> [!IMPORTANT]
> **Breaking Changes**
> - DecodePacket and EncodePacket delegates replaced with IClientEncryption interface
> - NetState.Connection (Socket) replaced with internal RingSocket management
> - NetState.RecvPipe and NetState.SendPipe removed (buffers managed internally)
## Summary
Upgrades the networking stack from PollGroup-based I/O to io_uring, significantly improving I/O performance on Linux.
This also adds native client encryption support for encrypted UO clients.
## Major Changes
io_uring Networking Architecture
- Replaced PollGroup with IORingGroup for async socket I/O operations
- Removed Pipe.cs (mirrored ring buffer) and TcpServer.cs in favor of RingSocketManager
- Added NetState.Network.cs - centralized network infrastructure handling accept, recv, send, and disconnect
completions
- Added SocketHelper.cs - platform-specific socket utilities for raw socket handle operations (getpeername,
getsockname)
- Buffer management now handled by RingSocketManager with configurable slab allocation
### Client Encryption Support
- Added full encryption stack in Network/Encryption/:
- EncryptionConfig.cs - configurable encryption modes (None, Unencrypted, Encrypted, Both)
- EncryptionManager.cs - encryption detection and initialization for login/game packets
- LoginEncryption.cs - handles login packet encryption with version-derived keys
- GameEncryption.cs - handles game server encryption using Twofish
- TwofishEngine.cs - optimized Twofish block cipher implementation
- LoginKeys.cs - encryption key table for client versions
- IClientEncryption.cs - interface for client encryption implementations
### NetState Improvements
- Replaced Socket Connection with RingSocket _socket for managed socket lifecycle
- Changed from GCHandle polling to event-based completion processing
- Disconnect handling now properly waits for pending sends to flush
- Simplified connecting socket management using lazy queue removal
### Configuration
- New settings: network.encryptionMode and network.encryptionDebug
- Encryption mode flags: Unencrypted, Encrypted, or Both
### Dependencies
- Replaced PollGroup NuGet package with IORingGroup
- Linux requires liburing-dev / liburing-devel package
### Test plan
- Verify server starts and accepts connections on Linux with io_uring
- Verify server starts and accepts connections on Windows (fallback to IOCP)
- Test unencrypted client connections (ClassicUO with encryption disabled)
- Test encrypted client connections if available
- Verify graceful disconnect flushes pending data
- Confirm CI builds pass on all target platforms
> [!Important]
> **Developer Note**
> This code change will **completely move gumps out of the core**
### Summary
- Adds `GetGumps()` convenience which exposes methods to Find/Close/Send multiple gumps. This helper is a performance improvement by eliminating the Dictionary<Player, List> lookup for gumps.
# New Gump API
We are pleased to release a new API that is faster, allocates nearly zero memory, and still feels very similar to the original API. The API is broken into 3 types of gumps, dynamic, static with placeholders, and static without placeholders.
### Dynamic Gumps
These gumps will inherit `DynamicGump` and are meant for gumps that have a dynamic layout. This includes specifying dynamic arguments to HtmlLocalized entries.
## Static Gumps
Static gumps are those where the function to the build the layout is called only once and cached forever. They can optionally have placeholders. These placeholders allow the developer to specify the string values later, dynamically in a `BuildStrings` method on the gump. If a gump does not have any placeholders, the string entries will also be cached forever.
## Benchmarks
To make sure we were going in the right direction and not wasting time, we took copious benchmarks. Here are the final benchmarks for a really simple gump.
Note:
* The majority of creating a gump is compressing the layout and the strings. Compressing each section takes ~6,000ns (12us total).
```cs
| Method | Mean | Error | StdDev | Median | Ratio | RatioSD | Gen0 | Allocated | Alloc Ratio |
|------------------------------- |-------------:|-------------:|-------------:|-------------:|------:|--------:|-------:|----------:|------------:|
| OldGump | 13,308.29 ns | 1,059.695 ns | 1,883.608 ns | 14,330.72 ns | 1.000 | 0.00 | 0.1526 | 2400 B | 1.00 |
| DynamicLayoutGump | 13,357.86 ns | 129.144 ns | 226.185 ns | 13,323.60 ns | 1.029 | 0.17 | - | 48 B | 0.02 |
| StaticLayoutDynamicStringsGump | 6,653.10 ns | 81.815 ns | 143.292 ns | 6,617.45 ns | 0.514 | 0.09 | - | 40 B | 0.02 |
| StaticLayoutGump | 86.33 ns | 0.760 ns | 1.350 ns | 86.07 ns | 0.007 | 0.00 | 0.0020 | 32 B | 0.01 |
```
# Non-Breaking Changes
* All gump components in the core have been moved to `Gumps/Legacy`.
* All legacy gumps will still inherit `Gump`, which now inherits `BaseGump`
# Special Thanks
Thank you to @stefanomerotta for considerable contributions/benchmarking/testing to make this effort a reality! We collectively went through over 10 iterations, but it is finally ready.
### Summary
* Removes old gump packet support
* Removes support for v4 clients
* Removes `Unpack` flag and assumes it is always true.
* Removes StringToBuffer since this is built into .NET now.
> [!Note]
> View the file changes with white space off: https://github.com/modernuo/ModernUO/pull/1739/files?diff=split&w=1
## Breaking Changes
Incoming packet registration signature has changed to:
```cs
delegate* void OnReceiveCallback(NetState state, SpanReader reader, int packetLength);
IncomingPackets.Register(int packetID, int length, bool ingame, OnReceiveCallback onReceive);
```
For example, an incoming packet handler signature would now look like this:
```cs
public static void SomeIncomingPacket(NetState state, SpanReader reader, int packetLength)
{
// Parse the data
}
```
## Summary
Updates the network Pipe class to use a mirrored memory technique. This technique involves mapping the same physical memory to two contiguous virtual memory spaces so the byte buffer appears duplicated. This allows writing to a double-sized array to wrap around without the need for the `CircularBuffer` classes.
In practice this allows us to use `Span<byte>` as if the buffer was a regular array.
### Bug Fixes
- [X] Fixes bad fixed length string parsing
Changes gump compilation to use string interpolation. .NET 6 uses code generation and compile time tricks to speed up string interpolation between 15 and 30% and reduce allocations dramatically.
