btc/v36: network-id/prefix independence (#95 BTC mirror)

.github/workflows/build.yml

@@ -67,6 +67,7 @@ jobs:
                     test_mweb_builder \
                     test_address_resolution test_compute_share_target \
                     test_utxo \
+                    v37_test \
             -j$(nproc)
 
       - name: Run tests
@@ -192,6 +193,7 @@ jobs:
                     test_address_resolution test_compute_share_target \
                     test_utxo \
                     test_coin_broadcaster test_multiaddress_pplns test_pplns_stress \
+                    v37_test \
             -j$(nproc)
 
       - name: Run tests under sanitizers

src/c2pool/main_btc.cpp

@@ -83,7 +83,13 @@ static void print_usage()
         "  --stratum [H:]P stratum TCP listener for miners (B4-stratum)\n"
         "                  e.g. --stratum 9332           (binds 0.0.0.0:9332)\n"
         "                       --stratum 127.0.0.1:9332 (loopback only)\n"
-        "                  Omit to disable stratum listener.\n";
+        "                  Omit to disable stratum listener.\n"
+        "  --network-id ID c2pool sharechain IDENTIFIER (hex, <=8 bytes) for a\n"
+        "                  private/custom p2pool network. Omit for public BTC.\n"
+        "  --prefix HEX    c2pool sharechain PREFIX (hex, <=8 bytes), an\n"
+        "                  INDEPENDENT per-network constant (no algebraic tie to\n"
+        "                  IDENTIFIER). Supply with --network-id to join a custom\n"
+        "                  p2pool chain; omit to use the compiled default prefix.\n";
 }
 
 /// BTC wire-protocol magic bytes per network (pchMessageStart).
@@ -109,6 +115,8 @@ int main(int argc, char* argv[])
     uint16_t    p2pool_port   = 0;
     std::string stratum_addr  = "0.0.0.0";  // listen all interfaces by default
     uint16_t    stratum_port  = 0;          // 0 disables stratum; --stratum sets it
+    std::string network_id_hex;             // --network-id: c2pool IDENTIFIER override (empty = public net)
+    std::string prefix_hex;                 // --prefix: c2pool PREFIX override (empty = compiled default)
 
     for (int i = 1; i < argc; ++i)
     {
@@ -165,6 +173,14 @@ int main(int argc, char* argv[])
                 stratum_port = static_cast<uint16_t>(std::stoi(ep.substr(colon + 1)));
             }
         }
+        else if (arg == "--network-id" && i + 1 < argc)
+        {
+            network_id_hex = argv[++i];
+        }
+        else if (arg == "--prefix" && i + 1 < argc)
+        {
+            prefix_hex = argv[++i];
+        }
         else
         {
             std::cerr << "unknown arg: " << arg << "\n";
@@ -181,6 +197,14 @@ int main(int argc, char* argv[])
 
     btc::PoolConfig::is_testnet = testnet;
 
+    // B2-net: apply optional private-chain overrides. IDENTIFIER and PREFIX are
+    // two INDEPENDENT per-network constants — set_network_id never derives one
+    // from the other (commit 9034b59d). A bare --network-id keeps the compiled
+    // network-default prefix; supply --prefix to join a custom p2pool chain.
+    if (!prefix_hex.empty() && network_id_hex.empty())
+        std::cerr << "[BTC] warning: --prefix ignored without --network-id\n";
+    btc::PoolConfig::set_network_id(network_id_hex, prefix_hex);
+
     auto chain_params = testnet4
         ? btc::coin::BTCChainParams::testnet4()
         : (testnet ? btc::coin::BTCChainParams::testnet()

src/impl/btc/config_pool.hpp

@@ -157,33 +157,35 @@ class PoolConfig : protected core::Fileconfig
     static inline std::string override_identifier_hex;
     static inline std::string override_prefix_hex;
 
