src/notification-server.c

/*
 * libwebsockets-test-server - libwebsockets test implementation
 *
 * Copyright (C) 2010-2011 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 <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <getopt.h>
#include <string.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/queue.h>
#include <fcntl.h>
#include <assert.h>
#include <pthread.h>
#include <libnetconf.h>
#include <libwebsockets.h>
#include "notification_module.h"
#include "mod_netconf.h"

#ifndef TEST_NOTIFICATION_SERVER
#include <httpd.h>
#include <http_log.h>
#include <apr_hash.h>
#include <apr_tables.h>

#else
static int force_exit = 0;
#endif

#if defined(TEST_NOTIFICATION_SERVER) || defined(WITH_NOTIFICATIONS)
static int max_poll_elements;

static struct pollfd *pollfds;
static int *fd_lookup;
static int count_pollfds;
static struct libwebsocket_context *context = NULL;
static server_rec *http_server = NULL;

struct ntf_thread_config {
	struct nc_session *session;
	char *session_hash;
};

extern apr_hash_t *netconf_sessions_list;
static pthread_key_t thread_key;

/*
 * This demo server shows how to use libwebsockets for one or more
 * websocket protocols in the same server
 *
 * It defines the following websocket protocols:
 *
 *  dumb-increment-protocol:  once the socket is opened, an incrementing
 *				ascii string is sent down it every 50ms.
 *				If you send "reset\n" on the websocket, then
 *				the incrementing number is reset to 0.
 *
 *  lws-mirror-protocol: copies any received packet to every connection also
 *				using this protocol, including the sender
 */

enum demo_protocols {
	/* always first */
	PROTOCOL_HTTP = 0,

	PROTOCOL_NOTIFICATION,

	/* always last */
	DEMO_PROTOCOL_COUNT
};


#define LOCAL_RESOURCE_PATH "."
char *resource_path = LOCAL_RESOURCE_PATH;

/*
 * We take a strict whitelist approach to stop ../ attacks
 */

struct serveable {
	const char *urlpath;
	const char *mimetype;
};

static const struct serveable whitelist[] = {
	{ "/favicon.ico", "image/x-icon" },
	{ "/libwebsockets.org-logo.png", "image/png" },

	/* last one is the default served if no match */
	{ "/test.html", "text/html" },
};

struct per_session_data__http {
	int fd;
};

/* this protocol server (always the first one) just knows how to do HTTP */

static int callback_http(struct libwebsocket_context *context,
		struct libwebsocket *wsi,
		enum libwebsocket_callback_reasons reason, void *user,
							   void *in, size_t len)
{
	char client_name[128];
	char client_ip[128];
	char buf[256];
	int n, m;
	unsigned char *p;
	static unsigned char buffer[4096];
	struct stat stat_buf;
	struct per_session_data__http *pss = (struct per_session_data__http *)user;
	int fd = (int)(long)in;

	switch (reason) {
	case LWS_CALLBACK_HTTP:

		/* check for the "send a big file by hand" example case */

		if (!strcmp((const char *)in, "/leaf.jpg")) {
			char leaf_path[1024];
			snprintf(leaf_path, sizeof(leaf_path), "%s/leaf.jpg", resource_path);

			/* well, let's demonstrate how to send the hard way */

			p = buffer;

			pss->fd = open(leaf_path, O_RDONLY);

			if (pss->fd < 0)
				return -1;

			fstat(pss->fd, &stat_buf);

			/*
			 * we will send a big jpeg file, but it could be
			 * anything.  Set the Content-Type: appropriately
			 * so the browser knows what to do with it.
			 */

			p += sprintf((char *)p,
				"HTTP/1.0 200 OK\x0d\x0a"
				"Server: libwebsockets\x0d\x0a"
				"Content-Type: image/jpeg\x0d\x0a"
					"Content-Length: %u\x0d\x0a\x0d\x0a",
					(unsigned int)stat_buf.st_size);

