HTTP 服务器的100 Continue处理规范

最新推荐文章于 2024-03-23 23:35:04 发布

原创最新推荐文章于 2024-03-23 23:35:04 发布 · 5.1k 阅读

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#服务器 #server #exception #include #processing #stream

本文详细解析了HTTP/1.1规范中关于100Continue响应的要求，包括服务器如何正确处理带100-continue期望的请求头字段的请求，何时发送及不应发送100Continue响应的情况。

服务器端，对于100 Continue的处理，比较复杂啦，国内又没什么文档，导致写WEB 服务器的脚步非常缓慢。现在觉得，一个好的程序员，除了精通编程语言本身外，还要精通英语。英文原文如下：

Requirements for HTTP/1.1 origin servers:

      - Upon receiving a request which includes an Expect request-header
        field with the "100-continue" expectation, an origin server MUST
        either respond with 100 (Continue) status and continue to read
        from the input stream, or respond with a final status code. The
        origin server MUST NOT wait for the request body before sending
        the 100 (Continue) response. If it responds with a final status
        code, it MAY close the transport connection or it MAY continue

        to read and discard the rest of the request.  It MUST NOT
        perform the requested method if it returns a final status code.

      - An origin server SHOULD NOT send a 100 (Continue) response if
        the request message does not include an Expect request-header
        field with the "100-continue" expectation, and MUST NOT send a
        100 (Continue) response if such a request comes from an HTTP/1.0
        (or earlier) client. There is an exception to this rule: for
        compatibility with RFC 2068, a server MAY send a 100 (Continue)
        status in response to an HTTP/1.1 PUT or POST request that does
        not include an Expect request-header field with the "100-
        continue" expectation. This exception, the purpose of which is
        to minimize any client processing delays associated with an
        undeclared wait for 100 (Continue) status, applies only to
        HTTP/1.1 requests, and not to requests with any other HTTP-
        version value.

      - An origin server MAY omit a 100 (Continue) response if it has
        already received some or all of the request body for the
        corresponding request.

      - An origin server that sends a 100 (Continue) response MUST
        ultimately send a final status code, once the request body is
        received and processed, unless it terminates the transport
        connection prematurely.

      - If an origin server receives a request that does not include an
        Expect request-header field with the "100-continue" expectation,
        the request includes a request body, and the server responds
        with a final status code before reading the entire request body
        from the transport connection, then the server SHOULD NOT close
        the transport connection until it has read the entire request,
        or until the client closes the connection. Otherwise, the client
        might not reliably receive the response message. However, this
        requirement is not be construed as preventing a server from
        defending itself against denial-of-service attacks, or from
        badly broken client implementations.