[9678] Fix HTTP multipart parsing of chunked requests on Py3.7+ #1207
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bpo-29979's PR python/cpython#991 changed cgi.parse_multipart() to require a 'CONTENT-LENGTH' member in its `pdict` parameter (which is documented as "dictionary containing other parameters of the content type header"). The PR seems to have some issues: * The change seems to conflate `pdict` with an environment dict, probably because the test passes a dict called `env` as `pdict`. * 'CONTENT-LENGTH' isn't a customary parameter of the Content-Type header. `pdict` is intended to pass the multipart boundary [1]. * In a CGI environment the length of the request body is in the CONTENT_LENGTH variable, anyway [2]. Typo? * FieldStorage doesn't require a Content-Length header anyway! It's potionally used to enforce cgi.maxlen, which limits the requests size (because this is the layer for that, right?). #1012 dealt with bpo-29979's backward-incompatible change by passing the HTTP `Content-Length` header as the 'CONTENT-LENGTH' member of `pdict` when the header exists. When the header isn't given, Request skips parsing the request content. The problem is that in the Twisted context, unlike the CGI context (where the web server is responsible for removing any transfer encodings), that header won't necessarily exist. For example, when a chunked transfer encoding is used by the client. This commit does the simplest possible thing: synthesize the content length based on what was actually received. [1]: https://tools.ietf.org/html/rfc7578#section-4.1 [2]: https://tools.ietf.org/html/rfc3875#section-4.1.2
Also add a reference to python/cpython#8530
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approved these changes
Jan 9, 2020
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See a562242 for a detailed explanation. This is the simplest possible fix. I do think that we should probably ditch the
cgimodule for multipart parsing eventually because it is verystr-oriented, but we wantbytes.This includes the tests from #1180. Thank you @msdemlei!
Contributor Checklist:
reviewto the keywords field in Trac, and putting a link to this PR in the comment; it shows up in https://twisted.reviews/ now.