1package dmarc_test

2

3import (

4 "context"

5 "log"

6 "log/slog"

7 "net"

8 "strings"

9

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

11 "github.com/mjl-/mox/dmarc"

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

13 "github.com/mjl-/mox/message"

14 "github.com/mjl-/mox/spf"

15)

16

17func ExampleLookup() {

18 ctx := context.Background()

19 resolver := dns.StrictResolver{}

20 msgFrom, err := dns.ParseDomain("sub.example.com")

21 if err != nil {

22 log.Fatalf("parsing from domain: %v", err)

23 }

24

25 // Lookup DMARC DNS record for domain.

26 status, domain, record, txt, authentic, err := dmarc.Lookup(ctx, slog.Default(), resolver, msgFrom)

27 if err != nil {

28 log.Fatalf("dmarc lookup: %v", err)

29 }

30

31 log.Printf("status %s, domain %s, record %v, txt %q, dnssec %v", status, domain, record, txt, authentic)

32}

33

34func ExampleVerify() {

35 ctx := context.Background()

36 resolver := dns.StrictResolver{}

37

38 // Message to verify.

39 msg := strings.NewReader("From: <sender@example.com>\r\nMore: headers\r\n\r\nBody\r\n")

40 msgFrom, _, _, err := message.From(slog.Default(), true, msg, nil)

41 if err != nil {

42 log.Fatalf("parsing message for from header: %v", err)

43 }

44

45 // Verify SPF, for use with DMARC.

46 args := spf.Args{

47 RemoteIP: net.ParseIP("10.11.12.13"),

48 MailFromDomain: dns.Domain{ASCII: "sub.example.com"},

49 }

50 spfReceived, spfDomain, _, _, err := spf.Verify(ctx, slog.Default(), resolver, args)

51 if err != nil {

52 log.Printf("verifying spf: %v", err)

53 }

54

55 // Verify DKIM-Signature headers, for use with DMARC.

56 smtputf8 := false

57 ignoreTestMode := false

58 dkimResults, err := dkim.Verify(ctx, slog.Default(), resolver, smtputf8, dkim.DefaultPolicy, msg, ignoreTestMode)

59 if err != nil {

60 log.Printf("verifying dkim: %v", err)

61 }

62

63 // Verify DMARC, based on DKIM and SPF results.

64 applyRandomPercentage := true

65 useResult, result := dmarc.Verify(ctx, slog.Default(), resolver, msgFrom.Domain, dkimResults, spfReceived.Result, &spfDomain, applyRandomPercentage)

66

67 // Print results.

68 log.Printf("dmarc status: %s", result.Status)

69 log.Printf("use result: %v", useResult)

70 if useResult && result.Reject {

71 log.Printf("should reject message")

72 }

73 log.Printf("result: %#v", result)

74}

75

76func ExampleParseRecord() {

77 txt := "v=DMARC1; p=reject; rua=mailto:postmaster@mox.example"

78

79 record, isdmarc, err := dmarc.ParseRecord(txt)

80 if err != nil {

81 log.Fatalf("parsing dmarc record: %v (isdmarc: %v)", err, isdmarc)

82 }

83

84 log.Printf("parsed record: %v", record)

85}

86