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Kernel: Add support for TCP window size scaling

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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.
This commit is contained in:
Idan Horowitz 2023-12-26 21:05:15 +02:00 • committed by Andreas Kling
parent 2c51ff763b
commit 785c9d5c2b
6 changed files with 124 additions and 14 deletions
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19
Kernel/Net/NetworkTask.cpp
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@ -430,6 +430,19 @@ void handle_tcp(IPv4Packet const& ipv4_packet, UnixDateTime const& packet_timest
dbgln_if(TCP_DEBUG, "handle_tcp: got socket {}; state={}", socket->tuple().to_string(), TCPSocket::to_string(socket->state()));
socket->receive_tcp_packet(tcp_packet, ipv4_packet.payload_size());
Optional<u8> send_window_scale;
if (tcp_packet.has_syn()) {
tcp_packet.for_each_option([&send_window_scale](auto const& option) {
if (option.kind() != TCPOptionKind::WindowScale)
return;
if (option.length() != sizeof(TCPOptionWindowScale))
return;
auto scale = static_cast<TCPOptionWindowScale const&>(option).value();
if (scale > 14)
return; // Maximum allowed as per RFC7323
send_window_scale = scale;
});
}
switch (socket->state()) {
case TCPSocket::State::Closed:
@ -459,6 +472,8 @@ void handle_tcp(IPv4Packet const& ipv4_packet, UnixDateTime const& packet_timest
client->set_ack_number(tcp_packet.sequence_number() + payload_size + 1);
[[maybe_unused]] auto rc2 = client->send_tcp_packet(TCPFlags::SYN | TCPFlags::ACK);
client->set_state(TCPSocket::State::SynReceived);
if (send_window_scale.has_value())
client->set_send_window_scale(*send_window_scale);
return;
}
default:
@ -472,6 +487,8 @@ void handle_tcp(IPv4Packet const& ipv4_packet, UnixDateTime const& packet_timest
socket->set_ack_number(tcp_packet.sequence_number() + payload_size + 1);
(void)socket->send_tcp_packet(TCPFlags::SYN | TCPFlags::ACK);
socket->set_state(TCPSocket::State::SynReceived);
if (send_window_scale.has_value())
socket->set_send_window_scale(*send_window_scale);
return;
case TCPFlags::ACK | TCPFlags::SYN:
socket->set_ack_number(tcp_packet.sequence_number() + payload_size + 1);
@ -479,6 +496,8 @@ void handle_tcp(IPv4Packet const& ipv4_packet, UnixDateTime const& packet_timest
socket->set_state(TCPSocket::State::Established);
socket->set_setup_state(Socket::SetupState::Completed);
socket->set_connected(true);
if (send_window_scale.has_value())
socket->set_send_window_scale(*send_window_scale);
return;
case TCPFlags::ACK | TCPFlags::FIN:
socket->set_ack_number(tcp_packet.sequence_number() + payload_size + 1);