package s3 import ( "crypto/md5" "encoding/base64" "io" "github.com/aws/aws-sdk-go/aws" "github.com/aws/aws-sdk-go/aws/awserr" ) // contentMD5 computes and sets the HTTP Content-MD5 header for requests that // require it. func contentMD5(r *aws.Request) { h := md5.New() // hash the body. seek back to the first position after reading to reset // the body for transmission. copy errors may be assumed to be from the // body. _, err := io.Copy(h, r.Body) if err != nil { r.Error = awserr.New("ContentMD5", "failed to read body", err) return } _, err = r.Body.Seek(0, 0) if err != nil { r.Error = awserr.New("ContentMD5", "failed to seek body", err) return } // encode the md5 checksum in base64 and set the request header. sum := h.Sum(nil) sum64 := make([]byte, base64.StdEncoding.EncodedLen(len(sum))) base64.StdEncoding.Encode(sum64, sum) r.HTTPRequest.Header.Set("Content-MD5", string(sum64)) }