package koushin import ( "fmt" "io" "time" "github.com/emersion/go-message/mail" "github.com/emersion/go-smtp" ) func (s *Server) connectSMTP() (*smtp.Client, error) { var c *smtp.Client var err error if s.smtp.tls { c, err = smtp.DialTLS(s.smtp.host, nil) if err != nil { return nil, fmt.Errorf("failed to connect to SMTPS server: %v", err) } } else { c, err = smtp.Dial(s.smtp.host) if err != nil { return nil, fmt.Errorf("failed to connect to SMTP server: %v", err) } if !s.smtp.insecure { if err := c.StartTLS(nil); err != nil { c.Close() return nil, fmt.Errorf("STARTTLS failed: %v", err) } } } return c, err } type OutgoingMessage struct { From string To []string Subject string Text string } func (msg *OutgoingMessage) WriteTo(w io.Writer) error { from := []*mail.Address{{"", msg.From}} to := make([]*mail.Address, len(msg.To)) for i, addr := range msg.To { to[i] = &mail.Address{"", addr} } var h mail.Header h.SetDate(time.Now()) h.SetAddressList("From", from) h.SetAddressList("To", to) if msg.Subject != "" { h.SetText("Subject", msg.Subject) } mw, err := mail.CreateWriter(w, h) if err != nil { return fmt.Errorf("failed to create mail writer: %v", err) } var th mail.InlineHeader th.Set("Content-Type", "text/plain; charset=utf-8") tw, err := mw.CreateSingleInline(th) if err != nil { return fmt.Errorf("failed to create text part: %v", err) } defer tw.Close() if _, err := io.WriteString(tw, msg.Text); err != nil { return fmt.Errorf("failed to write text part: %v", err) } if err := tw.Close(); err != nil { return fmt.Errorf("failed to close text part: %v", err) } if err := mw.Close(); err != nil { return fmt.Errorf("failed to close mail writer: %v", err) } return nil } func sendMessage(c *smtp.Client, msg *OutgoingMessage) error { if err := c.Mail(msg.From, nil); err != nil { return fmt.Errorf("MAIL FROM failed: %v", err) } for _, to := range msg.To { if err := c.Rcpt(to); err != nil { return fmt.Errorf("RCPT TO failed: %v", err) } } w, err := c.Data() if err != nil { return fmt.Errorf("DATA failed: %v", err) } defer w.Close() if err := msg.WriteTo(w); err != nil { return fmt.Errorf("failed to write outgoing message: %v", err) } if err := w.Close(); err != nil { return fmt.Errorf("failed to close SMTP data writer: %v", err) } return nil }