1 package http 2 3 import ( 4 "crypto/md5" 5 "encoding/base64" 6 "fmt" 7 "io" 8 ) 9 10 // computeMD5Checksum computes base64 md5 checksum of an io.Reader's contents. 11 // Returns the byte slice of md5 checksum and an error. 12 func computeMD5Checksum(r io.Reader) ([]byte, error) { 13 h := md5.New() 14 // copy errors may be assumed to be from the body. 15 _, err := io.Copy(h, r) 16 if err != nil { 17 return nil, fmt.Errorf("failed to read body: %w", err) 18 } 19 20 // encode the md5 checksum in base64. 21 sum := h.Sum(nil) 22 sum64 := make([]byte, base64.StdEncoding.EncodedLen(len(sum))) 23 base64.StdEncoding.Encode(sum64, sum) 24 return sum64, nil 25 } 26