service.c

/*
 * libwebsockets - small server side websockets and web server implementation
 *
 * Copyright (C) 2010-2018 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 "core/private.h"

int
lws_callback_as_writeable(struct lws *wsi)
{
	struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
	int n, m;

	lws_stats_atomic_bump(wsi->context, pt, LWSSTATS_C_WRITEABLE_CB, 1);
#if defined(LWS_WITH_STATS)
	if (wsi->active_writable_req_us) {
		uint64_t ul = lws_time_in_microseconds() -
			      wsi->active_writable_req_us;

		lws_stats_atomic_bump(wsi->context, pt,
				      LWSSTATS_MS_WRITABLE_DELAY, ul);
		lws_stats_atomic_max(wsi->context, pt,
				     LWSSTATS_MS_WORST_WRITABLE_DELAY, ul);
		wsi->active_writable_req_us = 0;
	}
#endif

	n = wsi->role_ops->writeable_cb[lwsi_role_server(wsi)];

	m = user_callback_handle_rxflow(wsi->protocol->callback,
					wsi, (enum lws_callback_reasons) n,
					wsi->user_space, NULL, 0);

	return m;
}

LWS_VISIBLE int
lws_handle_POLLOUT_event(struct lws *wsi, struct lws_pollfd *pollfd)
{
	volatile struct lws *vwsi = (volatile struct lws *)wsi;
	int n;

	//lwsl_notice("%s: %p\n", __func__, wsi);

	vwsi->leave_pollout_active = 0;
	vwsi->handling_pollout = 1;
	/*
	 * if another thread wants POLLOUT on us, from here on while
	 * handling_pollout is set, he will only set leave_pollout_active.
	 * If we are going to disable POLLOUT, we will check that first.
	 */
	wsi->could_have_pending = 0; /* clear back-to-back write detection */

	/*
	 * user callback is lowest priority to get these notifications
	 * actually, since other pending things cannot be disordered
	 *
	 * Priority 1: pending truncated sends are incomplete ws fragments
	 *	       If anything else sent first the protocol would be
	 *	       corrupted.
	 *
	 *	       These are post- any compression transform
	 */

	if (lws_has_buffered_out(wsi)) {
		//lwsl_notice("%s: completing partial\n", __func__);
		if (lws_issue_raw(wsi, NULL, 0) < 0) {
			lwsl_info("%s signalling to close\n", __func__);
			goto bail_die;
		}
		/* leave POLLOUT active either way */
		goto bail_ok;
	} else
		if (lwsi_state(wsi) == LRS_FLUSHING_BEFORE_CLOSE) {
			wsi->socket_is_permanently_unusable = 1;
			goto bail_die; /* retry closing now */
		}

	/* Priority 2: pre- compression transform */

#if defined(LWS_WITH_HTTP_STREAM_COMPRESSION)
	if (wsi->http.comp_ctx.buflist_comp ||
	    wsi->http.comp_ctx.may_have_more) {
		enum lws_write_protocol wp = LWS_WRITE_HTTP;

		lwsl_info("%s: completing comp partial (buflist_comp %p, may %d)\n",
				__func__, wsi->http.comp_ctx.buflist_comp,
				wsi->http.comp_ctx.may_have_more
				);

		if (wsi->role_ops->write_role_protocol(wsi, NULL, 0, &wp) < 0) {
			lwsl_info("%s signalling to close\n", __func__);
			goto bail_die;
		}
		lws_callback_on_writable(wsi);

		goto bail_ok;
	}
#endif

#ifdef LWS_WITH_CGI
	/*
	 * A cgi master's wire protocol remains h1 or h2.  He is just getting
	 * his data from his child cgis.
	 */
	if (wsi->http.cgi) {
		/* also one shot */
		if (pollfd)
			if (lws_change_pollfd(wsi, LWS_POLLOUT, 0)) {
				lwsl_info("failed at set pollfd\n");
				return 1;
			}
		goto user_service_go_again;
	}
#endif

	/* if we got here, we should have wire protocol ops set on the wsi */
	assert(wsi->role_ops);

	if (!wsi->role_ops->handle_POLLOUT)
		goto bail_ok;

	switch ((wsi->role_ops->handle_POLLOUT)(wsi)) {
	case LWS_HP_RET_BAIL_OK:
		goto bail_ok;
	case LWS_HP_RET_BAIL_DIE:
		goto bail_die;
	case LWS_HP_RET_USER_SERVICE:
		break;
	default:
		assert(0);
	}

