rate-limiter: add getRateLimiter/setRateLimiter in endpoint

We use tc-based or built-in rate limiter to shape network I/O traffic
and they all must be tied to one specific interface/endpoint.
In order to tell whether we've ever added rate limiter to this interface/endpoint,
we create get/set func to reveal/store such info.

Fixes: #250

Signed-off-by: Penny Zheng <penny.zheng@arm.com>

src/runtime/virtcontainers/tap_endpoint.go

@@ -21,6 +21,8 @@ type TapEndpoint struct {
 	EndpointProperties NetworkInfo
 	EndpointType       EndpointType
 	PCIAddr            string
+	RxRateLimiter      bool
+	TxRateLimiter      bool
 }
 
 // Properties returns the properties of the tap interface.
@@ -207,3 +209,21 @@ func (endpoint *TapEndpoint) load(s persistapi.NetworkEndpoint) {
 		endpoint.TapInterface = *tapif
 	}
 }
+
+func (endpoint *TapEndpoint) GetRxRateLimiter() bool {
+	return endpoint.RxRateLimiter
+}
+
+func (endpoint *TapEndpoint) SetRxRateLimiter() error {
+	endpoint.RxRateLimiter = true
+	return nil
+}
+
+func (endpoint *TapEndpoint) GetTxRateLimiter() bool {
+	return endpoint.TxRateLimiter
+}
+
+func (endpoint *TapEndpoint) SetTxRateLimiter() error {
+	endpoint.TxRateLimiter = true
+	return nil
+}