Limits

Libraries/Esiur/Data/Codec.cs

@@ -649,6 +649,7 @@ public static class Codec
     public static byte[] Compose(object valueOrSource, Warehouse warehouse, EpConnection connection)
     {
         var tdu = ComposeInternal(valueOrSource, warehouse, connection);
+        ParserGuard.EnsureRemotePacketSize(connection, (ulong)tdu.Composed.LongLength);
         return tdu.Composed;
     }
 

Libraries/Esiur/Data/DataSerializer.cs

@@ -363,6 +363,10 @@ public static class DataSerializer
     public static Tdu StringComposer(object value, Warehouse warehouse, EpConnection connection)
     {
         var b = Encoding.UTF8.GetBytes((string)value);
+        ParserGuard.EnsureRemoteAllocation(
+            connection,
+            ParserGuard.MultiplySaturated((ulong)b.LongLength, 2),
+            "string");
 
         return new Tdu(TduIdentifier.String, b, (uint)b.Length, null, null);
     }
@@ -370,6 +374,10 @@ public static class DataSerializer
     public static Tdu ResourceLinkComposer(object value, Warehouse warehouse, EpConnection connection)
     {
         var b = Encoding.UTF8.GetBytes((ResourceLink)value);
+        ParserGuard.EnsureRemoteAllocation(
+            connection,
+            ParserGuard.MultiplySaturated((ulong)b.LongLength, 2),
+            "resource link");
 
         return new Tdu(TduIdentifier.ResourceLink, b, (uint)b.Length, null, null);
     }
@@ -446,12 +454,14 @@ public static class DataSerializer
     public static Tdu RawDataComposerFromArray(object value, Warehouse warehouse, EpConnection connection)
     {
         var b = (byte[])value;
+        ParserGuard.EnsureRemoteAllocation(connection, (ulong)b.LongLength, "raw data");
         return new Tdu(TduIdentifier.RawData, b, (uint)b.Length, null, null);
     }
 
     public static Tdu RawDataComposerFromList(dynamic value, Warehouse warehouse, EpConnection connection)
     {
         var b = value as List<byte>;
+        ParserGuard.EnsureRemoteAllocation(connection, (ulong)b.Count, "raw data");
         return new Tdu(TduIdentifier.RawData, b.ToArray(), (uint)b.Count, null, null);
     }
 
@@ -516,6 +526,9 @@ public static class DataSerializer
         if (value == null)
             return null;
 
+        if (value is ICollection collection)
+            ParserGuard.EnsureRemoteCollectionCount(connection, collection.Count, GetTypedArrayElementSize(tru));
+
         if (tru.Identifier == TruIdentifier.Int32)
         {
             composed = GroupInt32Codec.Encode((IList<int>)value);
@@ -748,12 +761,18 @@ public static class DataSerializer
 
         // Pre-size the buffer from the element count (when known) to avoid repeated
         // List<byte> reallocations as items are appended. 4 bytes/element is a rough hint.
-        var rt = new List<byte>(value is ICollection collection ? collection.Count * 4 : 16);
+        var knownCount = value is ICollection collection ? collection.Count : -1;
+        if (knownCount >= 0)
+            ParserGuard.EnsureRemoteCollectionCount(connection, knownCount, IntPtr.Size);
+        var rt = new List<byte>(knownCount >= 0 ? knownCount * 4 : 16);
 
         Tdu? previous = null;
+        var count = 0;
 
         foreach (var i in value)
         {
+            if (knownCount < 0)
+                ParserGuard.EnsureRemoteCollectionCount(connection, ++count, IntPtr.Size);
             var tdu = Codec.ComposeInternal(i, warehouse, connection);
             if (previous != null && tdu.MatchType(previous.Value))
             {
@@ -862,13 +881,24 @@ public static class DataSerializer
 
         var rt = new List<byte>();
         var map = (IMap)value;
+        var serialized = map.Serialize();
+        ParserGuard.EnsureRemoteCollectionCount(connection, serialized.Length, IntPtr.Size);
 
