Implement electrum transaction.id_from_pos.

include/bitcoin/server/interfaces/electrum.hpp

@@ -46,7 +46,7 @@ struct electrum_methods
         method<"blockchain.transaction.broadcast", string_t>{ "raw_tx" },
         method<"blockchain.transaction.get", string_t, boolean_t>{ "tx_hash", "verbose" },
         method<"blockchain.transaction.get_merkle", string_t, number_t>{ "tx_hash", "height" },
-        method<"blockchain.transaction.id_from_pos", number_t, number_t, boolean_t>{ "height", "tx_pos", "merkle" },
+        method<"blockchain.transaction.id_from_pos", number_t, number_t, optional<false>>{ "height", "tx_pos", "merkle" },
 
         /// Server methods.
         method<"server.add_peer", object_t>{ "features" },

src/protocols/protocol_electrum.cpp

@@ -270,7 +270,7 @@ void protocol_electrum::blockchain_block_headers(size_t starting,
 
         array_t branch(proof.size());
         std::ranges::transform(proof, branch.begin(),
-            [](const auto& hash) { return encode_hash(hash); });
+            [](const auto& hash) NOEXCEPT { return encode_hash(hash); });
 
         result["branch"] = std::move(branch);
         result["root"] = encode_hash(root);
@@ -526,11 +526,73 @@ void protocol_electrum::handle_blockchain_transaction_get_merkle(const code& ec,
 }
 
 void protocol_electrum::handle_blockchain_transaction_id_from_pos(const code& ec,
-    rpc_interface::blockchain_transaction_id_from_pos, double ,
-    double , bool ) NOEXCEPT
+    rpc_interface::blockchain_transaction_id_from_pos, double height,
+    double tx_pos, bool merkle) NOEXCEPT
 {
-    if (stopped(ec)) return;
-    send_code(error::not_implemented);
+    if (stopped(ec))
+        return;
+
+    size_t position{};
+    size_t block_height{};
+    if (!to_integer(block_height, height) ||
+        !to_integer(position, tx_pos))
+    {
+        send_code(error::invalid_argument);
+        return;
+    }
+
+    const auto& query = archive();
+    const auto block_link = query.to_confirmed(block_height);
+    const auto tx_link = query.get_position_tx(block_link, position);
+    if (tx_link.is_terminal())
+    {
+        send_code(error::not_found);
+        return;
+    }
+
+    using namespace system;
+    const auto hash = query.get_tx_key(tx_link);
+    if (hash == null_hash)
+    {
+        send_code(error::server_error);
+        return;
+    }
+
+    if (!merkle)
+    {
+        send_result(encode_hash(hash), two * hash_size, BIND(complete, _1));
+    }
+    else
+    {
+        auto hashes = query.get_tx_keys(block_link);
+        if (hashes.empty())
+        {
+            send_code(error::server_error);
+            return;
+        }
+
+        if (position >= hashes.size())
+        {
+            send_code(error::not_found);
+            return;
+        }
+
+        using namespace chain;
+        const auto proof = block::merkle_branch(position, std::move(hashes));
+
+        array_t branch(proof.size());
+        std::ranges::transform(proof, branch.begin(),
+            [](const auto& hash) NOEXCEPT { return encode_hash(hash); });
+
+        send_result(
+        {
+            object_t
+            {
+                { "tx_hash", encode_hash(hash) },
+                { "merkle", std::move(branch) }
+            }
+        }, two * hash_size * add1(branch.size()), BIND(complete, _1));
+    }
 }
 
 // Handlers (server).

test/protocols/electrum/electrum_transactions.cpp

@@ -98,9 +98,9 @@ BOOST_AUTO_TEST_CASE(electrum__blockchain_transaction_get__missing_param__droppe
     BOOST_CHECK(handshake());
 
     const auto& coinbase = *genesis.transactions_ptr()->front();
-    const auto tx_hash = encode_hash(coinbase.hash(false));
+    const auto tx0_hash = encode_hash(coinbase.hash(false));
     const auto request = R"({"id":80,"method":"blockchain.transaction.get","params":["%1%"]})" "\n";
-    const auto response = get((boost::format(request) % tx_hash).str());
+    const auto response = get((boost::format(request) % tx0_hash).str());
     BOOST_CHECK(response.at("dropped").as_bool());
 }
 
@@ -109,9 +109,9 @@ BOOST_AUTO_TEST_CASE(electrum__blockchain_transaction_get__extra_param__dropped)
     BOOST_CHECK(handshake());
 
     const auto& coinbase = *genesis.transactions_ptr()->front();
-    const auto tx_hash = encode_hash(coinbase.hash(false));
+    const auto tx0_hash = encode_hash(coinbase.hash(false));
     const auto request = R"({"id":81,"method":"blockchain.transaction.get","params":["%1%",false,"extra"]})" "\n";
-    const auto response = get((boost::format(request) % tx_hash).str());
+    const auto response = get((boost::format(request) % tx0_hash).str());
     BOOST_CHECK(response.at("dropped").as_bool());
 }
 
