Kernel: Implement super simple TCP stack

No SACK support and windows are fixed size

kernel/include/kernel/Networking/NetworkSocket.h

@@ -12,6 +12,7 @@ namespace Kernel
 	enum NetworkProtocol : uint8_t
 	{
 		ICMP = 0x01,
+		TCP = 0x06,
 		UDP = 0x11,
 	};
 

kernel/include/kernel/Networking/TCPSocket.h

@@ -0,0 +1,118 @@
+#pragma once
+
+#include <BAN/Endianness.h>
+#include <kernel/Memory/VirtualRange.h>
+#include <kernel/Networking/NetworkInterface.h>
+#include <kernel/Networking/NetworkSocket.h>
+#include <kernel/Process.h>
+#include <kernel/Semaphore.h>
+
+namespace Kernel
+{
+
+	struct TCPHeader
+	{
+		BAN::NetworkEndian<uint16_t>	src_port		{ 0 };
+		BAN::NetworkEndian<uint16_t>	dst_port		{ 0 };
+		BAN::NetworkEndian<uint32_t>	seq_number		{ 0 };
+		BAN::NetworkEndian<uint32_t>	ack_number		{ 0 };
+		uint8_t							reserved	: 4	{ 0 };
+		uint8_t							data_offset	: 4	{ 0 };
+		uint8_t							fin			: 1	{ 0 };
+		uint8_t							syn			: 1	{ 0 };
+		uint8_t							rst			: 1	{ 0 };
+		uint8_t							psh			: 1	{ 0 };
+		uint8_t							ack			: 1	{ 0 };
+		uint8_t							urg			: 1	{ 0 };
+		uint8_t							ece			: 1	{ 0 };
+		uint8_t							cwr			: 1	{ 0 };
+		BAN::NetworkEndian<uint16_t>	window_size		{ 0 };
+		BAN::NetworkEndian<uint16_t>	checksum		{ 0 };
+		BAN::NetworkEndian<uint16_t>	urgent_pointer	{ 0 };
+		uint8_t							options[0];
+	};
+	static_assert(sizeof(TCPHeader) == 20);
+
+	class TCPSocket final : public NetworkSocket
+	{
+	public:
+		static constexpr size_t m_tcp_options_bytes = 4;
+
+	public:
+		static BAN::ErrorOr<BAN::RefPtr<TCPSocket>> create(NetworkLayer&, ino_t, const TmpInodeInfo&);
+		~TCPSocket();
+
+		virtual NetworkProtocol protocol() const override { return NetworkProtocol::TCP; }
+
+		virtual size_t protocol_header_size() const override { return sizeof(TCPHeader) + m_tcp_options_bytes; }
+		virtual void add_protocol_header(BAN::ByteSpan packet, uint16_t dst_port, PseudoHeader) override;
+
+	protected:
+		virtual void on_close_impl() override;
+
+		virtual BAN::ErrorOr<void> connect_impl(const sockaddr*, socklen_t) override;
+
+		virtual void receive_packet(BAN::ConstByteSpan, const sockaddr_storage& sender) override;
+
+		virtual BAN::ErrorOr<size_t> sendto_impl(BAN::ConstByteSpan message, const sockaddr* address, socklen_t address_len) override;
+		virtual BAN::ErrorOr<size_t> recvfrom_impl(BAN::ByteSpan message, sockaddr* address, socklen_t* address_len) override;
+
+	private:
+		enum class State
+		{
+			Closed = 0,
+			Listen,
+			SynSent,
+			SynReceived,
+			Established,
+			FinWait1,
+			FinWait2,
+			CloseWait,
+			Closing,
+			LastAck,
+			TimeWait,
+		};
+
+		struct WindowInfo
+		{
+			uint32_t					mss				{ 0 };
+			uint16_t					size			{ 0 };
+			uint8_t						scale			{ 0 };
+			uint32_t					start_seq		{ 0 };
+			uint32_t					current_seq		{ 0 };
+			BAN::Atomic<uint32_t>		ack_number		{ 0 };
+			uint32_t					data_size		{ 0 };
+			uint64_t					send_time_ms	{ 0 };
+			BAN::UniqPtr<VirtualRange>	window;
+		};
+
+	private:
+		TCPSocket(NetworkLayer&, ino_t, const TmpInodeInfo&);
+		void process_task();
+
+		void set_connection_as_closed();
+
+	private:
+		State m_state = State::Closed;
+
+		Process* m_process { nullptr };
+
+		uint64_t m_time_wait_start_ms { 0 };
+
+		RecursiveSpinLock	m_lock;
+		Semaphore			m_semaphore;
+
+		BAN::Atomic<bool> m_should_ack { false };
+
+		WindowInfo m_recv_window;
+		WindowInfo m_send_window;
+
+		struct ConnectionInfo
+		{
+			sockaddr_storage	address;
+			socklen_t			address_len;
+		};
+		BAN::Optional<ConnectionInfo> m_connection_info;
+	};
+
+}