1package config

2

3import (

4 "errors"

5 "fmt"

6 "strings"

7

8 "golang.org/x/text/unicode/norm"

9)

10

11// CheckMailboxName checks if name is valid, returning an INBOX-normalized name.

12func CheckMailboxName(name string, allowInbox bool) (normalizedName string, isInbox bool, rerr error) {

13 t := strings.Split(name, "/")

14 if strings.EqualFold(t[0], "inbox") {

15 if len(name) == len("inbox") && !allowInbox {

16 return "", true, fmt.Errorf("special mailbox name Inbox not allowed")

17 }

18 name = "Inbox" + name[len("Inbox"):]

19 }

20

21 if norm.NFC.String(name) != name {

22 return "", false, errors.New("non-unicode-normalized mailbox names not allowed")

23 }

24

25 for _, e := range t {

26 switch e {

27 case "":

28 return "", false, errors.New("empty mailbox name")

29 case ".":

30 return "", false, errors.New(`"." not allowed`)

31 case "..":

32 return "", false, errors.New(`".." not allowed`)

33 }

34 }

35 if strings.HasPrefix(name, "/") || strings.HasSuffix(name, "/") || strings.Contains(name, "//") {

36 return "", false, errors.New("bad slashes in mailbox name")

37 }

38

39 // "%" and "*" are difficult to use with the IMAP LIST command, but we allow mostly

40 // allow them. ../rfc/3501:1002 ../rfc/9051:983

41 if strings.HasPrefix(name, "#") {

42 return "", false, errors.New("mailbox name cannot start with hash due to conflict with imap namespaces")

43 }

44

45 // "#" and "&" are special in IMAP mailbox names. "#" for namespaces, "&" for

46 // IMAP-UTF-7 encoding. We do allow them. ../rfc/3501:1018 ../rfc/9051:991

47

48 for _, c := range name {

49 // ../rfc/3501:999 ../rfc/6855:192 ../rfc/9051:979

50 if c <= 0x1f || c >= 0x7f && c <= 0x9f || c == 0x2028 || c == 0x2029 {

51 return "", false, errors.New("control characters not allowed in mailbox name")

52 }

53 }

54 return name, false, nil

55}

56