fix(crypt): add sign to thumbnail (#6611)

server/common/common.go

@@ -1,6 +1,8 @@
 package common
 
 import (
+	"context"
+	"net/http"
 	"strings"
 
 	"github.com/alist-org/alist/v3/cmd/flags"
@@ -80,3 +82,10 @@ func SuccessResp(c *gin.Context, data ...interface{}) {
 		Data:    data[0],
 	})
 }
+
+func GetHttpReq(ctx context.Context) *http.Request {
+	if c, ok := ctx.(*gin.Context); ok {
+		return c.Request
+	}
+	return nil
+}