tc: drop logging

helper.go

@@ -54,3 +54,11 @@ func endianSwapUint32(in uint32) uint32 {
 		((in & 0x00FF0000) >> 8) |
 		((in & 0xFF000000) >> 24)
 }
+
+// bytesToInt32 converts an array for four bytes in big endian format to an integer.
+func bytesToInt32(b []byte) int32 {
+	if len(b) != 4 {
+		return 0
+	}
+	return int32(b[0])<<24 | int32(b[1])<<16 | int32(b[2])<<8 | int32(b[3])
+}

helper_test.go

@@ -140,3 +140,21 @@ func TestEndianSwapUint32(t *testing.T) {
 		}
 	}
 }
+
+func TestBytesToInt32(t *testing.T) {
+	tests := []struct {
+		in  []byte
+		out int32
+	}{
+		{in: []byte{0x1}, out: 0},
+		{in: []byte{0x0, 0x0, 0x0, 0x2a}, out: 42},
+	}
+
+	for _, test := range tests {
+		test := test
+		out := bytesToInt32(test.in)
+		if test.out != out {
+			t.Fatalf("%d != %d", test.out, out)
+		}
+	}
+}

tc.go

@@ -3,7 +3,6 @@ package tc
 import (
 	"context"
 	"fmt"
-	"log"
 	"time"
 
 	"github.com/florianl/go-tc/internal/unix"
@@ -27,8 +26,6 @@ var _ tcConn = &netlink.Conn{}
 // Tc represents a RTNETLINK wrapper
 type Tc struct {
 	con tcConn
-
-	logger *log.Logger
 }
 
 var nativeEndian = native.Endian
@@ -47,12 +44,6 @@ func Open(config *Config) (*Tc, error) {
 	}
 	tc.con = con
 
-	if config.Logger == nil {
-		tc.logger = setDummyLogger()
-	} else {
-		tc.logger = config.Logger
-	}
-
 	return &tc, nil
 }
 
@@ -107,9 +98,15 @@ func (tc *Tc) action(action int, flags netlink.HeaderFlags, msg interface{}, opt
 	}
 
 	for _, msg := range msgs {
-		if msg.Header.Type == netlink.Error {
-			// see https://www.infradead.org/~tgr/libnl/doc/core.html#core_errmsg
-			tc.logger.Printf("received netlink.Error in action()\n")
+		switch msg.Header.Type {
+		case netlink.Error:
+			errCode := bytesToInt32(msg.Data[:4])
+			// Check if the sucess message is embeded encoded as error code 0:
+			if errCode != 0 {
+				return fmt.Errorf("received error from netlink: %#v", msg)
+			}
+		case netlink.Overrun:
+			return fmt.Errorf("lost netlink data: %#v", msg)
 		}
 	}
 
@@ -294,7 +291,6 @@ func (tc *Tc) Monitor(ctx context.Context, deadline time.Duration, fn HookFunc)
 				return 0
 			}
 		}
-		tc.logger.Printf("Could not receive message: %v\n", err)
 		return 1
 	})
 }
@@ -362,12 +358,10 @@ func (tc *Tc) monitor(ctx context.Context, deadline time.Duration,
 			for _, msg := range msgs {
 				var monitored Object
 				if err := unmarshalStruct(msg.Data[:20], &monitored.Msg); err != nil {
-					tc.logger.Printf("could not extract tc.Msg from %v\n", msg.Data[:20])
 					continue
 				}
 				if err := extractTcmsgAttributes(int(msg.Header.Type), msg.Data[20:],
 					&monitored.Attribute); err != nil {
-					tc.logger.Printf("could not extract attributes from %v\n", msg.Data[20:36])
 					continue
 				}
 				if fn(uint16(msg.Header.Type), monitored) != 0 {

tc_linux_integration_test.go

@@ -6,7 +6,6 @@ package tc
 import (
 	"context"
 	"fmt"
-	"log"
 	"net"
 	"os"
 	"testing"
@@ -161,17 +160,6 @@ func TestSocket(t *testing.T) {
 			t.Fatalf("failed to close test socket: %v", err)
 		}
 	})
-	t.Run("with logger", func(t *testing.T) {
-		tc, err := Open(&Config{
-			Logger: log.Default(),
-		})
-		if err != nil {
-			t.Fatalf("failed to open netlink socket: %v", err)
-		}
-		if err = tc.Close(); err != nil {
-			t.Fatalf("failed to close test socket: %v", err)
-		}
-	})
 }
 
 func TestMonitorWithErrorFunc(t *testing.T) {