dgb: forward merkle-link builder (calculate_merkle_link) for tx-bearing won blocks - #302
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…ng won blocks calculate_merkle_link() is the exact inverse of share_check.hpp check_merkle_link(): given the block tx hashes it rebuilds the coinbase (index-0) merkle branch, using the same double-SHA combine and Bitcoin's duplicate-last-on-odd rule. A reconstructed won block recomputes its merkle ROOT from the gentx hash up the share m_merkle_link while the captured template txs only populate the body, so a coinbase-only link over a multi-tx body roots wrong and the daemon rejects bad-txnmrklroot. This builder lets the regtest forced-won seed rebuild m_merkle_link over the captured template tx set so a tx-bearing won block roots correctly -- the prerequisite for the multi-tx won-block re-soak. Test-only/fenced (src/impl/dgb only); no wire/share-format change. KAT round-trips through the PRODUCTION check_merkle_link across coinbase-only, even, and odd (duplicate-last) tx counts, every leaf index, and fail-closed on bad input. 4/4 green.
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Fail-closed regtest soak proving a won block carrying a non-coinbase funded legacy tx is reconstructed (#300/#302/#303) and ACCEPTED by a peer down BOTH arms (P2P primary + submitblock isolated). Asserts NTX>=2 and funded-txid presence per arm via getrawmempool/getblock; die() aborts on any miss (no getrawtransaction-without-txindex false-green path).
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Superseded by #303 (merged): won-block header merkle_root is recomputed over the actual reconstructed tx vector via build_block_merkle_root, which subsumes the forward calculate_merkle_link approach this PR proposed. No longer needed; closing to keep the queue clean. |
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Fail-closed regtest soak proving a won block carrying a non-coinbase funded legacy tx is reconstructed (#300/#302/#303) and ACCEPTED by a peer down BOTH arms (P2P primary + submitblock isolated). Asserts NTX>=2 and funded-txid presence per arm via getrawmempool/getblock; die() aborts on any miss (no getrawtransaction-without-txindex false-green path).
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What
New
coin/merkle_link_build.hpp—calculate_merkle_link(), the exact inverse ofshare_check.hpp check_merkle_link(). Given the block tx hashes it rebuilds the coinbase (index-0) merkle branch using the same double-SHA combine and Bitcoin's duplicate-last-on-odd rule.Why (the multi-tx won-block gap)
A reconstructed won block recomputes its merkle root from the gentx hash up the share
m_merkle_link(reconstruct_won_block.hpp:20-21), while the captured-template txs only populate the block body. So a coinbase-onlymerkle_linkover a multi-tx body roots to the wrong value and the daemon rejectsbad-txnmrklroot.The regtest
--regtest-force-won-shareseed synthesizes a coinbase-only link, so to drive a tx-bearing won-block re-soak (integrator: prove a real won block carrying mempool txs accepts at node B) itsm_merkle_linkmust be rebuilt over the captured template tx set.check_merkle_linkonly verifies a branch; nothing built one. This fills that gap.Scope
Test-only / fenced —
src/impl/dgb/only. No wire / share-format / p2pool-merged-v36 surface change (build-side helper; wire merkle_link semantics unchanged).Test
KAT round-trips through the production
dgb::check_merkle_link(not a re-impl): coinbase-only, even, and odd (duplicate-last) tx counts; every leaf index reproduces the one root; fail-closed on empty/out-of-range. 4/4 green locally.Follow-up (separate slice): wire
TemplateCapture(#300) + this builder into themain_dgbforced-won seed (capture GBTtransactions[], rebuildm_merkle_link, swaptemplate_other_txs_fnto the capture provider) and run the live multi-tx dual-arm re-soak.