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genode/repos/os/include/net/dhcp.h
Martin Stein 980f3e9c5c net: use Size_guard for packet-data accessors 
Instead of handing over the maximum available size to the packet data
accessors, hand over a size guard that keeps track of the packets
boundaries.

This commit also moves the size-guard utilitiy header of Ping and NIC
Router to the include/net directory making it a part of the net library.
It applies the new approach to all net-lib users in the basic repositories.

Ping looses its configurability regarding the ICMP data size as this would
require an additional method in the size guard which would be used only by
Ping.

The size guard was also re-worked to fit the fact that a packet can
bring a tail as well as a header (Ethernet).

Issue #2788
2018-05-30 13:36:11 +02:00

480 lines
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/*
* \brief DHCP related definitions
* \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 _DHCP_H_
#define _DHCP_H_
/* Genode */
#include <base/exception.h>
#include <base/stdint.h>
#include <util/construct_at.h>
#include <util/endian.h>
#include <net/ethernet.h>
#include <net/ipv4.h>
#include <net/udp.h>
namespace Net { class Dhcp_packet; }
/**
* Data layout of this class conforms to an DHCP packet (RFC 2131)
*
* DHCP packet layout:
*
* ===================================
* | 1 byte | 1 byte | 1 byte | 1 byte |
* ===================================
* | op | htype | hlen | hops |
* -----------------------------------
* | connection-id (xid) |
* -----------------------------------
* | seconds | flags |
* -----------------------------------
* | client-ip-address |
* -----------------------------------
* | your-ip-address |
* -----------------------------------
* | server-ip-address |
* -----------------------------------
* | relay-agent-ip-address |
* -----------------------------------
* | client-hw-address |
* | (16 bytes) |
* -----------------------------------
* | sname |
* | (64 bytes) |
* -----------------------------------
* | file |
* | (128 bytes) |
* -----------------------------------
* | options |
* | (312 bytes, optional) |
* -----------------------------------
*/
class Net::Dhcp_packet
{
private:
Genode::uint8_t _op;
Genode::uint8_t _htype;
Genode::uint8_t _hlen;
Genode::uint8_t _hops;
Genode::uint32_t _xid;
Genode::uint16_t _secs;
Genode::uint16_t _flags;
Genode::uint8_t _ciaddr[Ipv4_packet::ADDR_LEN];
Genode::uint8_t _yiaddr[Ipv4_packet::ADDR_LEN];
Genode::uint8_t _siaddr[Ipv4_packet::ADDR_LEN];
Genode::uint8_t _giaddr[Ipv4_packet::ADDR_LEN];
Genode::uint8_t _chaddr[16];
Genode::uint8_t _sname[64];
Genode::uint8_t _file[128];
Genode::uint32_t _magic_cookie;
Genode::uint8_t _opts[0];
enum Flag { BROADCAST = 0x80 };
public:
enum class Htype : Genode::uint8_t { ETH = 1 };
enum Opcode {
REQUEST = 1,
REPLY = 2,
INVALID
};
enum Udp_port {
BOOTPS = 67,
BOOTPC = 68
};
void default_magic_cookie() {
_magic_cookie = host_to_big_endian(0x63825363);
}
/*******************************
** Utilities for the options **
*******************************/
/**
* Header of a DHCP option or DHCP option without a payload
*/
class Option
{
private:
Genode::uint8_t _code;
Genode::uint8_t _len;
Genode::uint8_t _value[0];
public:
enum class Code : Genode::uint8_t {
INVALID = 0,
SUBNET_MASK = 1,
ROUTER = 3,
DNS_SERVER = 6,
BROADCAST_ADDR = 28,
REQ_IP_ADDR = 50,
IP_LEASE_TIME = 51,
MSG_TYPE = 53,
SERVER = 54,
PARAM_REQ_LIST = 55,
MAX_MSG_SZ = 57,
CLI_ID = 61,
END = 255,
};
Option(Code code, Genode::uint8_t len)
: _code((Genode::uint8_t)code), _len(len) { }
Code code() const { return (Code)_code; }
Genode::uint8_t len() const { return _len; }
/*********
** log **
*********/
void print(Genode::Output &output) const;
} __attribute__((packed));
