Fix merge_merkle().

Author: evoskuil

include/bitcoin/database/impl/query/merkle.ipp

@@ -20,6 +20,7 @@
 #define LIBBITCOIN_DATABASE_QUERY_MERKLE_IPP
 
 #include <algorithm>
+#include <iterator>
 #include <ranges>
 #include <utility>
 #include <bitcoin/database/define.hpp>
@@ -77,17 +78,18 @@ CLASS::hash_option CLASS::get_confirmed_interval(size_t height) const NOEXCEPT
 TEMPLATE
 void CLASS::merge_merkle(hashes& to, hashes&& from, size_t first) NOEXCEPT
 {
-    // from is either even or has one additional element of reserved space.
+    // From is either even or has one additional element of reserved space.
     if (!is_one(from.size()) && is_odd(from.size()))
         from.push_back(from.back());
 
-    using namespace system;
     for (const auto& row: block::merkle_branch(first, from.size()))
     {
-        BC_ASSERT(add1(row.sibling) * row.width <= from.size());
-        const auto it = std::next(from.begin(), row.sibling * row.width);
-        const auto mover = std::make_move_iterator(it);
-        to.push_back(merkle_root({ mover, std::next(mover, row.width) }));
+        if (const auto start = row.sibling * row.width; start < from.size())
+        {
+            const auto count = std::min(row.width, from.size() - start);
+            auto it = std::make_move_iterator(std::next(from.begin(), start));
+            to.push_back(partial_subroot({ it, std::next(it, count) }, row.width));
+        }
     }
 }
 

test/query/merkle.cpp

@@ -408,10 +408,8 @@ BOOST_AUTO_TEST_CASE(query_merkle__get_merkle_subroots__waypoint_zero__genesis)
     BOOST_CHECK_EQUAL(query.get_merkle_subroots(roots, 0), error::success);
     BOOST_CHECK_EQUAL(roots.size(), 1u);
 
-    // At depth 2, 1 hash must be elevated twice, and paired twice.
-    constexpr auto root00 = system::sha256::double_hash(test::block0_hash, test::block0_hash);
-    constexpr auto root0000 = system::sha256::double_hash(root00, root00);
-    BOOST_CHECK_EQUAL(roots[0], root0000);
+    // At depth 2, the 1st position (block 0) the hash is the root.
+    BOOST_CHECK_EQUAL(roots[0], test::block0_hash);
 }
 
 BOOST_AUTO_TEST_CASE(query_merkle__get_merkle_subroots__one_full_interval__expected_root)
@@ -434,7 +432,7 @@ BOOST_AUTO_TEST_CASE(query_merkle__get_merkle_subroots__one_full_interval__expec
     BOOST_CHECK_EQUAL(query.get_merkle_subroots(roots, 3), error::success);
     BOOST_CHECK_EQUAL(roots.size(), 1u);
 
-    // At depth 2, the 4th position (block 3) results in a simple root.
+    // At depth 2, the 4th position (block 3) results in an interval subroot as the root.
     BOOST_CHECK_EQUAL(roots[0], root03);
 }
 
@@ -573,7 +571,7 @@ BOOST_AUTO_TEST_CASE(query_merkle__get_merkle_root_and_proof__electrumx_example_
     BOOST_CHECK_EQUAL(proof[0], test::block4_hash);
     BOOST_CHECK_EQUAL(proof[1], sub67);
     BOOST_CHECK_EQUAL(proof[2], sub03);
-    BOOST_CHECK_EQUAL(proof[3], sub88);
+    BOOST_CHECK_EQUAL(proof[3], sub88); // << FAIL
 }
 
 BOOST_AUTO_TEST_CASE(query_merkle__get_merkle_root_and_proof__electrumx_example_depth_1__success)
@@ -621,7 +619,7 @@ BOOST_AUTO_TEST_CASE(query_merkle__get_merkle_root_and_proof__electrumx_example_
     BOOST_CHECK_EQUAL(proof[0], test::block4_hash);
     BOOST_CHECK_EQUAL(proof[1], sub67);
     BOOST_CHECK_EQUAL(proof[2], sub03);
-    BOOST_CHECK_EQUAL(proof[3], sub88);
+    BOOST_CHECK_EQUAL(proof[3], sub88); // << FAIL
 }
 
 BOOST_AUTO_TEST_CASE(query_merkle__get_merkle_root_and_proof__electrumx_example_depth_2__success)
@@ -756,7 +754,7 @@ BOOST_AUTO_TEST_CASE(query_merkle__get_merkle_root_and_proof__electrumx_example_
     BOOST_CHECK_EQUAL(proof[0], test::block4_hash);
     BOOST_CHECK_EQUAL(proof[1], sub67);
     BOOST_CHECK_EQUAL(proof[2], sub03);
-    BOOST_CHECK_EQUAL(proof[3], sub88);
+    BOOST_CHECK_EQUAL(proof[3], sub88); // << FAIL
 }
 
 BOOST_AUTO_TEST_CASE(query_merkle__get_merkle_root_and_proof__electrumx_example_depth_11__success)
@@ -800,7 +798,7 @@ BOOST_AUTO_TEST_CASE(query_merkle__get_merkle_root_and_proof__electrumx_example_
     BOOST_CHECK_EQUAL(proof[0], test::block4_hash);
     BOOST_CHECK_EQUAL(proof[1], sub67);
     BOOST_CHECK_EQUAL(proof[2], sub03);
-    BOOST_CHECK_EQUAL(proof[3], sub88);
+    BOOST_CHECK_EQUAL(proof[3], sub88); // << FAIL
 }
 
 BOOST_AUTO_TEST_CASE(query_merkle__get_merkle_root_and_proof__target_greater_than_waypoint__error_invalid_argument)