Report neo-node version from getversion (neo-node#983)

plugins/RpcServer/RpcServer.Node.cs

@@ -123,7 +123,7 @@ private static JObject GetRelayResult(VerifyResult reason, UInt256 hash)
     ///   "result": {
     ///     "tcpport": 10333, // The TCP port,
     ///     "nonce": 1, // The nonce,
-    ///     "useragent": "The user agent",
+    ///     "useragent": "/Neo:3.10.2/", // Node assembly version in the existing useragent field,
     ///     "rpc": {
     ///       "maxiteratorresultitems": 100, // The maximum number of items in the iterator result,
     ///       "sessionenabled": false // Whether session is enabled,
@@ -152,7 +152,8 @@ protected internal virtual JToken GetVersion()
         JObject json = new();
         json["tcpport"] = localNode.ListenerTcpPort;
         json["nonce"] = LocalNode.Nonce;
-        json["useragent"] = LocalNode.UserAgent;
+        var nodeVersion = typeof(RpcServer).Assembly.GetName().Version?.ToString(3) ?? "0.0.0";
+        json["useragent"] = UserAgentWithVersion(LocalNode.UserAgent, nodeVersion);
         // rpc settings
         JObject rpc = new();
         rpc["maxiteratorresultitems"] = settings.MaxIteratorResultItems;
@@ -183,6 +184,19 @@ protected internal virtual JToken GetVersion()
         return json;
     }
 
+    /// <summary>
+    /// Keeps the P2P useragent product name and replaces the version with <paramref name="version"/>.
+    /// <c>/Neo:3.10.1/</c> plus <c>3.10.2</c> becomes <c>/Neo:3.10.2/</c>.
+    /// </summary>
+    internal static string UserAgentWithVersion(string userAgent, string version)
+    {
+        var colon = userAgent.IndexOf(':');
+        var slash = userAgent.LastIndexOf('/');
+        if (colon >= 0 && slash > colon)
+            return string.Concat(userAgent.AsSpan(0, colon + 1), version, userAgent.AsSpan(slash));
+        return $"/Neo:{version}/";
+    }
+
     /// <summary>
     /// Removes a specified prefix from a string if it exists.
     /// </summary>

tests/Neo.Plugins.RpcServer.Tests/UT_RpcServer.Node.cs

@@ -117,6 +117,17 @@ public void TestGetVersion()
         Assert.IsTrue(json.ContainsProperty("tcpport"));
         Assert.IsTrue(json.ContainsProperty("nonce"));
         Assert.IsTrue(json.ContainsProperty("useragent"));
+        Assert.IsFalse(json.ContainsProperty("version"));
+        var nodeVersion = _rpcServer.GetType().Assembly.GetName().Version?.ToString(3) ?? "0.0.0";
+        Assert.AreEqual(RpcServer.UserAgentWithVersion(LocalNode.UserAgent, nodeVersion), json["useragent"]!.AsString());
+        Assert.Contains($":{nodeVersion}/", json["useragent"]!.AsString());
+
+        Assert.IsTrue(json.ContainsProperty("rpc"));
+        var rpc = (JObject)json["rpc"]!;
+        Assert.IsTrue(rpc.ContainsProperty("maxiteratorresultitems"));
+        Assert.IsTrue(rpc.ContainsProperty("sessionenabled"));
+        Assert.AreEqual(_rpcServerSettings.MaxIteratorResultItems, rpc["maxiteratorresultitems"]!.AsNumber());
+        Assert.AreEqual(_rpcServerSettings.SessionEnabled, rpc["sessionenabled"]!.AsBoolean());
 
         Assert.IsTrue(json.ContainsProperty("protocol"));
         var protocol = (JObject)json["protocol"];
@@ -132,6 +143,15 @@ public void TestGetVersion()
         Assert.IsTrue(protocol.ContainsProperty("seedlist"));
     }
 
+    [TestMethod]
+    public void TestUserAgentWithVersion_ReplacesVersionKeepsProduct()
+    {
+        Assert.AreEqual("/Neo:3.10.2/", RpcServer.UserAgentWithVersion("/Neo:3.10.1/", "3.10.2"));
+        Assert.AreEqual("/MyNode:3.10.2/", RpcServer.UserAgentWithVersion("/MyNode:1.0.0/", "3.10.2"));
+        Assert.AreEqual("/Neo:3.10.2/", RpcServer.UserAgentWithVersion("not-a-ua", "3.10.2"));
+        Assert.AreEqual("/Neo:3.10.2/", RpcServer.UserAgentWithVersion(string.Empty, "3.10.2"));
+    }
+
     [TestMethod]
     public void TestGetVersion_HardforksStructure()
     {