struct Option_not_found : Genode::Exception
{
Option::Code const code;
Option_not_found(Option::Code code) : code(code) { }
};
/**
* DHCP option that contains a payload of type T
*/
template <typename T>
class Option_tpl : public Option
{
protected:
T _value;
public:
Option_tpl(Code code, T value)
: Option(code, sizeof(T)), _value(value) { }
} __attribute__((packed));
/**
* DHCP option that specifies the IP packet lease time in seconds
*/
struct Ip_lease_time : Option_tpl<Genode::uint32_t>
{
static constexpr Code CODE = Code::IP_LEASE_TIME;
Ip_lease_time(Genode::uint32_t time)
: Option_tpl(CODE, host_to_big_endian(time)) { }
unsigned long value() const { return host_to_big_endian(_value); }
};
/**
* DHCP option to request specific option type values from the server
*/
struct Parameter_request_list : Option
{
static constexpr Code CODE = Code::PARAM_REQ_LIST;
Parameter_request_list(Genode::size_t len) : Option(CODE, len) { }
};
enum class Message_type : Genode::uint8_t {
DISCOVER = 1,
OFFER = 2,
REQUEST = 3,
DECLINE = 4,
ACK = 5,
NAK = 6,
RELEASE = 7,
INFORM = 8
};
/**
* DHCP option that specifies the DHCP message type
*/
struct Message_type_option : Option_tpl<Genode::uint8_t>
{
static constexpr Code CODE = Code::MSG_TYPE;
Message_type_option(Message_type value)
: Option_tpl(CODE, (Genode::uint8_t)value) { }
Message_type value() const { return (Message_type)_value; }
};
/**
* DHCP options that have only one IPv4 address as payload
*/
template <Option::Code _CODE>
struct Ipv4_option : Option_tpl<Genode::uint32_t>
{
static constexpr Code CODE = _CODE;
Ipv4_option(Ipv4_address value)
: Option_tpl(CODE, value.to_uint32_big_endian()) { }
Ipv4_address value() const {
return Ipv4_address::from_uint32_big_endian(_value); }
};
using Dns_server_ipv4 = Ipv4_option<Option::Code::DNS_SERVER>;
using Subnet_mask = Ipv4_option<Option::Code::SUBNET_MASK>;
using Broadcast_addr = Ipv4_option<Option::Code::BROADCAST_ADDR>;
using Router_ipv4 = Ipv4_option<Option::Code::ROUTER>;
using Server_ipv4 = Ipv4_option<Option::Code::SERVER>;
using Requested_addr = Ipv4_option<Option::Code::REQ_IP_ADDR>;
class Client_id
{
private:
Genode::uint8_t _code;
Genode::uint8_t _len;
Genode::uint8_t _value[7];
public:
Client_id(Mac_address value)
: _code((Genode::uint8_t)Option::Code::CLI_ID), _len(7)
{
_value[0] = 1;
_value[1] = value.addr[0];
_value[2] = value.addr[1];
_value[3] = value.addr[2];
_value[4] = value.addr[3];
_value[5] = value.addr[4];
_value[6] = value.addr[5];
}
Genode::uint8_t code() const { return _code; }
Genode::uint8_t len() const { return _len; }
} __attribute__((packed));
struct Max_msg_size : Option_tpl<Genode::uint16_t>
{
static constexpr Code CODE = Code::MAX_MSG_SZ;
Max_msg_size(Genode::uint16_t size)
: Option_tpl(CODE, host_to_big_endian(size)) { }
};
/**
* DHCP option that marks the end of an options field
*/
struct Options_end : Option
{
static constexpr Code CODE = Code::END;
Options_end() : Option(CODE, 0) { }
};
/**
* Utility to append individual options to an existing DHCP packet
*
* \param SIZE_GUARD guard that may limit the options list size
*
* Overwrites existing options if any!
*/
template <typename SIZE_GUARD>
class Options_aggregator
{
private:
Genode::addr_t _base;
SIZE_GUARD &_size_guard;
public:
class Parameter_request_list_data
{
private:
Genode::uint8_t *const _base;
Genode::size_t _size { 0 };
SIZE_GUARD &_size_guard;
public:
Parameter_request_list_data(Genode::uint8_t *base,
SIZE_GUARD &size_guard)
:
_base { base },
_size_guard { size_guard }
{ }
template <typename OPTION>
void append_param_req()
{
_size_guard.consume_head(sizeof(_base[0]));
_base[_size] = (Genode::uint8_t)OPTION::CODE;
_size++;
}
Genode::size_t size() const { return _size; }
};
Options_aggregator(Dhcp_packet &packet,
SIZE_GUARD &size_guard)
:
_base((Genode::addr_t)packet.opts()),