-        foreach (var el in map.Serialize())
+        foreach (var el in serialized)
             rt.AddRange(Codec.Compose(el, warehouse, connection));
 
         return new Tdu(TduIdentifier.Map, rt.ToArray(), (uint)rt.Count, null, null);
     }
 
+    static int GetTypedArrayElementSize(Tru tru)
+        => tru.Identifier switch
+        {
+            TruIdentifier.Int16 or TruIdentifier.UInt16 => 2,
+            TruIdentifier.Int32 or TruIdentifier.UInt32 => 4,
+            TruIdentifier.Int64 or TruIdentifier.UInt64 => 8,
+            _ => IntPtr.Size
+        };
+
     /// <summary>
     /// Composes an indexed CLR structure using the compatible Map&lt;byte, object&gt; wire shape.
     /// </summary>

Libraries/Esiur/Data/ParserGuard.cs

@@ -15,6 +15,16 @@ public sealed class ParserLimitException : Exception
     }
 }
 
+/// <summary>
+/// Raised before transmission when a composed value exceeds a budget advertised by the peer.
+/// </summary>
+public sealed class RemoteParserLimitException : Exception
+{
+    public RemoteParserLimitException(string message) : base(message)
+    {
+    }
+}
+
 internal static class ParserGuard
 {
     internal static Warehouse? GetWarehouse(EpConnection? connection)
@@ -70,4 +80,64 @@ internal static class ParserGuard
 
     internal static ulong MultiplySaturated(ulong value, ulong multiplier)
         => value > ulong.MaxValue / multiplier ? ulong.MaxValue : value * multiplier;
+
+    internal static void EnsureRemotePacketSize(EpConnection? connection, ulong size)
+    {
+        var limit = connection?.Session?.RemoteMaximumPacketSize ?? 0;
+        if (limit > 0 && size > limit)
+            throw new RemoteParserLimitException(
+                $"Composed packet payload of {size} bytes exceeds the peer's advertised {limit}-byte limit.");
+    }
+
+    internal static void EnsureRemoteAllocation(
+        EpConnection? connection,
+        ulong size,
+        string kind)
+    {
+        var limit = connection?.Session?.RemoteMaximumAllocationSize ?? 0;
+        if (limit > 0 && size > limit)
+            throw new RemoteParserLimitException(
+                $"Composed {kind} would allocate {size} bytes at the peer, exceeding its advertised {limit}-byte limit.");
+    }
+
+    internal static void EnsureRemoteCollectionCount(
+        EpConnection? connection,
+        int count,
+        int estimatedBytesPerItem = 0)
+    {
+        var limit = connection?.Session?.RemoteMaximumCollectionItems ?? 0;
+        if (limit > 0 && count > limit)
+            throw new RemoteParserLimitException(
+                $"Composed collection has {count} items, exceeding the peer's advertised {limit}-item limit.");
+
+        if (estimatedBytesPerItem > 0)
+            EnsureRemoteAllocation(
+                connection,
+                MultiplySaturated((ulong)count, (ulong)estimatedBytesPerItem),
+                "collection");
+    }
+
+    internal static void EnsureRemoteTypeMetadataDepth(EpConnection? connection, Tru? tru)
+    {
+        var limit = connection?.Session?.RemoteMaximumTypeMetadataDepth ?? 0;
+        if (limit <= 0 || tru == null)
+            return;
+
+        var depth = GetTypeMetadataDepth(tru);
+        if (depth > limit)
+            throw new RemoteParserLimitException(
+                $"Composed TRU type metadata depth of {depth} exceeds the peer's advertised limit of {limit}.");
+    }
+
+    static int GetTypeMetadataDepth(Tru tru)
+    {
+        if (tru is not TruComposite composite || composite.SubTypes == null || composite.SubTypes.Length == 0)
+            return 1;
+
+        var maximumChildDepth = 0;
+        foreach (var child in composite.SubTypes)
+            maximumChildDepth = Math.Max(maximumChildDepth, GetTypeMetadataDepth(child));
+
+        return 1 + maximumChildDepth;
+    }
 }

