Per NIC NetworkEndpoint statistics

To facilitate the debugging of multi-homed setup, track Network
protocols statistics for each endpoint. Note that the original
stack-wide stats still exist.

A new type of statistic counter is introduced, which track two
versions of a stat at the same time. This lets a network endpoint
increment both the local stat and the stack-wide stat at the same
time.

Fixes #4605

PiperOrigin-RevId: 352663276

1 files changed, 14 insertions, 0 deletions

diff --git a/pkg/tcpip/network/arp/arp.go b/pkg/tcpip/network/arp/arp.go
index d54e7fe86..1d4d2966e 100644
--- a/pkg/tcpip/network/arp/arp.go
+++ b/pkg/tcpip/network/arp/arp.go
@@ -210,6 +210,20 @@ func (e *endpoint) HandlePacket(pkt *stack.PacketBuffer) {
 	}
 }
 
+// Stats implements stack.NetworkEndpoint.
+func (e *endpoint) Stats() stack.NetworkEndpointStats {
+	// TODO(gvisor.dev/issues/4963): Record statistics for ARP.
+	return &Stats{}
+}
+
+var _ stack.NetworkEndpointStats = (*Stats)(nil)
+
+// Stats holds ARP statistics.
+type Stats struct{}
+
+// IsNetworkEndpointStats implements stack.NetworkEndpointStats.
+func (*Stats) IsNetworkEndpointStats() {}
+
 // protocol implements stack.NetworkProtocol and stack.LinkAddressResolver.
 type protocol struct {
 	stack *stack.Stack