9 files changed, 58 insertions, 0 deletions
diff --git a/pkg/tcpip/link/channel/channel.go b/pkg/tcpip/link/channel/channel.go
index 20b183da0..a2bb773d4 100644
--- a/pkg/tcpip/link/channel/channel.go
+++ b/pkg/tcpip/link/channel/channel.go
@@ -23,6 +23,7 @@ import (
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
 )
 
@@ -296,3 +297,8 @@ func (e *Endpoint) AddNotify(notify Notification) *NotificationHandle {
 func (e *Endpoint) RemoveNotify(handle *NotificationHandle) {
 	e.q.RemoveNotify(handle)
 }
+
+// ARPHardwareType implements stack.LinkEndpoint.ARPHardwareType.
+func (*Endpoint) ARPHardwareType() header.ARPHardwareType {
+	return header.ARPHardwareNone
+}
diff --git a/pkg/tcpip/link/fdbased/endpoint.go b/pkg/tcpip/link/fdbased/endpoint.go
index f34082e1a..32abe2a13 100644
--- a/pkg/tcpip/link/fdbased/endpoint.go
+++ b/pkg/tcpip/link/fdbased/endpoint.go
@@ -626,6 +626,14 @@ func (e *endpoint) GSOMaxSize() uint32 {
 	return e.gsoMaxSize
 }
 
+// ARPHardwareType implements stack.LinkEndpoint.ARPHardwareType.
+func (e *endpoint) ARPHardwareType() header.ARPHardwareType {
+	if e.hdrSize > 0 {
+		return header.ARPHardwareEther
+	}
+	return header.ARPHardwareNone
+}
+
 // InjectableEndpoint is an injectable fd-based endpoint. The endpoint writes
 // to the FD, but does not read from it. All reads come from injected packets.
 type InjectableEndpoint struct {
diff --git a/pkg/tcpip/link/loopback/loopback.go b/pkg/tcpip/link/loopback/loopback.go
index 568c6874f..3b17d8c28 100644
--- a/pkg/tcpip/link/loopback/loopback.go
+++ b/pkg/tcpip/link/loopback/loopback.go
@@ -113,3 +113,8 @@ func (e *endpoint) WriteRawPacket(vv buffer.VectorisedView) *tcpip.Error {
 
 	return nil
 }
+
+// ARPHardwareType implements stack.LinkEndpoint.ARPHardwareType.
+func (*endpoint) ARPHardwareType() header.ARPHardwareType {
+	return header.ARPHardwareLoopback
+}
diff --git a/pkg/tcpip/link/muxed/injectable.go b/pkg/tcpip/link/muxed/injectable.go
index c69d6b7e9..c305d9e86 100644
--- a/pkg/tcpip/link/muxed/injectable.go
+++ b/pkg/tcpip/link/muxed/injectable.go
@@ -18,6 +18,7 @@ package muxed
 import (
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
 )
 
@@ -129,6 +130,11 @@ func (m *InjectableEndpoint) Wait() {
 	}
 }
 
+// ARPHardwareType implements stack.LinkEndpoint.ARPHardwareType.
+func (*InjectableEndpoint) ARPHardwareType() header.ARPHardwareType {
+	panic("unsupported operation")
+}
+
 // NewInjectableEndpoint creates a new multi-endpoint injectable endpoint.
 func NewInjectableEndpoint(routes map[tcpip.Address]stack.InjectableLinkEndpoint) *InjectableEndpoint {
 	return &InjectableEndpoint{
diff --git a/pkg/tcpip/link/nested/nested.go b/pkg/tcpip/link/nested/nested.go
index 2998f9c4f..328bd048e 100644
--- a/pkg/tcpip/link/nested/nested.go
+++ b/pkg/tcpip/link/nested/nested.go
@@ -20,6 +20,7 @@ import (
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
 )
 
