[RFC-9250]: Add QUIC server support (#6182)

Add DNS-over-QUIC server 

Signed-off-by: jaehnri <joao.henri.cr@gmail.com>
Signed-off-by: João Henri <joao.henri.cr@gmail.com>

plugin/metrics/README.md

@@ -21,6 +21,7 @@ the following metrics are exported:
 * `coredns_dns_response_size_bytes{server, zone, view, proto}` - response size in bytes.
 * `coredns_dns_responses_total{server, zone, view, rcode, plugin}` - response per zone, rcode and plugin.
 * `coredns_dns_https_responses_total{server, status}` - responses per server and http status code.
+* `coredns_dns_quic_responses_total{server, status}` - responses per server and QUIC application code.
 * `coredns_plugin_enabled{server, zone, view, name}` - indicates whether a plugin is enabled on per server, zone and view basis.
 
 Almost each counter has a label `zone` which is the zonename used for the request/response.

plugin/metrics/vars/vars.go

@@ -72,6 +72,13 @@ var (
 		Name:      "https_responses_total",
 		Help:      "Counter of DoH responses per server and http status code.",
 	}, []string{"server", "status"})
+
+	QUICResponsesCount = promauto.NewCounterVec(prometheus.CounterOpts{
+		Namespace: plugin.Namespace,
+		Subsystem: subsystem,
+		Name:      "quic_responses_total",
+		Help:      "Counter of DoQ responses per server and QUIC application code.",
+	}, []string{"server", "status"})
 )
 
 const (

plugin/pkg/parse/host.go

@@ -61,6 +61,8 @@ func HostPortOrFile(s ...string) ([]string, error) {
 				ss = net.JoinHostPort(host, transport.Port)
 			case transport.TLS:
 				ss = transport.TLS + "://" + net.JoinHostPort(host, transport.TLSPort)
+			case transport.QUIC:
+				ss = transport.QUIC + "://" + net.JoinHostPort(host, transport.QUICPort)
 			case transport.GRPC:
 				ss = transport.GRPC + "://" + net.JoinHostPort(host, transport.GRPCPort)
 			case transport.HTTPS:

plugin/pkg/parse/transport.go

@@ -19,6 +19,10 @@ func Transport(s string) (trans string, addr string) {
 		s = s[len(transport.DNS+"://"):]
 		return transport.DNS, s
 
+	case strings.HasPrefix(s, transport.QUIC+"://"):
+		s = s[len(transport.QUIC+"://"):]
+		return transport.QUIC, s
+
 	case strings.HasPrefix(s, transport.GRPC+"://"):
 		s = s[len(transport.GRPC+"://"):]
 		return transport.GRPC, s

plugin/pkg/transport/transport.go

@@ -4,6 +4,7 @@ package transport
 const (
 	DNS   = "dns"
 	TLS   = "tls"
+	QUIC  = "quic"
 	GRPC  = "grpc"
 	HTTPS = "https"
 	UNIX  = "unix"
@@ -15,6 +16,8 @@ const (
 	Port = "53"
 	// TLSPort is the default port for DNS-over-TLS.
 	TLSPort = "853"
+	// QUICPort is the default port for DNS-over-QUIC.
+	QUICPort = "853"
 	// GRPCPort is the default port for DNS-over-gRPC.
 	GRPCPort = "443"
 	// HTTPSPort is the default port for DNS-over-HTTPS.