			/*
			 * send the http headers...
			 * this won't block since it's the first payload sent
			 * on the connection since it was established
			 * (too small for partial)
			 */

			n = libwebsocket_write(wsi, buffer,
				   p - buffer, LWS_WRITE_HTTP);

			if (n < 0) {
				close(pss->fd);
				return -1;
			}
			/*
			 * book us a LWS_CALLBACK_HTTP_WRITEABLE callback
			 */
			libwebsocket_callback_on_writable(context, wsi);
			break;
		}

		/* if not, send a file the easy way */

		for (n = 0; n < (sizeof(whitelist) / sizeof(whitelist[0]) - 1); n++)
			if (in && strcmp((const char *)in, whitelist[n].urlpath) == 0)
				break;

		sprintf(buf, "%s%s", resource_path, whitelist[n].urlpath);

		if (libwebsockets_serve_http_file(context, wsi, buf, whitelist[n].mimetype))
			return -1; /* through completion or error, close the socket */

		/*
		 * notice that the sending of the file completes asynchronously,
		 * we'll get a LWS_CALLBACK_HTTP_FILE_COMPLETION callback when
		 * it's done
		 */

		break;

	case LWS_CALLBACK_HTTP_FILE_COMPLETION:
//		lwsl_info("LWS_CALLBACK_HTTP_FILE_COMPLETION seen\n");
		/* kill the connection after we sent one file */
		return -1;

	case LWS_CALLBACK_HTTP_WRITEABLE:
		/*
		 * we can send more of whatever it is we were sending
		 */

		do {
			n = read(pss->fd, buffer, sizeof buffer);
			/* problem reading, close conn */
			if (n < 0)
				goto bail;
			/* sent it all, close conn */
			if (n == 0)
				goto bail;
			/*
			 * because it's HTTP and not websocket, don't need to take
			 * care about pre and postamble
			 */
			m = libwebsocket_write(wsi, buffer, n, LWS_WRITE_HTTP);
			if (m < 0)
				/* write failed, close conn */
				goto bail;
			if (m != n)
				/* partial write, adjust */
				lseek(pss->fd, m - n, SEEK_CUR);

		} while (!lws_send_pipe_choked(wsi));
		libwebsocket_callback_on_writable(context, wsi);
		break;

bail:
		close(pss->fd);
		return -1;

	/*
	 * callback for confirming to continue with client IP appear in
	 * protocol 0 callback since no websocket protocol has been agreed
	 * yet.  You can just ignore this if you won't filter on client IP
	 * since the default uhandled callback return is 0 meaning let the
	 * connection continue.
	 */

	case LWS_CALLBACK_FILTER_NETWORK_CONNECTION:
		libwebsockets_get_peer_addresses(context, wsi, (int)(long)in, client_name,
			     sizeof(client_name), client_ip, sizeof(client_ip));

		//fprintf(stderr, "Received network connect from %s (%s)\n", client_name, client_ip);
		/* if we returned non-zero from here, we kill the connection */
		break;

	/*
	 * callbacks for managing the external poll() array appear in
	 * protocol 0 callback
	 */

	case LWS_CALLBACK_ADD_POLL_FD:

		if (count_pollfds >= max_poll_elements) {
			lwsl_err("LWS_CALLBACK_ADD_POLL_FD: too many sockets to track\n");
			return 1;
		}

		fd_lookup[fd] = count_pollfds;
		pollfds[count_pollfds].fd = fd;
		pollfds[count_pollfds].events = (int)(long)len;
		pollfds[count_pollfds++].revents = 0;
		break;

	case LWS_CALLBACK_DEL_POLL_FD:
		if (!--count_pollfds)
			break;
		m = fd_lookup[fd];
		/* have the last guy take up the vacant slot */
		pollfds[m] = pollfds[count_pollfds];
		fd_lookup[pollfds[count_pollfds].fd] = m;
		break;

