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dgb(stratum): emit only the won-block body the frozen header commits to (G3b bad-txnmrklroot) #815

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Merged
frstrtr merged 1 commit into from
Jul 23, 2026
Merged

dgb(stratum): emit only the won-block body the frozen header commits to (G3b bad-txnmrklroot) #815

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4 changes: 2 additions & 2 deletions .github/workflows/build.yml
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Original file line number Diff line number Diff line change
Expand Up @@ -147,7 +147,7 @@ jobs:
test_mweb_builder \
test_address_resolution test_compute_share_target test_web_honesty_regression \
test_utxo test_dgb_subsidy test_dgb_coinbase_value dgb_share_test dgb_redistribute_test dgb_block_assembly_test dgb_witness_commitment_test dgb_header_sample_build_test dgb_header_ingest_test dgb_mempool_ingest_test \
dgb_gentx_coinbase_test dgb_connection_coinbase_test dgb_pplns_payout_split_test nmc_auxpow_merkle_test nmc_template_builder_test nmc_underfill_guard_test nmc_auxpow_wire_test nmc_reconstruct_won_block_test nmc_mempool_name_test nmc_block_broadcast_test nmc_host_dualpath_test nmc_fallback_path_conformance_test dgb_gentx_share_path_test dgb_conn_pplns_producer_test dgb_other_tx_resolver_test \
dgb_gentx_coinbase_test dgb_connection_coinbase_test dgb_won_block_serialize_test dgb_pplns_payout_split_test nmc_auxpow_merkle_test nmc_template_builder_test nmc_underfill_guard_test nmc_auxpow_wire_test nmc_reconstruct_won_block_test nmc_mempool_name_test nmc_block_broadcast_test nmc_host_dualpath_test nmc_fallback_path_conformance_test dgb_gentx_share_path_test dgb_conn_pplns_producer_test dgb_other_tx_resolver_test \
dgb_other_tx_assembler_test dgb_reconstruct_won_block_test dgb_reconstruct_closure_test dgb_gentx_unpack_test dgb_work_source_test dgb_template_builder_test dgb_embedded_coin_node_test dgb_embedded_tx_select_test dgb_template_other_txs_test dgb_coinbase_value_parity_test dgb_submit_classify_test dgb_aux_parent_coinbase_parity_test dgb_template_capture_test dgb_aux_doge_db_commitment_bind_test dgb_aux_doge_mm_commitment_test dgb_aux_doge_dc_proof_test dgb_aux_doge_bind_parsers_test dgb_compact_blocks_bip152_parity_test dgb_aux_dual_target_select_test dgb_aux_broadcast_path_election_test dgb_aux_doge_submit_test dgb_aux_doge_embed_livewire_test dgb_aux_doge_dc_layout_verifier_test \
rpc_request_test softfork_check_test genesis_check_test algo_select_test digishield_walk_test header_chain_test \
dgb_coin_node_seam_test dgb_block_broadcast_test dgb_won_block_dispatch_test dgb_forced_won_share_dualpath_test dgb_scrypt_pow_test dgb_nonce_grinder_test dgb_regrind_block_test dgb_won_block_finalize_test dgb_share_target_genesis_test dgb_share_target_retarget_test dgb_share_bits_oracle_pin_test dgb_pool_msg_wire_test dgb_get_shares_walk_test dgb_download_stops_test dgb_think_p1_walk_bounds_test dgb_think_p1_desired_emit_test dgb_think_p6_desired_cutoff_test dgb_think_p4_head_keys_test dgb_think_p3_best_head_test dgb_g1_oracle_byte_parity_test dgb_think_p2_walk_bounds_test dgb_expected_time_to_block_test dgb_tail_score_endpoints_test dgb_pool_attempts_per_second_test dgb_pool_efficiency_test dgb_think_p5_best_share_punish_test dgb_auto_ratchet_tail_guard_test dgb_auto_ratchet_sim_test dgb_binomial_conf_interval_test dgb_desired_version_tally_test dgb_min_protocol_ratchet_test dgb_get_height_and_last_endpoints_test dgb_chain_walk_window_test dgb_redistribute_delegate_ghal_test dgb_share_weight_decay_test dgb_naughty_propagation_test dgb_hash_format_parity_test dgb_emergency_decay_saturation_test dgb_arith256_muldiv_kat_test v37_test \
