Create Test Case Where Bond MTU is Greater than Links MTU

This commit introduces a new test case in which the bond's MTU is larger than the MTU of its links. The test verifies whether an error is raised when the bond's MTU exceeds the MTU of its links.

- Added an option to modify the MTU setting in the string config used across all tests. This change allows each test to set the MTU option to the desired value.

- Created a constant for the values used in the MTU validation function, thereby improving code readability by avoiding the use of "magic numbers".

Signed-off-by: Alina Sudakov <asudakov@redhat.com>

bond/bond_test.go

@@ -43,14 +43,15 @@ const (
 			"failOverMac": 1,
 			"linksInContainer": %s,
 			"miimon": "100",
-			"mtu": 1400,
+			"mtu": %s,
 			"links": [
 				{"name": "net1"},
 				{"name": "net2"}
 			]
 		}`
 	ActiveBackupMode = "active-backup"
 	BalanceTlbMode   = "balance-tlb"
+	DefaultMTU       = 1400
 )
 
 var Slaves = []string{Slave1, Slave2}
@@ -60,11 +61,6 @@ var _ = Describe("bond plugin", func() {
 	var initNS ns.NetNS
 	var args *skel.CmdArgs
 	var linksInContainer bool
-	var linkAttrs = []netlink.LinkAttrs{
-		{Name: Slave1},
-		{Name: Slave2},
-	}
-
 	AfterEach(func() {
 		Expect(podNS.Close()).To(Succeed())
 		Expect(testutils.UnmountNS(podNS)).To(Succeed())
@@ -74,14 +70,18 @@ var _ = Describe("bond plugin", func() {
 		BeforeEach(func() {
 			var err error
 			linksInContainer = true
+			linkAttrs := []netlink.LinkAttrs{
+				{Name: Slave1},
+				{Name: Slave2},
+			}
 			podNS, err = testutils.NewNS()
 			Expect(err).NotTo(HaveOccurred())
 			addLinksInNS(podNS, linkAttrs)
 			args = &skel.CmdArgs{
 				ContainerID: "dummy",
 				Netns:       podNS.Path(),
 				IfName:      IfName,
-				StdinData:   []byte(fmt.Sprintf(Config, "0.3.1", ActiveBackupMode, strconv.FormatBool(true))),
+				StdinData:   []byte(fmt.Sprintf(Config, "1.0.0", ActiveBackupMode, strconv.FormatBool(linksInContainer), strconv.Itoa(DefaultMTU))),
 			}
 		})
 
@@ -92,26 +92,18 @@ var _ = Describe("bond plugin", func() {
 			})
 			Expect(err).NotTo(HaveOccurred())
 
-			By("validationg the returned result is correct")
+			By("validating the returned result is correct")
 			checkAddReturnResult(&r, IfName)
 
 			err = podNS.Do(func(ns.NetNS) error {
 				defer GinkgoRecover()
 				By("validating the bond interface is configured correctly")
 				link, err := netlink.LinkByName(IfName)
 				Expect(err).NotTo(HaveOccurred())
-				bond := link.(*netlink.Bond)
-				Expect(bond.Attrs().MTU).To(Equal(1400))
-				Expect(bond.Mode.String()).To(Equal(ActiveBackupMode))
-				Expect(bond.Miimon).To(Equal(100))
+				validateBondIFConf(link, DefaultMTU, ActiveBackupMode, 100)
 
 				By("validating the bond slaves are configured correctly")
-				for _, slaveName := range Slaves {
-					slave, err := netlink.LinkByName(slaveName)
-					Expect(err).NotTo(HaveOccurred())
-					Expect(slave.Attrs().Slave).NotTo(BeNil())
-					Expect(slave.Attrs().MasterIndex).To(Equal(bond.Attrs().Index))
-				}
+				validateBondSlavesConf(link, Slaves)
 				return nil
 			})
 			Expect(err).NotTo(HaveOccurred())
@@ -178,7 +170,7 @@ var _ = Describe("bond plugin", func() {
 
 		DescribeTable("verifies the plugin returns correct results for supported tested versions", func(version string) {
 
-			args.StdinData = []byte(fmt.Sprintf(Config, version, ActiveBackupMode, strconv.FormatBool(linksInContainer)))
+			args.StdinData = []byte(fmt.Sprintf(Config, version, ActiveBackupMode, strconv.FormatBool(linksInContainer), strconv.Itoa(DefaultMTU)))
 
 			By(fmt.Sprintf("creating the plugin with config in version %s", version))
 			r, _, err := testutils.CmdAddWithArgs(args, func() error {
@@ -203,7 +195,7 @@ var _ = Describe("bond plugin", func() {
 		)
 
