tsnet

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Published: Nov 30, 2023 License: BSD-3-Clause Imports: 49 Imported by: 75

Documentation

Overview

Package tsnet provides Tailscale as a library.

It is an experimental work in progress.

Example (Tshello)

Example_tshello is a full example on using tsnet. When you run this program it will print an authentication link. Open it in your favorite web browser and add it to your tailnet like any other machine. Open another terminal window and try to ping it:

$ ping tshello -c 2
PING tshello (100.105.183.159) 56(84) bytes of data.
64 bytes from tshello.your-tailnet.ts.net (100.105.183.159): icmp_seq=1 ttl=64 time=25.0 ms
64 bytes from tshello.your-tailnet.ts.net (100.105.183.159): icmp_seq=2 ttl=64 time=1.12 ms

Then connect to it using curl:

$ curl http://tshello
<html><body><h1>Hello, world!</h1>
<p>You are <b>Xe</b> from <b>pneuma</b> (100.78.40.86:49214)</p>

From here you can do anything you want with the Go standard library HTTP stack, or anything that is compatible with it (Gin/Gonic, Gorilla/mux, etc.).

package main

import (
	"flag"
	"fmt"
	"html"
	"log"
	"net/http"
	"strings"

	"tailscale.com/tsnet"
)

func firstLabel(s string) string {
	s, _, _ = strings.Cut(s, ".")
	return s
}

// Example_tshello is a full example on using tsnet. When you run this program it will print
// an authentication link. Open it in your favorite web browser and add it to your tailnet
// like any other machine. Open another terminal window and try to ping it:
//
//	$ ping tshello -c 2
//	PING tshello (100.105.183.159) 56(84) bytes of data.
//	64 bytes from tshello.your-tailnet.ts.net (100.105.183.159): icmp_seq=1 ttl=64 time=25.0 ms
//	64 bytes from tshello.your-tailnet.ts.net (100.105.183.159): icmp_seq=2 ttl=64 time=1.12 ms
//
// Then connect to it using curl:
//
//	$ curl http://tshello
//	<html><body><h1>Hello, world!</h1>
//	<p>You are <b>Xe</b> from <b>pneuma</b> (100.78.40.86:49214)</p>
//
// From here you can do anything you want with the Go standard library HTTP stack, or anything
// that is compatible with it (Gin/Gonic, Gorilla/mux, etc.).
func main() {
	var (
		addr     = flag.String("addr", ":80", "address to listen on")
		hostname = flag.String("hostname", "tshello", "hostname to use on the tailnet")
	)

	flag.Parse()
	s := new(tsnet.Server)
	s.Hostname = *hostname
	defer s.Close()
	ln, err := s.Listen("tcp", *addr)
	if err != nil {
		log.Fatal(err)
	}
	defer ln.Close()

	lc, err := s.LocalClient()
	if err != nil {
		log.Fatal(err)
	}

	log.Fatal(http.Serve(ln, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		who, err := lc.WhoIs(r.Context(), r.RemoteAddr)
		if err != nil {
			http.Error(w, err.Error(), 500)
			return
		}
		fmt.Fprintf(w, "<html><body><h1>Hello, tailnet!</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)
	})))
}
Output:

Index

Examples

Constants

This section is empty.

Variables

This section is empty.

Functions

This section is empty.

Types

type FallbackTCPHandler added in v1.52.0

type FallbackTCPHandler func(src, dst netip.AddrPort) (handler func(net.Conn), intercept bool)

FallbackTCPHandler describes the callback which conditionally handles an incoming TCP flow for the provided (src/port, dst/port) 4-tuple. These are registered as handlers of last resort, and are called only if no listener could handle the incoming flow.

If the callback returns intercept=false, the flow is rejected.

When intercept=true, the behavior depends on whether the returned handler is non-nil: if nil, the connection is rejected. If non-nil, handler takes over the TCP conn.

type FunnelOption added in v1.38.0

type FunnelOption interface {
	// contains filtered or unexported methods
}

FunnelOption is an option passed to ListenFunnel to configure the listener.

func FunnelOnly added in v1.38.0

func FunnelOnly() FunnelOption

FunnelOnly configures the listener to only respond to connections from Tailscale Funnel. The local tailnet will not be able to connect to the listener.

type Server

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.
	//
	// If you want to use multiple tsnet services in the same
	// binary, you will need to make sure that Dir is set uniquely
	// for each service. A good pattern for this is to have a
	// "base" directory (such as your mutable storage folder) and
	// then append the hostname on the end of it.
	Dir string

	// Store specifies the state store to use.
	//
	// If nil, a new FileStore is initialized at `Dir/tailscaled.state`.
	// See tailscale.com/ipn/store for supported stores.
	//
	// Logs will automatically be uploaded to log.tailscale.io,
	// where the configuration file for logging will be saved at
	// `Dir/tailscaled.log.conf`.
	Store ipn.StateStore

