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net/tsdial: give netstack a Dialer, start refactoring name resolution

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This starts to refactor tsdial.Dialer's name resolution to have
different stages: in-memory MagicDNS vs system resolution. A future
change will plug in ExitDNS resolution.

This also plumbs a Dialer into netstack and unexports the dnsMap
internals.

And it removes some of the async AddNetworkMapCallback usage and
replaces it with synchronous updates of the Dialer's netmap
from LocalBackend, since the LocalBackend has the Dialer too.

Updates #3475

Change-Id: Idcb7b1169878c74f0522f5151031ccbc49fe4cb4
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
bradfitz/demo_client_hijack
Brad Fitzpatrick 3 years ago committed by Brad Fitzpatrick
parent 768baafcb5
commit adc5997592
10 changed files with 99 additions and 83 deletions
Show Stats Download Patch File Download Diff File

6
cmd/tailscaled/tailscaled.go
Unescape Escape View File

@ -317,7 +317,7 @@ func run() error {
panic("internal error: exit node resolver not wired up")
}
ns, err := newNetstack(logf, e)
ns, err := newNetstack(logf, dialer, e)
if err != nil {
return fmt.Errorf("newNetstack: %w", err)
}
@ -525,12 +525,12 @@ func runDebugServer(mux *http.ServeMux, addr string) {
}
}
func newNetstack(logf logger.Logf, e wgengine.Engine) (*netstack.Impl, error) {
func newNetstack(logf logger.Logf, dialer *tsdial.Dialer, e wgengine.Engine) (*netstack.Impl, error) {
tunDev, magicConn, ok := e.(wgengine.InternalsGetter).GetInternals()
if !ok {
return nil, fmt.Errorf("%T is not a wgengine.InternalsGetter", e)
}
return netstack.Create(logf, tunDev, e, magicConn)
return netstack.Create(logf, tunDev, e, magicConn, dialer)
}
// mustStartProxyListeners creates listeners for local SOCKS and HTTP

7
cmd/tailscaled/tailscaled_windows.go
Unescape Escape View File

@ -32,6 +32,7 @@ import (
"tailscale.com/ipn/ipnserver"
"tailscale.com/logpolicy"
"tailscale.com/net/dns"
"tailscale.com/net/tsdial"
"tailscale.com/net/tstun"
"tailscale.com/safesocket"
"tailscale.com/types/logger"
@ -182,6 +183,7 @@ func startIPNServer(ctx context.Context, logid string) error {
if err != nil {
return err
}
dialer := new(tsdial.Dialer)
getEngineRaw := func() (wgengine.Engine, error) {
dev, devName, err := tstun.New(logf, "Tailscale")
@ -208,13 +210,14 @@ func startIPNServer(ctx context.Context, logid string) error {
DNS: d,
ListenPort: 41641,
LinkMonitor: linkMon,
Dialer: dialer,
})
if err != nil {
r.Close()
dev.Close()
return nil, fmt.Errorf("engine: %w", err)
}
ns, err := newNetstack(logf, eng)
ns, err := newNetstack(logf, dialer, eng)
if err != nil {
return nil, fmt.Errorf("newNetstack: %w", err)
}
@ -294,7 +297,7 @@ func startIPNServer(ctx context.Context, logid string) error {
return fmt.Errorf("safesocket.Listen: %v", err)
}
err = ipnserver.Run(ctx, logf, ln, store, linkMon, logid, getEngine, ipnServerOpts())
err = ipnserver.Run(ctx, logf, ln, store, linkMon, dialer, logid, getEngine, ipnServerOpts())
if err != nil {
logf("ipnserver.Run: %v", err)
}

