#define _GNU_SOURCE

#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/syscall.h>

#include <linux/rtnetlink.h>
#include <linux/sockios.h>
#include <linux/if_vlan.h>
#include <linux/if_bridge.h>

#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <glob.h>

#include <netlink/msg.h>
#include <netlink/attr.h>
#include <netlink/socket.h>
#include <libubox/uloop.h>

#include "netifd.h"
#include "device.h"
#include "system.h"

struct event_socket {
	struct uloop_fd uloop;
	struct nl_sock *sock;
	struct nl_cb *cb;
};

static int sock_ioctl = -1;
static struct nl_sock *sock_rtnl = NULL;

static int cb_rtnl_event(struct nl_msg *msg, void *arg);
static void handle_hotplug_event(struct uloop_fd *u, unsigned int events);

static void
handler_nl_event(struct uloop_fd *u, unsigned int events)
{
	struct event_socket *ev = container_of(u, struct event_socket, uloop);
	nl_recvmsgs(ev->sock, ev->cb);
}

static struct nl_sock *
create_socket(int protocol, int groups)
{
	struct nl_sock *sock;

	sock = nl_socket_alloc();
	if (!sock)
		return NULL;

	if (groups)
		nl_join_groups(sock, groups);

	if (nl_connect(sock, protocol))
		return NULL;

	return sock;
}

static bool
create_raw_event_socket(struct event_socket *ev, int protocol, int groups,
			uloop_fd_handler cb)
{
	ev->sock = create_socket(protocol, groups);
	if (!ev->sock)
		return false;

	ev->uloop.fd = nl_socket_get_fd(ev->sock);
	ev->uloop.cb = cb;
	uloop_fd_add(&ev->uloop, ULOOP_READ | ULOOP_EDGE_TRIGGER);
	return true;
}

static bool
create_event_socket(struct event_socket *ev, int protocol,
		    int (*cb)(struct nl_msg *msg, void *arg))
{
	// Prepare socket for link events
	ev->cb = nl_cb_alloc(NL_CB_DEFAULT);
	if (!ev->cb)
		return false;

	nl_cb_set(ev->cb, NL_CB_VALID, NL_CB_CUSTOM, cb, NULL);

	return create_raw_event_socket(ev, protocol, 0, handler_nl_event);
}

int system_init(void)
{
	static struct event_socket rtnl_event;
	static struct event_socket hotplug_event;

	sock_ioctl = socket(AF_LOCAL, SOCK_DGRAM, 0);
	fcntl(sock_ioctl, F_SETFD, fcntl(sock_ioctl, F_GETFD) | FD_CLOEXEC);

	// Prepare socket for routing / address control
	sock_rtnl = create_socket(NETLINK_ROUTE, 0);
	if (!sock_rtnl)
		return -1;

	if (!create_event_socket(&rtnl_event, NETLINK_ROUTE, cb_rtnl_event))
		return -1;

	if (!create_raw_event_socket(&hotplug_event, NETLINK_KOBJECT_UEVENT, 1,
				     handle_hotplug_event))
		return -1;

	// Receive network link events form kernel
	nl_socket_add_membership(rtnl_event.sock, RTNLGRP_LINK);

	return 0;
}

static void system_set_sysctl(const char *path, const char *val)
{
	int fd;

	fd = open(path, O_WRONLY);
	if (fd < 0)
		return;

	write(fd, val, strlen(val));
	close(fd);
}

static void system_set_dev_sysctl(const char *path, const char *device, const char *val)
{
	static char buf[256];

	snprintf(buf, sizeof(buf), path, val);
	system_set_sysctl(buf, val);
}

static void system_set_disable_ipv6(struct device *dev, const char *val)
{
	system_set_dev_sysctl("/proc/sys/net/ipv6/conf/%s/disable_ipv6", dev->ifname, val);
}