	// Hostname is the hostname to present to the control server.
	// If empty, the binary name is used.
	Hostname string

	// Logf, if non-nil, specifies the logger to use. By default,
	// log.Printf is used.
	Logf logger.Logf

	// Ephemeral, if true, specifies that the instance should register
	// as an Ephemeral node (https://tailscale.com/s/ephemeral-nodes).
	Ephemeral bool

	// AuthKey, if non-empty, is the auth key to create the node
	// and will be preferred over the TS_AUTHKEY environment
	// variable. If the node is already created (from state
	// previously stored in in Store), then this field is not
	// used.
	AuthKey string

	// ControlURL optionally specifies the coordination server URL.
	// If empty, the Tailscale default is used.
	ControlURL string

	// RunWebClient, if true, runs a client for managing this node over
	// its Tailscale interface on port 5252.
	RunWebClient bool

	// Port is the UDP port to listen on for WireGuard and peer-to-peer
	// traffic. If zero, a port is automatically selected. Leave this
	// field at zero unless you know what you are doing.
	Port uint16
	// contains filtered or unexported fields
}

Server is an embedded Tailscale server.

Its exported fields may be changed until the first method call.

Example

ExampleServer shows you how to construct a ready-to-use tsnet instance.

package main

import (
	"log"

	"tailscale.com/tsnet"
)

func main() {
	srv := new(tsnet.Server)
	if err := srv.Start(); err != nil {
		log.Fatalf("can't start tsnet server: %v", err)
	}
	defer srv.Close()
}
Output:

Example (Dir)

ExampleServer_dir shows you how to configure the persistent directory for a tsnet application. This is where the Tailscale node information is stored so that your application can reconnect to your tailnet when the application is restarted.

By default, tsnet will store data in your user configuration directory based on the name of the binary. Note that this folder must already exist or tsnet calls will fail.

package main

import (
	"log"
	"os"
	"path/filepath"

	"tailscale.com/tsnet"
)

func main() {
	dir := filepath.Join("/data", "tsnet")

	if err := os.MkdirAll(dir, 0700); err != nil {
		log.Fatal(err)
	}

	srv := &tsnet.Server{
		Dir: dir,
	}

	// do something with srv
	_ = srv
}
Output:

Example (Hostname)

ExampleServer_hostname shows you how to set a tsnet server's hostname.

This setting lets you control the host name of your program on your tailnet. By default this will be the name of your program (such as foo for a program stored at /usr/local/bin/foo). You can also override this by setting the Hostname field.

package main

import (
	"tailscale.com/tsnet"
)

func main() {
	srv := &tsnet.Server{
		Hostname: "kirito",
	}

	// do something with srv
	_ = srv
}
Output:

Example (IgnoreLogs)

ExampleServer_ignoreLogs shows you how to ignore all of the log messages written by a tsnet instance.

package main

import (
	"tailscale.com/tsnet"
)

func main() {
	srv := &tsnet.Server{
		Logf: func(string, ...any) {},
	}
	_ = srv
}
Output:

Example (IgnoreLogsSometimes)

ExampleServer_ignoreLogsSometimes shows you how to ignore all of the log messages written by a tsnet instance, but allows you to opt-into them if a command-line flag is set.

package main

import (
	"flag"
	"fmt"
	"log"
	"os"

	"tailscale.com/tsnet"
)

func main() {
	tsnetVerbose := flag.Bool("tsnet-verbose", false, "if set, verbosely log tsnet information")
	hostname := flag.String("tsnet-hostname", "hikari", "hostname to use on the tailnet")

	srv := &tsnet.Server{
		Hostname: *hostname,
		Logf:     func(string, ...any) {},
	}

	if *tsnetVerbose {
		srv.Logf = log.New(os.Stderr, fmt.Sprintf("[tsnet:%s] ", *hostname), log.LstdFlags).Printf
	}
}
Output:

Example (MultipleInstances)

ExampleServer_multipleInstances shows you how to configure multiple instances of tsnet per program. This allows you to have multiple Tailscale nodes in the same process/container.

package main

import (
	"log"
	"os"
	"path/filepath"

	"tailscale.com/tsnet"
)

func main() {
	baseDir := "/data"
	var servers []*tsnet.Server
	for _, hostname := range []string{"ichika", "nino", "miku", "yotsuba", "itsuki"} {
		os.MkdirAll(filepath.Join(baseDir, hostname), 0700)
		srv := &tsnet.Server{
			Hostname:  hostname,
			AuthKey:   os.Getenv("TS_AUTHKEY"),
			Ephemeral: true,
			Dir:       filepath.Join(baseDir, hostname),
		}
		if err := srv.Start(); err != nil {
			log.Fatalf("can't start tsnet server: %v", err)
		}
		servers = append(servers, srv)
	}

