lib/email: set the Date and Message-ID on Message Pack

Calling Pack now set the Date header if its not exist, using the local
time;  and the message-id header if its not exist using the following
format:

	<epoch>.<random-8-chars>@<local-hostname>

The random-8-chars is Seed-ed from Epoch(), so does the boundary.

6 files changed, 139 insertions, 36 deletions

diff --git a/lib/email/email.go b/lib/email/email.go
index 89eb1ffc..00aa692d 100644
--- a/lib/email/email.go
+++ b/lib/email/email.go
@@ -4,7 +4,12 @@
 
 package email
 
-import "time"
+import (
+	"math/rand"
+	"time"
+
+	"github.com/shuLhan/share/lib/ascii"
+)
 
 const (
 	contentTypeMultipartAlternative = "multipart/alternative"
@@ -20,19 +25,25 @@ const (
 	lf byte = '\n'
 )
 
+var boundSeps = []byte{'-', '-'}
+
 // dateInUtc if set to true, the Date header will be set to UTC instead of
 // local time.
-// This variable is used to make test work on all zones.
+// This variable is used to make testing works on all zones.
 var dateInUtc bool
 
 //
 // Epoch return the UNIX timestamp in seconds.
 //
-// This variable is exported to allow function that use date and/or time can
+// This variable is exported to allow function that use time and math/rand can
 // be tested with fixed, predictable value.
 //
 var Epoch = func() int64 {
 	return time.Now().Unix()
 }
 
-var boundSeps = []byte{'-', '-'}
+// randomChars generate n random characters.
+func randomChars(n int) []byte {
+	rand.Seed(Epoch())
+	return ascii.Random([]byte(ascii.LettersNumber), n)
+}
diff --git a/lib/email/email_test.go b/lib/email/email_test.go
index c0ff81ea..2c4e5fbd 100644
--- a/lib/email/email_test.go
+++ b/lib/email/email_test.go
@@ -9,6 +9,7 @@ import (
 	"crypto/x509"
 	"encoding/pem"
 	"io/ioutil"
+	"os"
 	"testing"
 	"time"
 
@@ -20,6 +21,14 @@ var (
 	publicKey  *rsa.PublicKey
 )
 
+func TestMain(m *testing.M) {
+	Epoch = func() int64 {
+		return 1645811431
+	}
+
+	os.Exit(m.Run())
+}
+
 func initKeys(t *testing.T) {
 	rsaPrivateRaw, err := ioutil.ReadFile("dkim/testdata/rsa.private.pem")
 	if err != nil {
diff --git a/lib/email/header.go b/lib/email/header.go
index d16030be..97a2992c 100644
--- a/lib/email/header.go
+++ b/lib/email/header.go
@@ -9,8 +9,6 @@ import (
 	"fmt"
 	"io"
 	"log"
-
-	"github.com/shuLhan/share/lib/ascii"
 )
 
 //
@@ -274,7 +272,7 @@ func (hdr *Header) SetMultipart() (err error) {
 		return fmt.Errorf("email.SetMultipart: %w", err)
 	}
 
-	boundary := ascii.Random([]byte(ascii.Hexaletters), 32)
+	boundary := randomChars(32)
 	contentType := hdr.ContentType()
 	contentType.SetBoundary(boundary)
 
@@ -294,6 +292,8 @@ func (hdr *Header) WriteTo(w io.Writer) (n int, err error) {
 	for _, f = range hdr.fields {
 		if f.Type == FieldTypeContentType {
 			m, err = fmt.Fprintf(w, "%s: %s\r\n", f.Name, f.ContentType.String())
+		} else if f.Type == FieldTypeMessageID {
+			m, err = fmt.Fprintf(w, "%s: <%s>\r\n", f.Name, f.oriValue)
 		} else {
 			m, err = fmt.Fprintf(w, "%s: %s", f.Name, f.Value)
 		}
diff --git a/lib/email/message.go b/lib/email/message.go
index df6baf20..731b8bf8 100644
--- a/lib/email/message.go
+++ b/lib/email/message.go
@@ -9,6 +9,7 @@ import (
 	"crypto/rsa"
 	"fmt"
 	"io/ioutil"
+	"os"
 	"strings"
 	"time"
 
