Prevent division by zero in QPACK Required Insert Count reconstruction - #549
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Summary
Handle QPACK Required Insert Count reconstruction when the decoder dynamic table cannot hold a single entry.
Details
When
hard_max_dtable_capacityis smaller thanNGHTTP3_QPACK_ENTRY_OVERHEAD, the calculated number of entries is zero. For a nonzero encoded Required Insert Count, the reconstruction logic previously computedfull == 0and then divided byfull, causing a division-by-zero crash.This patch:
NGHTTP3_ERR_QPACK_DECOMPRESSION_FAILED.Security Impact
A malformed peer-controlled QPACK header block could crash the decoder process. The invalid input is now rejected safely.