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138 lines
3.9 KiB
138 lines
3.9 KiB
/*
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Copyright 2020 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 net
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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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)
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// IPFamily refers to a specific family if not empty, i.e. "4" or "6".
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type IPFamily string
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// Constants for valid IPFamilys:
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const (
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IPv4 IPFamily = "4"
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IPv6 = "6"
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)
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// Protocol is a network protocol support by LocalPort.
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type Protocol string
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// Constants for valid protocols:
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const (
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TCP Protocol = "TCP"
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UDP Protocol = "UDP"
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)
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// LocalPort represents an IP address and port pair along with a protocol
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// and potentially a specific IP family.
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// A LocalPort can be opened and subsequently closed.
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type LocalPort struct {
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// Description is an arbitrary string.
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Description string
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// IP is the IP address part of a given local port.
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// If this string is empty, the port binds to all local IP addresses.
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IP string
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// If IPFamily is not empty, the port binds only to addresses of this
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// family.
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// IF empty along with IP, bind to local addresses of any family.
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IPFamily IPFamily
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// Port is the port number.
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// A value of 0 causes a port to be automatically chosen.
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Port int
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// Protocol is the protocol, e.g. TCP
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Protocol Protocol
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}
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// NewLocalPort returns a LocalPort instance and ensures IPFamily and IP are
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// consistent and that the given protocol is valid.
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func NewLocalPort(desc, ip string, ipFamily IPFamily, port int, protocol Protocol) (*LocalPort, error) {
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if protocol != TCP && protocol != UDP {
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return nil, fmt.Errorf("Unsupported protocol %s", protocol)
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}
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if ipFamily != "" && ipFamily != "4" && ipFamily != "6" {
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return nil, fmt.Errorf("Invalid IP family %s", ipFamily)
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}
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if ip != "" {
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parsedIP := net.ParseIP(ip)
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if parsedIP == nil {
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return nil, fmt.Errorf("invalid ip address %s", ip)
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}
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asIPv4 := parsedIP.To4()
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if asIPv4 == nil && ipFamily == IPv4 || asIPv4 != nil && ipFamily == IPv6 {
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return nil, fmt.Errorf("ip address and family mismatch %s, %s", ip, ipFamily)
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}
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}
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return &LocalPort{Description: desc, IP: ip, IPFamily: ipFamily, Port: port, Protocol: protocol}, nil
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}
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func (lp *LocalPort) String() string {
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ipPort := net.JoinHostPort(lp.IP, strconv.Itoa(lp.Port))
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return fmt.Sprintf("%q (%s/%s%s)", lp.Description, ipPort, strings.ToLower(string(lp.Protocol)), lp.IPFamily)
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}
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// Closeable closes an opened LocalPort.
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type Closeable interface {
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Close() error
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}
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// PortOpener can open a LocalPort and allows later closing it.
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type PortOpener interface {
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OpenLocalPort(lp *LocalPort) (Closeable, error)
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}
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type listenPortOpener struct{}
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// ListenPortOpener opens ports by calling bind() and listen().
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var ListenPortOpener listenPortOpener
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// OpenLocalPort holds the given local port open.
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func (l *listenPortOpener) OpenLocalPort(lp *LocalPort) (Closeable, error) {
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return openLocalPort(lp)
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}
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func openLocalPort(lp *LocalPort) (Closeable, error) {
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var socket Closeable
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hostPort := net.JoinHostPort(lp.IP, strconv.Itoa(lp.Port))
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switch lp.Protocol {
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case TCP:
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network := "tcp" + string(lp.IPFamily)
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listener, err := net.Listen(network, hostPort)
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if err != nil {
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return nil, err
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}
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socket = listener
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case UDP:
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network := "udp" + string(lp.IPFamily)
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addr, err := net.ResolveUDPAddr(network, hostPort)
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if err != nil {
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return nil, err
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}
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conn, err := net.ListenUDP(network, addr)
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if err != nil {
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return nil, err
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}
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socket = conn
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default:
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return nil, fmt.Errorf("unknown protocol %q", lp.Protocol)
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}
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return socket, nil
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}
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