dgb: parity KAT for GBT prevhash formatter u256_be_display_hex

.github/workflows/build.yml

@@ -84,7 +84,7 @@ jobs:
                     dgb_gentx_coinbase_test dgb_connection_coinbase_test dgb_pplns_payout_split_test nmc_auxpow_merkle_test nmc_template_builder_test nmc_auxpow_wire_test nmc_reconstruct_won_block_test nmc_mempool_name_test nmc_block_broadcast_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_dc_proof_test dgb_aux_doge_bind_parsers_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_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_binomial_conf_interval_test dgb_desired_version_tally_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 v37_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_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_binomial_conf_interval_test dgb_desired_version_tally_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 v37_test \
             -j$(nproc)
 
       - name: Run tests
@@ -216,7 +216,7 @@ jobs:
                     dgb_gentx_coinbase_test dgb_connection_coinbase_test dgb_pplns_payout_split_test nmc_auxpow_merkle_test nmc_template_builder_test nmc_auxpow_wire_test nmc_reconstruct_won_block_test nmc_mempool_name_test nmc_block_broadcast_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_dc_proof_test dgb_aux_doge_bind_parsers_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_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_binomial_conf_interval_test dgb_desired_version_tally_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 test_coin_broadcaster test_multiaddress_pplns test_pplns_stress \
+                    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_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_binomial_conf_interval_test dgb_desired_version_tally_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 test_coin_broadcaster test_multiaddress_pplns test_pplns_stress \
                     v37_test \
             -j$(nproc)
 

src/impl/dgb/test/CMakeLists.txt

@@ -760,6 +760,21 @@ if (BUILD_TESTING AND GTest_FOUND)
     target_link_libraries(dgb_binomial_conf_interval_test PRIVATE
         GTest::gtest_main GTest::gtest)
     gtest_add_tests(dgb_binomial_conf_interval_test "" AUTO)
+    # dgb_hash_format_parity_test: FENCED, additive KAT pinning the pure GBT
+    # block-hash display formatter coin/hash_format.hpp u256_be_display_hex
+    # (most-significant-limb-first 64-hex render of the LE u256, the encoding
+    # both work paths emit for "previousblockhash"). NON-CIRCULAR anchor = the
+    # DGB mainnet genesis hash pinned at p2pool-dgb-scrypt
+    # bitcoin/networks/digibyte.py:55; the test reverses that external display
+    # constant into LE storage bytes, feeds u256::from_le_bytes, and asserts the
+    # formatter reproduces it byte for byte. DIAGNOSTICS/wire-display only, no
+    # consensus surface. Pure header (<cstdint>/<string>) -> links only GTest.
+    # No call site rewired. MUST also be in the build.yml --target allowlist
+    # (#143 NOT_BUILT trap).
+    add_executable(dgb_hash_format_parity_test hash_format_parity_test.cpp)
+    target_link_libraries(dgb_hash_format_parity_test PRIVATE
+        GTest::gtest_main GTest::gtest)
+    gtest_add_tests(dgb_hash_format_parity_test "" AUTO)
     # dgb_desired_version_tally_test: FENCED, additive KAT pinning the
     # version->work / version->count accumulation core lifted into
     # coin/desired_version_tally.hpp vs the p2pool-dgb-scrypt data.py:918-922