	/* one shot */

	if (pollfd) {
		int eff = vwsi->leave_pollout_active;

		if (!eff) {
			if (lws_change_pollfd(wsi, LWS_POLLOUT, 0)) {
				lwsl_info("failed at set pollfd\n");
				goto bail_die;
			}
		}

		vwsi->handling_pollout = 0;

		/* cannot get leave_pollout_active set after the above */
		if (!eff && wsi->leave_pollout_active) {
			/*
			 * got set inbetween sampling eff and clearing
			 * handling_pollout, force POLLOUT on
			 */
			lwsl_debug("leave_pollout_active\n");
			if (lws_change_pollfd(wsi, 0, LWS_POLLOUT)) {
				lwsl_info("failed at set pollfd\n");
				goto bail_die;
			}
		}

		vwsi->leave_pollout_active = 0;
	}

	if (lwsi_role_client(wsi) &&
	    !wsi->hdr_parsing_completed &&
	     lwsi_state(wsi) != LRS_H2_WAITING_TO_SEND_HEADERS &&
	     lwsi_state(wsi) != LRS_ISSUE_HTTP_BODY
	     )
		goto bail_ok;


#ifdef LWS_WITH_CGI
user_service_go_again:
#endif

	if (wsi->role_ops->perform_user_POLLOUT) {
		if (wsi->role_ops->perform_user_POLLOUT(wsi) == -1)
			goto bail_die;
		else
			goto bail_ok;
	}
	
	lwsl_debug("%s: %p: non mux: wsistate 0x%x, ops %s\n", __func__, wsi,
		   wsi->wsistate, wsi->role_ops->name);

	vwsi = (volatile struct lws *)wsi;
	vwsi->leave_pollout_active = 0;

	n = lws_callback_as_writeable(wsi);
	vwsi->handling_pollout = 0;

	if (vwsi->leave_pollout_active)
		lws_change_pollfd(wsi, 0, LWS_POLLOUT);

	return n;

	/*
	 * since these don't disable the POLLOUT, they are always doing the
	 * right thing for leave_pollout_active whether it was set or not.
	 */

bail_ok:
	vwsi->handling_pollout = 0;
	vwsi->leave_pollout_active = 0;

	return 0;

bail_die:
	vwsi->handling_pollout = 0;
	vwsi->leave_pollout_active = 0;

	return -1;
}

static int
__lws_service_timeout_check(struct lws *wsi, time_t sec)
{
	struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
#if defined(LWS_ROLE_H1) || defined(LWS_ROLE_H2)
	int n = 0;
#endif

	(void)n;

	/*
	 * if we went beyond the allowed time, kill the
	 * connection
	 */
	if (wsi->dll_timeout.prev &&
	    lws_compare_time_t(wsi->context, sec, wsi->pending_timeout_set) >
			       wsi->pending_timeout_limit) {

#if defined(LWS_ROLE_H1) || defined(LWS_ROLE_H2)
		if (wsi->desc.sockfd != LWS_SOCK_INVALID &&
		    wsi->position_in_fds_table >= 0)
			n = pt->fds[wsi->position_in_fds_table].events;
#endif

		lws_stats_atomic_bump(wsi->context, pt, LWSSTATS_C_TIMEOUTS, 1);

		/* no need to log normal idle keepalive timeout */
		if (wsi->pending_timeout != PENDING_TIMEOUT_HTTP_KEEPALIVE_IDLE)
#if defined(LWS_ROLE_H1) || defined(LWS_ROLE_H2)
			lwsl_info("wsi %p: TIMEDOUT WAITING on %d "
				  "(did hdr %d, ah %p, wl %d, pfd "
				  "events %d) %llu vs %llu\n",
				  (void *)wsi, wsi->pending_timeout,
				  wsi->hdr_parsing_completed, wsi->http.ah,
				  pt->http.ah_wait_list_length, n,
				  (unsigned long long)sec,
				  (unsigned long long)wsi->pending_timeout_limit);
#if defined(LWS_WITH_CGI)
		if (wsi->http.cgi)
			lwsl_notice("CGI timeout: %s\n", wsi->http.cgi->summary);
#endif
#else
		lwsl_info("wsi %p: TIMEDOUT WAITING on %d ", (void *)wsi,
			  wsi->pending_timeout);
#endif