4
ipn/ipnlocal/local.go
Unescape Escape View File

@ -165,9 +165,6 @@ func NewLocalBackend(logf logger.Logf, logid string, store ipn.StateStore, diale
if dialer == nil {
dialer = new(tsdial.Dialer)
}
e.AddNetworkMapCallback(func(nm *netmap.NetworkMap) {
dialer.SetDNSMap(tsdial.DNSMapFromNetworkMap(nm))
})
osshare.SetFileSharingEnabled(false, logf)
@ -2679,6 +2676,7 @@ func hasCapability(nm *netmap.NetworkMap, cap string) bool {
}
func (b *LocalBackend) setNetMapLocked(nm *netmap.NetworkMap) {
b.dialer.SetNetMap(nm)
var login string
if nm != nil {
login = nm.UserProfiles[nm.User].LoginName

8
ipn/ipnserver/server.go
Unescape Escape View File

@ -43,7 +43,6 @@ import (
"tailscale.com/safesocket"
"tailscale.com/smallzstd"
"tailscale.com/types/logger"
"tailscale.com/types/netmap"
"tailscale.com/util/groupmember"
"tailscale.com/util/pidowner"
"tailscale.com/util/systemd"
@ -654,7 +653,7 @@ func StateStore(path string, logf logger.Logf) (ipn.StateStore, error) {
// The getEngine func is called repeatedly, once per connection, until it returns an engine successfully.
//
// Deprecated: use New and Server.Run instead.
func Run(ctx context.Context, logf logger.Logf, ln net.Listener, store ipn.StateStore, linkMon *monitor.Mon, logid string, getEngine func() (wgengine.Engine, error), opts Options) error {
func Run(ctx context.Context, logf logger.Logf, ln net.Listener, store ipn.StateStore, linkMon *monitor.Mon, dialer *tsdial.Dialer, logid string, getEngine func() (wgengine.Engine, error), opts Options) error {
getEngine = getEngineUntilItWorksWrapper(getEngine)
runDone := make(chan struct{})
defer close(runDone)
@ -738,11 +737,6 @@ func Run(ctx context.Context, logf logger.Logf, ln net.Listener, store ipn.State
}
}
dialer := new(tsdial.Dialer)
eng.AddNetworkMapCallback(func(nm *netmap.NetworkMap) {
dialer.SetDNSMap(tsdial.DNSMapFromNetworkMap(nm))
})
server, err := New(logf, logid, store, eng, dialer, serverModeUser, opts)
if err != nil {
return err

3
ipn/ipnserver/server_test.go
Unescape Escape View File

@ -13,6 +13,7 @@ import (
"tailscale.com/ipn"
"tailscale.com/ipn/ipnserver"
"tailscale.com/net/tsdial"
"tailscale.com/safesocket"
"tailscale.com/wgengine"
)
@ -72,6 +73,6 @@ func TestRunMultipleAccepts(t *testing.T) {
}
defer ln.Close()
err = ipnserver.Run(ctx, logTriggerTestf, ln, store, nil /* mon */, "dummy_logid", ipnserver.FixedEngine(eng), opts)
err = ipnserver.Run(ctx, logTriggerTestf, ln, store, nil /* mon */, new(tsdial.Dialer), "dummy_logid", ipnserver.FixedEngine(eng), opts)
t.Logf("ipnserver.Run = %v", err)
}

