Websocket read

websocket.nim

proc read(ws: TWebSocketServer, client: TWebSocket): string =
  var buffer = cstring(ws.buffer)
  var read   = client.socket.recv(buffer, 2)
  var length = int(uint8(buffer[1]) and 127)
  
  template readLength(size: int) =
    ## Read next `size` bytes to determine length
    read   = client.socket.recv(buffer, size, 0)
    length = 0 #Reset the length to 0

    let max = size * 8
    for i in 1 .. size:
      length += int(buffer[i - 1]) shl (max - (i * 8))

  if   length == 126: readLength(2)
  elif length == 127: readLength(8)

  #Read the rest of the data being transmitted
  read   = client.socket.recv(buffer, length + 4, 0)
  result = newString(length)

  #Decode the buffer & copy into result
  var j = 0
  for i in 0 .. length-1:
    result[j] = char(uint8(buffer[i + 4]) xor uint8(buffer[j mod 4]))
    inc(j)