dash: MSVC-portable coinbase PPLNS payout muldiv (fixes c2pool-dash Windows v0.2.1)

.github/workflows/build.yml

@@ -114,7 +114,7 @@ jobs:
                     core_test sharechain_test share_test btc_share_test \
                     test_threading test_weights \
                     test_header_chain test_mempool test_template_builder \
-                    test_doge_chain test_compact_blocks test_dash_x11_kat test_dash_header_chain test_dash_block_replay test_dash_conformance test_dash_subsidy test_dash_mempool test_dash_simplifiedmns test_dash_quorum test_dash_quorum_root test_dash_mn_state test_dash_embedded_gbt test_dash_smldiff test_dash_p2p_messages test_dash_p2p_connection test_dash_p2p_node test_dash_node_interface test_dash_config test_dash_broadcaster test_dash_broadcaster_full test_dash_share_hash_link test_dash_block_relay test_dash_rpc_request test_dash_rpc_conf test_dash_block_producer test_dash_embedded_relay_e2e test_dash_block_relay_plan test_dash_version_activation_latch test_dash_block_relay_binding test_dash_block_relay_dual_arm test_dash_coinbase_parity test_dash_donation_combined test_dash_g3_assembled test_dash_work_target test_dash_work_job_targets test_dash_stratum_binding test_dash_job_notify_roundtrip test_dash_cb_payee test_dash_stratum_notify_roundtrip test_dash_poolnode_messages test_dash_peer test_dash_share_tracker test_dash_node test_dash_share_messages test_dash_stratum_extranonce_split test_dash_stratum_submit_reassembly test_dash_difficulty_parity test_dash_auto_ratchet test_dash_min_protocol_gate test_dash_work_source test_dash_node_coin_state test_dash_coin_state_maintainer test_dash_node_embedded_wire test_dash_node_reception_wire test_dash_get_work \
+                    test_doge_chain test_compact_blocks test_dash_x11_kat test_dash_header_chain test_dash_block_replay test_dash_conformance test_dash_subsidy test_dash_mempool test_dash_simplifiedmns test_dash_quorum test_dash_quorum_root test_dash_mn_state test_dash_embedded_gbt test_dash_smldiff test_dash_p2p_messages test_dash_p2p_connection test_dash_p2p_node test_dash_node_interface test_dash_config test_dash_broadcaster test_dash_broadcaster_full test_dash_share_hash_link test_dash_block_relay test_dash_rpc_request test_dash_rpc_conf test_dash_block_producer test_dash_embedded_relay_e2e test_dash_block_relay_plan test_dash_version_activation_latch test_dash_block_relay_binding test_dash_block_relay_dual_arm test_dash_coinbase_parity test_dash_coinbase_muldiv test_dash_donation_combined test_dash_g3_assembled test_dash_work_target test_dash_work_job_targets test_dash_stratum_binding test_dash_job_notify_roundtrip test_dash_cb_payee test_dash_stratum_notify_roundtrip test_dash_poolnode_messages test_dash_peer test_dash_share_tracker test_dash_node test_dash_share_messages test_dash_stratum_extranonce_split test_dash_stratum_submit_reassembly test_dash_difficulty_parity test_dash_auto_ratchet test_dash_min_protocol_gate test_dash_work_source test_dash_node_coin_state test_dash_coin_state_maintainer test_dash_node_embedded_wire test_dash_node_reception_wire test_dash_get_work \
                     test_multiaddress_pplns test_pplns_stress \
                     test_hash_link test_decay_pplns \
                     test_pplns_consensus \
@@ -264,7 +264,7 @@ jobs:
                     test_threading test_weights \
                     test_header_chain test_mempool test_template_builder \
                     test_doge_chain test_compact_blocks test_dash_x11_kat \
-                    test_dash_header_chain test_dash_block_replay test_dash_conformance test_dash_subsidy test_dash_mempool test_dash_simplifiedmns test_dash_quorum test_dash_quorum_root test_dash_mn_state test_dash_embedded_gbt test_dash_smldiff test_dash_p2p_messages test_dash_p2p_connection test_dash_p2p_node test_dash_node_interface test_dash_config test_dash_broadcaster test_dash_broadcaster_full test_dash_share_hash_link test_dash_block_relay test_dash_rpc_request test_dash_rpc_conf test_dash_block_producer test_dash_embedded_relay_e2e test_dash_block_relay_plan test_dash_version_activation_latch test_dash_block_relay_binding test_dash_block_relay_dual_arm test_dash_coinbase_parity test_dash_donation_combined test_dash_g3_assembled test_dash_work_target test_dash_work_job_targets test_dash_stratum_binding test_dash_job_notify_roundtrip test_dash_cb_payee test_dash_stratum_notify_roundtrip test_dash_poolnode_messages test_dash_peer test_dash_share_tracker test_dash_node test_dash_share_messages test_dash_stratum_extranonce_split test_dash_stratum_submit_reassembly test_dash_difficulty_parity test_dash_auto_ratchet test_dash_min_protocol_gate test_dash_work_source test_dash_node_coin_state test_dash_coin_state_maintainer test_dash_node_embedded_wire test_dash_node_reception_wire test_dash_get_work \
+                    test_dash_header_chain test_dash_block_replay test_dash_conformance test_dash_subsidy test_dash_mempool test_dash_simplifiedmns test_dash_quorum test_dash_quorum_root test_dash_mn_state test_dash_embedded_gbt test_dash_smldiff test_dash_p2p_messages test_dash_p2p_connection test_dash_p2p_node test_dash_node_interface test_dash_config test_dash_broadcaster test_dash_broadcaster_full test_dash_share_hash_link test_dash_block_relay test_dash_rpc_request test_dash_rpc_conf test_dash_block_producer test_dash_embedded_relay_e2e test_dash_block_relay_plan test_dash_version_activation_latch test_dash_block_relay_binding test_dash_block_relay_dual_arm test_dash_coinbase_parity test_dash_coinbase_muldiv test_dash_donation_combined test_dash_g3_assembled test_dash_work_target test_dash_work_job_targets test_dash_stratum_binding test_dash_job_notify_roundtrip test_dash_cb_payee test_dash_stratum_notify_roundtrip test_dash_poolnode_messages test_dash_peer test_dash_share_tracker test_dash_node test_dash_share_messages test_dash_stratum_extranonce_split test_dash_stratum_submit_reassembly test_dash_difficulty_parity test_dash_auto_ratchet test_dash_min_protocol_gate test_dash_work_source test_dash_node_coin_state test_dash_coin_state_maintainer test_dash_node_embedded_wire test_dash_node_reception_wire test_dash_get_work \
                     test_hash_link test_decay_pplns \
                     test_pplns_consensus \
                     test_v36_script_sorting test_v36_cross_impl_refhash \