// Evaluate netlink messages
static int cb_rtnl_event(struct nl_msg *msg, void *arg)
{
	struct nlmsghdr *nh = nlmsg_hdr(msg);
	struct ifinfomsg *ifi = NLMSG_DATA(nh);
	struct nlattr *nla[__IFLA_MAX];

	if (nh->nlmsg_type != RTM_DELLINK && nh->nlmsg_type != RTM_NEWLINK)
		goto out;

	nlmsg_parse(nh, sizeof(*ifi), nla, __IFLA_MAX - 1, NULL);
	if (!nla[IFLA_IFNAME])
		goto out;

	struct device *dev = device_get(RTA_DATA(nla[IFLA_IFNAME]), false);
	if (!dev)
		goto out;

	dev->ifindex = ifi->ifi_index;
	/* TODO: parse link status */

out:
	return 0;
}

static void
handle_hotplug_msg(char *data, int size)
{
	const char *subsystem = NULL, *interface = NULL;
	char *cur, *end, *sep;
	struct device *dev;
	int skip;
	bool add;

	if (!strncmp(data, "add@", 4))
		add = true;
	else if (!strncmp(data, "remove@", 7))
		add = false;
	else
		return;

	skip = strlen(data) + 1;
	end = data + size;

	for (cur = data + skip; cur < end; cur += skip) {
		skip = strlen(cur) + 1;

		sep = strchr(cur, '=');
		if (!sep)
			continue;

		*sep = 0;
		if (!strcmp(cur, "INTERFACE"))
			interface = sep + 1;
		else if (!strcmp(cur, "SUBSYSTEM")) {
			subsystem = sep + 1;
			if (strcmp(subsystem, "net") != 0)
				return;
		}
		if (subsystem && interface)
			goto found;
	}
	return;

found:
	dev = device_get(interface, false);
	if (!dev)
		return;

	if (dev->type != &simple_device_type)
		return;

	device_set_present(dev, add);
}

static void
handle_hotplug_event(struct uloop_fd *u, unsigned int events)
{
	struct event_socket *ev = container_of(u, struct event_socket, uloop);
	struct sockaddr_nl nla;
	unsigned char *buf = NULL;
	int size;

	while ((size = nl_recv(ev->sock, &nla, &buf, NULL)) > 0) {
		if (nla.nl_pid == 0)
			handle_hotplug_msg((char *) buf, size);

		free(buf);
	}
}

static int system_rtnl_call(struct nl_msg *msg)
{
	int s = -(nl_send_auto_complete(sock_rtnl, msg)
			|| nl_wait_for_ack(sock_rtnl));
	nlmsg_free(msg);
	return s;
}

int system_bridge_delbr(struct device *bridge)
{
	return ioctl(sock_ioctl, SIOCBRDELBR, bridge->ifname);
}

static int system_bridge_if(const char *bridge, struct device *dev, int cmd, void *data)
{
	struct ifreq ifr;
	if (dev)
		ifr.ifr_ifindex = dev->ifindex;
	else
		ifr.ifr_data = data;
	strncpy(ifr.ifr_name, bridge, sizeof(ifr.ifr_name));
	return ioctl(sock_ioctl, cmd, &ifr);
}

int system_bridge_addif(struct device *bridge, struct device *dev)
{
	system_set_disable_ipv6(dev, "1");
	return system_bridge_if(bridge->ifname, dev, SIOCBRADDIF, NULL);
}

int system_bridge_delif(struct device *bridge, struct device *dev)
{
	system_set_disable_ipv6(dev, "0");
	return system_bridge_if(bridge->ifname, dev, SIOCBRDELIF, NULL);
}

static bool system_is_bridge(const char *name, char *buf, int buflen)
{
	struct stat st;

	snprintf(buf, buflen, "/sys/devices/virtual/net/%s/bridge", name);
	if (stat(buf, &st) < 0)
		return false;

	return true;
}

static char *system_get_bridge(const char *name, char *buf, int buflen)
{
	char *path;
	ssize_t len;
	glob_t gl;

	snprintf(buf, buflen, "/sys/devices/virtual/net/*/brif/%s/bridge", name);
	if (glob(buf, GLOB_NOSORT, NULL, &gl) < 0)
		return NULL;

	if (gl.gl_pathc == 0)
		return NULL;

	len = readlink(gl.gl_pathv[0], buf, buflen);
	if (len < 0)
		return NULL;

	buf[len] = 0;
	path = strrchr(buf, '/');
	if (!path)
		return NULL;

