genode/repos/os/include/net/ethernet.h
Martin Stein 373134c4e7 net: safer access to packet data
Replace packet method 'T *data' by the new methods 'T &reinterpret_data'
for parsing or modifying existing sub-protocol packets and 'T
&construct_at_data' for composing a new sub-protocol packet. This has
the advantage that, when composing a new packet, the default constructor
that zero-fills the packet is always called first.

Fixes #2751
2018-05-03 15:31:54 +02:00

149 lines
3.2 KiB
C++

/*
* \brief Ethernet protocol
* \author Stefan Kalkowski
* \date 2010-08-19
*/
/*
* Copyright (C) 2010-2017 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__ETHERNET_H_
#define _NET__ETHERNET_H_
/* Genode includes */
#include <base/exception.h>
#include <util/string.h>
#include <util/construct_at.h>
#include <util/endian.h>
#include <net/mac_address.h>
namespace Net
{
class Ethernet_frame;
template <Genode::size_t DATA_SIZE>
class Ethernet_frame_sized;
}
/**
* Data layout of this class conforms to the Ethernet II frame
* (IEEE 802.3).
*
* Ethernet-frame-header-format:
*
* ----------------------------------------------------------
* | destination mac address | source mac address | ethertype |
* | 6 bytes | 6 bytes | 2 bytes |
* ----------------------------------------------------------
*/
class Net::Ethernet_frame
{
public:
enum Size {
ADDR_LEN = 6, /* MAC address length in bytes */
};
static Mac_address broadcast() { return Mac_address((Genode::uint8_t)0xff); }
private:
Genode::uint8_t _dst[ADDR_LEN]; /* destination mac address */
Genode::uint8_t _src[ADDR_LEN]; /* source mac address */
Genode::uint16_t _type; /* encapsulated protocol */
unsigned _data[0]; /* encapsulated data */
public:
enum { MIN_SIZE = 64 };
/**
* Id representing encapsulated protocol.
*/
enum class Type : Genode::uint16_t {
IPV4 = 0x0800,
ARP = 0x0806,
};
struct Bad_data_type : Genode::Exception { };
template <typename T> T const &data(Genode::size_t data_size) const
{
if (data_size < sizeof(T)) {
throw Bad_data_type();
}
return *(T const *)(_data);
}
template <typename T> T &data(Genode::size_t data_size)
{
if (data_size < sizeof(T)) {
throw Bad_data_type();
}
return *(T *)(_data);
}
template <typename T, typename SIZE_GUARD>
T &construct_at_data(SIZE_GUARD &size_guard)
{
size_guard.add(sizeof(T));
return *Genode::construct_at<T>(_data);
}
/***************
** Accessors **
***************/
Mac_address dst() const { return Mac_address((void *)_dst); }
Mac_address src() const { return Mac_address((void *)_src); }
Type type() const { return (Type)host_to_big_endian(_type); }
void dst(Mac_address v) { v.copy(&_dst); }
void src(Mac_address v) { v.copy(&_src); }
void type(Type type) { _type = host_to_big_endian((Genode::uint16_t)type); }
/*********
** log **
*********/
void print(Genode::Output &output) const;
} __attribute__((packed));
template <Genode::size_t DATA_SIZE>
class Net::Ethernet_frame_sized : public Ethernet_frame
{
private:
enum {
HS = sizeof(Ethernet_frame),
DS = DATA_SIZE + HS >= MIN_SIZE ? DATA_SIZE : MIN_SIZE - HS,
};
Genode::uint8_t _data[DS];
Genode::uint32_t _checksum;
public:
Ethernet_frame_sized(Mac_address dst_in, Mac_address src_in,
Type type_in)
:
Ethernet_frame(sizeof(Ethernet_frame))
{
dst(dst_in);
src(src_in);
type(type_in);
}
} __attribute__((packed));
#endif /* _NET__ETHERNET_H_ */