Add basic mailing listspre-refactor

1 files changed, 185 insertions, 0 deletions

diff --git a/forged/internal/unsorted/smtp_relay.go b/forged/internal/unsorted/smtp_relay.go
new file mode 100644
index 0000000..b90c8bd
--- /dev/null
+++ b/forged/internal/unsorted/smtp_relay.go
@@ -0,0 +1,185 @@
+// SPDX-License-Identifier: AGPL-3.0-only
+// SPDX-FileCopyrightText: Copyright (c) 2025 Runxi Yu <https://runxiyu.org>
+
+package unsorted
+
+import (
+	"context"
+	"crypto/tls"
+	"errors"
+	"fmt"
+	"log/slog"
+	"net"
+	stdsmtp "net/smtp"
+	"time"
+
+	"github.com/emersion/go-sasl"
+	"github.com/emersion/go-smtp"
+)
+
+// relayMailingListMessage connects to the configured SMTP relay and sends the
+// raw message to all subscribers of the given list. The message is written verbatim
+// from this point on and there is no modification of any headers or whatever,
+func (s *Server) relayMailingListMessage(ctx context.Context, listID int, envelopeFrom string, raw []byte) error {
+	rows, err := s.database.Query(ctx, `SELECT email FROM mailing_list_subscribers WHERE list_id = $1`, listID)
+	if err != nil {
+		return err
+	}
+	defer rows.Close()
+	var recipients []string
+	for rows.Next() {
+		var email string
+		if err = rows.Scan(&email); err != nil {
+			return err
+		}
+		recipients = append(recipients, email)
+	}
+	if err = rows.Err(); err != nil {
+		return err
+	}
+	if len(recipients) == 0 {
+		slog.Info("mailing list has no subscribers", "list_id", listID)
+		return nil
+	}
+
+	netw := s.config.SMTP.Net
+	if netw == "" {
+		netw = "tcp"
+	}
+	if s.config.SMTP.Addr == "" {
+		return errors.New("smtp relay addr not configured")
+	}
+	helloName := s.config.SMTP.HelloName
+	if helloName == "" {
+		helloName = s.config.LMTP.Domain
+	}
+	transport := s.config.SMTP.Transport
+	if transport == "" {
+		transport = "plain"
+	}
+
+	switch transport {
+	case "plain", "tls":
+		d := net.Dialer{Timeout: 30 * time.Second}
+		var conn net.Conn
+		var err error
+		if transport == "tls" {
+			tlsCfg := &tls.Config{ServerName: hostFromAddr(s.config.SMTP.Addr), InsecureSkipVerify: s.config.SMTP.TLSInsecure}
+			conn, err = tls.DialWithDialer(&d, netw, s.config.SMTP.Addr, tlsCfg)
+		} else {
+			conn, err = d.DialContext(ctx, netw, s.config.SMTP.Addr)
+		}
+		if err != nil {
+			return fmt.Errorf("dial smtp: %w", err)
+		}
+		defer conn.Close()
+
+		c := smtp.NewClient(conn)
+		defer c.Close()
+
+		if err := c.Hello(helloName); err != nil {
+			return fmt.Errorf("smtp hello: %w", err)
+		}
+
+		if s.config.SMTP.Username != "" {
+			mech := sasl.NewPlainClient("", s.config.SMTP.Username, s.config.SMTP.Password)
+			if err := c.Auth(mech); err != nil {
+				return fmt.Errorf("smtp auth: %w", err)
+			}
+		}
+
+		if err := c.Mail(envelopeFrom, &smtp.MailOptions{}); err != nil {
+			return fmt.Errorf("smtp mail from: %w", err)
+		}
+		for _, rcpt := range recipients {
+			if err := c.Rcpt(rcpt, &smtp.RcptOptions{}); err != nil {
+				return fmt.Errorf("smtp rcpt %s: %w", rcpt, err)
+			}
+		}
+		wc, err := c.Data()
+		if err != nil {
+			return fmt.Errorf("smtp data: %w", err)
+		}
+		if _, err := wc.Write(raw); err != nil {
+			_ = wc.Close()
+			return fmt.Errorf("smtp write: %w", err)
+		}
+		if err := wc.Close(); err != nil {
+			return fmt.Errorf("smtp data close: %w", err)
+		}
+		if err := c.Quit(); err != nil {
+			return fmt.Errorf("smtp quit: %w", err)
+		}
+		return nil
+	case "starttls":
+		d := net.Dialer{Timeout: 30 * time.Second}
+		conn, err := d.DialContext(ctx, netw, s.config.SMTP.Addr)
+		if err != nil {
+			return fmt.Errorf("dial smtp: %w", err)
+		}
+		defer conn.Close()
+
+		host := hostFromAddr(s.config.SMTP.Addr)
+		c, err := stdsmtp.NewClient(conn, host)
+		if err != nil {
+			return fmt.Errorf("smtp new client: %w", err)
+		}
+		defer c.Close()
+
+		if err := c.Hello(helloName); err != nil {
+			return fmt.Errorf("smtp hello: %w", err)
+		}
+		if ok, _ := c.Extension("STARTTLS"); !ok {
+			return errors.New("smtp server does not support STARTTLS")
+		}
+		tlsCfg := &tls.Config{ServerName: host, InsecureSkipVerify: s.config.SMTP.TLSInsecure} // #nosec G402
+		if err := c.StartTLS(tlsCfg); err != nil {
+			return fmt.Errorf("starttls: %w", err)
+		}
+
+		// seems like ehlo is required after starttls
+		if err := c.Hello(helloName); err != nil {
+			return fmt.Errorf("smtp hello (post-starttls): %w", err)
+		}
+
+		if s.config.SMTP.Username != "" {
+			auth := stdsmtp.PlainAuth("", s.config.SMTP.Username, s.config.SMTP.Password, host)
+			if err := c.Auth(auth); err != nil {
+				return fmt.Errorf("smtp auth: %w", err)
+			}
+		}
+		if err := c.Mail(envelopeFrom); err != nil {
+			return fmt.Errorf("smtp mail from: %w", err)
+		}
+		for _, rcpt := range recipients {
+			if err := c.Rcpt(rcpt); err != nil {
+				return fmt.Errorf("smtp rcpt %s: %w", rcpt, err)
+			}
+		}
+		wc, err := c.Data()
+		if err != nil {
+			return fmt.Errorf("smtp data: %w", err)
+		}
+		if _, err := wc.Write(raw); err != nil {
+			_ = wc.Close()
+			return fmt.Errorf("smtp write: %w", err)
+		}
+		if err := wc.Close(); err != nil {
+			return fmt.Errorf("smtp data close: %w", err)
+		}
+		if err := c.Quit(); err != nil {
+			return fmt.Errorf("smtp quit: %w", err)
+		}
+		return nil
+	default:
+		return fmt.Errorf("unknown smtp transport: %q", transport)
+	}
+}
+
+func hostFromAddr(addr string) string {
+	host, _, err := net.SplitHostPort(addr)
+	if err != nil || host == "" {
+		return addr
+	}
+	return host
+}