From 579b48366c91a985f5944edc25d849f18afcebce Mon Sep 17 00:00:00 2001
From: Jordan Rife <jordan@jrife.io>
Date: Sat, 22 Feb 2025 17:28:57 -0800
Subject: [PATCH] netkit: Allow setting MAC address in L2 mode

Signed-off-by: Jordan Rife <jordan@jrife.io>
---
 link_linux.go |  7 +++++--
 link_test.go  | 16 ++++++++++++++--
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/link_linux.go b/link_linux.go
index 14dea596..889ce643 100644
--- a/link_linux.go
+++ b/link_linux.go
@@ -2671,8 +2671,8 @@ func (h *Handle) LinkSetGroup(link Link, group int) error {
 }
 
 func addNetkitAttrs(nk *Netkit, linkInfo *nl.RtAttr, flag int) error {
-	if nk.peerLinkAttrs.HardwareAddr != nil || nk.HardwareAddr != nil {
-		return fmt.Errorf("netkit doesn't support setting Ethernet")
+	if nk.Mode != NETKIT_MODE_L2 && (nk.LinkAttrs.HardwareAddr != nil || nk.peerLinkAttrs.HardwareAddr != nil) {
+		return fmt.Errorf("netkit only allows setting Ethernet in L2 mode")
 	}
 
 	data := linkInfo.AddRtAttr(nl.IFLA_INFO_DATA, nil)
@@ -2724,6 +2724,9 @@ func addNetkitAttrs(nk *Netkit, linkInfo *nl.RtAttr, flag int) error {
 			peer.AddRtAttr(unix.IFLA_NET_NS_FD, nl.Uint32Attr(uint32(ns)))
 		}
 	}
+	if nk.peerLinkAttrs.HardwareAddr != nil {
+		peer.AddRtAttr(unix.IFLA_ADDRESS, []byte(nk.peerLinkAttrs.HardwareAddr))
+	}
 	return nil
 }
 
diff --git a/link_test.go b/link_test.go
index 6b4a7b7c..425148ad 100644
--- a/link_test.go
+++ b/link_test.go
@@ -86,6 +86,11 @@ func testLinkAddDel(t *testing.T, link Link) {
 			if resultPrimary.SupportsScrub() && resultPrimary.PeerScrub != inputPrimary.PeerScrub {
 				t.Fatalf("Peer Scrub is %d, should be %d", int(resultPrimary.PeerScrub), int(inputPrimary.PeerScrub))
 			}
+			if inputPrimary.Mode == NETKIT_MODE_L2 && inputPrimary.HardwareAddr != nil {
+				if inputPrimary.HardwareAddr.String() != resultPrimary.HardwareAddr.String() {
+					t.Fatalf("Hardware address is %s, should be %s", resultPrimary.HardwareAddr.String(), inputPrimary.HardwareAddr.String())
+				}
+			}
 
 			if inputPrimary.peerLinkAttrs.Name != "" {
 				var resultPeer *Netkit
@@ -117,6 +122,11 @@ func testLinkAddDel(t *testing.T, link Link) {
 				if resultPrimary.Scrub != resultPeer.PeerScrub {
 					t.Fatalf("PeerScrub from peer is %d, should be %d", int(resultPeer.PeerScrub), int(resultPrimary.Scrub))
 				}
+				if inputPrimary.Mode == NETKIT_MODE_L2 && inputPrimary.peerLinkAttrs.HardwareAddr != nil {
+					if inputPrimary.peerLinkAttrs.HardwareAddr.String() != resultPeer.HardwareAddr.String() {
+						t.Fatalf("Peer hardware address is %s, should be %s", resultPeer.HardwareAddr.String(), inputPrimary.peerLinkAttrs.HardwareAddr.String())
+					}
+				}
 			}
 		}
 
@@ -1061,7 +1071,8 @@ func TestLinkAddDelNetkit(t *testing.T) {
 
 	netkit := &Netkit{
 		LinkAttrs: LinkAttrs{
-			Name: "foo",
+			Name:         "foo",
+			HardwareAddr: net.HardwareAddr{0x00, 0x11, 0x22, 0x33, 0x44, 0x55},
 		},
 		Mode:       NETKIT_MODE_L2,
 		Policy:     NETKIT_POLICY_FORWARD,
@@ -1070,7 +1081,8 @@ func TestLinkAddDelNetkit(t *testing.T) {
 		PeerScrub:  NETKIT_SCRUB_NONE,
 	}
 	peerAttr := &LinkAttrs{
-		Name: "bar",
+		Name:         "bar",
+		HardwareAddr: net.HardwareAddr{0x66, 0x77, 0x88, 0x99, 0xAA, 0xBB},
 	}
 	netkit.SetPeerAttrs(peerAttr)
 	testLinkAddDel(t, netkit)