Libraries/Esiur/Data/Tdu.cs

@@ -176,6 +176,7 @@ public struct Tdu
             if (metadata == null)
                 throw new Exception("Metadata must be provided for types.");
 
+            ParserGuard.EnsureRemoteTypeMetadataDepth(connection, metadata);
             var metadataData = metadata.Compose(connection);
 
 

Libraries/Esiur/Net/Packets/EpAuthPacketHeader.cs

@@ -23,6 +23,11 @@ namespace Esiur.Net.Packets
         AuthenticationProtocol,
         AuthenticationData,
         ErrorMessage,
-        CipherNonce
+        CipherNonce,
+        MaximumPacketSize,
+        MaximumAllocationSize,
+        MaximumCollectionItems,
+        MaximumTypeMetadataDepth,
+        MaximumEncryptedRecordSize
     }
 }

Libraries/Esiur/Protocol/EpConnection.cs

@@ -369,17 +369,25 @@ public partial class EpConnection : NetworkConnection, IStore
         var provider = _session.EncryptionProvider
             ?? throw new InvalidOperationException("Session encryption is active without a provider.");
         var maximumRecordSize = ParsingWarehouse.Configuration.Encryption.MaximumRecordSize;
+        var remoteMaximumRecordSize = _session?.RemoteMaximumEncryptedRecordSize ?? 0;
 
         if (maximumRecordSize > 0
             && (ulong)plaintext.LongLength + provider.MaximumRecordOverhead > maximumRecordSize)
             throw new ParserLimitException(
                 $"Encrypted record would exceed the {maximumRecordSize}-byte limit.");
+        if (remoteMaximumRecordSize > 0
+            && (ulong)plaintext.LongLength + provider.MaximumRecordOverhead > remoteMaximumRecordSize)
+            throw new RemoteParserLimitException(
+                $"Encrypted record would exceed the peer's advertised {remoteMaximumRecordSize}-byte limit.");
 
         var protectedPayload = cipher.Encrypt(plaintext);
 
         if (maximumRecordSize > 0 && protectedPayload.Length > maximumRecordSize)
             throw new InvalidOperationException(
                 $"Encryption provider `{provider.DefaultName}` exceeded its declared record overhead.");
+        if (remoteMaximumRecordSize > 0 && protectedPayload.Length > remoteMaximumRecordSize)
+            throw new RemoteParserLimitException(
+                $"Encrypted record of {protectedPayload.Length} bytes exceeds the peer's advertised {remoteMaximumRecordSize}-byte limit.");
         if (protectedPayload.Length > int.MaxValue - EncryptedRecordHeaderSize)
             throw new ParserLimitException("Encrypted record exceeds the runtime allocation limit.");
 
@@ -454,6 +462,7 @@ public partial class EpConnection : NetworkConnection, IStore
             }
         }
 
+        PopulateLocalLimitHeaders();
         var headers = _session.LocalHeaders.Copy();
 
         // Anonymous sessions still exchange typed records. They therefore
@@ -491,6 +500,16 @@ public partial class EpConnection : NetworkConnection, IStore
             | ((byte)_session.EncryptionMode & 0x3)), headers);
     }
 
+    void PopulateLocalLimitHeaders()
+    {
+        var configuration = ParsingWarehouse.Configuration;
+        _session.LocalHeaders.MaximumPacketSize = configuration.Parser.MaximumPacketSize;
+        _session.LocalHeaders.MaximumAllocationSize = configuration.Parser.MaximumAllocationSize;
+        _session.LocalHeaders.MaximumCollectionItems = configuration.Parser.MaximumCollectionItems;
+        _session.LocalHeaders.MaximumTypeMetadataDepth = configuration.Parser.MaximumTypeMetadataDepth;
+        _session.LocalHeaders.MaximumEncryptedRecordSize = configuration.Encryption.MaximumRecordSize;
+    }
+
     void PrepareEncryptionOffer()
     {
         if (_session.AuthenticationMode == AuthenticationMode.None)
@@ -1653,6 +1672,7 @@ public partial class EpConnection : NetworkConnection, IStore
                         ? $"anonymous:{RemoteEndPoint?.Address}"
                         : remoteHeaders.Domain;
                     _session.AuthenticationMode = _authPacket.AuthMode;
+                    PopulateLocalLimitHeaders();
                     var localHeaders = _session.LocalHeaders.Copy();
 
