QUIC matcher: initial commit (#262)

README.md

@@ -37,6 +37,7 @@ Current matchers:
 - **layer4.matchers.openvpn** - matches connections that look like [OpenVPN](https://openvpn.net/community-resources/openvpn-protocol/) connections.
 - **layer4.matchers.postgres** - matches connections that look like Postgres connections.
 - **layer4.matchers.proxy_protocol** - matches connections that start with [HAPROXY proxy protocol](https://www.haproxy.org/download/1.8/doc/proxy-protocol.txt).
+- **layer4.matchers.quic** - matches connections that look like [QUIC](https://quic.xargs.org/).
 - **layer4.matchers.rdp** - matches connections that look like [RDP](https://winprotocoldoc.blob.core.windows.net/productionwindowsarchives/MS-RDPBCGR/%5BMS-RDPBCGR%5D.pdf).
 - **layer4.matchers.regexp** - matches connections that have the first packet bytes matching a regular expression.
 - **layer4.matchers.remote_ip** - matches connections based on remote IP (or CIDR range).

imports.go

@@ -25,6 +25,7 @@ import (
 	_ "github.com/mholt/caddy-l4/modules/l4postgres"
 	_ "github.com/mholt/caddy-l4/modules/l4proxy"
 	_ "github.com/mholt/caddy-l4/modules/l4proxyprotocol"
+	_ "github.com/mholt/caddy-l4/modules/l4quic"
 	_ "github.com/mholt/caddy-l4/modules/l4rdp"
 	_ "github.com/mholt/caddy-l4/modules/l4regexp"
 	_ "github.com/mholt/caddy-l4/modules/l4socks"

integration/caddyfile_adapt/gd_matcher_quic.caddytest

@@ -0,0 +1,83 @@
+{
+	layer4 {
+		udp/:8843 {
+			@q1 quic sni one.com two.com
+			route @q1 {
+				proxy udp/{l4.quic.tls.server_name}:443
+			}
+			@q2 quic {
+				alpn custom
+				sni example.com
+			}
+			route @q2 {
+				proxy udp/localhost:6543
+			}
+		}
+	}
+}
+----------
+{
+	"apps": {
+		"layer4": {
+			"servers": {
+				"srv0": {
+					"listen": [
+						"udp/:8843"
+					],
+					"routes": [
+						{
+							"match": [
+								{
+									"quic": {
+										"sni": [
+											"one.com",
+											"two.com"
+										]
+									}
+								}
+							],
+							"handle": [
+								{
+									"handler": "proxy",
+									"upstreams": [
+										{
+											"dial": [
+												"udp/{l4.quic.tls.server_name}:443"
+											]
+										}
+									]
+								}
+							]
+						},
+						{
+							"match": [
+								{
+									"quic": {
+										"alpn": [
+											"custom"
+										],
+										"sni": [
+											"example.com"
+										]
+									}
+								}
+							],
+							"handle": [
+								{
+									"handler": "proxy",
+									"upstreams": [
+										{
+											"dial": [
+												"udp/localhost:6543"
+											]
+										}
+									]
+								}
+							]
+						}
+					]
+				}
+			}
+		}
+	}
+}