finit/event.c

/* Event aggregator, also serves as event cache, remembering GW and IFUP states
 *
 * Copyright (c) 2015  Joachim Nilsson <troglobit@gmail.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "config.h"		/* Generated by configure script */
#include "libite/lite.h"

#include "finit.h"
#include "service.h"

struct ifc {
	LIST_ENTRY(ifc) link;

	int  updown;
	char ifname[IFNAMSIZ];
};

static int              gwup    = 0;
static LIST_HEAD(, ifc) ifcache = LIST_HEAD_INITIALIZER();


static int cache_gw(char *updown)
{
	int oldgw = gwup;

	if (!strncasecmp(updown, "UP", 2))
		gwup = 1;
	else
		gwup = 0;

	return (oldgw == gwup) ? 0 : gwup == 0 ? -1 : 1;
}

static struct ifc *find_if(char *ifname)
{
	struct ifc *entry;

	LIST_FOREACH(entry, &ifcache, link) {
		if (!strncmp(entry->ifname, ifname, sizeof(entry->ifname)))
			return entry;
	}

	return NULL;
}

static int alloc_if(char *ifname, int updown)
{
	struct ifc *entry = calloc(1, sizeof(struct ifc));

	if (!entry) {
		_pe("Failed recording interface event");
		return 0;
	}

	_d("Creating new node for %s", ifname);
	entry->updown = updown;
	strlcpy(entry->ifname, ifname, sizeof(entry->ifname));
	LIST_INSERT_HEAD(&ifcache, entry, link);

	return 1;
}

static int free_if(char *ifname)
{
	struct ifc *entry = find_if(ifname);

	if (!entry)
		return 0;

	LIST_REMOVE(entry, link);
	return -1;
}

static int cache_if(char *ifname, int updown)
{
	struct ifc *entry = find_if(ifname);

	if (entry) {
		int old = entry->updown;
		
		entry->updown = updown;
		return old == updown ? 0 : updown ? 1 : -1;
	}

	return alloc_if(ifname, updown);
}

/*
 * System events like GW/IF are cached, this function caters to that
 * Returns: 0 if no change, -1 on condition low, +1 on condition high
 */
static int event_cache(char *msg)
{
	if (!strncmp(msg, "GW:", 3))
		return cache_gw(&msg[3]);

	if (!strncmp(msg, "IFUP:", 5))
		return cache_if(&msg[5], 1);

	if (!strncmp(msg, "IFDN:", 5))
		return cache_if(&msg[5], 0);

	if (!strncmp(msg, "IFDEL:", 6))
		return free_if(&msg[6]);

	return 0; /* No chnage, unknown event. */
}

int event_cache_gw(void)
{
	return gwup;
}

int event_cache_if(char *ifname)
{
	struct ifc *entry = find_if(ifname);

	if (!entry)
		return 0;
	
	return entry->updown;
}

static int validate_events(char *events)
{
	return !events || !events[0];
}

int event_service_cond(char *events)
{
	int cond = 1;
	char *msg;
	char temp[MAX_ARG_LEN];

	/* No required events, condition satisfied */
	if (validate_events(events))
		return cond;

	strlcpy(temp, events, sizeof(temp));
	msg = strtok(temp, ",");
	while (msg) {
		_d("Looking for %s (in %s), cond %d", msg, events, cond);

		if (!strncmp(msg, "GW", 2))
			cond &= event_cache_gw();
		else if (!strncmp(msg, "IFUP:", 5))
			cond &= event_cache_if(&msg[5]);
		else if (!strncmp(msg, "IFDN:", 5))
			cond &= event_cache_if(&msg[5]);
		else
			_e("Unknown event %s, discarding.", msg);

		_d("=> cond %d", cond);
		msg = strtok(NULL, ",");
	}

	return cond;
}

/*
 * Dispatch an event
 *
 * Called by initctl (via api.c) or plugins/netlink.so
 * May also cache for future reference.
 */
void event_dispatch(char *msg)
{
	int change;
	svc_t *svc;

	if (!msg) {
		_e("Invalid message received.");
		return;
	}

	_d("%s", msg);
	change = event_cache(msg);
	if (!change) {
		_d("Nothing to do");
		return;
	}

	/* Iterate over svc_t and call service_restart() for event matches */
	for (svc = svc_iterator(1); svc; svc = svc_iterator(0)) {
		if (svc->type != SVC_TYPE_SERVICE || validate_events(svc->events))
			continue;

		if (change == 1) {
			if (!service_enabled(svc, 1, NULL))
				continue;

			_d("Got event %s, (re)starting %s ...", svc->events, svc->cmd);
			if (!svc->pid) {
				service_start(svc);
				continue;
			}

			if (svc->sighup)
				service_reload(svc);
			else
				service_restart(svc);
		} else { /* change == -1 */
			if (svc->pid && !event_service_cond(svc->events))
				service_stop(svc);
		}
	}
}


/**
 * Local Variables:
 *  version-control: t
 *  indent-tabs-mode: t
 *  c-file-style: "linux"
 * End:
 */