290 lines
7.2 KiB
Go
290 lines
7.2 KiB
Go
// Copyright 2019 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package iptables
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import (
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"encoding/binary"
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"errors"
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"fmt"
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"net"
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"os/exec"
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"strings"
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"time"
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"gvisor.dev/gvisor/pkg/test/testutil"
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)
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// filterTable calls `ip{6}tables -t filter` with the given args.
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func filterTable(ipv6 bool, args ...string) error {
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return tableCmd(ipv6, "filter", args)
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}
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// natTable calls `ip{6}tables -t nat` with the given args.
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func natTable(ipv6 bool, args ...string) error {
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return tableCmd(ipv6, "nat", args)
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}
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func tableCmd(ipv6 bool, table string, args []string) error {
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args = append([]string{"-t", table}, args...)
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binary := "iptables"
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if ipv6 {
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binary = "ip6tables"
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}
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cmd := exec.Command(binary, args...)
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if out, err := cmd.CombinedOutput(); err != nil {
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return fmt.Errorf("error running iptables with args %v\nerror: %v\noutput: %s", args, err, string(out))
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}
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return nil
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}
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// filterTableRules is like filterTable, but runs multiple iptables commands.
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func filterTableRules(ipv6 bool, argsList [][]string) error {
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return tableRules(ipv6, "filter", argsList)
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}
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// natTableRules is like natTable, but runs multiple iptables commands.
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func natTableRules(ipv6 bool, argsList [][]string) error {
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return tableRules(ipv6, "nat", argsList)
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}
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func tableRules(ipv6 bool, table string, argsList [][]string) error {
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for _, args := range argsList {
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if err := tableCmd(ipv6, table, args); err != nil {
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return err
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}
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}
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return nil
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}
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// listenUDP listens on a UDP port and returns the value of net.Conn.Read() for
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// the first read on that port.
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func listenUDP(port int, timeout time.Duration) error {
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localAddr := net.UDPAddr{
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Port: port,
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}
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conn, err := net.ListenUDP("udp", &localAddr)
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if err != nil {
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return err
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}
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defer conn.Close()
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conn.SetDeadline(time.Now().Add(timeout))
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_, err = conn.Read([]byte{0})
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return err
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}
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// sendUDPLoop sends 1 byte UDP packets repeatedly to the IP and port specified
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// over a duration.
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func sendUDPLoop(ip net.IP, port int, duration time.Duration) error {
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conn, err := connectUDP(ip, port)
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if err != nil {
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return err
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}
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defer conn.Close()
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loopUDP(conn, duration)
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return nil
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}
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// spawnUDPLoop works like sendUDPLoop, but returns immediately and sends
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// packets in another goroutine.
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func spawnUDPLoop(ip net.IP, port int, duration time.Duration) error {
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conn, err := connectUDP(ip, port)
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if err != nil {
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return err
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}
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go func() {
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defer conn.Close()
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loopUDP(conn, duration)
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}()
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return nil
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}
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func connectUDP(ip net.IP, port int) (net.Conn, error) {
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remote := net.UDPAddr{
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IP: ip,
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Port: port,
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}
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conn, err := net.DialUDP("udp", nil, &remote)
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if err != nil {
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return nil, err
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}
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return conn, nil
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}
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func loopUDP(conn net.Conn, duration time.Duration) {
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to := time.After(duration)
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for timedOut := false; !timedOut; {
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// This may return an error (connection refused) if the remote
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// hasn't started listening yet or they're dropping our
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// packets. So we ignore Write errors and depend on the remote
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// to report a failure if it doesn't get a packet it needs.
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conn.Write([]byte{0})
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select {
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case <-to:
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timedOut = true
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default:
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time.Sleep(200 * time.Millisecond)
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}
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}
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}
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// listenTCP listens for connections on a TCP port.
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func listenTCP(port int, timeout time.Duration) error {
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localAddr := net.TCPAddr{
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Port: port,
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}
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// Starts listening on port.
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lConn, err := net.ListenTCP("tcp", &localAddr)
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if err != nil {
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return err
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}
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defer lConn.Close()
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// Accept connections on port.
