/*
 * Copyright (c) 2019 Intel Corporation.
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <logging/log.h>
LOG_MODULE_DECLARE(net_l2_ppp, CONFIG_NET_L2_PPP_LOG_LEVEL);

#include <net/net_core.h>
#include <net/net_pkt.h>

#include <net/ppp.h>

#include "net_private.h"

#include "ppp_internal.h"

#define ALLOC_TIMEOUT K_MSEC(100)

int ppp_parse_options(struct ppp_fsm *fsm, struct net_pkt *pkt,
		      uint16_t length,
		      int (*parse)(struct net_pkt *pkt, uint8_t code,
				   uint8_t len, void *user_data),
		      void *user_data)
{
	int remaining = length, pkt_remaining;
	uint8_t opt_type, opt_len, opt_val_len;
	int ret;
	struct net_pkt_cursor cursor;

	pkt_remaining = net_pkt_remaining_data(pkt);
	if (remaining != pkt_remaining) {
		NET_DBG("Expecting %d but pkt data length is %d bytes",
			remaining, pkt_remaining);
		return -EMSGSIZE;
	}

	while (remaining > 0) {
		ret = net_pkt_read_u8(pkt, &opt_type);
		if (ret < 0) {
			NET_DBG("Cannot read %s (%d) (remaining len %d)",
				"opt_type", ret, pkt_remaining);
			return -EBADMSG;
		}

		ret = net_pkt_read_u8(pkt, &opt_len);
		if (ret < 0) {
			NET_DBG("Cannot read %s (%d) (remaining len %d)",
				"opt_len", ret, remaining);
			return -EBADMSG;
		}

		opt_val_len = opt_len - sizeof(opt_type) - sizeof(opt_len);

		net_pkt_cursor_backup(pkt, &cursor);

		NET_DBG("[%s/%p] option %s (%d) len %d", fsm->name, fsm,
			ppp_option2str(fsm->protocol, opt_type), opt_type,
			opt_len);

		ret = parse(pkt, opt_type, opt_val_len, user_data);
		if (ret < 0) {
			return ret;
		}

		net_pkt_cursor_restore(pkt, &cursor);

		net_pkt_skip(pkt, opt_val_len);
		remaining -= opt_len;
	}

	if (remaining < 0) {
		return -EBADMSG;
	}

	return 0;
}

static const struct ppp_peer_option_info *
ppp_peer_option_info_get(const struct ppp_peer_option_info *options,
			 size_t num_options,
			 uint8_t code)
{
	size_t i;

	for (i = 0; i < num_options; i++) {
		if (options[i].code == code) {
			return &options[i];
		}
	}

	return NULL;
}

struct ppp_parse_option_conf_req_data {
	struct ppp_fsm *fsm;
	struct net_pkt *ret_pkt;
	enum ppp_protocol_type protocol;
	const struct ppp_peer_option_info *options_info;
	size_t num_options_info;
	void *user_data;

	int nack_count;
	int rej_count;
};

static int ppp_parse_option_conf_req_unsupported(struct net_pkt *pkt,
						 uint8_t code, uint8_t len,
						 void *user_data)
{
	struct ppp_parse_option_conf_req_data *parse_data = user_data;
	struct ppp_fsm *fsm = parse_data->fsm;
	struct net_pkt *ret_pkt = parse_data->ret_pkt;
	const struct ppp_peer_option_info *option_info =
		ppp_peer_option_info_get(parse_data->options_info,
					 parse_data->num_options_info,
					 code);

	NET_DBG("[%s/%p] %s option %s (%d) len %d",
		fsm->name, fsm, "Check",
		ppp_option2str(parse_data->protocol, code),
		code, len);

	if (option_info) {
		return 0;
	}

	parse_data->rej_count++;

	net_pkt_write_u8(ret_pkt, code);
	net_pkt_write_u8(ret_pkt, len + sizeof(code) + sizeof(len));

	if (len > 0) {
		net_pkt_copy(ret_pkt, pkt, len);
	}

	return 0;
}

static int ppp_parse_option_conf_req_supported(struct net_pkt *pkt,
					       uint8_t code, uint8_t len,
					       void *user_data)
{
	struct ppp_parse_option_conf_req_data *parse_data = user_data;
	struct ppp_fsm *fsm = parse_data->fsm;
	const struct ppp_peer_option_info *option_info =
		ppp_peer_option_info_get(parse_data->options_info,
					 parse_data->num_options_info,
					 code);
	int ret;

	ret = option_info->parse(fsm, pkt, parse_data->user_data);
	if (ret == -EINVAL) {
		parse_data->nack_count++;
		ret = option_info->nack(fsm, parse_data->ret_pkt,
					parse_data->user_data);
	}

	return ret;
}

int ppp_config_info_req(struct ppp_fsm *fsm,
			struct net_pkt *pkt,
			uint16_t length,
			struct net_pkt *ret_pkt,
			enum ppp_protocol_type protocol,
			const struct ppp_peer_option_info *options_info,
			size_t num_options_info,
			void *user_data)
{
	struct ppp_parse_option_conf_req_data parse_data = {
		.fsm = fsm,
		.ret_pkt = ret_pkt,
		.protocol = protocol,
		.options_info = options_info,
		.num_options_info = num_options_info,
		.user_data = user_data,
	};
	struct net_pkt_cursor cursor;
	int ret;

	net_pkt_cursor_backup(pkt, &cursor);

	ret = ppp_parse_options(fsm, pkt, length,
				ppp_parse_option_conf_req_unsupported,
				&parse_data);
	if (ret < 0) {
		return -EINVAL;
	}

