Limit Size Of Objects While Uploading To Amazon S3 Using Pre-Signed URL

Question

I know of limiting the upload size of an object using this method: http://doc.s3.amazonaws.com/proposals/post.html#Limiting_Uploaded_Content

But i would like to know how it can be done while generating a pre-signed url using S3 SDK on the server side as an IAM user.

This Url from SDK has no such option in its parameters : http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#putObject-property

Neither in this: http://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#getSignedUrl-property

Please note: I already know of this answer: AWS S3 Pre-signed URL content-length and it is NOT what i am looking for.

question from:https://stackoverflow.com/questions/25991275/limit-size-of-objects-while-uploading-to-amazon-s3-using-pre-signed-url

Answer 1

The V4 signing protocol offers the option to include arbitrary headers in the signature. See: http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-query-string-auth.html So, if you know the exact Content-Length in advance, you can include that in the signed URL. Based on some experiments with CURL, S3 will truncate the file if you send more than specified in the Content-Length header. Here is an example V4 signature with multiple headers in the signature http://docs.aws.amazon.com/general/latest/gr/sigv4-add-signature-to-request.html