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// Copyright 2015 The etcd Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package netutil
import (
"fmt"
"os/exec"
)
// DropPort drops all tcp packets that are received from the given port and sent to the given port.
func DropPort(port int) error {
cmdStr := fmt.Sprintf("sudo iptables -A OUTPUT -p tcp --destination-port %d -j DROP", port)
if _, err := exec.Command("/bin/sh", "-c", cmdStr).Output(); err != nil {
return err
}
cmdStr = fmt.Sprintf("sudo iptables -A INPUT -p tcp --destination-port %d -j DROP", port)
_, err := exec.Command("/bin/sh", "-c", cmdStr).Output()
return err
}
// RecoverPort stops dropping tcp packets at given port.
func RecoverPort(port int) error {
cmdStr := fmt.Sprintf("sudo iptables -D OUTPUT -p tcp --destination-port %d -j DROP", port)
if _, err := exec.Command("/bin/sh", "-c", cmdStr).Output(); err != nil {
return err
}
cmdStr = fmt.Sprintf("sudo iptables -D INPUT -p tcp --destination-port %d -j DROP", port)
_, err := exec.Command("/bin/sh", "-c", cmdStr).Output()
return err
}
// SetLatency adds latency in millisecond scale with random variations.
func SetLatency(ms, rv int) error {
ifces, err := GetDefaultInterfaces()
if err != nil {
return err
}
if rv > ms {
rv = 1
}
for ifce := range ifces {
cmdStr := fmt.Sprintf("sudo tc qdisc add dev %s root netem delay %dms %dms distribution normal", ifce, ms, rv)
_, err = exec.Command("/bin/sh", "-c", cmdStr).Output()
if err != nil {
// the rule has already been added. Overwrite it.
cmdStr = fmt.Sprintf("sudo tc qdisc change dev %s root netem delay %dms %dms distribution normal", ifce, ms, rv)
_, err = exec.Command("/bin/sh", "-c", cmdStr).Output()
if err != nil {
return err
}
}
}
return nil
}
// RemoveLatency resets latency configurations.
func RemoveLatency() error {
ifces, err := GetDefaultInterfaces()
if err != nil {
return err
}
for ifce := range ifces {
_, err = exec.Command("/bin/sh", "-c", fmt.Sprintf("sudo tc qdisc del dev %s root netem", ifce)).Output()
if err != nil {
return err
}
}
return nil
}
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