	if (parse_data.rej_count) {
		return PPP_CONFIGURE_REJ;
	}

	net_pkt_cursor_restore(pkt, &cursor);

	ret = ppp_parse_options(fsm, pkt, length,
				ppp_parse_option_conf_req_supported,
				&parse_data);
	if (ret < 0) {
		return -EINVAL;
	}

	if (parse_data.nack_count) {
		return PPP_CONFIGURE_NACK;
	}

	net_pkt_cursor_restore(pkt, &cursor);
	net_pkt_copy(ret_pkt, pkt, length);

	return PPP_CONFIGURE_ACK;
}

struct net_pkt *ppp_my_options_add(struct ppp_fsm *fsm, size_t packet_len)
{
	struct ppp_context *ctx = ppp_fsm_ctx(fsm);
	const struct ppp_my_option_info *info;
	struct ppp_my_option_data *data;
	struct net_pkt *pkt;
	size_t i;
	int err;

	pkt = net_pkt_alloc_with_buffer(ppp_fsm_iface(fsm), packet_len,
					AF_UNSPEC, 0, PPP_BUF_ALLOC_TIMEOUT);
	if (!pkt) {
		return NULL;
	}

	for (i = 0; i < fsm->my_options.count; i++) {
		info = &fsm->my_options.info[i];
		data = &fsm->my_options.data[i];

		if (data->flags & PPP_MY_OPTION_REJECTED) {
			continue;
		}

		err = net_pkt_write_u8(pkt, info->code);
		if (err) {
			goto unref_pkt;
		}

		err = info->conf_req_add(ctx, pkt);
		if (err) {
			goto unref_pkt;
		}
	}

	return pkt;

unref_pkt:
	net_pkt_unref(pkt);

	return NULL;
}

typedef int (*ppp_my_option_handle_t)(struct ppp_context *ctx,
				      struct net_pkt *pkt, uint8_t len,
				      const struct ppp_my_option_info *info,
				      struct ppp_my_option_data *data);

struct ppp_my_option_handle_data {
	struct ppp_fsm *fsm;
	ppp_my_option_handle_t handle;
};

static int ppp_my_option_get(struct ppp_fsm *fsm, uint8_t code,
			     const struct ppp_my_option_info **info,
			     struct ppp_my_option_data **data)
{
	int i;

	for (i = 0; i < fsm->my_options.count; i++) {
		if (fsm->my_options.info[i].code == code) {
			*info = &fsm->my_options.info[i];
			*data = &fsm->my_options.data[i];
			return 0;
		}
	}

	return -ENOENT;
}

static int ppp_my_option_parse(struct net_pkt *pkt, uint8_t code,
			       uint8_t len, void *user_data)
{
	struct ppp_my_option_handle_data *d = user_data;
	struct ppp_context *ctx = ppp_fsm_ctx(d->fsm);
	const struct ppp_my_option_info *info;
	struct ppp_my_option_data *data;
	int ret;

	ret = ppp_my_option_get(d->fsm, code, &info, &data);
	if (ret < 0) {
		return 0;
	}

	return d->handle(ctx, pkt, len, info, data);
}

static int ppp_my_options_parse(struct ppp_fsm *fsm,
				struct net_pkt *pkt,
				uint16_t length,
				ppp_my_option_handle_t handle)
{
	struct ppp_my_option_handle_data parse_data = {
		.fsm = fsm,
		.handle = handle,
	};

	return ppp_parse_options(fsm, pkt, length, ppp_my_option_parse,
				 &parse_data);
}

static int ppp_my_option_parse_conf_ack(struct ppp_context *ctx,
					struct net_pkt *pkt, uint8_t len,
					const struct ppp_my_option_info *info,
					struct ppp_my_option_data *data)
{
	data->flags |= PPP_MY_OPTION_ACKED;

	if (info->conf_ack_handle) {
		return info->conf_ack_handle(ctx, pkt, len);
	}

	return 0;
}

int ppp_my_options_parse_conf_ack(struct ppp_fsm *fsm,
				  struct net_pkt *pkt,
				  uint16_t length)
{
	return ppp_my_options_parse(fsm, pkt, length,
				    ppp_my_option_parse_conf_ack);
}

static int ppp_my_option_parse_conf_nak(struct ppp_context *ctx,
					struct net_pkt *pkt, uint8_t len,
					const struct ppp_my_option_info *info,
					struct ppp_my_option_data *data)
{
	return info->conf_nak_handle(ctx, pkt, len);
}

int ppp_my_options_parse_conf_nak(struct ppp_fsm *fsm,
				  struct net_pkt *pkt,
				  uint16_t length)
{
	return ppp_my_options_parse(fsm, pkt, length,
				    ppp_my_option_parse_conf_nak);
}

static int ppp_my_option_parse_conf_rej(struct ppp_context *ctx,
					struct net_pkt *pkt, uint8_t len,
					const struct ppp_my_option_info *info,
					struct ppp_my_option_data *data)
{
	data->flags |= PPP_MY_OPTION_REJECTED;

	return 0;
}

int ppp_my_options_parse_conf_rej(struct ppp_fsm *fsm,
				  struct net_pkt *pkt,
				  uint16_t length)
{
	return ppp_my_options_parse(fsm, pkt, length,
				    ppp_my_option_parse_conf_rej);
}

uint32_t ppp_my_option_flags(struct ppp_fsm *fsm, uint8_t code)
{
	const struct ppp_my_option_info *info;
	struct ppp_my_option_data *data;
	int ret;

	ret = ppp_my_option_get(fsm, code, &info, &data);
	if (ret) {
		return false;
	}

	return data->flags;
}