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smtpserver: when logging recipients, actually show something about the recipient

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before this change, we were logging an empty string, which turned into "[]",
looking like an empty array. misleading and unhelpful.

this is fixed by making struct fields on type recipient "exported" so they can
get logged, and by changing the logging code to log nested
struct/pointer/interface fields if we would otherwise wouldn't log anything
(when only logging more basic data types).

we'll now get log lines like:

	l=info m="deliver attempt to unknown user(s)" pkg=smtpserver recipients="[addr=bogus@test.example]"

for issue #232 by snabb, thanks for reporting!
This commit is contained in:
Mechiel Lukkien 2024-11-01 10:38:31 +01:00
parent 879477a01f
commit 598c5ea6ac
No known key found for this signature in database
2 changed files with 66 additions and 56 deletions
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16
mlog/log.go
View file

@ -426,14 +426,19 @@ func stringValue(iscid, nested bool, v any) string {
} }
n := rv.NumField() n := rv.NumField()
t := rv.Type() t := rv.Type()
b := &strings.Builder{}
// We first try making a string without recursing into structs/pointers/interfaces,
// but will try again with those fields if we otherwise would otherwise log an
// empty string.
for j := 0; j < 2; j++ {
first := true first := true
b := &strings.Builder{}
for i := 0; i < n; i++ { for i := 0; i < n; i++ {
fv := rv.Field(i) fv := rv.Field(i)
if !t.Field(i).IsExported() { if !t.Field(i).IsExported() {
continue continue
} }
if fv.Kind() == reflect.Struct || fv.Kind() == reflect.Ptr || fv.Kind() == reflect.Interface { if j == 0 && (fv.Kind() == reflect.Struct || fv.Kind() == reflect.Ptr || fv.Kind() == reflect.Interface) {
// Don't recurse. // Don't recurse.
continue continue
} }
@ -448,7 +453,12 @@ func stringValue(iscid, nested bool, v any) string {
k := strings.ToLower(t.Field(i).Name) k := strings.ToLower(t.Field(i).Name)
b.WriteString(k + "=" + vs) b.WriteString(k + "=" + vs)
} }
return b.String() rs := b.String()
if rs != "" {
return rs
}
}
return ""
} }
func writeAttr(w io.Writer, separator, group string, a slog.Attr) { func writeAttr(w io.Writer, separator, group string, a slog.Attr) {

72
smtpserver/server.go
View file

@ -344,24 +344,24 @@ type conn struct {
} }
type rcptAccount struct { type rcptAccount struct {
accountName string AccountName string
destination config.Destination Destination config.Destination
canonicalAddress string // Optional catchall part stripped and/or lowercased. CanonicalAddress string // Optional catchall part stripped and/or lowercased.
} }
type rcptAlias struct { type rcptAlias struct {
alias config.Alias Alias config.Alias
canonicalAddress string // Optional catchall part stripped and/or lowercased. CanonicalAddress string // Optional catchall part stripped and/or lowercased.
} }
type recipient struct { type recipient struct {
addr smtp.Path Addr smtp.Path
// If account and alias are both not set, this is not for a local address. This is // If account and alias are both not set, this is not for a local address. This is
// normal for submission, where messages are added to the queue. For incoming // normal for submission, where messages are added to the queue. For incoming
// deliveries, this will result in an error. // deliveries, this will result in an error.
account *rcptAccount // If set, recipient address is for this local account. Account *rcptAccount // If set, recipient address is for this local account.
alias *rcptAlias // If set, for a local alias. Alias *rcptAlias // If set, for a local alias.
} }
func isClosed(err error) bool { func isClosed(err error) bool {
@ -1732,7 +1732,7 @@ func (c *conn) isSMTPUTF8Required(part *message.Part) bool {
} }
// Check all "RCPT TO". // Check all "RCPT TO".
