make protocol trace logging optional, default off

1 files changed, 15 insertions, 4 deletions

diff --git a/ipp/ipp.go b/ipp/ipp.go
index e9c1430..391b094 100644
--- a/ipp/ipp.go
+++ b/ipp/ipp.go
@@ -3,6 +3,7 @@ package ipp
 import (
 	"encoding/binary"
 	"encoding/hex"
+	"flag"
 	"hash/crc32"
 	"io"
 	"log"
@@ -11,6 +12,8 @@ import (
 	"golang.org/x/sys/unix"
 )
 
+var Trace = flag.Bool("ipp-trace", false, "log IPP protocol traces")
+
 var crc8table = [256]byte{
 	0x00, 0x5e, 0xbc, 0xe2, 0x61, 0x3f, 0xdd, 0x83, 0xc2, 0x9c, 0x7e, 0x20, 0xa3, 0xfd, 0x1f, 0x41,
 	0x9d, 0xc3, 0x21, 0x7f, 0xfc, 0xa2, 0x40, 0x1e, 0x5f, 0x01, 0xe3, 0xbd, 0x3e, 0x60, 0x82, 0xdc,
@@ -107,7 +110,9 @@ func (s *session) handleMsg(bs []byte) (nRead int) {
 	}
 	msgType := bs[0]
 	if msgType != 0xbc {
-		log.Printf("skipping non-IPP message %s", hex.EncodeToString(bs))
+		if *Trace {
+			log.Printf("skipping non-IPP message %s", hex.EncodeToString(bs))
+		}
 		nRead = len(bs)
 		return
 	}
@@ -148,7 +153,9 @@ func (s *session) handleMsg(bs []byte) (nRead int) {
 	if ippLen > 0 {
 		ellipsis = "..."
 	}
-	log.Printf("%s < %s%s%s", s.path, hex.EncodeToString(bs[:7]), ellipsis, hex.EncodeToString(bs[7+ippLen:expectedLen]))
+	if *Trace {
+		log.Printf("%s < %s%s%s", s.path, hex.EncodeToString(bs[:7]), ellipsis, hex.EncodeToString(bs[7+ippLen:expectedLen]))
+	}
 	if s.handler != nil {
 		s.handler(ippType, ippData)
 	}
@@ -163,7 +170,9 @@ func (s *session) Close() error {
 }
 
 func (s *session) Write(bs []byte) (int, error) {
-	log.Printf("%s > %s", s.path, hex.EncodeToString(bs))
+	if *Trace {
+		log.Printf("%s > %s", s.path, hex.EncodeToString(bs))
+	}
 	return unix.Write(s.fd, bs)
 }
 
@@ -183,7 +192,9 @@ func (s *session) SendIPP(ippType byte, ippData []byte) error {
 		msgCRC = make([]byte, 4)
 		binary.LittleEndian.PutUint32(msgCRC, ^crc32.ChecksumIEEE(ippData))
 	}
-	log.Printf("%s > %s%s%s", s.path, hex.EncodeToString(ippHdr), hex.EncodeToString(ippData), hex.EncodeToString(msgCRC))
+	if *Trace {
+		log.Printf("%s > %s%s%s", s.path, hex.EncodeToString(ippHdr), hex.EncodeToString(ippData), hex.EncodeToString(msgCRC))
+	}
 	if _, err := unix.Writev(s.fd, [][]byte{ippHdr, ippData, msgCRC}); err != nil {
 		return err
 	}