	// When you're done, close the instances
	defer func() {
		for _, srv := range servers {
			srv.Close()
		}
	}()
}
Output:

func (*Server) APIClient added in v1.34.0

func (s *Server) APIClient() (*tailscale.Client, error)

APIClient returns a tailscale.Client that can be used to make authenticated requests to the Tailscale control server. It requires the user to set tailscale.I_Acknowledge_This_API_Is_Unstable.

func (*Server) CapturePcap

func (s *Server) CapturePcap(ctx context.Context, pcapFile string) error

CapturePcap can be called by the application code compiled with tsnet to save a pcap of packets which the netstack within tsnet sees. This is expected to be useful during debugging, probably not useful for production.

Packets will be written to the pcap until the process exits. The pcap needs a Lua dissector to be installed in WireShark in order to decode properly: wgengine/capture/ts-dissector.lua in this repository. https://tailscale.com/kb/1023/troubleshooting/#can-i-examine-network-traffic-inside-the-encrypted-tunnel

func (*Server) CertDomains added in v1.38.0

func (s *Server) CertDomains() []string

CertDomains returns the list of domains for which the server can provide TLS certificates. These are also the DNS names for the Server. If the server is not running, it returns nil.

func (*Server) Close added in v1.24.0

func (s *Server) Close() error

Close stops the server.

It must not be called before or concurrently with Start.

func (*Server) Dial added in v1.20.0

func (s *Server) Dial(ctx context.Context, network, address string) (net.Conn, error)

Dial connects to the address on the tailnet. It will start the server if it has not been started yet.

func (*Server) HTTPClient added in v1.36.0

func (s *Server) HTTPClient() *http.Client

HTTPClient returns an HTTP client that is configured to connect over Tailscale.

This is useful if you need to have your tsnet services connect to other devices on your tailnet.

Example

ExampleServer_HTTPClient shows you how to make HTTP requests over your tailnet.

If you want to make outgoing HTTP connections to resources on your tailnet, use the HTTP client that the tsnet.Server exposes.

package main

import (
	"log"

	"tailscale.com/tsnet"
)

func main() {
	srv := &tsnet.Server{}
	cli := srv.HTTPClient()

	resp, err := cli.Get("https://hello.ts.net")
	if resp == nil {
		log.Fatal(err)
	}
	// do something with resp
	_ = resp
}
Output:

func (*Server) Listen

func (s *Server) Listen(network, addr string) (net.Listener, error)

Listen announces only on the Tailscale network. It will start the server if it has not been started yet.

Listeners which do not specify an IP address will match for traffic for the local node (that is, a destination address of the IPv4 or IPv6 address of this node) only. To listen for traffic on other addresses such as those routed inbound via subnet routes, explicitly specify the listening address or use RegisterFallbackTCPHandler.

Example

ExampleServer_Listen shows you how to create a TCP listener on your tailnet and then makes an HTTP server on top of that.

package main

import (
	"fmt"
	"log"
	"net/http"

	"tailscale.com/tsnet"
)

func main() {
	srv := &tsnet.Server{
		Hostname: "tadaima",
	}

	ln, err := srv.Listen("tcp", ":80")
	if err != nil {
		log.Fatal(err)
	}

	log.Fatal(http.Serve(ln, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintln(w, "Hi there! Welcome to the tailnet!")
	})))
}
Output:

func (*Server) ListenFunnel added in v1.38.0

func (s *Server) ListenFunnel(network, addr string, opts ...FunnelOption) (net.Listener, error)

ListenFunnel announces on the public internet using Tailscale Funnel.

It also by default listens on your local tailnet, so connections can come from either inside or outside your network. To restrict connections to be just from the internet, use the FunnelOnly option.

Currently (2023-03-10), Funnel only supports TCP on ports 443, 8443, and 10000. The supported host name is limited to that configured for the tsnet.Server. As such, the standard way to create funnel is:

s.ListenFunnel("tcp", ":443")

and the only other supported addrs currently are ":8443" and ":10000".

It will start the server if it has not been started yet.

