🐛 bug: Handle Unix sockets in adaptor middleware (#3760)

* Fix Fiber v3 adapter for Unix socket testing

* test(adaptor): use temp dir for Unix socket and skip on non-Unix

* formatted test file and handle error check

* resolves issues in adapter test

* *net.TCPaddr to net.addr

* fixes in adaptor test

* fixes in adaptor test

* fixes in adaptor test

* checked error return in adataptor test

* resolved variable shadowing in adaptor test

* resolved variable shadowing in adaptor test

* resolved variable shadowing in adaptor test

* added resolveRemoteAddr function for resolving addr properly

* changes in resolveRemoteAddr function

* resolved lint error

* added test for bad remote address

* resolve lint issue in adaptor test

* resolve lint issue in adaptor test

Author: Dishank-Sen

middleware/adaptor/adaptor.go

@@ -1,6 +1,8 @@
 package adaptor
 
 import (
+	"errors"
+	"fmt"
 	"io"
 	"net"
 	"net/http"
@@ -138,6 +140,32 @@ func FiberApp(app *fiber.App) http.HandlerFunc {
 	return handlerFunc(app)
 }
 
+func isUnixNetwork(network string) bool {
+	return network == "unix" || network == "unixgram" || network == "unixpacket"
+}
+
+func resolveRemoteAddr(remoteAddr string, localAddr any) (net.Addr, error) {
+	if addr, ok := localAddr.(net.Addr); ok && isUnixNetwork(addr.Network()) {
+		return addr, nil
+	}
+
+	resolved, err := net.ResolveTCPAddr("tcp", remoteAddr)
+	if err == nil {
+		return resolved, nil
+	}
+
+	var addrErr *net.AddrError
+	if errors.As(err, &addrErr) && addrErr.Err == "missing port in address" {
+		remoteAddr = net.JoinHostPort(remoteAddr, "80")
+		resolved, err2 := net.ResolveTCPAddr("tcp", remoteAddr)
+		if err2 != nil {
+			return nil, fmt.Errorf("failed to resolve TCP address after adding port: %w", err2)
+		}
+		return resolved, nil
+	}
+	return nil, fmt.Errorf("failed to resolve TCP address: %w", err)
+}
+
 func handlerFunc(app *fiber.App, h ...fiber.Handler) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		req := fasthttp.AcquireRequest()
@@ -164,14 +192,10 @@ func handlerFunc(app *fiber.App, h ...fiber.Handler) http.HandlerFunc {
 			}
 		}
 
-		if _, _, err := net.SplitHostPort(r.RemoteAddr); err != nil && err.(*net.AddrError).Err == "missing port in address" { //nolint:errorlint,forcetypeassert,errcheck // overlinting
-			r.RemoteAddr = net.JoinHostPort(r.RemoteAddr, "80")
-		}
-
-		remoteAddr, err := net.ResolveTCPAddr("tcp", r.RemoteAddr)
+		remoteAddr, err := resolveRemoteAddr(r.RemoteAddr, r.Context().Value(http.LocalAddrContextKey))
 		if err != nil {
-			http.Error(w, utils.StatusMessage(fiber.StatusInternalServerError), fiber.StatusInternalServerError)
-			return
+			// fallback: fasthttp handles nil remoteAddr
+			remoteAddr = nil
 		}
 
 		// New fasthttp Ctx from pool

middleware/adaptor/adaptor_test.go

@@ -10,8 +10,11 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"net/url"
+	"os"
+	"path/filepath"
 	"strings"
 	"testing"
+	"time"
 
 	"github.com/gofiber/fiber/v3"
 	"github.com/stretchr/testify/assert"
@@ -663,3 +666,116 @@ func Benchmark_HTTPHandler(b *testing.B) {
 
 	require.NoError(b, err)
 }
+
+func TestUnixSocketAdaptor(t *testing.T) {
+	dir := t.TempDir()
+	socketPath := filepath.Join(dir, "test.sock")
+	defer func() {
+		if err := os.Remove(socketPath); err != nil {
+			t.Logf("cleanup failed: %v", err)
+		}
+	}()
+
+	app := fiber.New()
+	app.Get("/hello", func(c fiber.Ctx) error {
+		return c.SendString("ok")
+	})
+	handler := FiberApp(app)
+
+	listener, err := net.Listen("unix", socketPath)
+	if err != nil {
+		// Skip on platforms where the "unix" network is unsupported
+		if strings.Contains(err.Error(), "unknown network") ||
+			strings.Contains(err.Error(), "address family not supported") {
+			t.Skipf("Unix domain sockets not supported on this platform: %v", err)
+		}
+		t.Fatal(err)
+	}
+	defer func() {
+		if closeErr := listener.Close(); closeErr != nil {
+			t.Logf("listener close failed: %v", closeErr)
+		}
+	}()
+
+	// start server with timeouts
+	srv := &http.Server{
+		Handler:      handler,
+		ReadTimeout:  5 * time.Second,
+		WriteTimeout: 10 * time.Second,
+	}
+	done := make(chan struct{})
+	go func() {
+		if serveErr := srv.Serve(listener); serveErr != nil && serveErr != http.ErrServerClosed {
+			t.Errorf("http server failed: %v", serveErr)
+		}
+		close(done)
+	}()
+
+	conn, err := net.Dial("unix", socketPath)
+	require.NoError(t, err)
+	defer func() {
+		if closeErr := conn.Close(); closeErr != nil {
+			t.Logf("conn close failed: %v", closeErr)
+		}
+	}()
+
+	// set deadline for both write + read (2s)
+	require.NoError(t, conn.SetDeadline(time.Now().Add(2*time.Second)))
+
+	// write request
+	_, err = conn.Write([]byte("GET /hello HTTP/1.1\r\nHost: localhost\r\n\r\n"))
+	require.NoError(t, err)
+
+	// read response
+	buf := make([]byte, 1024)
+	n, err := conn.Read(buf)
+	require.NoError(t, err)
+
+	// clear deadline to avoid affecting further calls
+	require.NoError(t, conn.SetDeadline(time.Time{}))
+
+	raw := string(buf[:n])
+	t.Logf("Raw response:\n%s", raw)
+	require.Contains(t, raw, "HTTP/1.1 200 OK")
+	require.Contains(t, raw, "ok")
+
+	// now shutdown the server explicitly before waiting for done
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
+	defer cancel()
+	require.NoError(t, srv.Shutdown(ctx))
+
+	select {
+	case <-done:
+	case <-time.After(5 * time.Second):
+		t.Fatal("server shutdown timed out")
+	}
+}
+
+func TestHandlerFunc_FallbackRemoteAddr(t *testing.T) {
+	app := fiber.New()
+	app.Get("/", func(c fiber.Ctx) error {
+		return c.SendString("ok")
+	})
+
+	handler := handlerFunc(app)
+
+	// Fake request with bad RemoteAddr
+	req, err := http.NewRequestWithContext(context.Background(), http.MethodGet, "/", nil)
+	require.NoError(t, err)
+	req.RemoteAddr = "bad-addr"
+
+	rr := httptest.NewRecorder()
+	handler(rr, req)
+
+	res := rr.Result()
+	defer func() {
+		closeErr := res.Body.Close()
+		require.NoError(t, closeErr)
+	}()
+
+	body, err := io.ReadAll(res.Body)
+	require.NoError(t, err)
+
+	require.Equal(t, http.StatusOK, res.StatusCode)
+	require.Contains(t, string(body), "ok")
+}