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tsnet: add Tailscale-as-a-library package

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Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
This commit is contained in:
Brad Fitzpatrick 2021-05-14 08:53:55 -07:00 committed by Brad Fitzpatrick
parent 6f62bbae79
commit 5b52b64094
3 changed files with 329 additions and 2 deletions
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43
tsnet/example/tshello/tshello.go Normal file
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@ -0,0 +1,43 @@
// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// The tshello server demonstrates how to use Tailscale as a library.
package main
import (
"fmt"
"html"
"log"
"net/http"
"strings"
"tailscale.com/tsnet"
)
func main() {
s := new(tsnet.Server)
ln, err := s.Listen("tcp", ":80")
if err != nil {
log.Fatal(err)
}
log.Fatal(http.Serve(ln, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
who, ok := s.WhoIs(r.RemoteAddr)
if !ok {
http.Error(w, "WhoIs failed", 500)
return
}
fmt.Fprintf(w, "<html><body><h1>Hello, world!</h1>\n")
fmt.Fprintf(w, "<p>You are <b>%s</b> from <b>%s</b> (%s)</p>",
html.EscapeString(who.UserProfile.LoginName),
html.EscapeString(firstLabel(who.Node.ComputedName)),
r.RemoteAddr)
})))
}
func firstLabel(s string) string {
if i := strings.Index(s, "."); i != -1 {
return s[:i]
}
return s
}

274
tsnet/tsnet.go Normal file
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@ -0,0 +1,274 @@
// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// Package tsnet provides Tailscale as a library.
//
// It is an experimental work in progress.
package tsnet
import (
"errors"
"fmt"
"log"
"net"
"os"
"path/filepath"
"strconv"
"strings"
"sync"
"time"
"inet.af/netaddr"
"tailscale.com/client/tailscale/apitype"
"tailscale.com/control/controlclient"
"tailscale.com/ipn"
"tailscale.com/ipn/ipnlocal"
"tailscale.com/smallzstd"
"tailscale.com/types/logger"
"tailscale.com/wgengine"
"tailscale.com/wgengine/monitor"
"tailscale.com/wgengine/netstack"
)
// Server is an embedded Tailscale server.
//
// Its exported fields may be changed until the first call to Listen.
type Server struct {
// Dir specifies the name of the directory to use for
// state. If empty, a directory is selected automatically
// under os.UserConfigDir (https://golang.org/pkg/os/#UserConfigDir).
// based on the name of the binary.
Dir string
// Hostname is the hostname to present to the control server.
// If empty, the binary name is used.l
Hostname string
// Logf, if non-nil, specifies the logger to use. By default,
// log.Printf is used.
Logf logger.Logf
initOnce sync.Once
initErr error
lb *ipnlocal.LocalBackend
// the state directory
dir string
hostname string
mu sync.Mutex
listeners map[listenKey]*listener
}
// WhoIs reports the node and user who owns the node with the given
// address. The addr may be an ip:port (as from an
// http.Request.RemoteAddr) or just an IP address.
func (s *Server) WhoIs(addr string) (w *apitype.WhoIsResponse, ok bool) {
ipp, err := netaddr.ParseIPPort(addr)
if err != nil {
ip, err := netaddr.ParseIP(addr)
if err != nil {
return nil, false
}
ipp.IP = ip
}
n, up, ok := s.lb.WhoIs(ipp)
if !ok {
return nil, false
}
return &apitype.WhoIsResponse{
Node: n,
UserProfile: &up,
}, true
}
func (s *Server) doInit() {
if err := s.start(); err != nil {
s.initErr = fmt.Errorf("tsnet: %w", err)
}
}
func (s *Server) start() error {
if v, _ := strconv.ParseBool(os.Getenv("TAILSCALE_USE_WIP_CODE")); !v {
return errors.New("code disabled without environment variable TAILSCALE_USE_WIP_CODE set true")
}
exe, err := os.Executable()
if err != nil {
return err
}
prog := strings.TrimSuffix(strings.ToLower(filepath.Base(exe)), ".exe")
s.hostname = s.Hostname
if s.hostname == "" {
s.hostname = prog
}
s.dir = s.Dir
if s.dir == "" {
confDir, err := os.UserConfigDir()
if err != nil {
return err
}
s.dir = filepath.Join(confDir, "tslib-"+prog)
if err := os.MkdirAll(s.dir, 0700); err != nil {
return err
}
}
if fi, err := os.Stat(s.dir); err != nil {
return err
} else if !fi.IsDir() {
return fmt.Errorf("%v is not a directory", s.dir)
}
logf := s.Logf
if logf == nil {
logf = log.Printf
}
// TODO(bradfitz): start logtail? don't use filch, perhaps?
// only upload plumbed Logf?
linkMon, err := monitor.New(logf)
if err != nil {
return err
}
eng, err := wgengine.NewUserspaceEngine(logf, wgengine.Config{
ListenPort: 0,
LinkMonitor: linkMon,
})
if err != nil {
return err
}
tunDev, magicConn, ok := eng.(wgengine.InternalsGetter).GetInternals()
if !ok {
return fmt.Errorf("%T is not a wgengine.InternalsGetter", eng)
}
ns, err := netstack.Create(logf, tunDev, eng, magicConn, false)
if err != nil {
return fmt.Errorf("netstack.Create: %w", err)
}
ns.ForwardTCPIn = s.forwardTCP
if err := ns.Start(); err != nil {
return fmt.Errorf("failed to start netstack: %w", err)
}
statePath := filepath.Join(s.dir, "tailscaled.state")
store, err := ipn.NewFileStore(statePath)
if err != nil {
return err
}
logid := "tslib-TODO"
lb, err := ipnlocal.NewLocalBackend(logf, logid, store, eng)
if err != nil {
return fmt.Errorf("NewLocalBackend: %v", err)
}
s.lb = lb
lb.SetDecompressor(func() (controlclient.Decompressor, error) {
return smallzstd.NewDecoder(nil)
})
prefs := ipn.NewPrefs()
prefs.Hostname = s.hostname
prefs.WantRunning = true
err = lb.Start(ipn.Options{
StateKey: ipn.GlobalDaemonStateKey,
UpdatePrefs: prefs,
})
if err != nil {
return fmt.Errorf("starting backend: %w", err)
}
if os.Getenv("TS_LOGIN") == "1" {
s.lb.StartLoginInteractive()
}
return nil
}
func (s *Server) forwardTCP(c net.Conn, port uint16) {
s.mu.Lock()
ln, ok := s.listeners[listenKey{"tcp", "", fmt.Sprint(port)}]
s.mu.Unlock()
if !ok {
c.Close()
return
}
t := time.NewTimer(time.Second)
defer t.Stop()
select {
case ln.conn <- c:
case <-t.C:
c.Close()
}
}
func (s *Server) Listen(network, addr string) (net.Listener, error) {
host, port, err := net.SplitHostPort(addr)
if err != nil {
return nil, fmt.Errorf("tsnet: %w", err)
}
s.initOnce.Do(s.doInit)
if s.initErr != nil {
return nil, s.initErr
}
key := listenKey{network, host, port}
ln := &listener{
s: s,
key: key,
addr: addr,
conn: make(chan net.Conn),
}
s.mu.Lock()
if s.listeners == nil {
s.listeners = map[listenKey]*listener{}
}
if _, ok := s.listeners[key]; ok {
s.mu.Unlock()
return nil, fmt.Errorf("tsnet: listener already open for %s, %s", network, addr)
}
s.listeners[key] = ln
s.mu.Unlock()
return ln, nil
}
type listenKey struct {
network string
host string
port string
}
type listener struct {
s *Server
key listenKey
addr string
conn chan net.Conn
}
func (ln *listener) Accept() (net.Conn, error) {
c, ok := <-ln.conn
if !ok {
return nil, fmt.Errorf("tsnet: %w", net.ErrClosed)
}
return c, nil
}
func (ln *listener) Addr() net.Addr { return addr{ln} }
func (ln *listener) Close() error {
ln.s.mu.Lock()
defer ln.s.mu.Unlock()
if v, ok := ln.s.listeners[ln.key]; ok && v == ln {
delete(ln.s.listeners, ln.key)
close(ln.conn)
}
return nil
}
type addr struct{ ln *listener }
func (a addr) Network() string { return a.ln.key.network }
func (a addr) String() string { return a.ln.addr }