67
net/tsdial/dnsmap.go
Unescape Escape View File

@ -6,6 +6,7 @@ package tsdial
import (
"context"
"errors"
"fmt"
"net"
"strconv"
@ -16,15 +17,18 @@ import (
"tailscale.com/util/dnsname"
)
// DNSMap maps MagicDNS names (both base + FQDN) to their first IP.
// dnsMap maps MagicDNS names (both base + FQDN) to their first IP.
// It must not be mutated once created.
//
// Example keys are "foo.domain.tld.beta.tailscale.net" and "foo",
// both without trailing dots.
type DNSMap map[string]netaddr.IP
type dnsMap map[string]netaddr.IP
func DNSMapFromNetworkMap(nm *netmap.NetworkMap) DNSMap {
ret := make(DNSMap)
func dnsMapFromNetworkMap(nm *netmap.NetworkMap) dnsMap {
if nm == nil {
return nil
}
ret := make(dnsMap)
suffix := nm.MagicDNSSuffix()
have4 := false
if nm.Name != "" && len(nm.Addresses) > 0 {
@ -68,26 +72,35 @@ func DNSMapFromNetworkMap(nm *netmap.NetworkMap) DNSMap {
return ret
}
// errUnresolved is a sentinel error returned by dnsMap.resolveMemory.
var errUnresolved = errors.New("address well formed but not resolved")
func splitHostPort(addr string) (host string, port uint16, err error) {
host, portStr, err := net.SplitHostPort(addr)
if err != nil {
return "", 0, err
}
port16, err := strconv.ParseUint(portStr, 10, 16)
if err != nil {
return "", 0, fmt.Errorf("invalid port in address %q", addr)
}
return host, uint16(port16), nil
}
// Resolve resolves addr into an IP:port using first the MagicDNS contents
// of m, else using the system resolver.
func (m DNSMap) Resolve(ctx context.Context, addr string) (netaddr.IPPort, error) {
ipp, pippErr := netaddr.ParseIPPort(addr)
if pippErr == nil {
return ipp, nil
}
host, port, err := net.SplitHostPort(addr)
//
// The error is [exactly] errUnresolved if the addr is a name that isn't known
// in the map.
func (m dnsMap) resolveMemory(ctx context.Context, network, addr string) (_ netaddr.IPPort, err error) {
host, port, err := splitHostPort(addr)
if err != nil {
// addr is malformed.
// addr malformed or invalid port.
return netaddr.IPPort{}, err
}
if _, err := netaddr.ParseIP(host); err == nil {
// The host part of addr was an IP, so the netaddr.ParseIPPort above should've
// passed. Must've been a bad port number. Return the original error.
return netaddr.IPPort{}, pippErr
}
port16, err := strconv.ParseUint(port, 10, 16)
if err != nil {
return netaddr.IPPort{}, fmt.Errorf("invalid port in address %q", addr)
if ip, err := netaddr.ParseIP(host); err == nil {
// addr was literal ip:port.
return netaddr.IPPortFrom(ip, port), nil
}
// Host is not an IP, so assume it's a DNS name.
@ -95,20 +108,8 @@ func (m DNSMap) Resolve(ctx context.Context, addr string) (netaddr.IPPort, error
// Try MagicDNS first, otherwise a real DNS lookup.
ip := m[host]
if !ip.IsZero() {
return netaddr.IPPortFrom(ip, uint16(port16)), nil
return netaddr.IPPortFrom(ip, port), nil
}
// TODO(bradfitz): wire up net/dnscache too.
// No MagicDNS name so try real DNS.
var r net.Resolver
ips, err := r.LookupIP(ctx, "ip", host)
if err != nil {
return netaddr.IPPort{}, err
}
if len(ips) == 0 {
return netaddr.IPPort{}, fmt.Errorf("DNS lookup returned no results for %q", host)
}
ip, _ = netaddr.FromStdIP(ips[0])
return netaddr.IPPortFrom(ip, uint16(port16)), nil
return netaddr.IPPort{}, errUnresolved
}

10
net/tsdial/dnsmap_test.go
Unescape Escape View File

@ -19,7 +19,7 @@ func TestDNSMapFromNetworkMap(t *testing.T) {
tests := []struct {
name string
nm *netmap.NetworkMap
want DNSMap
want dnsMap
}{
{
name: "self",
@ -30,7 +30,7 @@ func TestDNSMapFromNetworkMap(t *testing.T) {
pfx("100::123/128"),
},
},
want: DNSMap{
want: dnsMap{
"foo": ip("100.102.103.104"),
"foo.tailnet": ip("100.102.103.104"),
},
@ -59,7 +59,7 @@ func TestDNSMapFromNetworkMap(t *testing.T) {
},
},
},
want: DNSMap{
want: dnsMap{
"foo": ip("100.102.103.104"),
"foo.tailnet": ip("100.102.103.104"),
"a": ip("100.0.0.201"),
@ -91,7 +91,7 @@ func TestDNSMapFromNetworkMap(t *testing.T) {
},
},
},
want: DNSMap{
want: dnsMap{
"foo": ip("100::123"),
"foo.tailnet": ip("100::123"),
"a": ip("100::201"),
@ -103,7 +103,7 @@ func TestDNSMapFromNetworkMap(t *testing.T) {
}
for _, tt := range tests {
t.Run(tt.name, func(t *testing.T) {
got := DNSMapFromNetworkMap(tt.nm)
got := dnsMapFromNetworkMap(tt.nm)
if !reflect.DeepEqual(got, tt.want) {
t.Errorf("mismatch:\n got %v\nwant %v\n", got, tt.want)
}

