feat: drop Trx.Log and WithSyslog from mailfilter

Trx.Log would just add the QueueId to your log string, that's not that much of a convenience to warrant the tight coupling with the log standard library. The implementation cannot be used with structured logging libraries so wen users of this library use a more sophisticated logging they cannot use this little helper anyway.

BREAKING CHANGE: you should bring your own logging

mailfilter/mailfilter.go

@@ -3,9 +3,6 @@ package mailfilter
 
 import (
 	"context"
-	"fmt"
-	"log"
-	"log/syslog"
 	"net"
 	"sync"
 
@@ -45,18 +42,6 @@ func New(network, address string, decision DecisionModificationFunc, opts ...Opt
 		o(&resolvedOptions)
 	}
 
-	if resolvedOptions.syslogPrefix != "" {
-		sysLogger, err := syslog.NewLogger(syslog.LOG_MAIL, 0)
-		if err != nil {
-			return nil, err
-		}
-		sysLogger.SetPrefix(resolvedOptions.syslogPrefix)
-		milter.LogWarning = func(format string, v ...interface{}) {
-			log.Printf(fmt.Sprintf("milter: warning: %s", format), v...)
-			sysLogger.Printf(format, v...)
-		}
-	}
-
 	actions := milter.AllClientSupportedActionMasks
 	protocols := milter.OptHeaderLeadingSpace | milter.OptNoUnknown
 

mailfilter/option.go

@@ -41,7 +41,6 @@ type options struct {
 	decisionAt    DecisionAt
 	errorHandling ErrorHandling
 	skipBody      bool
-	syslogPrefix  string
 }
 
 type Option func(opt *options)
@@ -68,12 +67,3 @@ func WithoutBody() Option {
 		opt.skipBody = true
 	}
 }
-
-// WithSyslog enables logging to syslog with a prefix of prefix.
-// This is a global option.
-// All calls to [github.com/d--j/go-milter.LogWarning] will be also send to the syslog.
-func WithSyslog(prefix string) Option {
-	return func(opt *options) {
-		opt.syslogPrefix = prefix
-	}
-}

mailfilter/testtrx/example_test.go

@@ -11,7 +11,6 @@ import (
 
 func Filter(_ context.Context, trx mailfilter.Trx) (mailfilter.Decision, error) {
 	trx.ChangeMailFrom("", "A=B")
-	trx.Log("test")
 	return mailfilter.Accept, nil
 }
 
@@ -48,8 +47,6 @@ func ExampleTrx() {
 	for _, m := range trx.Modifications() {
 		fmt.Println(m)
 	}
-	fmt.Println(trx.Logs())
 
 	// Output: {0  A=B 0   []}
-	// [test]
 }

mailfilter/testtrx/trx.go

@@ -3,7 +3,6 @@ package testtrx
 
 import (
 	"bytes"
-	"fmt"
 	"io"
 
 	"github.com/d--j/go-milter/internal/header"
@@ -51,7 +50,6 @@ type Trx struct {
 	rcptTos         []*addr.RcptTo
 	origRcptTos     []*addr.RcptTo
 	queueId         string
-	logs            []string
 	header          *header.Header
 	origHeader      *header.Header
 	body            io.ReadSeeker
@@ -187,14 +185,6 @@ func (t *Trx) SetQueueId(value string) *Trx {
 	return t
 }
 
-func (t *Trx) Log(format string, v ...any) {
-	t.logs = append(t.logs, fmt.Sprintf(format, v...))
-}
-
-func (t *Trx) Logs() []string {
-	return t.logs
-}
-
 func (t *Trx) Modifications() []Modification {
 	var mods []Modification
 	if t.origMailFrom.Addr != t.mailFrom.Addr || t.origMailFrom.Args != t.mailFrom.Args {

mailfilter/testtrx/trx_test.go

@@ -63,10 +63,4 @@ func TestTestTrx(t *testing.T) {
 	if !reflect.DeepEqual(m, expected) {
 		t.Fatalf("trx.Modifications() = %+v, want %+v", m, expected)
 	}
-
-	trx.Log("test")
-	expectedLogs := []string{"test"}
-	if got := trx.Logs(); !reflect.DeepEqual(got, expectedLogs) {
-		t.Fatalf("trx.Logs() = %+v, want %+v", got, expectedLogs)
-	}
 }

mailfilter/transaction.go

@@ -3,7 +3,6 @@ package mailfilter
 import (
 	"bytes"
 	"context"
-	"fmt"
 	"io"
 	"os"
 	"regexp"
@@ -83,16 +82,6 @@ func (t *transaction) QueueId() string {
 	return t.queueId
 }
 
-func (t *transaction) Log(format string, v ...any) {
-	if LogFunc != nil {
-		queueId := t.queueId
-		if queueId == "" {
-			queueId = "?"
-		}
-		LogFunc(fmt.Sprintf("[%s] %s", queueId, format), v...)
-	}
-}
-
 func (t *transaction) cleanup() {
 	t.headers = nil
 	t.origHeaders = nil

mailfilter/trx.go

@@ -2,7 +2,6 @@ package mailfilter
 
 import (
 	"io"
-	"log"
 
 	"github.com/d--j/go-milter/mailfilter/addr"
 	"github.com/d--j/go-milter/mailfilter/header"
@@ -66,12 +65,4 @@ type Trx interface {
 	//
 	// Only populated if [WithDecisionAt] is bigger than [DecisionAtMailFrom].
 	QueueId() string
-
-	// Log uses [LogFunc] to log the data. The [Trx.QueueId] will be prepended.
-	Log(format string, v ...any)
 }
-
-// LogFunc is the fmt.Printf-like function that [Trx.Log] uses.
-// You can overwrite this variable to use something different than [log.Printf].
-// If you assign nil to it, all [Trx.Log] calls are no-ops.
-var LogFunc = log.Printf