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483 lines
14 KiB
Go
483 lines
14 KiB
Go
// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// netstack doesn't build on 32-bit machines (https://github.com/google/gvisor/issues/5241)
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// +build amd64 arm64 ppc64le riscv64 s390x
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// Package netstack wires up gVisor's netstack into Tailscale.
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package netstack
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import (
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"context"
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"errors"
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"fmt"
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"io"
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"log"
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"net"
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"strconv"
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"strings"
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"sync"
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"time"
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"gvisor.dev/gvisor/pkg/tcpip"
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"gvisor.dev/gvisor/pkg/tcpip/adapters/gonet"
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"gvisor.dev/gvisor/pkg/tcpip/buffer"
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"gvisor.dev/gvisor/pkg/tcpip/header"
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"gvisor.dev/gvisor/pkg/tcpip/link/channel"
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"gvisor.dev/gvisor/pkg/tcpip/network/ipv4"
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"gvisor.dev/gvisor/pkg/tcpip/network/ipv6"
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"gvisor.dev/gvisor/pkg/tcpip/stack"
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"gvisor.dev/gvisor/pkg/tcpip/transport/icmp"
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"gvisor.dev/gvisor/pkg/tcpip/transport/tcp"
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"gvisor.dev/gvisor/pkg/tcpip/transport/udp"
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"gvisor.dev/gvisor/pkg/waiter"
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"inet.af/netaddr"
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"tailscale.com/net/packet"
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"tailscale.com/types/logger"
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"tailscale.com/types/netmap"
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"tailscale.com/util/dnsname"
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"tailscale.com/wgengine"
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"tailscale.com/wgengine/filter"
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"tailscale.com/wgengine/magicsock"
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"tailscale.com/wgengine/tstun"
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)
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const debugNetstack = false
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// Impl contains the state for the netstack implementation,
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// and implements wgengine.FakeImpl to act as a userspace network
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// stack when Tailscale is running in fake mode.
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type Impl struct {
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ipstack *stack.Stack
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linkEP *channel.Endpoint
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tundev *tstun.TUN
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e wgengine.Engine
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mc *magicsock.Conn
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logf logger.Logf
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mu sync.Mutex
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dns DNSMap
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}
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const nicID = 1
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const mtu = 1500
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// Create creates and populates a new Impl.
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func Create(logf logger.Logf, tundev *tstun.TUN, e wgengine.Engine, mc *magicsock.Conn) (*Impl, error) {
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if mc == nil {
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return nil, errors.New("nil magicsock.Conn")
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}
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if tundev == nil {
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return nil, errors.New("nil tundev")
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}
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if logf == nil {
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return nil, errors.New("nil logger")
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}
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if e == nil {
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return nil, errors.New("nil Engine")
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}
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ipstack := stack.New(stack.Options{
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NetworkProtocols: []stack.NetworkProtocolFactory{ipv4.NewProtocol, ipv6.NewProtocol},
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TransportProtocols: []stack.TransportProtocolFactory{tcp.NewProtocol, udp.NewProtocol, icmp.NewProtocol4, icmp.NewProtocol6},
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})
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linkEP := channel.New(512, mtu, "")
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if tcpipProblem := ipstack.CreateNIC(nicID, linkEP); tcpipProblem != nil {
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return nil, fmt.Errorf("could not create netstack NIC: %v", tcpipProblem)
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}
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// Add IPv4 and IPv6 default routes, so all incoming packets from the Tailscale side
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// are handled by the one fake NIC we use.