		/*
		 * 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;
		if (lwsi_state(wsi) == LRS_WAITING_SSL && wsi->protocol)
			wsi->protocol->callback(wsi,
				LWS_CALLBACK_CLIENT_CONNECTION_ERROR,
				wsi->user_space,
				(void *)"Timed out waiting SSL", 21);

		__lws_close_free_wsi(wsi, LWS_CLOSE_STATUS_NOSTATUS, "timeout");

		return 1;
	}

	return 0;
}

int lws_rxflow_cache(struct lws *wsi, unsigned char *buf, int n, int len)
{
	struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
	uint8_t *buffered;
	size_t blen;
	int ret = 0, m;

	/* his RX is flowcontrolled, don't send remaining now */
	blen = lws_buflist_next_segment_len(&wsi->buflist, &buffered);
	if (blen) {
		if (buf >= buffered && buf + len <= buffered + blen) {
			/* rxflow while we were spilling prev rxflow */
			lwsl_info("%s: staying in rxflow buf\n", __func__);

			return 1;
		}
		ret = 1;
	}

	/* a new rxflow, buffer it and warn caller */

	m = lws_buflist_append_segment(&wsi->buflist, buf + n, len - n);

	if (m < 0)
		return -1;
	if (m) {
		lwsl_debug("%s: added %p to rxflow list\n", __func__, wsi);
		lws_dll_lws_add_front(&wsi->dll_buflist, &pt->dll_head_buflist);
	}

	return ret;
}

/* this is used by the platform service code to stop us waiting for network
 * activity in poll() when we have something that already needs service
 */

LWS_VISIBLE LWS_EXTERN int
lws_service_adjust_timeout(struct lws_context *context, int timeout_ms, int tsi)
{
	struct lws_context_per_thread *pt = &context->pt[tsi];

	/*
	 * Figure out if we really want to wait in poll()... we only need to
	 * wait if really nothing already to do and we have to wait for
	 * something from network
	 */
#if defined(LWS_ROLE_WS) && !defined(LWS_WITHOUT_EXTENSIONS)
	/* 1) if we know we are draining rx ext, do not wait in poll */
	if (pt->ws.rx_draining_ext_list)
		return 0;
#endif

	/* 2) if we know we have non-network pending data,
	 *    do not wait in poll */

	if (pt->context->tls_ops &&
	    pt->context->tls_ops->fake_POLLIN_for_buffered &&
	    pt->context->tls_ops->fake_POLLIN_for_buffered(pt))
			return 0;

	/*
	 * 3) If there is any wsi with rxflow buffered and in a state to process
	 *    it, we should not wait in poll
	 */

	lws_start_foreach_dll(struct lws_dll_lws *, d,
			      pt->dll_head_buflist.next) {
		struct lws *wsi = lws_container_of(d, struct lws, dll_buflist);

		if (lwsi_state(wsi) != LRS_DEFERRING_ACTION)
			return 0;

	/*
	 * 4) If any guys with http compression to spill, we shouldn't wait in
	 *    poll but hurry along and service them
	 */

	} lws_end_foreach_dll(d);

	return timeout_ms;
}

/*
 * POLLIN said there is something... we must read it, and either use it; or
 * if other material already in the buflist append it and return the buflist
 * head material.
 */
int
lws_buflist_aware_read(struct lws_context_per_thread *pt, struct lws *wsi,
		       struct lws_tokens *ebuf)
{
	int n, prior = (int)lws_buflist_next_segment_len(&wsi->buflist, NULL);

	ebuf->token = (char *)pt->serv_buf;
	ebuf->len = lws_ssl_capable_read(wsi, pt->serv_buf,
					 wsi->context->pt_serv_buf_size);

	if (ebuf->len == LWS_SSL_CAPABLE_MORE_SERVICE && prior)
		goto get_from_buflist;

	if (ebuf->len <= 0)
		return 0;

	/* nothing in buflist already?  Then just use what we read */

	if (!prior)
		return 0;

	/* stash what we read */

	n = lws_buflist_append_segment(&wsi->buflist, (uint8_t *)ebuf->token,
				       ebuf->len);
	if (n < 0)
		return -1;
	if (n) {
		lwsl_debug("%s: added %p to rxflow list\n", __func__, wsi);
		lws_dll_lws_add_front(&wsi->dll_buflist, &pt->dll_head_buflist);
	}

