/*
 * netifd - network interface daemon
 * Copyright (C) 2012 Felix Fietkau <nbd@openwrt.org>
 *
 * 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.
 */
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>

#include <arpa/inet.h>

#include "netifd.h"
#include "device.h"
#include "interface.h"
#include "interface-ip.h"
#include "proto.h"
#include "ubus.h"
#include "system.h"

enum {
	ROUTE_INTERFACE,
	ROUTE_TARGET,
	ROUTE_MASK,
	ROUTE_GATEWAY,
	ROUTE_METRIC,
	ROUTE_MTU,
	__ROUTE_MAX
};

static const struct blobmsg_policy route_attr[__ROUTE_MAX] = {
	[ROUTE_INTERFACE] = { .name = "interface", .type = BLOBMSG_TYPE_STRING },
	[ROUTE_TARGET] = { .name = "target", .type = BLOBMSG_TYPE_STRING },
	[ROUTE_MASK] = { .name = "netmask", .type = BLOBMSG_TYPE_STRING },
	[ROUTE_GATEWAY] = { .name = "gateway", .type = BLOBMSG_TYPE_STRING },
	[ROUTE_METRIC] = { .name = "metric", .type = BLOBMSG_TYPE_INT32 },
	[ROUTE_MTU] = { .name = "mtu", .type = BLOBMSG_TYPE_INT32 },
};

const struct config_param_list route_attr_list = {
	.n_params = __ROUTE_MAX,
	.params = route_attr,
};

static void
clear_if_addr(union if_addr *a, int mask)
{
	int m_bytes = (mask + 7) / 8;
	uint8_t m_clear = (1 << (m_bytes * 8 - mask)) - 1;
	uint8_t *p = (uint8_t *) a;

	if (m_bytes < sizeof(a))
		memset(p + m_bytes, 0, sizeof(a) - m_bytes);

	p[m_bytes - 1] &= ~m_clear;
}

static bool
match_if_addr(union if_addr *a1, union if_addr *a2, int mask)
{
	union if_addr *p1, *p2;

	p1 = alloca(sizeof(*a1));
	p2 = alloca(sizeof(*a2));

	memcpy(p1, a1, sizeof(*a1));
	clear_if_addr(p1, mask);
	memcpy(p2, a2, sizeof(*a2));
	clear_if_addr(p2, mask);

	return !memcmp(p1, p2, sizeof(*p1));
}

static bool
__find_ip_addr_target(struct interface_ip_settings *ip, union if_addr *a, bool v6)
{
	struct device_addr *addr;

	vlist_for_each_element(&ip->addr, addr, node) {
		if (!addr->enabled)
			continue;

		if (v6 != ((addr->flags & DEVADDR_FAMILY) == DEVADDR_INET6))
			continue;

		if (!match_if_addr(&addr->addr, a, addr->mask))
			continue;

		return true;
	}

	return false;
}

static void
__find_ip_route_target(struct interface_ip_settings *ip, union if_addr *a,
		       bool v6, struct device_route **res)
{
	struct device_route *route;

	vlist_for_each_element(&ip->route, route, node) {
		if (!route->enabled)
			continue;

		if (v6 != ((route->flags & DEVADDR_FAMILY) == DEVADDR_INET6))
			continue;

		if (!match_if_addr(&route->addr, a, route->mask))
			continue;

		if (!*res || route->mask < (*res)->mask)
			*res = route;
	}
}

static bool
interface_ip_find_addr_target(struct interface *iface, union if_addr *a, bool v6)
{
	return __find_ip_addr_target(&iface->proto_ip, a, v6) ||
	       __find_ip_addr_target(&iface->config_ip, a, v6);
}

static void
interface_ip_find_route_target(struct interface *iface, union if_addr *a,
			       bool v6, struct device_route **route)
{
	__find_ip_route_target(&iface->proto_ip, a, v6, route);
	__find_ip_route_target(&iface->config_ip, a, v6, route);
}

struct interface *
interface_ip_add_target_route(union if_addr *addr, bool v6)
{
	struct interface *iface;
	struct device_route *route, *r_next = NULL;
	bool defaultroute_target = false;
	int addrsize = v6 ? sizeof(addr->in6) : sizeof(addr->in);

	route = calloc(1, sizeof(*route));
	if (!route)
		return NULL;

	route->flags = v6 ? DEVADDR_INET6 : DEVADDR_INET4;
	route->mask = v6 ? 128 : 32;
	if (memcmp(&route->addr, addr, addrsize) == 0)
		defaultroute_target = true;
	else
		memcpy(&route->addr, addr, addrsize);

	vlist_for_each_element(&interfaces, iface, node) {
		/* look for locally addressable target first */
		if (interface_ip_find_addr_target(iface, addr, v6))
			goto done;

