pmd: handle case we are already on drain list

Provide internal helper for adding to list that takes care of the
case we are already on the list.

https://github.com/warmcat/libwebsockets/issues/847

lib/client-parser.c

@@ -28,7 +28,6 @@
 
 int lws_client_rx_sm(struct lws *wsi, unsigned char c)
 {
-	struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
 	int callback_action = LWS_CALLBACK_CLIENT_RECEIVE;
 	int handled, n, m, rx_draining_ext = 0;
 	unsigned short close_code;
@@ -548,17 +547,14 @@ utf8_fail:			lwsl_info("utf8 error\n");
 		if (callback_action == LWS_CALLBACK_CLIENT_RECEIVE_PONG)
 			lwsl_info("Client doing pong callback\n");
 
-		if (n && eff_buf.token_len) {
+		if (n && eff_buf.token_len)
 			/* extension had more... main loop will come back
 			 * we want callback to be done with this set, if so,
 			 * because lws_is_final() hides it was final until the
 			 * last chunk
 			 */
-			wsi->u.ws.rx_draining_ext = 1;
+			lws_add_wsi_to_draining_ext_list(wsi);
-			wsi->u.ws.rx_draining_ext_list = pt->rx_draining_ext_list;
+		else
-			pt->rx_draining_ext_list = wsi;
-			lwsl_ext("%s: RX EXT DRAINING: Adding to list\n", __func__);
-		} else
 			lws_remove_wsi_from_draining_ext_list(wsi);
 
 		if (wsi->state == LWSS_RETURNED_CLOSE_ALREADY ||

lib/parsers.c

@@ -954,16 +954,39 @@ LWS_VISIBLE int lws_frame_is_binary(struct lws *wsi)
 {
 	return wsi->u.ws.frame_is_binary;
 }
+
+void
+lws_add_wsi_to_draining_ext_list(struct lws *wsi)
+{
+	struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
+
+	if (wsi->u.ws.rx_draining_ext)
+		return;
+
+	lwsl_ext("%s: RX EXT DRAINING: Adding to list\n", __func__);
+
+	wsi->u.ws.rx_draining_ext = 1;
+	wsi->u.ws.rx_draining_ext_list = pt->rx_draining_ext_list;
+	pt->rx_draining_ext_list = wsi;
+}
+
 void
 lws_remove_wsi_from_draining_ext_list(struct lws *wsi)
 {
 	struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
 	struct lws **w = &pt->rx_draining_ext_list;
 
+	if (!wsi->u.ws.rx_draining_ext)
+		return;
+
+	lwsl_ext("%s: RX EXT DRAINING: Removing from list\n", __func__);
+
 	wsi->u.ws.rx_draining_ext = 0;
+
 	/* remove us from context draining ext list */
 	while (*w) {
 		if (*w == wsi) {
+			/* if us, point it instead to who we were pointing to */
 			*w = wsi->u.ws.rx_draining_ext_list;
 			break;
 		}
@@ -980,7 +1003,6 @@ lws_remove_wsi_from_draining_ext_list(struct lws *wsi)
 int
 lws_rx_sm(struct lws *wsi, unsigned char c)
 {
-	struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
 	int callback_action = LWS_CALLBACK_RECEIVE;
 	int ret = 0, n, rx_draining_ext = 0;
 	struct lws_tokens eff_buf;
@@ -1446,10 +1468,7 @@ drain_extension:
 
 		if (n && eff_buf.token_len) {
 			/* extension had more... main loop will come back */
-			// lwsl_notice("ext has stuff to drain\n");
+			lws_add_wsi_to_draining_ext_list(wsi);
-			wsi->u.ws.rx_draining_ext = 1;
-			wsi->u.ws.rx_draining_ext_list = pt->rx_draining_ext_list;
-			pt->rx_draining_ext_list = wsi;
 		} else
 			lws_remove_wsi_from_draining_ext_list(wsi);
 

lib/private-libwebsockets.h

@@ -1990,6 +1990,8 @@ LWS_EXTERN int
 lws_plat_change_pollfd(struct lws_context *context, struct lws *wsi,
 		       struct lws_pollfd *pfd);
 LWS_EXTERN void
+lws_add_wsi_to_draining_ext_list(struct lws *wsi);
+LWS_EXTERN void
 lws_remove_wsi_from_draining_ext_list(struct lws *wsi);
 LWS_EXTERN int
 lws_plat_context_early_init(void);

lib/service.c

@@ -489,9 +489,10 @@ lws_service_flag_pending(struct lws_context *context, int tsi)
 	while (wsi) {
 		pt->fds[wsi->position_in_fds_table].revents |=
 			pt->fds[wsi->position_in_fds_table].events & LWS_POLLIN;
-		if (pt->fds[wsi->position_in_fds_table].revents &
+		if (pt->fds[wsi->position_in_fds_table].revents & LWS_POLLIN) {
-		    LWS_POLLIN)
 			forced = 1;
+			break;
+		}
 		wsi = wsi->u.ws.rx_draining_ext_list;
 	}