1package smtpserver

2

3import (

4 "errors"

5 "io"

6)

7

8var errMessageTooLarge = errors.New("maximum message size exceeded")

9

10type limitWriter struct {

11 maxSize int64

12 w io.Writer

13 written int64

14}

15

16func (w *limitWriter) Write(buf []byte) (int, error) {

17 if w.written+int64(len(buf)) > w.maxSize {

18 return 0, errMessageTooLarge

19 }

20 n, err := w.w.Write(buf)

21 if n > 0 {

22 w.written += int64(n)

23 }

24 return n, err

25}

26