api: add IPAMClaimReference to network-selection-elements

Also add some unit tests to assert users cannot both request a
particular IP address and reference an IPAMClaim object at the same
time.

Signed-off-by: Miguel Duarte Barroso <mdbarroso@redhat.com>

pkg/apis/k8s.cni.cncf.io/v1/types.go

@@ -1,6 +1,8 @@
 package v1
 
 import (
+	"encoding/json"
+	"errors"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"net"
 )
@@ -162,6 +164,23 @@ type NetworkSelectionElement struct {
 	CNIArgs *map[string]interface{} `json:"cni-args,omitempty"`
 	// GatewayRequest contains default route IP address for the pod
 	GatewayRequest []net.IP `json:"default-route,omitempty"`
+	// IPAMClaimReference container the IPAMClaim name where the IPs for this
+	// attachment will be located.
+	IPAMClaimReference string `json:"ipam-claim-reference,omitempty"`
+}
+
+func (nse *NetworkSelectionElement) UnmarshalJSON(b []byte) error {
+	type networkSelectionElement NetworkSelectionElement
+
+	var netSelectionElement networkSelectionElement
+	if err := json.Unmarshal(b, &netSelectionElement); err != nil {
+		return err
+	}
+	if len(netSelectionElement.IPRequest) > 0 && netSelectionElement.IPAMClaimReference != "" {
+		return TooManyIPSources
+	}
+	*nse = NetworkSelectionElement(netSelectionElement)
+	return nil
 }
 
 const (
@@ -178,3 +197,5 @@ type NoK8sNetworkError struct {
 }
 
 func (e *NoK8sNetworkError) Error() string { return string(e.Message) }
+
+var TooManyIPSources = errors.New("cannot provide a static IP and a reference of an IPAM claim in the same network selection element")

pkg/apis/k8s.cni.cncf.io/v1/types_test.go

@@ -0,0 +1,60 @@
+package v1
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"reflect"
+	"testing"
+)
+
+type testCase struct {
+	description    string
+	input          string
+	expectedOutput NetworkSelectionElement
+	expectedError  error
+}
+
+func TestNetworkSelectionElementUnmarshaller(t *testing.T) {
+
+	testCases := []testCase{
+		{
+			description:   "ip request + IPAMClaims",
+			input:         "{\"name\":\"yo!\",\"ips\":[\"asd\"],\"ipam-claim-reference\":\"woop\"}",
+			expectedError: TooManyIPSources,
+		},
+		{
+			description: "successfully deserialize a simple struct",
+			input:       "{\"name\":\"yo!\",\"ips\":[\"an IP\"]}",
+			expectedOutput: NetworkSelectionElement{
+				Name:      "yo!",
+				IPRequest: []string{"an IP"},
+			},
+			expectedError: nil,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.description, func(t *testing.T) {
+			if err := run(tc); err != nil {
+				t.Errorf("failed test %q: %v", tc.description, err)
+			}
+		})
+	}
+}
+
+func run(tc testCase) error {
+	inputBytes := []byte(tc.input)
+
+	var nse NetworkSelectionElement
+	err := json.Unmarshal(inputBytes, &nse)
+	if tc.expectedError != nil {
+		if !errors.Is(err, tc.expectedError) {
+			return fmt.Errorf("unexpected error: %v. Expected error: %v", err, tc.expectedError)
+		}
+	}
+	if !reflect.DeepEqual(nse, tc.expectedOutput) {
+		return fmt.Errorf("parsed object is wrong: %v. Expected object: %v", nse, tc.expectedOutput)
+	}
+	return nil
+}