		/* do not stop at the first route, let the lookup compare
		 * masks to find the best match */
		interface_ip_find_route_target(iface, addr, v6, &r_next);
	}

	if (!r_next) {
		free(route);
		return NULL;
	}

	iface = r_next->iface;
	memcpy(&route->nexthop, &r_next->nexthop, sizeof(route->nexthop));
	route->mtu = r_next->mtu;
	route->metric = r_next->metric;

done:
	route->iface = iface;
	if (defaultroute_target)
		free(route);
	else
		vlist_add(&iface->host_routes, &route->node, &route->flags);
	return iface;
}

void
interface_ip_add_route(struct interface *iface, struct blob_attr *attr, bool v6)
{
	struct interface_ip_settings *ip;
	struct blob_attr *tb[__ROUTE_MAX], *cur;
	struct device_route *route;
	int af = v6 ? AF_INET6 : AF_INET;

	blobmsg_parse(route_attr, __ROUTE_MAX, tb, blobmsg_data(attr), blobmsg_data_len(attr));

	if (!iface) {
		if ((cur = tb[ROUTE_INTERFACE]) == NULL)
			return;

		iface = vlist_find(&interfaces, blobmsg_data(cur), iface, node);
		if (!iface)
			return;

		ip = &iface->config_ip;
	} else {
		ip = &iface->proto_ip;
	}

	route = calloc(1, sizeof(*route));
	if (!route)
		return;

	route->flags = v6 ? DEVADDR_INET6 : DEVADDR_INET4;
	route->mask = v6 ? 128 : 32;
	if ((cur = tb[ROUTE_MASK]) != NULL) {
		route->mask = parse_netmask_string(blobmsg_data(cur), v6);
		if (route->mask > (v6 ? 128 : 32))
			goto error;
	}

	if ((cur = tb[ROUTE_TARGET]) != NULL) {
		if (!parse_ip_and_netmask(af, blobmsg_data(cur), &route->addr, &route->mask)) {
			DPRINTF("Failed to parse route target: %s\n", (char *) blobmsg_data(cur));
			goto error;
		}
	}

	if ((cur = tb[ROUTE_GATEWAY]) != NULL) {
		if (!inet_pton(af, blobmsg_data(cur), &route->nexthop)) {
			DPRINTF("Failed to parse route gateway: %s\n", (char *) blobmsg_data(cur));
			goto error;
		}
	}

	if ((cur = tb[ROUTE_METRIC]) != NULL) {
		route->metric = blobmsg_get_u32(cur);
		route->flags |= DEVROUTE_METRIC;
	}

	if ((cur = tb[ROUTE_MTU]) != NULL) {
		route->mtu = blobmsg_get_u32(cur);
		route->flags |= DEVROUTE_MTU;
	}

	vlist_add(&ip->route, &route->node, &route->flags);
	return;

error:
	free(route);
}

static int
addr_cmp(const void *k1, const void *k2, void *ptr)
{
	return memcmp(k1, k2, sizeof(struct device_addr) -
		      offsetof(struct device_addr, flags));
}

static int
route_cmp(const void *k1, const void *k2, void *ptr)
{
	return memcmp(k1, k2, sizeof(struct device_route) -
		      offsetof(struct device_route, flags));
}

static void
interface_handle_subnet_route(struct interface *iface, struct device_addr *addr, bool add)
{
	struct device *dev = iface->l3_dev.dev;
	struct device_route route;

	memset(&route, 0, sizeof(route));
	route.iface = iface;
	route.flags = addr->flags;
	route.mask = addr->mask;
	memcpy(&route.addr, &addr->addr, sizeof(route.addr));
	clear_if_addr(&route.addr, route.mask);

	if (add) {
		route.flags |= DEVADDR_KERNEL;
		system_del_route(dev, &route);

		route.flags &= ~DEVADDR_KERNEL;
		route.metric = iface->metric;
		system_add_route(dev, &route);
	} else {
		system_del_route(dev, &route);
	}
}

static void
interface_update_proto_addr(struct vlist_tree *tree,
			    struct vlist_node *node_new,
			    struct vlist_node *node_old)
{
	struct interface_ip_settings *ip;
	struct interface *iface;
	struct device *dev;
	struct device_addr *a_new = NULL, *a_old = NULL;
	bool keep = false;

	ip = container_of(tree, struct interface_ip_settings, addr);
	iface = ip->iface;
	dev = iface->l3_dev.dev;

	if (node_new) {
		a_new = container_of(node_new, struct device_addr, node);

		if ((a_new->flags & DEVADDR_FAMILY) == DEVADDR_INET4 &&
		    !a_new->broadcast) {

			uint32_t mask = ~0;
			uint32_t *a = (uint32_t *) &a_new->addr;