	/* get the first buflist guy in line */

get_from_buflist:

	ebuf->len = (int)lws_buflist_next_segment_len(&wsi->buflist,
						      (uint8_t **)&ebuf->token);

	return 1; /* came from buflist */
}

int
lws_buflist_aware_consume(struct lws *wsi, struct lws_tokens *ebuf, int used,
			  int buffered)
{
	struct lws_context_per_thread *pt = &wsi->context->pt[(int)wsi->tsi];
	int m;

	/* it's in the buflist; we didn't use any */

	if (!used && buffered)
		return 0;

	if (used && buffered) {
		m = lws_buflist_use_segment(&wsi->buflist, used);
		lwsl_info("%s: draining rxflow: used %d, next %d\n",
			    __func__, used, m);
		if (m)
			return 0;

		lwsl_info("%s: removed %p from dll_buflist\n", __func__, wsi);
		lws_dll_lws_remove(&wsi->dll_buflist);

		return 0;
	}

	/* any remainder goes on the buflist */

	if (used != ebuf->len) {
		m = lws_buflist_append_segment(&wsi->buflist,
					       (uint8_t *)ebuf->token + used,
					       ebuf->len - used);
		if (m < 0)
			return 1; /* OOM */
		if (m) {
			lwsl_debug("%s: added %p to rxflow list\n",
				   __func__, wsi);
			lws_dll_lws_add_front(&wsi->dll_buflist,
					      &pt->dll_head_buflist);
		}
	}

	return 0;
}

void
lws_service_do_ripe_rxflow(struct lws_context_per_thread *pt)
{
	struct lws_pollfd pfd;

	if (!pt->dll_head_buflist.next)
		return;

	/*
	 * service all guys with pending rxflow that reached a state they can
	 * accept the pending data
	 */

	lws_pt_lock(pt, __func__);

	lws_start_foreach_dll_safe(struct lws_dll_lws *, d, d1,
				   pt->dll_head_buflist.next) {
		struct lws *wsi = lws_container_of(d, struct lws, dll_buflist);

		pfd.events = LWS_POLLIN;
		pfd.revents = LWS_POLLIN;
		pfd.fd = -1;

		lwsl_debug("%s: rxflow processing: %p 0x%x\n", __func__, wsi,
			    wsi->wsistate);

		if (!lws_is_flowcontrolled(wsi) &&
		    lwsi_state(wsi) != LRS_DEFERRING_ACTION &&
		    (wsi->role_ops->handle_POLLIN)(pt, wsi, &pfd) ==
						   LWS_HPI_RET_PLEASE_CLOSE_ME)
			lws_close_free_wsi(wsi, LWS_CLOSE_STATUS_NOSTATUS,
					   "close_and_handled");

	} lws_end_foreach_dll_safe(d, d1);

	lws_pt_unlock(pt);
}

/*
 * guys that need POLLIN service again without waiting for network action
 * can force POLLIN here if not flowcontrolled, so they will get service.
 *
 * Return nonzero if anybody got their POLLIN faked
 */
int
lws_service_flag_pending(struct lws_context *context, int tsi)
{
	struct lws_context_per_thread *pt = &context->pt[tsi];
	int forced = 0;

	lws_pt_lock(pt, __func__);

	/*
	 * 1) If there is any wsi with a buflist and in a state to process
	 *    it, we should not wait in poll
	 */

	lws_start_foreach_dll(struct lws_dll_lws *, d, pt->dll_head_buflist.next) {
		struct lws *wsi = lws_container_of(d, struct lws, dll_buflist);

		if (lwsi_state(wsi) != LRS_DEFERRING_ACTION) {
			forced = 1;
			break;
		}
	} lws_end_foreach_dll(d);

#if defined(LWS_ROLE_WS)
	forced |= role_ops_ws.service_flag_pending(context, tsi);
#endif

#if defined(LWS_WITH_TLS)
	/*
	 * 2) For all guys with buffered SSL read data already saved up, if they
	 * are not flowcontrolled, fake their POLLIN status so they'll get
	 * service to use up the buffered incoming data, even though their
	 * network socket may have nothing
	 */
	lws_start_foreach_dll_safe(struct lws_dll_lws *, p, p1,
				   pt->tls.pending_tls_head.next) {
		struct lws *wsi = lws_container_of(p, struct lws,
						   tls.pending_tls_list);

