Python3 ThreadingHTTPServer 无法发送分块编码响应

Question

我正在 Python3 中实现一个简单的反向代理，我需要使用 transfer-encoding chunked 模式发送响应。

我从这个 post but I have some problems when sending the chunks in the format described here

中得到了启发

如果我发送 length <= 9 bytes 的块，客户端会正确接收消息，否则发送 length >= 10 bytes 的块时，好像有些没收到，消息一直卡在客户端无限等待

这是一个非工作代码的例子：

from http.server import BaseHTTPRequestHandler, ThreadingHTTPServer


class ProxyHTTPRequestHandler(BaseHTTPRequestHandler):
    protocol_version = 'HTTP/1.1'
 
    def do_GET(self, body=True):

        # HTTP 200 + minimal HTTP headers in response
        self.send_response(200)
        self.send_header('transfer-encoding', 'chunked')
        self.send_header('Content-Type', 'text/plain')
        self.end_headers()

        # writing 5 chunks of 10 characters
        for i in range(5):
            text = str(i+1) * 10  # concatenate 10 chars
            chunk = '{0:d}\r\n'.format(len(text)) + text + '\r\n'
            self.wfile.write(chunk.encode(encoding='utf-8'))

        # writing close sequence
        close_chunk = '0\r\n\r\n'
        self.wfile.write(close_chunk.encode(encoding='utf-8'))


def main():
    try:
        server_address = ('127.0.0.1', 8099)

        # I use ThreadingHTTPServer but the problem persists also with HTTPServer
        httpd = ThreadingHTTPServer(server_address, ProxyHTTPRequestHandler)
        print('http server is running')
        httpd.serve_forever()
    except KeyboardInterrupt:
        print(" ^C entered, stopping web server...")
        httpd.socket.close()


if __name__ == '__main__':
    main()

在这种情况下，几秒钟后，只有当我手动停止 python 执行时，Postman 中的结果如下。请注意缺少的“2222222222”块

但是如果我改用这个长度：

    # writing the same 5 chunks of 9 characters
    for i in range(5):
        text = str(i+1) * 9  # concatenate 9 chars
        chunk = '{0:d}\r\n'.format(len(text)) + text + '\r\n'
        self.wfile.write(chunk.encode(encoding='utf-8'))

    # writing close sequence
    close_chunk = '0\r\n\r\n'
    self.wfile.write(close_chunk.encode(encoding='utf-8'))

通信正确结束（6ms 后所有 5 个块都被正确解释）

部分版本信息：

HTTP Client: Postman 8.10 

(venv) manuel@MBP ReverseProxy % python -V
Python 3.9.2

(venv) manuel@MBP ReverseProxy % pip freeze
certifi==2021.10.8
charset-normalizer==2.0.6
idna==3.2
requests==2.26.0
urllib3==1.26.7

提前感谢您的任何提示！

Answer 1

我 post 解决方案（感谢来自 bugs.python.org 的 Martin Panter）以防其他人将来遇到同样的问题。

该行为是由块大小部分引起的，必须是十六进制格式，不是十进制.

不幸的是来自 Mozilla docs the format was not specified and the example used only length < 10. A formal definition is found here

总之，工作版本如下（使用 {0:x} 而不是 {0:d}）

# writing the same 5 chunks of 9 characters
    for i in range(5):
        text = str(i+1) * 9  # concatenate 9 chars
        chunk = '{0:x}\r\n'.format(len(text)) + text + '\r\n'
        self.wfile.write(chunk.encode(encoding='utf-8'))

    # writing close sequence
    close_chunk = '0\r\n\r\n'
    self.wfile.write(close_chunk.encode(encoding='utf-8'))

Python3 ThreadingHTTPServer 无法发送分块编码响应

Python3 ThreadingHTTPServer fails to send chunked encoded response

python

http

chunked

httpserver

chunked-encoding