yeelight will unicast back to this ip and port
  assert(s:setsockname(listen_ip, listen_port))
  local timeouttime = socket.gettime() + 4

  local ids_found = {} -- used to filter duplicates

  print("sending:\n", multicast_msg)
  assert(s:sendto(multicast_msg, multicast_ip, multicast_port))
  while number_found < number_looking_for do
    local time_remaining = math.max(0, timeouttime-socket.gettime())
    s:settimeout(time_remaining)
    local val, rip, rport = s:receivefrom()
    if val then
      --print(val)
      local headers = process_response(val)
      local ip, port = headers["location"]:match("http://([^,/]+):([^,]+)")
      local location = headers["location"]
      local id = headers["usn"]
      local supported_commands = {}
      if headers["support"] then
        string.gsub(headers["support"], "([^ ]*) ?", function(match) table.insert(supported_commands, match) end)
      end

      if rip ~= ip then
        print("recieved discovery response with reported & source IP mismatch, ignoring")
        print(rip, "!=", ip)
      elseif ip and port and id and looking_for[id] and not ids_found[id] then
        ids_found[id] = true
        number_found = number_found + 1
        callback({id = id, ip = ip, port = port, raw = headers})
      end
    elseif rip == "timeout" then
      break
    else
      error(string.format("error receving discovery replies: %s", rip))
    end
  end
  print(string.format("finished, %s found", number_found))
end

print("all finished")