-    /// Set private network identity. IDENTIFIER is the consensus secret
-    /// (hashed into ref_hash). PREFIX is derived from it for transport framing.
-    /// Call once at startup before any P2P or share operations.
-    static void set_network_id(const std::string& network_id_hex) {
+    /// Set private network identity. IDENTIFIER and PREFIX are TWO INDEPENDENT
+    /// per-network constants (p2pool model) — there is NO algebraic relationship
+    /// between them, so PREFIX is never derived from IDENTIFIER. To join a custom
+    /// p2pool sharechain, supply BOTH the network id and its prefix (each a
+    /// separate per-network constant). If the prefix override is omitted, the
+    /// compiled network-default prefix is used. Call once at startup before any
+    /// P2P or share operations.
+    static void set_network_id(const std::string& network_id_hex,
+                               const std::string& prefix_hex_override = "") {
         if (network_id_hex.empty() || network_id_hex == "0" || network_id_hex == "00000000")
             return;  // public network, use defaults
 
-        // Pad to 16 hex chars (8 bytes) if shorter
-        std::string padded = network_id_hex;
-        while (padded.size() < 16) padded = "0" + padded;
-        if (padded.size() > 16) padded = padded.substr(0, 16);
-
-        override_identifier_hex = padded;
-
-        // Derive PREFIX from IDENTIFIER using simple XOR mixing
-        // PREFIX = IDENTIFIER bytes XOR-rotated (fast, deterministic, non-reversible enough
-        // for transport framing — the real security is in IDENTIFIER via ref_hash)
-        auto id_bytes = ParseHex(padded);
-        static const char* HEX = "0123456789abcdef";
-        override_prefix_hex.clear();
-        override_prefix_hex.reserve(16);
-        for (size_t i = 0; i < 8 && i < id_bytes.size(); ++i) {
-            // XOR with rotated byte + constant to ensure PREFIX != IDENTIFIER
-            uint8_t b = id_bytes[i] ^ id_bytes[(i + 3) % id_bytes.size()] ^ 0x5A;
-            override_prefix_hex += HEX[b >> 4];
-            override_prefix_hex += HEX[b & 0x0f];
-        }
+        // Normalize a hex string to exactly 16 hex chars (8 bytes).
+        auto to8 = [](std::string h) {
+            while (h.size() < 16) h = "0" + h;
+            if (h.size() > 16) h = h.substr(0, 16);
+            return h;
+        };
+
+        override_identifier_hex = to8(network_id_hex);
+
+        // PREFIX is an INDEPENDENT transport constant — set it directly from the
+        // override and NEVER derive it from IDENTIFIER. The old XOR-rotate
+        // derivation has no p2pool analog and structurally prevented c2pool from
+        // joining any p2pool custom network (derived prefix != p2pool prefix).
+        // When no prefix override is given, leave override_prefix_hex empty so
+        // prefix_hex() falls back to the compiled network default.
+        if (!prefix_hex_override.empty())
+            override_prefix_hex = to8(prefix_hex_override);
     }
 
     static const std::string& identifier_hex() {
@@ -207,8 +209,8 @@ class PoolConfig : protected core::Fileconfig
         if (override_identifier_hex.empty())
             return 0;  // public network
 
-        auto pfx_bytes = ParseHex(override_prefix_hex);
-        auto id_bytes = ParseHex(override_identifier_hex);
+        auto pfx_bytes = ParseHex(prefix_hex());
+        auto id_bytes = ParseHex(identifier_hex());
         std::vector<unsigned char> preimage;
         preimage.reserve(pfx_bytes.size() + id_bytes.size());
         preimage.insert(preimage.end(), pfx_bytes.begin(), pfx_bytes.end());

src/sharechain/CMakeLists.txt

@@ -11,4 +11,5 @@ set(SHARECHAIN_SOURCE
 add_library(sharechain OBJECT ${SHARECHAIN_SOURCE})
 target_link_libraries(sharechain core)
 
