ladybird/Kernel/Net/TCP.h
Idan Horowitz 785c9d5c2b Kernel: Add support for TCP window size scaling
This should allow us to eventually properly saturate high-bandwidth
network links when using TCP, once other nonoptimal parts of our
network stack are improved.
2023-12-26 21:36:49 +01:00

158 lines
4.4 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#pragma once
#include <Kernel/Net/IPv4.h>
namespace Kernel {
struct TCPFlags {
enum : u16 {
FIN = 0x01,
SYN = 0x02,
RST = 0x04,
PSH = 0x08,
ACK = 0x10,
URG = 0x20
};
};
enum class TCPOptionKind : u8 {
End = 0,
Nop = 1,
MSS = 2,
WindowScale = 3,
SACKPermitted = 4,
SACK = 5,
Timestamp = 6,
};
class [[gnu::packed]] TCPOption {
public:
TCPOptionKind kind() const { return m_kind; }
u8 length() const { return m_length; }
protected:
TCPOption(TCPOptionKind kind, u8 length)
: m_kind(kind)
, m_length(length) {};
private:
TCPOptionKind m_kind { TCPOptionKind::End };
u8 m_length { sizeof(TCPOption) };
};
class [[gnu::packed]] TCPOptionMSS : public TCPOption {
public:
TCPOptionMSS(u16 value)
: TCPOption(TCPOptionKind::MSS, sizeof(TCPOptionMSS))
, m_value(value)
{
}
u16 value() const { return m_value; }
private:
NetworkOrdered<u16> m_value;
};
class [[gnu::packed]] TCPOptionWindowScale : public TCPOption {
public:
TCPOptionWindowScale(u8 value)
: TCPOption(TCPOptionKind::WindowScale, sizeof(TCPOptionWindowScale))
, m_value(value)
{
}
u8 value() const { return m_value; }
private:
NetworkOrdered<u8> m_value;
};
static_assert(AssertSize<TCPOptionMSS, 4>());
class [[gnu::packed]] TCPPacket {
public:
TCPPacket() = default;
~TCPPacket() = default;
size_t header_size() const { return data_offset() * sizeof(u32); }
u16 source_port() const { return m_source_port; }
void set_source_port(u16 port) { m_source_port = port; }
u16 destination_port() const { return m_destination_port; }
void set_destination_port(u16 port) { m_destination_port = port; }
u32 sequence_number() const { return m_sequence_number; }
void set_sequence_number(u32 number) { m_sequence_number = number; }
u32 ack_number() const { return m_ack_number; }
void set_ack_number(u32 number) { m_ack_number = number; }
u16 flags() const { return m_flags_and_data_offset & 0x1ff; }
void set_flags(u16 flags) { m_flags_and_data_offset = (m_flags_and_data_offset & ~0x1ff) | (flags & 0x1ff); }
bool has_syn() const { return flags() & TCPFlags::SYN; }
bool has_ack() const { return flags() & TCPFlags::ACK; }
bool has_fin() const { return flags() & TCPFlags::FIN; }
bool has_rst() const { return flags() & TCPFlags::RST; }
u8 data_offset() const { return (m_flags_and_data_offset & 0xf000) >> 12; }
void set_data_offset(u16 data_offset) { m_flags_and_data_offset = (m_flags_and_data_offset & ~0xf000) | data_offset << 12; }
u16 window_size() const { return m_window_size; }
void set_window_size(u16 window_size) { m_window_size = window_size; }
u16 checksum() const { return m_checksum; }
void set_checksum(u16 checksum) { m_checksum = checksum; }
u16 urgent() const { return m_urgent; }
void set_urgent(u16 urgent) { m_urgent = urgent; }
void const* payload() const { return ((u8 const*)this) + header_size(); }
void* payload() { return ((u8*)this) + header_size(); }
template<typename Callback>
void for_each_option(Callback callback) const
{
auto const* next_option = (u8 const*)this + sizeof(TCPPacket);
auto const* options_end = payload();
while (next_option < options_end) {
if ((size_t)options_end - (size_t)next_option < sizeof(TCPOption))
return; // Not enough space left for another option
auto const* option = (TCPOption const*)next_option;
if (option->kind() == TCPOptionKind::End)
return;
if (option->kind() == TCPOptionKind::Nop) {
next_option += 1;
continue;
}
if (option->length() < sizeof(TCPOption))
return; // minimal option length
callback(*option);
next_option += option->length();
}
}
private:
NetworkOrdered<u16> m_source_port;
NetworkOrdered<u16> m_destination_port;
NetworkOrdered<u32> m_sequence_number;
NetworkOrdered<u32> m_ack_number;
NetworkOrdered<u16> m_flags_and_data_offset;
NetworkOrdered<u16> m_window_size;
NetworkOrdered<u16> m_checksum;
NetworkOrdered<u16> m_urgent;
};
static_assert(AssertSize<TCPPacket, 20>());
}