Expand Down Expand Up @@ -328,7 +328,7 @@ jobs:
test_mweb_builder \
test_address_resolution test_compute_share_target test_web_honesty_regression \
test_utxo test_dgb_subsidy test_dgb_coinbase_value dgb_share_test dgb_redistribute_test dgb_block_assembly_test dgb_witness_commitment_test dgb_header_sample_build_test dgb_header_ingest_test dgb_mempool_ingest_test \
dgb_gentx_coinbase_test dgb_connection_coinbase_test dgb_pplns_payout_split_test nmc_auxpow_merkle_test nmc_template_builder_test nmc_underfill_guard_test nmc_auxpow_wire_test nmc_reconstruct_won_block_test nmc_mempool_name_test nmc_block_broadcast_test nmc_host_dualpath_test nmc_fallback_path_conformance_test dgb_gentx_share_path_test dgb_conn_pplns_producer_test dgb_other_tx_resolver_test \
dgb_gentx_coinbase_test dgb_connection_coinbase_test dgb_won_block_serialize_test dgb_pplns_payout_split_test nmc_auxpow_merkle_test nmc_template_builder_test nmc_underfill_guard_test nmc_auxpow_wire_test nmc_reconstruct_won_block_test nmc_mempool_name_test nmc_block_broadcast_test nmc_host_dualpath_test nmc_fallback_path_conformance_test dgb_gentx_share_path_test dgb_conn_pplns_producer_test dgb_other_tx_resolver_test \
dgb_other_tx_assembler_test dgb_reconstruct_won_block_test dgb_reconstruct_closure_test dgb_gentx_unpack_test dgb_work_source_test dgb_template_builder_test dgb_embedded_coin_node_test dgb_embedded_tx_select_test dgb_template_other_txs_test dgb_coinbase_value_parity_test dgb_submit_classify_test dgb_aux_parent_coinbase_parity_test dgb_template_capture_test dgb_aux_doge_db_commitment_bind_test dgb_aux_doge_mm_commitment_test dgb_aux_doge_dc_proof_test dgb_aux_doge_bind_parsers_test dgb_compact_blocks_bip152_parity_test dgb_aux_dual_target_select_test dgb_aux_broadcast_path_election_test dgb_aux_doge_submit_test dgb_aux_doge_embed_livewire_test dgb_aux_doge_dc_layout_verifier_test \
rpc_request_test softfork_check_test genesis_check_test algo_select_test digishield_walk_test header_chain_test \
dgb_coin_node_seam_test dgb_block_broadcast_test dgb_won_block_dispatch_test dgb_forced_won_share_dualpath_test dgb_scrypt_pow_test dgb_nonce_grinder_test dgb_regrind_block_test dgb_won_block_finalize_test dgb_share_target_genesis_test dgb_share_target_retarget_test dgb_share_bits_oracle_pin_test dgb_pool_msg_wire_test dgb_get_shares_walk_test dgb_download_stops_test dgb_think_p1_walk_bounds_test dgb_think_p1_desired_emit_test dgb_think_p6_desired_cutoff_test dgb_think_p4_head_keys_test dgb_think_p3_best_head_test dgb_g1_oracle_byte_parity_test dgb_think_p2_walk_bounds_test dgb_expected_time_to_block_test dgb_tail_score_endpoints_test dgb_pool_attempts_per_second_test dgb_pool_efficiency_test dgb_think_p5_best_share_punish_test dgb_auto_ratchet_tail_guard_test dgb_auto_ratchet_sim_test dgb_binomial_conf_interval_test dgb_desired_version_tally_test dgb_min_protocol_ratchet_test dgb_get_height_and_last_endpoints_test dgb_chain_walk_window_test dgb_redistribute_delegate_ghal_test dgb_share_weight_decay_test dgb_naughty_propagation_test dgb_hash_format_parity_test dgb_emergency_decay_saturation_test dgb_arith256_muldiv_kat_test test_coin_broadcaster test_multiaddress_pplns test_pplns_stress \
