nip11: catch invalid/small urls.

nip11/fetch.go

@@ -16,20 +16,23 @@ import (
 // relay or if it doesn't have a NIP-11 handler -- although in that case it will also return
 // an error.
 func Fetch(ctx context.Context, u string) (info RelayInformationDocument, err error) {
-	if _, ok := ctx.Deadline(); !ok {
-		// if no timeout is set, force it to 7 seconds
-		var cancel context.CancelFunc
-		ctx, cancel = context.WithTimeout(ctx, 7*time.Second)
-		defer cancel()
-	}
-
 	// normalize URL to start with http://, https:// or without protocol
 	u = nostr.NormalizeURL(u)
+	if len(u) < 8 {
+		return info, fmt.Errorf("invalid url %s", u)
+	}
 
 	info = RelayInformationDocument{
 		URL: u,
 	}
 
+	if _, ok := ctx.Deadline(); !ok {
+		// if no timeout is set, force it to 7 seconds
+		var cancel context.CancelFunc
+		ctx, cancel = context.WithTimeout(ctx, 7*time.Second)
+		defer cancel()
+	}
+
 	// make request
 	req, err := http.NewRequestWithContext(ctx, "GET", "http"+u[2:], nil)