		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 & LWS_POLLIN) {
			forced = 1;
			/*
			 * he's going to get serviced now, take him off the
			 * list of guys with buffered SSL.  If he still has some
			 * at the end of the service, he'll get put back on the
			 * list then.
			 */
			__lws_ssl_remove_wsi_from_buffered_list(wsi);
		}

	} lws_end_foreach_dll_safe(p, p1);
#endif

	lws_pt_unlock(pt);

	return forced;
}

static int
lws_service_periodic_checks(struct lws_context *context,
			    struct lws_pollfd *pollfd, int tsi)
{
	struct lws_context_per_thread *pt = &context->pt[tsi];
	struct lws_timed_vh_protocol *tmr;
	lws_sockfd_type our_fd = 0, tmp_fd;
	struct lws *wsi;
	int timed_out = 0;
	time_t now;
#if defined(LWS_ROLE_H1) || defined(LWS_ROLE_H2)
	struct allocated_headers *ah;
	int n, m;
#endif

	if (!context->protocol_init_done)
		if (lws_protocol_init(context)) {
			lwsl_err("%s: lws_protocol_init failed\n", __func__);
			return -1;
		}

	time(&now);

	/*
	 * handle case that system time was uninitialized when lws started
	 * at boot, and got initialized a little later
	 */
	if (context->time_up < 1464083026 && now > 1464083026)
		context->time_up = now;

	if (context->last_timeout_check_s &&
	    now - context->last_timeout_check_s > 100) {
		/*
		 * There has been a discontiguity.  Any stored time that is
		 * less than context->time_discontiguity should have context->
		 * time_fixup added to it.
		 *
		 * Some platforms with no RTC will experience this as a normal
		 * event when ntp sets their clock, but we can have started
		 * long before that with a 0-based unix time.
		 */

		context->time_discontiguity = now;
		context->time_fixup = now - context->last_timeout_check_s;

		lwsl_notice("time discontiguity: at old time %llus, "
			    "new time %llus: +%llus\n",
			    (unsigned long long)context->last_timeout_check_s,
			    (unsigned long long)context->time_discontiguity,
			    (unsigned long long)context->time_fixup);

		context->last_timeout_check_s = now - 1;
	}

	if (!lws_compare_time_t(context, context->last_timeout_check_s, now))
		return 0;

	context->last_timeout_check_s = now;

#if defined(LWS_WITH_STATS)
	if (!tsi && now - context->last_dump > 10) {
		lws_stats_log_dump(context);
		context->last_dump = now;
	}
#endif

	lws_plat_service_periodic(context);
	lws_check_deferred_free(context, tsi, 0);

#if defined(LWS_WITH_PEER_LIMITS)
	lws_peer_cull_peer_wait_list(context);
#endif

	/* retire unused deprecated context */
#if !defined(LWS_PLAT_OPTEE) && !defined(LWS_WITH_ESP32)
#if !defined(_WIN32)
	if (context->deprecated && !context->count_wsi_allocated) {
		lwsl_notice("%s: ending deprecated context\n", __func__);
		kill(getpid(), SIGINT);
		return 0;
	}
#endif
#endif
	/* global timeout check once per second */

	if (pollfd)
		our_fd = pollfd->fd;

	/*
	 * Phase 1: check every wsi on our pt's timeout check list
	 */

	lws_pt_lock(pt, __func__);

	lws_start_foreach_dll_safe(struct lws_dll_lws *, d, d1,
				   context->pt[tsi].dll_head_timeout.next) {
		wsi = lws_container_of(d, struct lws, dll_timeout);
		tmp_fd = wsi->desc.sockfd;
		if (__lws_service_timeout_check(wsi, now)) {
			/* he did time out... */
			if (tmp_fd == our_fd)
				/* it was the guy we came to service! */
				timed_out = 1;
			/* he's gone, no need to mark as handled */
		}
	} lws_end_foreach_dll_safe(d, d1);

#if defined(LWS_ROLE_H1) || defined(LWS_ROLE_H2)
	/*
	 * Phase 2: double-check active ah timeouts independent of wsi
	 *	    timeout status
	 */

	ah = pt->http.ah_list;
	while (ah) {
		int len;
		char buf[256];
		const unsigned char *c;

		if (!ah->in_use || !ah->wsi || !ah->assigned ||
		    (ah->wsi->vhost &&
		     lws_compare_time_t(context, now, ah->assigned) <
		     ah->wsi->vhost->timeout_secs_ah_idle + 360)) {
			ah = ah->next;
			continue;
		}

