fix(mirror): prevent infinite loop in MirrorMiddleware

Co-authored-by: Junie <junie@jetbrains.com>

pkg/service/handlers/mirror_loop_prevention_test.go

@@ -0,0 +1,53 @@
+package handlers
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"testing"
+
+	"github.com/gesellix/bose-soundtouch/pkg/service/datastore"
+)
+
+func TestMirrorMiddleware_InfiniteLoop(t *testing.T) {
+	tempDir, err := os.MkdirTemp("", "mirror-loop-test")
+	if err != nil {
+		t.Fatalf("Failed to create temp dir: %v", err)
+	}
+	defer os.RemoveAll(tempDir)
+
+	ds := datastore.NewDataStore(tempDir)
+	_ = ds.Initialize()
+
+	server := NewServer(ds, nil, "http://localhost:8000", false, false, false)
+	server.SetMirrorSettings(true, []string{"/loop"}, "upstream")
+
+	// Create a handler that would be the "next" in the chain.
+	// If the loop occurs, this will be called repeatedly.
+	callCount := 0
+	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		callCount++
+		w.WriteHeader(http.StatusOK)
+		_, _ = w.Write([]byte("ok"))
+	})
+
+	middleware := server.MirrorMiddleware(handler)
+
+	// Simulate a mirror request by adding the X-Mirror-Request header.
+	// This is what performMirror adds to the proxied request.
+	req := httptest.NewRequest("GET", "/loop", nil)
+	req.Header.Set("X-Mirror-Request", "true")
+	w := httptest.NewRecorder()
+
+	middleware.ServeHTTP(w, req)
+
+	// If the fix is working, the middleware should see X-Mirror-Request and
+	// pass directly to the handler WITHOUT trying to mirror again.
+	if callCount != 1 {
+		t.Errorf("Expected 1 call to handler, got %d", callCount)
+	}
+
+	if w.Code != http.StatusOK {
+		t.Errorf("Expected status 200, got %d", w.Code)
+	}
+}

pkg/service/handlers/mirror_middleware.go

@@ -27,8 +27,9 @@ import (
 func (s *Server) MirrorMiddleware(next http.Handler) http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		enabled, endpoints, preferredSource := s.getMirrorSettings()
+		isMirrorRequest := r.Header.Get("X-Mirror-Request") == "true"
 
-		if !enabled || len(endpoints) == 0 || !s.shouldMirror(r.URL.Path, endpoints) {
+		if !enabled || isMirrorRequest || len(endpoints) == 0 || !s.shouldMirror(r.URL.Path, endpoints) {
 			next.ServeHTTP(w, r)
 			return
 		}