/*
 * Copyright (c) 2011-2012 The DragonFly Project.  All rights reserved.
 *
 * This code is derived from software contributed to The DragonFly Project
 * by Matthew Dillon <dillon@dragonflybsd.org>
 * by Venkatesh Srinivas <vsrinivas@dragonflybsd.org>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 3. Neither the name of The DragonFly Project nor the names of its
 *    contributors may be used to endorse or promote products derived
 *    from this software without specific, prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include "hammer2.h"

static void *master_accept(void *data);
static void master_auth_signal(hammer2_router_t *router);
static void master_auth_rxmsg(hammer2_msg_t *msg);
static void master_link_signal(hammer2_router_t *router);
static void master_link_rxmsg(hammer2_msg_t *msg);
static void master_reconnect(const char *mntpt);

/*
 * Start-up the master listener daemon for the machine.
 *
 * The master listener serves as a rendezvous point in the cluster, accepting
 * connections, performing registrations and authentications, maintaining
 * the spanning tree, and keeping track of message state so disconnects can
 * be handled properly.
 *
 * Once authenticated only low-level messaging protocols (which includes
 * tracking persistent messages) are handled by this daemon.  This daemon
 * does not run the higher level quorum or locking protocols.
 *
 * This daemon can also be told to maintain connections to other nodes,
 * forming a messaging backbone, which in turn allows PFS's (if desired) to
 * simply connect to the master daemon via localhost if desired.
 * Backbones are specified via /etc/hammer2.conf.
 */
int
cmd_service(void)
{
	struct sockaddr_in lsin;
	int on;
	int lfd;

	/*
	 * Acquire socket and set options
	 */
	if ((lfd = socket(AF_INET, SOCK_STREAM, 0)) < 0) {
		fprintf(stderr, "master_listen: socket(): %s\n",
			strerror(errno));
		return 1;
	}
	on = 1;
	setsockopt(lfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));

	/*
	 * Setup listen port and try to bind.  If the bind fails we assume
	 * that a master listener process is already running and silently
	 * fail.
	 */
	bzero(&lsin, sizeof(lsin));
	lsin.sin_family = AF_INET;
	lsin.sin_addr.s_addr = INADDR_ANY;
	lsin.sin_port = htons(HAMMER2_LISTEN_PORT);
	if (bind(lfd, (struct sockaddr *)&lsin, sizeof(lsin)) < 0) {
		close(lfd);
		if (QuietOpt == 0) {
			fprintf(stderr,
				"master listen: daemon already running\n");
		}
		return 0;
	}
	if (QuietOpt == 0)
		fprintf(stderr, "master listen: startup\n");
	listen(lfd, 50);

	/*
	 * Fork and disconnect the controlling terminal and parent process,
	 * executing the specified function as a pthread.
	 *
	 * Returns to the original process which can then continue running.
	 * In debug mode this call will create the pthread without forking
	 * and set NormalExit to 0, instead of fork.
	 */
	hammer2_demon(master_accept, (void *)(intptr_t)lfd);
	if (NormalExit)
		close(lfd);
	return 0;
}

/*
 * Master listen/accept thread.  Accept connections on the master socket,
 * starting a pthread for each one.
 */
static
void *
master_accept(void *data)
{
	struct sockaddr_in asin;
	socklen_t alen;
	pthread_t thread;
	hammer2_master_service_info_t *info;
	int lfd = (int)(intptr_t)data;
	int fd;
	int i;
	int count;
	struct statfs *mntbuf = NULL;
	struct statvfs *mntvbuf = NULL;

	/*
	 * Nobody waits for us
	 */
	setproctitle("hammer2 master listen");
	pthread_detach(pthread_self());

	/*
	 * Scan existing hammer2 mounts and reconnect to them using
	 * HAMMER2IOC_RECLUSTER.
	 */
	count = getmntvinfo(&mntbuf, &mntvbuf, MNT_NOWAIT);
	for (i = 0; i < count; ++i) {
		if (strcmp(mntbuf[i].f_fstypename, "hammer2") == 0)
			master_reconnect(mntbuf[i].f_mntonname);
	}

	/*
	 * Accept connections and create pthreads to handle them after
	 * validating the IP.
	 */
	for (;;) {
		alen = sizeof(asin);
		fd = accept(lfd, (struct sockaddr *)&asin, &alen);
		if (fd < 0) {
			if (errno == EINTR)
				continue;
			break;
		}
		thread = NULL;
		fprintf(stderr, "master_accept: accept fd %d\n", fd);
		info = malloc(sizeof(*info));
		bzero(info, sizeof(*info));
		info->fd = fd;
		info->detachme = 1;
		pthread_create(&thread, NULL, master_service, info);
	}
	return (NULL);
}