for _, rcpt := range c.recipients { for _, rcpt := range c.recipients {
if hasNonASCII(strings.NewReader(string(rcpt.addr.Localpart))) { if hasNonASCII(strings.NewReader(string(rcpt.Addr.Localpart))) {
return true return true
} }
} }
@ -2037,7 +2037,7 @@ func (c *conn) submit(ctx context.Context, recvHdrFor func(string) string, msgWr
err = c.account.DB.Read(ctx, func(tx *bstore.Tx) error { err = c.account.DB.Read(ctx, func(tx *bstore.Tx) error {
rcpts := make([]smtp.Path, len(c.recipients)) rcpts := make([]smtp.Path, len(c.recipients))
for i, r := range c.recipients { for i, r := range c.recipients {
rcpts[i] = r.addr rcpts[i] = r.Addr
} }
msglimit, rcptlimit, err := c.account.SendLimitReached(tx, rcpts) msglimit, rcptlimit, err := c.account.SendLimitReached(tx, rcpts)
xcheckf(err, "checking sender limit") xcheckf(err, "checking sender limit")
@ -2136,7 +2136,7 @@ func (c *conn) submit(ctx context.Context, recvHdrFor func(string) string, msgWr
qml := make([]queue.Msg, len(c.recipients)) qml := make([]queue.Msg, len(c.recipients))
for i, rcpt := range c.recipients { for i, rcpt := range c.recipients {
if Localserve { if Localserve {
code, timeout := mox.LocalserveNeedsError(rcpt.addr.Localpart) code, timeout := mox.LocalserveNeedsError(rcpt.Addr.Localpart)
if timeout { if timeout {
c.log.Info("timing out submission due to special localpart") c.log.Info("timing out submission due to special localpart")
mox.Sleep(mox.Context, time.Hour) mox.Sleep(mox.Context, time.Hour)
@ -2160,11 +2160,11 @@ func (c *conn) submit(ctx context.Context, recvHdrFor func(string) string, msgWr
// messages in a single smtp transaction. // messages in a single smtp transaction.
var rcptTo string var rcptTo string
if len(c.recipients) == 1 { if len(c.recipients) == 1 {
rcptTo = rcpt.addr.String() rcptTo = rcpt.Addr.String()
} }
xmsgPrefix := append([]byte(recvHdrFor(rcptTo)), msgPrefix...) xmsgPrefix := append([]byte(recvHdrFor(rcptTo)), msgPrefix...)
msgSize := int64(len(xmsgPrefix)) + msgWriter.Size msgSize := int64(len(xmsgPrefix)) + msgWriter.Size
qm := queue.MakeMsg(fp, rcpt.addr, msgWriter.Has8bit, c.msgsmtputf8, msgSize, messageID, xmsgPrefix, c.requireTLS, now, header.Get("Subject")) qm := queue.MakeMsg(fp, rcpt.Addr, msgWriter.Has8bit, c.msgsmtputf8, msgSize, messageID, xmsgPrefix, c.requireTLS, now, header.Get("Subject"))
if !c.futureRelease.IsZero() { if !c.futureRelease.IsZero() {
qm.NextAttempt = c.futureRelease qm.NextAttempt = c.futureRelease
qm.FutureReleaseRequest = c.futureReleaseRequest qm.FutureReleaseRequest = c.futureReleaseRequest
@ -2190,7 +2190,7 @@ func (c *conn) submit(ctx context.Context, recvHdrFor func(string) string, msgWr
for i, rcpt := range c.recipients { for i, rcpt := range c.recipients {
c.log.Info("messages queued for delivery", c.log.Info("messages queued for delivery",
slog.Any("mailfrom", *c.mailFrom), slog.Any("mailfrom", *c.mailFrom),
slog.Any("rcptto", rcpt.addr), slog.Any("rcptto", rcpt.Addr),
slog.Bool("smtputf8", c.smtputf8), slog.Bool("smtputf8", c.smtputf8),
slog.Bool("msgsmtputf8", c.msgsmtputf8), slog.Bool("msgsmtputf8", c.msgsmtputf8),
slog.Int64("msgsize", qml[i].Size)) slog.Int64("msgsize", qml[i].Size))
@ -2198,7 +2198,7 @@ func (c *conn) submit(ctx context.Context, recvHdrFor func(string) string, msgWr
err = c.account.DB.Write(ctx, func(tx *bstore.Tx) error { err = c.account.DB.Write(ctx, func(tx *bstore.Tx) error {
for _, rcpt := range c.recipients { for _, rcpt := range c.recipients {
outgoing := store.Outgoing{Recipient: rcpt.addr.XString(true)} outgoing := store.Outgoing{Recipient: rcpt.Addr.XString(true)}
if err := tx.Insert(&outgoing); err != nil { if err := tx.Insert(&outgoing); err != nil {
return fmt.Errorf("adding outgoing message: %v", err) return fmt.Errorf("adding outgoing message: %v", err)
} }
@ -2418,7 +2418,7 @@ func (c *conn) deliver(ctx context.Context, recvHdrFor func(string) string, msgW
// Give immediate response if all recipients are unknown. // Give immediate response if all recipients are unknown.
