headerssync: carry indexer proofs in CompressedHeader, bound redownload buffer by bytes - #23
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CompressedHeader dropped indexerProof, so GetFullHeader rebuilt an indexer header with no proof attached. Downstream, CheckProofOfWork rejects indexer blocks without a proof and AcceptBlockHeader treats the peer's chain as invalid, aborting any headers sync that crosses the FIP-101 indexer range. Preserve the proof alongside auxpow so reconstructed headers are complete. Also, auxpow headers carry a parent coinbase transaction plus Merkle branches and are not fixed at 80 bytes, so REDOWNLOAD_BUFFER_SIZE (a header count) does not bound redownload-buffer memory. Track the serialized size of buffered headers and abort the sync once the buffer exceeds 64 MiB.
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Two issues in the headers-sync anti-DoS logic for Fractal block types:
CompressedHeaderdropped theindexerProofwhen compressing anindexer block header, and
GetFullHeaderreconstructed the headerwithout it. During the redownload phase the peer is asked to resend
full headers, and a headers chain containing indexer blocks could not
round-trip through the compressed representation correctly.
The redownload buffer was bounded only by the header count
(
m_redownload_buffer_size, one entry per header), not by serializedsize. Fractal headers can carry arbitrarily large AuxPoW data plus an
indexer proof, so a fixed count of headers is no longer a meaningful
memory bound. A malicious headers-sync peer could force buffering of
far more memory than the anti-DoS design intends.
This change:
indexerProofmember toCompressedHeader(constructed fromthe full header, restored by
GetFullHeader), and extends the equalityoperator accordingly.
m_redownload_buffer_bytesand rejects the peer (turning the sync intoa failure) once the buffer exceeds 64 MiB.
No consensus or wire-protocol changes; this only hardens the local
headers-sync state machine. Fuzzed with the
headers_sync_statetarget(545k executions under AddressSanitizer, no findings).