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aff4d22de9
When the MSS option header is missing the default maximum segment size is 536 which results in lots of very small TCP packets that NetworkTask has to handle. This adds the MSS option header to outbound TCP SYN packets and sets it to an appropriate value depending on the interface's MTU. Note that we do not currently do path MTU discovery so this could cause problems when hops don't fragment packets properly.
98 lines
2.8 KiB
C++
98 lines
2.8 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 <Kernel/Net/IPv4.h>
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namespace Kernel {
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struct TCPFlags {
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enum : u16 {
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FIN = 0x01,
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SYN = 0x02,
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RST = 0x04,
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PUSH = 0x08,
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ACK = 0x10,
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URG = 0x20
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};
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};
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class [[gnu::packed]] TCPOptionMSS {
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public:
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TCPOptionMSS(u16 value)
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: m_value(value)
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{
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}
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u16 value() const { return m_value; }
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private:
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u8 m_option_kind { 0x02 };
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u8 m_option_length { sizeof(TCPOptionMSS) };
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NetworkOrdered<u16> m_value;
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};
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static_assert(sizeof(TCPOptionMSS) == 4);
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class [[gnu::packed]] TCPPacket {
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public:
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TCPPacket() = default;
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~TCPPacket() = default;
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size_t header_size() const { return data_offset() * sizeof(u32); }
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u16 source_port() const { return m_source_port; }
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void set_source_port(u16 port) { m_source_port = port; }
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u16 destination_port() const { return m_destination_port; }
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void set_destination_port(u16 port) { m_destination_port = port; }
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u32 sequence_number() const { return m_sequence_number; }
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void set_sequence_number(u32 number) { m_sequence_number = number; }
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u32 ack_number() const { return m_ack_number; }
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void set_ack_number(u32 number) { m_ack_number = number; }
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u16 flags() const { return m_flags_and_data_offset & 0x1ff; }
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void set_flags(u16 flags) { m_flags_and_data_offset = (m_flags_and_data_offset & ~0x1ff) | (flags & 0x1ff); }
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bool has_syn() const { return flags() & TCPFlags::SYN; }
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bool has_ack() const { return flags() & TCPFlags::ACK; }
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bool has_fin() const { return flags() & TCPFlags::FIN; }
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bool has_rst() const { return flags() & TCPFlags::RST; }
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u8 data_offset() const { return (m_flags_and_data_offset & 0xf000) >> 12; }
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void set_data_offset(u16 data_offset) { m_flags_and_data_offset = (m_flags_and_data_offset & ~0xf000) | data_offset << 12; }
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u16 window_size() const { return m_window_size; }
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void set_window_size(u16 window_size) { m_window_size = window_size; }
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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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u16 urgent() const { return m_urgent; }
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void set_urgent(u16 urgent) { m_urgent = urgent; }
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const void* payload() const { return ((const u8*)this) + header_size(); }
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void* payload() { return ((u8*)this) + header_size(); }
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private:
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NetworkOrdered<u16> m_source_port;
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NetworkOrdered<u16> m_destination_port;
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NetworkOrdered<u32> m_sequence_number;
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NetworkOrdered<u32> m_ack_number;
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NetworkOrdered<u16> m_flags_and_data_offset;
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NetworkOrdered<u16> m_window_size;
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NetworkOrdered<u16> m_checksum;
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NetworkOrdered<u16> m_urgent;
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};
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static_assert(sizeof(TCPPacket) == 20);
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}
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