	case LWS_CALLBACK_SET_MODE_POLL_FD:
		pollfds[fd_lookup[fd]].events |= (int)(long)len;
		break;

	case LWS_CALLBACK_CLEAR_MODE_POLL_FD:
		pollfds[fd_lookup[fd]].events &= ~(int)(long)len;
		break;

	default:
		break;
	}

	return 0;
}

/**
 * this is just an example of parsing handshake headers, you don't need this
 * in your code unless you will filter allowing connections by the header
 * content
 */
//static void dump_handshake_info(struct libwebsocket *wsi)
//{
//	int n;
//	static const char *token_names[WSI_TOKEN_COUNT] = {
//		/*[WSI_TOKEN_GET_URI]		=*/ "GET URI",
//		/*[WSI_TOKEN_HOST]		=*/ "Host",
//		/*[WSI_TOKEN_CONNECTION]	=*/ "Connection",
//		/*[WSI_TOKEN_KEY1]		=*/ "key 1",
//		/*[WSI_TOKEN_KEY2]		=*/ "key 2",
//		/*[WSI_TOKEN_PROTOCOL]		=*/ "Protocol",
//		/*[WSI_TOKEN_UPGRADE]		=*/ "Upgrade",
//		/*[WSI_TOKEN_ORIGIN]		=*/ "Origin",
//		/*[WSI_TOKEN_DRAFT]		=*/ "Draft",
//		/*[WSI_TOKEN_CHALLENGE]		=*/ "Challenge",
//
//		/* new for 04 */
//		/*[WSI_TOKEN_KEY]		=*/ "Key",
//		/*[WSI_TOKEN_VERSION]		=*/ "Version",
//		/*[WSI_TOKEN_SWORIGIN]		=*/ "Sworigin",
//
//		/* new for 05 */
//		/*[WSI_TOKEN_EXTENSIONS]	=*/ "Extensions",
//
//		/* client receives these */
//		/*[WSI_TOKEN_ACCEPT]		=*/ "Accept",
//		/*[WSI_TOKEN_NONCE]		=*/ "Nonce",
//		/*[WSI_TOKEN_HTTP]		=*/ "Http",
//		/*[WSI_TOKEN_MUXURL]	=*/ "MuxURL",
//	};
//	char buf[256];
//
//	for (n = 0; n < WSI_TOKEN_COUNT; n++) {
//		if (!lws_hdr_total_length(wsi, n))
//			continue;
//
//		//lws_hdr_copy(wsi, buf, sizeof buf, n);
//
//		//fprintf(stderr, "    %s = %s\n", token_names[n], buf);
//	}
//}

/* dumb_increment protocol */

/*
 * one of these is auto-created for each connection and a pointer to the
 * appropriate instance is passed to the callback in the user parameter
 *
 * for this example protocol we use it to individualize the count for each
 * connection.
 */

struct per_session_data__notif_client {
	int number;
	char *session_key;
	struct nc_session *session;
};

struct session_with_mutex *get_ncsession_from_key(const char *session_key)
{
	struct session_with_mutex *locked_session = NULL;
	if (session_key == NULL) {
		return (NULL);
	}
	locked_session = (struct session_with_mutex *)apr_hash_get(netconf_sessions_list, session_key, APR_HASH_KEY_STRING);
	return locked_session;
}

/* rpc parameter is freed after the function call */
static int send_recv_process(struct nc_session *session, const char* operation, nc_rpc* rpc)
{
	nc_reply *reply = NULL;
	char *data = NULL;
	int ret = EXIT_SUCCESS;