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ipv4Subnet, _ := tcpip.NewSubnet(tcpip.Address(strings.Repeat("\x00", 4)), tcpip.AddressMask(strings.Repeat("\x00", 4)))
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ipv6Subnet, _ := tcpip.NewSubnet(tcpip.Address(strings.Repeat("\x00", 16)), tcpip.AddressMask(strings.Repeat("\x00", 16)))
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ipstack.SetRouteTable([]tcpip.Route{
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{
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Destination: ipv4Subnet,
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NIC: nicID,
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},
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{
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Destination: ipv6Subnet,
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NIC: nicID,
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},
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})
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ns := &Impl{
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logf: logf,
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ipstack: ipstack,
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linkEP: linkEP,
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tundev: tundev,
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e: e,
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mc: mc,
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}
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return ns, nil
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}
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// Start sets up all the handlers so netstack can start working. Implements
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// wgengine.FakeImpl.
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func (ns *Impl) Start() error {
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ns.e.AddNetworkMapCallback(ns.updateIPs)
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// size = 0 means use default buffer size
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const tcpReceiveBufferSize = 0
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const maxInFlightConnectionAttempts = 16
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tcpFwd := tcp.NewForwarder(ns.ipstack, tcpReceiveBufferSize, maxInFlightConnectionAttempts, ns.acceptTCP)
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udpFwd := udp.NewForwarder(ns.ipstack, ns.acceptUDP)
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ns.ipstack.SetTransportProtocolHandler(tcp.ProtocolNumber, tcpFwd.HandlePacket)
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ns.ipstack.SetTransportProtocolHandler(udp.ProtocolNumber, udpFwd.HandlePacket)
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go ns.injectOutbound()
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ns.tundev.PostFilterIn = ns.injectInbound
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return nil
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}
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// DNSMap maps MagicDNS names (both base + FQDN) to their first IP.
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// It should not be mutated once created.
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type DNSMap map[string]netaddr.IP
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func DNSMapFromNetworkMap(nm *netmap.NetworkMap) DNSMap {
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ret := make(DNSMap)
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suffix := nm.MagicDNSSuffix()
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if nm.Name != "" && len(nm.Addresses) > 0 {
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ip := nm.Addresses[0].IP
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ret[strings.TrimRight(nm.Name, ".")] = ip
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if dnsname.HasSuffix(nm.Name, suffix) {
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ret[dnsname.TrimSuffix(nm.Name, suffix)] = ip
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}
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}
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for _, p := range nm.Peers {
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if p.Name != "" && len(p.Addresses) > 0 {
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ip := p.Addresses[0].IP
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ret[strings.TrimRight(p.Name, ".")] = ip
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if dnsname.HasSuffix(p.Name, suffix) {
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ret[dnsname.TrimSuffix(p.Name, suffix)] = ip
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}
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}
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}
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return ret
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}
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func (ns *Impl) updateDNS(nm *netmap.NetworkMap) {
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ns.mu.Lock()
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defer ns.mu.Unlock()
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ns.dns = DNSMapFromNetworkMap(nm)
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}
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func (ns *Impl) updateIPs(nm *netmap.NetworkMap) {
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ns.updateDNS(nm)
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oldIPs := make(map[tcpip.Address]bool)
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for _, ip := range ns.ipstack.AllAddresses()[nicID] {
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oldIPs[ip.AddressWithPrefix.Address] = true
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}
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newIPs := make(map[tcpip.Address]bool)
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for _, ip := range nm.Addresses {
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newIPs[tcpip.Address(ip.IP.IPAddr().IP)] = true
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}
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ipsToBeAdded := make(map[tcpip.Address]bool)
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for ip := range newIPs {
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if !oldIPs[ip] {
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ipsToBeAdded[ip] = true
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}
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}
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ipsToBeRemoved := make(map[tcpip.Address]bool)
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for ip := range oldIPs {
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if !newIPs[ip] {
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ipsToBeRemoved[ip] = true
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}
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}
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for ip := range ipsToBeRemoved {
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err := ns.ipstack.RemoveAddress(nicID, ip)
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if err != nil {
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ns.logf("netstack: could not deregister IP %s: %v", ip, err)
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} else {
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ns.logf("[v2] netstack: deregistered IP %s", ip)
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}
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}
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for ip := range ipsToBeAdded {
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var err *tcpip.Error
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if ip.To4() == "" {
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err = ns.ipstack.AddAddress(nicID, ipv6.ProtocolNumber, ip)
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} else {
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err = ns.ipstack.AddAddress(nicID, ipv4.ProtocolNumber, ip)
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}
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if err != nil {
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ns.logf("netstack: could not register IP %s: %v", ip, err)
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} else {
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ns.logf("[v2] netstack: registered IP %s", ip)
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}
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}
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}
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// Resolve resolves addr into an IP:port using first the MagicDNS contents
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// of m, else using the system resolver.
