/* 
 * Copyright © 2005-2008  Red Hat, Inc. All rights reserved.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions of the
 * GNU General Public License v.2.  This program is distributed in the hope
 * that it will be useful, but WITHOUT ANY WARRANTY expressed or implied,
 * including the implied warranties of MERCHANTABILITY or FITNESS FOR A
 * PARTICULAR PURPOSE. See the GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc., 51
 * Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. Any Red Hat
 * trademarks that are incorporated in the source code or documentation are not
 * subject to the GNU General Public License and may only be used or replicated
 * with the express permission of Red Hat, Inc.
 *
 * Red Hat Author(s): Nathan Straz <nstraz@redhat.com>
 *                    Dean Jansa <djansa@redhat.com>
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <netdb.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

#include "btime_int.h"

static void gen_cookie(char *s);
/*
 * btime_init -- 
 *
 * 	Prepare a socket to use for getting boot time from btimed
 */

int
btime_init(const char *host)
{
	int sd = 0;
	struct addrinfo *serv_ail, *serv_aip;
	struct addrinfo *my_ail, *my_aip;
	struct addrinfo hints;

	memset(&hints, 0, sizeof hints);
	hints.ai_family = AF_UNSPEC;
	hints.ai_socktype = SOCK_DGRAM;
	if (getaddrinfo(host, "5016", &hints, &serv_ail) != 0) {
		fprintf(stderr, "Could not get address info for %s: %s\n",
		        host, strerror(errno));
		return 0;
	}
	
	for (serv_aip = serv_ail; serv_aip != NULL; serv_aip = serv_aip->ai_next) {
		if ((sd = socket(serv_aip->ai_family, serv_aip->ai_socktype, 
		                 serv_aip->ai_protocol)) < 0) {
			continue;
		}

		break;
	}

	if (serv_aip == NULL) {
		fprintf(stderr, "Could not create socket: %s\n", strerror(errno));
		sd = 0;
		goto free_serv;
	}

	memset(&hints, 0, sizeof hints);
	hints.ai_family = AF_UNSPEC;
	hints.ai_socktype = SOCK_DGRAM;
	hints.ai_flags = AI_PASSIVE;     /* Fill in my IP for me */
	if (getaddrinfo(NULL, "0", &hints, &my_ail) != 0) {
		fprintf(stderr, "Could not get address info for myself!: %s\n", strerror(errno));
		sd = 0;
		goto free_serv;
	}

	for (my_aip = my_ail; my_aip != NULL; my_aip = my_aip->ai_next) {
		if (bind(sd, my_aip->ai_addr, my_aip->ai_addrlen) < 0) {
			continue;
		}

		break;
	}

	if (my_aip == NULL) {
		fprintf(stderr, "Could not bind to local address: %s\n", 
	   	     strerror(errno));
		sd = 0;
		goto free_my;
	}

	if (connect(sd, serv_aip->ai_addr, serv_aip->ai_addrlen) < 0) {
		fprintf(stderr, "Could not connect to host: %s\n",
				strerror(errno));
		sd = 0;
	}

free_my:
	freeaddrinfo(my_ail);
free_serv:
	freeaddrinfo(serv_ail);

	return sd;
}

/*
 * btime_do --
 *
 * 	Get the boot time from btimed using an already prepared socket
 *
 * Returns:
 *	btime, or 0 on failure.
 */
unsigned int
btime_do(const int sd)
{
	char cookie[BTIME_MSGLEN];
	char response[BTIME_MSGLEN];
	unsigned int btime = 0;
	ssize_t nbytes;	
	int retry;
	fd_set sdset;
	struct timeval timeout;

	memset(cookie, 0, BTIME_MSGLEN);
	gen_cookie(cookie);
	for (retry = 0; retry < MAX_RETRY; retry++) {
		if ((nbytes = send(sd, &cookie, BTIME_MSGLEN, MSG_DONTWAIT)) < 0) {
			if (errno == EAGAIN) {
				usleep(retry * 100);
			} else {
				/* Non EAGAIN error... */
				break;
			}
		} else {
			break;
		}
	}
	
	FD_ZERO(&sdset);
	FD_SET(sd, &sdset);
	do {
		retry = 0;

		timeout.tv_sec = 0;
		timeout.tv_usec = 500000;

		if (select(sd + 1, &sdset, NULL, NULL, &timeout) != 1) {
			/* Either an error or a timeout, we don't need to retry */
			break;
		}

		memset(response, 0, BTIME_MSGLEN);
		nbytes = recv(sd, &response, BTIME_MSGLEN, MSG_DONTWAIT);

		if (nbytes == 0) continue; /* Nothing received */

		if (response[0] == 'B' && response[1] == 'T') {
			/* Check for new style cookie */
			if (memcmp(cookie, response, COOKIE_LEN) == 0) {
				btime = strtoul(response+COOKIE_LEN, NULL, 10);
				break;
			} else {
				/* ignore the invalid btime cookie */
				retry = 1;
				continue;
			}
		}
	} while (retry);

	return btime;
}

/*
 * btime --
 * 
 *	Return the boot time of a remote host if that host is running the
 *	btimed deamon.
 *
 * Returns:
 *	btime, or 0 on failure.
 */

unsigned int
btime(const char *host)
{
	int s;
	unsigned int b;
	s = btime_init(host);
	b = btime_do(s);
	close(s);

	return b;
}

/* gen_cookie
 *
 * 	Generate a random string that btimed will send back to us.
 */
static void gen_cookie(char *s)
{
	char *a = s;
	int i;

	*a++ = 'B';
	*a++ = 'T';
	for (i = 0; i < COOKIE_RANDOM_PARTS; i++) {
		*(int32_t *)a = (int32_t)random();
		a += sizeof(int32_t);
	}
	*a = '\n';
}