			mask >>= a_new->mask;
			a_new->broadcast = *a | htonl(mask);
		}
	}

	if (node_old)
		a_old = container_of(node_old, struct device_addr, node);

	if (a_new && a_old) {
		keep = true;

		if (a_old->flags != a_new->flags)
			keep = false;

		if ((a_new->flags & DEVADDR_FAMILY) == DEVADDR_INET4 &&
		    a_new->broadcast != a_old->broadcast)
			keep = false;
	}

	if (node_old) {
		if (!(a_old->flags & DEVADDR_EXTERNAL) && a_old->enabled && !keep) {
			interface_handle_subnet_route(iface, a_old, false);
			system_del_address(dev, a_old);
		}
		free(a_old);
	}

	if (node_new) {
		a_new->enabled = true;
		if (!(a_new->flags & DEVADDR_EXTERNAL) && !keep) {
			system_add_address(dev, a_new);
			if (iface->metric)
				interface_handle_subnet_route(iface, a_new, true);
		}
	}
}

static bool
enable_route(struct interface_ip_settings *ip, struct device_route *route)
{
	if (ip->no_defaultroute && !route->mask)
		return false;

	return ip->enabled;
}

static void
interface_update_proto_route(struct vlist_tree *tree,
			     struct vlist_node *node_new,
			     struct vlist_node *node_old)
{
	struct interface_ip_settings *ip;
	struct interface *iface;
	struct device *dev;
	struct device_route *route_old, *route_new;
	bool keep = false;

	ip = container_of(tree, struct interface_ip_settings, route);
	iface = ip->iface;
	dev = iface->l3_dev.dev;

	route_old = container_of(node_old, struct device_route, node);
	route_new = container_of(node_new, struct device_route, node);

	if (node_old && node_new)
		keep = !memcmp(&route_old->nexthop, &route_new->nexthop, sizeof(route_old->nexthop));

	if (node_old) {
		if (!(route_old->flags & DEVADDR_EXTERNAL) && route_old->enabled && !keep)
			system_del_route(dev, route_old);
		free(route_old);
	}

	if (node_new) {
		bool _enabled = enable_route(ip, route_new);

		if (!(route_new->flags & DEVROUTE_METRIC))
			route_new->metric = iface->metric;

		if (!(route_new->flags & DEVADDR_EXTERNAL) && !keep && _enabled)
			system_add_route(dev, route_new);

		route_new->iface = iface;
		route_new->enabled = _enabled;
	}
}

static void
interface_update_host_route(struct vlist_tree *tree,
			     struct vlist_node *node_new,
			     struct vlist_node *node_old)
{
	struct interface *iface;
	struct device *dev;
	struct device_route *route_old, *route_new;

	iface = container_of(tree, struct interface, host_routes);
	dev = iface->l3_dev.dev;

	route_old = container_of(node_old, struct device_route, node);
	route_new = container_of(node_new, struct device_route, node);

	if (node_old) {
		system_del_route(dev, route_old);
		free(route_old);
	}

	if (node_new)
		system_add_route(dev, route_new);
}

void
interface_add_dns_server(struct interface_ip_settings *ip, const char *str)
{
	struct dns_server *s;

	s = calloc(1, sizeof(*s));
	if (!s)
		return;

	s->af = AF_INET;
	if (inet_pton(s->af, str, &s->addr.in))
		goto add;

	s->af = AF_INET6;
	if (inet_pton(s->af, str, &s->addr.in))
		goto add;

	free(s);
	return;

add:
	D(INTERFACE, "Add IPv%c DNS server: %s\n",
	  s->af == AF_INET6 ? '6' : '4', str);
	vlist_simple_add(&ip->dns_servers, &s->node);
}

void
interface_add_dns_server_list(struct interface_ip_settings *ip, struct blob_attr *list)
{
	struct blob_attr *cur;
	int rem;

	blobmsg_for_each_attr(cur, list, rem) {
		if (blobmsg_type(cur) != BLOBMSG_TYPE_STRING)
			continue;

		if (!blobmsg_check_attr(cur, NULL))
			continue;

		interface_add_dns_server(ip, blobmsg_data(cur));
	}
}

static void
interface_add_dns_search_domain(struct interface_ip_settings *ip, const char *str)
{
	struct dns_search_domain *s;
	int len = strlen(str);

	s = calloc(1, sizeof(*s) + len + 1);
	if (!s)
		return;