	return path + 1;
}

static int system_if_resolve(struct device *dev)
{
	struct ifreq ifr;
	strncpy(ifr.ifr_name, dev->ifname, sizeof(ifr.ifr_name));
	if (!ioctl(sock_ioctl, SIOCGIFINDEX, &ifr))
		return ifr.ifr_ifindex;
	else
		return 0;
}

static int system_if_flags(const char *ifname, unsigned add, unsigned rem)
{
	struct ifreq ifr;
	strncpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
	ioctl(sock_ioctl, SIOCGIFFLAGS, &ifr);
	ifr.ifr_flags |= add;
	ifr.ifr_flags &= ~rem;
	return ioctl(sock_ioctl, SIOCSIFFLAGS, &ifr);
}

struct clear_data {
	struct nl_msg *msg;
	struct device *dev;
	int type;
	int size;
	int af;
};


static bool check_ifaddr(struct nlmsghdr *hdr, int ifindex)
{
	struct ifaddrmsg *ifa = NLMSG_DATA(hdr);

	return ifa->ifa_index == ifindex;
}

static bool check_route(struct nlmsghdr *hdr, int ifindex)
{
	struct nlattr *tb[__RTA_MAX];

	nlmsg_parse(hdr, sizeof(struct rtmsg), tb, __RTA_MAX - 1, NULL);
	if (!tb[RTA_OIF])
		return false;

	return *(int *)RTA_DATA(tb[RTA_OIF]) == ifindex;
}

static int cb_clear_event(struct nl_msg *msg, void *arg)
{
	struct clear_data *clr = arg;
	struct nlmsghdr *hdr = nlmsg_hdr(msg);
	bool (*cb)(struct nlmsghdr *, int ifindex);
	int type;

	switch(clr->type) {
	case RTM_GETADDR:
		type = RTM_DELADDR;
		if (hdr->nlmsg_type != RTM_NEWADDR)
			return NL_SKIP;

		cb = check_ifaddr;
		break;
	case RTM_GETROUTE:
		type = RTM_DELROUTE;
		if (hdr->nlmsg_type != RTM_NEWROUTE)
			return NL_SKIP;

		cb = check_route;
		break;
	default:
		return NL_SKIP;
	}

	if (!cb(hdr, clr->dev->ifindex))
		return NL_SKIP;

	D(SYSTEM, "Remove %s from device %s\n",
	  type == RTM_DELADDR ? "an address" : "a route",
	  clr->dev->ifname);
	memcpy(nlmsg_hdr(clr->msg), hdr, hdr->nlmsg_len);
	hdr = nlmsg_hdr(clr->msg);
	hdr->nlmsg_type = type;
	hdr->nlmsg_flags = NLM_F_REQUEST;

	if (!nl_send_auto_complete(sock_rtnl, clr->msg))
		nl_wait_for_ack(sock_rtnl);

	return NL_SKIP;
}

static int
cb_finish_event(struct nl_msg *msg, void *arg)
{
	int *pending = arg;
	*pending = 0;
	return NL_STOP;
}

static int
error_handler(struct sockaddr_nl *nla, struct nlmsgerr *err, void *arg)
{
	int *pending = arg;
	*pending = err->error;
	return NL_STOP;
}

static void
system_if_clear_entries(struct device *dev, int type, int af)
{
	struct clear_data clr;
	struct nl_cb *cb = nl_cb_alloc(NL_CB_DEFAULT);
	struct rtmsg rtm = {
		.rtm_family = af,
		.rtm_flags = RTM_F_CLONED,
	};
	int flags = NLM_F_DUMP;
	int pending = 1;

	clr.af = af;
	clr.dev = dev;
	clr.type = type;
	switch (type) {
	case RTM_GETADDR:
		clr.size = sizeof(struct rtgenmsg);
		break;
	case RTM_GETROUTE:
		clr.size = sizeof(struct rtmsg);
		break;
	default:
		return;
	}

	if (!cb)
		return;

	clr.msg = nlmsg_alloc_simple(type, flags);
	if (!clr.msg)
		goto out;