/*
 * Normally the mount program supplies a cluster communications
 * descriptor to the hammer2 vfs on mount, but if you kill the service
 * daemon and restart it that link will be lost.
 *
 * This procedure attempts to [re]connect to existing mounts when
 * the service daemon is started up before going into its accept
 * loop.
 */
static
void
master_reconnect(const char *mntpt)
{
	struct hammer2_ioc_recluster recls;
	hammer2_master_service_info_t *info;
	pthread_t thread;
	int fd;
	int pipefds[2];

	fd = open(mntpt, O_RDONLY);
	if (fd < 0) {
		fprintf(stderr, "reconnect %s: no access to mount\n", mntpt);
		return;
	}
	if (pipe(pipefds) < 0) {
		fprintf(stderr, "reconnect %s: pipe() failed\n", mntpt);
		return;
	}
	bzero(&recls, sizeof(recls));
	recls.fd = pipefds[0];
	if (ioctl(fd, HAMMER2IOC_RECLUSTER, &recls) < 0) {
		fprintf(stderr, "reconnect %s: ioctl failed\n", mntpt);
		close(pipefds[0]);
		close(pipefds[1]);
		close(fd);
		return;
	}
	close(pipefds[0]);

	info = malloc(sizeof(*info));
	bzero(info, sizeof(*info));
	info->fd = pipefds[1];
	info->detachme = 1;
	pthread_create(&thread, NULL, master_service, info);
}

/*
 * Service an accepted connection (runs as a pthread)
 *
 * (also called from a couple of other places)
 */
void *
master_service(void *data)
{
	hammer2_master_service_info_t *info = data;
	hammer2_iocom_t iocom;

	if (info->detachme)
		pthread_detach(pthread_self());

	hammer2_iocom_init(&iocom, info->fd, -1,
			   master_auth_signal,
			   master_auth_rxmsg,
			   NULL);
	hammer2_iocom_core(&iocom);

	fprintf(stderr,
		"iocom on fd %d terminated error rx=%d, tx=%d\n",
		info->fd, iocom.ioq_rx.error, iocom.ioq_tx.error);
	close(info->fd);
	info->fd = -1;	/* safety */
	free(info);

	return (NULL);
}

/************************************************************************
 *			    AUTHENTICATION				*
 ************************************************************************
 *
 * Callback via hammer2_iocom_core().
 *
 * Additional messaging-based authentication must occur before normal
 * message operation.  The connection has already been encrypted at
 * this point.
 */
static void master_auth_conn_rx(hammer2_msg_t *msg);

static
void
master_auth_signal(hammer2_router_t *router)
{
	hammer2_msg_t *msg;

	/*
	 * Transmit LNK_CONN, enabling the SPAN protocol if both sides
	 * agree.
	 *
	 * XXX put additional authentication states here
	 */
	msg = hammer2_msg_alloc(router, 0, HAMMER2_LNK_CONN |
						   HAMMER2_MSGF_CREATE,
				master_auth_conn_rx, NULL);
	snprintf(msg->any.lnk_conn.label, sizeof(msg->any.lnk_conn.label), "*");
	hammer2_msg_write(msg);

	hammer2_router_restate(router,
			      master_link_signal,
			      master_link_rxmsg,
			      NULL);
}

static
void
master_auth_conn_rx(hammer2_msg_t *msg)
{
	if (msg->any.head.cmd & HAMMER2_MSGF_DELETE)
		hammer2_msg_reply(msg, 0);
}

static
void
master_auth_rxmsg(hammer2_msg_t *msg __unused)
{
}

/************************************************************************
 *			POST-AUTHENTICATION SERVICE MSGS		*
 ************************************************************************
 *
 * Callback via hammer2_iocom_core().
 */
static
void
master_link_signal(hammer2_router_t *router)
{
	hammer2_msg_lnk_signal(router);
}

static
void
master_link_rxmsg(hammer2_msg_t *msg)
{
	hammer2_state_t *state;
	uint32_t cmd;

	/*
	 * If the message state has a function established we just
	 * call the function, otherwise we call the appropriate
	 * link-level protocol related to the original command and
	 * let it sort it out.
	 *
	 * Non-transactional one-off messages, on the otherhand,
	 * might have REPLY set.
	 */
	state = msg->state;
	cmd = state ? state->msg->any.head.cmd : msg->any.head.cmd;

	fprintf(stderr, "service-receive: %s\n", hammer2_msg_str(msg));

	if (state && state->func) {
		assert(state->func != NULL);
		state->func(msg);
	} else {
		switch(cmd & HAMMER2_MSGF_PROTOS) {
		case HAMMER2_MSG_PROTO_LNK:
			hammer2_msg_lnk(msg);
			break;
		case HAMMER2_MSG_PROTO_DBG:
			hammer2_msg_dbg(msg);
			break;
		default:
			hammer2_msg_reply(msg, HAMMER2_MSG_ERR_NOSUPP);
			break;
		}
	}
}