proxy: Preserve query string when forwarding to upstream mirrors

The upstream URL was constructed with only Scheme, Host, and Path,
dropping any query parameters from the original client request. Add
RawQuery to the upstream URL so query strings are forwarded correctly.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: ganto

pkg/pkgproxy/proxy.go

@@ -314,9 +314,10 @@ func (pp *pkgProxy) tryMirrors(ctx context.Context, rid string, req *http.Reques
 
 			upstreamPath := path.Join(mirror.Path, strings.TrimPrefix(req.URL.Path, "/"+repo))
 			rsp, err = pp.forwardClientRequestToOrigin(ctx, rid, req, &url.URL{
-				Scheme: mirror.Scheme,
-				Host:   mirror.Host,
-				Path:   upstreamPath,
+				Scheme:   mirror.Scheme,
+				Host:     mirror.Host,
+				Path:     upstreamPath,
+				RawQuery: req.URL.RawQuery,
 			}, reqBody)
 			if err != nil {
 				slog.Warn("upstream request failed", "request_id", rid, "mirror_index", i, "attempt", attempt, "error", err)

pkg/pkgproxy/proxy_test.go

@@ -587,6 +587,25 @@ func TestForwardProxyUpstreamPath(t *testing.T) {
 	assert.Equal(t, "/basepath/sub/dir/file.rpm", receivedPath)
 }
 
+func TestForwardProxyQueryStringPreserved(t *testing.T) {
+	var receivedRawQuery string
+	upstream := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		receivedRawQuery = r.URL.RawQuery
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer upstream.Close()
+
+	pp, _ := newTestProxy(t, []string{upstream.URL + "/"})
+	app := newTestApp(pp)
+
+	req := httptest.NewRequest(http.MethodGet, "/testrepo/repodata/repomd.xml?age=300&arch=x86_64", nil)
+	rec := httptest.NewRecorder()
+	app.ServeHTTP(rec, req)
+
+	assert.Equal(t, http.StatusOK, rec.Code)
+	assert.Equal(t, "age=300&arch=x86_64", receivedRawQuery)
+}
+
 // --- httpbin.org tests (gated by environment variable) ---
 
 func TestForwardProxyWithHttpbin(t *testing.T) {