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lConn.SetDeadline(time.Now().Add(timeout))
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conn, err := lConn.AcceptTCP()
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if err != nil {
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return err
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}
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conn.Close()
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return nil
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}
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// connectTCP connects to the given IP and port from an ephemeral local address.
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func connectTCP(ip net.IP, port int, timeout time.Duration) error {
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contAddr := net.TCPAddr{
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IP: ip,
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Port: port,
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}
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// The container may not be listening when we first connect, so retry
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// upon error.
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callback := func() error {
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conn, err := net.DialTimeout("tcp", contAddr.String(), timeout)
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if conn != nil {
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conn.Close()
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}
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return err
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}
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if err := testutil.Poll(callback, timeout); err != nil {
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return fmt.Errorf("timed out waiting to connect IP on port %v, most recent error: %v", port, err)
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}
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return nil
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}
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// localAddrs returns a list of local network interface addresses. When ipv6 is
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// true, only IPv6 addresses are returned. Otherwise only IPv4 addresses are
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// returned.
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func localAddrs(ipv6 bool) ([]string, error) {
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addrs, err := net.InterfaceAddrs()
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if err != nil {
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return nil, err
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}
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addrStrs := make([]string, 0, len(addrs))
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for _, addr := range addrs {
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// Add only IPv4 or only IPv6 addresses.
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parts := strings.Split(addr.String(), "/")
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if len(parts) != 2 {
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return nil, fmt.Errorf("bad interface address: %q", addr.String())
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}
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if isIPv6 := net.ParseIP(parts[0]).To4() == nil; isIPv6 == ipv6 {
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addrStrs = append(addrStrs, addr.String())
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}
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}
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return filterAddrs(addrStrs, ipv6), nil
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}
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func filterAddrs(addrs []string, ipv6 bool) []string {
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addrStrs := make([]string, 0, len(addrs))
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for _, addr := range addrs {
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// Add only IPv4 or only IPv6 addresses.
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parts := strings.Split(addr, "/")
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if isIPv6 := net.ParseIP(parts[0]).To4() == nil; isIPv6 == ipv6 {
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addrStrs = append(addrStrs, parts[0])
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}
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}
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return addrStrs
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}
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// getInterfaceName returns the name of the interface other than loopback.
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func getInterfaceName() (string, bool) {
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iface, ok := getNonLoopbackInterface()
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if !ok {
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return "", false
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}
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return iface.Name, true
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}
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func getInterfaceAddrs(ipv6 bool) ([]net.IP, error) {
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iface, ok := getNonLoopbackInterface()
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if !ok {
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return nil, errors.New("no non-loopback interface found")
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}
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addrs, err := iface.Addrs()
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if err != nil {
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return nil, err
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}
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// Get only IPv4 or IPv6 addresses.
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ips := make([]net.IP, 0, len(addrs))
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for _, addr := range addrs {
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parts := strings.Split(addr.String(), "/")
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var ip net.IP
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// To16() returns IPv4 addresses as IPv4-mapped IPv6 addresses.
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// So we check whether To4() returns nil to test whether the
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// address is v4 or v6.
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if v4 := net.ParseIP(parts[0]).To4(); ipv6 && v4 == nil {
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ip = net.ParseIP(parts[0]).To16()
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} else {
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ip = v4
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}
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if ip != nil {
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ips = append(ips, ip)
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}
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}
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return ips, nil
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}
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func getNonLoopbackInterface() (net.Interface, bool) {
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if interfaces, err := net.Interfaces(); err == nil {
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for _, intf := range interfaces {
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if intf.Name != "lo" {
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return intf, true
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}
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}
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}
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return net.Interface{}, false
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}
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func htons(x uint16) uint16 {
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buf := make([]byte, 2)
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binary.BigEndian.PutUint16(buf, x)
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return binary.LittleEndian.Uint16(buf)
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}
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func localIP(ipv6 bool) string {
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if ipv6 {
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return "::1"
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}
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return "127.0.0.1"
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}
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func nowhereIP(ipv6 bool) string {
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if ipv6 {
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return "2001:db8::1"
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}
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return "192.0.2.1"
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}
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