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  • /*
     * libwebsockets - small server side websockets and web server implementation
     *
    
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     * Copyright (C) 2010-2015 Andy Green <andy@warmcat.com>
    
     *
     *  This library is free software; you can redistribute it and/or
     *  modify it under the terms of the GNU Lesser General Public
     *  License as published by the Free Software Foundation:
     *  version 2.1 of the License.
     *
     *  This library is distributed in the hope that it will be useful,
     *  but WITHOUT ANY WARRANTY; without even the implied warranty of
     *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     *  Lesser General Public License for more details.
     *
     *  You should have received a copy of the GNU Lesser General Public
     *  License along with this library; if not, write to the Free Software
     *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
     *  MA  02110-1301  USA
     */
    
    #include "private-libwebsockets.h"
    
    
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    static int
    
    lws_calllback_as_writeable(struct lws *wsi)
    
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    {
    	int n;
    
    	switch (wsi->mode) {
    	case LWS_CONNMODE_WS_CLIENT:
    		n = LWS_CALLBACK_CLIENT_WRITEABLE;
    		break;
    	case LWS_CONNMODE_WS_SERVING:
    		n = LWS_CALLBACK_SERVER_WRITEABLE;
    		break;
    	default:
    		n = LWS_CALLBACK_HTTP_WRITEABLE;
    		break;
    	}
    	lwsl_info("%s: %p (user=%p)\n", __func__, wsi, wsi->user_space);
    
    	return user_callback_handle_rxflow(wsi->protocol->callback,
    
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    					   wsi, (enum lws_callback_reasons) n,
    					   wsi->user_space, NULL, 0);
    
    lws_handle_POLLOUT_event(struct lws *wsi, struct lws_pollfd *pollfd)
    
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    	int write_type = LWS_WRITE_PONG;
    
    	struct lws_tokens eff_buf;
    
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    #ifdef LWS_USE_HTTP2
    
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    #endif
    
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    	int ret, m, n;
    
    
    	/* pending truncated sends have uber priority */
    
    	if (wsi->truncated_send_len) {
    
    		if (lws_issue_raw(wsi, wsi->truncated_send_malloc +
    
    				wsi->truncated_send_offset,
    
    						wsi->truncated_send_len) < 0) {
    
    			lwsl_info("%s signalling to close\n", __func__);
    
    		/* leave POLLOUT active either way */
    		return 0;
    
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    	} else
    
    		if (wsi->state == WSI_STATE_FLUSHING_STORED_SEND_BEFORE_CLOSE)
    
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    			return -1; /* retry closing now */
    
    #ifdef LWS_USE_HTTP2
    
    	/* protocol packets are next */
    	if (wsi->pps) {
    
    		lwsl_info("servicing pps %d\n", wsi->pps);
    
    		switch (wsi->pps) {
    		case LWS_PPS_HTTP2_MY_SETTINGS:
    		case LWS_PPS_HTTP2_ACK_SETTINGS:
    
    			lws_http2_do_pps_send(lws_get_ctx(wsi), wsi);
    
    			break;
    		default:
    			break;
    		}
    		wsi->pps = LWS_PPS_NONE;
    
    		lws_rx_flow_control(wsi, 1);
    
    		return 0; /* leave POLLOUT active */
    	}
    
    	/* pending control packets have next priority */
    
    	if ((wsi->state == WSI_STATE_ESTABLISHED &&
    	     wsi->u.ws.ping_pending_flag) ||
    	    (wsi->state == WSI_STATE_RETURNED_CLOSE_ALREADY &&
    	     wsi->u.ws.payload_is_close)) {
    
    
    		if (wsi->u.ws.payload_is_close)
    			write_type = LWS_WRITE_CLOSE;
    
    
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    		n = lws_write(wsi, &wsi->u.ws.ping_payload_buf[
    
    					LWS_SEND_BUFFER_PRE_PADDING],
    
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    			      wsi->u.ws.ping_payload_len, write_type);
    
    		if (n < 0)
    			return -1;
    