-add_subdirectory(test)
+add_subdirectory(test)
+add_subdirectory(v37/test)

src/sharechain/v37/IMPLEMENTATION-NOTES.md

@@ -0,0 +1,99 @@
+# V37 MRR Roundabout Round-Buffer — implementation notes (WIP for review)
+
+Branch: `v37/mrr-roundabout-buffer`. Spec: `c2pool-v37-mrr-roundabout-buffer.md` v1.0
+(all OQ/S decisions resolved). Module: `src/sharechain/v37/`, header-only,
+`namespace v37`, stdlib-only — compiles and tests standalone with
+`g++ -std=c++20`, no conan/boost/btclibs dependency.
+
+## Done (implemented + tested on this VM)
+
+| Component (brief) | Where | Status |
+|---|---|---|
+| 1. Lane storage, bucket leaves (F-1 fields) | `v37_lane.hpp` | done |
+| 2. MRR roll-up pyramid (OQ-5 geometry) | `v37_lane.hpp` (`fold_l0`, `cascade_folds`) | done; L=2 default fully tested, L≥3 see notes |
+| 3. Epoch-scaled incremental decay + OQ-2 exact rebuild | `v37_lane.hpp` (`push`, `epoch_rebuild`) | done |
+| 4. PayoutDescriptor v1 (OQ-3, S-1/S-2/S-3) | `v37_descriptor.hpp` | done |
+| 5. Quantized window (OQ-1) + reorg journal D=64 (OQ-7) | `v37_lane.hpp` (`evict_oldest_bucket`, `rewind`) | done |
+| 6. Lane digest (§8.5, OQ-4) | `v37_lane.hpp` (`digest`) | done |
+| 7. Fixed-point model + slow reference + bit-exact gate | `v37_fixed.hpp` + `test/v37_test.cpp` (`ReferenceLane`) | done |
+| Multichain container + miner intern | `v37_roundabout.hpp` | done |
+
+Test run (g++ 13.3, -O2 and again under `-fsanitize=address,undefined`):
+**100,338 checks, 0 failures.** The consensus gate is `ReferenceLane` — an
+independent implementation whose per-miner weights are recomputed by full
+scan of the durable records after EVERY push — compared bit-exact against the
+incremental accumulators, across two geometries (small stress geometry, 5+
+epochs; ratified OQ-5 default geometry across two epoch rebuilds, ~9.5k
+pushes, full-u64-range weights). Also covered: digest determinism +
+sensitivity, rewind bit-exact restoration, window quantization, raw-work
+conservation (F-1), descriptor canon vectors for all five template kinds +
+kind-255 fallback, S-1 identity distinctness, aux/attribution validity rules,
+runtime lane add/remove, cross-lane identity intern.
+
+## Range pinning + spec errata (flag for the spec's next revision)
+
+1. **Q62, not Q64.** §8.2 says "widens to 64 fractional bits"; §8.1 delegates
+   exact range pinning here. Pinned at FRAC_BITS = 62 so that: every table
+   entry (decay ≤ 1.0, inverse ≤ 2^1.9) fits u64; w_raw keeps the FULL u64
+   range; every w_raw × table product fits native unsigned __int128;
+   accumulators fit 256 bits. Still 2^22 finer than V36's Q40. Suggest spec
+   erratum: "62 fractional bits" with this rationale.
+2. **Wider storage than the §3 struct sketch.** Spec sketches comp w_scaled
+   as q64 and bucket scaled_sum as q128; with full-range u64 raw work those
+   overflow. Implementation uses u128 (L0 scaled) and U256 (sums, comp
+   scaled). Spec §5 footprint numbers shift accordingly; tightening back
+   down requires capping w_raw (a consensus parameter decision — operator).
+3. **Journal does not cross epoch rebuilds.** `rewind()` refuses if the span
+   crosses a rebuild (journal is cleared there); caller takes the full lane
+   rebuild path — the same escape hatch as the >D case (§6.2). Affects ~D/E
+   ≈ 1.6% of max-depth reorgs at default geometry. Suggest folding this rule
+   into §6.2 explicitly.
+4. **Level sums for levels ≥ 1.** Buckets in one level can carry different