                     if (!NegotiateEncryptionAsResponder(localHeaders))
@@ -1787,6 +1807,16 @@ public partial class EpConnection : NetworkConnection, IStore
                     if (_session.AuthenticationMode == AuthenticationMode.None
                         && _authPacket.Method == EpAuthPacketMethod.SessionEstablished)
                     {
+                        var remoteHeaders = new SessionHeaders();
+                        if (_authPacket.Tdu != null)
+                        {
+                            remoteHeaders = Codec.ParseIndexedType<SessionHeaders>(
+                                _authPacket.Tdu.Value,
+                                ParsingWarehouse);
+                            remoteHeaders.AuthenticationData = null;
+                        }
+                        _session.RemoteHeaders = remoteHeaders;
+
                         _session.Authenticated = true;
                         _session.LocalIdentity = null;
                         _session.RemoteIdentity = null;

Libraries/Esiur/Protocol/EpConnectionProtocol.cs

@@ -329,7 +329,18 @@ partial class EpConnection
         //callbackCounter++; // avoid thread racing
         _requests.Add(c, reply);
 
+        try
+        {
             SendRequestPacket(action, c, args);
+        }
+        catch (RemoteParserLimitException ex)
+        {
+            _requests.Take(c);
+            reply.TriggerError(new AsyncException(
+                ErrorType.Management,
+                (ushort)ExceptionCode.ParserLimitExceeded,
+                ex.Message));
+        }
         return reply;
     }
 
@@ -372,7 +383,18 @@ partial class EpConnection
             () => SendRequest(EpPacketRequest.ResumeExecution, callbackId));
 
         _requests.Add(callbackId, reply);
+        try
+        {
             SendRequestPacket(action, callbackId, args);
+        }
+        catch (RemoteParserLimitException ex)
+        {
+            _requests.Take(callbackId);
+            reply.TriggerError(new AsyncException(
+                ErrorType.Management,
+                (ushort)ExceptionCode.ParserLimitExceeded,
+                ex.Message));
+        }
         return reply;
     }
 
@@ -387,7 +409,18 @@ partial class EpConnection
             () => SendRequest(EpPacketRequest.ResumeExecution, callbackId));
 
         _requests.Add(callbackId, reply);
+        try
+        {
             SendRequestPacket(action, callbackId, args);
+        }
+        catch (RemoteParserLimitException ex)
+        {
+            _requests.Take(callbackId);
+            reply.TriggerError(new AsyncException(
+                ErrorType.Management,
+                (ushort)ExceptionCode.ParserLimitExceeded,
+                ex.Message));
+        }
         return reply;
     }
 
@@ -502,6 +535,8 @@ partial class EpConnection
         if (Instance == null)
             return;
 
+        try
+        {
             if (args.Length == 0)
             {
                 var bl = new BinaryList();
@@ -509,7 +544,7 @@ partial class EpConnection
                   .AddUInt32(callbackId);
                 Send(bl.ToArray());
             }
-        if (args.Length == 1)
+            else if (args.Length == 1)
             {
                 var bl = new BinaryList();
                 bl.AddUInt8((byte)(0xA0 | (byte)action))
@@ -526,6 +561,18 @@ partial class EpConnection
                 Send(bl.ToArray());
             }
         }
+        catch (RemoteParserLimitException ex) when (
+            action != EpPacketReply.PermissionError
+            && action != EpPacketReply.ExecutionError
+            && action != EpPacketReply.Warning)
+        {
+            SendError(
+                ErrorType.Exception,
+                callbackId,
+                (ushort)ExceptionCode.ParserLimitExceeded,
+                ex.Message);
+        }
+    }
 
 
     internal AsyncReply SendSubscribeRequest(uint instanceId, byte index)
@@ -677,7 +724,19 @@ partial class EpConnection
             return;
         }
 
