feat(batch23): implement route subscription propagation and creation helpers

dotnet/src/ZB.MOM.NatsNet.Server/NatsServer.Routes.Subscriptions.cs

@@ -1,8 +1,74 @@
 // Copyright 2012-2026 The NATS Authors
 // Licensed under the Apache License, Version 2.0 (the "License");
 
+using ZB.MOM.NatsNet.Server.Internal;
+using System.IO;
+
 namespace ZB.MOM.NatsNet.Server;
 
 public sealed partial class NatsServer
 {
+    internal void SendSubsToRoute(ClientConnection route, int idx, string account)
+    {
+        if (route == null)
+            return;
+
+        var allSubs = new List<Subscription>(1024);
+        if (idx < 0 || !string.IsNullOrEmpty(account))
+        {
+            var (acc, _) = LookupAccount(account);
+            acc?.Sublist?.LocalSubs(allSubs, includeLeafHubs: false);
+        }
+        else
+        {
+            foreach (var acc in _accounts.Values)
+            {
+                if (acc.RoutePoolIdx != idx)
+                    continue;
+                acc.Sublist?.LocalSubs(allSubs, includeLeafHubs: false);
+            }
+        }
+
+        route.SendRouteSubProtos(allSubs, trace: false, sub => route.CanImport(System.Text.Encoding.ASCII.GetString(sub.Subject)));
+    }
+
+    internal ClientConnection? CreateRoute(Stream? conn, Uri? routeUrl, RouteType routeType, byte gossipMode, string accName)
+    {
+        var opts = GetOpts();
+        var didSolicit = routeUrl != null;
+        var c = new ClientConnection(ClientKind.Router, this, conn ?? new MemoryStream())
+        {
+            Opts = ClientOptions.Default,
+            Route = new Route
+            {
+                Url = routeUrl,
+                RouteType = routeType,
+                DidSolicit = didSolicit,
+                PoolIdx = -1,
+                GossipMode = gossipMode,
+                AccName = string.IsNullOrEmpty(accName) ? null : System.Text.Encoding.ASCII.GetBytes(accName),
+            },
+            Start = DateTime.UtcNow,
+        };
+
+        lock (c)
+        {
+            c.InitClient();
+            if (didSolicit)
+                c.SetRoutePermissions(opts.Cluster.Permissions);
+            c.SetFirstPingTimer();
+        }
+
+        if (didSolicit)
+        {
+            var sendErr = c.SendRouteConnect(_info.Cluster ?? string.Empty, _routeInfo.TlsRequired);
+            if (sendErr != null)
+            {
+                c.CloseConnection(ClosedState.ProtocolViolation);
+                return null;
+            }
+        }
+
+        return c;
+    }
 }