/*
 *
 *  Connection Manager
 *
 *  Copyright (C) 2011  Nokia Corporation. All rights reserved.
 *  Copyright (C) Alexey Kuznetsov et al. from iproute2 package.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2 as
 *  published by the Free Software Foundation.
 *
 *  This program 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 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 St, Fifth Floor, Boston, MA  02110-1301  USA
 *
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <net/if.h>
#include <linux/ip.h>
#include <linux/if_tunnel.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
#include <sys/ioctl.h>
#include <unistd.h>

#include "connman.h"
#include <connman/log.h>
#include <connman/ipconfig.h>
#include "gweb/gweb.h"

static int tunnel_created;
static int tunnel_pending;
static char *tunnel_ip_address;
static GWeb *web;
static guint web_request_id;

#define STATUS_URL "http://ipv6.connman.net/online/status.html"

#define NLMSG_TAIL(nmsg) \
	((struct rtattr *) (((void *)(nmsg)) + NLMSG_ALIGN((nmsg)->nlmsg_len)))

#ifndef IP_DF
#define IP_DF		0x4000		/* Flag: "Don't Fragment"	*/
#endif

struct rtnl_handle {
	int			fd;
	struct sockaddr_nl	local;
	struct sockaddr_nl	peer;
	__u32			seq;
	__u32			dump;
};

static int addattr32(struct nlmsghdr *n, int maxlen, int type, __u32 data)
{
	int len = RTA_LENGTH(4);
	struct rtattr *rta;
	if (NLMSG_ALIGN(n->nlmsg_len) + len > (unsigned int)maxlen) {
		DBG("Error! max allowed bound %d exceeded", maxlen);
		return -1;
	}
	rta = NLMSG_TAIL(n);
	rta->rta_type = type;
	rta->rta_len = len;
	memcpy(RTA_DATA(rta), &data, 4);
	n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + len;

	return 0;
}

static int addattr_l(struct nlmsghdr *n, int maxlen, int type,
			const void *data, int alen)
{
	int len = RTA_LENGTH(alen);
	struct rtattr *rta;

	if (NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len) >
					(unsigned int)maxlen) {
		DBG("addattr_l message exceeded bound of %d", maxlen);
		return -1;
	}
	rta = NLMSG_TAIL(n);
	rta->rta_type = type;
	rta->rta_len = len;
	memcpy(RTA_DATA(rta), data, alen);
	n->nlmsg_len = NLMSG_ALIGN(n->nlmsg_len) + RTA_ALIGN(len);

	return 0;
}

static void rtnl_close(struct rtnl_handle *rth)
{
	if (rth->fd >= 0) {
		close(rth->fd);
		rth->fd = -1;
	}
}

static int rtnl_open(struct rtnl_handle *rth)
{
	socklen_t addr_len;
	int sndbuf = 1024;

	memset(rth, 0, sizeof(*rth));

	rth->fd = socket(AF_NETLINK, SOCK_RAW | SOCK_CLOEXEC, NETLINK_ROUTE);
	if (rth->fd < 0) {
		connman_error("Can not open netlink socket: %s",
						strerror(errno));
		return -1;
	}

	if (setsockopt(rth->fd, SOL_SOCKET, SO_SNDBUF, &sndbuf,
			sizeof(sndbuf)) < 0) {
		connman_error("SO_SNDBUF: %s", strerror(errno));
		return -1;
	}

	memset(&rth->local, 0, sizeof(rth->local));
	rth->local.nl_family = AF_NETLINK;
	rth->local.nl_groups = 0;

	if (bind(rth->fd, (struct sockaddr *)&rth->local,
			sizeof(rth->local)) < 0) {
		connman_error("Can not bind netlink socket: %s",
							strerror(errno));
		return -1;
	}
	addr_len = sizeof(rth->local);
	if (getsockname(rth->fd, (struct sockaddr *)&rth->local,
				&addr_len) < 0) {
		connman_error("Can not getsockname: %s", strerror(errno));
		return -1;
	}
	if (addr_len != sizeof(rth->local)) {
		connman_error("Wrong address length %d", addr_len);
		return -1;
	}
	if (rth->local.nl_family != AF_NETLINK) {
		connman_error("Wrong address family %d", rth->local.nl_family);
		return -1;
	}
	rth->seq = time(NULL);