src/impl/dash/coinbase_builder.hpp

@@ -38,6 +38,7 @@
 #include "coin/transaction.hpp"
 #include "coin/rpc_data.hpp"
 #include "share_check.hpp"                 // decode_payee_script, pubkey_hash_to_script2, DONATION_SCRIPT
+#include "payout_muldiv.hpp"               // dash::payout::payout_share (MSVC-portable 128-bit muldiv)
 
 #include <algorithm>
 #include <cstdint>
@@ -126,16 +127,14 @@ inline std::vector<MinerPayout> compute_dash_payouts(
         core::version_gate::is_v36_active(params.current_share_version);
     std::map<Script, uint64_t> amounts;
     if (total_weight > 0) {
-        // weights/total_weight fit uint64 at the DASH layer; __uint128_t covers
-        // the products (worker_payout < 2^50, 49 < 2^6, weight < 2^64).
-        __uint128_t den = v36
-            ? static_cast<__uint128_t>(total_weight)
-            : static_cast<__uint128_t>(total_weight) * 50;
+        // weights/total_weight fit uint64 at the DASH layer, but the muldiv
+        // intermediate (worker_payout*weight*49 ~ 2^120, pre-v36 den > 2^64)
+        // needs a true 128-bit type. dash::payout::payout_share uses native
+        // __uint128_t on GCC/Clang and boost uint128 on MSVC (no __int128);
+        // the two are pinned bit-identical by test_dash_coinbase_muldiv.
         for (const auto& [script, w] : weights) {
-            __uint128_t num = static_cast<__uint128_t>(w)
-                            * static_cast<__uint128_t>(worker_payout);
-            if (!v36) num *= 49;
-            amounts[script] = static_cast<uint64_t>(num / den);
+            amounts[script] =
+                dash::payout::payout_share(w, worker_payout, total_weight, v36);
         }
     }
 

