Implement some electrum interface methods.

Author: evoskuil

include/bitcoin/server/interfaces/electrum.hpp

@@ -35,7 +35,7 @@ struct electrum_methods
         method<"blockchain.block.header", number_t, number_t>{ "height", "cp_height" },
         method<"blockchain.block.headers", number_t, number_t, number_t>{ "start_height", "count", "cp_height" },
         method<"blockchain.headers.subscribe">{},
-        method<"blockchain.estimatefee", number_t>{ "number" },
+        method<"blockchain.estimatefee", number_t, optional<""_t>>{ "number", "mode" },
         method<"blockchain.relayfee">{},
         method<"blockchain.scripthash.get_balance", string_t>{ "scripthash" },
         method<"blockchain.scripthash.get_history", string_t>{ "scripthash" },
@@ -71,8 +71,8 @@ struct electrum_methods
     using blockchain_block_header = at<0>;
     using blockchain_block_headers = at<1>;
     using blockchain_headers_subscribe = at<2>;
-    using blockchain_estimatefee = at<3>;
-    using blockchain_relayfee = at<4>;
+    using blockchain_estimate_fee = at<3>;
+    using blockchain_relay_fee = at<4>;
     using blockchain_scripthash_get_balance = at<5>;
     using blockchain_scripthash_get_history = at<6>;
     using blockchain_scripthash_get_mempool = at<7>;

include/bitcoin/server/protocols/protocol_electrum.hpp

@@ -59,10 +59,11 @@ class BCS_API protocol_electrum
         double count, double cp_height) NOEXCEPT;
     void handle_blockchain_headers_subscribe(const code& ec,
         rpc_interface::blockchain_headers_subscribe) NOEXCEPT;
-    void handle_blockchain_estimatefee(const code& ec,
-        rpc_interface::blockchain_estimatefee, double) NOEXCEPT;
-    void handle_blockchain_relayfee(const code& ec,
-        rpc_interface::blockchain_relayfee) NOEXCEPT;
+    void handle_blockchain_estimate_fee(const code& ec,
+        rpc_interface::blockchain_estimate_fee, double number,
+        const std::string& mode) NOEXCEPT;
+    void handle_blockchain_relay_fee(const code& ec,
+        rpc_interface::blockchain_relay_fee) NOEXCEPT;
     void handle_blockchain_scripthash_get_balance(const code& ec,
         rpc_interface::blockchain_scripthash_get_balance,
         const std::string& scripthash) NOEXCEPT;

src/protocols/protocol_electrum.cpp

@@ -29,6 +29,7 @@ namespace server {
 
 #define CLASS protocol_electrum
 
+using namespace system;
 using namespace interface;
 using namespace std::placeholders;
 
