genode/repos/os/include/net/internet_checksum.h

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/*
* \brief Computing the Internet Checksum (conforms to RFC 1071)
* \author Martin Stein
* \date 2018-03-23
*/
/*
* Copyright (C) 2018 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU Affero General Public License version 3.
*/
#ifndef _NET__INTERNET_CHECKSUM_H_
#define _NET__INTERNET_CHECKSUM_H_
/* Genode includes */
#include <net/ipv4.h>
#include <base/stdint.h>
namespace Net {
/**
* This struct helps avoiding the following compiler warning when using
* the internet checksum functions on packet classes (like
* Net::Ipv4_packet):
*
* warning: converting a packed Net::[PACKET_CLASS] pointer
* (alignment 1) to a const uint16_t {aka const short
* unsigned int} pointer (alignment 2) may result in an
* unaligned pointer value
*
* Apparently, the 'packed' attribute normally used on packet classes sets
* the alignment of the packet class to 1. However, for the purpose of the
* internet-checksum functions, we can assume that the packet data has no
* alignment. This is expressed by casting the packet-object pointer to a
* Packed_uint16 pointer instead of a uint16_t pointer.
*/
struct Packed_uint16
{
Genode::uint16_t value;
} __attribute__((packed));
Genode::uint16_t internet_checksum(Packed_uint16 const *addr,
Genode::size_t size,
Genode::addr_t init_sum = 0);
Genode::uint16_t internet_checksum_pseudo_ip(Packed_uint16 const *addr,
Genode::size_t size,
Genode::uint16_t size_be,
Ipv4_packet::Protocol ip_prot,
Ipv4_address &ip_src,
Ipv4_address &ip_dst);
}
#endif /* _NET__INTERNET_CHECKSUM_H_ */