From 60359110d71bee29fda496b792fe9ec538a01683 Mon Sep 17 00:00:00 2001
From: fiatjaf <fiatjaf@gmail.com>
Date: Tue, 6 Feb 2024 00:45:36 -0300
Subject: [PATCH] nip46: client.

---
 nip46/client.go | 180 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 180 insertions(+)
 create mode 100644 nip46/client.go

diff --git a/nip46/client.go b/nip46/client.go
new file mode 100644
index 0000000..f40dbf2
--- /dev/null
+++ b/nip46/client.go
@@ -0,0 +1,180 @@
+package nip46
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/url"
+	"strconv"
+	"sync/atomic"
+
+	"github.com/mailru/easyjson"
+	"github.com/nbd-wtf/go-nostr"
+	"github.com/nbd-wtf/go-nostr/nip04"
+	"github.com/puzpuzpuz/xsync/v3"
+)
+
+type BunkerClient struct {
+	serial          atomic.Uint64
+	clientSecretKey string
+	pool            *nostr.SimplePool
+	target          string
+	relays          []string
+	sharedSecret    []byte
+	listeners       *xsync.MapOf[string, chan Response]
+
+	// memoized
+	getPublicKeyResponse string
+}
+
+// ConnectBunker establishes an RPC connection to a NIP-46 signer using the relays and secret provided in the bunkerURL.
+// pool can be passed to reuse an existing pool, otherwise a new pool will be created.
+func ConnectBunker(
+	ctx context.Context,
+	clientSecretKey string,
+	bunkerURL string,
+	pool *nostr.SimplePool,
+) (*BunkerClient, error) {
+	parsed, err := url.Parse(bunkerURL)
+	if err != nil {
+		return nil, fmt.Errorf("invalid url: %w", err)
+	}
+
+	if parsed.Scheme != "bunker" {
+		return nil, fmt.Errorf("wrong scheme '%s', must be bunker://", parsed.Scheme)
+	}
+
+	target := parsed.Host
+	if !nostr.IsValidPublicKey(target) {
+		return nil, fmt.Errorf("'%s' is not a valid public key hex", target)
+	}
+
+	secret := parsed.Query().Get("secret")
+	relays := parsed.Query()["relay"]
+
+	if pool == nil {
+		pool = nostr.NewSimplePool(ctx)
+	}
+
+	shared, err := nip04.ComputeSharedSecret(target, clientSecretKey)
+	if err != nil {
+		return nil, fmt.Errorf("failed to compute shared secret: %w", err)
+	}
+
+	clientPubKey, _ := nostr.GetPublicKey(clientSecretKey)
+	bunker := &BunkerClient{
+		clientSecretKey: clientSecretKey,
+		pool:            pool,
+		target:          target,
+		relays:          relays,
+		sharedSecret:    shared,
+		listeners:       xsync.NewMapOf[string, chan Response](),
+	}
+
+	go func() {
+		events := pool.SubMany(ctx, relays, nostr.Filters{
+			{
+				Tags:  nostr.TagMap{"p": []string{clientPubKey}},
+				Kinds: []int{nostr.KindNostrConnect},
+			},
+		})
+		for ie := range events {
+			if ie.Kind != nostr.KindNostrConnect {
+				continue
+			}
+
+			var resp Response
+			plain, err := nip04.Decrypt(ie.Content, shared)
+			if err != nil {
+				continue
+			}
+
+			err = json.Unmarshal([]byte(plain), &resp)
+			if err != nil {
+				continue
+			}
+
+			if dispatcher, ok := bunker.listeners.Load(resp.ID); ok {
+				dispatcher <- resp
+			}
+		}
+	}()
+
+	ourPubkey, _ := nostr.GetPublicKey(clientSecretKey)
+	_, err = bunker.RPC(ctx, "connect", []string{ourPubkey, secret})
+	return bunker, err
+}
+
+func (bunker *BunkerClient) Ping(ctx context.Context) error {
+	_, err := bunker.RPC(ctx, "ping", []string{})
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (bunker *BunkerClient) GetPublicKey(ctx context.Context) (string, error) {
+	if bunker.getPublicKeyResponse != "" {
+		return bunker.getPublicKeyResponse, nil
+	}
+	resp, err := bunker.RPC(ctx, "get_public_key", []string{})
+	bunker.getPublicKeyResponse = resp
+	return resp, err
+}
+
+func (bunker *BunkerClient) SignEvent(ctx context.Context, evt *nostr.Event) error {
+	resp, err := bunker.RPC(ctx, "sign_event", []string{evt.String()})
+	if err == nil {
+		err = easyjson.Unmarshal([]byte(resp), evt)
+	}
+	return err
+}
+
+func (bunker *BunkerClient) RPC(ctx context.Context, method string, params []string) (string, error) {
+	id := strconv.FormatUint(bunker.serial.Add(1), 10)
+	req, err := json.Marshal(Request{
+		ID:     id,
+		Method: method,
+		Params: params,
+	})
+	if err != nil {
+		return "", err
+	}
+
+	content, err := nip04.Encrypt(string(req), bunker.sharedSecret)
+	if err != nil {
+		return "", fmt.Errorf("error encrypting request: %w", err)
+	}
+
+	evt := nostr.Event{
+		Content:   content,
+		CreatedAt: nostr.Now(),
+		Kind:      nostr.KindNostrConnect,
+		Tags:      nostr.Tags{{"p", bunker.target}},
+	}
+	if err := evt.Sign(bunker.clientSecretKey); err != nil {
+		return "", fmt.Errorf("failed to sign request event: %w", err)
+	}
+
+	respWaiter := make(chan Response)
+	bunker.listeners.Store(id, respWaiter)
+
+	hasWorked := false
+	for _, r := range bunker.relays {
+		relay, err := bunker.pool.EnsureRelay(r)
+		if err == nil {
+			hasWorked = true
+		}
+		relay.Publish(ctx, evt)
+	}
+	if !hasWorked {
+		return "", fmt.Errorf("couldn't connect to any relay")
+	}
+
+	resp := <-respWaiter
+	if resp.Error != "" {
+		return "", fmt.Errorf("response error: %s", resp.Error)
+	}
+
+	return resp.Result, nil
+}