-        var pr = Codec.Parse(tdu.Value, this, null);
+        object pr;
+        try
+        {
+            pr = Codec.Parse(tdu.Value, this, null);
+        }
+        catch (ParserLimitException ex)
+        {
+            req.TriggerError(new AsyncException(
+                ErrorType.Management,
+                (ushort)ExceptionCode.ParserLimitExceeded,
+                ex.Message));
+            return;
+        }
 
         if (pr is AsyncReply asyncReply)
         {
@@ -724,7 +783,20 @@ partial class EpConnection
             return;
         }
 
-        var value = Codec.Parse(tdu, this, null);
+        object value;
+        try
+        {
+            value = Codec.Parse(tdu, this, null);
+        }
+        catch (ParserLimitException ex)
+        {
+            _requests.Take(callbackId);
+            req.TriggerError(new AsyncException(
+                ErrorType.Management,
+                (ushort)ExceptionCode.ParserLimitExceeded,
+                ex.Message));
+            return;
+        }
 
         if (value is AsyncReply reply)
         {
@@ -819,7 +891,20 @@ partial class EpConnection
         if (req == null)
             return;
 
-        var value = Codec.Parse(tdu, this, null);
+        object value;
+        try
+        {
+            value = Codec.Parse(tdu, this, null);
+        }
+        catch (ParserLimitException ex)
+        {
+            _requests.Take(callbackId);
+            req.TriggerError(new AsyncException(
+                ErrorType.Management,
+                (ushort)ExceptionCode.ParserLimitExceeded,
+                ex.Message));
+            return;
+        }
 
         if (value is AsyncReply asyncReply)
         {
@@ -3993,6 +4078,14 @@ partial class EpConnection
 
     private void Instance_PropertyModified(PropertyModificationInfo info)
     {
+        // Attachment permission does not imply property-read permission. A
+        // method-only resource can be attached so its exported functions are
+        // callable while all of its properties remain private. Re-evaluate the
+        // property operation before broadcasting each modification, matching
+        // the permission checks already applied to event notifications.
+        if (!IsOperationAllowed(info.Resource, info.PropertyDef, ActionType.GetProperty))
+            return;
+
         SendNotification(EpPacketNotification.PropertyModified,
                          info.Resource.Instance.Id,
                          info.Cursor.Generation.ToByteArray(),

Libraries/Esiur/Security/Authority/Session.cs

@@ -100,6 +100,21 @@ public sealed class SessionHeaders : IndexedStructure
     [Index((int)EpAuthPacketHeader.CipherNonce)]
     public byte[]? CipherNonce { get; set; }
 
+    [Index((int)EpAuthPacketHeader.MaximumPacketSize)]
+    public uint? MaximumPacketSize { get; set; }
+
+    [Index((int)EpAuthPacketHeader.MaximumAllocationSize)]
+    public uint? MaximumAllocationSize { get; set; }
+
+    [Index((int)EpAuthPacketHeader.MaximumCollectionItems)]
+    public int? MaximumCollectionItems { get; set; }
+
+    [Index((int)EpAuthPacketHeader.MaximumTypeMetadataDepth)]
+    public int? MaximumTypeMetadataDepth { get; set; }
+
+    [Index((int)EpAuthPacketHeader.MaximumEncryptedRecordSize)]
+    public uint? MaximumEncryptedRecordSize { get; set; }
+
     internal SessionHeaders Copy() => (SessionHeaders)MemberwiseClone();
 }
 
@@ -121,6 +136,12 @@ public class Session
     public SessionHeaders LocalHeaders { get; set; } = new SessionHeaders();
     public SessionHeaders RemoteHeaders { get; set; } = new SessionHeaders();
 
