send multipart email with both html and plaintext by default, closes #22

bot/command.go

@@ -17,7 +17,6 @@ const (
 	commandHelp          = "help"
 	commandStop          = "stop"
 	commandSend          = "send"
-	commandSendHTML      = "send:html"
 	commandDKIM          = "dkim"
 	commandCatchAll      = botOptionCatchAll
 	commandUsers         = botOptionUsers
@@ -68,11 +67,6 @@ func (b *Bot) initCommands() commandList {
 			description: "Send email",
 			allowed:     b.allowSend,
 		},
-		{
-			key:         commandSendHTML,
-			description: "Send email, converting markdown to HTML",
-			allowed:     b.allowSend,
-		},
 		{allowed: b.allowOwner}, // delimiter
 		// options commands
 		{
@@ -273,9 +267,7 @@ func (b *Bot) handleCommand(ctx context.Context, evt *event.Event, commandSlice
 	case commandStop:
 		b.runStop(ctx)
 	case commandSend:
-		b.runSend(ctx, false)
+		b.runSend(ctx)
-	case commandSendHTML:
-		b.runSend(ctx, true)
 	case commandDKIM:
 		b.runDKIM(ctx, commandSlice)
 	case commandUsers:
@@ -386,30 +378,27 @@ func (b *Bot) sendHelp(ctx context.Context) {
 	b.SendNotice(ctx, evt.RoomID, msg.String())
 }
 
-func (b *Bot) runSend(ctx context.Context, html bool) {
+func (b *Bot) runSend(ctx context.Context) {
 	evt := eventFromContext(ctx)
 	if !b.allowSend(evt.Sender, evt.RoomID) {
 		return
 	}
-	subcommand := "send"
-	if html {
-		subcommand = "send:html"
-	}
 	commandSlice := b.parseCommand(evt.Content.AsMessage().Body, false)
 	to, subject, body, err := utils.ParseSend(commandSlice)
 	if err == utils.ErrInvalidArgs {
 		b.SendNotice(ctx, evt.RoomID, fmt.Sprintf(
 			"Usage:\n"+
 				"```\n"+
-				"%s %s someone@example.com\n"+
+				"%s send someone@example.com\n"+
 				"Subject goes here on a line of its own\n"+
 				"Email content goes here\n"+
 				"on as many lines\n"+
 				"as you want.\n"+
 				"```",
-			b.prefix, subcommand))
+			b.prefix))
 		return
 	}
+	htmlBody := format.RenderMarkdown(body, true, true).FormattedBody
 
 	cfg, err := b.getRoomSettings(evt.RoomID)
 	if err != nil {
@@ -432,11 +421,6 @@ func (b *Bot) runSend(ctx context.Context, html bool) {
 		}
 	}
 
-	var htmlBody string
-	if html {
-		htmlBody = format.RenderMarkdown(body, true, true).FormattedBody
-	}
-
 	b.lock(evt.RoomID.String())
 	defer b.unlock(evt.RoomID.String())
 
@@ -445,7 +429,7 @@ func (b *Bot) runSend(ctx context.Context, html bool) {
 	ID := utils.MessageID(evt.ID, domain)
 	for _, to := range tos {
 		email := utils.NewEmail(ID, "", " "+ID, subject, from, to, body, htmlBody, nil)
-		data := email.Compose(html, b.getBotSettings().DKIMPrivateKey())
+		data := email.Compose(b.getBotSettings().DKIMPrivateKey())
 		queued, err := b.Sendmail(evt.ID, from, to, data)
 		if queued {
 			b.log.Error("cannot send email: %v", err)

bot/email.go

@@ -179,7 +179,7 @@ func (b *Bot) SendEmailReply(ctx context.Context) {
 	meta.References = meta.References + " " + meta.MessageID
 	b.log.Debug("send email reply: %+v", meta)
 	email := utils.NewEmail(meta.MessageID, meta.InReplyTo, meta.References, meta.Subject, meta.From, meta.To, body, htmlBody, nil)
-	data := email.Compose(false, b.getBotSettings().DKIMPrivateKey())
+	data := email.Compose(b.getBotSettings().DKIMPrivateKey())
 
 	queued, err := b.Sendmail(evt.ID, meta.From, meta.To, data)
 	if queued {

smtp/session.go

@@ -156,7 +156,7 @@ func (s *outgoingSession) Data(r io.Reader) error {
 		eml.HTML,
 		files)
 
-	return s.sendmail(email.From, email.To, email.Compose(false, s.privkey))
+	return s.sendmail(email.From, email.To, email.Compose(s.privkey))
 }
 func (s *outgoingSession) Reset()        {}
 func (s *outgoingSession) Logout() error { return nil }

utils/email.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"github.com/emersion/go-msgauth/dkim"
+	"gitlab.com/etke.cc/go/secgen"
 	"maunium.net/go/mautrix/event"
 	"maunium.net/go/mautrix/format"
 	"maunium.net/go/mautrix/id"
@@ -141,19 +142,18 @@ func (e *Email) Content(threadID id.EventID, options *ContentOptions) *event.Con
 }
 
 // Compose converts the email object to a string (to be used for delivery via SMTP) and possibly DKIM-signs it
-func (e *Email) Compose(html bool, privkey string) string {
+func (e *Email) Compose(privkey string) string {
 	var data strings.Builder
 
 	domain := strings.SplitN(e.From, "@", 2)[1]
+	boundaryName := "postmoogle" + secgen.Password(32)
+	boundary := "--" + boundaryName
 
 	data.WriteString("MIME-Version: 1.0")
 	data.WriteString("\r\n")
 
-	if html {
+	data.WriteString("Content-Type: multipart/alternative; boundary=")
-		data.WriteString("Content-Type: text/html; charset=\"UTF-8\"")
+	data.WriteString(boundaryName)
-	} else {
-		data.WriteString("Content-Type: text/plain; charset=\"UTF-8\"")
-	}
 	data.WriteString("\r\n")
 
 	data.WriteString("Content-Transfer-Encoding: 8BIT")
@@ -190,14 +190,26 @@ func (e *Email) Compose(html bool, privkey string) string {
 	data.WriteString("Subject: ")
 	data.WriteString(e.Subject)
 	data.WriteString("\r\n")
-
 	data.WriteString("\r\n")
 
-	if html {
+	data.WriteString(boundary)
+	data.WriteString("\r\n")
+	data.WriteString("Content-Type: text/html; charset=\"UTF-8\"")
+	data.WriteString("\r\n")
 	data.WriteString(e.HTML)
-	} else {
+	data.WriteString("\r\n")
+	data.WriteString("\r\n")
+
+	data.WriteString(boundary)
+	data.WriteString("\r\n")
+	data.WriteString("Content-Type: text/plain; charset=\"UTF-8\"")
+	data.WriteString("\r\n")
 	data.WriteString(e.Text)
-	}
+	data.WriteString("\r\n")
+	data.WriteString("\r\n")
+
+	data.WriteString(boundary)
+	data.WriteString("--")
 	data.WriteString("\r\n")
 
 	return e.sign(domain, privkey, data)