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func (m DNSMap) Resolve(ctx context.Context, addr string) (netaddr.IPPort, error) {
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ipp, pippErr := netaddr.ParseIPPort(addr)
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if pippErr == nil {
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return ipp, nil
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}
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host, port, err := net.SplitHostPort(addr)
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if err != nil {
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// addr is malformed.
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return netaddr.IPPort{}, err
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}
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if net.ParseIP(host) != nil {
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// The host part of addr was an IP, so the netaddr.ParseIPPort above should've
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// passed. Must've been a bad port number. Return the original error.
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return netaddr.IPPort{}, pippErr
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}
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port16, err := strconv.ParseUint(port, 10, 16)
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if err != nil {
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return netaddr.IPPort{}, fmt.Errorf("invalid port in address %q", addr)
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}
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// Host is not an IP, so assume it's a DNS name.
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// Try MagicDNS first, else otherwise a real DNS lookup.
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ip := m[host]
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if !ip.IsZero() {
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return netaddr.IPPort{IP: ip, Port: uint16(port16)}, nil
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}
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// No Magic DNS name so try real DNS.
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var r net.Resolver
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ips, err := r.LookupIP(ctx, "ip", host)
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if err != nil {
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return netaddr.IPPort{}, err
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}
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if len(ips) == 0 {
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return netaddr.IPPort{}, fmt.Errorf("DNS lookup returned no results for %q", host)
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}
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ip, _ = netaddr.FromStdIP(ips[0])
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return netaddr.IPPort{IP: ip, Port: uint16(port16)}, nil
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}
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func (ns *Impl) DialContextTCP(ctx context.Context, addr string) (*gonet.TCPConn, error) {
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ns.mu.Lock()
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dnsMap := ns.dns
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ns.mu.Unlock()
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remoteIPPort, err := dnsMap.Resolve(ctx, addr)
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if err != nil {
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return nil, err
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}
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remoteAddress := tcpip.FullAddress{
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NIC: nicID,
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Addr: tcpip.Address(remoteIPPort.IP.IPAddr().IP),
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Port: remoteIPPort.Port,
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}
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var ipType tcpip.NetworkProtocolNumber
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if remoteIPPort.IP.Is4() {
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ipType = ipv4.ProtocolNumber
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} else {
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ipType = ipv6.ProtocolNumber
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}
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return gonet.DialContextTCP(ctx, ns.ipstack, remoteAddress, ipType)
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}
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func (ns *Impl) injectOutbound() {
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for {
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packetInfo, ok := ns.linkEP.ReadContext(context.Background())
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if !ok {
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ns.logf("[v2] ReadContext-for-write = ok=false")
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continue
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}
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pkt := packetInfo.Pkt
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hdrNetwork := pkt.NetworkHeader()
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hdrTransport := pkt.TransportHeader()
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full := make([]byte, 0, pkt.Size())
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full = append(full, hdrNetwork.View()...)
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full = append(full, hdrTransport.View()...)
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full = append(full, pkt.Data.ToView()...)
