Output server details as json (#37)

This PR changes the address url stdout to be in json format and lets
tsrelay come up with its own once by default. This way, we can add more
details that a client such as vscode might need to extract out of
tsrelay at server startup.

Author: marwan-at-work

src/tailscale/cli.ts

@@ -1,9 +1,8 @@
 import * as cp from 'child_process';
 import * as vscode from 'vscode';
 import fetch from 'node-fetch';
-import { getNonce } from '../get-nonce';
 import * as WebSocket from 'ws';
-import type { ServeParams, ServeConfig, ServeStatus } from '../types';
+import type { ServeParams, ServeStatus, TSRelayDetails } from '../types';
 import { Logger } from '../logger';
 import * as path from 'node:path';
 import { LogLevel } from 'vscode';
@@ -26,14 +25,13 @@ interface vscodeModule {
 
 export class Tailscale {
   private _vscode: vscodeModule;
-  private nonce: string;
+  private nonce?: string;
   public url?: string;
   public authkey?: string;
   private childProcess?: cp.ChildProcess;
 
   constructor(vscode: vscodeModule) {
     this._vscode = vscode;
-    this.nonce = getNonce();
   }
 
   static async withInit(vscode: vscodeModule): Promise<Tailscale> {
@@ -58,7 +56,7 @@ export class Tailscale {
         __dirname,
         `../bin/vscode-tailscale_${platform}_${arch}/vscode-tailscale`
       );
-      let args = [`-nonce=${this.nonce}`];
+      let args = [];
       if (this._vscode.env.logLevel === LogLevel.Debug) {
         args.push('-v');
       }
@@ -82,7 +80,9 @@ export class Tailscale {
 
       if (this.childProcess.stdout) {
         this.childProcess.stdout.on('data', (data: Buffer) => {
-          this.url = data.toString().trim();
+          const details = JSON.parse(data.toString().trim()) as TSRelayDetails;
+          this.url = details.address;
+          this.nonce = details.nonce;
           this.authkey = Buffer.from(`${this.nonce}:`).toString('base64');
           Logger.info(`url: ${this.url}`, LOG_COMPONENT);
 

src/types.ts

@@ -152,3 +152,8 @@ export interface NewPortNotification {
   message: string;
   port: number;
 }
+
+export interface TSRelayDetails {
+  address: string;
+  nonce: string;
+}

tsrelay/main.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"math/rand"
 	"net"
 	"net/http"
 	"net/url"
@@ -74,12 +75,14 @@ func run() error {
 	ctx, cancel := signal.NotifyContext(context.Background(), os.Interrupt)
 	defer cancel()
 
-	if *nonce == "" {
-		return errors.New("missing nonce as first argument")
-	}
 	return runHTTPServer(ctx, lggr, *port, *nonce)
 }
 
+type serverDetails struct {
+	Address string `json:"address,omitempty"`
+	Nonce   string `json:"nonce,omitempty"`
+}
+
 func runHTTPServer(ctx context.Context, lggr *logger, port int, nonce string) error {
 	l, err := net.Listen("tcp", fmt.Sprintf("127.0.0.1:%d", port))
 	if err != nil {
@@ -89,7 +92,12 @@ func runHTTPServer(ctx context.Context, lggr *logger, port int, nonce string) er
 	if err != nil {
 		return fmt.Errorf("error parsing addr %q: %w", l.Addr().String(), err)
 	}
-	fmt.Fprintf(os.Stdout, "http://127.0.0.1:%s\n", u.Port())
+	sd := serverDetails{Address: fmt.Sprintf("http://127.0.0.1:%s", u.Port())}
+	if nonce == "" {
+		nonce = getNonce()
+		sd.Nonce = nonce // only print it out if not set by flag
+	}
+	json.NewEncoder(os.Stdout).Encode(sd)
 	s := &http.Server{
 		Handler: &httpHandler{
 			lc: tailscale.LocalClient{
@@ -105,6 +113,15 @@ func runHTTPServer(ctx context.Context, lggr *logger, port int, nonce string) er
 	return serveTLS(ctx, l, s, time.Second)
 }
 
+func getNonce() string {
+	const possible = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789"
+	var b strings.Builder
+	for i := 0; i < 32; i++ {
+		b.WriteByte(possible[rand.Intn(len(possible))])
+	}
+	return b.String()
+}
+
 type httpHandler struct {
 	sync.Mutex
 	nonce        string