		/*
		 * a single ah session somehow got held for
		 * an unreasonable amount of time.
		 *
		 * Dump info on the connection...
		 */
		wsi = ah->wsi;
		buf[0] = '\0';
#if !defined(LWS_PLAT_OPTEE)
		lws_get_peer_simple(wsi, buf, sizeof(buf));
#else
		buf[0] = '\0';
#endif
		lwsl_notice("ah excessive hold: wsi %p\n"
			    "  peer address: %s\n"
			    "  ah pos %u\n",
			    wsi, buf, ah->pos);
		buf[0] = '\0';
		m = 0;
		do {
			c = lws_token_to_string(m);
			if (!c)
				break;
			if (!(*c))
				break;

			len = lws_hdr_total_length(wsi, m);
			if (!len || len > (int)sizeof(buf) - 1) {
				m++;
				continue;
			}

			if (lws_hdr_copy(wsi, buf, sizeof buf, m) > 0) {
				buf[sizeof(buf) - 1] = '\0';

				lwsl_notice("   %s = %s\n",
					    (const char *)c, buf);
			}
			m++;
		} while (1);

		/* explicitly detach the ah */
		lws_header_table_detach(wsi, 0);

		/* ... and then drop the connection */

		m = 0;
		if (wsi->desc.sockfd == our_fd) {
			m = timed_out;

			/* it was the guy we came to service! */
			timed_out = 1;
		}

		if (!m) /* if he didn't already timeout */
			__lws_close_free_wsi(wsi, LWS_CLOSE_STATUS_NOSTATUS,
					     "excessive ah");

		ah = pt->http.ah_list;
	}
#endif
	lws_pt_unlock(pt);

#if 0
	{
		char s[300], *p = s;

		for (n = 0; n < context->count_threads; n++)
			p += sprintf(p, " %7lu (%5d), ",
				     context->pt[n].count_conns,
				     context->pt[n].fds_count);

		lwsl_notice("load: %s\n", s);
	}
#endif
	/*
	 * Phase 3: vhost / protocol timer callbacks
	 */

	/* 3a: lock, collect, and remove vh timers that are pending */

	lws_context_lock(context, "expired vh timers"); /* context ---------- */

	n = 0;

	/*
	 * first, under the context lock, get a count of the number of
	 * expired timers so we can allocate for them (or not, cleanly)
	 */

	lws_start_foreach_ll(struct lws_vhost *, v, context->vhost_list) {

		if (v->timed_vh_protocol_list) {

			lws_start_foreach_ll_safe(struct lws_timed_vh_protocol *,
					q, v->timed_vh_protocol_list, next) {
				if (now >= q->time && q->tsi_req == tsi)
					n++;
			} lws_end_foreach_ll_safe(q);
		}

	} lws_end_foreach_ll(v, vhost_next);

	/* if nothing to do, unlock and move on to the next vhost */

	if (!n) {
		lws_context_unlock(context); /* ----------- context */
		goto vh_timers_done;
	}

	/*
	 * attempt to do the wsi and timer info allocation
	 * first en bloc.  If it fails, we can just skip the rest and
	 * the timers will still be pending next time.
	 */

	wsi = lws_zalloc(sizeof(*wsi), "cbwsi");
	if (!wsi) {
		/*
		 * at this point, we haven't cleared any vhost
		 * timers.  We can fail out and retry cleanly
		 * next periodic check
		 */
		lws_context_unlock(context); /* ----------- context */
		goto vh_timers_done;
	}
	wsi->context = context;

	tmr = lws_zalloc(sizeof(*tmr) * n, "cbtmr");
	if (!tmr) {
		/* again OOM here can be handled cleanly */
		lws_free(wsi);
		lws_context_unlock(context); /* ----------- context */
		goto vh_timers_done;
	}

	/* so we have the allocation for n pending timers... */

	m = 0;
	lws_start_foreach_ll(struct lws_vhost *, v, context->vhost_list) {

		if (v->timed_vh_protocol_list) {

			lws_vhost_lock(v); /* vhost ------------------------- */

			lws_start_foreach_ll_safe(struct lws_timed_vh_protocol *,
					q, v->timed_vh_protocol_list, next) {