	nlmsg_append(clr.msg, &rtm, clr.size, 0);
	nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, cb_clear_event, &clr);
	nl_cb_set(cb, NL_CB_FINISH, NL_CB_CUSTOM, cb_finish_event, &pending);
	nl_cb_err(cb, NL_CB_CUSTOM, error_handler, &pending);

	nl_send_auto_complete(sock_rtnl, clr.msg);
	while (pending > 0)
		nl_recvmsgs(sock_rtnl, cb);

	nlmsg_free(clr.msg);
out:
	nl_cb_put(cb);
}

/*
 * Clear bridge (membership) state and bring down device
 */
void system_if_clear_state(struct device *dev)
{
	static char buf[256];
	char *bridge;

	if (dev->external)
		return;

	dev->ifindex = system_if_resolve(dev);
	if (!dev->ifindex)
		return;

	system_if_flags(dev->ifname, 0, IFF_UP);

	if (system_is_bridge(dev->ifname, buf, sizeof(buf))) {
		D(SYSTEM, "Delete existing bridge named '%s'\n", dev->ifname);
		system_bridge_delbr(dev);
		return;
	}

	bridge = system_get_bridge(dev->ifname, buf, sizeof(buf));
	if (bridge) {
		D(SYSTEM, "Remove device '%s' from bridge '%s'\n", dev->ifname, bridge);
		system_bridge_if(bridge, dev, SIOCBRDELIF, NULL);
	}

	system_if_clear_entries(dev, RTM_GETROUTE, AF_INET);
	system_if_clear_entries(dev, RTM_GETADDR, AF_INET);
	system_if_clear_entries(dev, RTM_GETROUTE, AF_INET6);
	system_if_clear_entries(dev, RTM_GETADDR, AF_INET6);
	system_set_disable_ipv6(dev, "0");
}

static inline unsigned long
sec_to_jiffies(int val)
{
	return (unsigned long) val * 100;
}

int system_bridge_addbr(struct device *bridge, struct bridge_config *cfg)
{
	unsigned long args[4] = {};

	if (ioctl(sock_ioctl, SIOCBRADDBR, bridge->ifname) < 0)
		return -1;

	args[0] = BRCTL_SET_BRIDGE_STP_STATE;
	args[1] = !!cfg->stp;
	system_bridge_if(bridge->ifname, NULL, SIOCDEVPRIVATE, &args);

	args[0] = BRCTL_SET_BRIDGE_FORWARD_DELAY;
	args[1] = sec_to_jiffies(cfg->forward_delay);
	system_bridge_if(bridge->ifname, NULL, SIOCDEVPRIVATE, &args);

	system_set_dev_sysctl("/sys/devices/virtual/net/%s/bridge/multicast_snooping",
		bridge->ifname, cfg->igmp_snoop ? "1" : "0");

	if (cfg->flags & BRIDGE_OPT_AGEING_TIME) {
		args[0] = BRCTL_SET_AGEING_TIME;
		args[1] = sec_to_jiffies(cfg->ageing_time);
		system_bridge_if(bridge->ifname, NULL, SIOCDEVPRIVATE, &args);
	}

	if (cfg->flags & BRIDGE_OPT_HELLO_TIME) {
		args[0] = BRCTL_SET_BRIDGE_HELLO_TIME;
		args[1] = sec_to_jiffies(cfg->hello_time);
		system_bridge_if(bridge->ifname, NULL, SIOCDEVPRIVATE, &args);
	}

	if (cfg->flags & BRIDGE_OPT_MAX_AGE) {
		args[0] = BRCTL_SET_BRIDGE_MAX_AGE;
		args[1] = sec_to_jiffies(cfg->max_age);
		system_bridge_if(bridge->ifname, NULL, SIOCDEVPRIVATE, &args);
	}

	return 0;
}

static int system_vlan(struct device *dev, int id)
{
	struct vlan_ioctl_args ifr = {
		.cmd = SET_VLAN_NAME_TYPE_CMD,
		.u.name_type = VLAN_NAME_TYPE_RAW_PLUS_VID_NO_PAD,
	};

	ioctl(sock_ioctl, SIOCSIFVLAN, &ifr);

