Add LinkAttrs constructor NewLinkAttrs

It looks little awkward, but should be enough for people who care about
defaults from kernel.

Fix #26

Also fixed bug with setting TxQLen for main device. It was never set
before.

Signed-off-by: Alexander Morozov <lk4d4@docker.com>

link.go

@@ -19,7 +19,7 @@ type (
 type LinkAttrs struct {
 	Index        int
 	MTU          int
-	TxQLen       uint32 // Transmit Queue Length
+	TxQLen       int // Transmit Queue Length
 	Name         string
 	HardwareAddr net.HardwareAddr
 	Flags        net.Flags
@@ -28,6 +28,13 @@ type LinkAttrs struct {
 	Namespace    interface{} // nil | NsPid | NsFd
 }
 
+// NewLinkAttrs returns LinkAttrs structure filled with default values
+func NewLinkAttrs() LinkAttrs {
+	return LinkAttrs{
+		TxQLen: -1,
+	}
+}
+
 // Device links cannot be created via netlink. These links
 // are links created by udev like 'lo' and 'etho0'
 type Device struct {

link_linux.go

@@ -321,6 +321,11 @@ func LinkAdd(link Link) error {
 		req.AddData(mtu)
 	}
 
+	if base.TxQLen >= 0 {
+		qlen := nl.NewRtAttr(syscall.IFLA_TXQLEN, nl.Uint32Attr(uint32(base.TxQLen)))
+		req.AddData(qlen)
+	}
+
 	if base.Namespace != nil {
 		var attr *nl.RtAttr
 		switch base.Namespace.(type) {
@@ -338,8 +343,6 @@ func LinkAdd(link Link) error {
 	linkInfo := nl.NewRtAttr(syscall.IFLA_LINKINFO, nil)
 	nl.NewRtAttrChild(linkInfo, nl.IFLA_INFO_KIND, nl.NonZeroTerminated(link.Type()))
 
-	nl.NewRtAttrChild(linkInfo, syscall.IFLA_TXQLEN, nl.Uint32Attr(base.TxQLen))
-
 	if vlan, ok := link.(*Vlan); ok {
 		b := make([]byte, 2)
 		native.PutUint16(b, uint16(vlan.VlanId))
@@ -350,10 +353,13 @@ func LinkAdd(link Link) error {
 		peer := nl.NewRtAttrChild(data, nl.VETH_INFO_PEER, nil)
 		nl.NewIfInfomsgChild(peer, syscall.AF_UNSPEC)
 		nl.NewRtAttrChild(peer, syscall.IFLA_IFNAME, nl.ZeroTerminated(veth.PeerName))
-		nl.NewRtAttrChild(peer, syscall.IFLA_TXQLEN, nl.Uint32Attr(base.TxQLen))
+		if base.TxQLen >= 0 {
+			nl.NewRtAttrChild(peer, syscall.IFLA_TXQLEN, nl.Uint32Attr(uint32(base.TxQLen)))
+		}
 		if base.MTU > 0 {
 			nl.NewRtAttrChild(peer, syscall.IFLA_MTU, nl.Uint32Attr(uint32(base.MTU)))
 		}
+
 	} else if vxlan, ok := link.(*Vxlan); ok {
 		addVxlanAttrs(vxlan, linkInfo)
 	} else if ipv, ok := link.(*IPVlan); ok {
@@ -552,7 +558,7 @@ func linkDeserialize(m []byte) (Link, error) {
 		case syscall.IFLA_MASTER:
 			base.MasterIndex = int(native.Uint32(attr.Value[0:4]))
 		case syscall.IFLA_TXQLEN:
-			base.TxQLen = native.Uint32(attr.Value[0:4])
+			base.TxQLen = int(native.Uint32(attr.Value[0:4]))
 		}
 	}
 	// Links that don't have IFLA_INFO_KIND are hardware devices

link_test.go

@@ -8,7 +8,10 @@ import (
 	"github.com/vishvananda/netns"
 )
 