Example

ExampleServer_ListenFunnel shows you how to create an HTTPS service on both your tailnet and the public internet via Funnel.

package main

import (
	"fmt"
	"log"
	"net/http"

	"tailscale.com/tsnet"
)

func main() {
	srv := &tsnet.Server{
		Hostname: "ophion",
	}

	ln, err := srv.ListenFunnel("tcp", ":443")
	if err != nil {
		log.Fatal(err)
	}

	log.Fatal(http.Serve(ln, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintln(w, "Hi there! Welcome to the tailnet!")
	})))
}
Output:

Example (FunnelOnly)

ExampleServer_ListenFunnel_funnelOnly shows you how to create a funnel-only HTTPS service.

package main

import (
	"fmt"
	"log"
	"net/http"

	"tailscale.com/tsnet"
)

func main() {
	srv := new(tsnet.Server)
	srv.Hostname = "ophion"
	ln, err := srv.ListenFunnel("tcp", ":443", tsnet.FunnelOnly())
	if err != nil {
		log.Fatal(err)
	}

	log.Fatal(http.Serve(ln, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintln(w, "Hi there! Welcome to the tailnet!")
	})))
}
Output:

func (*Server) ListenTLS added in v1.38.0

func (s *Server) ListenTLS(network, addr string) (net.Listener, error)

ListenTLS announces only on the Tailscale network. It returns a TLS listener wrapping the tsnet listener. It will start the server if it has not been started yet.

Example

ExampleServer_ListenTLS shows you how to create a TCP listener on your tailnet and then makes an HTTPS server on top of that.

package main

import (
	"fmt"
	"log"
	"net/http"

	"tailscale.com/tsnet"
)

func main() {
	srv := &tsnet.Server{
		Hostname: "aegis",
	}

	ln, err := srv.ListenTLS("tcp", ":443")
	if err != nil {
		log.Fatal(err)
	}

	log.Fatal(http.Serve(ln, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		fmt.Fprintln(w, "Hi there! Welcome to the tailnet!")
	})))
}
Output:

func (*Server) LocalClient added in v1.26.0

func (s *Server) LocalClient() (*tailscale.LocalClient, error)

LocalClient returns a LocalClient that speaks to s.

It will start the server if it has not been started yet. If the server's already been started successfully, it doesn't return an error.

func (*Server) Loopback added in v1.38.0

func (s *Server) Loopback() (addr string, proxyCred, localAPICred string, err error)

Loopback starts a routing server on a loopback address.

The server has multiple functions.

It can be used as a SOCKS5 proxy onto the tailnet. Authentication is required with the username "tsnet" and the value of proxyCred used as the password.

The HTTP server also serves out the "LocalAPI" on /localapi. As the LocalAPI is powerful, access to endpoints requires BOTH passing a "Sec-Tailscale: localapi" HTTP header and passing localAPICred as basic auth.

If you only need to use the LocalAPI from Go, then prefer LocalClient as it does not require communication via TCP.

func (*Server) RegisterFallbackTCPHandler added in v1.52.0

func (s *Server) RegisterFallbackTCPHandler(cb FallbackTCPHandler) func()

RegisterFallbackTCPHandler registers a callback which will be called to handle a TCP flow to this tsnet node, for which no listeners will handle.

If multiple fallback handlers are registered, they will be called in an undefined order. See FallbackTCPHandler for details on handling a flow.

The returned function can be used to deregister this callback.

func (*Server) Start added in v1.20.0

func (s *Server) Start() error

Start connects the server to the tailnet. Optional: any calls to Dial/Listen will also call Start.

Example

ExampleServer_Start demonstrates the Start method, which should be called if you need to explicitly start it. Note that the Start method is implicitly called if needed.

package main

import (
	"log"

	"tailscale.com/tsnet"
)

func main() {
	srv := new(tsnet.Server)

	if err := srv.Start(); err != nil {
		log.Fatal(err)
	}

	// Be sure to close the server instance at some point. It will stay open until
	// either the OS process ends or the server is explicitly closed.
	defer srv.Close()
}
Output:

func (*Server) TailscaleIPs added in v1.38.0

func (s *Server) TailscaleIPs() (ip4, ip6 netip.Addr)

TailscaleIPs returns IPv4 and IPv6 addresses for this node. If the node has not yet joined a tailnet or is otherwise unaware of its own IP addresses, the returned ip4, ip6 will be !netip.IsValid().

func (*Server) Up added in v1.38.0

func (s *Server) Up(ctx context.Context) (*ipnstate.Status, error)

Up connects the server to the tailnet and waits until it is running. On success it returns the current status, including a Tailscale IP address.

Directories

Path Synopsis
example
tshello
The tshello server demonstrates how to use Tailscale as a library.
The tshello server demonstrates how to use Tailscale as a library.
tsnet-funnel
The tsnet-funnel server demonstrates how to use tsnet with Funnel.
The tsnet-funnel server demonstrates how to use tsnet with Funnel.
tsnet-http-client
The tshello server demonstrates how to use Tailscale as a library.
The tshello server demonstrates how to use Tailscale as a library.
web-client
The web-client command demonstrates serving the Tailscale web client over tsnet.
The web-client command demonstrates serving the Tailscale web client over tsnet.

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