14
wgengine/netstack/netstack.go
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@ -48,6 +48,12 @@
// and implements wgengine.FakeImpl to act as a userspace network // and implements wgengine.FakeImpl to act as a userspace network
// stack when Tailscale is running in fake mode. // stack when Tailscale is running in fake mode.
type Impl struct { type Impl struct {
// ForwardTCPIn, if non-nil, handles forwarding an inbound TCP
// connection.
// TODO(bradfitz): provide mechanism for tsnet to reject a
// port other than accepting it and closing it.
ForwardTCPIn func(c net.Conn, port uint16)
ipstack *stack.Stack ipstack *stack.Stack
linkEP *channel.Endpoint linkEP *channel.Endpoint
tundev *tstun.Wrapper tundev *tstun.Wrapper
@ -441,11 +447,15 @@ func (ns *Impl) acceptTCP(r *tcp.ForwarderRequest) {
r.Complete(true) r.Complete(true)
return return
} }
r.Complete(false)
c := gonet.NewTCPConn(&wq, ep)
if ns.ForwardTCPIn != nil {
ns.ForwardTCPIn(c, reqDetails.LocalPort)
return
}
if isTailscaleIP { if isTailscaleIP {
dialAddr = tcpip.Address(net.ParseIP("127.0.0.1")).To4() dialAddr = tcpip.Address(net.ParseIP("127.0.0.1")).To4()
} }
r.Complete(false)
c := gonet.NewTCPConn(&wq, ep)
ns.forwardTCP(c, &wq, dialAddr, reqDetails.LocalPort) ns.forwardTCP(c, &wq, dialAddr, reqDetails.LocalPort)
} }