/*
 * Copyright (c) 2019 Ant Financial Services Group.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef _TLE_GATEWAY_H_
#define _TLE_GATEWAY_H_

#ifdef __cplusplus
extern "C" {
#endif

static inline bool
is_ipv4_loopback_addr(in_addr_t addr, struct glue_ctx *ctx)
{
	if (addr == ctx->ipv4 || addr == htonl(INADDR_LOOPBACK))
		return true;
	else
		return false;
}

static inline bool
is_ipv6_loopback_addr(const struct in6_addr *addr, struct glue_ctx *ctx)
{
	if (memcmp(addr, &ctx->ipv6, sizeof(struct in6_addr)) == 0 ||
	    IN6_IS_ADDR_LOOPBACK(addr) ||
	    (IN6_IS_ADDR_V4COMPAT(addr) &&
	     addr->__in6_u.__u6_addr32[3] == htonl(INADDR_LOOPBACK)) ||
	    (IN6_IS_ADDR_V4MAPPED(addr) &&
	     addr->__in6_u.__u6_addr32[3] == htonl(INADDR_LOOPBACK)))
		return true;
	else
		return false;
}

static inline const struct in_addr *
ipv4_gateway_lookup(void *data, const struct in_addr *addr)
{
	uint8_t ls;
	struct glue_ctx *ctx = data;

	if (is_ipv4_loopback_addr(addr->s_addr, ctx))
		return addr;

	ls = 32 - ctx->ipv4_ml;
	if ((addr->s_addr << ls) == (ctx->ipv4 << ls))
		return addr;

	if (ctx->ipv4_gw.s_addr != 0)
		return &ctx->ipv4_gw;

	return addr;
}

static inline const struct in6_addr *
ipv6_gateway_lookup(void *data, const struct in6_addr *addr)
{
	uint8_t ls;
	struct glue_ctx *ctx = data;

	if (is_ipv6_loopback_addr(addr, ctx))
		return addr;

	if (ctx->ipv6_ml <= 64) {
		ls = 64 - ctx->ipv6_ml;
		if ((*(const uint64_t*)addr << ls) ==
		    (*(const uint64_t*)&ctx->ipv6 << ls))
			return addr;
	} else if (*(const uint64_t*)addr == *(const uint64_t*)&ctx->ipv6) {
		ls = 128 - ctx->ipv6_ml;
		if ((*((const uint64_t*)addr + 1) << ls) ==
		    (*((const uint64_t*)&ctx->ipv6 + 1) << ls))
			return addr;
	}

	if (!IN6_IS_ADDR_UNSPECIFIED(&ctx->ipv6_gw))
		return &ctx->ipv6_gw;

	return addr;
}

#ifdef __cplusplus
}
#endif

#endif /* _TLE_GATEWAY_H_ */