Expand Down
158 changes: 158 additions & 0 deletions src/impl/dgb/coin/won_block_serialize.hpp
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// SPDX-License-Identifier: AGPL-3.0-or-later
#pragma once
// ---------------------------------------------------------------------------
// dgb::coin::serialize_won_block -- the won-block wire serializer for the
// Stratum submit path (work_source.cpp mining_submit / #82 dual-path sink).
//
// THE BLOCKER it closes (G3b, bad-txnmrklroot on the empty-embedded-chain
// won block): the reconstruct path hand-rolled the block framing and could
// emit a body the ALREADY-HASHED header does not commit to. Two divergences
// live here, both of which digibyted rejects and neither of which the header
// can be re-derived around (the miner hashed the merkle root already -- any
// post-hoc coinbase mutation invalidates the PoW binding):
//
// 1. TX-SET vs COMMITMENT. The header merkle root is the ascent of the
// FROZEN stratum merkle branches from the coinbase txid. When the job
// carried NO branches (the empty-embedded-chain case: the branch cache
// at get_stratum_merkle_branches() is still a Stage-4c stub returning
// {}) the committed root IS the bare coinbase txid -- i.e. the miner
// committed to a COINBASE-ONLY block. Appending job->tx_data anyway
// produces a body whose recomputed root cannot match -> bad-txnmrklroot,
// deterministically. The only correct emission is the committed one:
// coinbase-only. Dropping the extra txs forfeits their fees; shipping
// them forfeits the whole block. We ship the block.
//
// 2. BIP144 WITNESS FORM vs BIP141 COMMITMENT. A witness-shaped coinbase
// is only legal when it carries the BIP141 commitment output
// (OP_RETURN 0x24 aa21a9ed <32B>); Core's CheckWitnessMalleation rejects
// a witness-bearing coinbase without one (unexpected-witness). The
// PPLNS connection coinbase only carries the commitment when the
// producer seam populates segwit_commitment_script (gentx_coinbase.hpp)
// -- on the empty-chain path it does not. Emitting the marker/flag
// regardless is therefore a second guaranteed reject. A coinbase-only /
// all-legacy block needs no witness at all and Core accepts the legacy
// serialization on a segwit-active chain, so the rule is: witness form
// IFF the coinbase actually carries the commitment. Injecting the
// commitment here is NOT an option -- it changes the coinbase txid and
// breaks the header the miner already hashed. The commitment must be
// present at JOB-BUILD time (coinb2), which is the producer-seam slice.
//
// Pure + byte-level (no tx codec, no chain state), so it is directly KAT-able
// against hand-built vectors. Per-coin isolation: src/impl/dgb/ only; no
// core/ or shared-layer surface. p2pool-merged-v36 surface: NONE -- this is
// parent-block (daemon-facing) framing, not share format / PoW / PPLNS.
// ---------------------------------------------------------------------------

