QUIC: added stateless reset support. The new "quic_stateless_reset_token_key" directive is added. It sets the endpoint key used to generate stateless reset tokens and enables feature. If the endpoint receives short-header packet that can't be matched to existing connection, a stateless reset packet is generated with a proper token. If a valid stateless reset token is found in the incoming packet, the connection is closed. Example configuration: http { quic_stateless_reset_token_key "foo"; ... }

--- a/src/event/ngx_event_quic_protection.h
+++ b/src/event/ngx_event_quic_protection.h
@@ -39,6 +39,8 @@ int ngx_quic_set_encryption_secret(ngx_p
 
 ngx_int_t ngx_quic_key_update(ngx_connection_t *c,
     ngx_quic_secrets_t *current, ngx_quic_secrets_t *next);
+ngx_int_t ngx_quic_new_sr_token(ngx_connection_t *c, ngx_str_t *cid,
+    ngx_str_t *key, u_char *token);
 
 ngx_int_t ngx_quic_encrypt(ngx_quic_header_t *pkt, ngx_ssl_conn_t *ssl_conn,
      ngx_str_t *res);