nunknown := 0 nunknown := 0
for _, r := range c.recipients { for _, r := range c.recipients {
if r.account == nil && r.alias == nil { if r.Account == nil && r.Alias == nil {
nunknown++ nunknown++
} }
} }
@ -2653,7 +2653,7 @@ func (c *conn) deliver(ctx context.Context, recvHdrFor func(string) string, msgW
} }
var deliverErrors []deliverError var deliverErrors []deliverError
addError := func(rcpt recipient, code int, secode string, userError bool, errmsg string) { addError := func(rcpt recipient, code int, secode string, userError bool, errmsg string) {
e := deliverError{rcpt.addr, code, secode, userError, errmsg} e := deliverError{rcpt.Addr, code, secode, userError, errmsg}
c.log.Info("deliver error", c.log.Info("deliver error",
slog.Any("rcptto", e.rcptTo), slog.Any("rcptto", e.rcptTo),
slog.Int("code", code), slog.Int("code", code),
@ -2666,9 +2666,9 @@ func (c *conn) deliver(ctx context.Context, recvHdrFor func(string) string, msgW
// Sort recipients: local accounts, aliases, unknown. For ensuring we don't deliver // Sort recipients: local accounts, aliases, unknown. For ensuring we don't deliver
// to an alias destination that was also explicitly sent to. // to an alias destination that was also explicitly sent to.
rcptScore := func(r recipient) int { rcptScore := func(r recipient) int {
if r.account != nil { if r.Account != nil {
return 0 return 0
} else if r.alias != nil { } else if r.Alias != nil {
return 1 return 1
} }
return 2 return 2
@ -2682,9 +2682,9 @@ func (c *conn) deliver(ctx context.Context, recvHdrFor func(string) string, msgW
// addressee. Relies on c.recipients being sorted as above. // addressee. Relies on c.recipients being sorted as above.
regularRecipient := func(addr smtp.Path) bool { regularRecipient := func(addr smtp.Path) bool {
for _, rcpt := range c.recipients { for _, rcpt := range c.recipients {
if rcpt.account == nil { if rcpt.Account == nil {
break break
} else if rcpt.addr.Equal(addr) { } else if rcpt.Addr.Equal(addr) {
return true return true
} }
} }
@ -2761,7 +2761,7 @@ func (c *conn) deliver(ctx context.Context, recvHdrFor func(string) string, msgW
// we will consider a message delivered if we delivered it to at least one account // we will consider a message delivered if we delivered it to at least one account
// (others may be over quota). // (others may be over quota).
processRecipient := func(rcpt recipient) { processRecipient := func(rcpt recipient) {
log := c.log.With(slog.Any("mailfrom", c.mailFrom), slog.Any("rcptto", rcpt.addr)) log := c.log.With(slog.Any("mailfrom", c.mailFrom), slog.Any("rcptto", rcpt.Addr))
// If this is not a valid local user, we send back a DSN. This can only happen when // If this is not a valid local user, we send back a DSN. This can only happen when
// there are also valid recipients, and only when remote is SPF-verified, so the DSN // there are also valid recipients, and only when remote is SPF-verified, so the DSN
@ -2771,7 +2771,7 @@ func (c *conn) deliver(ctx context.Context, recvHdrFor func(string) string, msgW
// deliveries, and return an error at the end? Though the failure conditions will // deliveries, and return an error at the end? Though the failure conditions will
// probably prevent any other successful deliveries too... // probably prevent any other successful deliveries too...
