105 lines
4.2 KiB
Go
105 lines
4.2 KiB
Go
/*
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Copyright 2016 The Kubernetes Authors.
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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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http://www.apache.org/licenses/LICENSE-2.0
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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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*/
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package util
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import (
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"fmt"
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"net"
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"strconv"
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"strings"
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"k8s.io/utils/exec"
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)
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// Utilities for dealing with conntrack
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const noConnectionToDelete = "0 flow entries have been deleted"
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func IsIPv6(netIP net.IP) bool {
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return netIP != nil && netIP.To4() == nil
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}
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func IsIPv6String(ip string) bool {
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netIP := net.ParseIP(ip)
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return IsIPv6(netIP)
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}
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func parametersWithFamily(isIPv6 bool, parameters ...string) []string {
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if isIPv6 {
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parameters = append(parameters, "-f", "ipv6")
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}
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return parameters
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}
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// ClearUDPConntrackForIP uses the conntrack tool to delete the conntrack entries
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// for the UDP connections specified by the given service IP
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func ClearUDPConntrackForIP(execer exec.Interface, ip string) error {
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parameters := parametersWithFamily(IsIPv6String(ip), "-D", "--orig-dst", ip, "-p", "udp")
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err := ExecConntrackTool(execer, parameters...)
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if err != nil && !strings.Contains(err.Error(), noConnectionToDelete) {
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// TODO: Better handling for deletion failure. When failure occur, stale udp connection may not get flushed.
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// These stale udp connection will keep black hole traffic. Making this a best effort operation for now, since it
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// is expensive to baby-sit all udp connections to kubernetes services.
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return fmt.Errorf("error deleting connection tracking state for UDP service IP: %s, error: %v", ip, err)
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}
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return nil
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}
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// ExecConntrackTool executes the conntrack tool using the given parameters
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func ExecConntrackTool(execer exec.Interface, parameters ...string) error {
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conntrackPath, err := execer.LookPath("conntrack")
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if err != nil {
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return fmt.Errorf("error looking for path of conntrack: %v", err)
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}
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output, err := execer.Command(conntrackPath, parameters...).CombinedOutput()
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if err != nil {
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return fmt.Errorf("conntrack command returned: %q, error message: %s", string(output), err)
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}
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return nil
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}
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// ClearUDPConntrackForPort uses the conntrack tool to delete the conntrack entries
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// for the UDP connections specified by the port.
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// When a packet arrives, it will not go through NAT table again, because it is not "the first" packet.
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// The solution is clearing the conntrack. Known issues:
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// https://github.com/docker/docker/issues/8795
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// https://github.com/kubernetes/kubernetes/issues/31983
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func ClearUDPConntrackForPort(execer exec.Interface, port int, isIPv6 bool) error {
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if port <= 0 {
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return fmt.Errorf("Wrong port number. The port number must be greater than zero")
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}
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parameters := parametersWithFamily(isIPv6, "-D", "-p", "udp", "--dport", strconv.Itoa(port))
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err := ExecConntrackTool(execer, parameters...)
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if err != nil && !strings.Contains(err.Error(), noConnectionToDelete) {
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return fmt.Errorf("error deleting conntrack entries for UDP port: %d, error: %v", port, err)
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}
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return nil
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}
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// ClearUDPConntrackForPeers uses the conntrack tool to delete the conntrack entries
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// for the UDP connections specified by the {origin, dest} IP pair.
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func ClearUDPConntrackForPeers(execer exec.Interface, origin, dest string) error {
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parameters := parametersWithFamily(IsIPv6String(origin), "-D", "--orig-dst", origin, "--dst-nat", dest, "-p", "udp")
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err := ExecConntrackTool(execer, parameters...)
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if err != nil && !strings.Contains(err.Error(), noConnectionToDelete) {
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// TODO: Better handling for deletion failure. When failure occur, stale udp connection may not get flushed.
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// These stale udp connection will keep black hole traffic. Making this a best effort operation for now, since it
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// is expensive to baby sit all udp connections to kubernetes services.
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return fmt.Errorf("error deleting conntrack entries for UDP peer {%s, %s}, error: %v", origin, dest, err)
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}
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return nil
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}
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