	/* send the request and get the reply */
	switch (nc_session_send_recv(session, rpc, &reply)) {
	case NC_MSG_UNKNOWN:
		if (nc_session_get_status(session) != NC_SESSION_STATUS_WORKING) {
			#ifndef TEST_NOTIFICATION_SERVER
			if (http_server != NULL) {
				ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "notifications: receiving rpc-reply failed.");
			}
			#endif
			//cmd_disconnect(NULL);
			ret = EXIT_FAILURE;
			break;
		}
		#ifndef TEST_NOTIFICATION_SERVER
		if (http_server != NULL) {
			ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "notifications: Unknown error occurred.");
		}
		#endif
		ret = EXIT_FAILURE;
		break;
	case NC_MSG_NONE:
		/* error occurred, but processed by callback */
		break;
	case NC_MSG_REPLY:
		switch (nc_reply_get_type(reply)) {
		case NC_REPLY_OK:
			break;
		case NC_REPLY_DATA:
			#ifndef TEST_NOTIFICATION_SERVER
			if (http_server != NULL) {
				ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "notifications: recv: %s.", data = nc_reply_get_data (reply));
				free(data);
			}
			#endif
			break;
		case NC_REPLY_ERROR:
			/* wtf, you shouldn't be here !?!? */
			#ifndef TEST_NOTIFICATION_SERVER
			if (http_server != NULL) {
				ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "notifications: operation failed, but rpc-error was not processed.");
			}
			#endif
			ret = EXIT_FAILURE;
			break;
		default:
			#ifndef TEST_NOTIFICATION_SERVER
			if (http_server != NULL) {
				ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "notifications: unexpected operation result.");
			}
			#endif
			ret = EXIT_FAILURE;
			break;
		}
		break;
	default:
		#ifndef TEST_NOTIFICATION_SERVER
		if (http_server != NULL) {
			ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "notifications: Unknown error occurred.");
		}
		#endif
		ret = EXIT_FAILURE;
		break;
	}
	nc_rpc_free(rpc);
	nc_reply_free(reply);

	return (ret);
}

/**
 * \brief Callback to store incoming notification
 * \param [in] eventtime - time when notification occured
 * \param [in] content - content of notification
 */
static void notification_fileprint (time_t eventtime, const char* content)
{
	struct session_with_mutex *target_session = NULL;
	notification_t *ntf = NULL;
	char *session_hash = NULL;

	ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "Accepted notif: %lu %s\n", (unsigned long int) eventtime, content);

	session_hash = pthread_getspecific(thread_key);
	if (http_server != NULL) {
		ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "notification: fileprint getspecific (%s)", session_hash);
	}
	if (pthread_rwlock_wrlock(&session_lock) != 0) {
		#ifndef TEST_NOTIFICATION_SERVER
		ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "Error while locking rwlock");
		#endif
		return;
	}
	ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "Get session with mutex from key %s.", session_hash);
	target_session = get_ncsession_from_key(session_hash);
	if (target_session == NULL) {
		ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "no session found last_session_key (%s)", session_hash);
		if (pthread_rwlock_unlock (&session_lock) != 0) {
			ap_log_error (APLOG_MARK, APLOG_DEBUG, 0, http_server, "Error while unlocking rwlock");
			return;
		}
		return;
	}
	if (pthread_mutex_lock(&target_session->lock) != 0) {
		ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "Error while locking rwlock");
	}
	if (pthread_rwlock_unlock(&session_lock) != 0) {
		ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "Error while locking rwlock");
	}

	if (target_session->notifications == NULL) {
		ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "target_session->notifications is NULL");
		if (pthread_mutex_unlock(&target_session->lock) != 0) {
			ap_log_error (APLOG_MARK, APLOG_DEBUG, 0, http_server, "Error while unlocking rwlock: %d (%s)", errno, strerror(errno));
			return;
		}
		return;
	}
	if (http_server != NULL) {
		ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "notification: ready to push to notifications queue");
	}
	ntf = (notification_t *) apr_array_push(target_session->notifications);
	if (ntf == NULL) {
		ap_log_error (APLOG_MARK, APLOG_ERR, 0, http_server, "Failed to allocate element ");
		if (pthread_mutex_unlock(&target_session->lock) != 0) {
			ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "Error while unlocking rwlock");
			return;
		}
		return;
	}
	ntf->eventtime = eventtime;
	ntf->content = strdup(content);

	ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, http_server, "added notif to queue %u (%s)", (unsigned int) ntf->eventtime, "notifikace");

	if (pthread_mutex_unlock(&target_session->lock) != 0) {
		ap_log_error (APLOG_MARK, APLOG_DEBUG, 0, http_server, "Error while unlocking rwlock");
	}
}

/**
 * \brief Thread for libnetconf notifications dispatch
 * \param [in] arg - struct ntf_thread_config * with nc_session
 */
void* notification_thread(void* arg)
{
	struct ntf_thread_config *config = (struct ntf_thread_config*)arg;
	ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, http_server, "notifications: in thread for libnetconf notifications");

	/* store hash identification of netconf session for notifications printing callback */
	if (pthread_setspecific(thread_key, config->session_hash) != 0) {
		ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "notifications: cannot set thread-specific hash value.");
	}

	if (http_server != NULL) {
		ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "notifications: dispatching");
	}
	ncntf_dispatch_receive(config->session, notification_fileprint);
	ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, http_server, "notifications: ended thread for libnetconf notifications");
	//free(config);
	return (NULL);
}


int notif_subscribe(struct session_with_mutex *locked_session, const char *session_hash, time_t start_time, time_t stop_time)
{
	time_t start = -1;
	time_t stop = -1;
	struct nc_filter *filter = NULL;
	char *stream = NULL;
	nc_rpc *rpc = NULL;
	pthread_t thread;
	struct ntf_thread_config *tconfig;
	struct nc_session *session;

	ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "notif_subscribe");
	if (locked_session == NULL) {
		if (http_server != NULL) {
			ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "notifications: no locked_session was given.");
		}
		ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "Close notification client");
		return -1;
	}

	pthread_mutex_lock(&locked_session->lock);
	session = locked_session->session;

	start = time(NULL) + start_time;
	stop = time(NULL) + stop_time;
	if (http_server != NULL) { ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "notifications: history: %u %u", (unsigned int) start, (unsigned int) stop);
	}

	if (session == NULL) {
		ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "notifications: NETCONF session not established.");
		return -1;
	}

	/* check if notifications are allowed on this session */
	if (nc_session_notif_allowed(session) == 0) {
		ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "notifications: Notification subscription is not allowed on this session.");
		return -1;
	}
	/* check times */
	if (start != -1 && stop != -1 && start > stop) {
		ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "notifications: Subscription start time must be lower than the end time.");
		return -1;
	}

	ap_log_error (APLOG_MARK, APLOG_DEBUG, 0, http_server, "Prepare to execute subscription.");
	/* create requests */
	rpc = nc_rpc_subscribe(stream, filter, (start_time == 0)?NULL:&start, (stop_time == 0)?NULL:&stop);
	nc_filter_free(filter);
	if (rpc == NULL) {
		ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "notifications: creating an rpc request failed.");
		return -1;
	}

	ap_log_error (APLOG_MARK, APLOG_DEBUG, 0, http_server, "Send NC subscribe.");
	/** \todo replace with sth like netconf_op(http_server, session_hash, rpc) */
	if (send_recv_process(session, "subscribe", rpc) != 0) {
		ap_log_error (APLOG_MARK, APLOG_DEBUG, 0, http_server, "Subscription RPC failed.");
		return -1;
	}
	rpc = NULL; /* just note that rpc is already freed by send_recv_process() */
	locked_session->ntfc_subscribed = 1;

	ap_log_error (APLOG_MARK, APLOG_DEBUG, 0, http_server, "Create config for notification_thread.");
	tconfig = malloc(sizeof(struct ntf_thread_config));
	tconfig->session = session;
	tconfig->session_hash = strdup(session_hash);
	ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "notifications: creating libnetconf notification thread (%s).", tconfig->session_hash);

