mirror of
https://github.com/mjl-/mox.git
synced 2025-07-12 17:44:35 +03:00
include full smtp response in dsn on errors
we now keep track of the full smtp error responses, potentially multi-line. and we include it in a dsn in the first free-form human-readable text. it can have multiple lines in practice, e.g. when a destination mail server tries to be helpful in explaining what the problem is.
This commit is contained in:
Mechiel Lukkien
@ -89,14 +89,14 @@ var (
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)
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// todo: rename function, perhaps put some of the params in a delivery struct so we don't pass all the params all the time?
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func fail(ctx context.Context, qlog mlog.Log, m Msg, backoff time.Duration, permanent bool, remoteMTA dsn.NameIP, secodeOpt, errmsg string) {
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func fail(ctx context.Context, qlog mlog.Log, m Msg, backoff time.Duration, permanent bool, remoteMTA dsn.NameIP, secodeOpt, errmsg string, moreLines []string) {
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// todo future: when we implement relaying, we should be able to send DSNs to non-local users. and possibly specify a null mailfrom. ../rfc/5321:1503
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// todo future: when we implement relaying, and a dsn cannot be delivered, and requiretls was active, we cannot drop the message. instead deliver to local postmaster? though ../rfc/8689:383 may intend to say the dsn should be delivered without requiretls?
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// todo future: when we implement smtp dsn extension, parameter RET=FULL must be disregarded for messages with REQUIRETLS. ../rfc/8689:379
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if permanent || m.MaxAttempts == 0 && m.Attempts >= 8 || m.MaxAttempts > 0 && m.Attempts >= m.MaxAttempts {
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qlog.Errorx("permanent failure delivering from queue", errors.New(errmsg))
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deliverDSNFailure(ctx, qlog, m, remoteMTA, secodeOpt, errmsg)
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deliverDSNFailure(ctx, qlog, m, remoteMTA, secodeOpt, errmsg, moreLines)
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if err := queueDelete(context.Background(), m.ID); err != nil {
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qlog.Errorx("deleting message from queue after permanent failure", err)
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@ -116,7 +116,7 @@ func fail(ctx context.Context, qlog mlog.Log, m Msg, backoff time.Duration, perm
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qlog.Errorx("temporary failure delivering from queue, sending delayed dsn", errors.New(errmsg), slog.Duration("backoff", backoff))
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retryUntil := m.LastAttempt.Add((4 + 8 + 16) * time.Hour)
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deliverDSNDelay(ctx, qlog, m, remoteMTA, secodeOpt, errmsg, retryUntil)
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deliverDSNDelay(ctx, qlog, m, remoteMTA, secodeOpt, errmsg, moreLines, retryUntil)
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} else {
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qlog.Errorx("temporary failure delivering from queue", errors.New(errmsg), slog.Duration("backoff", backoff), slog.Time("nextattempt", m.NextAttempt))
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}
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@ -168,7 +168,7 @@ func deliverDirect(qlog mlog.Log, resolver dns.Resolver, dialer smtpclient.Diale
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recipientDomainResult.Summary.TotalFailureSessionCount++
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}
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fail(ctx, qlog, m, backoff, permanent, dsn.NameIP{}, "", err.Error())
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fail(ctx, qlog, m, backoff, permanent, dsn.NameIP{}, "", err.Error(), nil)
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return
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}
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@ -188,7 +188,7 @@ func deliverDirect(qlog mlog.Log, resolver dns.Resolver, dialer smtpclient.Diale
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} else {
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qlog.Infox("mtasts lookup temporary error, aborting delivery attempt", err, slog.Any("domain", origNextHop))
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recipientDomainResult.Summary.TotalFailureSessionCount++
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fail(ctx, qlog, m, backoff, false, dsn.NameIP{}, "", err.Error())
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fail(ctx, qlog, m, backoff, false, dsn.NameIP{}, "", err.Error(), nil)
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return
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}
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}
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@ -206,6 +206,7 @@ func deliverDirect(qlog mlog.Log, resolver dns.Resolver, dialer smtpclient.Diale
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// ../rfc/3974:268.
