fix: verify OSS objects before serving

server/media/oss/oss_tenant_test.go

@@ -1,9 +1,12 @@
 package oss
 
 import (
+	"net/http"
 	"testing"
 	"time"
 
+	aliyunoss "github.com/aliyun/aliyun-oss-go-sdk/oss"
+
 	"github.com/tinode/chat/server/store"
 	"github.com/tinode/chat/server/store/types"
 )
@@ -46,6 +49,15 @@ func TestGetIdFromUrl(t *testing.T) {
 	}
 }
 
+func TestIsOSSObjectNotFound(t *testing.T) {
+	if !isOSSObjectNotFound(aliyunoss.ServiceError{StatusCode: http.StatusNotFound, Code: "NoSuchKey"}) {
+		t.Fatal("NoSuchKey should be treated as missing object")
+	}
+	if isOSSObjectNotFound(aliyunoss.ServiceError{StatusCode: http.StatusForbidden, Code: "AccessDenied"}) {
+		t.Fatal("AccessDenied must not be treated as missing object")
+	}
+}
+
 func TestLoadSysConfig(t *testing.T) {
 	original := store.ThirdPartyConfig
 	store.ThirdPartyConfig = fakeThirdPartyConfig{