提问者:小点点

错误:分块编码中的十六进制序列非法或缺失


我正在编写自己的超文本传输协议服务器,现在我正在尝试tmplement分块传输编码。我的尝试如下所示:

void HttpServer::SendRespons(HttpServer::Connection &socket_) noexcept {
  int sent = 0;
  int counter = 0;
  int index = 0;
  std::size_t response_size_;
  std::ifstream t(this->conf_.GetRootPath() + socket_.data);
  socket_.respons = {(std::istreambuf_iterator<char>(t)),
                     std::istreambuf_iterator<char>()};
  t.clear();
  response_size_ = socket_.respons.size();
  std::vector<std::string> strVec;
  strVec.reserve(socket_.respons.size() / BUFSIZE + 2);
  strVec.push_back(
      "HTTP/1.1 200 OK\r\nServer: http\r\nContent-Type: "
      "text/html\r\nTransfer-Encoding: "
      "chunked\r\nConnection: Keep-Alive\r\n\r\n");
  while (index + 16374 < static_cast<int>(response_size_)) {
    strVec.push_back("3ff6\r\n" + socket_.respons.substr(index, 16374) +
                     "\r\n\r\n");
    index += 16374;
  }
  std::stringstream stream;
  stream << std::hex
         << std::atoi(std::to_string(response_size_ - index).c_str());
  strVec.push_back(stream.str() + "\r\n" +
                   socket_.respons.substr(index, response_size_ - index) +
                   "\r\n\r\n");
  strVec.push_back("0\r\n\r\n");
  index = 0;
  response_size_ += (strVec[0].size() + strVec[strVec.size() - 1].size());

  std::lock_guard<std::mutex> lg(this->connected_clients_mux_);
  while (index < static_cast<int>(strVec.size())) {
    int len =
        write(socket_.socket, (char *)&strVec[index][0], strVec[index].size());

    if (len < 0) {
      //...
      } else if ((errno == EPIPE) || (errno == ECONNRESET)) {
        std::cout << __FILE__ << " " << __func__
                  << " sent stop (epipe || econreset), len= " << len << " "
                  << "error #" << errno << std::endl;
        break;
      //...
    }
    ++index;
    sent += len;
    std::cout << __FILE__ << " " << __func__ << " sent " << len << " "
              << "packet #" << ++counter << std::endl;
  }
  std::cout << std::endl
            << __FILE__ << " " << __func__
            << " assumed length:" << response_size_
            << " sent:" << sent << " to: " << socket_.socket << std::endl;
}

上面的函数应该读取文件,将其分成几部分并逐个传递。据我所知,拆分进行得很好,但是在尝试发送文件时:

curl -v http://localhost:8080/filename

我得到:

*   Trying 127.0.0.1:8080...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 8080 (#0)
> GET /filename HTTP/1.1
> Host: localhost:8080
> User-Agent: curl/7.68.0
> Accept: */*
> 
* Mark bundle as not supporting multiuse
< HTTP/1.1 200 OK
< Server: http
< Content-Type: text/html
< Transfer-Encoding: chunked
< Connection: Keep-Alive
< 
//.... here is first chunk
* Illegal or missing hexadecimal sequence in chunked-encoding
* Closing connection 0
curl: (56) Illegal or missing hexadecimal sequence in chunked-encoding

如您所见,客户端接收响应的第一部分(标头)并处理它们。之后-它期望消息的正文。收到第一部分后,连接关闭。我知道错误是以我自己的块格式写在消息中的某个地方,但我自己无法确定确切位置。我遵循了https://en.wikipedia.org/wiki/Chunked_transfer_encoding#Format的指示,但obv犯了一个错误。由于客户端没有为它期望的十六进制序列输出任何内容,因此它接收并认为错误的十六进制序列没有任何内容。我请求帮助。


共1个答案

匿名用户

我认为在这部分代码的末尾只需要一个\r\n

    strVec.push_back("3ff6\r\n" + socket_.respons.substr(index, 16374) +
                     "\r\n\r\n");

您不应该在前一个块和下一个块的十六进制大小之间插入空行。(最后一个块也是如此)

您提供的维基百科页面在示例中的块之间插入空行只是为了增加易读性,但这些空行实际上并未发送。