src/impl/dash/payout_muldiv.hpp

@@ -0,0 +1,85 @@
+#ifndef C2POOL_DASH_PAYOUT_MULDIV_HPP
+#define C2POOL_DASH_PAYOUT_MULDIV_HPP
+
+// ---------------------------------------------------------------------------
+// dash::payout -- MSVC-portable 128-bit intermediate for the PPLNS coinbase
+// payout proportion (coinbase_builder.hpp step 3-4).
+//
+// The per-script amount is a muldiv evaluated in a 128-bit intermediate:
+//
+//     v36     : amount = worker_payout * weight / total_weight
+//     pre-v36 : amount = worker_payout * 49 * weight / (total_weight * 50)
+//
+// The numerator worker_payout*weight*49 reaches ~2^120 (weight < 2^64,
+// worker_payout < 2^50, 49 < 2^6) and the pre-v36 denominator total_weight*50
+// exceeds 2^64, so a true 128-bit intermediate is REQUIRED.
+//
+// GCC/Clang provide native unsigned __int128 -- that path is kept BYTE-EXACT
+// for the shipping Linux/macOS c2pool-dash packages. MSVC has no __int128
+// (error C2065: '__uint128_t': undeclared identifier), which broke the
+// c2pool-dash Windows v0.2.1 build; on any compiler without __int128 we fall
+// back to boost::multiprecision::uint128_t, a fixed 128-bit unsigned type that
+// yields BIT-IDENTICAL results. This is CONSENSUS PAYOUT math -- a one-satoshi
+// divergence forks payouts -- so test_dash_coinbase_muldiv pins native ==
+// portable across the full DASH payout domain (the required guard). Mirrors the
+// BCH abla (#688) and DGB arith256 (#690) MSVC-portability rework.
+// ---------------------------------------------------------------------------
+
+#include <cassert>
+#include <cstdint>
+#include <limits>
+
+// Portable 128-bit intermediate on compilers without __int128 (MSVC).
+// Header-only; boost is already a c2pool dependency (conan + system libboost).
+#include <boost/multiprecision/cpp_int.hpp>
+
+namespace dash {
+namespace payout {
+
+// Portable path (MSVC and any non-__int128 compiler). Fixed 128-bit unsigned
+// boost intermediate -> BIT-IDENTICAL to the native __int128 result.
+inline uint64_t payout_share_portable(uint64_t weight, uint64_t worker_payout,
+                                      uint64_t total_weight, bool v36) {
+    assert(total_weight > 0);
+    using u128 = boost::multiprecision::uint128_t;
+    u128 num = u128(weight) * u128(worker_payout);
+    if (!v36) num *= 49u;
+    const u128 den = v36 ? u128(total_weight) : u128(total_weight) * 50u;
+    const u128 q = num / den;
+    assert(q <= u128(std::numeric_limits<uint64_t>::max()));
+    return static_cast<uint64_t>(q);
+}
+
+#if defined(__SIZEOF_INT128__)
+// Native path (GCC/Clang) -- BYTE-EXACT reproduction of the original
+// coinbase_builder.hpp:131-138 block; this is what the merged Linux/macOS
+// packages ship. Exposed by name so the KAT can diff it against the portable
+// path on the trusted platform.
+inline uint64_t payout_share_native(uint64_t weight, uint64_t worker_payout,
+                                    uint64_t total_weight, bool v36) {
+    assert(total_weight > 0);
+    const __uint128_t den = v36
+        ? static_cast<__uint128_t>(total_weight)
+        : static_cast<__uint128_t>(total_weight) * 50;
+    __uint128_t num = static_cast<__uint128_t>(weight)
+                    * static_cast<__uint128_t>(worker_payout);
+    if (!v36) num *= 49;
+    const __uint128_t q = num / den;
+    assert(q <= static_cast<__uint128_t>(std::numeric_limits<uint64_t>::max()));
+    return static_cast<uint64_t>(q);
+}
+inline uint64_t payout_share(uint64_t weight, uint64_t worker_payout,
+                             uint64_t total_weight, bool v36) {
+    return payout_share_native(weight, worker_payout, total_weight, v36);
+}
+#else
+inline uint64_t payout_share(uint64_t weight, uint64_t worker_payout,
+                             uint64_t total_weight, bool v36) {
+    return payout_share_portable(weight, worker_payout, total_weight, v36);
+}
+#endif
+
+} // namespace payout
+} // namespace dash
+
+#endif // C2POOL_DASH_PAYOUT_MULDIV_HPP

test/CMakeLists.txt

@@ -828,6 +828,19 @@ if (BUILD_TESTING AND GTest_FOUND)
     target_link_libraries(test_dash_coinbase_parity PRIVATE c2pool_payout c2pool_hashrate c2pool_merged_mining)  # OBJECT-lib SCC direct-naming (#22/#39)
     gtest_add_tests(test_dash_coinbase_parity "" AUTO)
 
