1package imapserver

2

3import (

4 "bufio"

5 "io"

6 "net"

7)

8

9// prefixConn is a net.Conn with a buffer from which the first reads are satisfied.

10// used for STARTTLS where already did a buffered read of initial TLS data.

11type prefixConn struct {

12 prefix []byte

13 net.Conn

14}

15

16func (c *prefixConn) Read(buf []byte) (int, error) {

17 if len(c.prefix) > 0 {

18 n := len(buf)

19 if n > len(c.prefix) {

20 n = len(c.prefix)

21 }

22 copy(buf[:n], c.prefix[:n])

23 c.prefix = c.prefix[n:]

24 if len(c.prefix) == 0 {

25 c.prefix = nil

26 }

27 return n, nil

28 }

29 return c.Conn.Read(buf)

30}

31

32// xprefixConn returns either the original net.Conn passed as parameter, or returns

33// a *prefixConn returning the buffered data available in br followed data from the

34// net.Conn passed in.

35func xprefixConn(c net.Conn, br *bufio.Reader) net.Conn {

36 n := br.Buffered()

37 if n == 0 {

38 return c

39 }

40

41 buf := make([]byte, n)

42 _, err := io.ReadFull(c, buf)

43 xcheckf(err, "get buffered data")

44 return &prefixConn{buf, c}

45}

46