Zstandard data is incomplete on HEAD requests

[AlexMili]

Tried to do a HEAD request with a server answering with zstd encoding by default but since the content is empty ZStandardDecoder is raising DecodingError("Zstandard data is incomplete") when calling flush().

Tried to fix the problem by adding a check if ret is empty:

    def flush(self) -> bytes:
        ret = self.decompressor.flush()  # note: this is a no-op
        # If content is empty, no need to wait for EOF
        if not self.decompressor.eof and len(ret) > 0:
            raise DecodingError("Zstandard data is incomplete")  # pragma: no cover
        return bytes(ret)

Don't know if there is an other way to avoid the error or fix it but sounds like a bug.

[tomchristie]

Thanks seems viable. Can you point at a live URL to replicate?

[AlexMili]

You can try https://password-hashing.net/ or https://3proxy.org/.

Source: AlexMili/Reachable#8