Adding --corruption to tools netem set command (#2271)

* adding --corruption to tools netem set command

* added probability

* added test

---------

Co-authored-by: Roman Dodin <dodin.roman@gmail.com>

cmd/tools_netem.go

@@ -26,12 +26,13 @@ import (
 )
 
 var (
-	netemNode      string
-	netemInterface string
-	netemDelay     time.Duration
-	netemJitter    time.Duration
-	netemLoss      float64
-	netemRate      uint64
+	netemNode       string
+	netemInterface  string
+	netemDelay      time.Duration
+	netemJitter     time.Duration
+	netemLoss       float64
+	netemRate       uint64
+	netemCorruption float64
 )
 
 func init() {
@@ -47,6 +48,7 @@ func init() {
 	netemSetCmd.Flags().Float64VarP(&netemLoss, "loss", "", 0,
 		"random packet loss expressed in percentage (e.g. 0.1 means 0.1%)")
 	netemSetCmd.Flags().Uint64VarP(&netemRate, "rate", "", 0, "link rate limit in kbit")
+	netemSetCmd.Flags().Float64VarP(&netemCorruption, "corruption", "", 0, "random packet corruption probability expressed in percentage (e.g. 0.1 means 0.1%)")
 
 	netemSetCmd.MarkFlagRequired("node")
 	netemSetCmd.MarkFlagRequired("interface")
@@ -136,7 +138,7 @@ func netemSetFn(_ *cobra.Command, _ []string) error {
 			return err
 		}
 
-		qdisc, err := tc.SetImpairments(tcnl, netemNode, link, netemDelay, netemJitter, netemLoss, netemRate)
+		qdisc, err := tc.SetImpairments(tcnl, netemNode, link, netemDelay, netemJitter, netemLoss, netemRate, netemCorruption)
 		if err != nil {
 			return err
 		}
@@ -169,6 +171,7 @@ func printImpairments(qdiscs []gotc.Object) {
 		"Jitter",
 		"Packet Loss",
 		"Rate (kbit)",
+		"Corruption",
 	}
 
 	table.SetHeader(header)
@@ -191,7 +194,7 @@ func qdiscToTableData(qdisc gotc.Object) []string {
 		log.Errorf("could not get netlink interface by index: %v", err)
 	}
 
-	var delay, jitter, loss, rate string
+	var delay, jitter, loss, rate, corruption string
 
 	ifDisplayName := link.Attrs().Name
 	if link.Attrs().Alias != "" {
@@ -207,6 +210,7 @@ func qdiscToTableData(qdisc gotc.Object) []string {
 			"N/A", // jitter
 			"N/A", // loss
 			"N/A", // rate
+			"N/A", // corruption
 		}
 	}
 
@@ -220,13 +224,15 @@ func qdiscToTableData(qdisc gotc.Object) []string {
 
 	loss = strconv.FormatFloat(float64(qdisc.Netem.Qopt.Loss)/float64(math.MaxUint32)*100, 'f', 2, 64) + "%"
 	rate = strconv.Itoa(int(qdisc.Netem.Rate.Rate * 8 / 1000))
+	corruption = strconv.FormatFloat(float64(qdisc.Netem.Corrupt.Probability)/float64(math.MaxUint32)*100, 'f', 2, 64) + "%"
 
 	return []string{
 		ifDisplayName,
 		delay,
 		jitter,
 		loss,
 		rate,
+		corruption,
 	}
 }
 

docs/cmd/tools/netem/set.md

@@ -5,6 +5,7 @@ With the `containerlab tools netem set` command users can set link impairments o
 * delay & jitter
 * packet loss
 * rate limiting
+* packet corruption
 
 /// details | Considerations
 Note, that `netem` is a Linux kernel module and it might not be available in particular kernel configurations.
@@ -59,6 +60,12 @@ Packet loss is specified with the `--loss` flag. The loss is specified in percen
 
 Egress rate limiting is specified with the `--rate` flag. The rate is specified in kbit per second format. Example: value `100` means rate of 100kbit/s.
 
+### corruption
+
+Packet corruption percentage is specified with the `--corruption` flag. Corruption modifies the contents of the packet at a random position based on percentage set.
+
+Example: corruption of 10 means 10% corruption probability for a traffic passing the interface.
+
 ## Examples
 
 ### Setting delay and jitter

internal/tc/tc.go

@@ -26,7 +26,7 @@ func NewTC(ns int) (*tc.Tc, error) {
 }
 
 // SetImpairments sets the impairments on the given interface of a node.
-func SetImpairments(tcnl *tc.Tc, nodeName string, link *net.Interface, delay, jitter time.Duration, loss float64, rate uint64) (*tc.Object, error) {
+func SetImpairments(tcnl *tc.Tc, nodeName string, link *net.Interface, delay, jitter time.Duration, loss float64, rate uint64, probability float64) (*tc.Object, error) {
 	err := tcnl.SetOption(netlink.ExtendedAcknowledge, true)
 	if err != nil {
 		return nil, fmt.Errorf("could not set option ExtendedAcknowledge: %v", err)
@@ -59,6 +59,10 @@ func SetImpairments(tcnl *tc.Tc, nodeName string, link *net.Interface, delay, ji
 
 	setRate(&qdisc, rate)
 
+	if probability > 0 {
+		setCorruption(&qdisc, probability)
+	}
+
 	err = tcnl.Qdisc().Replace(&qdisc)
 	if err != nil {
 		return nil, err
@@ -117,6 +121,13 @@ func setRate(qdisc *tc.Object, rate uint64) {
 	}
 }
 
+// setCorruption sets the corruption probability and correlation.
+func setCorruption(qdisc *tc.Object, probability float64) {
+	qdisc.Netem.Corrupt = &tc.NetemCorrupt{
+		Probability: uint32(math.Round(math.MaxUint32 * (probability / float64(100)))),
+	}
+}
+
 // Impairments returns all link impairments of a node.
 func Impairments(tcnl *tc.Tc) ([]tc.Object, error) {
 	qdiscs, err := tcnl.Qdisc().Get()

tests/01-smoke/08-tools-cmds.robot

@@ -28,13 +28,14 @@ Deploy ${lab-name} lab
 
 Add link impairments
     ${rc}    ${output} =    Run And Return Rc And Output
-    ...    sudo -E ${CLAB_BIN} --runtime ${runtime} tools netem set -n clab-${lab-name}-l1 -i eth3 --delay 100ms --jitter 2ms --loss 10 --rate 1000
+    ...    sudo -E ${CLAB_BIN} --runtime ${runtime} tools netem set -n clab-${lab-name}-l1 -i eth3 --delay 100ms --jitter 2ms --loss 10 --rate 1000 --corruption 2
     Log    ${output}
     Should Be Equal As Integers    ${rc}    0
     Should Contain    ${output}    100ms
     Should Contain    ${output}    2ms
     Should Contain    ${output}    10.00%
     Should Contain    ${output}    1000
+    Should Contain    ${output}    2.00%
 
 Show link impairments
     ${rc}    ${output} =    Run And Return Rc And Output