SSL: support for TLSv1.3 early data with BoringSSL. Early data AKA 0-RTT mode is enabled as long as "ssl_early_data on" is specified in the configuration (default is off). The $ssl_early_data variable evaluates to "1" if the SSL handshake isn't yet completed, and can be used to set the Early-Data header as per draft-ietf-httpbis-replay-04.

--- a/src/http/modules/ngx_http_ssl_module.h
+++ b/src/http/modules/ngx_http_ssl_module.h
@@ -20,6 +20,7 @@ typedef struct {
     ngx_ssl_t                       ssl;
 
     ngx_flag_t                      prefer_server_ciphers;
+    ngx_flag_t                      early_data;
 
     ngx_uint_t                      protocols;