gRPC request how to get request body in envoyfilter about istio HOT 3 OPEN

function envoy_on_request(handle)
  local headers = {}
  for k, v in pairs(handle:headers()) do
    headers[k] = v
  end
  handle:streamInfo():dynamicMetadata():set(
    "envoy.lua.log", "request_headers", headers)

  local md = handle:headers():get(":method")
  if md ~= "POST" and md ~= "PUT" then return end

  local n = 0
  local body = ""
  for chunk in handle:bodyChunks() do
    body = body..chunk:getBytes(0, chunk:length())
    n = n + chunk:length()
    if n > 10240 then break end
  end

  if n > 0 then
    if handle:headers():get("content-type") == "application/grpc" then
      handle:streamInfo():dynamicMetadata():set(
        "envoy.lua.log", "request_body", handle:base64Escape(body))
    else
      handle:streamInfo():dynamicMetadata():set(
        "envoy.lua.log", "request_body", body)
    end
  end

end