    		/* well he is sent, mark him done */
    
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    		wsi->u.ws.ping_pending_flag = 0;
    
    		if (wsi->u.ws.payload_is_close)
    			/* oh... a close frame was it... then we are done */
    			return -1;
    
    		/* otherwise for PING, leave POLLOUT active either way */
    
    	/* if we are closing, don't confuse the user with writeable cb */
    
    	if (wsi->state == WSI_STATE_RETURNED_CLOSE_ALREADY)
    		goto user_service;
    
    	/* if nothing critical, user can get the callback */
    
    	m = lws_ext_callback_for_each_active(wsi, LWS_EXT_CALLBACK_IS_WRITEABLE,
    								       NULL, 0);
    #ifndef LWS_NO_EXTENSIONS
    
    	if (!wsi->extension_data_pending)
    
    		goto user_service;
    #endif
    	/*
    	 * check in on the active extensions, see if they
    	 * had pending stuff to spill... they need to get the
    	 * first look-in otherwise sequence will be disordered
    	 *
    	 * NULL, zero-length eff_buf means just spill pending
    	 */
    
    	ret = 1;
    	while (ret == 1) {
    
    		/* default to nobody has more to spill */
    
    		ret = 0;
    		eff_buf.token = NULL;
    		eff_buf.token_len = 0;
    
    		/* give every extension a chance to spill */
    
    		m = lws_ext_callback_for_each_active(wsi,
    					LWS_EXT_CALLBACK_PACKET_TX_PRESEND,
    							           &eff_buf, 0);
    		if (m < 0) {
    			lwsl_err("ext reports fatal error\n");
    			return -1;
    		}
    		if (m)
    			/*
    			 * at least one extension told us he has more
    			 * to spill, so we will go around again after
    			 */
    			ret = 1;
    
    		/* assuming they gave us something to send, send it */
    
    		if (eff_buf.token_len) {
    			n = lws_issue_raw(wsi, (unsigned char *)eff_buf.token,
    							     eff_buf.token_len);
    
    			if (n < 0) {
    				lwsl_info("closing from POLLOUT spill\n");
    
    			/*
    			 * Keep amount spilled small to minimize chance of this
    			 */
    			if (n != eff_buf.token_len) {
    				lwsl_err("Unable to spill ext %d vs %s\n",
    							  eff_buf.token_len, n);
    				return -1;
    			}
    		} else
    			continue;
    
    		/* no extension has more to spill */
    
    		if (!ret)
    			continue;
    
    		/*
    		 * There's more to spill from an extension, but we just sent
    		 * something... did that leave the pipe choked?
    		 */
    
    		if (!lws_send_pipe_choked(wsi))
    			/* no we could add more */
    			continue;
    
    		lwsl_info("choked in POLLOUT service\n");
    
    		/*
    		 * Yes, he's choked.  Leave the POLLOUT masked on so we will
    		 * come back here when he is unchoked.  Don't call the user
    		 * callback to enforce ordering of spilling, he'll get called
    		 * when we come back here and there's nothing more to spill.
    		 */
    
    		return 0;
    	}
    #ifndef LWS_NO_EXTENSIONS
    	wsi->extension_data_pending = 0;
    #endif
    
    	/* one shot */
    
    	if (pollfd) {
    
    		if (lws_change_pollfd(wsi, LWS_POLLOUT, 0)) {
    
    			lwsl_info("failed at set pollfd\n");
    
    		lws_libev_io(wsi, LWS_EV_STOP | LWS_EV_WRITE);
    
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    #ifdef LWS_USE_HTTP2
    
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    	 * we are the 'network wsi' for potentially many muxed child wsi with
    	 * no network connection of their own, who have to use us for all their
    	 * network actions.  So we use a round-robin scheme to share out the
    	 * POLLOUT notifications to our children.
    
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    	 * But because any child could exhaust the socket's ability to take
    	 * writes, we can only let one child get notified each time.
    
