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8f228e3035
The NIC router used to send an ICMP "Destination Unreachable" packet as response to every unroutable IPv4 packet. However, RFC 1812 section 4.3.2.7 defines certain properties that must be fullfilled by an incoming packet in order to be answered with this type of ICMP. One requirement is that the packet is no IPv4 multicast. This commit prevents sending the mentioned ICMP response for unroutable IPv4 multicasts and instead drops them silently. Fixes #4563
296 lines
9.4 KiB
C++
296 lines
9.4 KiB
C++
/*
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* \brief Internet protocol version 4.
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* \author Stefan Kalkowski
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* \date 2010-08-19
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*/
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/*
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* Copyright (C) 2010-2017 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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#ifndef _IPV4_H_
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#define _IPV4_H_
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/* Genode */
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#include <base/exception.h>
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#include <util/string.h>
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#include <util/token.h>
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#include <util/construct_at.h>
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#include <util/endian.h>
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#include <util/register.h>
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#include <net/netaddress.h>
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#include <net/size_guard.h>
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namespace Genode { class Output; }
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namespace Net {
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enum { IPV4_ADDR_LEN = 4 };
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class Internet_checksum_diff;
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class Ipv4_address;
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class Ipv4_packet;
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static inline Genode::size_t ascii_to(char const *, Net::Ipv4_address &);
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}
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struct Net::Ipv4_address : Network_address<IPV4_ADDR_LEN, '.', false>
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{
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Ipv4_address(Genode::uint8_t value = 0) : Network_address(value) { }
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Ipv4_address(void *src) : Network_address(src) { }
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bool valid() const { return *this != Ipv4_address(); }
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Genode::uint32_t to_uint32_big_endian() const;
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static Ipv4_address from_uint32_big_endian(Genode::uint32_t ip_raw);
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Genode::uint32_t to_uint32_little_endian() const;
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static Ipv4_address from_uint32_little_endian(Genode::uint32_t ip_raw);
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bool is_in_range(Ipv4_address const &first,
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Ipv4_address const &last) const;
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bool is_multicast() const;
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}
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__attribute__((packed));
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/**
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* Data layout of this class conforms to an IPv4 packet (RFC 791)
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*
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* IPv4-header-format:
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*
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* ----------------------------------------------------------------
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* | 0-3 | 4-7 | 8-11 | 12-15 | 16-18 | 19-23 | 24-27 | 28-31 |
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* ----------------------------------------------------------------
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* | version | IHL | service-type | total-length |
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* ----------------------------------------------------------------
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* | identifikation | flags | fragment-offset |
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* ----------------------------------------------------------------
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* | ttl | protocol | header-checksum |
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* ----------------------------------------------------------------
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* | source-ip-address |
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* ----------------------------------------------------------------
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* | destination-ip-address |
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* ----------------------------------------------------------------
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* | options ... |
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* ----------------------------------------------------------------
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*/
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class Net::Ipv4_packet
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{
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public:
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enum Size {
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ADDR_LEN = IPV4_ADDR_LEN, /* Ip address length in bytes */
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};
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static Ipv4_address current() { return Ipv4_address((Genode::uint8_t)0x00); }
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static Ipv4_address broadcast() { return Ipv4_address((Genode::uint8_t)0xff); }
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static Ipv4_address ip_from_string(const char *ip);
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void update_checksum();
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void update_checksum(Internet_checksum_diff const &icd);
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void update_checksum(Internet_checksum_diff const &icd,
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Internet_checksum_diff &caused_icd);
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bool checksum_error() const;
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private:
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/************************
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** IPv4 header fields **
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************************/
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struct Offset_6_u16 : Genode::Register<16>
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{
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struct Fragment_offset : Bitfield<0, 13> { };
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struct Flags : Bitfield<13, 3> { };
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struct More_fragments : Bitfield<13, 1> { };
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struct Dont_fragment : Bitfield<14, 1> { };
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};
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struct Offset_0_u8 : Genode::Register<8>
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{
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struct Ihl : Bitfield<0, 4> { }; /* Internet Header Length */
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struct Version : Bitfield<4, 4> { };
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};
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struct Offset_1_u8 : Genode::Register<8>
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{
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struct Ecn : Bitfield<0, 2> { }; /* Explicit Congestion Notification */
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struct Dscp : Bitfield<2, 6> { }; /* Differentiated Services Code Point */
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};
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Genode::uint8_t _offset_0_u8;
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Genode::uint8_t _offset_1_u8;
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Genode::uint16_t _total_length;
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Genode::uint16_t _identification;
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Genode::uint16_t _offset_6_u16;
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Genode::uint8_t _time_to_live;
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Genode::uint8_t _protocol;
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Genode::uint16_t _checksum;
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Genode::uint8_t _src[ADDR_LEN];
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Genode::uint8_t _dst[ADDR_LEN];
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unsigned _data[0];
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public:
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enum class Protocol : Genode::uint8_t
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{
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ICMP = 1,
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TCP = 6,
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UDP = 17,
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};
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static Ipv4_packet const &cast_from(void const *base,
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Size_guard &size_guard)
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{