	return 0;
}

static int rtnl_talk(struct rtnl_handle *rtnl, struct nlmsghdr *n)
{
	struct sockaddr_nl nladdr;
	struct iovec iov = {
		.iov_base = (void *)n,
		.iov_len = n->nlmsg_len
	};
	struct msghdr msg = {
		.msg_name = &nladdr,
		.msg_namelen = sizeof(nladdr),
		.msg_iov = &iov,
		.msg_iovlen = 1,
	};
	unsigned seq;
	int err;

	memset(&nladdr, 0, sizeof(nladdr));
	nladdr.nl_family = AF_NETLINK;

	n->nlmsg_seq = seq = ++rtnl->seq;
	n->nlmsg_flags |= NLM_F_ACK;

	err = sendmsg(rtnl->fd, &msg, 0);
	if (err < 0) {
		connman_error("Can not talk to rtnetlink");
		return err;
	}

	return 0;
}

static int tunnel_create(struct in_addr *addr)
{
	struct ip_tunnel_parm p;
	struct ifreq ifr;
	int fd = -1;
	int ret;

	/* ip tunnel add tun6to4 mode sit remote any local 1.2.3.4 ttl 64 */

	memset(&p, 0, sizeof(struct ip_tunnel_parm));
	memset(&ifr, 0, sizeof(struct ifreq));

	p.iph.version = 4;
	p.iph.ihl = 5;
	p.iph.frag_off = htons(IP_DF);
	p.iph.protocol = IPPROTO_IPV6;
	p.iph.saddr = addr->s_addr;
	p.iph.ttl = 64;
	strncpy(p.name, "tun6to4", IFNAMSIZ);

	strncpy(ifr.ifr_name, "sit0", IFNAMSIZ);
	ifr.ifr_ifru.ifru_data = (void *)&p;
	fd = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0);
	ret = ioctl(fd, SIOCADDTUNNEL, &ifr);
	if (ret)
		connman_error("add tunnel %s failed: %s", ifr.ifr_name,
							strerror(errno));
	close(fd);

	return ret;
}

static void tunnel_destroy()
{
	struct ip_tunnel_parm p;
	struct ifreq ifr;
	int fd = -1;
	int ret;

	if (tunnel_created == 0)
		return;

	/* ip tunnel del tun6to4 */

	memset(&p, 0, sizeof(struct ip_tunnel_parm));
	memset(&ifr, 0, sizeof(struct ifreq));

	p.iph.version = 4;
	p.iph.ihl = 5;
	p.iph.protocol = IPPROTO_IPV6;
	strncpy(p.name, "tun6to4", IFNAMSIZ);

	strncpy(ifr.ifr_name, "tun6to4", IFNAMSIZ);
	ifr.ifr_ifru.ifru_data = (void *)&p;
	fd = socket(AF_INET, SOCK_DGRAM | SOCK_CLOEXEC, 0);
	if (fd < 0) {
		connman_error("socket failed: %s", strerror(errno));
		return;
	}

	ret = ioctl(fd, SIOCDELTUNNEL, &ifr);
	if (ret)
		connman_error("del tunnel %s failed: %s", ifr.ifr_name,
							strerror(errno));
	else
		tunnel_created = 0;

	tunnel_pending = 0;
	close(fd);

	g_free(tunnel_ip_address);
	tunnel_ip_address = NULL;
}

static int tunnel_add_route()
{
	struct rtnl_handle rth;
	struct in6_addr addr6;
	int index;
	int ret = 0;

	struct {
		struct nlmsghdr n;
		struct rtmsg 	r;
		char   		buf[1024];
	} req;

