From 70def89fcbfb805a2a338c87400db2eeef132206 Mon Sep 17 00:00:00 2001
From: Christian Worm Mortensen <cworm@akamai.com>
Date: Wed, 31 Jan 2024 22:26:27 +0100
Subject: [PATCH] Allow link argument to AddrAdd, AddReplace and AddrDel to be
 nil

---
 addr_linux.go | 18 ++++++-----
 addr_test.go  | 89 +++++++++++++++++++++++++++------------------------
 2 files changed, 58 insertions(+), 49 deletions(-)

diff --git a/addr_linux.go b/addr_linux.go
index 7553a05..d8957d8 100644
--- a/addr_linux.go
+++ b/addr_linux.go
@@ -74,17 +74,19 @@ func (h *Handle) AddrDel(link Link, addr *Addr) error {
 }
 
 func (h *Handle) addrHandle(link Link, addr *Addr, req *nl.NetlinkRequest) error {
-	base := link.Attrs()
-	if addr.Label != "" && !strings.HasPrefix(addr.Label, base.Name) {
-		return fmt.Errorf("label must begin with interface name")
-	}
-	h.ensureIndex(base)
-
 	family := nl.GetIPFamily(addr.IP)
-
 	msg := nl.NewIfAddrmsg(family)
-	msg.Index = uint32(base.Index)
 	msg.Scope = uint8(addr.Scope)
+	if link == nil {
+		msg.Index = uint32(addr.LinkIndex)
+	} else {
+		base := link.Attrs()
+		if addr.Label != "" && !strings.HasPrefix(addr.Label, base.Name) {
+			return fmt.Errorf("label must begin with interface name")
+		}
+		h.ensureIndex(base)
+		msg.Index = uint32(base.Index)
+	}
 	mask := addr.Mask
 	if addr.Peer != nil {
 		mask = addr.Peer.Mask
diff --git a/addr_test.go b/addr_test.go
index 0a43212..d45a989 100644
--- a/addr_test.go
+++ b/addr_test.go
@@ -145,58 +145,65 @@ func TestAddrAddReplace(t *testing.T) {
 	tearDown := setUpNetlinkTest(t)
 	defer tearDown()
 
-	var address = &net.IPNet{IP: net.IPv4(127, 0, 0, 2), Mask: net.CIDRMask(24, 32)}
-	var addr = &Addr{IPNet: address}
+	for _, nilLink := range []bool{false, true} {
+		var address = &net.IPNet{IP: net.IPv4(127, 0, 0, 2), Mask: net.CIDRMask(24, 32)}
+		var addr = &Addr{IPNet: address}
 
-	link, err := LinkByName("lo")
-	if err != nil {
-		t.Fatal(err)
-	}
+		link, err := LinkByName("lo")
+		if err != nil {
+			t.Fatal(err)
+		}
 
-	err = AddrAdd(link, addr)
-	if err != nil {
-		t.Fatal(err)
-	}
+		if nilLink {
+			addr.LinkIndex = link.Attrs().Index
+			link = nil
+		}
 
-	addrs, err := AddrList(link, FAMILY_ALL)
-	if err != nil {
-		t.Fatal(err)
-	}
+		err = AddrAdd(link, addr)
+		if err != nil {
+			t.Fatal(err)
+		}
 
-	if len(addrs) != 1 {
-		t.Fatal("Address not added properly")
-	}
+		addrs, err := AddrList(link, FAMILY_ALL)
+		if err != nil {
+			t.Fatal(err)
+		}
 
-	err = AddrAdd(link, addr)
-	if err == nil {
-		t.Fatal("Re-adding address should fail (but succeeded unexpectedly).")
-	}
+		if len(addrs) != 1 {
+			t.Fatal("Address not added properly")
+		}
 
-	err = AddrReplace(link, addr)
-	if err != nil {
-		t.Fatal("Replacing address failed.")
-	}
+		err = AddrAdd(link, addr)
+		if err == nil {
+			t.Fatal("Re-adding address should fail (but succeeded unexpectedly).")
+		}
 
-	addrs, err = AddrList(link, FAMILY_ALL)
-	if err != nil {
-		t.Fatal(err)
-	}
+		err = AddrReplace(link, addr)
+		if err != nil {
+			t.Fatal("Replacing address failed.")
+		}
 
-	if len(addrs) != 1 {
-		t.Fatal("Address not added properly")
-	}
+		addrs, err = AddrList(link, FAMILY_ALL)
+		if err != nil {
+			t.Fatal(err)
+		}
 
-	if err = AddrDel(link, addr); err != nil {
-		t.Fatal(err)
-	}
+		if len(addrs) != 1 {
+			t.Fatal("Address not added properly")
+		}
 
-	addrs, err = AddrList(link, FAMILY_ALL)
-	if err != nil {
-		t.Fatal(err)
-	}
+		if err = AddrDel(link, addr); err != nil {
+			t.Fatal(err)
+		}
 
-	if len(addrs) != 0 {
-		t.Fatal("Address not removed properly")
+		addrs, err = AddrList(link, FAMILY_ALL)
+		if err != nil {
+			t.Fatal(err)
+		}
+
+		if len(addrs) != 0 {
+			t.Fatal("Address not removed properly")
+		}
 	}
 }