logging: Fix default access logger (#6251)

* logging: Fix default access logger

* Simplify logic, remove retry without port, reject config with port, docs

* Nil check

modules/caddyhttp/app.go

@@ -329,9 +329,10 @@ func (app *App) Provision(ctx caddy.Context) error {
 
 // Validate ensures the app's configuration is valid.
 func (app *App) Validate() error {
-	// each server must use distinct listener addresses
 	lnAddrs := make(map[string]string)
+
 	for srvName, srv := range app.Servers {
+		// each server must use distinct listener addresses
 		for _, addr := range srv.Listen {
 			listenAddr, err := caddy.ParseNetworkAddress(addr)
 			if err != nil {
@@ -347,6 +348,15 @@ func (app *App) Validate() error {
 				lnAddrs[addr] = srvName
 			}
 		}
+
+		// logger names must not have ports
+		if srv.Logs != nil {
+			for host := range srv.Logs.LoggerNames {
+				if _, _, err := net.SplitHostPort(host); err == nil {
+					return fmt.Errorf("server %s: logger name must not have a port: %s", srvName, host)
+				}
+			}
+		}
 	}
 	return nil
 }