Kernel: TCP functionality (WIP)

Still need to retransmit unacked packets, and we probably need tests for this stuff. But, it works for both serving and receiving TCP packets, hooray!

kernel/CMakeLists.txt

@@ -91,6 +91,7 @@ SET(KERNEL_SRCS
         tasking/BooleanBlocker.cpp
         tasking/PollBlocker.cpp
         tasking/SleepBlocker.cpp
+        tasking/FileBlockers.cpp
         device/VGADevice.cpp
         device/BochsVGADevice.cpp
         device/MultibootVGADevice.cpp
@@ -181,6 +182,7 @@ SET(KERNEL_SRCS
         net/Socket.cpp
         net/IPSocket.cpp
         net/UDPSocket.cpp
+        net/TCPSocket.cpp
         net/Router.cpp)
 
 add_custom_command(

kernel/Result.cpp

@@ -20,6 +20,8 @@
 #include "Result.hpp"
 #include "kernel/kstd/kstdio.h"
 
+const Result Result::Success {0};
+
 Result::Result(int code): _code(code) {
 }
 

kernel/Result.hpp

@@ -21,6 +21,7 @@
 
 #include <kernel/kstd/Arc.h>
 #include <kernel/kstd/kstdio.h>
+#include <kernel/kstd/type_traits.h>
 
 #define TRY(expr) \
 	({ \
@@ -30,9 +31,16 @@
         res.value(); \
     })
 
+#define TRYRES(expr) \
+	({ \
+        auto res = (expr); \
+        if (res.is_error()) \
+            return res; \
+    })
+
 class Result {
 public:
-	static const int Success = 0;
+	static const Result Success;
 
 	explicit Result(int code);
 

kernel/api/ipv4.h

@@ -44,6 +44,18 @@ class __attribute__((packed)) IPv4Address {
 		return m_data < other.m_data;
 	}
 
+	inline constexpr bool operator<=(const IPv4Address& other) const {
+		return m_data <= other.m_data;
+	}
+
+	inline constexpr bool operator>(const IPv4Address& other) const {
+		return m_data > other.m_data;
+	}
+
+	inline constexpr bool operator>=(const IPv4Address& other) const {
+		return m_data >= other.m_data;
+	}
+
 	inline sockaddr_in as_sockaddr(in_port_t port) const {
 		sockaddr_in ret;
 		ret.sin_family = AF_INET;

kernel/api/socket.h

@@ -28,6 +28,15 @@ __DECL_BEGIN
 #define SO_BROADCAST          2
 #define SO_ERROR              3
 
+// shutdown
+#define SHUT_RD   0x1
+#define SHUT_WR   0x2
+#define SHUT_RDWR (SHUT_RD | SHUT_WR)
+
+// flags
+#define SOCK_NONBLOCK   0x1
+#define SOCK_CLOEXEC    0x2
+
 typedef uint16_t sa_family_t;
 typedef uint32_t socklen_t;
 