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var remoteMTA dsn.NameIP
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var secodeOpt, errmsg string
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var moreLines []string // For additional SMTP response lines, included in DSN.
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permanent = false
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nmissingRequireTLS := 0
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// todo: should make distinction between host permanently not accepting the message, and the message not being deliverable permanently. e.g. a mx host may have a size limit, or not accept 8bitmime, while another host in the list does accept the message. same for smtputf8, ../rfc/6531:555
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@ -230,6 +231,7 @@ func deliverDirect(qlog mlog.Log, resolver dns.Resolver, dialer smtpclient.Diale
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metricTLSRequiredNoIgnored.WithLabelValues("mtastsmx").Inc()
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} else {
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errmsg = fmt.Sprintf("mx host %s does not match enforced mta-sts policy with hosts %s", h.Domain, strings.Join(policyHosts, ","))
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moreLines = nil
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qlog.Error("mx host does not match mta-sts policy in mode enforce, skipping", slog.Any("host", h.Domain), slog.Any("policyhosts", policyHosts))
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recipientDomainResult.Summary.TotalFailureSessionCount++
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continue
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@ -269,7 +271,7 @@ func deliverDirect(qlog mlog.Log, resolver dns.Resolver, dialer smtpclient.Diale
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var badTLS, ok bool
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var hostResult tlsrpt.Result
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permanent, tlsDANE, badTLS, secodeOpt, remoteIP, errmsg, hostResult, ok = deliverHost(nqlog, resolver, dialer, ourHostname, transportName, h, enforceMTASTS, haveMX, origNextHopAuthentic, origNextHop, expandedNextHopAuthentic, expandedNextHop, &m, tlsMode, tlsPKIX, &recipientDomainResult)
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permanent, tlsDANE, badTLS, secodeOpt, remoteIP, errmsg, moreLines, hostResult, ok = deliverHost(nqlog, resolver, dialer, ourHostname, transportName, h, enforceMTASTS, haveMX, origNextHopAuthentic, origNextHop, expandedNextHopAuthentic, expandedNextHop, &m, tlsMode, tlsPKIX, &recipientDomainResult)
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var zerotype tlsrpt.PolicyType
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if hostResult.Policy.Type != zerotype {
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@ -296,7 +298,7 @@ func deliverDirect(qlog mlog.Log, resolver dns.Resolver, dialer smtpclient.Diale
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slog.Bool("enforcemtasts", enforceMTASTS),
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slog.Bool("tlsdane", tlsDANE),
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slog.Any("requiretls", m.RequireTLS))
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permanent, _, _, secodeOpt, remoteIP, errmsg, _, ok = deliverHost(nqlog, resolver, dialer, ourHostname, transportName, h, enforceMTASTS, haveMX, origNextHopAuthentic, origNextHop, expandedNextHopAuthentic, expandedNextHop, &m, smtpclient.TLSSkip, false, &tlsrpt.Result{})
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permanent, _, _, secodeOpt, remoteIP, errmsg, moreLines, _, ok = deliverHost(nqlog, resolver, dialer, ourHostname, transportName, h, enforceMTASTS, haveMX, origNextHopAuthentic, origNextHop, expandedNextHopAuthentic, expandedNextHop, &m, smtpclient.TLSSkip, false, &tlsrpt.Result{})
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}
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if ok {
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@ -332,7 +334,7 @@ func deliverDirect(qlog mlog.Log, resolver dns.Resolver, dialer smtpclient.Diale
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permanent = true
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}
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fail(ctx, qlog, m, backoff, permanent, remoteMTA, secodeOpt, errmsg)
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fail(ctx, qlog, m, backoff, permanent, remoteMTA, secodeOpt, errmsg, moreLines)
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return
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}
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@ -352,7 +354,7 @@ func deliverDirect(qlog mlog.Log, resolver dns.Resolver, dialer smtpclient.Diale
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// The returned hostResult holds TLSRPT reporting results for the connection
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// attempt. Its policy type can be the zero value, indicating there was no finding
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// (e.g. internal error).
