110 lines
2.3 KiB
Go
110 lines
2.3 KiB
Go
package smtp
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import (
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"crypto/tls"
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"io"
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"net/smtp"
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"strings"
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"github.com/rs/zerolog"
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"gitlab.com/etke.cc/go/trysmtp"
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)
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type MailSender interface {
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Send(from string, to string, data string) error
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}
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// SMTP client
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type Client struct {
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config *RelayConfig
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log *zerolog.Logger
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}
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func newClient(cfg *RelayConfig, log *zerolog.Logger) *Client {
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return &Client{
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config: cfg,
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log: log,
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}
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}
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// Send email
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func (c Client) Send(from string, to string, data string) error {
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c.log.Debug().Str("from", from).Str("to", to).Msg("sending email")
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var conn *smtp.Client
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var err error
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if c.config.Host != "" {
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conn, err = c.createDirectClient(from, to)
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} else {
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conn, err = trysmtp.Connect(from, to)
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}
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if conn == nil {
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c.log.Error().Err(err).Str("server_of", to).Msg("cannot connect to SMTP server")
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return err
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}
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if err != nil {
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c.log.Warn().Err(err).Str("server_of", to).Msg("connection to the SMTP server returned non-fatal error(-s)")
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}
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defer conn.Close()
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var w io.WriteCloser
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w, err = conn.Data()
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if err != nil {
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c.log.Error().Err(err).Msg("cannot send DATA command")
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return err
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}
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defer w.Close()
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c.log.Debug().Str("DATA", data).Msg("sending command")
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_, err = strings.NewReader(data).WriteTo(w)
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if err != nil {
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c.log.Error().Err(err).Msg("cannot write DATA")
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return err
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}
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c.log.Debug().Msg("email has been sent")
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return nil
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}
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// createDirectClient connects directly to the provided smtp host
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func (c *Client) createDirectClient(from string, to string) (*smtp.Client, error) {
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localname := strings.SplitN(from, "@", 2)[1]
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target := c.config.Host + ":" + c.config.Port
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conn, err := smtp.Dial(target)
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if err != nil {
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return nil, err
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}
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err = conn.Hello(localname)
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if err != nil {
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return nil, err
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}
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if ok, _ := conn.Extension("STARTTLS"); ok {
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config := &tls.Config{ServerName: c.config.Host}
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conn.StartTLS(config) //nolint:errcheck // if it doesn't work - we can't do anything anyway
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}
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if c.config.Usename != "" {
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err = conn.Auth(smtp.PlainAuth("", c.config.Usename, c.config.Password, c.config.Host))
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if err != nil {
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conn.Close()
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return nil, err
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}
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}
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err = conn.Mail(from)
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if err != nil {
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conn.Close()
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return nil, err
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}
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err = conn.Rcpt(to)
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if err != nil {
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conn.Close()
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return nil, err
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}
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return conn, nil
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}
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