Persistent hidden service in golang

Question

Im trying to host a hidden service in golang using github.com/cretz/bine/tor. But every time I start my program a new hidden service (with new .onion adress) is started instead of the previous hidden service.

This is the code Im using

package main

import (
    "context"
    "fmt"
    "github.com/cretz/bine/tor"
    "log"
    "net/http"
    "time"
)

func main() {
    // Start tor with default config
    fmt.Println("Starting and registering onion service, please wait a couple of minutes...")
    t, err := tor.Start(nil, nil)
    if err != nil {
        log.Panicf("Unable to start Tor: %v", err)
    }
    defer t.Close()
    // Wait at most a few minutes to publish the service
    listenCtx, listenCancel := context.WithTimeout(context.Background(), 3*time.Minute)
    defer listenCancel()
    // Create a v3 onion service
    onion, err := t.Listen(listenCtx, &tor.ListenConf{Version3: true, RemotePorts: []int{80}})
    if err != nil {
        log.Panicf("Unable to create onion service: %v", err)
    }
    defer onion.Close()
    fmt.Printf("Open Tor browser and navigate to http://%v.onion\n", onion.ID)
    fmt.Println("Press enter to exit")
    // Serve the current folder from HTTP
    errCh := make(chan error, 1)
    go func() { errCh <- http.Serve(onion, http.FileServer(http.Dir("."))) }()
    // End when enter is pressed
    go func() {
        fmt.Scanln()
        errCh <- nil
    }()
    if err = <-errCh; err != nil {
        log.Panicf("Failed serving: %v", err)
    }
}

I tryed this to force the program using the same DataDir

t, err := tor.Start(nil, &tor.StartConf{DataDir: "data-dir"})

but this wont work.

Answer 1

You need to create and store a key, which you then pass to ListenConf:

See: https://github.com/cretz/bine/blob/master/tor/listen.go#L56

Note:

// Key is the private key to use. If not present, a key is generated.

The lib you're using offers a function to do this.

See: https://github.com/cretz/bine/blob/b9d31d9c786616742e39a121b60522e803e96731/torutil/ed25519/ed25519.go#L132

Do this once and save privateKeyString:

keyPair, _ := ed25519.GenerateKey()
privateKeyString := hex.EncodeToString(keyPair.PrivateKey())

And then in your server code:

privateKeyBytes, _ := hex.DecodeString(privateKeyString)
privateKey := ed25519.PrivateKey(privateKeyBytes)
lc := &tor.ListenConf{
    Key: privateKey,
    Version3: true,
    RemotePorts: []int{80}
}

Answer 2

The process of creating the key, saving it, and passing it to ListenConf works perfectly.

Here is my modified code:

package main

import (
    "context"
    "encoding/hex"
    "encoding/json"
    "fmt"
    "github.com/cretz/bine/torutil/ed25519"
    "log"
    "net/http"
    "os"
    "sync"
    "time"

    "github.com/cretz/bine/tor"
)

func saveServiceInfo(key string) error {
    file, err := os.Create("serviceinfo.json")
    if err != nil {
        return err
    }
    defer file.Close()

    encoder := json.NewEncoder(file)
    return encoder.Encode(key)
}

func loadServiceInfo() (string, error) {
    file, err := os.Open("serviceinfo.json")
    if err != nil {
        return "", err
    }
    defer file.Close()
    decoder := json.NewDecoder(file)
    var key string
    if err := decoder.Decode(&key); err != nil {
        return "", err
    }
    return key, nil
}

func startHiddenService(privateKey ed25519.PrivateKey, wg *sync.WaitGroup) {
    defer wg.Done() // Decrement the WaitGroup counter when the goroutine completes
    fmt.Println("Starting the onion service, please wait a couple of minutes...")
    t, err := tor.Start(nil, &tor.StartConf{DataDir: "tor-data"})
    if err != nil {
        log.Panicf("Unable to start Tor: %v", err)
    }
    defer t.Close()

    listenCtx, listenCancel := context.WithTimeout(context.Background(), 3*time.Minute)
    defer listenCancel()

    onion, err := t.Listen(listenCtx, &tor.ListenConf{Version3: true, Key: privateKey, RemotePorts: []int{80}})
    if err != nil {
        log.Panicf("Unable to create onion service: %v", err)
    }
    defer onion.Close()

    fmt.Printf("Open Tor browser and navigate to http://%v.onion\n", onion.ID)
    fmt.Println("Press enter to exit")

    // Serve the current folder from HTTP
    errCh := make(chan error, 1)
    go func() {
        errCh <- http.Serve(onion, http.FileServer(http.Dir(".")))
    }()

    // End when enter is pressed
    go func() {
        fmt.Scanln()
        errCh <- nil
    }()

    // Wait for either an error or user input
    err = <-errCh
    if err != nil {
        log.Printf("Failed serving: %v", err)
    }
}

func main() {
    var privateKey string

    if _, err := os.Stat("serviceinfo.json"); err == nil {
        fmt.Println("Loading saved onion service...")

        // Load the service private key if the file exists
        privateKey, err = loadServiceInfo()
        if err != nil {
            log.Panicf("Failed to load service info: %v", err)
        }

        privateKeyBytes, _ := hex.DecodeString(privateKey)
        privateKey := ed25519.PrivateKey(privateKeyBytes)

        // Start hidden service with the stored private key
        var wg sync.WaitGroup
        wg.Add(1)
        go startHiddenService(privateKey, &wg)
        wg.Wait()

    } else {
        // Create a new onion service
        fmt.Println("Creating new onion service...")

        // Generate a new Ed25519 private key
        keyPair, _ := ed25519.GenerateKey(nil)
        privateKey = hex.EncodeToString(keyPair.PrivateKey())

        // Save the private key
        err = saveServiceInfo(privateKey)
        if err != nil {
            log.Panicf("Failed to save service info: %v", err)
        }

        // Start hidden service with the stored private key
        var wg sync.WaitGroup
        wg.Add(1)
        go startHiddenService(keyPair.PrivateKey(), &wg)
        wg.Wait()
    }
}