@@ -379,6 +380,18 @@ func (msg *Message) SetFrom(mailbox string) (err error) {
 }
 
 //
+// SetID set or replace the message-id header to id.
+// If the id is empty, nothing will changes.
+//
+func (msg *Message) SetID(id string) {
+	id = strings.TrimSpace(id)
+	if len(id) == 0 {
+		return
+	}
+	_ = msg.Header.Set(FieldTypeMessageID, []byte(id))
+}
+
+//
 // SetSubject set or replace the subject.
 // It will do nothing if the subject is empty.
 //
@@ -489,6 +502,12 @@ func (msg *Message) CanonHeader(subHeader *Header, dkimField *Field) []byte {
 //
 // Pack the message for sending.
 //
+// This method will set the Date header if its not exist, using the local
+// time;
+// and the message-id header if its not exist using the following format:
+//
+//	<epoch>.<random-8-chars>@<local-hostname>
+//
 // The message content type is automatically set based on the Body parts.
 // If the Body only contain text part, the generated content-type will be set
 // to text/plain.
@@ -498,17 +517,46 @@ func (msg *Message) CanonHeader(subHeader *Header, dkimField *Field) []byte {
 // set to multipart/alternative.
 //
 func (msg *Message) Pack() (out []byte, err error) {
+	// TODO: check from, to, subject.
+
 	var (
-		logp = "Pack"
+		logp    = "Pack"
+		timeNow = time.Unix(Epoch(), 0)
+
+		dateValue string
+		hostname  string
+		id        string
+		fields    []*Field
 	)
 
 	if len(msg.Body.Parts) == 0 {
 		return nil, fmt.Errorf("%s: empty body", logp)
 	}
 
-	// TODO: check date, from, to, subject.
+	fields = msg.Header.Filter(FieldTypeDate)
+	if len(fields) == 0 {
+		if dateInUtc {
+			dateValue = timeNow.UTC().Format(DateFormat)
+		} else {
+			dateValue = timeNow.Format(DateFormat)
+		}
+		err = msg.Header.Set(FieldTypeDate, []byte(dateValue))
+		if err != nil {
+			return nil, fmt.Errorf("%s: %w", logp, err)
+		}
+	}
+
+	fields = msg.Header.Filter(FieldTypeMessageID)
+	if len(fields) == 0 {
+		hostname, err = os.Hostname()
+		if err != nil {
+			return nil, fmt.Errorf("%s: %w", logp, err)
+		}
+		id = fmt.Sprintf("%d.%s@%s", timeNow.Unix(), randomChars(8), hostname)
+		msg.SetID(id)
+	}
 
-	if len(msg.Body.Parts) > 1 {
+	if len(msg.Body.Parts) >= 2 {
 		out, err = msg.packMultipartAlternative()
 		if err != nil {
 			return nil, fmt.Errorf("%s: %w", logp, err)
diff --git a/lib/email/message_test.go b/lib/email/message_test.go
index 599f9a98..7a52a0c2 100644
--- a/lib/email/message_test.go
+++ b/lib/email/message_test.go
@@ -6,7 +6,7 @@ package email
 
 import (
 	"io/ioutil"
-	"math/rand"
+	"os"
 	"testing"
 
 	"github.com/shuLhan/share/lib/email/dkim"
@@ -15,16 +15,18 @@ import (
 
 func TestNewMultipart(t *testing.T) {
 	var (
-		gotMsg *Message
-		msgb   []byte
-		err    error
+		gotMsg   *Message
+		hostname string
+		msgb     []byte
+		err      error
 	)
 
 	dateInUtc = true
-	Epoch = func() int64 {
-		return 1645811431
+
+	hostname, err = os.Hostname()
+	if err != nil {
+		t.Fatal(err)
 	}
-	rand.Seed(42)
 