+   epoch tags (immutability rule), so a single stored per-level scaled sum is
+   frame-mixed; the per-band view weight is assembled per-bucket with the
+   epoch shift (O(buckets/level) ≤ 568) instead of a maintained O(1) field.
+   L0 sums are maintained O(1) as specced.
+5. **No residual dust at L = 2 (stronger than spec).** §4.2 tolerates
+   deterministic truncation residuals between rebuilds; with the
+   rebuild-from-raw design and default L = 2 the incremental state equals the
+   full-scan reference EXACTLY at every operation (proven by the gate). The
+   only residual source is the L≥3 cascade fold (children re-framed at fold);
+   at L≥3 the gate holds at rebuild points, per spec. L≥3 needs its own
+   rebuild-point-gated test before any chain uses it.
+
+## Stubbed / deferred (not blocking review)
+
+- **L1 view projection** (`RingFrame`/`Level` serialization for
+  `/pplns/rings`): not implemented — view-layer concern; all backing queries
+  exist (`payout_map`, `raw_work_in_span`, `levels()` accessor, digest).
+- **SoA / arena / power-of-two mask storage**: test-grade impl uses
+  std::deque/std::vector with identical semantics; the §5 memory-layout
+  optimizations (contiguous SoA rings, bump-allocated comps, SIMD renorm
+  pass) are an integration-phase change that cannot alter results (same op
+  sequence, same arithmetic).
+- **THE state-root hookup**: `Lane::digest()` produces the leaf; committing
+  it into the coinbase OP_RETURN root is wiring in the existing THE
+  commitment path, out of scope for the standalone module.
+- **Adaptive W (OQ-6)**: headroom only, per the resolution — W is a
+  LaneParams constant; no formula.
+
+## Needs CI / integrator attention
+
+1. **Weight adapter**: V36 `att` is `uint288` (`target_to_average_attempts`).
+   The lane takes `w_raw : u64`. For sharechain share targets this fits
+   easily (att ≈ share_difficulty × 2^32), but the adapter MUST assert/clamp
+   att ≤ u64::max — define the rule (reject share vs clamp) as a consensus
+   parameter before wiring. Flagged rather than decided here.
+2. **Hashers**: `v37_hash.hpp` is a self-contained FIPS-conformant SHA-256
+   (known-vector tested, bit-equal to core's CSHA256). Integration may swap
+   to `core/hash.hpp` for one less implementation; output identical.
+3. **Full-tree build**: `src/sharechain/CMakeLists.txt` gained
+   `add_subdirectory(v37/test)`; the test target is dependency-free and
+   gated on BUILD_TESTING. Not exercised against the full conan build on
+   this VM (by design) — ci-steward/btc-heap-opt to verify.
+4. **gtest port**: the suite uses a standalone CHECK harness so it runs
+   without GTest; trivially portable to the repo's gtest idiom if preferred.
+5. **Caller migration**: `HeadPPLNS`/`think()` integration (replacing
+   `DensePPLNSRing` per the spec's "subsumes" map) is intentionally not
+   started — the module is per-coin-agnostic and caller-shaped for it
+   (push/rewind/payout_map mirror slide/rebuild/compute_v36_weights).

src/sharechain/v37/test/CMakeLists.txt

@@ -0,0 +1,9 @@
+# V37 MRR roundabout — standalone unit tests.
+# Header-only module, stdlib-only: no gtest, no core link needed. The suite
+# is its own harness (returns nonzero on failure) so it runs anywhere the
+# toolchain exists, including outside the conan/boost dependency tree.
+if (BUILD_TESTING)
+    add_executable(v37_test v37_test.cpp)
+    target_compile_features(v37_test PRIVATE cxx_std_20)
+    add_test(NAME v37_test COMMAND v37_test)
+endif()