-const testTxQLen uint32 = 100
+const (
+	testTxQLen    int = 100
+	defaultTxQLen int = 1000
+)
 
 func testLinkAddDel(t *testing.T, link Link) {
 	links, err := LinkList()
@@ -50,9 +53,9 @@ func testLinkAddDel(t *testing.T, link Link) {
 		}
 	}
 
-	if veth, ok := link.(*Veth); ok {
+	if veth, ok := result.(*Veth); ok {
-		if veth.TxQLen != testTxQLen {
+		if rBase.TxQLen != base.TxQLen {
-			t.Fatalf("TxQLen is %d, should be %d", veth.TxQLen, testTxQLen)
+			t.Fatalf("qlen is %d, should be %d", rBase.TxQLen, base.TxQLen)
 		}
 		if rBase.MTU != base.MTU {
 			t.Fatalf("MTU is %d, should be %d", rBase.MTU, base.MTU)
@@ -226,6 +229,99 @@ func TestLinkAddDelVeth(t *testing.T) {
 	testLinkAddDel(t, &Veth{LinkAttrs{Name: "foo", TxQLen: testTxQLen, MTU: 1400}, "bar"})
 }
 
+func TestLinkAddVethWithDefaultTxQLen(t *testing.T) {
+	tearDown := setUpNetlinkTest(t)
+	defer tearDown()
+	la := NewLinkAttrs()
+	la.Name = "foo"
+
+	veth := &Veth{LinkAttrs: la, PeerName: "bar"}
+	if err := LinkAdd(veth); err != nil {
+		t.Fatal(err)
+	}
+	link, err := LinkByName("foo")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if veth, ok := link.(*Veth); !ok {
+		t.Fatalf("unexpected link type: %T", link)
+	} else {
+		if veth.TxQLen != defaultTxQLen {
+			t.Fatalf("TxQLen is %d, should be %d", veth.TxQLen, defaultTxQLen)
+		}
+	}
+	peer, err := LinkByName("bar")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if veth, ok := peer.(*Veth); !ok {
+		t.Fatalf("unexpected link type: %T", link)
+	} else {
+		if veth.TxQLen != defaultTxQLen {
+			t.Fatalf("TxQLen is %d, should be %d", veth.TxQLen, defaultTxQLen)
+		}
+	}
+}
+
+func TestLinkAddVethWithZeroTxQLen(t *testing.T) {
+	tearDown := setUpNetlinkTest(t)
+	defer tearDown()
+	la := NewLinkAttrs()
+	la.Name = "foo"
+	la.TxQLen = 0
+
+	veth := &Veth{LinkAttrs: la, PeerName: "bar"}
+	if err := LinkAdd(veth); err != nil {
+		t.Fatal(err)
+	}
+	link, err := LinkByName("foo")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if veth, ok := link.(*Veth); !ok {
+		t.Fatalf("unexpected link type: %T", link)
+	} else {
+		if veth.TxQLen != 0 {
+			t.Fatalf("TxQLen is %d, should be %d", veth.TxQLen, 0)
+		}
+	}
+	peer, err := LinkByName("bar")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if veth, ok := peer.(*Veth); !ok {
+		t.Fatalf("unexpected link type: %T", link)
+	} else {
+		if veth.TxQLen != 0 {
+			t.Fatalf("TxQLen is %d, should be %d", veth.TxQLen, 0)
+		}
+	}
+}
+
+func TestLinkAddDummyWithTxQLen(t *testing.T) {
+	tearDown := setUpNetlinkTest(t)
+	defer tearDown()
+	la := NewLinkAttrs()
+	la.Name = "foo"
+	la.TxQLen = 1500
+
+	dummy := &Dummy{LinkAttrs: la}
+	if err := LinkAdd(dummy); err != nil {
+		t.Fatal(err)
+	}
+	link, err := LinkByName("foo")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if dummy, ok := link.(*Dummy); !ok {
+		t.Fatalf("unexpected link type: %T", link)
+	} else {
+		if dummy.TxQLen != 1500 {
+			t.Fatalf("TxQLen is %d, should be %d", dummy.TxQLen, 1500)
+		}
+	}
+}
+
 func TestLinkAddDelBridgeMaster(t *testing.T) {
 	tearDown := setUpNetlinkTest(t)
 	defer tearDown()