Add GetNetIndex function to utils

Signed-off-by: Sebastian Sch <[email protected]>

pkg/utils/utils.go

@@ -397,6 +397,38 @@ func GetNetNames(pciAddr string) ([]string, error) {
 	return names, nil
 }
 
+// GetNetIndex returns host net interface index as int for a PCI device from its pci address
+func GetNetIndex(pciAddr string) (int, error) {
+	// get interface name
+	names, err := GetNetNames(pciAddr)
+	if err != nil {
+		return -1, err
+	}
+
+	// check we have exactly one interface name
+	if len(names) != 1 {
+		return -1, nil
+	}
+
+	netDir := filepath.Join(sysBusPci, pciAddr, "net", names[0])
+	if _, err := os.Lstat(netDir); err != nil {
+		return -1, fmt.Errorf("GetNetIndex(): no interface name directory under pci device %s: %q", pciAddr, err)
+	}
+
+	// read the ifindex file from the interface folder
+	indexFile := filepath.Join(netDir, "ifindex")
+	ifIndex, err := os.ReadFile(indexFile)
+	if err != nil {
+		return -1, fmt.Errorf("GetNetIndex(): failed to read ifindex file %s: %q", indexFile, err)
+	}
+
+	intIfIndex, err := strconv.Atoi(strings.TrimSpace(string(ifIndex)))
+	if err != nil {
+		return -1, fmt.Errorf("GetNetIndex(): failed to parse ifindex file content %s: %q", string(ifIndex), err)
+	}
+	return intIfIndex, nil
+}
+
 // GetDriverName returns current driver attached to a pci device from its pci address
 func GetDriverName(pciAddr string) (string, error) {
 	driverLink := filepath.Join(sysBusPci, pciAddr, "driver")

pkg/utils/utils_test.go

@@ -403,6 +403,33 @@ var _ = Describe("In the utils package", func() {
 		),
 	)
 
+	FDescribeTable("getting interface index",
+		func(fs *FakeFilesystem, device string, expected int, shouldFail bool) {
+			defer fs.Use()()
+			actual, err := GetNetIndex(device)
+			Expect(actual).To(Equal(expected))
+			assertShouldFail(err, shouldFail)
+		},
+		Entry("device doesn't exist", &FakeFilesystem{}, "0000:01:10.0", -1, true),
+		Entry("net is not a directory",
+			&FakeFilesystem{
+				Dirs:  []string{"sys/bus/pci/devices/0000:01:10.0"},
+				Files: map[string][]byte{"sys/bus/pci/devices/0000:01:10.0/net": []byte("junk")},
+			},
+			"0000:01:10.0", -1, true,
+		),
+		Entry("ifindex is not a number",
+			&FakeFilesystem{Dirs: []string{"sys/bus/pci/devices/0000:01:10.0/net/fake0"},
+				Files: map[string][]byte{"sys/bus/pci/devices/0000:01:10.0/net/fake0/ifindex": []byte("test")}},
+			"0000:01:10.0", -1, true,
+		),
+		Entry("single network interface",
+			&FakeFilesystem{Dirs: []string{"sys/bus/pci/devices/0000:01:10.0/net/fake0"},
+				Files: map[string][]byte{"sys/bus/pci/devices/0000:01:10.0/net/fake0/ifindex": []byte("72")}},
+			"0000:01:10.0", 72, false,
+		),
+	)
+
 	DescribeTable("getting PF names legacy",
 		func(fs *FakeFilesystem, device string, expected string, shouldFail bool) {
 			fakeNetlinkProvider := mocks.NetlinkProvider{}