/*
 * Copyright (c) 2009 Lukas Mejdrech
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup libnet
 * @{
 */

/** @file
 * IP client interface implementation.
 * @see ip_client.h
 */

#include <errno.h>
#include <sys/types.h>

#include <ip_client.h>
#include <packet_client.h>
#include <ip_header.h>

#include <net/packet.h>

/** Returns the IP header length.
 *
 * @param[in] packet	The packet.
 * @return		The IP header length in bytes.
 * @return		Zero if there is no IP header.
 */
size_t ip_client_header_length(packet_t *packet)
{
	ip_header_t *header;

	header = (ip_header_t *) packet_get_data(packet);
	if (!header || (packet_get_data_length(packet) < sizeof(ip_header_t)))
		return 0;

	return IP_HEADER_LENGTH(header);
}

/** Constructs the IPv4 pseudo header.
 *
 * @param[in] protocol	The transport protocol.
 * @param[in] src	The source address.
 * @param[in] srclen	The source address length.
 * @param[in] dest	The destination address.
 * @param[in] destlen	The destination address length.
 * @param[in] data_length The data length to be set.
 * @param[out] header	The constructed IPv4 pseudo header.
 * @param[out] headerlen The length of the IP pseudo header in bytes.
 * @return		EOK on success.
 * @return		EBADMEM if the header and/or the headerlen parameter is
 *			NULL.
 * @return		EINVAL if the source address and/or the destination
 *			address parameter is NULL.
 * @return		EINVAL if the source address length is less than struct
 *			sockaddr length.
 * @return		EINVAL if the source address length differs from the
 *			destination address length.
 * @return		EINVAL if the source address family differs from the
 *			destination family.
 * @return		EAFNOSUPPORT if the address family is not supported.
 * @return		ENOMEM if there is not enough memory left.
 */
int
ip_client_get_pseudo_header(ip_protocol_t protocol, struct sockaddr *src,
    socklen_t srclen, struct sockaddr *dest, socklen_t destlen,
    size_t data_length, void **header, size_t *headerlen)
{
	ipv4_pseudo_header_t *header_in;
	struct sockaddr_in *address_in;

	if (!header || !headerlen)
		return EBADMEM;

	if (!src || !dest || srclen <= 0 ||
	    (((size_t) srclen < sizeof(struct sockaddr))) ||
	    (srclen != destlen) || (src->sa_family != dest->sa_family)) {
		return EINVAL;
	}

	switch (src->sa_family) {
	case AF_INET:
		if (srclen != sizeof(struct sockaddr_in))
			return EINVAL;
		
		*headerlen = sizeof(*header_in);
		header_in = (ipv4_pseudo_header_t *) malloc(*headerlen);
		if (!header_in)
			return ENOMEM;

		bzero(header_in, *headerlen);
		address_in = (struct sockaddr_in *) dest;
		header_in->destination_address = address_in->sin_addr.s_addr;
		address_in = (struct sockaddr_in *) src;
		header_in->source_address = address_in->sin_addr.s_addr;
		header_in->protocol = protocol;
		header_in->data_length = htons(data_length);
		*header = header_in;
		return EOK;

	// TODO IPv6
/*	case AF_INET6:
		if (addrlen != sizeof(struct sockaddr_in6))
			return EINVAL;

		address_in6 = (struct sockaddr_in6 *) addr;
		return EOK;
*/

	default:
		return EAFNOSUPPORT;
	}
}

/** Prepares the packet to be transfered via IP.
 *
 * The IP header is prefixed.
 *
 * @param[in,out] packet The packet to be prepared.
 * @param[in] protocol	The transport protocol.
 * @param[in] ttl	The time to live counter. The IPDEFTTL is set if zero.
 * @param[in] tos	The type of service.
 * @param[in] dont_fragment The value indicating whether fragmentation is
 *			disabled.
 * @param[in] ipopt_length The prefixed IP options length in bytes.
 * @return		EOK on success.
 * @return		ENOMEM if there is not enough memory left in the packet.
 */
int
ip_client_prepare_packet(packet_t *packet, ip_protocol_t protocol, ip_ttl_t ttl,
    ip_tos_t tos, int dont_fragment, size_t ipopt_length)
{
	ip_header_t *header;
	uint8_t *data;
	size_t padding;

	// compute the padding if IP options are set
	// multiple of 4 bytes
	padding =  ipopt_length % 4;
	if (padding) {
		padding = 4 - padding;
		ipopt_length += padding;
	}

	// prefix the header
	data = (uint8_t *) packet_prefix(packet, sizeof(ip_header_t) + padding);
	if (!data)
		return ENOMEM;

	// add the padding
	while (padding--)
		data[sizeof(ip_header_t) + padding] = IPOPT_NOOP;

	// set the header
	header = (ip_header_t *) data;
	header->header_length = IP_COMPUTE_HEADER_LENGTH(sizeof(ip_header_t) +
	    ipopt_length);
	header->ttl = (ttl ? ttl : IPDEFTTL);
	header->tos = tos;
	header->protocol = protocol;

	if (dont_fragment)
		header->flags = IPFLAG_DONT_FRAGMENT;

	return EOK;
}

/** Processes the received IP packet.
 *
 * Fills set header fields.
 * Returns the prefixed IP header length.
 *
 * @param[in] packet	The received packet.
 * @param[out] protocol	The transport protocol. May be NULL if not desired.
 * @param[out] ttl	The time to live counter. May be NULL if not desired.
 * @param[out] tos	The type of service. May be NULL if not desired.
 * @param[out] dont_fragment The value indicating whether the fragmentation is
 *			disabled. May be NULL if not desired.
 * @param[out] ipopt_length The IP options length in bytes. May be NULL if not
 *			desired.
 * @return		The prefixed IP header length in bytes on success.
 * @return		ENOMEM if the packet is too short to contain the IP
 *			header.
 */
int
ip_client_process_packet(packet_t *packet, ip_protocol_t *protocol,
    ip_ttl_t *ttl, ip_tos_t *tos, int *dont_fragment, size_t *ipopt_length)
{
	ip_header_t *header;

	header = (ip_header_t *) packet_get_data(packet);
	if (!header || (packet_get_data_length(packet) < sizeof(ip_header_t)))
		return ENOMEM;

	if (protocol)
		*protocol = header->protocol;
	if (ttl)
		*ttl = header->ttl;
	if (tos)
		*tos = header->tos;
	if (dont_fragment)
		*dont_fragment = header->flags & IPFLAG_DONT_FRAGMENT;
	if (ipopt_length) {
		*ipopt_length = IP_HEADER_LENGTH(header) - sizeof(ip_header_t);
		return sizeof(ip_header_t);
	} else {
		return IP_HEADER_LENGTH(header);
	}
}

/** Updates the IPv4 pseudo header data length field.
 *
 * @param[in,out] header The IPv4 pseudo header to be updated.
 * @param[in] headerlen	The length of the IP pseudo header in bytes.
 * @param[in] data_length The data length to be set.
 * @return		EOK on success.
 * @return		EBADMEM if the header parameter is NULL.
 * @return		EINVAL if the headerlen parameter is not IPv4 pseudo
 *			header length.
 */
int
ip_client_set_pseudo_header_data_length(void *header, size_t headerlen,
    size_t data_length)
{
	ipv4_pseudo_header_t *header_in;

	if (!header)
		return EBADMEM;

	if (headerlen == sizeof(ipv4_pseudo_header_t)) {
		header_in = (ipv4_pseudo_header_t *) header;
		header_in->data_length = htons(data_length);
		return EOK;
	// TODO IPv6
	} else {
		return EINVAL;
	}
}

/** @}
 */