46
net/tsdial/tsdial.go
Unescape Escape View File

@ -18,6 +18,7 @@ import (
"inet.af/netaddr"
"tailscale.com/net/netknob"
"tailscale.com/types/netmap"
"tailscale.com/wgengine/monitor"
)
@ -43,7 +44,7 @@ type Dialer struct {
peerDialer *net.Dialer
mu sync.Mutex
dns DNSMap
dns dnsMap
tunName string // tun device name
linkMon *monitor.Mon
}
@ -102,26 +103,55 @@ func (d *Dialer) PeerDialControlFunc() func(network, address string, c syscall.R
return peerDialControlFunc(d)
}
// SetDNSMap sets the current map of DNS names learned from the netmap.
func (d *Dialer) SetDNSMap(m DNSMap) {
// TODO(bradfitz): update this to be aware of DNSConfig
// ExtraNames and CertDomains.
// SetNetMap sets the current network map and notably, the DNS names
// in its DNS configuration.
func (d *Dialer) SetNetMap(nm *netmap.NetworkMap) {
m := dnsMapFromNetworkMap(nm)
d.mu.Lock()
defer d.mu.Unlock()
d.dns = m
}
func (d *Dialer) resolve(ctx context.Context, addr string) (netaddr.IPPort, error) {
func (d *Dialer) Resolve(ctx context.Context, network, addr string) (netaddr.IPPort, error) {
d.mu.Lock()
dns := d.dns
d.mu.Unlock()
return dns.Resolve(ctx, addr)
// MagicDNS or otherwise baked in to the NetworkMap? Try that first.
ipp, err := dns.resolveMemory(ctx, network, addr)
if err != errUnresolved {
return ipp, err
}
// Otherwise, hit the network.
// TODO(bradfitz): use ExitDNS (Issue 3475)
// TODO(bradfitz): wire up net/dnscache too.
host, port, err := splitHostPort(addr)
if err != nil {
// addr is malformed.
return netaddr.IPPort{}, err
}
var r net.Resolver
ips, err := r.LookupIP(ctx, network, host)
if err != nil {
return netaddr.IPPort{}, err
}
if len(ips) == 0 {
return netaddr.IPPort{}, fmt.Errorf("DNS lookup returned no results for %q", host)
}
ip, _ := netaddr.FromStdIP(ips[0])
return netaddr.IPPortFrom(ip, port), nil
}
// UserDial connects to the provided network address as if a user were initiating the dial.
// (e.g. from a SOCKS or HTTP outbound proxy)
func (d *Dialer) UserDial(ctx context.Context, network, addr string) (net.Conn, error) {
ipp, err := d.resolve(ctx, addr)
ipp, err := d.Resolve(ctx, network, addr)
if err != nil {
return nil, err
}

2
tsnet/tsnet.go
Unescape Escape View File

@ -132,7 +132,7 @@ func (s *Server) start() error {
return fmt.Errorf("%T is not a wgengine.InternalsGetter", eng)
}
ns, err := netstack.Create(logf, tunDev, eng, magicConn)
ns, err := netstack.Create(logf, tunDev, eng, magicConn, dialer)
if err != nil {
return fmt.Errorf("netstack.Create: %w", err)
}

