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, 4 insertions, 3 deletions

diff --git a/admin.go b/admin.go
index 36cc2f8..a23a1ac 100644
--- a/admin.go
+++ b/admin.go
@@ -382,7 +382,7 @@ func replaceLocalAdminServer(cfg *Config) error {
 
 	handler := cfg.Admin.newAdminHandler(addr, false)
 
-	ln, err := Listen(addr.Network, addr.JoinHostPort(0))
+	ln, err := addr.Listen(context.TODO(), 0, net.ListenConfig{})
 	if err != nil {
 		return err
 	}
@@ -403,7 +403,7 @@ func replaceLocalAdminServer(cfg *Config) error {
 		serverMu.Lock()
 		server := localAdminServer
 		serverMu.Unlock()
-		if err := server.Serve(ln); !errors.Is(err, http.ErrServerClosed) {
+		if err := server.Serve(ln.(net.Listener)); !errors.Is(err, http.ErrServerClosed) {
 			adminLogger.Error("admin server shutdown for unknown reason", zap.Error(err))
 		}
 	}()
@@ -549,10 +549,11 @@ func replaceRemoteAdminServer(ctx Context, cfg *Config) error {
 	serverMu.Unlock()
 
 	// start listener
-	ln, err := Listen(addr.Network, addr.JoinHostPort(0))
+	lnAny, err := addr.Listen(ctx, 0, net.ListenConfig{})
 	if err != nil {
 		return err
 	}
+	ln := lnAny.(net.Listener)
 	ln = tls.NewListener(ln, tlsConfig)
 
 	go func() {