feat: add ethernet & TCP/IP stack

kernel/src/Net/Tcp.hpp

@@ -0,0 +1,80 @@
+/*
+    * Tcp.hpp
+    * Transmission Control Protocol
+    * Copyright (c) 2025 Daniel Hammer
+*/
+
+#pragma once
+#include <cstdint>
+#include <CppLib/Spinlock.hpp>
+
+namespace Net::Tcp {
+
+    constexpr uint16_t HEADER_SIZE = 20; // Without options
+
+    // TCP flags
+    constexpr uint8_t FLAG_FIN = 0x01;
+    constexpr uint8_t FLAG_SYN = 0x02;
+    constexpr uint8_t FLAG_RST = 0x04;
+    constexpr uint8_t FLAG_PSH = 0x08;
+    constexpr uint8_t FLAG_ACK = 0x10;
+
+    struct Header {
+        uint16_t SrcPort;
+        uint16_t DstPort;
+        uint32_t SeqNum;
+        uint32_t AckNum;
+        uint8_t  DataOffset; // Upper 4 bits = offset in 32-bit words
+        uint8_t  Flags;
+        uint16_t Window;
+        uint16_t Checksum;
+        uint16_t UrgentPtr;
+    } __attribute__((packed));
+
+    // TCP connection states
+    enum class State {
+        Closed,
+        Listen,
+        SynSent,
+        SynReceived,
+        Established,
+        FinWait1,
+        FinWait2,
+        CloseWait,
+        LastAck,
+        TimeWait
+    };
+
+    // Opaque connection handle
+    struct Connection;
+
+    // Initialize the TCP subsystem
+    void Initialize();
+
+    // Handle an incoming TCP segment (called by IPv4 layer)
+    void OnPacketReceived(uint32_t srcIp, uint32_t dstIp, const uint8_t* data, uint16_t length);
+
+    // Listen on a port. Returns a connection handle in Listen state.
+    Connection* Listen(uint16_t port);
+
+    // Accept an incoming connection on a listening socket.
+    // Blocks until a connection arrives. Returns a new connection in Established state.
+    Connection* Accept(Connection* listener);
+
+    // Actively connect to a remote host:port. Returns connection in Established state or nullptr.
+    Connection* Connect(uint32_t destIp, uint16_t destPort, uint16_t srcPort);
+
+    // Send data on an established connection. Returns number of bytes sent.
+    int Send(Connection* conn, const uint8_t* data, uint16_t length);
+
+    // Receive data from an established connection. Returns number of bytes received.
+    // Blocks until data is available or connection is closed.
+    int Receive(Connection* conn, uint8_t* buffer, uint16_t bufferSize);
+
+    // Close a TCP connection gracefully
+    void Close(Connection* conn);
+
+    // Get the state of a connection
+    State GetState(Connection* conn);
+
+}