+    # PPLNS coinbase payout muldiv: native(__int128) == portable(boost uint128)
+    # byte-parity -- MSVC-portability guard for coinbase_builder.hpp step 3-4
+    # (fixes c2pool-dash Windows v0.2.1 build). Pure header math; consensus.
+    add_executable(test_dash_coinbase_muldiv test_dash_coinbase_muldiv.cpp)
+    target_link_libraries(test_dash_coinbase_muldiv PRIVATE
+        GTest::gtest_main GTest::gtest
+        dash_x11 core
+        nlohmann_json::nlohmann_json
+        ${Boost_LIBRARIES}
+    )
+    target_link_libraries(test_dash_coinbase_muldiv PRIVATE c2pool_payout c2pool_hashrate c2pool_merged_mining)  # OBJECT-lib SCC direct-naming (#22/#39)
+    gtest_add_tests(test_dash_coinbase_muldiv "" AUTO)
+
     add_executable(test_dash_cb_payee test_dash_cb_payee.cpp)
     target_link_libraries(test_dash_cb_payee PRIVATE
         GTest::gtest_main GTest::gtest

test/test_dash_coinbase_muldiv.cpp

@@ -0,0 +1,137 @@
+// ---------------------------------------------------------------------------
+// dash::payout 128-bit payout muldiv KAT -- the guard for the MSVC-portability
+// rework of coinbase_builder.hpp (v0.2.1 c2pool-dash Windows build fix).
+//
+// coinbase_builder evaluates the PPLNS per-script coinbase amount in a 128-bit
+// intermediate:
+//     v36     : amount = worker_payout * weight / total_weight
+//     pre-v36 : amount = worker_payout * 49 * weight / (total_weight * 50)
+// GCC/Clang use native unsigned __int128; MSVC (no __int128, error C2065 on
+// '__uint128_t') falls back to boost::multiprecision::uint128_t. This is
+// CONSENSUS PAYOUT math -- a one-satoshi divergence forks payouts -- so the two
+// paths MUST be BIT-IDENTICAL.
+//
+// Two layers (mirrors bch abla muldiv_kat / dgb arith256_muldiv_kat):
+//   A. cross-platform known answers: payout_share() / payout_share_portable()
+//      produce exact fixed results on EVERY compiler incl. MSVC (all MSVC can
+//      run -- there is no native to diff against there). Several exercise a
+//      product > 2^64, which a 64-bit multiply would wrap and fail.
+//   B. Linux-only equivalence sweep (guarded by __SIZEOF_INT128__): the
+//      portable path must equal the native path across the DASH payout operand
+//      space plus a deterministic wide fuzz, over BOTH the v36 and pre-v36
+//      branches. Proving portable == native on the trusted platform certifies
+//      the MSVC path this CI cannot run.
+// ---------------------------------------------------------------------------
+
+#include <gtest/gtest.h>
+
+#include <cstdint>
+#include <limits>
+
+#include <impl/dash/payout_muldiv.hpp>
+
+namespace {
+
+using dash::payout::payout_share;
+using dash::payout::payout_share_portable;
+
+constexpr uint64_t U64MAX = std::numeric_limits<uint64_t>::max();
+
+// Deterministic 64-bit LCG (no <random>, no Date/rand) -- reproducible vectors.
+struct Lcg {
+    uint64_t s;
+    explicit Lcg(uint64_t seed) : s(seed) {}
+    uint64_t next() { s = s * 6364136223846793005ULL + 1442695040888963407ULL; return s; }
+};
+
+} // namespace
+
+// ---- A. cross-platform known answers (run on ALL compilers incl. MSVC) ------
+TEST(DashCoinbaseMuldiv, KnownAnswersV36) {
+    // v36: amount = worker_payout * weight / total_weight
+    EXPECT_EQ(payout_share(1, 100, 4, true), 25ULL);
+    EXPECT_EQ(payout_share(3, 100, 4, true), 75ULL);
+    EXPECT_EQ(payout_share(4, 100, 4, true), 100ULL);   // whole weight -> full payout
+    EXPECT_EQ(payout_share(0, 100, 4, true), 0ULL);
+    // product > 2^64 (weight*worker_payout = 2^80): a 64-bit multiply would wrap.
+    EXPECT_EQ(payout_share(1099511627776ULL, 1099511627776ULL,