	pthread_mutex_unlock(&locked_session->lock);
	ap_log_error (APLOG_MARK, APLOG_DEBUG, 0, http_server, "Create notification_thread.");
	if (pthread_create(&thread, NULL, notification_thread, tconfig) != 0) {
		ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "notifications: creating a thread for receiving notifications failed");
		return -1;
	}
	pthread_detach(thread);
	ap_log_error (APLOG_MARK, APLOG_DEBUG, 0, http_server, "Subscription finished.");
	return 0;
}

static int callback_notification(struct libwebsocket_context *context,
			struct libwebsocket *wsi,
			enum libwebsocket_callback_reasons reason,
			void *user, void *in, size_t len)
{
	int n = 0;
	int m = 0;
	unsigned char buf[LWS_SEND_BUFFER_PRE_PADDING + 40960 + LWS_SEND_BUFFER_POST_PADDING];
	unsigned char *p = &buf[LWS_SEND_BUFFER_PRE_PADDING];
	struct per_session_data__notif_client *pss = (struct per_session_data__notif_client *)user;

	switch (reason) {
	case LWS_CALLBACK_ESTABLISHED:
		ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "notification client connected.");
		break;

	case LWS_CALLBACK_SERVER_WRITEABLE:
		if (pss->session_key == NULL) {
			return 0;
		}
		//ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "Callback server writeable.");
		//ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "lock session lock.");
		if (pthread_rwlock_wrlock (&session_lock) != 0) {
			ap_log_error (APLOG_MARK, APLOG_DEBUG, 0, http_server, "Error while unlocking rwlock: %d (%s)", errno, strerror(errno));
			return -1;
		}
		//ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "get session_with_mutex for %s.", pss->session_key);
		struct session_with_mutex *ls = get_ncsession_from_key(pss->session_key);
		if (ls == NULL) {
			if (http_server != NULL) {
				ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "notification: session not found");
			}
			if (pthread_rwlock_unlock (&session_lock) != 0) {
				ap_log_error (APLOG_MARK, APLOG_DEBUG, 0, http_server, "Error while unlocking rwlock: %d (%s)", errno, strerror(errno));
				return -1;
			}
			return -1;
		}
		pthread_mutex_lock(&ls->lock);
		if (pthread_rwlock_unlock (&session_lock) != 0) {
			ap_log_error (APLOG_MARK, APLOG_DEBUG, 0, http_server, "Error while unlocking rwlock: %d (%s)", errno, strerror(errno));
		}

		//ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "check for closed session.");
		if (ls->closed == 1) {
			ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "unlock session key.");
			if (pthread_rwlock_unlock (&session_lock) != 0) {
				ap_log_error (APLOG_MARK, APLOG_DEBUG, 0, http_server, "Error while unlocking unlock: %d (%s)", errno, strerror(errno));
				return -1;
			}
			return -1;
		}
		//ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "lock private lock.");
		notification_t *notif = NULL;
		//ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "check for uninitialized notification list.");
		if (ls->notifications == NULL) {
				ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "notification: no notifications array");
			ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "unlock private lock.");
			if (pthread_mutex_unlock(&ls->lock) != 0) {
				ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "notification: cannot unlock session");
			}
			return -1;
		}
		//ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "check for empty notification list.");
		if (!apr_is_empty_array(ls->notifications)) {
			ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "notification: POP notifications for session");

			while ((notif = (notification_t *) apr_array_pop(ls->notifications)) != NULL) {
				n = 0;
				json_object *notif_json = json_object_new_object();
				json_object_object_add(notif_json, "eventtime", json_object_new_int64(notif->eventtime));
				json_object_object_add(notif_json, "content", json_object_new_string(notif->content));

				const char *msgtext = json_object_to_json_string(notif_json);

				//n = sprintf((char *)p, "{\"eventtime\": \"%s\", \"content\": \"notification\"}", t);
				n = sprintf((char *)p, "%s", msgtext);
				ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "ws send %dB in %lu", n, sizeof(buf));
				m = libwebsocket_write(wsi, p, n, LWS_WRITE_TEXT);
				if (lws_send_pipe_choked(wsi)) {
					libwebsocket_callback_on_writable(context, wsi);
					break;
				}

				json_object_put(notif_json);
			}
			ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "notification: POP notifications done");
		}