@@ -120,9 +120,9 @@ BOOST_AUTO_TEST_CASE(electrum__blockchain_transaction_get__genesis_coinbase_verb
     BOOST_CHECK(handshake());
 
     const auto& coinbase = *genesis.transactions_ptr()->front();
-    const auto tx_hash = encode_hash(coinbase.hash(false));
+    const auto tx0_hash = encode_hash(coinbase.hash(false));
     const auto request = R"({"id":82,"method":"blockchain.transaction.get","params":["%1%",false]})" "\n";
-    const auto response = get((boost::format(request) % tx_hash).str());
+    const auto response = get((boost::format(request) % tx0_hash).str());
     BOOST_CHECK_EQUAL(response.at("result").as_string(), encode_base16(coinbase.to_data(true)));
 }
 
@@ -131,9 +131,9 @@ BOOST_AUTO_TEST_CASE(electrum__blockchain_transaction_get__genesis_coinbase_verb
     BOOST_CHECK(handshake());
 
     const auto& coinbase = *genesis.transactions_ptr()->front();
-    const auto tx_hash = encode_hash(coinbase.hash(false));
+    const auto tx0_hash = encode_hash(coinbase.hash(false));
     const auto request = R"({"id":83,"method":"blockchain.transaction.get","params":["%1%",true]})" "\n";
-    const auto response = get((boost::format(request) % tx_hash).str());
+    const auto response = get((boost::format(request) % tx0_hash).str());
 
     auto expected = value_from(bitcoind(coinbase));
     BOOST_CHECK(expected.is_object());
@@ -150,6 +150,57 @@ BOOST_AUTO_TEST_CASE(electrum__blockchain_transaction_get__genesis_coinbase_verb
 }
 
 // blockchain.transaction.get_merkle
+
 // blockchain.transaction.id_from_pos
 
+BOOST_AUTO_TEST_CASE(electrum__blockchain_transaction_id_from_pos__genesis_coinbase_default__expected)
+{
+    BOOST_CHECK(handshake());
+
+    const auto& coinbase = *genesis.transactions_ptr()->front();
+    const auto tx0_hash = encode_hash(coinbase.hash(false));
+    const auto request = R"({"id":90,"method":"blockchain.transaction.id_from_pos","params":[0,0]})" "\n";
+    const auto response = get(request);
+    BOOST_CHECK_EQUAL(response.at("result").as_string(), tx0_hash);
+}
+
+BOOST_AUTO_TEST_CASE(electrum__blockchain_transaction_id_from_pos__coinbase_false__expected)
+{
+    BOOST_CHECK(handshake());
+
+    const auto& coinbase = *block2.transactions_ptr()->front();
+    const auto tx0_hash = encode_hash(coinbase.hash(false));
+    const auto request = R"({"id":91,"method":"blockchain.transaction.id_from_pos","params":[2,0,false]})" "\n";
+    const auto response = get(request);
+    BOOST_CHECK_EQUAL(response.at("result").as_string(), tx0_hash);
+}
+
+BOOST_AUTO_TEST_CASE(electrum__blockchain_transaction_id_from_pos__merkle_proof_one_tx__empty)
+{
+    BOOST_CHECK(handshake());
+
+    const auto& coinbase = *block9.transactions_ptr()->front();
+    const auto tx0_hash = encode_hash(coinbase.hash(false));
+    const auto request = R"({"id":92,"method":"blockchain.transaction.id_from_pos","params":[9,0,true]})" "\n";
+    const auto& object = get(request).at("result").as_object();
+    BOOST_CHECK_EQUAL(object.at("tx_hash").as_string(), tx0_hash);
+    BOOST_CHECK(object.at("merkle").as_array().empty());
+}
+
+BOOST_AUTO_TEST_CASE(electrum__blockchain_transaction_id_from_pos__missing_block__not_found)
+{
+    BOOST_CHECK(handshake());
+
+    const auto request = R"({"id":93,"method":"blockchain.transaction.id_from_pos","params":[11,0]})" "\n";
+    BOOST_CHECK_EQUAL(get(request).at("error").as_object().at("code").as_int64(), not_found.value());
+}
+
+BOOST_AUTO_TEST_CASE(electrum__blockchain_transaction_id_from_pos__missing_position__not_found)
+{
+    BOOST_CHECK(handshake());
+
+    const auto request = R"({"id":94,"method":"blockchain.transaction.id_from_pos","params":[0,1]})" "\n";
+    BOOST_CHECK_EQUAL(get(request).at("error").as_object().at("code").as_int64(), not_found.value());
+}
+
 BOOST_AUTO_TEST_SUITE_END()