	D(INTERFACE, "Add DNS search domain: %s\n", str);
	memcpy(s->name, str, len);
	vlist_simple_add(&ip->dns_search, &s->node);
}

void
interface_add_dns_search_list(struct interface_ip_settings *ip, struct blob_attr *list)
{
	struct blob_attr *cur;
	int rem;

	blobmsg_for_each_attr(cur, list, rem) {
		if (blobmsg_type(cur) != BLOBMSG_TYPE_STRING)
			continue;

		if (!blobmsg_check_attr(cur, NULL))
			continue;

		interface_add_dns_search_domain(ip, blobmsg_data(cur));
	}
}

static void
write_resolv_conf_entries(FILE *f, struct interface_ip_settings *ip)
{
	struct dns_server *s;
	struct dns_search_domain *d;
	const char *str;
	char buf[32];

	vlist_simple_for_each_element(&ip->dns_servers, s, node) {
		str = inet_ntop(s->af, &s->addr, buf, sizeof(buf));
		if (!str)
			continue;

		fprintf(f, "nameserver %s\n", str);
	}

	vlist_simple_for_each_element(&ip->dns_search, d, node) {
		fprintf(f, "search %s\n", d->name);
	}
}

void
interface_write_resolv_conf(void)
{
	struct interface *iface;
	char *path = alloca(strlen(resolv_conf) + 5);
	FILE *f;

	sprintf(path, "%s.tmp", resolv_conf);
	unlink(path);
	f = fopen(path, "w");
	if (!f) {
		D(INTERFACE, "Failed to open %s for writing\n", path);
		return;
	}

	vlist_for_each_element(&interfaces, iface, node) {
		if (iface->state != IFS_UP)
			continue;

		if (vlist_simple_empty(&iface->proto_ip.dns_search) &&
		    vlist_simple_empty(&iface->proto_ip.dns_servers) &&
			vlist_simple_empty(&iface->config_ip.dns_search) &&
		    vlist_simple_empty(&iface->config_ip.dns_servers))
			continue;

		fprintf(f, "# Interface %s\n", iface->name);
		write_resolv_conf_entries(f, &iface->config_ip);
		if (!iface->proto_ip.no_dns)
			write_resolv_conf_entries(f, &iface->proto_ip);
	}
	fclose(f);
	if (rename(path, resolv_conf) < 0) {
		D(INTERFACE, "Failed to replace %s\n", resolv_conf);
		unlink(path);
	}
}

void interface_ip_set_enabled(struct interface_ip_settings *ip, bool enabled)
{
	struct device_addr *addr;
	struct device_route *route;
	struct device *dev;

	ip->enabled = enabled;
	dev = ip->iface->l3_dev.dev;
	if (!dev)
		return;

	vlist_for_each_element(&ip->addr, addr, node) {
		if (addr->enabled == enabled)
			continue;

		if (enabled)
			system_add_address(dev, addr);
		else
			system_del_address(dev, addr);
		addr->enabled = enabled;
	}

	vlist_for_each_element(&ip->route, route, node) {
		bool _enabled = enabled;

		if (!enable_route(ip, route))
			_enabled = false;

		if (route->enabled == _enabled)
			continue;

		if (_enabled) {
			if (!(route->flags & DEVROUTE_METRIC))
				route->metric = ip->iface->metric;

			system_add_route(dev, route);
		} else
			system_del_route(dev, route);
		route->enabled = _enabled;
	}
}

void
interface_ip_update_start(struct interface_ip_settings *ip)
{
	if (ip != &ip->iface->config_ip) {
		vlist_simple_update(&ip->dns_servers);
		vlist_simple_update(&ip->dns_search);
	}
	vlist_update(&ip->route);
	vlist_update(&ip->addr);
}

void
interface_ip_update_complete(struct interface_ip_settings *ip)
{
	vlist_simple_flush(&ip->dns_servers);
	vlist_simple_flush(&ip->dns_search);
	vlist_flush(&ip->route);
	vlist_flush(&ip->addr);
	interface_write_resolv_conf();
}

void
interface_ip_flush(struct interface_ip_settings *ip)
{
	if (ip == &ip->iface->proto_ip)
		vlist_flush_all(&ip->iface->host_routes);
	vlist_simple_flush_all(&ip->dns_servers);
	vlist_simple_flush_all(&ip->dns_search);
	vlist_flush_all(&ip->route);
	vlist_flush_all(&ip->addr);
}

static void
__interface_ip_init(struct interface_ip_settings *ip, struct interface *iface)
{
	ip->iface = iface;
	ip->enabled = true;
	vlist_simple_init(&ip->dns_search, struct dns_search_domain, node);
	vlist_simple_init(&ip->dns_servers, struct dns_server, node);
	vlist_init(&ip->route, route_cmp, interface_update_proto_route);
	vlist_init(&ip->addr, addr_cmp, interface_update_proto_addr);
}

void
interface_ip_init(struct interface *iface)
{
	__interface_ip_init(&iface->proto_ip, iface);
	__interface_ip_init(&iface->config_ip, iface);
	vlist_init(&iface->host_routes, route_cmp, interface_update_host_route);
}