		//ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "unlock private lock");
		if (pthread_mutex_unlock(&ls->lock) != 0) {
			ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "notification: cannot unlock session");
		}
		//ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "unlock session lock");

		if (m < n) {
			ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "ERROR %d writing to di socket.", n);

			return -1;
		}
		break;

	case LWS_CALLBACK_RECEIVE:
		ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "Callback receive.");
		ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, http_server, "received: (%s)", (char *)in);
		if (pss->session_key == NULL) {
			char session_key_buf[41];
			int start = -1;
			time_t stop = time(NULL) + 30;

			strncpy((char *) session_key_buf, (const char *) in, 40);
			session_key_buf[40] = '\0';
			pss->session_key = strdup(session_key_buf);
			sscanf(in+40, "%d %d", (int *) &start, (int *) &stop);
			ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, http_server, "notification: get key (%s) from (%s) (%i,%i)", pss->session_key, (char *) in, (int) start, (int) stop);

			ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "lock session lock");
			if (pthread_rwlock_rdlock (&session_lock) != 0) {
				ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "Error while locking rwlock: %d (%s)", errno, strerror(errno));
				return -1;
			}
			ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "get session from key (%s)", pss->session_key);
			struct session_with_mutex *ls = get_ncsession_from_key(pss->session_key);
			if (ls == NULL) {
				ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "notification: session_key not found (%s)", pss->session_key);
				ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "unlock session lock");
				if (pthread_rwlock_unlock (&session_lock) != 0) {
					ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "Error while unlocking rwlock: %d (%s)", errno, strerror(errno));
				}
				ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "Close notification client");
				return -1;
			}
			ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "lock private lock");
			pthread_mutex_lock(&ls->lock);

			ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "unlock session lock");
			if (pthread_rwlock_unlock (&session_lock) != 0) {
				ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "Error while unlocking rwlock: %d (%s)", errno, strerror(errno));
			}

			ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "Found session to subscribe notif.");
			if (ls->closed == 1) {
				ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, http_server, "session already closed - handle no notification");
				ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "unlock private lock");
				pthread_mutex_unlock(&ls->lock);
				ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "Close notification client");
				return -1;
			}
			if (ls->ntfc_subscribed != 0) {
				ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "notification: already subscribed");
				ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "unlock private lock");
				pthread_mutex_unlock(&ls->lock);
				/* do not close client, only do not subscribe again */
				return 0;
			}
			ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "notification: prepare to subscribe stream");
			ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "unlock session lock");
			pthread_mutex_unlock(&ls->lock);

			/* notif_subscribe locks on its own */
			return notif_subscribe(ls, pss->session_key, (time_t) start, (time_t) stop);
		}
		if (len < 6)
			break;
		break;
	/*
	 * this just demonstrates how to use the protocol filter. If you won't
	 * study and reject connections based on header content, you don't need
	 * to handle this callback
	 */

	case LWS_CALLBACK_FILTER_PROTOCOL_CONNECTION:
		//dump_handshake_info(wsi);
		/* you could return non-zero here and kill the connection */
		break;

	default:
		break;
	}

	return 0;
}

/* list of supported protocols and callbacks */

static struct libwebsocket_protocols protocols[] = {
	/* first protocol must always be HTTP handler */

	{
		"http-only",		/* name */
		callback_http,		/* callback */
		sizeof (struct per_session_data__http),	/* per_session_data_size */
		0,			/* max frame size / rx buffer */
	},
	{
		"notification-protocol",
		callback_notification,
		sizeof(struct per_session_data__notif_client),
		4000,
	},
	{ NULL, NULL, 0, 0 } /* terminator */
};


