/* SPDX-License-Identifier: AGPL-3.0-or-later
 * Copyright Red Hat
 * Author: David Gibson <david@gibson.dropbear.id.au>
 *
 * inany.h - Types and helpers for handling addresses which could be
 *           IPv6 or IPv4 (encoded as IPv4-mapped IPv6 addresses)
 */

#include <assert.h>

/** union inany_addr - Represents either an IPv4 or IPv6 address
 * @a6:		Address as an IPv6 address, may be IPv4-mapped
 * @_v4._zero:	All zero-bits for an IPv4 address
 * @_v4._one:	All one-bits for an IPv4 address
 * @_v4.a4:	If @a6 is an IPv4 mapped address, this is the raw IPv4 address
 *
 * Fields starting with _ shouldn't be accessed except via helpers.
 */
union inany_addr {
	struct in6_addr a6;
	struct {
		uint8_t _zero[10];
		uint8_t _one[2];
		struct in_addr a4;
	} _v4mapped;
};

/** inany_v4 - Extract IPv4 address, if present, from IPv[46] address
 * @addr:	IPv4 or IPv6 address
 *
 * Return: IPv4 address if @addr is IPv4, NULL otherwise
 */
static inline const struct in_addr *inany_v4(const union inany_addr *addr)
{
	if (!IN6_IS_ADDR_V4MAPPED(&addr->a6))
		return NULL;
	return &addr->_v4mapped.a4;
}

/** inany_equals - Compare two IPv[46] addresses
 * @a, @b:	IPv[46] addresses
 *
 * Return: true if @a and @b are the same address
 */
static inline bool inany_equals(const union inany_addr *a,
				const union inany_addr *b)
{
	return IN6_ARE_ADDR_EQUAL(&a->a6, &b->a6);
}

/** inany_from_af - Set IPv[46] address from IPv4 or IPv6 address
 * @aa:		Pointer to store IPv[46] address
 * @af:		Address family of @addr
 * @addr:	struct in_addr (IPv4) or struct in6_addr (IPv6)
 */
static inline void inany_from_af(union inany_addr *aa, int af, const void *addr)
{
	if (af == AF_INET6) {
		aa->a6 = *((struct in6_addr *)addr);
	} else if (af == AF_INET) {
		memset(&aa->_v4mapped._zero, 0, sizeof(aa->_v4mapped._zero));
		memset(&aa->_v4mapped._one, 0xff, sizeof(aa->_v4mapped._one));
		aa->_v4mapped.a4 = *((struct in_addr *)addr);
	} else {
		/* Not valid to call with other address families */
		assert(0);
	}
}