71 lines
1.8 KiB
Go
71 lines
1.8 KiB
Go
package mail
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import (
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"crypto/tls"
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"fmt"
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"net/smtp"
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"doormile/config"
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)
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func SendOTPEmail(cfg *config.Config, toEmail, code string) error {
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subject := "Your Doormile verification code"
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body := fmt.Sprintf(
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"Your Doormile verification code is %s.\r\n\r\nIt expires in 5 minutes. If you didn't request this, you can ignore this email.",
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code,
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)
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msg := []byte(fmt.Sprintf(
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"From: %s\r\nTo: %s\r\nSubject: %s\r\nMIME-Version: 1.0\r\nContent-Type: text/plain; charset=\"utf-8\"\r\n\r\n%s\r\n",
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cfg.SMTPFrom, toEmail, subject, body,
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))
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auth := smtp.PlainAuth("", cfg.SMTPUser, cfg.SMTPPassword, cfg.SMTPHost)
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// Port 465 is implicit TLS (encrypted from the first byte); everything else
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// (587, 25) goes through smtp.SendMail's opportunistic STARTTLS upgrade.
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if cfg.SMTPPort == "465" {
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return sendImplicitTLS(cfg, auth, toEmail, msg)
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}
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addr := fmt.Sprintf("%s:%s", cfg.SMTPHost, cfg.SMTPPort)
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return smtp.SendMail(addr, auth, cfg.SMTPFrom, []string{toEmail}, msg)
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}
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func sendImplicitTLS(cfg *config.Config, auth smtp.Auth, toEmail string, msg []byte) error {
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addr := fmt.Sprintf("%s:%s", cfg.SMTPHost, cfg.SMTPPort)
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conn, err := tls.Dial("tcp", addr, &tls.Config{ServerName: cfg.SMTPHost})
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if err != nil {
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return fmt.Errorf("tls dial failed: %w", err)
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}
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defer conn.Close()
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client, err := smtp.NewClient(conn, cfg.SMTPHost)
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if err != nil {
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return fmt.Errorf("smtp client init failed: %w", err)
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}
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defer client.Close()
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if err := client.Auth(auth); err != nil {
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return fmt.Errorf("smtp auth failed: %w", err)
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}
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if err := client.Mail(cfg.SMTPFrom); err != nil {
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return err
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}
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if err := client.Rcpt(toEmail); err != nil {
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return err
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}
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w, err := client.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 client.Quit()
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}
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