Method allow_header

boost-http/http.cpp:40–44

 private:
  enum class WriteType { Headers, Chunk, Final };
  static bool allow_header(std::string name) {
    std::transform(name.begin(), name.end(), name.begin(), [](unsigned char c) { return std::tolower(c); });

    return !(name == "host" || name == "connection" || name == "transfer-encoding" || name == "content-length");
  }

  void read_next_request() {
    req_ = {};