Ruffles is a fully managed UDP library designed for high performance and low latency.
Why another reliable UDP library?
There are many RUDP libraries such as ENET, Lidgren, LiteNetLib. While many of them are great, Ruffles aims to fill in one niche that is largely not filled, that being lightweight fully managed libraries.
To compare to the examples above, ENET is amazing and is pretty much what Ruffles want to be, but it's unmanaged. Lidgren, LiteNetLib and many other managed libraries can feel too bloated and contain many features that are unnecessary and they are often much slower.
Ruffles is still WIP, more features might come.
The Ruffle protocol requires a challenge to be completed before a connection can be established. Currently, the challenge is a hashcash like challenge that is supplied by the server, brute force solved by the client and submitted. (Uses Fowler-Noll-Vo hash function instead of SHA1 currently).
DOS Amplification Prevention
DOS amplification is prevented by requiring unproportional connection message sizes. In addition, because of the connection challenge it's not computationally feasible to attack on Layer 4.
Slot Filling Prevention
Ruffles has a fixed amount of connection slots that can be used for pending connections, this limits the usability of slot filling attacks on Layer 4. Pending connections have a fixed timeout to solve the computationally expensive HashCash challenge before being knocked out, the slot will be available once again after that. As this only limits slot filling attacks, Ruffles also has a security mechanism where a HashCash has to be solved in the first message. This challenge is generated by the client and the server will verify that the date used is recent and that the IV has not already been used, forcing clients to recompute the HashCash challenge every time they want to initialize a handshake.
With these security mitigations, the only way to bring the server down is to exhaust all CPU resources.
Ruffles handles all connection management for you. It's a fully connection oriented protocol with heartbeat keepalive packets sent to ensure the connection is alive.
Ruffles is fully garbage free, this is accomplished with a custom memory allocator in GC space. This ensures no memory is leaked to the garbage collector unless for resizing purposes. This makes Ruffles blazing fast. It also avoids memory copies as much as possible.
Reliability and Sequencing
There are currently a few ways of sending messages in Ruffles. The types are:
All messages are guaranteed to be delivered, the order is not guaranteed, duplicates are dropped. Uses a fixed sliding window.
All messages are guaranteed to be delivered with the order also being guaranteed, duplicates are dropped. Uses a fixed sliding window.
Delivery is not guaranteed, nor is the order. Duplicates are dropped.
Delivery is not guaranteed but the order is. Older packets and duplicate packets are dropped.
Delivery is not guaranteed nor is the order. Duplicates are not dropped.
Ruffles can run in many different threading environments, it can be run passively single threaded, actively single threaded, or in a threaded environment where everything is done via message queues while remaining garbage free.
Ruffles is 100% dependency free, it's thus very portable and should run on most platforms.
IPv6 Dual Mode
Ruffles supports IPv6 dual socket mode. It does this by using two sockets bound to the same port, thus accomplishing full dual stack functionality that is invisible to the user.
Small Packet Merging
Small packets will be delayed for sending, this allows them to be merged into one larger packet. This can be disabled and enabled on a per packet basis. The delay and max merge size can also be configured.
This is stuff I want to and plan to add
- Path MTU
- Explicit Nack
- Layer 4 DOS Prevention with an on-connect HashCash challenge
- Reliable StateUpdate / LastPacket channel
- MLAPI.Relay Support
- MLAPI.NAT (Holepuncher) support
- Bloatless Moduled Library (Make all the garbage features like relay support separate modules to keep the core library bloat free and small)
Here are the features that are considered but not decided. This is to prevent bloat.
- Meshing / Peer relaying