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func deliverHost(log mlog.Log, resolver dns.Resolver, dialer smtpclient.Dialer, ourHostname dns.Domain, transportName string, host dns.IPDomain, enforceMTASTS, haveMX, origNextHopAuthentic bool, origNextHop dns.Domain, expandedNextHopAuthentic bool, expandedNextHop dns.Domain, m *Msg, tlsMode smtpclient.TLSMode, tlsPKIX bool, recipientDomainResult *tlsrpt.Result) (permanent, tlsDANE, badTLS bool, secodeOpt string, remoteIP net.IP, errmsg string, hostResult tlsrpt.Result, ok bool) {
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func deliverHost(log mlog.Log, resolver dns.Resolver, dialer smtpclient.Dialer, ourHostname dns.Domain, transportName string, host dns.IPDomain, enforceMTASTS, haveMX, origNextHopAuthentic bool, origNextHop dns.Domain, expandedNextHopAuthentic bool, expandedNextHop dns.Domain, m *Msg, tlsMode smtpclient.TLSMode, tlsPKIX bool, recipientDomainResult *tlsrpt.Result) (permanent, tlsDANE, badTLS bool, secodeOpt string, remoteIP net.IP, errmsg string, moreLines []string, hostResult tlsrpt.Result, ok bool) {
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// About attempting delivery to multiple addresses of a host: ../rfc/5321:3898
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tlsRequiredNo := m.RequireTLS != nil && !*m.RequireTLS
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@ -386,7 +388,7 @@ func deliverHost(log mlog.Log, resolver dns.Resolver, dialer smtpclient.Dialer,
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// Open message to deliver.
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f, err := os.Open(m.MessagePath())
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if err != nil {
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return false, false, false, "", nil, fmt.Sprintf("open message file: %s", err), hostResult, false
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return false, false, false, "", nil, fmt.Sprintf("open message file: %s", err), nil, hostResult, false
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}
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msgr := store.FileMsgReader(m.MsgPrefix, f)
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defer func() {
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@ -517,7 +519,7 @@ func deliverHost(log mlog.Log, resolver dns.Resolver, dialer smtpclient.Dialer,
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log.Info("verified tls is required, but destination has no usable dane records and no mta-sts policy, canceling delivery attempt to host")
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metricRequireTLSUnsupported.WithLabelValues("nopolicy").Inc()
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// Resond with proper enhanced status code. ../rfc/8689:301
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return false, tlsDANE, false, smtp.SePol7MissingReqTLS, remoteIP, "missing required tls verification mechanism", hostResult, false
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return false, tlsDANE, false, smtp.SePol7MissingReqTLS, remoteIP, "missing required tls verification mechanism", nil, hostResult, false
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}
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// Dial the remote host given the IPs if no error yet.