@@ -50,8 +51,8 @@ void protocol_electrum::start() NOEXCEPT
     SUBSCRIBE_RPC(handle_blockchain_block_header, _1, _2, _3, _4);
     SUBSCRIBE_RPC(handle_blockchain_block_headers, _1, _2, _3, _4, _5);
     SUBSCRIBE_RPC(handle_blockchain_headers_subscribe, _1, _2);
-    SUBSCRIBE_RPC(handle_blockchain_estimatefee, _1, _2, _3);
-    SUBSCRIBE_RPC(handle_blockchain_relayfee, _1, _2);
+    SUBSCRIBE_RPC(handle_blockchain_estimate_fee, _1, _2, _3, _4);
+    SUBSCRIBE_RPC(handle_blockchain_relay_fee, _1, _2);
     SUBSCRIBE_RPC(handle_blockchain_scripthash_get_balance, _1, _2, _3);
     SUBSCRIBE_RPC(handle_blockchain_scripthash_get_history, _1, _2, _3);
     SUBSCRIBE_RPC(handle_blockchain_scripthash_get_mempool, _1, _2, _3);
@@ -99,22 +100,60 @@ void protocol_electrum::handle_blockchain_block_headers(const code& ec,
 void protocol_electrum::handle_blockchain_headers_subscribe(const code& ec,
     rpc_interface::blockchain_headers_subscribe) NOEXCEPT
 {
-    if (stopped(ec)) return;
-    send_code(error::not_implemented);
+    if (stopped(ec))
+        return;
+
+    const auto& query = archive();
+    const auto link = query.to_header(query.get_top_confirmed_hash());
+    const auto height = query.get_height(link);
+    const auto header = query.get_header(link);
+    if (height.is_terminal() || !header)
+    {
+        send_code(error::not_found);
+        return;
+    }
+
+    // See protocol_native::to_hex().
+    std::string hex(two * chain::header::serialized_size(), '\0');
+    stream::out::fast sink{ hex };
+    write::base16::fast writer{ sink };
+    header->to_data(writer);
+    BC_ASSERT(writer);
+
+    // TODO: subscribe to block confirmation (idempotent).
+    // TODO: upon notification send just the notifying header.
+    // TODO: it is client responsiblity to deal with reorgs and race gaps.
+    send_result(value_t
+        {
+            object_t
+            {
+                { "height", height.value },
+                { "hex", hex }
+            }
+        }, 256, BIND(complete, _1));
 }
 
-void protocol_electrum::handle_blockchain_estimatefee(const code& ec,
-    rpc_interface::blockchain_estimatefee, double ) NOEXCEPT
+void protocol_electrum::handle_blockchain_estimate_fee(const code& ec,
+    rpc_interface::blockchain_estimate_fee, double number,
+    const std::string& ) NOEXCEPT
 {
-    if (stopped(ec)) return;
-    send_code(error::not_implemented);
+    if (stopped(ec))
+        return;
+
+    // TODO: estimate fees from blocks based on expected block inclusion.
+    // TODO: this can be computed from recent blocks and cached by the server.
+    // TODO: update the cache before boradcasting header notifications.
+    send_result(number, 70, BIND(complete, _1));
 }
 
-void protocol_electrum::handle_blockchain_relayfee(const code& ec,
-    rpc_interface::blockchain_relayfee) NOEXCEPT
+void protocol_electrum::handle_blockchain_relay_fee(const code& ec,
+    rpc_interface::blockchain_relay_fee) NOEXCEPT
 {
-    if (stopped(ec)) return;
-    send_code(error::not_implemented);
+    if (stopped(ec))
+        return;
+
+    // TODO: implement from [node] config, removed in protocol 1.6.
+    send_result(0.00000001, 70, BIND(complete, _1));
 }
 
 void protocol_electrum::handle_blockchain_scripthash_get_balance(const code& ec,
@@ -210,8 +249,10 @@ void protocol_electrum::handle_server_add_peer(const code& ec,
 void protocol_electrum::handle_server_banner(const code& ec,
     rpc_interface::server_banner) NOEXCEPT
 {
-    if (stopped(ec)) return;
-    send_code(error::not_implemented);
+    if (stopped(ec))
+        return;
+
+    send_result(network_settings().user_agent, 70, BIND(complete, _1));
 }
 
 void protocol_electrum::handle_server_donation_address(const code& ec,
@@ -248,8 +289,19 @@ void protocol_electrum::handle_server_ping(const code& ec,
 void protocol_electrum::handle_mempool_get_fee_histogram(const code& ec,
     rpc_interface::mempool_get_fee_histogram) NOEXCEPT
 {
-    if (stopped(ec)) return;
-    send_code(error::not_implemented);
+    if (stopped(ec))
+        return;
+
+    // TODO: requires tx pool metadata graph.
+    send_result(value_t
+        {
+            array_t
+            {
+                array_t{ 1, 1024 },
+                array_t{ 2, 2048 },
+                array_t{ 4, 4096 }
+            }
+        }, 256, BIND(complete, _1));
 }
 
 BC_POP_WARNING()