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    	 * In addition children may be closed / deleted / added between POLLOUT
    	 * notifications, so we can't hold pointers
    	 */
    
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    	if (wsi->mode != LWS_CONNMODE_HTTP2_SERVING) {
    		lwsl_info("%s: non http2\n", __func__);
    		goto notify;
    	}
    
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    	wsi->u.http2.requested_POLLOUT = 0;
    	if (!wsi->u.http2.initialized) {
    		lwsl_info("pollout on uninitialized http2 conn\n");
    		return 0;
    	}
    
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    	lwsl_info("%s: doing children\n", __func__);
    
    	wsi2 = wsi;
    	do {
    		wsi2 = wsi2->u.http2.next_child_wsi;
    		lwsl_info("%s: child %p\n", __func__, wsi2);
    		if (!wsi2)
    			continue;
    		if (!wsi2->u.http2.requested_POLLOUT)
    			continue;
    		wsi2->u.http2.requested_POLLOUT = 0;
    
    		if (lws_calllback_as_writeable(wsi2)) {
    
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    			lwsl_debug("Closing POLLOUT child\n");
    
    			lws_close_free_wsi(wsi2, LWS_CLOSE_STATUS_NOSTATUS);
    
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    		}
    		wsi2 = wsi;
    	} while (wsi2 != NULL && !lws_send_pipe_choked(wsi));
    
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    	lwsl_info("%s: completed\n", __func__);
    
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    	return 0;
    notify:
    #endif
    
    	return lws_calllback_as_writeable(wsi);
    
    lws_service_timeout_check(struct lws *wsi, unsigned int sec)
    
    {
    	/*
    	 * if extensions want in on it (eg, we are a mux parent)
    	 * give them a chance to service child timeouts
    	 */
    
    	if (lws_ext_callback_for_each_active(wsi, LWS_EXT_CALLBACK_1HZ,
    					     NULL, sec) < 0)
    
    		return 0;
    
    	if (!wsi->pending_timeout)
    		return 0;
    
    	/*
    	 * if we went beyond the allowed time, kill the
    	 * connection
    	 */
    
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    	if ((time_t)sec > wsi->pending_timeout_limit) {
    
    		lwsl_info("wsi %p: TIMEDOUT WAITING on %d\n",
    			  (void *)wsi, wsi->pending_timeout);
    
    		/*
    		 * Since he failed a timeout, he already had a chance to do
    		 * something and was unable to... that includes situations like
    		 * half closed connections.  So process this "failed timeout"
    		 * close as a violent death and don't try to do protocol
    		 * cleanup like flush partials.
    		 */
    		wsi->socket_is_permanently_unusable = 1;
    
    		lws_close_free_wsi(wsi, LWS_CLOSE_STATUS_NOSTATUS);
    
    
    int lws_rxflow_cache(struct lws *wsi, unsigned char *buf, int n, int len)
    
    {
    	/* his RX is flowcontrolled, don't send remaining now */
    	if (wsi->rxflow_buffer) {
    		/* rxflow while we were spilling prev rxflow */
    		lwsl_info("stalling in existing rxflow buf\n");
    		return 1;
    	}
    
    	/* a new rxflow, buffer it and warn caller */
    	lwsl_info("new rxflow input buffer len %d\n", len - n);
    
    	wsi->rxflow_buffer = lws_malloc(len - n);
    
    	wsi->rxflow_len = len - n;
    	wsi->rxflow_pos = 0;
    	memcpy(wsi->rxflow_buffer, buf + n, len - n);
    
    	return 0;
    }
    
    
     * lws_service_fd() - Service polled socket with something waiting
    
     * @context:	Websocket context
     * @pollfd:	The pollfd entry describing the socket fd and which events
     *		happened.
     *
     *	This function takes a pollfd that has POLLIN or POLLOUT activity and
     *	services it according to the state of the associated
    
     *
     *	The one call deals with all "service" that might happen on a socket
     *	including listen accepts, http files as well as websocket protocol.
     *
     *	If a pollfd says it has something, you can just pass it to
    
     *	lws_service_fd() whether it is a socket handled by lws or not.
    
