Add support for alternative names

This commit add the support for alternative names. * exposing the attributes in the link object. * adding the add and delete functions * allow LinkByName() to also find devices by altname like `ip link` Signed-off-by: Sebastian Sch <sebassch@gmail.com>
vishvananda · Feb 20, 2024 · a008cbd · a008cbd
1 parent 5daafaf
commit a008cbd
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Showing 3 changed files with 159 additions and 13 deletions.
diff --git a/link.go b/link.go
@@ -33,6 +33,7 @@ type LinkAttrs struct {
 	MasterIndex    int         // must be the index of a bridge
 	Namespace      interface{} // nil | NsPid | NsFd
 	Alias          string
+	AltNames       []string
 	Statistics     *LinkStatistics
 	Promisc        int
 	Allmulti       int

diff --git a/link_linux.go b/link_linux.go
@@ -497,6 +497,58 @@ func (h *Handle) LinkSetAlias(link Link, name string) error {
 	return err
 }
 
+// LinkAddAltName adds a new alternative name for the link device.
+// Equivalent to: `ip link property add $link altname $name`
+func LinkAddAltName(link Link, name string) error {
+	return pkgHandle.LinkAddAltName(link, name)
+}
+
+// LinkAddAltName adds a new alternative name for the link device.
+// Equivalent to: `ip link property add $link altname $name`
+func (h *Handle) LinkAddAltName(link Link, name string) error {
+	base := link.Attrs()
+	h.ensureIndex(base)
+	req := h.newNetlinkRequest(unix.RTM_NEWLINKPROP, unix.NLM_F_ACK)
+
+	msg := nl.NewIfInfomsg(unix.AF_UNSPEC)
+	msg.Index = int32(base.Index)
+	req.AddData(msg)
+
+	data := nl.NewRtAttr(unix.IFLA_PROP_LIST|unix.NLA_F_NESTED, nil)
+	data.AddRtAttr(unix.IFLA_ALT_IFNAME, []byte(name))
+
+	req.AddData(data)
+
+	_, err := req.Execute(unix.NETLINK_ROUTE, 0)
+	return err
+}
+
+// LinkDelAltName delete an alternative name for the link device.
+// Equivalent to: `ip link property del $link altname $name`
+func LinkDelAltName(link Link, name string) error {
+	return pkgHandle.LinkDelAltName(link, name)
+}
+
+// LinkDelAltName delete an alternative name for the link device.
+// Equivalent to: `ip link property del $link altname $name`
+func (h *Handle) LinkDelAltName(link Link, name string) error {
+	base := link.Attrs()
+	h.ensureIndex(base)
+	req := h.newNetlinkRequest(unix.RTM_DELLINKPROP, unix.NLM_F_ACK)
+
+	msg := nl.NewIfInfomsg(unix.AF_UNSPEC)
+	msg.Index = int32(base.Index)
+	req.AddData(msg)
+
+	data := nl.NewRtAttr(unix.IFLA_PROP_LIST|unix.NLA_F_NESTED, nil)
+	data.AddRtAttr(unix.IFLA_ALT_IFNAME, []byte(name))
+
+	req.AddData(data)
+
+	_, err := req.Execute(unix.NETLINK_ROUTE, 0)
+	return err
+}
+
 // LinkSetHardwareAddr sets the hardware address of the link device.
 // Equivalent to: `ip link set $link address $hwaddr`
 func LinkSetHardwareAddr(link Link, hwaddr net.HardwareAddr) error {
@@ -996,28 +1048,28 @@ func LinkSetXdpFdWithFlags(link Link, fd, flags int) error {
 // LinkSetGSOMaxSegs sets the GSO maximum segment count of the link device.
 // Equivalent to: `ip link set $link gso_max_segs $maxSegs`
 func LinkSetGSOMaxSegs(link Link, maxSegs int) error {
-       return pkgHandle.LinkSetGSOMaxSegs(link, maxSegs)
+	return pkgHandle.LinkSetGSOMaxSegs(link, maxSegs)
 }
 
 // LinkSetGSOMaxSegs sets the GSO maximum segment count of the link device.
 // Equivalent to: `ip link set $link gso_max_segs $maxSegs`
 func (h *Handle) LinkSetGSOMaxSegs(link Link, maxSize int) error {
-       base := link.Attrs()
-       h.ensureIndex(base)
-       req := h.newNetlinkRequest(unix.RTM_SETLINK, unix.NLM_F_ACK)
+	base := link.Attrs()
+	h.ensureIndex(base)
+	req := h.newNetlinkRequest(unix.RTM_SETLINK, unix.NLM_F_ACK)
 