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@ -545,7 +547,7 @@ func deliverHost(log mlog.Log, resolver dns.Resolver, dialer smtpclient.Dialer,
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metricConnection.WithLabelValues(result).Inc()
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if err != nil {
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log.Debugx("connecting to remote smtp", err, slog.Any("host", host))
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return false, tlsDANE, false, "", remoteIP, fmt.Sprintf("dialing smtp server: %v", err), hostResult, false
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return false, tlsDANE, false, "", remoteIP, fmt.Sprintf("dialing smtp server: %v", err), nil, hostResult, false
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}
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var mailFrom string
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@ -636,7 +638,7 @@ func deliverHost(log mlog.Log, resolver dns.Resolver, dialer smtpclient.Dialer,
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deliveryResult = "error"
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}
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if err == nil {
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return false, tlsDANE, false, "", remoteIP, "", hostResult, true
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return false, tlsDANE, false, "", remoteIP, "", nil, hostResult, true
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} else if cerr, ok := err.(smtpclient.Error); ok {
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// If we are being rejected due to policy reasons on the first
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// attempt and remote has both IPv4 and IPv6, we'll give it
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@ -652,9 +654,9 @@ func deliverHost(log mlog.Log, resolver dns.Resolver, dialer smtpclient.Dialer,
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secode = smtp.SePol7MissingReqTLS
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metricRequireTLSUnsupported.WithLabelValues("norequiretls").Inc()
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}
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return permanent, tlsDANE, errors.Is(cerr, smtpclient.ErrTLS), secode, remoteIP, cerr.Error(), hostResult, false
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return permanent, tlsDANE, errors.Is(cerr, smtpclient.ErrTLS), secode, remoteIP, cerr.Error(), cerr.MoreLines, hostResult, false
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} else {
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return false, tlsDANE, errors.Is(cerr, smtpclient.ErrTLS), "", remoteIP, err.Error(), hostResult, false
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return false, tlsDANE, errors.Is(cerr, smtpclient.ErrTLS), "", remoteIP, err.Error(), nil, hostResult, false
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}
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}
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@ -6,6 +6,7 @@ import (
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"fmt"
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"log/slog"
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"os"
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"strings"
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"time"
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"github.com/prometheus/client_golang/prometheus"
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@ -29,7 +30,7 @@ var (
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)
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)
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func deliverDSNFailure(ctx context.Context, log mlog.Log, m Msg, remoteMTA dsn.NameIP, secodeOpt, errmsg string) {
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func deliverDSNFailure(ctx context.Context, log mlog.Log, m Msg, remoteMTA dsn.NameIP, secodeOpt, errmsg string, moreLines []string) {
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const subject = "mail delivery failed"
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message := fmt.Sprintf(`
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Delivery has failed permanently for your email to:
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@ -41,12 +42,12 @@ No further deliveries will be attempted.
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Error during the last delivery attempt:
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%s
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`, m.Recipient().XString(m.SMTPUTF8), errmsg)
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`, m.Recipient().XString(m.SMTPUTF8), strings.Join(append([]string{errmsg}, moreLines...), "\n\t"))
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deliverDSN(ctx, log, m, remoteMTA, secodeOpt, errmsg, true, nil, subject, message)
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}
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func deliverDSNDelay(ctx context.Context, log mlog.Log, m Msg, remoteMTA dsn.NameIP, secodeOpt, errmsg string, retryUntil time.Time) {
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func deliverDSNDelay(ctx context.Context, log mlog.Log, m Msg, remoteMTA dsn.NameIP, secodeOpt, errmsg string, moreLines []string, retryUntil time.Time) {
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// Should not happen, but doesn't hurt to prevent sending delayed delivery
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// notifications for DMARC reports. We don't want to waste postmaster attention.
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if m.IsDMARCReport {
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@ -65,7 +66,7 @@ If these attempts all fail, you will receive a notice.
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Error during the last delivery attempt:
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%s
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`, m.Recipient().XString(false), errmsg)
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`, m.Recipient().XString(false), strings.Join(append([]string{errmsg}, moreLines...), "\n\t"))
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deliverDSN(ctx, log, m, remoteMTA, secodeOpt, errmsg, false, &retryUntil, subject, message)
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}
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@ -581,7 +581,7 @@ func deliver(log mlog.Log, resolver dns.Resolver, m Msg) {
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transport, ok = mox.Conf.Static.Transports[m.Transport]
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if !ok {
