Fix buffer size in large-blobs response #25
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This patch removes the unused REALISTIC_MAX_MESSAGE_SIZE constant. Its value has no inherent meaning, and applications should not rely on it. In fact, implementations in the Trussed ecosystem typically use a max message size of 3072, see usbd-ctaphid.
The buffer size used in the response to the large-blobs command should match the maximum message size of the FIDO2 implementation (minus 64). At the same time, the buffer size must be hardcoded because serde-indexed does not support const generics. As a temporary workaround, this patch changes the default buffer size to zero (to reduce stack usage if the extension is not used) and sets the buffer size to 3008 if the large-blobs feature is activated (matching the max message size declared by usbd-ctaphid that is used in solo2 and nitrokey-3-firmware).
sosthene-nitrokey
approved these changes
Nov 29, 2023
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The buffer size used in the response to the large-blobs command should match the maximum message size of the FIDO2 implementation (minus 64). At the same time, the buffer size must be hardcoded because serde-indexed does not support const generics. As a temporary workaround, this PR changes the default buffer size to zero (to reduce stack usage if the extension is not used) and sets the buffer size to 3008 if the large-blobs feature is activated (matching the max message size declared by usbd-ctaphid that is used in solo2 and nitrokey-3-firmware).
This PR also removes the
REALISTIC_MAX_MESSAGE_SIZEas it is unused inctap-typesand does not have any significance for other crates either.