				/* only do n */
				if (m == n)
					break;

				if (now >= q->time && q->tsi_req == tsi) {

					/*
					 * tmr is an allocated array.
					 * Ignore the linked-list.
					 */
					tmr[m].vhost = v;
					tmr[m].protocol = q->protocol;
					tmr[m++].reason = q->reason;

					/* take the timer out now we took
					 * responsibility */
					__lws_timed_callback_remove(v, q);
				}

			} lws_end_foreach_ll_safe(q);

			lws_vhost_unlock(v); /* ----------------------- vhost */
		}

	} lws_end_foreach_ll(v, vhost_next);
	lws_context_unlock(context); /* ---------------------------- context */

	/* 3b: call the vh timer callbacks outside any lock */

	for (m = 0; m < n; m++) {

		wsi->vhost = tmr[m].vhost; /* not a real bound wsi */
		wsi->protocol = tmr[m].protocol;

		lwsl_debug("%s: timed cb: vh %s, protocol %s, reason %d\n",
			   __func__, tmr[m].vhost->name, tmr[m].protocol->name,
			   tmr[m].reason);
		tmr[m].protocol->callback(wsi, tmr[m].reason, NULL, NULL, 0);
	}

	lws_free(tmr);
	lws_free(wsi);

vh_timers_done:

	/*
	 * Phase 4: check for unconfigured vhosts due to required
	 *	    interface missing before
	 */

	lws_context_lock(context, "periodic checks");
	lws_start_foreach_llp(struct lws_vhost **, pv,
			      context->no_listener_vhost_list) {
		struct lws_vhost *v = *pv;
		lwsl_debug("deferred iface: checking if on vh %s\n", (*pv)->name);
		if (_lws_vhost_init_server(NULL, *pv) == 0) {
			/* became happy */
			lwsl_notice("vh %s: became connected\n", v->name);
			*pv = v->no_listener_vhost_list;
			v->no_listener_vhost_list = NULL;
			break;
		}
	} lws_end_foreach_llp(pv, no_listener_vhost_list);
	lws_context_unlock(context);

	/*
	 * Phase 5: role periodic checks
	 */
#if defined(LWS_ROLE_WS)
	role_ops_ws.periodic_checks(context, tsi, now);
#endif
#if defined(LWS_ROLE_CGI)
	role_ops_cgi.periodic_checks(context, tsi, now);
#endif

	/*
	 * Phase 6: check the remaining cert lifetime daily
	 */

	if (context->tls_ops &&
	    context->tls_ops->periodic_housekeeping)
		context->tls_ops->periodic_housekeeping(context, now);

	return 0;
}

LWS_VISIBLE int
lws_service_fd_tsi(struct lws_context *context, struct lws_pollfd *pollfd,
		   int tsi)
{
	struct lws_context_per_thread *pt = &context->pt[tsi];
	struct lws *wsi;

	if (!context || context->being_destroyed1)
		return -1;

	/* the case there's no pollfd to service, we just want to do periodic */
	if (!pollfd) {
		lws_service_periodic_checks(context, pollfd, tsi);
		return -2;
	}

	/* no, here to service a socket descriptor */
	wsi = wsi_from_fd(context, pollfd->fd);
	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
	 */

	/* handle session socket closed */

	if ((!(pollfd->revents & pollfd->events & LWS_POLLIN)) &&
	    (pollfd->revents & LWS_POLLHUP)) {
		wsi->socket_is_permanently_unusable = 1;
		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

	if ((!(pollfd->revents & pollfd->events & LWS_POLLIN)) &&
	    (pollfd->revents & LWS_POLLHUP)) {
		lwsl_debug("pollhup\n");
		wsi->socket_is_permanently_unusable = 1;
		goto close_and_handled;
	}

#if defined(LWS_WITH_TLS)
	if (lwsi_state(wsi) == LRS_SHUTDOWN &&
	    lws_is_ssl(wsi) && wsi->tls.ssl) {
		switch (__lws_tls_shutdown(wsi)) {
		case LWS_SSL_CAPABLE_DONE:
		case LWS_SSL_CAPABLE_ERROR:
			goto close_and_handled;

		case LWS_SSL_CAPABLE_MORE_SERVICE_READ:
		case LWS_SSL_CAPABLE_MORE_SERVICE_WRITE:
		case LWS_SSL_CAPABLE_MORE_SERVICE:
			goto handled;
		}
	}