mvfst (Pronounced move fast) is a client and server implementation of IETF QUIC protocol in C++ by Facebook. QUIC is a UDP based reliable, multiplexed transport protocol that will become an internet standard. The goal of
mvfst is to build a performant implementation of the QUIC transport protocol that applications could adapt for use cases on both the internet and the data-center.
mvfst has been tested at scale on android, iOS apps, as well as servers and has several features to support large scale deployments.
- Multi-threaded UDP socket server with a thread local architecture to be able to scale to multi-core servers
- Customizable Connection-Id routing. The default Connection-Id routing implementation integrates seamlessly with katran
- APIs to enable zero-downtime restarts of servers, so that applications do not have to drop connections when restarting.
- APIs to expose transport and server statistics for debuggability
- Zero-Rtt connection establishment and customizable zero rtt path validation
- Support for UDP Generic segmentation offloading (GSO) for faster UDP writes.
- Native happy eyeballs support between ipv4 and ipv6 so that applications do not need to implement it themselves
- Pluggable congestion control and support for turning off congestion control to plug in application specific control algorithms
- QUIC trace APIs to retrieve deep transport level stats.
quic/api: Defines API that applications can use to interact with the QUIC transport layer.
quic/client: Client transport implementation
quic/codec: Read and write codec implementation for the protocol
quic/common: Implementation of common utility functions
quic/congestion_control: Implementation of different congestion control algorithms such as Cubic and Copa
quic/flowcontrol: Implementations of flow control functions
quic/handshake: Implementations cryptographic handshake layer
quic/happyeyeballs: Implementation of mechanism to race IPV4 and IPV6 connection and pick a winner
quic/logging: Implementation of logging framework
quic/loss: Implementations of different loss recovery algorithms
quic/samples: Example client and server
quic/server: Server transport implementation
quic/state: Defines and implements both connection and stream level state artifacts and state machines
sudo apt-get install \ g++ \ cmake \ libboost-all-dev \ libevent-dev \ libdouble-conversion-dev \ libgoogle-glog-dev \ libgflags-dev \ libiberty-dev \ liblz4-dev \ liblzma-dev \ libsnappy-dev \ make \ zlib1g-dev \ binutils-dev \ libjemalloc-dev \ libssl-dev \ pkg-config \ libsodium-dev
Then, build and install folly and fizz
Alternatively, run the helper script
build_helper.sh in this subdirectory.
It will install and link the required dependencies and also build folly and fizz.
This may take several minutes the first time.
After building, the directory
_build/ will contain the dependencies
_build/build will contain all the
built libraries and binaries for
You can also install
mvfst as well as its dependencies
to a custom directory using the build script, by supplying an
./build_helper.sh -i /usr/local
./build_helper.sh --help for more options
You might need to run the script as root to install to certain directories.
By default the build script
build_helper.sh enables the building of test target (i.e. runs with
-DBUILD_TEST=ON option). Since some of tests in
mvfst require some test artifacts of Fizz, it is necessary to supply the path of the Fizz src directory (via option
DFIZZ_PROJECT) to correctly build all test targets in
Run a sample client and server
Building the test targets of
mvfst (or via
build_helper.sh) should automatically build the sample client and server binaries as well. The server will automatically bind to
::1 by default if no host is used, but you can then spin a simple echo server by running:
./quic/samples/echo -mode=server -host=<host> -port=<port>
and to run a client:
./quic/samples/echo -mode=client -host=<host> -port=<port>
For more options, see
We'd love to have your help in making
mvfst better. If you're interested, please
read our guide to guide to contributing
Please also join our slack to ask questions or start discussions.
mvfst is MIT licensed, as found in the LICENSE file.
The API should be considered in alpha. We can't predict all the use cases that people will have, so we're waiting some time before declaring a more stable API. We are open to have several different APIs for different constraints.
Reporting and Fixing Security Issues
Please do not open GitHub issues or pull requests - this makes the problem
immediately visible to everyone, including malicious actors. Security issues in
mvfst can be safely reported via Facebook's Whitehat Bug Bounty program:
Facebook's security team will triage your report and determine whether or not is it eligible for a bounty under our program.