Added some NIP-42 functionality to the client (relay.go) (#38)

README.md

@@ -87,6 +87,46 @@ for _, url := range []string{"wss://nostr.zebedee.cloud", "wss://nostr-pub.wello
 }
 ```
 
+### Authenticating with NIP-42
+
+For this section, the user needs access to a relay implementing NIP-42.
+E.g., https://github.com/fiatjaf/relayer with a relay implementing the relayer.Auther interface.
+
+``` go
+func main() {
+	url := "ws://localhost:7447"
+
+	// Once the connection is initiated the server will send "AUTH" with the challenge string.
+	relay, err := nostr.RelayConnect(context.Background(), url)
+	if err != nil {
+		panic(err)
+	}
+
+	// Initialize test user.
+	sk := nostr.GeneratePrivateKey()
+	pub, _ := nostr.GetPublicKey(sk)
+	npub, _ := nip19.EncodePublicKey(pub)
+
+	// Relay.Challenges channel will receive the "AUTH" command.
+	challenge := <-relay.Challenges
+
+	// Create the auth event to send back.
+	// The user will be authenticated as pub.
+	event := nip42.CreateUnsignedAuthEvent(challenge, pub, url)
+	event.Sign(sk)
+
+	// Set-up context with 3 second time out.
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+	defer cancel()
+
+	// Send the event by calling relay.Auth.
+	// Returned status is either success, fail, or sent (if no reply given in the 3 second timeout).
+	auth_status := relay.Auth(ctx, event)
+
+	fmt.Printf("authenticated as %s: %s\n", npub, auth_status)
+}
+```
+
 ### Example script
 
 ```

example/example.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"io"
 	"os"
 	"strings"
 	"time"
@@ -13,7 +14,7 @@ import (
 )
 
 func main() {
-	ctx := context.Background()
+	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
 
 	// connect to relay
 	url := "wss://nostr.zebedee.cloud"
@@ -58,7 +59,7 @@ func main() {
 
 	go func() {
 		<-sub.EndOfStoredEvents
-		sub.Unsub()
+		cancel()
 	}()
 	for ev := range sub.Events {
 		evs = append(evs, ev)
@@ -106,19 +107,14 @@ func main() {
 	fmt.Fprintln(os.Stderr, "enter content of note, ending with an empty newline:")
 	for {
 		if n, err := reader.Read(b[:]); err == nil {
-			new_line := strings.TrimSpace(fmt.Sprintf("%s", b[:n]))
-			if new_line == "" {
-				break
-			} else if content == "" {
-				content = new_line
-			} else {
-				content = fmt.Sprintf("%s\n%s", content, new_line)
-			}
+			content = fmt.Sprintf("%s%s", content, fmt.Sprintf("%s", b[:n]))
+		} else if err == io.EOF {
+			break
 		} else {
 			panic(err)
 		}
 	}
-	ev.Content = content
+	ev.Content = strings.TrimSpace(content)
 	ev.Sign(sk)
 	for _, url := range []string{"wss://nostr.zebedee.cloud"} {
 		ctx := context.WithValue(context.Background(), "url", url)

nip42/nip42.go

@@ -7,6 +7,23 @@ import (
 	"github.com/nbd-wtf/go-nostr"
 )
 
+// CreateUnsignedAuthEvent creates an event which should be sent via an "AUTH" command.
+// If the authentication succeeds, the user will be authenticated as pubkey.
+func CreateUnsignedAuthEvent(challenge, pubkey, relayURL string) nostr.Event {
+	return nostr.Event{
+		PubKey:    pubkey,
+		CreatedAt: time.Now(),
+		Kind:      22242,
+		Tags: nostr.Tags{
+			nostr.Tag{"relay", relayURL},
+			nostr.Tag{"challenge", challenge},
+		},
+		Content: "",
+	}
+}
+
+// ValidateAuthEvent checks whether event is a valid NIP-42 event for given challenge and relayURL.
+// The result of the validation is encoded in the ok bool.
 func ValidateAuthEvent(event *nostr.Event, challenge string, relayURL string) (pubkey string, ok bool) {
 	if ok, _ := event.CheckSignature(); ok == false {
 		return "", false

relay.go

@@ -7,6 +7,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"log"
+	"sync"
 	"time"
 
 	s "github.com/SaveTheRbtz/generic-sync-map-go"
@@ -40,15 +41,16 @@ type Relay struct {
 	Connection    *Connection
 	subscriptions s.MapOf[string, *Subscription]
 
+	Challenges      chan string // NIP-42 Challenges
 	Notices         chan string
 	ConnectionError chan error
 
 	okCallbacks s.MapOf[string, func(bool)]
 }
 
-// RelayConnect returns a relay object connected to url
-// Once successfully connected, cancelling ctx has no effect 
-// To close the connection, call r.Close()
+// RelayConnect returns a relay object connected to url.
+// Once successfully connected, cancelling ctx has no effect.
+// To close the connection, call r.Close().
 func RelayConnect(ctx context.Context, url string) (*Relay, error) {
 	r := &Relay{URL: NormalizeURL(url)}
 	err := r.Connect(ctx)
@@ -80,6 +82,7 @@ func (r *Relay) Connect(ctx context.Context) error {
 		return fmt.Errorf("error opening websocket to '%s': %w", r.URL, err)
 	}
 