	/* ip -6 route add ::/0 via ::192.88.99.1 dev tun6to4 metric 1 */

	index = if_nametoindex("tun6to4");
	if (index == 0) {
		DBG("Can not find device tun6to4");
		return -1;
	}

	memset(&req, 0, sizeof(req));

	req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct rtmsg));
	req.n.nlmsg_flags = NLM_F_REQUEST | NLM_F_CREATE | NLM_F_EXCL;
	req.n.nlmsg_type = RTM_NEWROUTE;
	req.r.rtm_family = AF_INET6;
	req.r.rtm_table = RT_TABLE_MAIN;
	req.r.rtm_protocol = RTPROT_BOOT;
	req.r.rtm_scope = RT_SCOPE_UNIVERSE;
	req.r.rtm_type = RTN_UNICAST;
	req.r.rtm_dst_len = 0;

	inet_pton(AF_INET6, "::192.88.99.1", &addr6);

	addattr_l(&req.n, sizeof(req), RTA_GATEWAY, &addr6.s6_addr, 16);
	addattr32(&req.n, sizeof(req), RTA_OIF, index);
	addattr32(&req.n, sizeof(req), RTA_PRIORITY, 1);

	ret = rtnl_open(&rth);
	if (ret < 0)
		goto done;

	ret = rtnl_talk(&rth, &req.n);

done:
	rtnl_close(&rth);
	return ret;
}

static int tunnel_set_addr(unsigned int a, unsigned int b,
			unsigned int c, unsigned int d)
{
	struct rtnl_handle rth;
	struct in6_addr addr6;
	char *ip6addr;
	int ret;

	struct {
		struct nlmsghdr n;
		struct ifaddrmsg ifa;
		char buf[256];
	} req;

	/* ip -6 addr add dev tun6to4 2002:0102:0304::1/64 */

	memset(&req, 0, sizeof(req));

	req.n.nlmsg_len = NLMSG_LENGTH(sizeof(struct ifaddrmsg));
	req.n.nlmsg_flags = NLM_F_REQUEST | NLM_F_CREATE | NLM_F_EXCL;
	req.n.nlmsg_type = RTM_NEWADDR;
	req.ifa.ifa_family = AF_INET6;
	req.ifa.ifa_prefixlen = 64;
	req.ifa.ifa_index = if_nametoindex("tun6to4");
	if (req.ifa.ifa_index == 0) {
		connman_error("Can not find device tun6to4");
		ret = -1;
		goto done;
	}

	ip6addr = g_strdup_printf("2002:%02x%02x:%02x%02x::1", a, b, c, d);
	inet_pton(AF_INET6, ip6addr, &addr6);
	DBG("ipv6 address %s", ip6addr);
	g_free(ip6addr);

	addattr_l(&req.n, sizeof(req), IFA_LOCAL, &addr6.s6_addr, 16);
	addattr_l(&req.n, sizeof(req), IFA_ADDRESS, &addr6.s6_addr, 16);

	ret = rtnl_open(&rth);
	if (ret < 0)
		goto done;

	ret = rtnl_talk(&rth, &req.n);

done:
	rtnl_close(&rth);
	return ret;
}

static gboolean unref_web(gpointer user_data)
{
	g_web_unref(web);
	return FALSE;
}

static gboolean web_result(GWebResult *result, gpointer user_data)
{
	guint16 status;

	if (web_request_id == 0)
		return FALSE;

	status = g_web_result_get_status(result);

	DBG("status %u", status);

	if (status >= 400 && status < 500)
		tunnel_destroy();
	else
		tunnel_pending = 0;

	web_request_id = 0;

	g_timeout_add_seconds(1, unref_web, NULL);

	return FALSE;
}

static int init_6to4(struct in_addr *ip4addr)
{
	unsigned int a, b, c, d;
	int ret, if_index;
	in_addr_t addr;

