add helper for Filter.Msg.Info (#209)

Signed-off-by: Florian Lehner <dev@der-flo.net>

Author: florianl

core/handle.go

@@ -17,3 +17,12 @@ func SplitHandle(handle uint32) (major, minor uint32) {
 	minor = handle & handleMinMask
 	return major, minor
 }
+
+// FilterInfo is a simple helper to set the priority and protocol of the filter
+func FilterInfo(priority uint16, protocol uint16) uint32 {
+	return BuildHandle(uint32(priority), uint32(endianSwapUint16(protocol)))
+}
+
+func endianSwapUint16(in uint16) uint16 {
+	return (in << 8) | (in >> 8)
+}

core/handle_test.go

@@ -1,6 +1,10 @@
 package core
 
-import "testing"
+import (
+	"testing"
+
+	"github.com/florianl/go-tc/internal/unix"
+)
 
 // Tests out the HandleStr function
 func TestSplitHandle(t *testing.T) {
@@ -43,3 +47,30 @@ func TestBuildHandle(t *testing.T) {
 		})
 	}
 }
+
+func TestFilterInfo(t *testing.T) {
+	tests := map[string]struct {
+		prio  uint16
+		proto uint16
+		info  uint32
+	}{
+		"protocol ip prio 73": {
+			prio:  73,
+			proto: unix.ETH_P_IP,
+			info:  0x490008,
+		},
+		"protocol all prio 0": {
+			prio:  0,
+			proto: unix.ETH_P_ALL,
+			info:  768,
+		},
+	}
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			info := FilterInfo(tt.prio, tt.proto)
+			if info != tt.info {
+				t.Errorf("Expected 0x%x but got 0x%x", tt.info, info)
+			}
+		})
+	}
+}

example_flower_test.go

@@ -89,7 +89,7 @@ func ExampleFlower() {
 			Ifindex: uint32(devID.Index),
 			Handle:  0,
 			Parent:  tc.HandleIngress + 1,
-			Info:    768,
+			Info:    core.FilterInfo(0, unix.ETH_P_ALL),
 		},
 		tc.Attribute{
 			Kind: "flower",

example_test.go

@@ -164,7 +164,7 @@ func Example_cBPF() {
 			Ifindex: uint32(devID.Index),
 			Handle:  0,
 			Parent:  tc.HandleIngress,
-			Info:    0x300,
+			Info:    core.FilterInfo(0, unix.ETH_P_ALL),
 		},
 		tc.Attribute{
 			Kind: "bpf",
@@ -270,7 +270,7 @@ func ExampleU32() {
 			Ifindex: uint32(devID.Index),
 			Handle:  0,
 			Parent:  tc.HandleIngress,
-			Info:    0x300,
+			Info:    core.FilterInfo(0, unix.ETH_P_ALL),
 		},
 		tc.Attribute{
 			Kind: "bpf",

internal/unix/types_linux.go

@@ -51,3 +51,9 @@ const (
 	RTM_DELACTION = linux.RTM_DELACTION
 	RTM_GETACTION = linux.RTM_GETACTION
 )
+
+// For tests:
+const (
+	ETH_P_IP  = linux.ETH_P_IP
+	ETH_P_ALL = linux.ETH_P_ALL
+)

internal/unix/types_other.go

@@ -49,3 +49,8 @@ const (
 	RTM_DELACTION = 49
 	RTM_GETACTION = 50
 )
+
+const (
+	ETH_P_IP  = 0x800
+	ETH_P_ALL = 0x3
+)