fix: deduplicate VRF/host-interface checks in cmdCheck and cmdStatus

Extract the duplicated VRF existence and host-interface existence checks
shared between cmdCheck and cmdStatus into a single checkNodeLevelState
helper. Both operations previously ran the same vrf.Exists() +
netlink.LinkByName() sequence with identical error formatting, creating
a maintenance risk for future drift.

- Extract checkNodeLevelState helper that validates VRF and host interface
  existence, returning the host interface name and accumulated errors
- Replace inline VRF/host checks in cmdCheck with a call to the helper
- Replace inline VRF/host checks in cmdStatus with a call to the helper
- Preserve hostName return value in cmdCheck for subsequent prevResult
  validation without duplicating GenerateInterfaceNameHost

fixes #168

Author: privateip

internal/cni/ops_check.go

@@ -37,16 +37,9 @@ func cmdCheck(args *skel.CmdArgs) error {
 
 	var errs []error
 
-	// Check VRF interface exists.
-	if err := vrf.Exists(pluginConf.VPC, pluginConf.VPCAttachment); err != nil {
-		errs = append(errs, fmt.Errorf("vrf %s-%s: %w", pluginConf.VPC, pluginConf.VPCAttachment, err))
-	}
-
-	// Check the host-side interface exists.
-	hostName := intf.GenerateInterfaceNameHost(pluginConf.VPC, pluginConf.VPCAttachment)
-	if _, err := netlink.LinkByName(hostName); err != nil {
-		errs = append(errs, fmt.Errorf("host interface %q: %w", hostName, err))
-	}
+	// Check node-level state (VRF + host interface).
+	hostName, nodeErrs := checkNodeLevelState(pluginConf.VPC, pluginConf.VPCAttachment)
+	errs = append(errs, nodeErrs...)
 
 	// For veth mode, verify the guest interface is in the container netns.
 	if pluginConf.InterfaceType == interfaceTypeVeth {
@@ -88,16 +81,9 @@ func cmdStatus(args *skel.CmdArgs) error {
 
 	var errs []error
 
-	// Check VRF interface exists.
-	if err := vrf.Exists(pluginConf.VPC, pluginConf.VPCAttachment); err != nil {
-		errs = append(errs, fmt.Errorf("vrf %s-%s: %w", pluginConf.VPC, pluginConf.VPCAttachment, err))
-	}
-
-	// Check the host-side interface exists.
-	hostName := intf.GenerateInterfaceNameHost(pluginConf.VPC, pluginConf.VPCAttachment)
-	if _, err := netlink.LinkByName(hostName); err != nil {
-		errs = append(errs, fmt.Errorf("host interface %q: %w", hostName, err))
-	}
+	// Check node-level state (VRF + host interface).
+	_, statusErrs := checkNodeLevelState(pluginConf.VPC, pluginConf.VPCAttachment)
+	errs = append(errs, statusErrs...)
 
 	// Check API server reachability with a lightweight GET.
 	if err := probeAPIServer(); err != nil {
@@ -144,6 +130,26 @@ func probeAPIServer() error {
 	return nil
 }
 
+// checkNodeLevelState verifies that node-level networking resources exist:
+// the VRF interface and the host-side endpoint interface. Returns the host
+// interface name (for callers that need it, e.g. cmdCheck's prevResult
+// validation) and a slice of errors (nil when all checks pass) so callers
+// can accumulate and report all failures at once.
+func checkNodeLevelState(vpc, vpcAttachment string) (string, []error) {
+	var errs []error
+
+	if err := vrf.Exists(vpc, vpcAttachment); err != nil {
+		errs = append(errs, fmt.Errorf("vrf %s-%s: %w", vpc, vpcAttachment, err))
+	}
+
+	hostName := intf.GenerateInterfaceNameHost(vpc, vpcAttachment)
+	if _, err := netlink.LinkByName(hostName); err != nil {
+		errs = append(errs, fmt.Errorf("host interface %q: %w", hostName, err))
+	}
+
+	return hostName, errs
+}
+
 // checkGuestInterface verifies that the named interface exists inside the
 // given network namespace. Returns nil when the interface is present.
 func checkGuestInterface(netnsPath, ifName string) error {