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var remoteMTA dsn.NameIP // Zero value, will not be included in DSN. ../rfc/3464:1027
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fail(ctx, qlog, m, backoff, false, remoteMTA, "", fmt.Sprintf("cannot find transport %q", m.Transport))
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fail(ctx, qlog, m, backoff, false, remoteMTA, "", fmt.Sprintf("cannot find transport %q", m.Transport), nil)
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return
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}
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transportName = m.Transport
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@ -692,10 +692,10 @@ func deliver(log mlog.Log, resolver dns.Resolver, m Msg) {
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if transport.Socks != nil {
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socksdialer, err := proxy.SOCKS5("tcp", transport.Socks.Address, nil, &net.Dialer{})
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if err != nil {
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fail(ctx, qlog, m, backoff, false, dsn.NameIP{}, "", fmt.Sprintf("socks dialer: %v", err))
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fail(ctx, qlog, m, backoff, false, dsn.NameIP{}, "", fmt.Sprintf("socks dialer: %v", err), nil)
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return
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} else if d, ok := socksdialer.(smtpclient.Dialer); !ok {
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fail(ctx, qlog, m, backoff, false, dsn.NameIP{}, "", "socks dialer is not a contextdialer")
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fail(ctx, qlog, m, backoff, false, dsn.NameIP{}, "", "socks dialer is not a contextdialer", nil)
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return
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} else {
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dialer = d
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@ -78,7 +78,7 @@ func deliverSubmit(qlog mlog.Log, resolver dns.Resolver, dialer smtpclient.Diale
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requireTLS := m.RequireTLS != nil && *m.RequireTLS
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if requireTLS && (tlsMode != smtpclient.TLSRequiredStartTLS && tlsMode != smtpclient.TLSImmediate || !tlsPKIX) {
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errmsg = fmt.Sprintf("transport %s: message requires verified tls but transport does not verify tls", transportName)
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fail(ctx, qlog, m, backoff, true, dsn.NameIP{}, smtp.SePol7MissingReqTLS, errmsg)
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fail(ctx, qlog, m, backoff, true, dsn.NameIP{}, smtp.SePol7MissingReqTLS, errmsg, nil)
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return
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}
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@ -115,7 +115,7 @@ func deliverSubmit(qlog mlog.Log, resolver dns.Resolver, dialer smtpclient.Diale
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}
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qlog.Errorx("dialing for submission", err, slog.String("remote", addr))
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errmsg = fmt.Sprintf("transport %s: dialing %s for submission: %v", transportName, addr, err)
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fail(ctx, qlog, m, backoff, false, dsn.NameIP{}, "", errmsg)
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fail(ctx, qlog, m, backoff, false, dsn.NameIP{}, "", errmsg, nil)
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return
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}
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dialcancel()
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@ -171,7 +171,7 @@ func deliverSubmit(qlog mlog.Log, resolver dns.Resolver, dialer smtpclient.Diale
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qlog.Errorx("establishing smtp session for submission", err, slog.String("remote", addr))
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errmsg = fmt.Sprintf("transport %s: establishing smtp session with %s for submission: %v", transportName, addr, err)
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secodeOpt = smtperr.Secode
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fail(ctx, qlog, m, backoff, false, remoteMTA, secodeOpt, errmsg)
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fail(ctx, qlog, m, backoff, false, remoteMTA, secodeOpt, errmsg, smtperr.MoreLines)
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return
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}
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defer func() {
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@ -196,7 +196,7 @@ func deliverSubmit(qlog mlog.Log, resolver dns.Resolver, dialer smtpclient.Diale
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if err != nil {
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qlog.Errorx("opening message for delivery", err, slog.String("remote", addr), slog.String("path", p))
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errmsg = fmt.Sprintf("transport %s: opening message file for submission: %v", transportName, err)
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fail(ctx, qlog, m, backoff, false, dsn.NameIP{}, "", errmsg)
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fail(ctx, qlog, m, backoff, false, dsn.NameIP{}, "", errmsg, nil)
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return
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}
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msgr = store.FileMsgReader(m.MsgPrefix, f)
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@ -239,7 +239,7 @@ func deliverSubmit(qlog mlog.Log, resolver dns.Resolver, dialer smtpclient.Diale
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permanent = smtperr.Permanent
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secodeOpt = smtperr.Secode
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errmsg = fmt.Sprintf("transport %s: submitting email to %s: %v", transportName, addr, err)
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fail(ctx, qlog, m, backoff, permanent, remoteMTA, secodeOpt, errmsg)
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fail(ctx, qlog, m, backoff, permanent, remoteMTA, secodeOpt, errmsg, smtperr.MoreLines)
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return
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}
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qlog.Info("delivered from queue with transport")
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Block a user