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if debugNetstack {
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ns.logf("[v2] packet Write out: % x", full)
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}
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if err := ns.tundev.InjectOutbound(full); err != nil {
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log.Printf("netstack inject outbound: %v", err)
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return
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}
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}
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}
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func (ns *Impl) injectInbound(p *packet.Parsed, t *tstun.TUN) filter.Response {
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var pn tcpip.NetworkProtocolNumber
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switch p.IPVersion {
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case 4:
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pn = header.IPv4ProtocolNumber
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case 6:
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pn = header.IPv6ProtocolNumber
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}
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if debugNetstack {
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ns.logf("[v2] packet in (from %v): % x", p.Src, p.Buffer())
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}
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vv := buffer.View(append([]byte(nil), p.Buffer()...)).ToVectorisedView()
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packetBuf := stack.NewPacketBuffer(stack.PacketBufferOptions{
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Data: vv,
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})
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ns.linkEP.InjectInbound(pn, packetBuf)
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return filter.Accept
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}
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func (ns *Impl) acceptTCP(r *tcp.ForwarderRequest) {
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if debugNetstack {
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// Kinda ugly:
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// ForwarderRequest: &{{{{0 0}}} 0xc0001c30b0 0xc0004c3d40 {1240 6 true 826109390 0 true}
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ns.logf("[v2] ForwarderRequest: %v", r)
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}
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var wq waiter.Queue
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ep, err := r.CreateEndpoint(&wq)
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if err != nil {
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r.Complete(true)
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return
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}
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localAddr, err := ep.GetLocalAddress()
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if err != nil {
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r.Complete(true)
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return
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}
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r.Complete(false)
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c := gonet.NewTCPConn(&wq, ep)
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go ns.forwardTCP(c, &wq, localAddr.Port)
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}
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func (ns *Impl) forwardTCP(client *gonet.TCPConn, wq *waiter.Queue, port uint16) {
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defer client.Close()
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ns.logf("[v2] netstack: forwarding incoming connection on port %v", port)
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ctx, cancel := context.WithCancel(context.Background())
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defer cancel()
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waitEntry, notifyCh := waiter.NewChannelEntry(nil)
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wq.EventRegister(&waitEntry, waiter.EventHUp)
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defer wq.EventUnregister(&waitEntry)
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done := make(chan bool)
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// netstack doesn't close the notification channel automatically if there was no
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// hup signal, so we close done after we're done to not leak the goroutine below.
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defer close(done)
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go func() {
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select {
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case <-notifyCh:
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case <-done:
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}
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cancel()
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}()
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var stdDialer net.Dialer
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server, err := stdDialer.DialContext(ctx, "tcp", net.JoinHostPort("localhost", strconv.Itoa(int(port))))
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if err != nil {
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ns.logf("netstack: could not connect to local server on port %v: %v", port, err)
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return
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}
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defer server.Close()
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backendLocalAddr := server.LocalAddr().(*net.TCPAddr)
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backendLocalIPPort, _ := netaddr.FromStdAddr(backendLocalAddr.IP, backendLocalAddr.Port, backendLocalAddr.Zone)
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clientRemoteIP, _ := netaddr.FromStdIP(client.RemoteAddr().(*net.TCPAddr).IP)
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ns.e.RegisterIPPortIdentity(backendLocalIPPort, clientRemoteIP)
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defer ns.e.UnregisterIPPortIdentity(backendLocalIPPort)
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connClosed := make(chan error, 2)
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go func() {
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_, err := io.Copy(server, client)
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connClosed <- err
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}()
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go func() {
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_, err := io.Copy(client, server)
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connClosed <- err
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}()
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err = <-connClosed
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if err != nil {
