1package message

2

3import (

4 "fmt"

5 "io"

6 "net/textproto"

7

8 "github.com/mjl-/mox/dns"

9 "github.com/mjl-/mox/mlog"

10 "github.com/mjl-/mox/smtp"

11)

12

13// From extracts the address in the From-header.

14//

15// An RFC5322 message must have a From header.

16// In theory, multiple addresses may be present. In practice zero or multiple

17// From headers may be present. From returns an error if there is not exactly

18// one address. This address can be used for evaluating a DMARC policy against

19// SPF and DKIM results.

20func From(log *mlog.Log, strict bool, r io.ReaderAt) (raddr smtp.Address, header textproto.MIMEHeader, rerr error) {

21 // ../rfc/7489:1243

22

23 // todo: only allow utf8 if enabled in session/message?

24

25 p, err := Parse(log, strict, r)

26 if err != nil {

27 // todo: should we continue with p, perhaps headers can be parsed?

28 return raddr, nil, fmt.Errorf("parsing message: %v", err)

29 }

30 header, err = p.Header()

31 if err != nil {

32 return raddr, nil, fmt.Errorf("parsing message header: %v", err)

33 }

34 from := p.Envelope.From

35 if len(from) != 1 {

36 return raddr, nil, fmt.Errorf("from header has %d addresses, need exactly 1 address", len(from))

37 }

38 d, err := dns.ParseDomain(from[0].Host)

39 if err != nil {

40 return raddr, nil, fmt.Errorf("bad domain in from address: %v", err)

41 }

42 addr := smtp.Address{Localpart: smtp.Localpart(from[0].User), Domain: d}

43 return addr, textproto.MIMEHeader(header), nil

44}

45