	DBG("");

	addr = ntohl(ip4addr->s_addr);

	a = (addr & 0xff000000) >> 24;
	b = (addr & 0x00ff0000) >> 16;
	c = (addr & 0x0000ff00) >> 8;
	d = addr & 0x000000ff;

	ret = tunnel_create(ip4addr);
	if (ret)
		return -1;

	tunnel_created = 1;

	ret = connman_inet_setup_tunnel("tun6to4", 1472);
	if (ret)
		goto error;

	ret = tunnel_set_addr(a, b, c, d);
	if (ret)
		goto error;

	ret = tunnel_add_route();
	if (ret)
		goto error;

	if_index = connman_inet_ifindex("tun6to4");
	if (if_index < 0)
		goto error;

	/* We try to verify that connectivity through tunnel works ok.
	 */
	web = g_web_new(if_index);
	if (web == NULL)
		goto error;

	g_web_set_accept(web, NULL);
	g_web_set_user_agent(web, "ConnMan/%s", VERSION);
	g_web_set_close_connection(web, TRUE);

	web_request_id = g_web_request_get(web, STATUS_URL, web_result, NULL);

	return 0;

error:
	tunnel_destroy();
	return -1;
}

static void receive_rs_reply(struct nd_router_advert *reply,
			unsigned int length, void *user_data)
{
	char *address = user_data;
	struct in_addr ip4addr;

	DBG("reply %p len %d address %s", reply, length, address);

	/* We try to create tunnel if autoconfiguration did not work i.e.,
	 * we did not receive any reply to router solicitation message.
	 */
	if (reply == NULL && inet_aton(address, &ip4addr) != 0)
		init_6to4(&ip4addr);

	g_free(address);
}

int __connman_6to4_probe(struct connman_service *service)
{
	struct connman_ipconfig *ip4config, *ip6config;
	enum connman_ipconfig_method method;
	unsigned int a, b;
	struct in_addr ip4addr;
	in_addr_t addr;
	const char *address;
	char *ip_address;
	int index;

	DBG("service %p", service);

	if (tunnel_created || tunnel_pending)
		return 0;

	if (service == NULL)
		return -1;

	ip4config = __connman_service_get_ip4config(service);
	if (ip4config == NULL)
		return -1;

	ip6config = __connman_service_get_ip6config(service);
	if (ip6config == NULL)
		return -1;

	method = __connman_ipconfig_get_method(ip6config);
	if (method != CONNMAN_IPCONFIG_METHOD_AUTO)
		return -1;

	address = __connman_ipconfig_get_local(ip4config);
	if (address == NULL)
		return -1;

	if (inet_aton(address, &ip4addr) == 0)
		return -1;

	addr = ntohl(ip4addr.s_addr);

	a = (addr & 0xff000000) >> 24;
	b = (addr & 0x00ff0000) >> 16;

	/* 6to4 tunnel is only usable if we have a public IPv4 address */
	if (a == 10 || (a == 192 && b == 168) ||
					(a == 172 && (b >= 16 && b <= 31)))
		return -1;

	index = __connman_ipconfig_get_index(ip4config);
	ip_address = g_strdup(address);
	tunnel_pending = 1;

	g_free(tunnel_ip_address);
	tunnel_ip_address = g_strdup(address);

	return __connman_inet_ipv6_send_rs(index, 2, receive_rs_reply,
							ip_address);
}

void __connman_6to4_remove(struct connman_ipconfig *ip4config)
{
	const char *address;

	DBG("tunnel ip address %s", tunnel_ip_address);

	if (ip4config == NULL)
		return;

	address = __connman_ipconfig_get_local(ip4config);
	if (address == NULL)
		return;

	if (g_strcmp0(address, tunnel_ip_address) != 0)
		return;

	if (tunnel_created)
		tunnel_destroy();
}

int __connman_6to4_check(struct connman_ipconfig *ip4config)
{
	const char *address;

	if (ip4config == NULL || tunnel_created == 0 ||
					tunnel_pending == 1)
		return -1;

	DBG("tunnel ip address %s", tunnel_ip_address);

	address = __connman_ipconfig_get_local(ip4config);
	if (address == NULL)
		return -1;

	if (g_strcmp0(address, tunnel_ip_address) == 0)
		return 1;

	return 0;
}