Fix some compression bugs in dns. #4813
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- A compression pointer is when the two higher bits are set, the code was considering only 0xC0 as a pointer, where in reality anything from 0xC0-0xFF is a pointer, probably went unnoticed since you need big packets to have long pointers. - Make sure we can access the lower byte of the pointer by checking len, the code was careful to not access past the first byte, but ignored the second. - As per RFC9267 make sure a pointer only points backwards, this one is not so bad, as the code had a iteration_max that ended up guarding against infinite jumps. Lightly tested, some eyes are welcome, but these are remote DOSable.
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I'm writing a recursive resolver in odin and eyeballed the compression code and noticed these. |
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Lightly tested, some eyes are welcome, but these are likely remote DOSable.