interop: simplify API of http09.Server (#4651)

Removes the ListenAndServe method in favor of a ServeListener method.

interop/http09/server.go

@@ -5,17 +5,15 @@ import (
 	"errors"
 	"io"
 	"log"
-	"net"
 	"net/http"
 	"net/url"
 	"runtime"
 	"strings"
-	"sync"
 
 	"github.com/quic-go/quic-go"
 )
 
-const h09alpn = "hq-interop"
+const NextProto = "hq-interop"
 
 type responseWriter struct {
 	io.Writer
@@ -36,51 +34,14 @@ func (w *responseWriter) WriteHeader(int) {}
 // Server is a HTTP/0.9 server listening for QUIC connections.
 type Server struct {
 	*http.Server
-
-	ForceRetry bool
-	QuicConfig *quic.Config
-
-	mutex    sync.Mutex
-	listener *quic.EarlyListener
-}
-
-// Close closes the server.
-func (s *Server) Close() error {
-	s.mutex.Lock()
-	defer s.mutex.Unlock()
-
-	return s.listener.Close()
 }
 
 // ListenAndServe listens and serves HTTP/0.9 over QUIC.
-func (s *Server) ListenAndServe() error {
+func (s *Server) ServeListener(ln *quic.EarlyListener) error {
 	if s.Server == nil {
 		return errors.New("use of http3.Server without http.Server")
 	}
 
-	udpAddr, err := net.ResolveUDPAddr("udp", s.Addr)
-	if err != nil {
-		return err
-	}
-	conn, err := net.ListenUDP("udp", udpAddr)
-	if err != nil {
-		return err
-	}
-
-	tlsConf := s.TLSConfig.Clone()
-	tlsConf.NextProtos = []string{h09alpn}
-	tr := quic.Transport{Conn: conn}
-	if s.ForceRetry {
-		tr.VerifySourceAddress = func(net.Addr) bool { return true }
-	}
-	ln, err := tr.ListenEarly(tlsConf, s.QuicConfig)
-	if err != nil {
-		return err
-	}
-	s.mutex.Lock()
-	s.listener = ln
-	s.mutex.Unlock()
-
 	for {
 		conn, err := ln.Accept(context.Background())
 		if err != nil {