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// SPDX-License-Identifier: AGPL-3.0-only
// SPDX-FileCopyrightText: Copyright (c) 2025 Runxi Yu <https://runxiyu.org>
package unsorted
import (
"context"
"crypto/tls"
"errors"
"fmt"
"log/slog"
"net"
stdsmtp "net/smtp"
"time"
"github.com/emersion/go-sasl"
"github.com/emersion/go-smtp"
)
// relayMailingListMessage connects to the configured SMTP relay and sends the
// raw message to all subscribers of the given list. The message is written verbatim
// from this point on and there is no modification of any headers or whatever,
func (s *Server) relayMailingListMessage(ctx context.Context, listID int, envelopeFrom string, raw []byte) error {
rows, err := s.database.Query(ctx, `SELECT email FROM mailing_list_subscribers WHERE list_id = $1`, listID)
if err != nil {
return err
}
defer rows.Close()
var recipients []string
for rows.Next() {
var email string
if err = rows.Scan(&email); err != nil {
return err
}
recipients = append(recipients, email)
}
if err = rows.Err(); err != nil {
return err
}
if len(recipients) == 0 {
slog.Info("mailing list has no subscribers", "list_id", listID)
return nil
}
netw := s.config.SMTP.Net
if netw == "" {
netw = "tcp"
}
if s.config.SMTP.Addr == "" {
return errors.New("smtp relay addr not configured")
}
helloName := s.config.SMTP.HelloName
if helloName == "" {
helloName = s.config.LMTP.Domain
}
transport := s.config.SMTP.Transport
if transport == "" {
transport = "plain"
}
switch transport {
case "plain", "tls":
d := net.Dialer{Timeout: 30 * time.Second}
var conn net.Conn
var err error
if transport == "tls" {
tlsCfg := &tls.Config{ServerName: hostFromAddr(s.config.SMTP.Addr), InsecureSkipVerify: s.config.SMTP.TLSInsecure}
conn, err = tls.DialWithDialer(&d, netw, s.config.SMTP.Addr, tlsCfg)
} else {
conn, err = d.DialContext(ctx, netw, s.config.SMTP.Addr)
}
if err != nil {
return fmt.Errorf("dial smtp: %w", err)
}
defer conn.Close()
c := smtp.NewClient(conn)
defer c.Close()
if err := c.Hello(helloName); err != nil {
return fmt.Errorf("smtp hello: %w", err)
}
if s.config.SMTP.Username != "" {
mech := sasl.NewPlainClient("", s.config.SMTP.Username, s.config.SMTP.Password)
if err := c.Auth(mech); err != nil {
return fmt.Errorf("smtp auth: %w", err)
}
}
if err := c.Mail(envelopeFrom, &smtp.MailOptions{}); err != nil {
return fmt.Errorf("smtp mail from: %w", err)
}
for _, rcpt := range recipients {
if err := c.Rcpt(rcpt, &smtp.RcptOptions{}); err != nil {
return fmt.Errorf("smtp rcpt %s: %w", rcpt, err)
}
}
wc, err := c.Data()
if err != nil {
return fmt.Errorf("smtp data: %w", err)
}
if _, err := wc.Write(raw); err != nil {
_ = wc.Close()
return fmt.Errorf("smtp write: %w", err)
}
if err := wc.Close(); err != nil {
return fmt.Errorf("smtp data close: %w", err)
}
if err := c.Quit(); err != nil {
return fmt.Errorf("smtp quit: %w", err)
}
return nil
case "starttls":
d := net.Dialer{Timeout: 30 * time.Second}
conn, err := d.DialContext(ctx, netw, s.config.SMTP.Addr)
if err != nil {
return fmt.Errorf("dial smtp: %w", err)
}
defer conn.Close()
host := hostFromAddr(s.config.SMTP.Addr)
c, err := stdsmtp.NewClient(conn, host)
if err != nil {
return fmt.Errorf("smtp new client: %w", err)
}
defer c.Close()
if err := c.Hello(helloName); err != nil {
return fmt.Errorf("smtp hello: %w", err)
}
if ok, _ := c.Extension("STARTTLS"); !ok {
return errors.New("smtp server does not support STARTTLS")
}
tlsCfg := &tls.Config{ServerName: host, InsecureSkipVerify: s.config.SMTP.TLSInsecure} // #nosec G402
if err := c.StartTLS(tlsCfg); err != nil {
return fmt.Errorf("starttls: %w", err)
}
// seems like ehlo is required after starttls
if err := c.Hello(helloName); err != nil {
return fmt.Errorf("smtp hello (post-starttls): %w", err)
}
if s.config.SMTP.Username != "" {
auth := stdsmtp.PlainAuth("", s.config.SMTP.Username, s.config.SMTP.Password, host)
if err := c.Auth(auth); err != nil {
return fmt.Errorf("smtp auth: %w", err)
}
}
if err := c.Mail(envelopeFrom); err != nil {
return fmt.Errorf("smtp mail from: %w", err)
}
for _, rcpt := range recipients {
if err := c.Rcpt(rcpt); err != nil {
return fmt.Errorf("smtp rcpt %s: %w", rcpt, err)
}
}
wc, err := c.Data()
if err != nil {
return fmt.Errorf("smtp data: %w", err)
}
if _, err := wc.Write(raw); err != nil {
_ = wc.Close()
return fmt.Errorf("smtp write: %w", err)
}
if err := wc.Close(); err != nil {
return fmt.Errorf("smtp data close: %w", err)
}
if err := c.Quit(); err != nil {
return fmt.Errorf("smtp quit: %w", err)
}
return nil
default:
return fmt.Errorf("unknown smtp transport: %q", transport)
}
}
func hostFromAddr(addr string) string {
host, _, err := net.SplitHostPort(addr)
if err != nil || host == "" {
return addr
}
return host
}
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