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, 22 insertions, 10 deletions

diff --git a/pkg/tcpip/stack/forwarding_test.go b/pkg/tcpip/stack/forwarding_test.go
index 4908848e9..9f2fd8181 100644
--- a/pkg/tcpip/stack/forwarding_test.go
+++ b/pkg/tcpip/stack/forwarding_test.go
@@ -41,6 +41,8 @@ const (
 	protocolNumberOffset = 2
 )
 
+var _ NetworkEndpoint = (*fwdTestNetworkEndpoint)(nil)
+
 // fwdTestNetworkEndpoint is a network-layer protocol endpoint.
 // Headers of this protocol are fwdTestNetHeaderLen bytes, but we currently only
 // use the first three: destination address, source address, and transport
@@ -53,8 +55,6 @@ type fwdTestNetworkEndpoint struct {
 	dispatcher TransportDispatcher
 }
 
-var _ NetworkEndpoint = (*fwdTestNetworkEndpoint)(nil)
-
 func (*fwdTestNetworkEndpoint) Enable() *tcpip.Error {
 	return nil
 }
@@ -104,7 +104,7 @@ func (f *fwdTestNetworkEndpoint) MaxHeaderLength() uint16 {
 	return f.nic.MaxHeaderLength() + fwdTestNetHeaderLen
 }
 
-func (f *fwdTestNetworkEndpoint) PseudoHeaderChecksum(protocol tcpip.TransportProtocolNumber, dstAddr tcpip.Address) uint16 {
+func (*fwdTestNetworkEndpoint) PseudoHeaderChecksum(protocol tcpip.TransportProtocolNumber, dstAddr tcpip.Address) uint16 {
 	return 0
 }
 
@@ -124,7 +124,7 @@ func (f *fwdTestNetworkEndpoint) WritePacket(r *Route, gso *GSO, params NetworkH
 }
 
 // WritePackets implements LinkEndpoint.WritePackets.
-func (f *fwdTestNetworkEndpoint) WritePackets(r *Route, gso *GSO, pkts PacketBufferList, params NetworkHeaderParams) (int, *tcpip.Error) {
+func (*fwdTestNetworkEndpoint) WritePackets(r *Route, gso *GSO, pkts PacketBufferList, params NetworkHeaderParams) (int, *tcpip.Error) {
 	panic("not implemented")
 }
 
@@ -141,6 +141,21 @@ func (f *fwdTestNetworkEndpoint) Close() {
 	f.AddressableEndpointState.Cleanup()
 }
 
+// Stats implements stack.NetworkEndpoint.
+func (*fwdTestNetworkEndpoint) Stats() NetworkEndpointStats {
+	return &fwdTestNetworkEndpointStats{}
+}
+
+var _ NetworkEndpointStats = (*fwdTestNetworkEndpointStats)(nil)
+
+type fwdTestNetworkEndpointStats struct{}
+
+// IsNetworkEndpointStats implements stack.NetworkEndpointStats.
+func (*fwdTestNetworkEndpointStats) IsNetworkEndpointStats() {}
+
+var _ LinkAddressResolver = (*fwdTestNetworkProtocol)(nil)
+var _ NetworkProtocol = (*fwdTestNetworkProtocol)(nil)
+
 // fwdTestNetworkProtocol is a network-layer protocol that implements Address
 // resolution.
 type fwdTestNetworkProtocol struct {
@@ -158,18 +173,15 @@ type fwdTestNetworkProtocol struct {
 	}
 }
 
-var _ NetworkProtocol = (*fwdTestNetworkProtocol)(nil)
-var _ LinkAddressResolver = (*fwdTestNetworkProtocol)(nil)
-
-func (f *fwdTestNetworkProtocol) Number() tcpip.NetworkProtocolNumber {
+func (*fwdTestNetworkProtocol) Number() tcpip.NetworkProtocolNumber {
 	return fwdTestNetNumber
 }
 
-func (f *fwdTestNetworkProtocol) MinimumPacketSize() int {
+func (*fwdTestNetworkProtocol) MinimumPacketSize() int {
 	return fwdTestNetHeaderLen
 }
 
-func (f *fwdTestNetworkProtocol) DefaultPrefixLen() int {
+func (*fwdTestNetworkProtocol) DefaultPrefixLen() int {
 	return fwdTestNetDefaultPrefixLen
 }