 	cases := []struct {
 		expMsg string
@@ -45,21 +47,22 @@ func TestNewMultipart(t *testing.T) {
 			"to: d@e.f\r\n" +
 			"subject: test\r\n" +
 			"mime-version: 1.0\r\n" +
-			"content-type: multipart/alternative; boundary=1b4df158039f7cce49f0a64b0ea7b7dd\r\n" +
+			"content-type: multipart/alternative; boundary=bqOnpYF7Yw1N0jDpjM004riRyz7oPxD6\r\n" +
+			"message-id: <1645811431.bqOnpYF7@" + hostname + ">\r\n" +
 			"\r\n" +
-			"--1b4df158039f7cce49f0a64b0ea7b7dd\r\n" +
+			"--bqOnpYF7Yw1N0jDpjM004riRyz7oPxD6\r\n" +
 			"mime-version: 1.0\r\n" +
 			"content-type: text/plain; charset=\"utf-8\"\r\n" +
 			"content-transfer-encoding: quoted-printable\r\n" +
 			"\r\n" +
 			"This is plain text\r\n" +
-			"--1b4df158039f7cce49f0a64b0ea7b7dd\r\n" +
+			"--bqOnpYF7Yw1N0jDpjM004riRyz7oPxD6\r\n" +
 			"mime-version: 1.0\r\n" +
 			"content-type: text/html; charset=\"utf-8\"\r\n" +
 			"content-transfer-encoding: quoted-printable\r\n" +
 			"\r\n" +
 			"<b>This is body in HTML</b>\r\n" +
-			"--1b4df158039f7cce49f0a64b0ea7b7dd--\r\n",
+			"--bqOnpYF7Yw1N0jDpjM004riRyz7oPxD6--\r\n",
 	}}
 
 	for _, c := range cases {
@@ -326,16 +329,25 @@ func TestMessage_packSingle(t *testing.T) {
 	}
 
 	var (
-		msg   Message
-		err   error
-		cases []testCase
-		got   []byte
+		msg      Message
+		hostname string
+		err      error
+		cases    []testCase
+		got      []byte
 	)
 
+	dateInUtc = true
+	hostname, err = os.Hostname()
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	cases = []testCase{{
 		desc:     "With body text",
 		bodyText: []byte(`this is a body text`),
 		exp: "" +
+			"date: Fri, 25 Feb 2022 17:50:31 +0000\r\n" +
+			"message-id: <1645811431.bqOnpYF7@" + hostname + ">\r\n" +
 			"mime-version: 1.0\r\n" +
 			"content-type: text/plain; charset=\"utf-8\"\r\n" +
 			"content-transfer-encoding: quoted-printable\r\n" +
@@ -345,6 +357,8 @@ func TestMessage_packSingle(t *testing.T) {
 		desc:     "With body HTML",
 		bodyHtml: []byte(`<p>this is an HTML body</p>`),
 		exp: "" +
+			"date: Fri, 25 Feb 2022 17:50:31 +0000\r\n" +
+			"message-id: <1645811431.bqOnpYF7@" + hostname + ">\r\n" +
 			"mime-version: 1.0\r\n" +
 			"content-type: text/html; charset=\"utf-8\"\r\n" +
 			"content-transfer-encoding: quoted-printable\r\n" +
@@ -377,9 +391,18 @@ func TestMessage_packSingle(t *testing.T) {
 
