Add electrum server setting maximum_headers.

Author: evoskuil

include/bitcoin/server/settings.hpp

@@ -84,6 +84,17 @@ class BCS_API settings
         virtual bool enabled() const NOEXCEPT;
     };
 
+    struct electrum_server
+      : public network::settings::tls_server
+    {
+        using base = network::settings::tls_server;
+        using base::base;
+
+        // Maximum number of headers the server will return in single request.
+        // Recommended to be multiple of difficulty retarget period, e.g. 2016.
+        uint32_t maximum_headers{ 10 * 2016 };
+    };
+
     /// html (http/s) document server settings (has directory/default).
     /// This is for web servers that expose a local file system directory.
     struct html_server
@@ -128,7 +139,7 @@ class BCS_API settings
     network::settings::http_server bitcoind{ "bitcoind" };
 
     /// electrum compat interface (tcp/s, json-rpc-v2)
-    network::settings::tls_server electrum{ "electrum" };
+    electrum_server electrum{ "electrum" };
 
     /// stratum v1 compat interface (tcp/s, json-rpc-v1, auth handshake)
     network::settings::tls_server stratum_v1{ "stratum_v1" };

src/parser.cpp

@@ -1129,6 +1129,11 @@ options_metadata parser::load_settings() THROWS
         value<uint32_t>(&configured.server.electrum.maximum_request),
         "The maximum allowed request size, defaults to '4000000'."
     )
+    (
+        "electrum.maximum_headers",
+        value<uint32_t>(&configured.server.electrum.maximum_headers),
+        "The maximum allowed header request cound, defaults to '20160'."
+    )
 
     /* [stratum_v1] */
     (

test/settings.cpp

@@ -230,6 +230,9 @@ BOOST_AUTO_TEST_CASE(server__electrum_server__defaults__expected)
     BOOST_REQUIRE(server.cert_path.empty());
     BOOST_REQUIRE(server.key_path.empty());
     BOOST_REQUIRE(server.key_pass.empty());
+
+    // electrum_server
+    BOOST_REQUIRE_EQUAL(server.maximum_headers, 10u * 2016u);
 }
 
 BOOST_AUTO_TEST_CASE(server__stratum_v1_server__defaults__expected)