+    public uint RemoteMaximumPacketSize => RemoteHeaders?.MaximumPacketSize ?? 0;
+    public uint RemoteMaximumAllocationSize => RemoteHeaders?.MaximumAllocationSize ?? 0;
+    public int RemoteMaximumCollectionItems => RemoteHeaders?.MaximumCollectionItems ?? 0;
+    public int RemoteMaximumTypeMetadataDepth => RemoteHeaders?.MaximumTypeMetadataDepth ?? 0;
+    public uint RemoteMaximumEncryptedRecordSize => RemoteHeaders?.MaximumEncryptedRecordSize ?? 0;
+
     //public AuthenticationMethod AuthenticationMethod { get; set; }
     //public AuthenticationMethod RemoteMethod { get; set; }
 

Tests/Unit/Integration/AttachmentSecurityTests.cs

@@ -1,5 +1,10 @@
 using Esiur.Core;
+using Esiur.Data;
+using Esiur.Data.Types;
 using Esiur.Protocol;
+using Esiur.Resource;
+using Esiur.Security.Authority;
+using Esiur.Security.Permissions;
 
 namespace Esiur.Tests.Unit.Integration;
 
@@ -36,10 +41,68 @@ public class AttachmentSecurityTests
         Assert.Equal(1, cluster.Connection.ResourceAttachRequestCount);
     }
 
+    [Fact]
+    public async Task PropertyNotifications_RespectPerPropertyReadPermission()
+    {
+        PropertyBroadcastResource? source = null;
+        await using var cluster = await IntegrationCluster.StartAsync(async warehouse =>
+        {
+            var permissions = new PropertyBroadcastPermissions();
+            warehouse.RegisterManager(permissions);
+            source = await warehouse.Put("sys/property-broadcast", new PropertyBroadcastResource());
+            source.Instance!.Managers.Add(permissions);
+        }).WaitAsync(TimeSpan.FromSeconds(10));
+
+        var remote = (EpResource)await cluster.Connection.Get("sys/property-broadcast");
+        var received = new List<string>();
+        remote.Instance.PropertyModified += info => received.Add(info.PropertyDef.Name);
+
+        source!.Secret = 7;
+        source.Visible = 9;
+
+        var deadline = DateTime.UtcNow + TimeSpan.FromSeconds(3);
+        while (!received.Contains(nameof(PropertyBroadcastResource.Visible)) &&
+               DateTime.UtcNow < deadline)
+            await Task.Delay(20);
+
+        Assert.Contains(nameof(PropertyBroadcastResource.Visible), received);
+        Assert.DoesNotContain(nameof(PropertyBroadcastResource.Secret), received);
+    }
+
     static Task<IntegrationCluster> StartCluster()
         => IntegrationCluster.StartAsync(async warehouse =>
         {
             await warehouse.Put("sys/first", new RateLimitedResource());
             await warehouse.Put("sys/second", new RateLimitedResource());
         });
+
+    sealed class PropertyBroadcastPermissions : IPermissionsManager
+    {
+        public Map<string, object> Settings { get; } = new();
+
+        public Ruling Applicable(
+            IResource resource,
+            Session session,
+            ActionType action,
+            MemberDef member,
+            object inquirer = null!)
+        {
+            if (action == ActionType.Attach)
+                return Ruling.Allowed;
+            if (action == ActionType.GetProperty)
+                return member?.Name == nameof(PropertyBroadcastResource.Secret)
+                    ? Ruling.Denied
+                    : Ruling.Allowed;
+            return Ruling.DontCare;
+        }
+
+        public bool Initialize(Map<string, object> settings, IResource resource) => true;
+    }
+}
+
+[Resource]
+public partial class PropertyBroadcastResource
+{
+    [Export] int secret;
+    [Export] int visible;
 }