// We'll continue delivering to other recipients. ../rfc/5321:3275 // We'll continue delivering to other recipients. ../rfc/5321:3275
if rcpt.account == nil && rcpt.alias == nil { if rcpt.Account == nil && rcpt.Alias == nil {
metricDelivery.WithLabelValues("unknownuser", "").Inc() metricDelivery.WithLabelValues("unknownuser", "").Inc()
addError(rcpt, smtp.C550MailboxUnavail, smtp.SeAddr1UnknownDestMailbox1, true, "no such user") addError(rcpt, smtp.C550MailboxUnavail, smtp.SeAddr1UnknownDestMailbox1, true, "no such user")
return return
@ -2792,17 +2792,17 @@ func (c *conn) deliver(ctx context.Context, recvHdrFor func(string) string, msgW
// check. We check all alias destinations, even if we already explicitly delivered // check. We check all alias destinations, even if we already explicitly delivered
// to them: they may be the only destination that would accept the message. // to them: they may be the only destination that would accept the message.
var a0 *analysis // Analysis we've used for accept/reject decision. var a0 *analysis // Analysis we've used for accept/reject decision.
if rcpt.alias != nil { if rcpt.Alias != nil {
// Check if msgFrom address is acceptable. This doesn't take validation into // Check if msgFrom address is acceptable. This doesn't take validation into
// consideration. If the header was forged, the message may be rejected later on. // consideration. If the header was forged, the message may be rejected later on.
if !aliasAllowedMsgFrom(rcpt.alias.alias, msgFrom) { if !aliasAllowedMsgFrom(rcpt.Alias.Alias, msgFrom) {
addError(rcpt, smtp.C550MailboxUnavail, smtp.SePol7ExpnProhibited2, true, "not allowed to send to destination") addError(rcpt, smtp.C550MailboxUnavail, smtp.SePol7ExpnProhibited2, true, "not allowed to send to destination")
return return
} }
la = make([]analysis, 0, len(rcpt.alias.alias.ParsedAddresses)) la = make([]analysis, 0, len(rcpt.Alias.Alias.ParsedAddresses))
for _, aa := range rcpt.alias.alias.ParsedAddresses { for _, aa := range rcpt.Alias.Alias.ParsedAddresses {
a, err := messageAnalyze(log, rcpt.addr, aa.Address.Path(), aa.AccountName, aa.Destination, rcpt.alias.canonicalAddress) a, err := messageAnalyze(log, rcpt.Addr, aa.Address.Path(), aa.AccountName, aa.Destination, rcpt.Alias.CanonicalAddress)
if err != nil { if err != nil {
addError(rcpt, smtp.C451LocalErr, smtp.SeSys3Other0, false, "error processing") addError(rcpt, smtp.C451LocalErr, smtp.SeSys3Other0, false, "error processing")
return return
@ -2818,7 +2818,7 @@ func (c *conn) deliver(ctx context.Context, recvHdrFor func(string) string, msgW
a0 = &la[0] a0 = &la[0]
} }
} else { } else {
a, err := messageAnalyze(log, rcpt.addr, rcpt.addr, rcpt.account.accountName, rcpt.account.destination, rcpt.account.canonicalAddress) a, err := messageAnalyze(log, rcpt.Addr, rcpt.Addr, rcpt.Account.AccountName, rcpt.Account.Destination, rcpt.Account.CanonicalAddress)
if err != nil { if err != nil {
addError(rcpt, smtp.C451LocalErr, smtp.SeSys3Other0, false, "error processing") addError(rcpt, smtp.C451LocalErr, smtp.SeSys3Other0, false, "error processing")
return return
@ -2893,7 +2893,7 @@ func (c *conn) deliver(ctx context.Context, recvHdrFor func(string) string, msgW
"Return-Path: <" + c.mailFrom.String() + ">\r\n" + // ../rfc/5321:3300 "Return-Path: <" + c.mailFrom.String() + ">\r\n" + // ../rfc/5321:3300
rcptAuthResults.Header() + rcptAuthResults.Header() +
receivedSPF.Header() + receivedSPF.Header() +
recvHdrFor(rcpt.addr.String()), recvHdrFor(rcpt.Addr.String()),
) )
la[i].d.m.Size += int64(len(la[i].d.m.MsgPrefix)) la[i].d.m.Size += int64(len(la[i].d.m.MsgPrefix))
} }
@ -2986,7 +2986,7 @@ func (c *conn) deliver(ctx context.Context, recvHdrFor func(string) string, msgW
Disposition: disposition, Disposition: disposition,
AlignedDKIMPass: dmarcResult.AlignedDKIMPass, AlignedDKIMPass: dmarcResult.AlignedDKIMPass,
AlignedSPFPass: dmarcResult.AlignedSPFPass, AlignedSPFPass: dmarcResult.AlignedSPFPass,
EnvelopeTo: rcpt.addr.IPDomain.String(), EnvelopeTo: rcpt.Addr.IPDomain.String(),
EnvelopeFrom: c.mailFrom.IPDomain.String(), EnvelopeFrom: c.mailFrom.IPDomain.String(),
HeaderFrom: msgFrom.Domain.Name(), HeaderFrom: msgFrom.Domain.Name(),
} }
@ -3034,7 +3034,7 @@ func (c *conn) deliver(ctx context.Context, recvHdrFor func(string) string, msgW
if !a0.accept { if !a0.accept {
for _, a := range la { for _, a := range la {
// Don't add message if address was also explicitly present in a RCPT TO command. // Don't add message if address was also explicitly present in a RCPT TO command.