src/impl/dgb/test/hash_format_parity_test.cpp

@@ -0,0 +1,132 @@
+// ---------------------------------------------------------------------------
+// dgb_hash_format_parity_test -- FENCED, additive KAT pinning the pure GBT
+// block-hash display formatter dgb::coin::u256_be_display_hex lifted into
+// coin/hash_format.hpp.
+//
+// u256_be_display_hex renders a 256-bit value (coin/dgb_arith256.hpp u256, a
+// little-endian limb array with limb[0] least-significant) as the
+// GBT-conventional big-endian display hex: most-significant limb first, 64
+// lowercase hex digits, no 0x prefix -- the encoding the stratum work source
+// and the embedded work path both emit for "previousblockhash". A 1-nibble
+// divergence in limb/byte ordering there means the two callers of
+// build_work_template could emit a prevhash the parent daemon never accepts.
+//
+// The anchor is NON-CIRCULAR: the DigiByte mainnet genesis block hash
+// 7497ea1b465eb39f1c8f507bc877078fe016d6fcb6dfad3a64c98dcc6e1e8496 is the
+// external constant the DGB oracle pins at frstrtr/p2pool-dgb-scrypt
+// bitcoin/networks/digibyte.py:55 (helper.check_block_header(..., 'genesis')).
+// The test parses that literal display hex into 32 MSB-first bytes with an
+// independent hex reader, reverses to the on-the-wire little-endian byte order,
+// feeds u256::from_le_bytes (the exact storage path a real tip hash takes), and
+// asserts u256_be_display_hex reproduces the original oracle string byte for
+// byte. The formatter under test is the only code computing the output.
+//
+// DIAGNOSTICS / WIRE-DISPLAY ONLY: no consensus surface, no payout/subsidy/
+// version-gate value. Pure header (<cstdint>/<string>) -> links only GTest. No
+// call site rewired. MUST also be in BOTH build.yml --target allowlists
+// (#143 NOT_BUILT trap).
+// ---------------------------------------------------------------------------
+
+#include <gtest/gtest.h>
+
+#include <array>
+#include <cstdint>
+#include <string>
+
+#include "../coin/hash_format.hpp"
+
+using dgb::coin::u256;
+using dgb::coin::u256_be_display_hex;
+
+namespace {
+
+// Independent hex reader (does NOT share the formatter's nibble/limb logic):
+// parse a 64-char big-endian display hex string into 32 MSB-first bytes.
+std::array<unsigned char, 32> be_hex_to_msb_bytes(const std::string& hex)
+{
+    EXPECT_EQ(hex.size(), 64u);
+    auto nib = [](char c) -> int {
+        if (c >= '0' && c <= '9') return c - '0';
+        if (c >= 'a' && c <= 'f') return c - 'a' + 10;
+        if (c >= 'A' && c <= 'F') return c - 'A' + 10;
+        return -1;
+    };
+    std::array<unsigned char, 32> out{};
+    for (int i = 0; i < 32; ++i)
+        out[i] = (unsigned char)((nib(hex[2 * i]) << 4) | nib(hex[2 * i + 1]));
+    return out;
+}
+
+// Build a u256 from a big-endian display hex string via the production
+// from_le_bytes path: reverse MSB-first display bytes into little-endian
+// storage order (the byte order a parsed tip hash actually arrives in).
+u256 u256_from_display_hex(const std::string& hex)
+{
+    auto msb = be_hex_to_msb_bytes(hex);
+    unsigned char le[32];
+    for (int i = 0; i < 32; ++i) le[i] = msb[31 - i];
+    return u256::from_le_bytes(le);
+}
+
+} // namespace
+
+// Oracle anchor: the DGB mainnet genesis hash (digibyte.py:55) must round-trip
+// through the LE storage path back to its canonical display hex.
+TEST(DgbHashFormatParity, GenesisHashRendersOracleDisplayHex)
+{
+    const std::string genesis =
+        "7497ea1b465eb39f1c8f507bc877078fe016d6fcb6dfad3a64c98dcc6e1e8496";
+    EXPECT_EQ(u256_be_display_hex(u256_from_display_hex(genesis)), genesis);
+}
+
+// Zero renders 64 zero nibbles -- no truncation, full left-padding.
+TEST(DgbHashFormatParity, ZeroRendersSixtyFourZeros)
+{
+    EXPECT_EQ(u256_be_display_hex(u256{}), std::string(64, '0'));
+}
+
+// A tiny value pins the left zero-padding and that limb[0] is the LOW nibble.
+TEST(DgbHashFormatParity, OneRendersPaddedToSixtyFourDigits)
+{
+    u256 v;
+    v.limb[0] = 1;
+    EXPECT_EQ(u256_be_display_hex(v), std::string(63, '0') + "1");
+}
+
+// Distinct per-limb values pin most-significant-limb-FIRST ordering (limb[3]
+// is the leading 16 hex digits, limb[0] the trailing 16).
+TEST(DgbHashFormatParity, LimbOrderingMostSignificantFirst)
+{
+    u256 v;
+    v.limb[3] = 0x0123456789abcdefULL;
+    v.limb[2] = 0xfedcba9876543210ULL;
+    v.limb[1] = 0x00000000ffffffffULL;
+    v.limb[0] = 0xdeadbeefcafef00dULL;
+    EXPECT_EQ(u256_be_display_hex(v),
+              "0123456789abcdef"
+              "fedcba9876543210"
+              "00000000ffffffff"
+              "deadbeefcafef00d");
+}
+
+// All-ones renders 64 'f' nibbles (every limb fully populated).
+TEST(DgbHashFormatParity, AllOnesRendersSixtyFourEffs)
+{
+    u256 v;
+    for (int i = 0; i < 4; ++i) v.limb[i] = 0xffffffffffffffffULL;
+    EXPECT_EQ(u256_be_display_hex(v), std::string(64, 'f'));
+}
+
+// from_le_bytes with a fully-distinct 0x00..0x1f pattern pins the byte
+// reversal: LE byte 0 (0x00) is the LOW byte -> trailing "00", LE byte 31
+// (0x1f) is the HIGH byte -> leading "1f".
+TEST(DgbHashFormatParity, FromLeBytesByteReversalIsBigEndianDisplay)
+{
+    unsigned char le[32];
+    for (int i = 0; i < 32; ++i) le[i] = (unsigned char)i;
+    EXPECT_EQ(u256_be_display_hex(u256::from_le_bytes(le)),
+              "1f1e1d1c1b1a1918"
+              "1716151413121110"
+              "0f0e0d0c0b0a0908"
+              "0706050403020100");
+}