     *	If it sees it is a lws socket, the traffic will be handled and
     *	pollfd->revents will be zeroed now.
     *
     *	If the socket is foreign to lws, it leaves revents alone.  So you can
     *	see if you should service yourself by checking the pollfd revents
     *	after letting lws try to service it.
     */
    
    LWS_VISIBLE int
    
    lws_service_fd(struct lws_context *context, struct lws_pollfd *pollfd)
    
    	int listen_socket_fds_index = 0;
    
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    	lws_sockfd_type our_fd = 0;
    
    	struct lws_tokens eff_buf;
    
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    	unsigned int pending = 0;
    
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    	char draining_flow = 0;
    	lws_sockfd_type mfd;
    	int timed_out = 0;
    	struct lws *wsi;
    	time_t now;
    	int n, m;
    	int more;
    
    	if (context->listen_service_fd)
    
    		listen_socket_fds_index = wsi_from_fd(context,
    			context->listen_service_fd)->position_in_fds_table;
    
    	 * you can call us with pollfd = NULL to just allow the once-per-second
    	 * global timeout checks; if less than a second since the last check
    	 * it returns immediately then.
    	 */
    
    	time(&now);
    
    	/* TODO: if using libev, we should probably use timeout watchers... */
    	if (context->last_timeout_check_s != now) {
    		context->last_timeout_check_s = now;
    
    		lws_plat_service_periodic(context);
    
    		/* global timeout check once per second */
    
    		if (pollfd)
    			our_fd = pollfd->fd;
    
    		for (n = 0; n < context->fds_count; n++) {
    
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    			mfd = context->fds[n].fd;
    			wsi = wsi_from_fd(context, mfd);
    
    			if (lws_service_timeout_check(wsi, (unsigned int)now))
    
    				/* he did time out... */
    
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    				if (mfd == our_fd)
    
    					/* it was the guy we came to service! */
    					timed_out = 1;
    
    					/* he's gone, no need to mark as handled */
    
    		}
    	}
    
    	/* the socket we came to service timed out, nothing to do */
    	if (timed_out)
    		return 0;
    
    	/* just here for timeout management? */
    
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    	if (!pollfd)
    
    		return 0;
    
    	/* no, here to service a socket descriptor */
    
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    	wsi = wsi_from_fd(context, pollfd->fd);
    
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    	if (!wsi)
    
    		/* not lws connection ... leave revents alone and return */
    		return 0;
    
    	/*
    	 * so that caller can tell we handled, past here we need to
    	 * zero down pollfd->revents after handling
    	 */
    
    
    	/*
    	 * deal with listen service piggybacking
    	 * every listen_service_modulo services of other fds, we
    	 * sneak one in to service the listen socket if there's anything waiting
    	 *
    	 * To handle connection storms, as found in ab, if we previously saw a
    	 * pending connection here, it causes us to check again next time.
    	 */
    
    	if (context->listen_service_fd && pollfd !=
    				       &context->fds[listen_socket_fds_index]) {
    		context->listen_service_count++;
    		if (context->listen_service_extraseen ||
    				context->listen_service_count ==
    					       context->listen_service_modulo) {
    			context->listen_service_count = 0;
    			m = 1;
    			if (context->listen_service_extraseen > 5)
    				m = 2;
    			while (m--) {
    				/*
    				 * even with extpoll, we prepared this
    				 * internal fds for listen
    				 */
    
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    				n = lws_poll_listen_fd(
    					&context->fds[listen_socket_fds_index]);
    
    				if (n > 0) { /* there's a conn waiting for us */
    
    					lws_service_fd(context,
    
    						&context->
    						  fds[listen_socket_fds_index]);
    					context->listen_service_extraseen++;
    				} else {
    					if (context->listen_service_extraseen)
    						context->
    						     listen_service_extraseen--;
    					break;
    				}
    			}
    		}
    