kernel/api/tcp.h

@@ -0,0 +1,106 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/* Copyright © 2016-2024 Byteduck */
+
+#pragma once
+
+#include "endian.h"
+
+#define TCP_FIN 0x01
+#define TCP_SYN 0x02
+#define TCP_RST 0x04
+#define TCP_PSH 0x08
+#define TCP_ACK 0x10
+#define TCP_URG 0x20
+
+enum TCPOption {
+	End = 0,
+	Nop = 1,
+	MSS = 2,
+	WindowScale = 3,
+	SACKPermit = 4,
+	SACK = 5,
+	Timestamp = 6
+};
+
+struct TCPSegment {
+	BigEndian<uint16_t> source_port;
+	BigEndian<uint16_t> dest_port;
+	BigEndian<uint32_t> sequence;
+	BigEndian<uint32_t> ack;
+	BigEndian<uint16_t> flags_and_offset;
+	BigEndian<uint16_t> window_size;
+	BigEndian<uint16_t> checksum;
+	BigEndian<uint16_t> urgent_pointer;
+	uint8_t data[];
+
+	[[nodiscard]] uint8_t data_offset() const { return (flags_and_offset.val() & 0xf000) >> 12; }
+	void set_data_offset(uint8_t offset) { flags_and_offset = (flags_and_offset & 0xfff) | ((uint16_t) offset) << 12; }
+
+	[[nodiscard]] uint8_t flags() const { return flags_and_offset.val() & 0x01ff; }
+	void set_flags(uint16_t flags) { flags_and_offset = (flags_and_offset & ~0x01ff) | (flags & 0x1ff); }
+
+	[[nodiscard]] const uint8_t* payload() const { return ((const uint8_t*) this) + (data_offset() * sizeof(uint32_t)); }
+	[[nodiscard]] uint8_t* payload() { return ((uint8_t*) this) + (data_offset() * sizeof(uint32_t)); }
+
+	inline BigEndian<uint16_t> calculate_checksum(const IPv4Address& src, const IPv4Address& dest, size_t payload_size) {
+		union PseudoHeader {
+			struct __attribute__((packed)) {
+				IPv4Address src;
+				IPv4Address dest;
+				uint8_t zero;
+				uint8_t proto;
+				BigEndian<uint16_t> payload_size;
+			} data;
+			uint16_t raw[6] = {0};
+		};
+		static_assert(sizeof(PseudoHeader::data) == sizeof(PseudoHeader::raw));
+
+		PseudoHeader pheader = {
+			.data = {
+				.src = src,
+				.dest = dest,
+				.zero = 0,
+				.proto = IPv4Proto::TCP,
+				.payload_size = data_offset() * sizeof(uint32_t) + payload_size
+			}
+		};
+
+		uint32_t sum = 0;
+
+		// Checksum of pseudo header
+		auto* ptr = (uint16_t*) pheader.raw;
+		for (size_t i = 0; i < sizeof(pheader) / sizeof(uint16_t); i++) {
+			sum += as_big_endian(ptr[i]);
+			if (sum > 0xffff)
+				sum = (sum >> 16) + (sum & 0xffff);
+		}
+
+		// Checksum of segment header
+		const void* selfptr = this; // Necessary to suppress alignment errors
+		ptr = (uint16_t*) selfptr;
+		for (size_t i = 0; i < (data_offset() * sizeof(uint32_t)) / sizeof(uint16_t); i++) {
+			sum += as_big_endian(ptr[i]);
+			if (sum > 0xffff)
+				sum = (sum >> 16) + (sum & 0xffff);
+		}
+
+		// Checksum of payload
+		ptr = (uint16_t*) payload();
+		for (size_t i = 0; i < payload_size / sizeof(uint16_t); i++) {
+			sum += as_big_endian(ptr[i]);
+			if (sum > 0xffff)
+				sum = (sum >> 16) + (sum & 0xffff);
+		}
+
+		// Pad
+		if (payload_size % 2 != 0) {
+			sum += ((uint32_t) payload()[payload_size - 1]) << 8;
+			if (sum > 0xffff)
+				sum = (sum >> 16) + (sum & 0xffff);
+		}
+
+		return ~(sum & 0xffff);
+	}
+} __attribute__((packed));
+
+static_assert(sizeof(TCPSegment) == 20);

kernel/net/E1000Adapter.cpp

@@ -112,7 +112,7 @@
 #define INT_RXO     0x40 // Receiver Overrun
 #define INT_RXT0    0x80 // Receiver Timer Interrupt
 
-#define E1000_DBG true
+#define E1000_DBG false
 
 void E1000Adapter::probe() {
 	PCI::enumerate_devices([](PCI::Address address, PCI::ID id, uint16_t type, void* dataPtr) {
@@ -266,15 +266,12 @@ void E1000Adapter::receive() {
 		ASSERT(desc.length <= rx_buffer_size);
 		KLog::dbg_if<E1000_DBG>("E1000", "Received packet ({} bytes)", desc.length);
 		desc.status = 0;
-		{
-			TaskManager::ScopedCritical crit;
-			receive_bytes(KernelPointer((uint8_t*) (m_rx_buffer_region->start() + (rx_buffer_size * cur_desc))), desc.length);
-		}
+		receive_bytes({(uint8_t*) (m_rx_buffer_region->start() + (rx_buffer_size * cur_desc)), desc.length}, desc.length);
 		m_window.out32(REG_RXDESCTAIL, cur_desc);
 	}
 }
 
-void E1000Adapter::send_bytes(SafePointer<uint8_t> bytes, size_t count) {
+void E1000Adapter::send_bytes(const ReadableBytes& bytes, size_t count) {
 	ASSERT(count <= tx_buffer_size);
 	PCI::disable_interrupt(m_pci_address);
 	auto cur_tx_desc = m_window.in32(REG_TXDESCTAIL) % num_tx_descriptors;

kernel/net/E1000Adapter.h

@@ -15,7 +15,7 @@ class E1000Adapter: public NetworkAdapter, IRQHandler {
 
 protected:
 	void handle_irq(IRQRegisters *regs) override;
-	void send_bytes(SafePointer<uint8_t> bytes, size_t count) override;
+	void send_bytes(const ReadableBytes &bytes, size_t count) override;
 
 private:
 	explicit E1000Adapter(PCI::Address addr);

kernel/net/ICMP.h

@@ -3,7 +3,7 @@
 
 #pragma once
 
-enum ICMPType {
+enum class ICMPType {
 	EchoReply = 0,
 	DestinationUnreachable = 3,
 	SourceQuench = 4,