add a basic QUIC spec (#499)

* add a basic QUIC spec

* fix spec status

Co-authored-by: Max Inden <[email protected]>

* specify ALPN and link to libp2p TLS

* add link to QUIC spec to README

Co-authored-by: Max Inden <[email protected]>

README.md

@@ -90,6 +90,7 @@ The protocols described below all use [protocol buffers](https://developers.goog
   peer discovery
 - [secio][spec_secio] - SECIO, a transport security protocol for libp2p
 - [tls][spec_tls] - The libp2p TLS Handshake (TLS 1.3+)
+- [quic][spec_quic] - The libp2p QUIC Handshake
 - [webrtc][spec_webrtc] - The libp2p WebRTC transport
 - [WebTransport][spec_webtransport] - Using WebTransport in libp2p
 
@@ -122,6 +123,7 @@ you feel an issue isn't the appropriate place for your topic, please join our
 [spec_rendezvous]: ./rendezvous/README.md
 [spec_secio]: ./secio/README.md
 [spec_tls]: ./tls/tls.md
+[spec_quic]: ./quic/README.md
 [spec_peerids]: ./peer-ids/peer-ids.md
 [spec_connections]: ./connections/README.md
 [spec_plaintext]: ./plaintext/README.md

quic/README.md

@@ -0,0 +1,52 @@
+# QUIC in libp2p
+
+| Lifecycle Stage | Maturity      | Status | Latest Revision |
+|-----------------|---------------|--------|-----------------|
+| 3A              | Recommendation | Active | r1, 2022-12-30  |
+
+Authors: [@marten-seemann]
+
+Interest Group: [@elenaf9], [@MarcoPolo]
+
+[@marten-seemann]: https://github.com/marten-seemann
+[@elenaf9]: https://github.com/elenaf9
+[@MarcoPolo]: https://github.com/MarcoPolo
+
+See the [lifecycle document][lifecycle-spec] for context about the maturity level
+and spec status.
+
+[lifecycle-spec]: https://github.com/libp2p/specs/blob/master/00-framework-01-spec-lifecycle.md
+
+## QUIC vs. TCP
+
+QUIC [RFC9000] is, alongside TCP, one of the transports that allows non-browser libp2p nodes to establish connections to each other.
+Due to its inherently faster handshake latency (a single network-roundtrip), and generally better performance characteristics, it is RECOMMENDED that libp2p implementations offer QUIC as one of their transports.
+However, UDP is blocked in a small fraction of networks, therefore it is RECOMMENDED that libp2p nodes offer a TCP-based connection option as a fallback.
+
+### Multiaddress
+
+A QUIC multiaddress encodes the IP address and UDP port. For example, these are valid QUIC multiaddresses:
+* `/ip4/127.0.0.1/udp/1234/quic-v1`: A QUIC listener running on localhost on port 1234.
+* `/ip6/2001:db8:3333:4444:5555:6666:7777:8888/udp/443/quic-v1`: A QUIC listener running on 2001:db8:3333:4444:5555:6666:7777:8888 on port 443.
+* `/ip4/12.34.56.78/udp/4321/quic`: A QUIC listener, supporting QUIC draft-29 (see below) 
+
+### QUIC Versions
+
+When IPFS first rolled out QUIC support, RFC 9000 was not finished yet. Back then, QUIC was rolled out based on [IETF QUIC working group draft-29].
+Nodes supporting draft-29 use the `/quic` multiaddress component (instead of `/quic-v1`) to signal support for the draft version.
+Nodes supporting RFC 9000 use the `/quic-v1` multiaddress component.
+
+New implementations SHOULD implement support for RFC 9000. Support for draft-29 is currently being phased out of production networks, and will be deprecated at some point in the future.
+
+### ALPN
+
+"libp2p" is used as the application protocol for ALPN.
+Note that QUIC enforces the use of ALPN, so the handshake will fail if both peers can't agree on the application protocol.
+
+### Peer Authentication
+
+Peers authenticate each other using the TLS handshake logic described in the [libp2p TLS spec].
+
+[RFC9000]: https://datatracker.ietf.org/doc/html/rfc9000
+[IETF QUIC working group draft-29]: https://datatracker.ietf.org/doc/html/draft-ietf-quic-transport-29
+[libp2p TLS spec]: ../tls