core: Refactor and improve listener logic (#5089)

* core: Refactor, improve listener logic

Deprecate:
- caddy.Listen
- caddy.ListenTimeout
- caddy.ListenPacket

Prefer caddy.NetworkAddress.Listen() instead.

Change:
- caddy.ListenQUIC (hopefully to remove later)
- caddy.ListenerFunc signature (add context and ListenConfig)

- Don't emit Alt-Svc header advertising h3 over HTTP/3

- Use quic.ListenEarly instead of quic.ListenEarlyAddr; this gives us
more flexibility (e.g. possibility of HTTP/3 over UDS) but also
introduces a new issue:
https://github.com/lucas-clemente/quic-go/issues/3560#issuecomment-1258959608

- Unlink unix socket before and after use

* Appease the linter

* Keep ListenAll

1 files changed, 32 insertions, 8 deletions

diff --git a/modules/caddyhttp/server.go b/modules/caddyhttp/server.go
index 5daa5b2..4d47d26 100644
--- a/modules/caddyhttp/server.go
+++ b/modules/caddyhttp/server.go
@@ -170,9 +170,10 @@ type Server struct {
 	errorLogger  *zap.Logger
 	ctx          caddy.Context
 
-	server    *http.Server
-	h3server  *http3.Server
-	addresses []caddy.NetworkAddress
+	server      *http.Server
+	h3server    *http3.Server
+	h3listeners []net.PacketConn // TODO: we have to hold these because quic-go won't close listeners it didn't create
+	addresses   []caddy.NetworkAddress
 
 	shutdownAt   time.Time
 	shutdownAtMu *sync.RWMutex
@@ -193,9 +194,11 @@ func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		atomic.AddInt64(&s.activeRequests, 1)
 		defer atomic.AddInt64(&s.activeRequests, -1)
 
-		err := s.h3server.SetQuicHeaders(w.Header())
-		if err != nil {
-			s.logger.Error("setting HTTP/3 Alt-Svc header", zap.Error(err))
+		if r.ProtoMajor < 3 {
+			err := s.h3server.SetQuicHeaders(w.Header())
+			if err != nil {
+				s.logger.Error("setting HTTP/3 Alt-Svc header", zap.Error(err))
+			}
 		}
 	}
 
@@ -493,8 +496,27 @@ func (s *Server) findLastRouteWithHostMatcher() int {
 // serveHTTP3 creates a QUIC listener, configures an HTTP/3 server if
 // not already done, and then uses that server to serve HTTP/3 over
 // the listener, with Server s as the handler.
-func (s *Server) serveHTTP3(hostport string, tlsCfg *tls.Config) error {
-	h3ln, err := caddy.ListenQUIC(hostport, tlsCfg, &s.activeRequests)
+func (s *Server) serveHTTP3(addr caddy.NetworkAddress, tlsCfg *tls.Config) error {
+	switch addr.Network {
+	case "unix":
+		addr.Network = "unixgram"
+	case "tcp":
+		addr.Network = "udp"
+	case "tcp4":
+		addr.Network = "udp4"
+	case "tcp6":
+		addr.Network = "udp6"
+	default:
+		return fmt.Errorf("unsure what network to use for HTTP/3 given network type: %s", addr.Network)
+	}
+
+	lnAny, err := addr.Listen(s.ctx, 0, net.ListenConfig{})
+	if err != nil {
+		return err
+	}
+	ln := lnAny.(net.PacketConn)
+
+	h3ln, err := caddy.ListenQUIC(ln, tlsCfg, &s.activeRequests)
 	if err != nil {
 		return fmt.Errorf("starting HTTP/3 QUIC listener: %v", err)
 	}
@@ -512,6 +534,8 @@ func (s *Server) serveHTTP3(hostport string, tlsCfg *tls.Config) error {
 		}
 	}
 
+	s.h3listeners = append(s.h3listeners, lnAny.(net.PacketConn))
+
 	//nolint:errcheck
 	go s.h3server.ServeListener(h3ln)