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