feat: add personal mailbox forwarding

2026-08-02 07:37:07 +08:00
parent 77a0fd254c
commit 7f05a70f60
11 changed files with 683 additions and 46 deletions
@@ -0,0 +1,153 @@
+package app
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"os"
+	"strings"
+)
+
+const forwardingHeaderName = "X-LanQin-Forwarded-By"
+
+func (a *App) processInboundForwarding(ctx context.Context, messageID, mailboxID string, raw []byte) {
+	target, userID, mailboxAddress, err := a.inboundForwardingTarget(ctx, mailboxID)
+	if err != nil {
+		a.log.Warn("failed to load forwarding target", "message", messageID, "mailbox", mailboxID, "error", err)
+		return
+	}
+	if target == "" || userID == "" || mailboxAddress == "" {
+		return
+	}
+	if normalizeEmail(target) == normalizeEmail(mailboxAddress) {
+		return
+	}
+	if len(raw) == 0 {
+		raw, err = a.forwardingRawMessage(ctx, messageID)
+		if err != nil {
+			a.log.Warn("failed to load raw message for forwarding", "message", messageID, "error", err)
+			return
+		}
+	}
+	if hasForwardingHeader(raw) {
+		a.log.Warn("skip forwarding message that already has LanQin forwarding header", "message", messageID, "mailbox", mailboxID)
+		return
+	}
+	forwarded := addForwardingHeaders(raw, mailboxAddress, a.cfg.PublicHostname)
+	var rfcMessageID string
+	_ = a.db.QueryRowContext(ctx, `SELECT message_id FROM messages WHERE id=?`, messageID).Scan(&rfcMessageID)
+	if strings.TrimSpace(rfcMessageID) == "" {
+		rfcMessageID = messageID
+	}
+	queueID, err := a.enqueueSend(ctx, sendQueueInput{
+		UserID:        userID,
+		MailboxID:     mailboxID,
+		SentMessageID: messageID,
+		MessageID:     rfcMessageID,
+		Source:        sendSourceForwarding,
+		MailFrom:      mailboxAddress,
+		HeaderFrom:    mailboxAddress,
+		Recipients:    []string{target},
+		MIMEBytes:     forwarded,
+		Now:           a.now().UTC(),
+	})
+	if err != nil {
+		a.log.Warn("failed to enqueue inbound forwarding", "message", messageID, "mailbox", mailboxID, "target", target, "error", err)
+		return
+	}
+	if queueID == "" {
+		a.log.Warn("forwarding target configured but SMTP sending is not configured", "message", messageID, "mailbox", mailboxID, "target", target)
+	}
+}
+
+func (a *App) inboundForwardingTarget(ctx context.Context, mailboxID string) (targetEmail, userID, mailboxAddress string, err error) {
+	var mailboxTarget, accountTarget string
+	err = a.db.QueryRowContext(ctx, `SELECT mb.user_id,mb.address,COALESCE(mfs.target_email,''),COALESCE(afs.target_email,'')
+		FROM mailboxes mb
+		LEFT JOIN mailbox_forwarding_settings mfs ON mfs.mailbox_id=mb.id
+		LEFT JOIN account_forwarding_settings afs ON afs.user_id=mb.user_id
+		WHERE mb.id=? AND mb.status='active'`, mailboxID).Scan(&userID, &mailboxAddress, &mailboxTarget, &accountTarget)
+	if err != nil {
+		return "", "", "", err
+	}
+	target := normalizeEmail(mailboxTarget)
+	if target == "" {
+		target = normalizeEmail(accountTarget)
+	}
+	if target == "" {
+		return "", userID, mailboxAddress, nil
+	}
+	verified, err := a.forwardingEmailVerified(ctx, userID, target)
+	if err != nil {
+		return "", "", "", err
+	}
+	if !verified {
+		return "", userID, mailboxAddress, nil
+	}
+	return target, userID, mailboxAddress, nil
+}
+
+func (a *App) forwardingRawMessage(ctx context.Context, messageID string) ([]byte, error) {
+	msg, err := a.storedMessageByID(ctx, messageID)
+	if err != nil {
+		return nil, err
+	}
+	if strings.TrimSpace(msg.RawPath) != "" {
+		if ok, err := a.pathIsUnderMaildirRoot(msg.RawPath); err == nil && ok {
+			if raw, err := os.ReadFile(msg.RawPath); err == nil {
+				return raw, nil
+			}
+		}
+	}
+	attachments, err := a.attachmentInputsForMessage(ctx, messageID)
+	if err != nil {
+		return nil, err
+	}
+	return BuildMIME(MIMEMessage{
+		From:        msg.From,
+		FromName:    msg.FromName,
+		To:          msg.To,
+		CC:          msg.CC,
+		BCC:         msg.BCC,
+		Subject:     msg.Subject,
+		Text:        msg.BodyText,
+		HTML:        msg.BodyHTML,
+		MessageID:   msg.MessageID,
+		Date:        messageDate(msg),
+		Attachments: attachments,
+	})
+}
+
+func hasForwardingHeader(raw []byte) bool {
+	header := raw
+	if idx := bytes.Index(raw, []byte("\r\n\r\n")); idx >= 0 {
+		header = raw[:idx]
+	} else if idx := bytes.Index(raw, []byte("\n\n")); idx >= 0 {
+		header = raw[:idx]
+	}
+	return strings.Contains(strings.ToLower(string(header)), strings.ToLower(forwardingHeaderName)+":")
+}
+
+func addForwardingHeaders(raw []byte, mailboxAddress, hostname string) []byte {
+	hostname = strings.TrimSpace(hostname)
+	if hostname == "" {
+		hostname = "lanqin.local"
+	}
+	header := fmt.Sprintf("%s: %s\r\nX-LanQin-Forwarded-For: %s\r\n", forwardingHeaderName, hostname, normalizeEmail(mailboxAddress))
+	if idx := bytes.Index(raw, []byte("\r\n\r\n")); idx >= 0 {
+		out := make([]byte, 0, len(raw)+len(header))
+		out = append(out, raw[:idx]...)
+		out = append(out, []byte("\r\n"+header)...)
+		out = append(out, raw[idx+2:]...)
+		return out
+	}
+	if idx := bytes.Index(raw, []byte("\n\n")); idx >= 0 {
+		lfHeader := strings.ReplaceAll(header, "\r\n", "\n")
+		out := make([]byte, 0, len(raw)+len(lfHeader))
+		out = append(out, raw[:idx]...)
+		out = append(out, []byte("\n"+lfHeader)...)
+		out = append(out, raw[idx+1:]...)
+		return out
+	}
+	return append([]byte(header+"\r\n"), raw...)
+}