if rcpt.alias != nil && regularRecipient(a.d.deliverTo) { if rcpt.Alias != nil && regularRecipient(a.d.deliverTo) {
continue continue
} }
@ -3084,7 +3084,7 @@ func (c *conn) deliver(ctx context.Context, recvHdrFor func(string) string, msgW
} }
delayFirstTime := true delayFirstTime := true
if rcpt.account != nil && a0.dmarcReport != nil { if rcpt.Account != nil && a0.dmarcReport != nil {
// todo future: add rate limiting to prevent DoS attacks. ../rfc/7489:2570 // todo future: add rate limiting to prevent DoS attacks. ../rfc/7489:2570
if err := dmarcdb.AddReport(ctx, a0.dmarcReport, msgFrom.Domain); err != nil { if err := dmarcdb.AddReport(ctx, a0.dmarcReport, msgFrom.Domain); err != nil {
log.Errorx("saving dmarc aggregate report in database", err) log.Errorx("saving dmarc aggregate report in database", err)
@ -3094,7 +3094,7 @@ func (c *conn) deliver(ctx context.Context, recvHdrFor func(string) string, msgW
delayFirstTime = false delayFirstTime = false
} }
} }
if rcpt.account != nil && a0.tlsReport != nil { if rcpt.Account != nil && a0.tlsReport != nil {
// todo future: add rate limiting to prevent DoS attacks. // todo future: add rate limiting to prevent DoS attacks.
if err := tlsrptdb.AddReport(ctx, c.log, msgFrom.Domain, c.mailFrom.String(), a0.d.destination.HostTLSReports, a0.tlsReport); err != nil { if err := tlsrptdb.AddReport(ctx, c.log, msgFrom.Domain, c.mailFrom.String(), a0.d.destination.HostTLSReports, a0.tlsReport); err != nil {
log.Errorx("saving TLSRPT report in database", err) log.Errorx("saving TLSRPT report in database", err)
@ -3115,7 +3115,7 @@ func (c *conn) deliver(ctx context.Context, recvHdrFor func(string) string, msgW
} }
if Localserve { if Localserve {
code, timeout := mox.LocalserveNeedsError(rcpt.addr.Localpart) code, timeout := mox.LocalserveNeedsError(rcpt.Addr.Localpart)
if timeout { if timeout {
log.Info("timing out due to special localpart") log.Info("timing out due to special localpart")
mox.Sleep(mox.Context, time.Hour) mox.Sleep(mox.Context, time.Hour)
@ -3147,7 +3147,7 @@ func (c *conn) deliver(ctx context.Context, recvHdrFor func(string) string, msgW
for _, a := range la { for _, a := range la {
// Don't deliver to recipient that was explicitly present in SMTP transaction, or // Don't deliver to recipient that was explicitly present in SMTP transaction, or
// is sending the message to an alias they are member of. // is sending the message to an alias they are member of.
if rcpt.alias != nil && (regularRecipient(a.d.deliverTo) || a.d.deliverTo.Equal(msgFrom.Path())) { if rcpt.Alias != nil && (regularRecipient(a.d.deliverTo) || a.d.deliverTo.Equal(msgFrom.Path())) {
continue continue
} }