从闪存上传文件时如何获取Content-Type - 是否可能？

we have a small flash component on our website/application to upload multiple files. This works fine, however we want to get the Content-Type from the headers and its always set to 'application/octet-stream'. From what I've learned this is due to a security of flash sandbox and FileUpLoad will never give this to us.we have a small flash component on our website/