/* called under RCU lock */
struct in_ifaddr *inet_lookup_ifaddr_rcu(struct net *net, __be32 addr)
{
	u32 hash = inet_addr_hash(net, addr);
	struct in_ifaddr *ifa;

	hlist_for_each_entry_rcu(ifa, &inet_addr_lst[hash], hash)
		if (ifa->ifa_local == addr &&
		    net_eq(dev_net(ifa->ifa_dev->dev), net))
			return ifa;

	return NULL;
}

inet_addr_type_dev_table(net, dev, tip) == RTN_LOCAL



static inline struct net_device *ip_dev_find(struct net *net, __be32 addr)
{
	return __ip_dev_find(net, addr, true);
}

/**
 * __ip_dev_find - find the first device with a given source address.
 * @net: the net namespace
 * @addr: the source address
 * @devref: if true, take a reference on the found device
 *
 * If a caller uses devref=false, it should be protected by RCU, or RTNL
 */
struct net_device *__ip_dev_find(struct net *net, __be32 addr, bool devref)
{
	struct net_device *result = NULL;
	struct in_ifaddr *ifa;

	rcu_read_lock();
	ifa = inet_lookup_ifaddr_rcu(net, addr);
	if (!ifa) {
		struct flowi4 fl4 = { .daddr = addr };
		struct fib_result res = { 0 };
		struct fib_table *local;

		/* Fallback to FIB local table so that communication
		 * over loopback subnets work.
		 */
		local = fib_get_table(net, RT_TABLE_LOCAL);
		if (local &&
		    !fib_table_lookup(local, &fl4, &res, FIB_LOOKUP_NOREF) &&
		    res.type == RTN_LOCAL)
			result = FIB_RES_DEV(res);
	} else {
		result = ifa->ifa_dev->dev;
	}
	if (result && devref)
		dev_hold(result);
	rcu_read_unlock();
	return result;
}
EXPORT_SYMBOL(__ip_dev_find);

	rcu_read_lock();
	for_each_netdev_rcu(&init_net, dev) {
		in_dev = __in_dev_get_rcu(dev);
		if (in_dev == NULL) {
			continue;
		}
		in_dev_for_each_ifa_rcu(ifa, in_dev) {
		}
	}
	rcu_read_unlock();

static __be32 confirm_addr_indev(struct in_device *in_dev, __be32 dst,
			      __be32 local, int scope)
{
	unsigned char localnet_scope = RT_SCOPE_HOST;
	const struct in_ifaddr *ifa;
	__be32 addr = 0;
	int same = 0;

	if (unlikely(IN_DEV_ROUTE_LOCALNET(in_dev)))
		localnet_scope = RT_SCOPE_LINK;

	in_dev_for_each_ifa_rcu(ifa, in_dev) {
		unsigned char min_scope = min(ifa->ifa_scope, localnet_scope);

		if (!addr &&
		    (local == ifa->ifa_local || !local) &&
		    min_scope <= scope) {
			addr = ifa->ifa_local;
			if (same)
				break;
		}
		if (!same) {
			same = (!local || inet_ifa_match(local, ifa)) &&
				(!dst || inet_ifa_match(dst, ifa));
			if (same && addr) {
				if (local || !dst)
					break;
				/* Is the selected addr into dst subnet? */
				if (inet_ifa_match(addr, ifa))
					break;
				/* No, then can we use new local src? */
				if (min_scope <= scope) {
					addr = ifa->ifa_local;
					break;
				}
				/* search for large dst subnet for addr */
				same = 0;
			}
		}
	}

	return same ? addr : 0;
}

/*
 * Confirm that local IP address exists using wildcards:
 * - net: netns to check, cannot be NULL
 * - in_dev: only on this interface, NULL=any interface
 * - dst: only in the same subnet as dst, 0=any dst
 * - local: address, 0=autoselect the local address
 * - scope: maximum allowed scope value for the local address
 */
__be32 inet_confirm_addr(struct net *net, struct in_device *in_dev,
			 __be32 dst, __be32 local, int scope)
{
	__be32 addr = 0;
	struct net_device *dev;

	if (in_dev)
		return confirm_addr_indev(in_dev, dst, local, scope);

	rcu_read_lock();
	for_each_netdev_rcu(net, dev) {
		in_dev = __in_dev_get_rcu(dev);
		if (in_dev) {
			addr = confirm_addr_indev(in_dev, dst, local, scope);
			if (addr)
				break;
		}
	}
	rcu_read_unlock();

	return addr;
}
EXPORT_SYMBOL(inet_confirm_addr);