    	}
    
    	/* handle session socket closed */
    
    	if ((!(pollfd->revents & LWS_POLLIN)) &&
    			(pollfd->revents & LWS_POLLHUP)) {
    
    		lwsl_debug("Session Socket %p (fd=%d) dead\n",
    						       (void *)wsi, pollfd->fd);
    
    		goto close_and_handled;
    	}
    
    
    #ifdef _WIN32
    	if (pollfd->revents & LWS_POLLOUT)
    		wsi->sock_send_blocking = FALSE;
    #endif
    
    
    
    	/* okay, what we came here to do... */
    
    	switch (wsi->mode) {
    	case LWS_CONNMODE_HTTP_SERVING:
    	case LWS_CONNMODE_HTTP_SERVING_ACCEPTED:
    	case LWS_CONNMODE_SERVER_LISTENER:
    	case LWS_CONNMODE_SSL_ACK_PENDING:
    		n = lws_server_socket_service(context, wsi, pollfd);
    
    		if (n) /* closed by above */
    			return 1;
    
    		pending = lws_ssl_pending(wsi);
    		if (pending)
    			goto handle_pending;
    
    		goto handled;
    
    	case LWS_CONNMODE_WS_SERVING:
    	case LWS_CONNMODE_WS_CLIENT:
    
    	case LWS_CONNMODE_HTTP2_SERVING:
    
    
    		/* the guy requested a callback when it was OK to write */
    
    		if ((pollfd->revents & LWS_POLLOUT) &&
    
    		    (wsi->state == WSI_STATE_ESTABLISHED ||
    		     wsi->state == WSI_STATE_HTTP2_ESTABLISHED ||
    		     wsi->state == WSI_STATE_HTTP2_ESTABLISHED_PRE_SETTINGS ||
    
    		     wsi->state == WSI_STATE_RETURNED_CLOSE_ALREADY ||
    
    		     wsi->state == WSI_STATE_FLUSHING_STORED_SEND_BEFORE_CLOSE) &&
    
    			   lws_handle_POLLOUT_event(wsi, pollfd)) {
    
    			if (wsi->state == WSI_STATE_RETURNED_CLOSE_ALREADY)
    				wsi->state = WSI_STATE_FLUSHING_STORED_SEND_BEFORE_CLOSE;
    
    			lwsl_info("lws_service_fd: closing\n");
    
    		if (wsi->rxflow_buffer &&
    			      (wsi->rxflow_change_to & LWS_RXFLOW_ALLOW)) {
    
    			lwsl_info("draining rxflow\n");
    			/* well, drain it */
    
    			eff_buf.token = (char *)wsi->rxflow_buffer +
    						wsi->rxflow_pos;
    			eff_buf.token_len = wsi->rxflow_len - wsi->rxflow_pos;
    
    			draining_flow = 1;
    			goto drain;
    		}
    
    		/* any incoming data ready? */
    
    		if (!(pollfd->revents & LWS_POLLIN))
    			break;
    
    		eff_buf.token_len = lws_ssl_capable_read(wsi,
    
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    					context->service_buffer,
    					pending ? pending :
    					sizeof(context->service_buffer));
    
    		switch (eff_buf.token_len) {
    		case 0:
    			lwsl_info("service_fd: closing due to 0 length read\n");
    			goto close_and_handled;
    
    		case LWS_SSL_CAPABLE_MORE_SERVICE:
    			lwsl_info("SSL Capable more service\n");
    
    		case LWS_SSL_CAPABLE_ERROR:
    			lwsl_info("Closing when error\n");
    
