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// Copyright 2019 The gVisor 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 iptables
import (
"fmt"
"net"
"os/exec"
"time"
"gvisor.dev/gvisor/runsc/testutil"
)
const iptablesBinary = "iptables"
const localIP = "127.0.0.1"
// filterTable calls `iptables -t filter` with the given args.
func filterTable(args ...string) error {
return tableCmd("filter", args)
}
// natTable calls `iptables -t nat` with the given args.
func natTable(args ...string) error {
return tableCmd("nat", args)
}
func tableCmd(table string, args []string) error {
args = append([]string{"-t", table}, args...)
cmd := exec.Command(iptablesBinary, args...)
if out, err := cmd.CombinedOutput(); err != nil {
return fmt.Errorf("error running iptables with args %v\nerror: %v\noutput: %s", args, err, string(out))
}
return nil
}
// filterTableRules is like filterTable, but runs multiple iptables commands.
func filterTableRules(argsList [][]string) error {
return tableRules("filter", argsList)
}
// natTableRules is like natTable, but runs multiple iptables commands.
func natTableRules(argsList [][]string) error {
return tableRules("nat", argsList)
}
func tableRules(table string, argsList [][]string) error {
for _, args := range argsList {
if err := tableCmd(table, args); err != nil {
return err
}
}
return nil
}
// listenUDP listens on a UDP port and returns the value of net.Conn.Read() for
// the first read on that port.
func listenUDP(port int, timeout time.Duration) error {
localAddr := net.UDPAddr{
Port: port,
}
conn, err := net.ListenUDP(network, &localAddr)
if err != nil {
return err
}
defer conn.Close()
conn.SetDeadline(time.Now().Add(timeout))
_, err = conn.Read([]byte{0})
return err
}
// sendUDPLoop sends 1 byte UDP packets repeatedly to the IP and port specified
// over a duration.
func sendUDPLoop(ip net.IP, port int, duration time.Duration) error {
// Send packets for a few seconds.
remote := net.UDPAddr{
IP: ip,
Port: port,
}
conn, err := net.DialUDP(network, nil, &remote)
if err != nil {
return err
}
defer conn.Close()
to := time.After(duration)
for timedOut := false; !timedOut; {
// This may return an error (connection refused) if the remote
// hasn't started listening yet or they're dropping our
// packets. So we ignore Write errors and depend on the remote
// to report a failure if it doesn't get a packet it needs.
conn.Write([]byte{0})
select {
case <-to:
timedOut = true
default:
time.Sleep(200 * time.Millisecond)
}
}
return nil
}
// listenTCP listens for connections on a TCP port.
func listenTCP(port int, timeout time.Duration) error {
localAddr := net.TCPAddr{
Port: port,
}
// Starts listening on port.
lConn, err := net.ListenTCP("tcp4", &localAddr)
if err != nil {
return err
}
defer lConn.Close()
// Accept connections on port.
lConn.SetDeadline(time.Now().Add(timeout))
conn, err := lConn.AcceptTCP()
if err != nil {
return err
}
conn.Close()
return nil
}
// connectTCP connects to the given IP and port from an ephemeral local address.
func connectTCP(ip net.IP, port int, timeout time.Duration) error {
contAddr := net.TCPAddr{
IP: ip,
Port: port,
}
// The container may not be listening when we first connect, so retry
// upon error.
callback := func() error {
conn, err := net.DialTCP("tcp4", nil, &contAddr)
if conn != nil {
conn.Close()
}
return err
}
if err := testutil.Poll(callback, timeout); err != nil {
return fmt.Errorf("timed out waiting to connect IP, most recent error: %v", err)
}
return nil
}
// localAddrs returns a list of local network interface addresses.
func localAddrs() ([]string, error) {
addrs, err := net.InterfaceAddrs()
if err != nil {
return nil, err
}
addrStrs := make([]string, 0, len(addrs))
for _, addr := range addrs {
addrStrs = append(addrStrs, addr.String())
}
return addrStrs, nil
}
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