WIP-QsysWebsockets.lua

S = TcpSocket.New();
S.EventHandler = print;
S:Connect(<HOST>, 80);
S.ReconnectTimeout = 0;

function randomWebSocketKey()
  return Crypto.Base64Encode(('x'):rep(16):gsub('.', function() return string.char(math.random(0,255)) end));
end;

S.Connected = function()
  Mode = 'HTTP';
  print('CONNECTED');
  S:Write(table.concat({
    'GET / HTTP/1.1',
    'Host: <HOST>',
    'Connection: Upgrade',
    'Upgrade: websocket',
    'Sec-WebSocket-Version: 13',
    'Sec-WebSocket-Key: ' .. randomWebSocketKey()
  }, '\r\n').. '\r\n\r\n');
end;

function send(data)
  print('> ' .. data);
  local len, epl = #data, '';
  if len > 125 and len <= 0xffff then epl = bitstring.pack('16:int', len); len = 126; 
  elseif len > 125 and len < 2^53 then epl = bitstring.pack('64:int', len); len = 127; end
  local frame = bitstring.pack('1:int, 3:int, 4:int 1:int 7:int', 1, 0, 1, 1, len) .. epl .. '\0\0\0\0' .. data;
  S:Write(frame); 
end;
 
Mode = 'HTTP';
S.Data = function(sock)

  if(Mode == 'HTTP') then
    for http in function() return sock:ReadLine(TcpSocket.EOL.Custom, '\r\n\r\n'); end do
      local code = http:match('^[^ ]+ (%d+)');
      if(code == '101') then
        Mode = 'WS-INIT';
        send(<ON-CONNECT MESSAGE>);
      end;
    end;
  end;
  
  while(true) do
    if(Mode == 'WS-INIT') then
      if(sock.BufferLength < 2) then return; end;
      local fin, rsv, opcode, mask, len = bitstring.unpack('1:int 3:int 4:int 1:int 7:int', sock:Read(2));
      local sbuf = Packet and Packet.fin and Packet.buf or nil;
      Packet = { fin=fin, rsv=rsv, opcode=opcode, mask=mask, len=len };
      if(len > 125) then Mode = 'WS-EPL'; 
      else Mode = 'WS-PAYLOAD'; end; 
    end;
     
    if(Mode == 'WS-EPL') then
      if(Packet.len == 126) then
        if(sock.BufferLength < 2) then return; end;
        Packet.len = bitstring.unpack('16:int', sock:Read(2));
        Mode = 'WS-PAYLOAD';
      elseif(Packet.len == 127) then
        if(sock.BufferLength < 8) then return; end;
        Packet.len = bitstring.unpack('64:int', sock:Read(8));
      end;
    end;
    
    if(Mode == 'WS-PAYLOAD') then
      if(sock.BufferLength < Packet.len) then return; end;
      Mode = 'WS-INIT'; -- reset for handling of next frame
      Buf = (Buf or '') .. sock:Read(Packet.len);
      if(Packet.fin == 1) then
        local msg = Buf; Buf = nil;
        print('< ' .. msg);
        local ok, data = pcall(json.decode, msg);
        if(ok and data) then
            -- handle message
        end;
      end;
    end;

  end;

end;