-       msg := nl.NewIfInfomsg(unix.AF_UNSPEC)
-       msg.Index = int32(base.Index)
-       req.AddData(msg)
+	msg := nl.NewIfInfomsg(unix.AF_UNSPEC)
+	msg.Index = int32(base.Index)
+	req.AddData(msg)
 
-       b := make([]byte, 4)
-       native.PutUint32(b, uint32(maxSize))
+	b := make([]byte, 4)
+	native.PutUint32(b, uint32(maxSize))
 
-       data := nl.NewRtAttr(unix.IFLA_GSO_MAX_SEGS, b)
-       req.AddData(data)
+	data := nl.NewRtAttr(unix.IFLA_GSO_MAX_SEGS, b)
+	req.AddData(data)
 
-       _, err := req.Execute(unix.NETLINK_ROUTE, 0)
-       return err
+	_, err := req.Execute(unix.NETLINK_ROUTE, 0)
+	return err
 }
 
 // LinkSetGSOMaxSize sets the IPv6 GSO maximum size of the link device.
@@ -1770,6 +1822,13 @@ func (h *Handle) linkByNameDump(name string) (Link, error) {
 		if link.Attrs().Name == name {
 			return link, nil
 		}
+
+		// support finding interfaces also via altnames
+		for _, altName := range link.Attrs().AltNames {
+			if altName == name {
+				return link, nil
+			}
+		}
 	}
 	return nil, LinkNotFoundError{fmt.Errorf("Link %s not found", name)}
 }
@@ -2136,6 +2195,18 @@ func LinkDeserialize(hdr *unix.NlMsghdr, m []byte) (Link, error) {
 				protinfo := parseProtinfo(attrs)
 				base.Protinfo = &protinfo
 			}
+		case unix.IFLA_PROP_LIST | unix.NLA_F_NESTED:
+			attrs, err := nl.ParseRouteAttr(attr.Value[:])
+			if err != nil {
+				return nil, err
+			}
+
+			base.AltNames = []string{}
+			for _, attr := range attrs {
+				if attr.Attr.Type == unix.IFLA_ALT_IFNAME {
+					base.AltNames = append(base.AltNames, nl.BytesToString(attr.Value))
+				}
+			}
 		case unix.IFLA_OPERSTATE:
 			base.OperState = LinkOperState(uint8(attr.Value[0]))
 		case unix.IFLA_PHYS_SWITCH_ID:

diff --git a/link_test.go b/link_test.go
@@ -1885,6 +1885,80 @@ func TestLinkSet(t *testing.T) {
 	}
 }
 
+func TestLinkAltName(t *testing.T) {
+	tearDown := setUpNetlinkTest(t)
+	defer tearDown()
+
+	iface := &Dummy{LinkAttrs{Name: "bar"}}
+	if err := LinkAdd(iface); err != nil {
+		t.Fatal(err)
+	}
+
+	link, err := LinkByName("bar")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = LinkAddAltName(link, "altname")
+	if err != nil {
+		t.Fatalf("Could not add altname: %v", err)
+	}
+
+	err = LinkAddAltName(link, "altname2")
+	if err != nil {
+		t.Fatalf("Could not add altname: %v", err)
+	}
+
+	link, err = LinkByName("bar")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	altNameExist := false
+	altName2Exist := false
+	for _, altName := range link.Attrs().AltNames {
+		if altName == "altname" {
+			altNameExist = true
+		} else if altName == "altname2" {
+			altName2Exist = true
+		}
+
+	}
+	if !altNameExist {
+		t.Fatal("Could not find altname")
+	}
+
+	if !altName2Exist {
+		t.Fatal("Could not find altname2")
+	}
+
+	link, err = LinkByName("altname")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	err = LinkDelAltName(link, "altname")
+	if err != nil {
+		t.Fatalf("Could not delete altname: %v", err)
+	}
+
+	link, err = LinkByName("bar")
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	altNameExist = false
+	for _, altName := range link.Attrs().AltNames {
+		if altName == "altname" {
+			altNameExist = true
+			break
+		}
+	}
+	if altNameExist {
+		t.Fatal("altname still exist")
+	}
+}
+
 func TestLinkSetARP(t *testing.T) {
 	tearDown := setUpNetlinkTest(t)
 	defer tearDown()