 func TestMessage_SetBodyText(t *testing.T) {
 	var (
-		msg Message
-		err error
+		msg      Message
+		hostname string
+		err      error
 	)
+
+	dateInUtc = true
+
+	hostname, err = os.Hostname()
+	if err != nil {
+		t.Fatal(err)
+	}
+
 	cases := []struct {
 		desc    string
 		expMsg  string
@@ -388,6 +411,8 @@ func TestMessage_SetBodyText(t *testing.T) {
 		desc:    "With empty Body",
 		content: []byte("text body"),
 		expMsg: "" +
+			"date: Fri, 25 Feb 2022 17:50:31 +0000\r\n" +
+			"message-id: <1645811431.bqOnpYF7@" + hostname + ">\r\n" +
 			"mime-version: 1.0\r\n" +
 			"content-type: text/plain; charset=\"utf-8\"\r\n" +
 			"content-transfer-encoding: quoted-printable\r\n" +
@@ -397,6 +422,8 @@ func TestMessage_SetBodyText(t *testing.T) {
 		desc:    "With new text",
 		content: []byte("new text body"),
 		expMsg: "" +
+			"date: Fri, 25 Feb 2022 17:50:31 +0000\r\n" +
+			"message-id: <1645811431.bqOnpYF7@" + hostname + ">\r\n" +
 			"mime-version: 1.0\r\n" +
 			"content-type: text/plain; charset=\"utf-8\"\r\n" +
 			"content-transfer-encoding: quoted-printable\r\n" +
diff --git a/lib/smtp/mail_tx_example_test.go b/lib/smtp/mail_tx_example_test.go
index 33ebbee3..a4b6df0a 100644
--- a/lib/smtp/mail_tx_example_test.go
+++ b/lib/smtp/mail_tx_example_test.go
@@ -8,7 +8,7 @@ import (
 	"bytes"
 	"fmt"
 	"log"
-	"math/rand"
+	"os"
 	"regexp"
 	"time"
 
@@ -39,12 +39,12 @@ func ExampleNewMailTx() {
 		mboxes     []*email.Mailbox
 		msg        *email.Message
 		mailtx     *MailTx
+		reDate     *regexp.Regexp
+		hostname   string
 		data       []byte
 		err        error
 	)
 
-	rand.Seed(42)
-
 	mboxes, err = email.ParseMailboxes(toAddresses)
 	if err != nil {
 		log.Fatal(err)
@@ -75,15 +75,22 @@ func ExampleNewMailTx() {
 	fmt.Printf("Tx Recipients: %s\n", mailtx.Recipients)
 
 	// In order to make the example Output works, we need to replace all
-	// CRLF with LF and "date:" with the system timezone.
+	// CRLF with LF, "date:" with the system timezone, and message-id
+	// hostname with fixed "hostname".
 	data = bytes.ReplaceAll(mailtx.Data, []byte("\r\n"), []byte("\n"))
 
 	//fmt.Printf("timeNowUtc: %s\n", timeNowUtc)
 	//fmt.Printf("dateNowUtc: %s\n", dateNowUtc)
 
-	reDate := regexp.MustCompile(`^date: Wed(.*) \+....`)
+	reDate = regexp.MustCompile(`^date: Wed(.*) \+....`)
 	data = reDate.ReplaceAll(data, []byte(`date: `+dateNowUtc))
 
+	hostname, err = os.Hostname()
+	if err != nil {
+		log.Fatal(err)
+	}
+	data = bytes.Replace(data, []byte(hostname), []byte("hostname"), 1)
+
 	fmt.Printf("Tx Data:\n%s", data)
 	//Output:
 	//Tx From: Postmaster <postmaster@mail.example.com>
@@ -94,19 +101,20 @@ func ExampleNewMailTx() {
 	//to: John <john@example.com>, Jane <jane@example.com>
 	//subject: Example subject
 	//mime-version: 1.0
-	//content-type: multipart/alternative; boundary=1b4df158039f7cce49f0a64b0ea7b7dd
+	//content-type: multipart/alternative; boundary=QoqDPQfzDVkv5R49vrA78GmqPmlfmBHf
+	//message-id: <1645600000.QoqDPQfz@hostname>
 	//
-	//--1b4df158039f7cce49f0a64b0ea7b7dd
+	//--QoqDPQfzDVkv5R49vrA78GmqPmlfmBHf
 	//mime-version: 1.0
 	//content-type: text/plain; charset="utf-8"
 	//content-transfer-encoding: quoted-printable
 	//
 	//Email body as plain text
-	//--1b4df158039f7cce49f0a64b0ea7b7dd
+	//--QoqDPQfzDVkv5R49vrA78GmqPmlfmBHf
 	//mime-version: 1.0
 	//content-type: text/html; charset="utf-8"
 	//content-transfer-encoding: quoted-printable
 	//
 	//Email body as <b>HTML</b>
-	//--1b4df158039f7cce49f0a64b0ea7b7dd--
+	//--QoqDPQfzDVkv5R49vrA78GmqPmlfmBHf--
 }