@@ -129,3 +130,8 @@ func (e *Endpoint) GSOMaxSize() uint32 {
 	}
 	return 0
 }
+
+// ARPHardwareType implements stack.LinkEndpoint.ARPHardwareType
+func (e *Endpoint) ARPHardwareType() header.ARPHardwareType {
+	return e.child.ARPHardwareType()
+}
diff --git a/pkg/tcpip/link/qdisc/fifo/endpoint.go b/pkg/tcpip/link/qdisc/fifo/endpoint.go
index b5dfb7850..c84fe1bb9 100644
--- a/pkg/tcpip/link/qdisc/fifo/endpoint.go
+++ b/pkg/tcpip/link/qdisc/fifo/endpoint.go
@@ -22,6 +22,7 @@ import (
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
 )
 
@@ -207,3 +208,8 @@ func (e *endpoint) Wait() {
 
 	e.wg.Wait()
 }
+
+// ARPHardwareType implements stack.LinkEndpoint.ARPHardwareType
+func (e *endpoint) ARPHardwareType() header.ARPHardwareType {
+	return e.lower.ARPHardwareType()
+}
diff --git a/pkg/tcpip/link/sharedmem/sharedmem.go b/pkg/tcpip/link/sharedmem/sharedmem.go
index 0374a2441..a36862c67 100644
--- a/pkg/tcpip/link/sharedmem/sharedmem.go
+++ b/pkg/tcpip/link/sharedmem/sharedmem.go
@@ -287,3 +287,8 @@ func (e *endpoint) dispatchLoop(d stack.NetworkDispatcher) {
 
 	e.completed.Done()
 }
+
+// ARPHardwareType implements stack.LinkEndpoint.ARPHardwareType
+func (*endpoint) ARPHardwareType() header.ARPHardwareType {
+	return header.ARPHardwareEther
+}
diff --git a/pkg/tcpip/link/tun/device.go b/pkg/tcpip/link/tun/device.go
index 6bc9033d0..47446efec 100644
--- a/pkg/tcpip/link/tun/device.go
+++ b/pkg/tcpip/link/tun/device.go
@@ -139,6 +139,7 @@ func attachOrCreateNIC(s *stack.Stack, name, prefix string, linkCaps stack.LinkE
 			stack:    s,
 			nicID:    id,
 			name:     name,
+			isTap:    prefix == "tap",
 		}
 		endpoint.Endpoint.LinkEPCapabilities = linkCaps
 		if endpoint.name == "" {
@@ -348,6 +349,7 @@ type tunEndpoint struct {
 	stack *stack.Stack
 	nicID tcpip.NICID
 	name  string
+	isTap bool
 }
 
 // DecRef decrements refcount of e, removes NIC if refcount goes to 0.
@@ -356,3 +358,11 @@ func (e *tunEndpoint) DecRef() {
 		e.stack.RemoveNIC(e.nicID)
 	})
 }
+
+// ARPHardwareType implements stack.LinkEndpoint.ARPHardwareType.
+func (e *tunEndpoint) ARPHardwareType() header.ARPHardwareType {
+	if e.isTap {
+		return header.ARPHardwareEther
+	}
+	return header.ARPHardwareNone
+}
diff --git a/pkg/tcpip/link/waitable/waitable.go b/pkg/tcpip/link/waitable/waitable.go
index 949b3f2b2..24a8dc2eb 100644
--- a/pkg/tcpip/link/waitable/waitable.go
+++ b/pkg/tcpip/link/waitable/waitable.go
@@ -25,6 +25,7 @@ import (
 	"gvisor.dev/gvisor/pkg/gate"
 	"gvisor.dev/gvisor/pkg/tcpip"
 	"gvisor.dev/gvisor/pkg/tcpip/buffer"
+	"gvisor.dev/gvisor/pkg/tcpip/header"
 	"gvisor.dev/gvisor/pkg/tcpip/stack"
 )
 
@@ -147,3 +148,8 @@ func (e *Endpoint) WaitDispatch() {
 
 // Wait implements stack.LinkEndpoint.Wait.
 func (e *Endpoint) Wait() {}
+
+// ARPHardwareType implements stack.LinkEndpoint.ARPHardwareType.
+func (e *Endpoint) ARPHardwareType() header.ARPHardwareType {
+	return e.lower.ARPHardwareType()
+}