	if (id < 0) {
		ifr.cmd = DEL_VLAN_CMD;
		ifr.u.VID = 0;
	} else {
		ifr.cmd = ADD_VLAN_CMD;
		ifr.u.VID = id;
	}
	strncpy(ifr.device1, dev->ifname, sizeof(ifr.device1));
	return ioctl(sock_ioctl, SIOCSIFVLAN, &ifr);
}

int system_vlan_add(struct device *dev, int id)
{
	return system_vlan(dev, id);
}

int system_vlan_del(struct device *dev)
{
	return system_vlan(dev, -1);
}

static void
system_if_apply_settings(struct device *dev)
{
	struct ifreq ifr;

	memset(&ifr, 0, sizeof(ifr));
	strncpy(ifr.ifr_name, dev->ifname, sizeof(ifr.ifr_name));
	if (dev->flags & DEV_OPT_MTU) {
		ifr.ifr_mtu = dev->mtu;
		ioctl(sock_ioctl, SIOCSIFMTU, &ifr);
	}
	if (dev->flags & DEV_OPT_TXQUEUELEN) {
		ifr.ifr_qlen = dev->txqueuelen;
		ioctl(sock_ioctl, SIOCSIFTXQLEN, &ifr);
	}
	if (dev->flags & DEV_OPT_MACADDR) {
		memcpy(&ifr.ifr_hwaddr, dev->macaddr, sizeof(dev->macaddr));
		ioctl(sock_ioctl, SIOCSIFHWADDR, &ifr);
	}

	dev->ifindex = system_if_resolve(dev);
}

int system_if_up(struct device *dev)
{
	system_if_apply_settings(dev);
	return system_if_flags(dev->ifname, IFF_UP, 0);
}

int system_if_down(struct device *dev)
{
	return system_if_flags(dev->ifname, 0, IFF_UP);
}

int system_if_check(struct device *dev)
{
	device_set_present(dev, (system_if_resolve(dev) > 0));
	return 0;
}

struct device *
system_if_get_parent(struct device *dev)
{
	char buf[64], *devname;
	int ifindex, iflink, len;
	FILE *f;

	snprintf(buf, sizeof(buf), "/sys/class/net/%s/iflink", dev->ifname);
	f = fopen(buf, "r");
	if (!f)
		return NULL;

	len = fread(buf, 1, sizeof(buf) - 1, f);
	fclose(f);

	if (len <= 0)
		return NULL;

	buf[len] = 0;
	iflink = strtoul(buf, NULL, 0);
	ifindex = system_if_resolve(dev);
	if (!iflink || iflink == ifindex)
		return NULL;

	devname = if_indextoname(iflink, buf);
	if (!devname)
		return NULL;

	return device_get(devname, true);
}

int system_if_dump_stats(struct device *dev, struct blob_buf *b)
{
	const char *const counters[] = {
		"collisions",     "rx_frame_errors",   "tx_compressed",
		"multicast",      "rx_length_errors",  "tx_dropped",
		"rx_bytes",       "rx_missed_errors",  "tx_errors",
		"rx_compressed",  "rx_over_errors",    "tx_fifo_errors",
		"rx_crc_errors",  "rx_packets",        "tx_heartbeat_errors",
		"rx_dropped",     "tx_aborted_errors", "tx_packets",
		"rx_errors",      "tx_bytes",          "tx_window_errors",
		"rx_fifo_errors", "tx_carrier_errors",
	};
	char buf[64];
	int stats_dir;
	int i, fd, len;

	snprintf(buf, sizeof(buf), "/sys/class/net/%s/statistics", dev->ifname);
	stats_dir = open(buf, O_DIRECTORY);
	if (stats_dir < 0)
		return -1;

	for (i = 0; i < ARRAY_SIZE(counters); i++) {
		fd = openat(stats_dir, counters[i], O_RDONLY);
		if (fd < 0)
			continue;

retry:
		len = read(fd, buf, sizeof(buf));
		if (len < 0) {
			if (errno == EINTR)
				goto retry;
			continue;
		}

		buf[len] = 0;
		blobmsg_add_u32(b, counters[i], strtoul(buf, NULL, 0));
		close(fd);
	}