_size_guard(size_guard)
{ }
template <typename OPTION, typename... ARGS>
void append_option(ARGS &&... args)
{
_size_guard.consume_head(sizeof(OPTION));
Genode::construct_at<OPTION>((void *)_base,
static_cast<ARGS &&>(args)...);
_base += sizeof(OPTION);
}
template <typename INIT_DATA>
void append_param_req_list(INIT_DATA && init_data)
{
_size_guard.consume_head(sizeof(Parameter_request_list));
Parameter_request_list_data
data((Genode::uint8_t *)(_base + sizeof(Parameter_request_list)),
_size_guard);
init_data(data);
Genode::construct_at<Parameter_request_list>((void *)_base,
data.size());
_base += sizeof(Parameter_request_list) + data.size();
}
};
/*
* Call 'functor' of type 'FUNC' for each option (except END options)
*/
template <typename FUNC>
void for_each_option(FUNC && functor) const
{
for (unsigned i = 0; ; ) {
Option &opt = *(Option*)&_opts[i];
if (opt.code() == Option::Code::INVALID ||
opt.code() == Option::Code::END)
{
return;
}
functor(opt);
i += 2 + opt.len();
}
}
/*
* Find and return option of given type 'T'
*
* \throw Option_not_found
*/
template <typename T>
T &option()
{
void *ptr = &_opts;
while (true) {
Option &opt = *reinterpret_cast<Option *>(ptr);
if (opt.code() == Option::Code::INVALID ||
opt.code() == Option::Code::END)
{
throw Option_not_found(T::CODE);
}
if (opt.code() == T::CODE) {
return *reinterpret_cast<T *>(ptr);
}
ptr = (void *)((Genode::addr_t)ptr + sizeof(opt) + opt.len());
}
}
/***************
** Accessors **
***************/
Genode::uint8_t op() const { return _op; }
Htype htype() const { return (Htype)_htype; }
Genode::uint8_t hlen() const { return _hlen; }
Genode::uint8_t hops() const { return _hops; }
Genode::uint32_t xid() const { return host_to_big_endian(_xid); }
Genode::uint16_t secs() const { return host_to_big_endian(_secs); }
bool broadcast() const { return _flags & BROADCAST; }
Ipv4_address ciaddr() const { return Ipv4_address((void *)_ciaddr); }
Ipv4_address yiaddr() const { return Ipv4_address((void *)_yiaddr); }
Ipv4_address siaddr() const { return Ipv4_address((void *)_siaddr); }
Ipv4_address giaddr() const { return Ipv4_address((void *)_giaddr); }
Mac_address client_mac() const { return Mac_address((void *)&_chaddr); }
char const *server_name() const { return (char const *)&_sname; }
char const *file() const { return (char const *)&_file; }
Genode::uint32_t magic_cookie() const { return host_to_big_endian(_magic_cookie); }
Genode::uint16_t flags() const { return host_to_big_endian(_flags); }
void *opts() const { return (void *)_opts; }
void flags(Genode::uint16_t v) { _flags = host_to_big_endian(v); }
void file(const char* v) { Genode::memcpy(_file, v, sizeof(_file)); }
void op(Genode::uint8_t v) { _op = v; }
void htype(Htype v) { _htype = (Genode::uint8_t)v; }
void hlen(Genode::uint8_t v) { _hlen = v; }
void hops(Genode::uint8_t v) { _hops = v; }
void xid(Genode::uint32_t v) { _xid = host_to_big_endian(v); }
void secs(Genode::uint16_t v) { _secs = host_to_big_endian(v); }
void broadcast(bool v) { _flags = v ? BROADCAST : 0; }
void ciaddr(Ipv4_address v) { v.copy(&_ciaddr); }
void yiaddr(Ipv4_address v) { v.copy(&_yiaddr); }
void siaddr(Ipv4_address v) { v.copy(&_siaddr); }
void giaddr(Ipv4_address v) { v.copy(&_giaddr); }
void client_mac(Mac_address v) { v.copy(&_chaddr); }
/*************************
** Convenience methods **
*************************/
static bool is_dhcp(Udp_packet const *udp)
{
return ((udp->src_port() == Port(Dhcp_packet::BOOTPC) ||
udp->src_port() == Port(Dhcp_packet::BOOTPS)) &&
(udp->dst_port() == Port(Dhcp_packet::BOOTPC) ||
udp->dst_port() == Port(Dhcp_packet::BOOTPS)));
}
/*********
** log **
*********/
void print(Genode::Output &output) const;
} __attribute__((packed));
#endif /* _DHCP_H_ */
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