1package http
 2
 3import (
 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.
12func 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}