detect socket type without resolve. added test.

Signed-off-by: Martin Kjær Jørgensen <me@lagy.org>

cmd/dex/serve.go

@@ -10,10 +10,12 @@ import (
 	"net"
 	"net/http"
 	"net/http/pprof"
+	"net/url"
 	"os"
 	"os/signal"
 	"path/filepath"
 	"runtime"
+	"strconv"
 	"strings"
 	"sync/atomic"
 	"syscall"
@@ -90,13 +92,28 @@ func commandServe() *cobra.Command {
 
 // try detect the intended socket type from address string
 func getSocketType(address string) string {
-	_, resErr := net.ResolveTCPAddr("tcp", address)
-	if resErr == nil {
-		return "tcp"
-	} else {
-		// assume UNIX socket
-		return "unix"
+	if h, p, serr := net.SplitHostPort(address); serr == nil {
+		// if port string is a number, assume tcp
+		if _, cerr := strconv.Atoi(p); cerr == nil {
+			return "tcp"
+		}
+		// otherwise results in unix socket path
+		return h
+	}
+
+	if u, perr := url.Parse(address); perr == nil {
+		if len(u.Scheme) > 0 {
+			// if scheme is recognized use that
+			return u.Scheme
+		} else {
+			// when parser gets a file path Scheme is
+			// empty. so default to unix socket.
+			return "unix"
+		}
 	}
+
+	// assume unix file path
+	return "unix"
 }
 
 func runServe(options serveOptions) error {

cmd/dex/serve_test.go

@@ -27,3 +27,26 @@ func TestNewLogger(t *testing.T) {
 		require.Equal(t, (*slog.Logger)(nil), logger)
 	})
 }
+
+func TestGetSocketType(t *testing.T) {
+	urls := [][]string{
+		{"tcp://127.0.0.1:8080", "tcp"},
+		{"unix:///tmp/my.sock", "unix"},
+		{"127.0.0.1:9000", "tcp"},
+		{"/var/run/app.sock", "unix"},
+		{"./socket.sock", "unix"},
+		{"relative.sock", "unix"},
+		{"example.com:80", "tcp"},
+		{"unix://./run/rel.sock", "unix"},
+		{"[::1]:443", "tcp"},
+		{"[::FFFF:129.144.52.38]:80", "tcp"},
+		{"a/b/c", "unix"},
+		{"/d/e/f", "unix"},
+		{"localhost:80", "tcp"},
+	}
+	for _, url := range urls {
+		t.Run(url[0], func(t *testing.T) {
+			require.Equal(t, url[1], getSocketType(url[0]))
+		})
+	}
+}