Tests/Unit/Integration/SessionHeadersIntegrationTests.cs

@@ -12,6 +12,46 @@ using System.Net;
 [Collection("Integration")]
 public class SessionHeadersIntegrationTests
 {
+    [Fact]
+    public async Task Handshake_ExchangesParserAndEncryptedRecordBudgetsInBothDirections()
+    {
+        await using var cluster = await IntegrationCluster
+            .StartAsync(
+                warehouse =>
+                {
+                    warehouse.Configuration.Parser.MaximumPacketSize = 7_100_001;
+                    warehouse.Configuration.Parser.MaximumAllocationSize = 3_100_002;
+                    warehouse.Configuration.Parser.MaximumCollectionItems = 51_003;
+                    warehouse.Configuration.Parser.MaximumTypeMetadataDepth = 54;
+                    warehouse.Configuration.Encryption.MaximumRecordSize = 7_101_004;
+                    return Task.CompletedTask;
+                },
+                populateClient: warehouse =>
+                {
+                    warehouse.Configuration.Parser.MaximumPacketSize = 6_200_001;
+                    warehouse.Configuration.Parser.MaximumAllocationSize = 2_200_002;
+                    warehouse.Configuration.Parser.MaximumCollectionItems = 42_003;
+                    warehouse.Configuration.Parser.MaximumTypeMetadataDepth = 45;
+                    warehouse.Configuration.Encryption.MaximumRecordSize = 6_201_004;
+                    return Task.CompletedTask;
+                })
+            .WaitAsync(TimeSpan.FromSeconds(10));
+
+        var serverConnection = Assert.Single(cluster.Server.Connections);
+
+        Assert.Equal(7_100_001u, cluster.Connection.Session.RemoteMaximumPacketSize);
+        Assert.Equal(3_100_002u, cluster.Connection.Session.RemoteMaximumAllocationSize);
+        Assert.Equal(51_003, cluster.Connection.Session.RemoteMaximumCollectionItems);
+        Assert.Equal(54, cluster.Connection.Session.RemoteMaximumTypeMetadataDepth);
+        Assert.Equal(7_101_004u, cluster.Connection.Session.RemoteMaximumEncryptedRecordSize);
+
+        Assert.Equal(6_200_001u, serverConnection.Session.RemoteMaximumPacketSize);
+        Assert.Equal(2_200_002u, serverConnection.Session.RemoteMaximumAllocationSize);
+        Assert.Equal(42_003, serverConnection.Session.RemoteMaximumCollectionItems);
+        Assert.Equal(45, serverConnection.Session.RemoteMaximumTypeMetadataDepth);
+        Assert.Equal(6_201_004u, serverConnection.Session.RemoteMaximumEncryptedRecordSize);
+    }
+
     [Fact]
     public async Task AcceptedConnection_RaisesReadyAndDisconnectedLifecycleEvents()
     {

Tests/Unit/ParserSecurityTests.cs

@@ -7,6 +7,27 @@ namespace Esiur.Tests.Unit;
 
 public class ParserSecurityTests
 {
+    [Fact]
+    public void Composer_RejectsValuesAbovePeerAdvertisedBudgetsBeforeSend()
+    {
+        var warehouse = new Warehouse();
+        var connection = new EpConnection();
+        connection.Session.RemoteHeaders.MaximumPacketSize = 64;
+        connection.Session.RemoteHeaders.MaximumAllocationSize = 6;
+        connection.Session.RemoteHeaders.MaximumCollectionItems = 2;
+
+        Assert.Throws<RemoteParserLimitException>(() =>
+            Codec.Compose("four", warehouse, connection));
+        Assert.Throws<RemoteParserLimitException>(() =>
+            Codec.Compose(new object[] { 1, 2, 3 }, warehouse, connection));
+
+        connection.Session.RemoteHeaders.MaximumAllocationSize = 0;
+        connection.Session.RemoteHeaders.MaximumCollectionItems = 0;
+        connection.Session.RemoteHeaders.MaximumPacketSize = 3;
+        Assert.Throws<RemoteParserLimitException>(() =>
+            Codec.Compose(new byte[] { 1, 2, 3, 4 }, warehouse, connection));
+    }
+
     [Fact]
     public void PacketParser_RejectsOversizedDeclarationBeforePayloadArrives()
     {