feat: hub console backend — complete API surface

internal/mail/mail.go

@@ -0,0 +1,70 @@
+package mail
+
+import (
+	"crypto/tls"
+	"fmt"
+	"net/smtp"
+
+	"doormile/config"
+)
+
+func SendOTPEmail(cfg *config.Config, toEmail, code string) error {
+	subject := "Your Doormile verification code"
+	body := fmt.Sprintf(
+		"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.",
+		code,
+	)
+
+	msg := []byte(fmt.Sprintf(
+		"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",
+		cfg.SMTPFrom, toEmail, subject, body,
+	))
+
+	auth := smtp.PlainAuth("", cfg.SMTPUser, cfg.SMTPPassword, cfg.SMTPHost)
+
+	// Port 465 is implicit TLS (encrypted from the first byte); everything else
+	// (587, 25) goes through smtp.SendMail's opportunistic STARTTLS upgrade.
+	if cfg.SMTPPort == "465" {
+		return sendImplicitTLS(cfg, auth, toEmail, msg)
+	}
+
+	addr := fmt.Sprintf("%s:%s", cfg.SMTPHost, cfg.SMTPPort)
+	return smtp.SendMail(addr, auth, cfg.SMTPFrom, []string{toEmail}, msg)
+}
+
+func sendImplicitTLS(cfg *config.Config, auth smtp.Auth, toEmail string, msg []byte) error {
+	addr := fmt.Sprintf("%s:%s", cfg.SMTPHost, cfg.SMTPPort)
+
+	conn, err := tls.Dial("tcp", addr, &tls.Config{ServerName: cfg.SMTPHost})
+	if err != nil {
+		return fmt.Errorf("tls dial failed: %w", err)
+	}
+	defer conn.Close()
+
+	client, err := smtp.NewClient(conn, cfg.SMTPHost)
+	if err != nil {
+		return fmt.Errorf("smtp client init failed: %w", err)
+	}
+	defer client.Close()
+
+	if err := client.Auth(auth); err != nil {
+		return fmt.Errorf("smtp auth failed: %w", err)
+	}
+	if err := client.Mail(cfg.SMTPFrom); err != nil {
+		return err
+	}
+	if err := client.Rcpt(toEmail); err != nil {
+		return err
+	}
+	w, err := client.Data()
+	if err != nil {
+		return err
+	}
+	if _, err := w.Write(msg); err != nil {
+		return err
+	}
+	if err := w.Close(); err != nil {
+		return err
+	}
+	return client.Quit()
+}