/**
 * initialization of notification module
 */
int notification_init(apr_pool_t * pool, server_rec * server)
{
	//char cert_path[1024];
	//char key_path[1024];
	//int use_ssl = 0;
	struct lws_context_creation_info info;
	int opts = 0;
	//char interface_name[128] = "";
	const char *iface = NULL;
	int debug_level = 7;

	memset(&info, 0, sizeof info);
	info.port = NOTIFICATION_SERVER_PORT;

	/* tell the library what debug level to emit and to send it to syslog */
	lws_set_log_level(debug_level, lwsl_emit_syslog);

	http_server = server;
	ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, http_server, "Initialization of libwebsocket");
	//lwsl_notice("libwebsockets test server - "
	//		"(C) Copyright 2010-2013 Andy Green <andy@warmcat.com> - "
	//					    "licensed under LGPL2.1\n");
	max_poll_elements = getdtablesize();
	pollfds = malloc(max_poll_elements * sizeof (struct pollfd));
	fd_lookup = malloc(max_poll_elements * sizeof (int));
	if (pollfds == NULL || fd_lookup == NULL) {
		ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "Out of memory pollfds=%d\n", max_poll_elements);
		return -1;
	}

	info.iface = iface;
	info.protocols = protocols;

	//snprintf(cert_path, sizeof(cert_path), "%s/libwebsockets-test-server.pem", resource_path);
	//snprintf(key_path, sizeof(cert_path), "%s/libwebsockets-test-server.key.pem", resource_path);

	//info.ssl_cert_filepath = cert_path;
	//info.ssl_private_key_filepath = key_path;

	info.gid = -1;
	info.uid = -1;
	info.options = opts;

	/* create server */
	context = libwebsocket_create_context(&info);
	if (context == NULL) {
		ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "libwebsocket init failed.");
		return -1;
	}

	ap_log_error(APLOG_MARK, APLOG_DEBUG, 0, http_server, "notifications: init of pthread_key_create.");
	if (pthread_key_create(&thread_key, NULL) != 0) {
		ap_log_error(APLOG_MARK, APLOG_ERR, 0, http_server, "notifications: pthread_key_create failed");
	}
	return 0;
}

void notification_close()
{
	libwebsocket_context_destroy(context);

	ap_log_error(APLOG_MARK, APLOG_NOTICE, 0, http_server, "libwebsockets-test-server exited cleanly\n");
}


/**
 * \brief send notification if any
 * \return < 0 on error
 */
int notification_handle()
{
	static struct timeval tv;
	static unsigned int olds = 0;
	int n = 0;

	gettimeofday(&tv, NULL);

	/*
	 * This provokes the LWS_CALLBACK_SERVER_WRITEABLE for every
	 * live websocket connection using the DUMB_INCREMENT protocol,
	 * as soon as it can take more packets (usually immediately)
	 */

	if (((unsigned int)tv.tv_sec - olds) > 0) {
		libwebsocket_callback_on_writable_all_protocol(&protocols[PROTOCOL_NOTIFICATION]);
		olds = tv.tv_sec;
	}


	/*
	 * this represents an existing server's single poll action
	 * which also includes libwebsocket sockets
	 */

	n = poll(pollfds, count_pollfds, 50);
	if (n < 0)
		return n;


	if (n) {
		for (n = 0; n < count_pollfds; n++) {
			if (pollfds[n].revents) {
				/*
				 * returns immediately if the fd does not
				 * match anything under libwebsockets
				 * control
				 */
				if (libwebsocket_service_fd(context, &pollfds[n]) < 0) {
					return 1;
				}
			}
		}
	}
	return 0;
}

#endif


#ifndef WITH_NOTIFICATIONS
#ifdef TEST_NOTIFICATION_SERVER
int main(int argc, char **argv)
{
	if (notification_init(NULL, NULL) == -1) {
		fprintf(stderr, "Error during initialization\n");
		return 1;
	}
	while (!force_exit) {
		notification_handle();
	}
	notification_close();
}
#endif
#endif