	close(stats_dir);
	return 0;
}

static int system_addr(struct device *dev, struct device_addr *addr, int cmd)
{
	int alen = ((addr->flags & DEVADDR_FAMILY) == DEVADDR_INET4) ? 4 : 16;
	struct ifaddrmsg ifa = {
		.ifa_family = (alen == 4) ? AF_INET : AF_INET6,
		.ifa_prefixlen = addr->mask,
		.ifa_index = dev->ifindex,
	};

	struct nl_msg *msg;

	dev = addr->device;
	if (dev) {
		if (!dev->ifindex)
			return -1;

		ifa.ifa_index = dev->ifindex;
	}

	msg = nlmsg_alloc_simple(cmd, 0);
	if (!msg)
		return -1;

	nlmsg_append(msg, &ifa, sizeof(ifa), 0);
	nla_put(msg, IFA_LOCAL, alen, &addr->addr);
	return system_rtnl_call(msg);
}

int system_add_address(struct device *dev, struct device_addr *addr)
{
	return system_addr(dev, addr, RTM_NEWADDR);
}

int system_del_address(struct device *dev, struct device_addr *addr)
{
	return system_addr(dev, addr, RTM_DELADDR);
}

static int system_rt(struct device *dev, struct device_route *route, int cmd)
{
	int alen = ((route->flags & DEVADDR_FAMILY) == DEVADDR_INET4) ? 4 : 16;
	bool have_gw;
	unsigned int flags = 0;
	int ifindex = dev->ifindex;

	if (alen == 4)
		have_gw = !!route->nexthop.in.s_addr;
	else
		have_gw = route->nexthop.in6.s6_addr32[0] ||
			route->nexthop.in6.s6_addr32[1] ||
			route->nexthop.in6.s6_addr32[2] ||
			route->nexthop.in6.s6_addr32[3];

	unsigned char scope = (cmd == RTM_DELROUTE) ? RT_SCOPE_NOWHERE :
			(have_gw) ? RT_SCOPE_UNIVERSE : RT_SCOPE_LINK;

	struct rtmsg rtm = {
		.rtm_family = (alen == 4) ? AF_INET : AF_INET6,
		.rtm_dst_len = route->mask,
		.rtm_table = RT_TABLE_MAIN,
		.rtm_protocol = RTPROT_BOOT,
		.rtm_scope = scope,
		.rtm_type = (cmd == RTM_DELROUTE) ? 0: RTN_UNICAST,
	};
	struct nl_msg *msg;

	if (cmd == RTM_NEWROUTE)
		flags |= NLM_F_CREATE | NLM_F_REPLACE;

	dev = route->device;
	if (dev) {
		if (!dev->ifindex)
			return -1;

		ifindex = dev->ifindex;
	}

	msg = nlmsg_alloc_simple(cmd, flags);
	if (!msg)
		return -1;

	nlmsg_append(msg, &rtm, sizeof(rtm), 0);

	if (route->mask)
		nla_put(msg, RTA_DST, alen, &route->addr);

	if (have_gw)
		nla_put(msg, RTA_GATEWAY, alen, &route->nexthop);

	if (route->flags & DEVADDR_DEVICE)
		nla_put_u32(msg, RTA_OIF, ifindex);

	return system_rtnl_call(msg);
}

int system_add_route(struct device *dev, struct device_route *route)
{
	return system_rt(dev, route, RTM_NEWROUTE);
}

int system_del_route(struct device *dev, struct device_route *route)
{
	return system_rt(dev, route, RTM_DELROUTE);
}

int system_flush_routes(void)
{
	const char *names[] = {
		"/proc/sys/net/ipv4/route/flush",
		"/proc/sys/net/ipv6/route/flush"
	};
	int fd, i;

	for (i = 0; i < ARRAY_SIZE(names); i++) {
		fd = open(names[i], O_WRONLY);
		if (fd < 0)
			continue;

		write(fd, "-1", 2);
		close(fd);
	}
	return 0;
}

time_t system_get_rtime(void)
{
	struct timespec ts;
	struct timeval tv;

	if (syscall(__NR_clock_gettime, CLOCK_MONOTONIC, &ts) == 0)
		return ts.tv_sec;

	if (gettimeofday(&tv, NULL) == 0)
		return tv.tv_sec;

	return 0;
}