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87 lines
3.2 KiB
HTML
87 lines
3.2 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
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<HTML>
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<HEAD>
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<TITLE>Reading Client Input in Apache 1.2</TITLE>
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</HEAD>
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<!-- Background white, links blue (unvisited), navy (visited), red (active) -->
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<BODY
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#000080"
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ALINK="#FF0000"
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>
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<!--#include virtual="header.html" -->
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<H1 ALIGN="CENTER">Reading Client Input in Apache 1.2</H1>
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<HR>
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<P>Apache 1.1 and earlier let modules handle POST and PUT requests by
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themselves. The module would, on its own, determine whether the
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request had an entity, how many bytes it was, and then called a
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function (<CODE>read_client_block</CODE>) to get the data.
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<P>However, HTTP/1.1 requires several things of POST and PUT request
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handlers that did not fit into this module, and all existing modules
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have to be rewritten. The API calls for handling this have been
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further abstracted, so that future HTTP protocol changes can be
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accomplished while remaining backwards-compatible.</P>
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<HR>
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<H3>The New API Functions</H3>
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<PRE>
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int ap_setup_client_block (request_rec *, int read_policy);
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int ap_should_client_block (request_rec *);
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long ap_get_client_block (request_rec *, char *buffer, int buffer_size);
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</PRE>
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<OL>
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<LI>Call <CODE>ap_setup_client_block()</CODE> near the beginning of the request
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handler. This will set up all the necessary properties, and
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will return either OK, or an error code. If the latter,
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the module should return that error code. The second parameter
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selects the policy to apply if the request message indicates a
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body, and how a chunked
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transfer-coding should be interpreted. Choose one of
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<PRE>
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REQUEST_NO_BODY Send 413 error if message has any body
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REQUEST_CHUNKED_ERROR Send 411 error if body without Content-Length
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REQUEST_CHUNKED_DECHUNK If chunked, remove the chunks for me.
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REQUEST_CHUNKED_PASS Pass the chunks to me without removal.
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</PRE>
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In order to use the last two options, the caller MUST provide a buffer
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large enough to hold a chunk-size line, including any extensions.
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<LI>When you are ready to possibly accept input, call
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<CODE>ap_should_client_block()</CODE>.
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This will tell the module whether or not to read input. If it is 0,
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the module should assume that the input is of a non-entity type
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(e.g. a GET request). A nonzero response indicates that the module
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should proceed (to step 3).
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This step also sends a 100 Continue response
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to HTTP/1.1 clients, so should not be called until the module
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is <STRONG>*definitely*</STRONG> ready to read content. (otherwise, the point of the
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100 response is defeated). Never call this function more than once.
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<LI>Finally, call <CODE>ap_get_client_block</CODE> in a loop. Pass it a
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buffer and its
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size. It will put data into the buffer (not necessarily the full
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buffer, in the case of chunked inputs), and return the length of
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the input block. When it is done reading, it will
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return 0 if EOF, or -1 if there was an error.
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</OL>
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<P>As an example, please look at the code in
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<CODE>mod_cgi.c</CODE>. This is properly written to the new API
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guidelines.</P>
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<!--#include virtual="footer.html" -->
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</BODY>
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</HTML>
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