support performing AUTH in the middle of SimplePool's subMany*

pool.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"log"
+	"strings"
 	"sync"
 	"time"
 
@@ -18,7 +19,8 @@ type SimplePool struct {
 	Relays  *xsync.MapOf[string, *Relay]
 	Context context.Context
 
-	cancel context.CancelFunc
+	authHandler func(*Event) error
+	cancel      context.CancelFunc
 }
 
 type IncomingEvent struct {
@@ -26,17 +28,40 @@ type IncomingEvent struct {
 	Relay *Relay
 }
 
-func NewSimplePool(ctx context.Context) *SimplePool {
+type PoolOption interface {
+	IsPoolOption()
+	Apply(*SimplePool)
+}
+
+func NewSimplePool(ctx context.Context, opts ...PoolOption) *SimplePool {
 	ctx, cancel := context.WithCancel(ctx)
 
-	return &SimplePool{
+	pool := &SimplePool{
 		Relays: xsync.NewMapOf[*Relay](),
 
 		Context: ctx,
 		cancel:  cancel,
 	}
+
+	for _, opt := range opts {
+		opt.Apply(pool)
+	}
+
+	return pool
 }
 
+// WithAuthHandler must be a function that signs the auth event when called.
+// it will be called whenever any relay in the pool returns a `CLOSED` message
+// with the "auth-required:" prefix, only once for each relay
+type WithAuthHandler func(authEvent *Event) error
+
+func (_ WithAuthHandler) IsPoolOption() {}
+func (h WithAuthHandler) Apply(pool *SimplePool) {
+	pool.authHandler = h
+}
+
+var _ PoolOption = (WithAuthHandler)(nil)
+
 func (pool *SimplePool) EnsureRelay(url string) (*Relay, error) {
 	nm := NormalizeURL(url)
 
@@ -91,6 +116,7 @@ func (pool *SimplePool) subMany(ctx context.Context, urls []string, filters Filt
 				cancel()
 			}()
 
+			hasAuthed := false
 			interval := 3 * time.Second
 			for {
 				select {
@@ -105,7 +131,9 @@ func (pool *SimplePool) subMany(ctx context.Context, urls []string, filters Filt
 				if err != nil {
 					goto reconnect
 				}
+				hasAuthed = false
 
+			subscribe:
 				sub, err = relay.Subscribe(ctx, filters)
 				if err != nil {
 					goto reconnect
@@ -149,7 +177,15 @@ func (pool *SimplePool) subMany(ctx context.Context, urls []string, filters Filt
 							})
 						}
 					case reason := <-sub.ClosedReason:
-						log.Printf("CLOSED from %s: '%s'\n", nm, reason)
+						if strings.HasPrefix(reason, "auth-required:") && pool.authHandler != nil && !hasAuthed {
+							// relay is requesting auth. if we can we will perform auth and try again
+							if err := relay.Auth(ctx, pool.authHandler); err == nil {
+								hasAuthed = true // so we don't keep doing AUTH again and again
+								goto subscribe
+							}
+						} else {
+							log.Printf("CLOSED from %s: '%s'\n", nm, reason)
+						}
 						return
 					case <-ctx.Done():
 						return
@@ -202,6 +238,9 @@ func (pool *SimplePool) subManyEose(ctx context.Context, urls []string, filters
 				return
 			}
 
+			hasAuthed := false
+
+		subscribe:
 			sub, err := relay.Subscribe(ctx, filters)
 			if sub == nil {
 				debugLogf("error subscribing to %s with %v: %s", relay, filters, err)
@@ -215,7 +254,15 @@ func (pool *SimplePool) subManyEose(ctx context.Context, urls []string, filters
 				case <-sub.EndOfStoredEvents:
 					return
 				case reason := <-sub.ClosedReason:
-					log.Printf("CLOSED from %s: '%s'\n", nm, reason)
+					if strings.HasPrefix(reason, "auth-required:") && pool.authHandler != nil && !hasAuthed {
+						// relay is requesting auth. if we can we will perform auth and try again
+						if err := relay.Auth(ctx, pool.authHandler); err == nil {
+							hasAuthed = true // so we don't keep doing AUTH again and again
+							goto subscribe
+						}
+					} else {
+						log.Printf("CLOSED from %s: '%s'\n", nm, reason)
+					}
 					return
 				case evt, more := <-sub.Events:
 					if !more {