    			goto close_and_handled;
    		}
    
    		/*
    		 * give any active extensions a chance to munge the buffer
    		 * before parse.  We pass in a pointer to an lws_tokens struct
    		 * prepared with the default buffer and content length that's in
    		 * there.  Rather than rewrite the default buffer, extensions
    		 * that expect to grow the buffer can adapt .token to
    		 * point to their own per-connection buffer in the extension
    		 * user allocation.  By default with no extensions or no
    		 * extension callback handling, just the normal input buffer is
    		 * used then so it is efficient.
    		 */
    
    		eff_buf.token = (char *)context->service_buffer;
    drain:
    
    		do {
    			more = 0;
    
    			m = lws_ext_callback_for_each_active(wsi,
    				LWS_EXT_CALLBACK_PACKET_RX_PREPARSE, &eff_buf, 0);
    			if (m < 0)
    				goto close_and_handled;
    			if (m)
    				more = 1;
    
    			/* service incoming data */
    
    			if (eff_buf.token_len) {
    
    				n = lws_read(wsi, (unsigned char *)eff_buf.token,
    					     eff_buf.token_len);
    
    				if (n < 0) {
    					/* we closed wsi */
    					n = 0;
    					goto handled;
    				}
    			}
    
    			eff_buf.token = NULL;
    			eff_buf.token_len = 0;
    		} while (more);
    
    
    		pending = lws_ssl_pending(wsi);
    		if (pending) {
    
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    			pending = pending > sizeof(context->service_buffer) ?
    				sizeof(context->service_buffer) : pending;
    
    		if (draining_flow && wsi->rxflow_buffer &&
    				 wsi->rxflow_pos == wsi->rxflow_len) {
    
    			lwsl_info("flow buffer: drained\n");
    
    			/* having drained the rxflow buffer, can rearm POLLIN */
    
    #ifdef LWS_NO_SERVER
    			n =
    #endif
    
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    			_lws_rx_flow_control(wsi);
    			/* n ignored, needed for NO_SERVER case */
    
    		}
    
    		break;
    
    	default:
    #ifdef LWS_NO_CLIENT
    		break;
    #else
    		n = lws_client_socket_service(context, wsi, pollfd);
    		goto handled;
    #endif
    	}
    
    	n = 0;
    	goto handled;
    
    close_and_handled:
    
    	lwsl_debug("Close and handled\n");
    
    	lws_close_free_wsi(wsi, LWS_CLOSE_STATUS_NOSTATUS);
    
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    	 * pollfd may point to something else after the close
    	 * due to pollfd swapping scheme on delete on some platforms
    	 * we can't clear revents now because it'd be the wrong guy's revents
    	 */
    
    
    handled:
    	pollfd->revents = 0;
    	return n;
    }
    
    /**
    
     * lws_service() - Service any pending websocket activity
    
     * @context:	Websocket context
     * @timeout_ms:	Timeout for poll; 0 means return immediately if nothing needed
     *		service otherwise block and service immediately, returning
     *		after the timeout if nothing needed service.
     *
     *	This function deals with any pending websocket traffic, for three
     *	kinds of event.  It handles these events on both server and client
     *	types of connection the same.
     *
     *	1) Accept new connections to our context's server
     *
     *	2) Call the receive callback for incoming frame data received by
     *	    server or client connections.
     *
     *	You need to call this service function periodically to all the above
     *	functions to happen; if your application is single-threaded you can
     *	just call it in your main event loop.
     *
     *	Alternatively you can fork a new process that asynchronously handles
     *	calling this service in a loop.  In that case you are happy if this
     *	call blocks your thread until it needs to take care of something and
     *	would call it with a large nonzero timeout.  Your loop then takes no
     *	CPU while there is nothing happening.
     *
     *	If you are calling it in a single-threaded app, you don't want it to
     *	wait around blocking other things in your loop from happening, so you
     *	would call it with a timeout_ms of 0, so it returns immediately if
     *	nothing is pending, or as soon as it services whatever was pending.
     */
    
    LWS_VISIBLE int
    
    lws_service(struct lws_context *context, int timeout_ms)
    
    {
    	return lws_plat_service(context, timeout_ms);
    }