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size_guard.consume_head(sizeof(Ipv4_packet));
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return *(Ipv4_packet const *)base;
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}
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template <typename T>
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T const &data(Size_guard &size_guard) const
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{
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size_guard.consume_head(sizeof(T));
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return *(T const *)(_data);
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}
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template <typename T>
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T &data(Size_guard &size_guard)
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{
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size_guard.consume_head(sizeof(T));
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return *(T *)(_data);
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}
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template <typename T, typename SIZE_GUARD>
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T &construct_at_data(SIZE_GUARD &size_guard)
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{
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size_guard.consume_head(sizeof(T));
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return *Genode::construct_at<T>(_data);
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}
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Genode::size_t size(Genode::size_t max_size) const;
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/***************
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** Accessors **
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***************/
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Genode::size_t header_length() const { return Offset_0_u8::Ihl::get(_offset_0_u8); }
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Genode::uint8_t version() const { return Offset_0_u8::Version::get(_offset_0_u8); }
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Genode::uint8_t diff_service() const { return Offset_1_u8::Dscp::get(_offset_1_u8); }
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Genode::uint8_t ecn() const { return Offset_1_u8::Ecn::get(_offset_1_u8); }
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Genode::size_t total_length() const { return host_to_big_endian(_total_length); }
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Genode::uint16_t identification() const { return host_to_big_endian(_identification); }
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Genode::uint8_t flags() const { return (Genode::uint8_t)Offset_6_u16::Flags::get(host_to_big_endian(_offset_6_u16)); }
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bool dont_fragment() const { return Offset_6_u16::Dont_fragment::get(host_to_big_endian(_offset_6_u16)); }
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bool more_fragments() const { return Offset_6_u16::More_fragments::get(host_to_big_endian(_offset_6_u16)); }
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Genode::size_t fragment_offset() const { return Offset_6_u16::Fragment_offset::get(host_to_big_endian(_offset_6_u16)); }
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Genode::uint8_t time_to_live() const { return _time_to_live; }
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Protocol protocol() const { return (Protocol)_protocol; }
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Genode::uint16_t checksum() const { return host_to_big_endian(_checksum); }
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Ipv4_address src() const { return Ipv4_address((void *)&_src); }
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Ipv4_address dst() const { return Ipv4_address((void *)&_dst); }
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void header_length(Genode::size_t v) { Offset_0_u8::Ihl::set(_offset_0_u8, (Offset_0_u8::access_t)v); }
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void version(Genode::uint8_t v) { Offset_0_u8::Version::set(_offset_0_u8, v); }
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void diff_service(Genode::uint8_t v) { Offset_1_u8::Dscp::set(_offset_1_u8, v); }
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void ecn(Genode::uint8_t v) { Offset_1_u8::Ecn::set(_offset_1_u8, v); }
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void diff_service_ecn(Genode::uint8_t v) { _offset_1_u8 = v; }
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void total_length(Genode::size_t v) { _total_length = host_to_big_endian((Genode::uint16_t)v); }
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void identification(Genode::uint16_t v) { _identification = host_to_big_endian(v); }
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void time_to_live(Genode::uint8_t v) { _time_to_live = v; }
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void protocol(Protocol v) { _protocol = (Genode::uint8_t)v; }
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void checksum(Genode::uint16_t checksum) { _checksum = host_to_big_endian(checksum); }
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void src(Ipv4_address v) { v.copy(&_src); }
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void dst(Ipv4_address v) { v.copy(&_dst); }
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void src_big_endian(Genode::uint32_t v) { *(Genode::uint32_t *)&_src = v; }
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void dst_big_endian(Genode::uint32_t v) { *(Genode::uint32_t *)&_dst = v; }
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void flags(Genode::uint8_t v)
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{
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Genode::uint16_t be = host_to_big_endian(_offset_6_u16);
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Offset_6_u16::Flags::set(be, v);
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_offset_6_u16 = host_to_big_endian(be);
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}
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void fragment_offset(Genode::size_t v)
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{
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Genode::uint16_t be = host_to_big_endian(_offset_6_u16);
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Offset_6_u16::Fragment_offset::set(be, (Offset_6_u16::access_t)v);
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_offset_6_u16 = host_to_big_endian(be);
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}
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void dont_fragment(bool v)
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{
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Genode::uint16_t be = host_to_big_endian(_offset_6_u16);
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Offset_6_u16::Dont_fragment::set(be, v);
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_offset_6_u16 = host_to_big_endian(be);
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}
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void more_fragments(bool v)
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{
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Genode::uint16_t be = host_to_big_endian(_offset_6_u16);
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Offset_6_u16::More_fragments::set(be, v);
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_offset_6_u16 = host_to_big_endian(be);
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}
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void src(Ipv4_address v, Internet_checksum_diff &icd);
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void dst(Ipv4_address v, Internet_checksum_diff &icd);
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/*********
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** log **
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*********/
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void print(Genode::Output &output) const;
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} __attribute__((packed));
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Genode::size_t Net::ascii_to(char const *s, Net::Ipv4_address &result)
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{
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using namespace Genode;
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Net::Ipv4_address buf;
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size_t number_idx = 0;
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size_t read_len = 0;
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while (1) {
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/* read the current number, fail if there's no number */
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size_t number_len = ascii_to_unsigned(s, buf.addr[number_idx], 10);
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if (!number_len) {
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return 0; }
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/* update read length and number index */
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read_len += number_len;
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number_idx++;
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/* if we have all numbers, fill result and return read length */
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if (number_idx == sizeof(buf.addr) / sizeof(buf.addr[0])) {
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result = buf;
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return read_len;
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}
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/* as it was not the last number, check for the following dot */
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s += number_len;
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if (*s != '.') {
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return 0; }
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read_len++;
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s++;
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}
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}
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#endif /* _IPV4_H_ */
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