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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <AK/Assertions.h>
#include <AK/Endian.h>
#include <AK/IPv4Address.h>
#include <AK/Types.h>
namespace Kernel {
enum class IPv4Protocol : u16 {
ICMP = 1,
TCP = 6,
UDP = 17,
};
enum class IPv4PacketFlags : u16 {
DontFragment = 0x4000,
MoreFragments = 0x2000,
};
NetworkOrdered<u16> internet_checksum(const void*, size_t);
class [[gnu::packed]] IPv4Packet {
public:
u8 version() const { return (m_version_and_ihl >> 4) & 0xf; }
void set_version(u8 version) { m_version_and_ihl = (m_version_and_ihl & 0x0f) | (version << 4); }
u8 dscp_and_ecn() const { return m_dscp_and_ecn; }
void set_dscp_and_ecn(u8 dscp_and_ecn) { m_dscp_and_ecn = dscp_and_ecn; }
u8 internet_header_length() const { return m_version_and_ihl & 0xf; }
void set_internet_header_length(u8 ihl) { m_version_and_ihl = (m_version_and_ihl & 0xf0) | (ihl & 0x0f); }
u16 length() const { return m_length; }
void set_length(u16 length) { m_length = length; }
u16 ident() const { return m_ident; }
void set_ident(u16 ident) { m_ident = ident; }
u8 ttl() const { return m_ttl; }
void set_ttl(u8 ttl) { m_ttl = ttl; }
u8 protocol() const { return m_protocol; }
void set_protocol(u8 protocol) { m_protocol = protocol; }
u16 checksum() const { return m_checksum; }
void set_checksum(u16 checksum) { m_checksum = checksum; }
const IPv4Address& source() const { return m_source; }
void set_source(const IPv4Address& address) { m_source = address; }
const IPv4Address& destination() const { return m_destination; }
void set_destination(const IPv4Address& address) { m_destination = address; }
void* payload() { return this + 1; }
const void* payload() const { return this + 1; }
u16 flags_and_fragment() const { return m_flags_and_fragment; }
u16 fragment_offset() const { return ((u16)m_flags_and_fragment & 0x1fff); }
u16 flags() const { return (((u16)m_flags_and_fragment) & (((u16)IPv4PacketFlags::MoreFragments) | ((u16)IPv4PacketFlags::DontFragment))); }
void set_has_more_fragments(bool more_fragments)
{
if (more_fragments)
m_flags_and_fragment = (u16)m_flags_and_fragment | ((u16)IPv4PacketFlags::MoreFragments);
else
m_flags_and_fragment = (u16)m_flags_and_fragment & ((u16)IPv4PacketFlags::MoreFragments);
}
void set_fragment_offset(u16 offset)
{
m_flags_and_fragment = flags() | (offset & 0x1fff);
}
bool is_a_fragment() const
{
// either has More-Fragments set, or has a fragment offset
return (((u16)m_flags_and_fragment) & ((u16)IPv4PacketFlags::MoreFragments)) || ((u16)m_flags_and_fragment & 0x1fff);
}
u16 payload_size() const { return m_length - sizeof(IPv4Packet); }
NetworkOrdered<u16> compute_checksum() const
{
VERIFY(!m_checksum);
return internet_checksum(this, sizeof(IPv4Packet));
}
private:
u8 m_version_and_ihl { 0 };
u8 m_dscp_and_ecn { 0 };
NetworkOrdered<u16> m_length;
NetworkOrdered<u16> m_ident;
NetworkOrdered<u16> m_flags_and_fragment;
u8 m_ttl { 0 };
NetworkOrdered<u8> m_protocol;
NetworkOrdered<u16> m_checksum;
IPv4Address m_source;
IPv4Address m_destination;
};
static_assert(AssertSize<IPv4Packet, 20>());
inline NetworkOrdered<u16> internet_checksum(const void* ptr, size_t count)
{
u32 checksum = 0;
auto* w = (const u16*)ptr;
while (count > 1) {
checksum += AK::convert_between_host_and_network_endian(*w++);
if (checksum & 0x80000000)
checksum = (checksum & 0xffff) | (checksum >> 16);
count -= 2;
}
while (checksum >> 16)
checksum = (checksum & 0xffff) + (checksum >> 16);
return ~checksum & 0xffff;
}
}
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