+	r.Challenges = make(chan string)
 	r.Notices = make(chan string)
 	r.ConnectionError = make(chan error)
 
@@ -121,6 +124,12 @@ func (r *Relay) Connect(ctx context.Context) error {
 				var content string
 				json.Unmarshal(jsonMessage[1], &content)
 				r.Notices <- content
+			case "AUTH":
+				var challenge string
+				json.Unmarshal(jsonMessage[1], &challenge)
+				go func() {
+					r.Challenges <- challenge
+				}()
 			case "EVENT":
 				if len(jsonMessage) < 3 {
 					continue
@@ -185,8 +194,8 @@ func (r *Relay) Connect(ctx context.Context) error {
 	return nil
 }
 
-// Publish sends an "EVENT" command to the relay r as in NIP-01
-// status can be: success, failed, or sent (no response from relay before ctx times out)
+// Publish sends an "EVENT" command to the relay r as in NIP-01.
+// Status can be: success, failed, or sent (no response from relay before ctx times out).
 func (r *Relay) Publish(ctx context.Context, event Event) Status {
 	status := PublishStatusFailed
 
@@ -242,9 +251,62 @@ func (r *Relay) Publish(ctx context.Context, event Event) Status {
 	}
 }
 
-// Subscribe sends a "REQ" command to the relay r as in NIP-01
-// Events are returned through the channel sub.Events
-// the subscription is closed when context ctx is cancelled ("CLOSE" in NIP-01)
+// Auth sends an "AUTH" command client -> relay as in NIP-42.
+// Status can be: success, failed, or sent (no response from relay before ctx times out).
+func (r *Relay) Auth(ctx context.Context, event Event) Status {
+	status := PublishStatusFailed
+
+	// data races on status variable without this mutex
+	var mu sync.Mutex
+
+	if _, ok := ctx.Deadline(); !ok {
+		// if no timeout is set, force it to 3 seconds
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithTimeout(ctx, 3*time.Second)
+		defer cancel()
+	}
+
+	// make it cancellable so we can stop everything upon receiving an "OK"
+	var cancel context.CancelFunc
+	ctx, cancel = context.WithCancel(ctx)
+	defer cancel()
+
+	// listen for an OK callback
+	okCallback := func(ok bool) {
+		mu.Lock()
+		if ok {
+			status = PublishStatusSucceeded
+		} else {
+			status = PublishStatusFailed
+		}
+		mu.Unlock()
+		cancel()
+	}
+	r.okCallbacks.Store(event.ID, okCallback)
+	defer r.okCallbacks.Delete(event.ID)
+
+	// send AUTH
+	if err := r.Connection.WriteJSON([]interface{}{"AUTH", event}); err != nil {
+		// status will be "failed"
+		return status
+	} else {
+		// use mu.Lock() just in case the okCallback got called, extremely unlikely.
+		mu.Lock()
+		status = PublishStatusSent
+		mu.Unlock()
+	}
+	// the context either times out, and the status is "sent"
+	// or the okCallback is called and the status is set to "succeeded" or "failed"
+	// NIP-42 does not mandate an "OK" reply to an "AUTH" message
+	<-ctx.Done()
+	mu.Lock()
+	defer mu.Unlock()
+	return status
+}
+
+// Subscribe sends a "REQ" command to the relay r as in NIP-01.
+// Events are returned through the channel sub.Events.
+// The subscription is closed when context ctx is cancelled ("CLOSE" in NIP-01).
 func (r *Relay) Subscribe(ctx context.Context, filters Filters) *Subscription {
 	if r.Connection == nil {
 		panic(fmt.Errorf("must call .Connect() first before calling .Subscribe()"))

subscription.go

@@ -24,8 +24,8 @@ type EventMessage struct {
 	Relay string
 }
 
-// Unsub closes the subscription, sending "CLOSE" to relay as in NIP-01
-// Unsub() also closes the channel sub.Events
+// Unsub closes the subscription, sending "CLOSE" to relay as in NIP-01.
+// Unsub() also closes the channel sub.Events.
 func (sub *Subscription) Unsub() {
 	sub.mutex.Lock()
 	defer sub.mutex.Unlock()
@@ -37,14 +37,14 @@ func (sub *Subscription) Unsub() {
 	sub.stopped = true
 }
 
-// Sub sets sub.Filters and then calls sub.Fire(ctx)
+// Sub sets sub.Filters and then calls sub.Fire(ctx).
 func (sub *Subscription) Sub(ctx context.Context, filters Filters) {
 	sub.Filters = filters
 	sub.Fire(ctx)
 }
 
-// Fire sends the "REQ" command to the relay
-// when ctx is cancelled, sub.Unsub() is called, closing the subscription
+// Fire sends the "REQ" command to the relay.
+// When ctx is cancelled, sub.Unsub() is called, closing the subscription.
 func (sub *Subscription) Fire(ctx context.Context) {
 	message := []interface{}{"REQ", sub.id}
 	for _, filter := range sub.Filters {