mox/smtpserver/dsn.go
Mechiel Lukkien 9e7d6b85b7
queue: deliver to multiple recipients in a single smtp transaction
transferring the data only once. we only do this when the recipient domains
are the same. when queuing, we now take care to set the same NextAttempt
timestamp, so queued messages are actually eligable for combined delivery.

this adds a DeliverMultiple to the smtp client. for pipelined requests, it will
send all RCPT TO (and MAIL and DATA) in one go, and handles the various
responses and error conditions, returning either an overal error, or per
recipient smtp responses. the results of the smtp LIMITS extension are also
available in the smtp client now.

this also takes the "LIMITS RCPTMAX" smtp extension into account: if the server
only accepts a single recipient, we won't send multiple.
if a server doesn't announce a RCPTMAX limit, but still has one (like mox does
for non-spf-verified transactions), we'll recognize code 452 and 552 (for
historic reasons) as temporary error, and try again in a separate transaction
immediately after. we don't yet implement "LIMITS MAILMAX", doesn't seem likely
in practice.
2024-03-07 10:07:53 +01:00

63 lines
1.8 KiB
Go

package smtpserver
import (
"context"
"fmt"
"time"
"github.com/mjl-/mox/dsn"
"github.com/mjl-/mox/mlog"
"github.com/mjl-/mox/mox-"
"github.com/mjl-/mox/queue"
"github.com/mjl-/mox/smtp"
"github.com/mjl-/mox/store"
)
// compose dsn message and add it to the queue for delivery to rcptTo.
func queueDSN(ctx context.Context, log mlog.Log, c *conn, rcptTo smtp.Path, m dsn.Message, requireTLS bool) error {
buf, err := m.Compose(c.log, false)
if err != nil {
return err
}
bufDKIM, err := mox.DKIMSign(ctx, c.log, m.From, false, buf)
log.Check(err, "dkim signing dsn")
buf = append([]byte(bufDKIM), buf...)
var bufUTF8 []byte
if c.smtputf8 {
bufUTF8, err = m.Compose(c.log, true)
if err != nil {
c.log.Errorx("composing dsn with utf-8 for incoming delivery for unknown user, continuing with ascii-only dsn", err)
} else {
bufUTF8DKIM, err := mox.DKIMSign(ctx, log, m.From, true, bufUTF8)
log.Check(err, "dkim signing dsn with utf8")
bufUTF8 = append([]byte(bufUTF8DKIM), bufUTF8...)
}
}
f, err := store.CreateMessageTemp(c.log, "smtp-dsn")
if err != nil {
return fmt.Errorf("creating temp file: %w", err)
}
defer store.CloseRemoveTempFile(c.log, f, "smtpserver dsn message")
if _, err := f.Write([]byte(buf)); err != nil {
return fmt.Errorf("writing dsn file: %w", err)
}
// Queue DSN with null reverse path so failures to deliver will eventually drop the
// message instead of causing delivery loops.
// ../rfc/3464:433
const has8bit = false
const smtputf8 = false
var reqTLS *bool
if requireTLS {
reqTLS = &requireTLS
}
qm := queue.MakeMsg(smtp.Path{}, rcptTo, has8bit, smtputf8, int64(len(buf)), m.MessageID, nil, reqTLS, time.Now())
qm.DSNUTF8 = bufUTF8
if err := queue.Add(ctx, c.log, "", f, qm); err != nil {
return err
}
return nil
}