feat(batch3): verify client proxy protocol feature group

dotnet/src/ZB.MOM.NatsNet.Server/ClientConnection.ProxyProto.cs

@@ -0,0 +1,65 @@
+// Copyright 2012-2026 The NATS Authors
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+using System.Net;
+using ZB.MOM.NatsNet.Server.Protocol;
+
+namespace ZB.MOM.NatsNet.Server;
+
+/// <summary>
+/// Client-side PROXY protocol compatibility surface for Batch 3 mappings.
+/// </summary>
+public sealed partial class ClientConnection
+{
+    private IPEndPoint? _proxyRemoteEndPoint;
+
+    /// <summary>
+    /// Returns the proxied remote endpoint when available, otherwise socket remote endpoint.
+    /// Mirrors Go <c>proxyConn.RemoteAddr()</c>.
+    /// </summary>
+    public EndPoint? RemoteAddr()
+    {
+        lock (_mu) { return _proxyRemoteEndPoint ?? GetRemoteEndPoint(); }
+    }
+
+    internal void SetProxyRemoteAddress(ProxyProtocolAddress? address)
+    {
+        lock (_mu)
+        {
+            _proxyRemoteEndPoint = address is null
+                ? null
+                : new IPEndPoint(address.SrcIp, address.SrcPort);
+        }
+    }
+
+    internal static (int version, byte[] header) DetectProxyProtoVersion(Stream conn) =>
+        ProxyProtocolParser.DetectVersion(conn);
+
+    internal static ProxyProtocolAddress? ReadProxyProtoV1Header(Stream conn) =>
+        ProxyProtocolParser.ReadV1Header(conn);
+
+    internal static ProxyProtocolAddress? ReadProxyProtoHeader(Stream conn) =>
+        ProxyProtocolParser.ReadProxyProtoHeader(conn);
+
+    internal static ProxyProtocolAddress? ReadProxyProtoV2Header(Stream conn) =>
+        ProxyProtocolParser.ReadProxyProtoV2Header(conn);
+
+    internal static ProxyProtocolAddress? ParseProxyProtoV2Header(Stream conn, byte[] header) =>
+        ProxyProtocolParser.ParseV2Header(conn, header.AsSpan());
+
+    internal static ProxyProtocolAddress ParseIPv4Addr(Stream conn, ushort addrLen) =>
+        ProxyProtocolParser.ParseIPv4Addr(conn, addrLen);
+
+    internal static ProxyProtocolAddress ParseIPv6Addr(Stream conn, ushort addrLen) =>
+        ProxyProtocolParser.ParseIPv6Addr(conn, addrLen);
+}