 		It("verifies the plugin copes with duplicated macs in balance-tlb mode", func() {
-			args.StdinData = []byte(fmt.Sprintf(Config, "0.3.1", BalanceTlbMode, strconv.FormatBool(linksInContainer)))
+			args.StdinData = []byte(fmt.Sprintf(Config, "0.3.1", BalanceTlbMode, strconv.FormatBool(linksInContainer), strconv.Itoa(DefaultMTU)))
 
 			err := podNS.Do(func(ns.NetNS) error {
 				defer GinkgoRecover()
@@ -283,10 +275,47 @@ var _ = Describe("bond plugin", func() {
 			Expect(err).NotTo(HaveOccurred())
 		})
 	})
+	When("Links Have Custom MTU", func() {
+		const Slave1Mtu = 1000
+		const Slave2Mtu = 800
+
+		BeforeEach(func() {
+			var err error
+			linksInContainer = true
+			linkAttrs := []netlink.LinkAttrs{
+				{MTU: Slave1Mtu, Name: Slave1},
+				{MTU: Slave2Mtu, Name: Slave2},
+			}
+			podNS, err = testutils.NewNS()
+			Expect(err).NotTo(HaveOccurred())
+			addLinksInNS(podNS, linkAttrs)
+		})
+
+		DescribeTable("Verify plugin raises error when Bond MTU is bigger then links MTU", func(bondMTU string) {
+			args := &skel.CmdArgs{
+				ContainerID: "dummy",
+				Netns:       podNS.Path(),
+				IfName:      IfName,
+				StdinData:   []byte(fmt.Sprintf(Config, "0.3.1", ActiveBackupMode, strconv.FormatBool(linksInContainer), bondMTU)),
+			}
+			By("creating the plugin")
+			_, _, err := testutils.CmdAddWithArgs(args, func() error {
+				return cmdAdd(args)
+			})
+			Expect(err).To(HaveOccurred())
+		},
+			Entry("Bond MTU is bigger then one of links MTU", "1200"),
+			Entry("Bond MTU is bigger then all of links MTU", "900"),
+		)
+	})
 	When("links are in the initial network namespace at initial state (meaning linksInContainer is false)", func() {
 		BeforeEach(func() {
 			var err error
 			linksInContainer = false
+			linkAttrs := []netlink.LinkAttrs{
+				{Name: Slave1},
+				{Name: Slave2},
+			}
 			podNS, err = testutils.NewNS()
 			Expect(err).NotTo(HaveOccurred())
 			initNS, err = testutils.NewNS()
@@ -303,7 +332,7 @@ var _ = Describe("bond plugin", func() {
 				ContainerID: "dummy",
 				Netns:       podNS.Path(),
 				IfName:      IfName,
-				StdinData:   []byte(fmt.Sprintf(Config, "0.3.1", ActiveBackupMode, strconv.FormatBool(linksInContainer))),
+				StdinData:   []byte(fmt.Sprintf(Config, "0.3.1", ActiveBackupMode, strconv.FormatBool(linksInContainer), strconv.Itoa(DefaultMTU))),
 			}
 			err := initNS.Do(func(ns.NetNS) error {
 				defer GinkgoRecover()
@@ -324,7 +353,7 @@ var _ = Describe("bond plugin", func() {
 				By("validating the bond interface is configured correctly")
 				link, err := netlink.LinkByName(IfName)
 				Expect(err).NotTo(HaveOccurred())
-				validateBondIFConf(link, 1400, ActiveBackupMode, 100)
+				validateBondIFConf(link, DefaultMTU, ActiveBackupMode, 100)
 
 				By("validating the bond slaves are configured correctly")
 				validateBondSlavesConf(link, Slaves)

bond/util/validation.go

@@ -7,13 +7,19 @@ import (
 	"github.com/vishvananda/netlink"
 )
 
+const (
+	standardEthernetMTU = 1500
+	defaultMTU          = standardEthernetMTU
+	minMtuIpv4Packet    = 68
+)
+
 func ValidateMTU(slaveLinks []netlink.Link, mtu int) error {
 	// if not specified set MTU to default
 	if mtu == 0 {
-		mtu = 1500
+		mtu = defaultMTU
 	}
 
-	if mtu < 68 {
+	if mtu < minMtuIpv4Packet {
 		return fmt.Errorf("Invalid bond MTU value (%+v), should be 68 or bigger", mtu)
 	}
 	netHandle, err := netlink.NewHandle()