27
wgengine/netstack/netstack.go
Unescape Escape View File

@ -71,6 +71,7 @@ type Impl struct {
e wgengine.Engine
mc *magicsock.Conn
logf logger.Logf
dialer *tsdial.Dialer
// atomicIsLocalIPFunc holds a func that reports whether an IP
// is a local (non-subnet) Tailscale IP address of this
@ -79,7 +80,6 @@ type Impl struct {
atomicIsLocalIPFunc atomic.Value // of func(netaddr.IP) bool
mu sync.Mutex
dns tsdial.DNSMap
// connsOpenBySubnetIP keeps track of number of connections open
// for each subnet IP temporarily registered on netstack for active
// TCP connections, so they can be unregistered when connections are
@ -91,7 +91,7 @@ const nicID = 1
const mtu = 1500
// Create creates and populates a new Impl.
func Create(logf logger.Logf, tundev *tstun.Wrapper, e wgengine.Engine, mc *magicsock.Conn) (*Impl, error) {
func Create(logf logger.Logf, tundev *tstun.Wrapper, e wgengine.Engine, mc *magicsock.Conn, dialer *tsdial.Dialer) (*Impl, error) {
if mc == nil {
return nil, errors.New("nil magicsock.Conn")
}
@ -104,6 +104,9 @@ func Create(logf logger.Logf, tundev *tstun.Wrapper, e wgengine.Engine, mc *magi
if e == nil {
return nil, errors.New("nil Engine")
}
if dialer == nil {
return nil, errors.New("nil Dialer")
}
ipstack := stack.New(stack.Options{
NetworkProtocols: []stack.NetworkProtocolFactory{ipv4.NewProtocol, ipv6.NewProtocol},
TransportProtocols: []stack.TransportProtocolFactory{tcp.NewProtocol, udp.NewProtocol, icmp.NewProtocol4, icmp.NewProtocol6},
@ -139,6 +142,7 @@ func Create(logf logger.Logf, tundev *tstun.Wrapper, e wgengine.Engine, mc *magi
tundev: tundev,
e: e,
mc: mc,
dialer: dialer,
connsOpenBySubnetIP: make(map[netaddr.IP]int),
}
ns.atomicIsLocalIPFunc.Store(tsaddr.NewContainsIPFunc(nil))
@ -179,12 +183,6 @@ func (ns *Impl) Start() error {
return nil
}
func (ns *Impl) updateDNS(nm *netmap.NetworkMap) {
ns.mu.Lock()
defer ns.mu.Unlock()
ns.dns = tsdial.DNSMapFromNetworkMap(nm)
}
func (ns *Impl) addSubnetAddress(ip netaddr.IP) {
ns.mu.Lock()
ns.connsOpenBySubnetIP[ip]++
@ -230,7 +228,6 @@ func ipPrefixToAddressWithPrefix(ipp netaddr.IPPrefix) tcpip.AddressWithPrefix {
func (ns *Impl) updateIPs(nm *netmap.NetworkMap) {
ns.atomicIsLocalIPFunc.Store(tsaddr.NewContainsIPFunc(nm.Addresses))
ns.updateDNS(nm)
oldIPs := make(map[tcpip.AddressWithPrefix]bool)
for _, protocolAddr := range ns.ipstack.AllAddresses()[nicID] {
@ -299,11 +296,7 @@ func (ns *Impl) updateIPs(nm *netmap.NetworkMap) {
}
func (ns *Impl) DialContextTCP(ctx context.Context, addr string) (*gonet.TCPConn, error) {
ns.mu.Lock()
dnsMap := ns.dns
ns.mu.Unlock()
remoteIPPort, err := dnsMap.Resolve(ctx, addr)
remoteIPPort, err := ns.dialer.Resolve(ctx, "tcp", addr)
if err != nil {
return nil, err
}
@ -323,11 +316,7 @@ func (ns *Impl) DialContextTCP(ctx context.Context, addr string) (*gonet.TCPConn
}
func (ns *Impl) DialContextUDP(ctx context.Context, addr string) (*gonet.UDPConn, error) {
ns.mu.Lock()
dnsMap := ns.dns
ns.mu.Unlock()
remoteIPPort, err := dnsMap.Resolve(ctx, addr)
remoteIPPort, err := ns.dialer.Resolve(ctx, "udp", addr)
if err != nil {
return nil, err
}

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