130 lines
3.0 KiB
Go
130 lines
3.0 KiB
Go
package mailer
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import (
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"bytes"
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"crypto/tls"
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"crypto/x509"
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"errors"
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"fmt"
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"github.com/emersion/go-message"
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"github.com/emersion/go-sasl"
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"github.com/emersion/go-smtp"
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"io"
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"os"
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"strings"
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)
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type Mailer struct {
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auth sasl.Client
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conf SmtpConfig
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pool *x509.CertPool
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}
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func NewMailer(conf SmtpConfig) (*Mailer, error) {
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var pool *x509.CertPool = nil
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if conf.Cert != "" {
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pool = x509.NewCertPool()
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open, err := os.Open(conf.Cert)
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if err != nil {
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return nil, err
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}
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all, err := io.ReadAll(open)
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if err != nil {
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return nil, err
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}
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if !pool.AppendCertsFromPEM(all) {
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return nil, errors.New("invalid SMTP certificate")
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}
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}
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return &Mailer{
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auth: sasl.NewPlainClient("", conf.Username, conf.Password),
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conf: conf,
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pool: pool,
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}, nil
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}
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func (m *Mailer) MailHtml(subject string, to []string, body io.Reader) error {
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h := message.Header{}
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h.SetContentType("multipart/alternative", nil)
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h.SetText("From", m.conf.From)
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h.SetText("To", strings.Join(to, ", "))
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h.SetText("Subject", subject)
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h.SetText("MIME-version", "1.0")
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msg := new(bytes.Buffer)
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w, err := message.CreateWriter(msg, h)
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if err != nil {
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return fmt.Errorf("failed to create message writer: %w", err)
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}
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h2 := message.Header{}
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h2.SetContentType("text/html", map[string]string{"charset": "UTF-8"})
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part, err := w.CreatePart(h2)
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if err != nil {
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return fmt.Errorf("failed to create part: %w", err)
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}
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_, err = io.Copy(part, body)
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if err != nil {
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return fmt.Errorf("failed to copy body into part: %w", err)
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}
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err = part.Close()
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if err != nil {
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return fmt.Errorf("failed to close part: %w", err)
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}
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err = w.Close()
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if err != nil {
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return fmt.Errorf("failed to close message writer: %w", err)
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}
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return m.sendMail(to, msg)
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}
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func (m *Mailer) sendMail(to []string, body io.Reader) error {
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var err error
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var client *smtp.Client
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if m.conf.Tls {
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client, err = smtp.DialTLS(m.conf.Server, &tls.Config{RootCAs: m.pool})
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if err != nil {
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return fmt.Errorf("failed to dial tls: %w", err)
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}
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} else {
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client, err = smtp.Dial(m.conf.Server)
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if err != nil {
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return fmt.Errorf("failed to dial: %w", err)
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}
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}
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if m.conf.StartTls {
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if ok, _ := client.Extension("STARTTLS"); ok {
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if err = client.StartTLS(nil); err != nil {
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return fmt.Errorf("failed to start tls: %w", err)
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}
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}
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}
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if err = client.Auth(m.auth); err != nil {
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return fmt.Errorf("failed to add auth: %w", err)
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}
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if err = client.Mail(m.conf.Username, nil); err != nil {
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return fmt.Errorf("failed to start mail: %w", err)
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}
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for _, i := range to {
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if err = client.Rcpt(i); err != nil {
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return fmt.Errorf("failed to add recipient: %w", err)
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}
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}
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wc, err := client.Data()
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if err != nil {
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return fmt.Errorf("failed to start mail data: %w", err)
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}
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if _, err = io.Copy(wc, body); err != nil {
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return fmt.Errorf("failed to : %w", err)
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}
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if err = wc.Close(); err != nil {
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return fmt.Errorf("failed to close: %w", err)
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}
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if err = client.Quit(); err != nil {
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return fmt.Errorf("failed to quit: %w", err)
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}
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return nil
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}
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