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ns.logf("proxy connection closed with error: %v", err)
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}
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ns.logf("[v2] netstack: forwarder connection on port %v closed", port)
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}
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func (ns *Impl) acceptUDP(r *udp.ForwarderRequest) {
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ns.logf("[v2] UDP ForwarderRequest: %v", r)
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var wq waiter.Queue
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ep, err := r.CreateEndpoint(&wq)
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if err != nil {
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ns.logf("Could not create endpoint, exiting")
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return
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}
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localAddr, err := ep.GetLocalAddress()
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if err != nil {
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return
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}
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remoteAddr, err := ep.GetRemoteAddress()
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if err != nil {
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return
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}
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c := gonet.NewUDPConn(ns.ipstack, &wq, ep)
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go ns.forwardUDP(c, &wq, localAddr, remoteAddr)
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}
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func (ns *Impl) forwardUDP(client *gonet.UDPConn, wq *waiter.Queue, clientLocalAddr, clientRemoteAddr tcpip.FullAddress) {
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port := clientLocalAddr.Port
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ns.logf("[v2] netstack: forwarding incoming UDP connection on port %v", port)
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backendListenAddr := &net.UDPAddr{IP: net.ParseIP("127.0.0.1"), Port: int(clientRemoteAddr.Port)}
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backendRemoteAddr := &net.UDPAddr{IP: net.ParseIP("127.0.0.1"), Port: int(port)}
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backendConn, err := net.ListenUDP("udp4", backendListenAddr)
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if err != nil {
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ns.logf("netstack: could not bind local port %v: %v, trying again with random port", clientRemoteAddr.Port, err)
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backendListenAddr.Port = 0
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backendConn, err = net.ListenUDP("udp4", backendListenAddr)
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if err != nil {
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ns.logf("netstack: could not connect to local UDP server on port %v: %v", port, err)
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return
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}
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}
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backendLocalAddr := backendConn.LocalAddr().(*net.UDPAddr)
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backendLocalIPPort, ok := netaddr.FromStdAddr(backendListenAddr.IP, backendLocalAddr.Port, backendLocalAddr.Zone)
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if !ok {
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ns.logf("could not get backend local IP:port from %v:%v", backendLocalAddr.IP, backendLocalAddr.Port)
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}
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clientRemoteIP, _ := netaddr.FromStdIP(net.ParseIP(clientRemoteAddr.Addr.String()))
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ns.e.RegisterIPPortIdentity(backendLocalIPPort, clientRemoteIP)
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ctx, cancel := context.WithCancel(context.Background())
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timer := time.AfterFunc(2*time.Minute, func() {
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ns.e.UnregisterIPPortIdentity(backendLocalIPPort)
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ns.logf("netstack: UDP session between %s and %s timed out", clientRemoteAddr, backendRemoteAddr)
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cancel()
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client.Close()
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backendConn.Close()
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})
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extend := func() {
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timer.Reset(2 * time.Minute)
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}
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startPacketCopy(ctx, cancel, client, &net.UDPAddr{
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IP: net.ParseIP(clientRemoteAddr.Addr.String()),
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Port: int(clientRemoteAddr.Port),
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}, backendConn, ns.logf, extend)
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startPacketCopy(ctx, cancel, backendConn, backendRemoteAddr, client, ns.logf, extend)
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}
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func startPacketCopy(ctx context.Context, cancel context.CancelFunc, dst net.PacketConn, dstAddr net.Addr, src net.PacketConn, logf logger.Logf, extend func()) {
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go func() {
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defer cancel() // tear down the other direction's copy
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pkt := make([]byte, mtu)
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for {
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select {
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case <-ctx.Done():
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return
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default:
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n, srcAddr, err := src.ReadFrom(pkt)
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if err != nil {
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if ctx.Err() == nil {
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logf("read packet from %s failed: %v", srcAddr, err)
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}
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return
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}
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_, err = dst.WriteTo(pkt[:n], dstAddr)
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if err != nil {
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if ctx.Err() == nil {
|
|
logf("write packet to %s failed: %v", dstAddr, err)
|
|
}
|
|
return
|
|
}
|
|
if debugNetstack {
|
|
logf("[v2] wrote UDP packet %s -> %s", srcAddr, dstAddr)
|
|
}
|
|
extend()
|
|
}
|
|
}
|
|
}()
|
|
}
|