+                           1099511627776ULL, true), 1099511627776ULL);
+}
+
+TEST(DashCoinbaseMuldiv, KnownAnswersPreV36) {
+    // pre-v36: amount = worker_payout * 49 * weight / (total_weight * 50)
+    EXPECT_EQ(payout_share(50, 100, 50, false), 98ULL);  // whole share = 98% (2% finder fee added separately)
+    EXPECT_EQ(payout_share(1, 100, 2, false), 49ULL);
+    EXPECT_EQ(payout_share(0, 100, 50, false), 0ULL);
+    // numerator worker_payout*49*weight ~ 2^75 (> 2^64) and den = total*50 > 2^64.
+    EXPECT_EQ(payout_share(1099511627776ULL, 1000000ULL,
+                           1099511627776ULL, false), 980000ULL);
+}
+
+TEST(DashCoinbaseMuldiv, PortablePathSatisfiesKnownAnswers) {
+    // the MSVC fallback must independently produce the same answers.
+    EXPECT_EQ(payout_share_portable(1, 100, 4, true), 25ULL);
+    EXPECT_EQ(payout_share_portable(4, 100, 4, true), 100ULL);
+    EXPECT_EQ(payout_share_portable(1099511627776ULL, 1099511627776ULL,
+                                    1099511627776ULL, true), 1099511627776ULL);
+    EXPECT_EQ(payout_share_portable(50, 100, 50, false), 98ULL);
+    EXPECT_EQ(payout_share_portable(1099511627776ULL, 1000000ULL,
+                                    1099511627776ULL, false), 980000ULL);
+}
+
+#if defined(__SIZEOF_INT128__)
+// ---- B. native == portable across the DASH payout domain (trusted platform) -
+TEST(DashCoinbaseMuldiv, NativeEqualsPortableGrid) {
+    using dash::payout::payout_share_native;
+    // operand shapes from the coinbase_builder call site: weights are subsets of
+    // total_weight (so quotient <= worker_payout), worker_payout < 2^50.
+    const uint64_t totals[] = {
+        1, 2, 50, 100, 37938, 1000000ULL,
+        (1ULL << 30), (1ULL << 40), (1ULL << 62), U64MAX
+    };
+    const uint64_t payouts[] = {
+        0, 1, 100, 5000000000ULL, (1ULL << 40), (1ULL << 50) - 1
+    };
+    for (uint64_t total : totals) {
+        // weight sampled across [0, total]: 0, 1, total/2, total-1, total.
+        const uint64_t weights[] = {
+            0, 1, total / 2, total > 0 ? total - 1 : 0, total
+        };
+        for (uint64_t w : weights)
+            for (uint64_t wp : payouts)
+                for (bool v36 : {false, true}) {
+                    EXPECT_EQ(payout_share_native(w, wp, total, v36),
+                              payout_share_portable(w, wp, total, v36))
+                        << "w=" << w << " wp=" << wp
+                        << " total=" << total << " v36=" << v36;
+                }
+    }
+}
+
+TEST(DashCoinbaseMuldiv, NativeEqualsPortableFuzz) {
+    using dash::payout::payout_share_native;
+    Lcg rng(0x9E3779B97F4A7C15ULL);
+    int compared = 0;
+    for (int i = 0; i < 200000; ++i) {
+        uint64_t total = rng.next();
+        if (total == 0) total = 1;
+        const uint64_t w  = rng.next() % total;                 // weight in [0, total)
+        const uint64_t wp = rng.next() & ((1ULL << 50) - 1);    // worker_payout < 2^50
+        const bool v36 = (rng.next() & 1) != 0;
+        ++compared;
+        ASSERT_EQ(payout_share_native(w, wp, total, v36),
+                  payout_share_portable(w, wp, total, v36))
+            << "fuzz i=" << i << " w=" << w << " wp=" << wp
+            << " total=" << total << " v36=" << v36;
+    }
+    EXPECT_GT(compared, 1000);
+    std::cerr << "dash coinbase muldiv KAT: native==portable over "
+              << compared << " fuzz vectors\n";
+}
+#else
+TEST(DashCoinbaseMuldiv, NoInt128KnownAnswerLayerOnly) {
+    std::cerr << "dash coinbase muldiv KAT: no __int128 (MSVC) -- "
+                 "known-answer layer only\n";
+    SUCCEED();
+}
+#endif