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143 lines
3.1 KiB
143 lines
3.1 KiB
package mailinglist
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import (
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"context"
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"errors"
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"strings"
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"github.com/emersion/go-sasl"
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"github.com/emersion/go-smtp"
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"github.com/mediocregopher/blog.mediocregopher.com/srv/cfg"
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"github.com/mediocregopher/mediocre-go-lib/v2/mctx"
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"github.com/mediocregopher/mediocre-go-lib/v2/mlog"
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)
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// Mailer is used to deliver emails to arbitrary recipients.
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type Mailer interface {
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Send(to, subject, body string) error
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}
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type logMailer struct {
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logger *mlog.Logger
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}
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// NewLogMailer returns a Mailer instance which will not actually send any
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// emails, it will only log to the given Logger when Send is called.
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func NewLogMailer(logger *mlog.Logger) Mailer {
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return &logMailer{logger: logger}
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}
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func (l *logMailer) Send(to, subject, body string) error {
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ctx := mctx.Annotate(context.Background(),
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"to", to,
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"subject", subject,
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)
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l.logger.Info(ctx, "would have sent email")
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return nil
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}
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// NullMailer acts as a Mailer but actually just does nothing.
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var NullMailer = nullMailer{}
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type nullMailer struct{}
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func (nullMailer) Send(to, subject, body string) error {
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return nil
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}
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// MailerParams are used to initialize a new Mailer instance.
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type MailerParams struct {
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SMTPAddr string
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// Optional, if not given then no auth is attempted.
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SMTPAuth sasl.Client
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// The sending email address to use for all emails being sent.
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SendAs string
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}
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// SetupCfg implement the cfg.Cfger interface.
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func (m *MailerParams) SetupCfg(cfg *cfg.Cfg) {
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cfg.StringVar(&m.SMTPAddr, "ml-smtp-addr", "", "Address of SMTP server to use for sending emails for the mailing list")
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smtpAuthStr := cfg.String("ml-smtp-auth", "", "user:pass to use when authenticating with the mailing list SMTP server. The given user will also be used as the From address.")
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cfg.OnInit(func(ctx context.Context) error {
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if m.SMTPAddr == "" {
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return nil
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}
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smtpAuthParts := strings.SplitN(*smtpAuthStr, ":", 2)
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if len(smtpAuthParts) < 2 {
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return errors.New("invalid -ml-smtp-auth")
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}
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m.SMTPAuth = sasl.NewPlainClient("", smtpAuthParts[0], smtpAuthParts[1])
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m.SendAs = smtpAuthParts[0]
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return nil
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})
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}
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// Annotate implements mctx.Annotator interface.
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func (m *MailerParams) Annotate(a mctx.Annotations) {
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if m.SMTPAddr == "" {
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return
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}
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a["smtpAddr"] = m.SMTPAddr
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a["smtpSendAs"] = m.SendAs
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}
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type mailer struct {
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params MailerParams
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}
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// NewMailer initializes and returns a Mailer which will use an external SMTP
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// server to deliver email.
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func NewMailer(params MailerParams) Mailer {
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return &mailer{
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params: params,
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}
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}
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func (m *mailer) Send(to, subject, body string) error {
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msg := []byte("From: " + m.params.SendAs + "\r\n" +
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"To: " + to + "\r\n" +
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"Subject: " + subject + "\r\n\r\n" +
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body + "\r\n")
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c, err := smtp.Dial(m.params.SMTPAddr)
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if err != nil {
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return err
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}
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defer c.Close()
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if err = c.Auth(m.params.SMTPAuth); err != nil {
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return err
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}
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if err = c.Mail(m.params.SendAs, nil); err != nil {
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return err
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}
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if err = c.Rcpt(to); err != nil {
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return err
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}
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w, err := c.Data()
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if err != nil {
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return err
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}
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if _, err = w.Write(msg); err != nil {
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return err
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}
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if err = w.Close(); err != nil {
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return err
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}
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return c.Quit()
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}
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