#include <cstddef>
#include <cstdint>
#include <vector>

namespace dgb::coin
{

// BIP141 commitment scriptPubKey prefix: OP_RETURN PUSH36 aa21a9ed.
inline constexpr uint8_t kWitnessCommitmentPrefix[6] = {0x6a, 0x24, 0xaa, 0x21, 0xa9, 0xed};

// True iff the coinbase NON-witness serialization carries a BIP141 witness
// commitment output. Byte-scan for the 6-byte scriptPubKey prefix followed by
// the 32-byte commitment -- the same shape Core scans for in
// GetWitnessCommitmentIndex(), without pulling in the tx codec.
inline bool coinbase_has_witness_commitment(const std::vector<uint8_t>& coinbase)
{
if (coinbase.size() < sizeof(kWitnessCommitmentPrefix) + 32)
return false;
const size_t last = coinbase.size() - (sizeof(kWitnessCommitmentPrefix) + 32);
for (size_t i = 0; i <= last; ++i) {
bool hit = true;
for (size_t j = 0; j < sizeof(kWitnessCommitmentPrefix); ++j) {
if (coinbase[i + j] != kWitnessCommitmentPrefix[j]) { hit = false; break; }
}
if (hit) return true;
}
return false;
}

// BIP144 reserialization of the coinbase: marker/flag after the 4-byte version
// and a single 32-byte all-zero reserved witness item before the 4-byte
// locktime. The txid is UNCHANGED (txid is defined over the non-witness
// bytes), so the header merkle root stays valid.
inline std::vector<uint8_t> to_bip144_coinbase(const std::vector<uint8_t>& coinbase)
{
std::vector<uint8_t> out;
out.reserve(coinbase.size() + 36);
out.insert(out.end(), coinbase.begin(), coinbase.begin() + 4); // version
out.push_back(0x00); // marker
out.push_back(0x01); // flag
out.insert(out.end(), coinbase.begin() + 4, coinbase.end() - 4); // vin/vout
out.push_back(0x01); // stack_count = 1
out.push_back(0x20); // item_len = 32
out.insert(out.end(), 32, 0x00); // reserved value
out.insert(out.end(), coinbase.end() - 4, coinbase.end()); // locktime
return out;
}

struct WonBlockAssembly
{
std::vector<uint8_t> bytes; // full block wire bytes
size_t tx_count{0}; // txs actually serialized (incl. coinbase)
bool witness_form{false}; // coinbase emitted BIP144?
size_t dropped_txs{0}; // body txs the header does not commit to
bool witness_form_suppressed{false}; // segwit_active but no BIP141 commitment
};

// Serialize header || varint(tx_count) || coinbase[+witness] || other_txs,
// enforcing the two invariants documented at the top of this file.
//
// committed_coinbase_only == "the job carried NO merkle branches", i.e. the
// header merkle root IS the bare coinbase txid.
inline WonBlockAssembly serialize_won_block(
const std::vector<uint8_t>& header80,
const std::vector<uint8_t>& coinbase,
const std::vector<std::vector<uint8_t>>& other_txs,
bool segwit_active,
bool committed_coinbase_only)
{
WonBlockAssembly out;

// (1) Emit only the tx set the frozen header actually commits to.
const std::vector<std::vector<uint8_t>> kNone;
const bool drop = committed_coinbase_only && !other_txs.empty();
const std::vector<std::vector<uint8_t>>& body = drop ? kNone : other_txs;
out.dropped_txs = drop ? other_txs.size() : 0;

// (2) Witness form IFF the coinbase carries the BIP141 commitment.
const bool has_commitment = coinbase_has_witness_commitment(coinbase);
out.witness_form = segwit_active && has_commitment && coinbase.size() >= 8;
out.witness_form_suppressed = segwit_active && !out.witness_form;

const std::vector<uint8_t> cb =
out.witness_form ? to_bip144_coinbase(coinbase) : coinbase;

out.tx_count = 1 + body.size();

size_t body_bytes = 0;
for (const auto& tx : body) body_bytes += tx.size();
out.bytes.reserve(header80.size() + 9 + cb.size() + body_bytes);
out.bytes.insert(out.bytes.end(), header80.begin(), header80.end());

// tx-count varint (Bitcoin CompactSize).
const uint64_t n = out.tx_count;
if (n < 0xfd) {
out.bytes.push_back(static_cast<uint8_t>(n));
} else if (n <= 0xffff) {
out.bytes.push_back(0xfd);
out.bytes.push_back(static_cast<uint8_t>(n & 0xff));
out.bytes.push_back(static_cast<uint8_t>((n >> 8) & 0xff));
} else {
out.bytes.push_back(0xfe);
for (int i = 0; i < 4; ++i)
out.bytes.push_back(static_cast<uint8_t>((n >> (8 * i)) & 0xff));
}

out.bytes.insert(out.bytes.end(), cb.begin(), cb.end());
for (const auto& tx : body)
out.bytes.insert(out.bytes.end(), tx.begin(), tx.end());
return out;
}

} // namespace dgb::coin
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