requests: Do not leak header modifications when calling request. #947
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The requests() function takes a headers dict argument (call-by-reference). This object is then modified in the function. For instance the host is added and authentication information. Such behavior is not expected. It is also problematic: - Modifications of the header dictionary will be visible on the caller site. - When reusing the same (supposedly read-only) headers object for differenct calls, the second call will apparently re-use wrong headers from the previous call and may fail. This patch should also fix micropython#839. Unfortunately the copy operation does not preserve the key order and we have to touch the existing test cases. Signed-off-by: Richard Weickelt <[email protected]>
projectgus
approved these changes
Jan 17, 2025
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This looks good, thanks @rweickelt!
It looks like there's a slightly lower-resource-usage alternative where we don't add new entries to headers at all, but move all of those checks to when we're writing the response and write them all directly into the stream if they're not provided by the caller. But that approach would break up the flow of the function, and the improvement in memory usage would be very marginal.
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The requests() function takes a headers dict argument (call-by-reference). This object is then modified in the function. For instance the host is added and authentication information. Such behavior is not expected. It is also problematic:
This patch should also fix #839. Unfortunately the copy operation does not preserve the key order and we have to touch the existing test cases.