Kernel: Improve syscall handling

Syscalls are now called from a list of function pointers

BAN/include/BAN/Bitcast.h

@@ -0,0 +1,12 @@
+#pragma once
+
+namespace BAN
+{
+
+	template<typename To, typename From>
+	constexpr To bit_cast(const From& from)
+	{
+		return __builtin_bit_cast(To, from);
+	}
+
+}

kernel/CMakeLists.txt

@@ -57,6 +57,7 @@ set(KERNEL_SOURCES
 	kernel/Networking/NetworkInterface.cpp
 	kernel/Networking/NetworkManager.cpp
 	kernel/Networking/NetworkSocket.cpp
+	kernel/Networking/TCPSocket.cpp
 	kernel/Networking/UDPSocket.cpp
 	kernel/Networking/UNIX/Socket.cpp
 	kernel/OpenFileDescriptorSet.cpp
@@ -64,6 +65,7 @@ set(KERNEL_SOURCES
 	kernel/PCI.cpp
 	kernel/PIC.cpp
 	kernel/Process.cpp
+	kernel/Random.cpp
 	kernel/Scheduler.cpp
 	kernel/Semaphore.cpp
 	kernel/SpinLock.cpp

kernel/arch/x86_64/Signal.S

@@ -1,7 +1,5 @@
 .section .userspace, "aw"
 
-#include <sys/syscall.h>
-
 // stack contains
 //    return address
 //    signal number

kernel/include/kernel/Device/DebugDevice.h

@@ -21,6 +21,10 @@ namespace Kernel
 		virtual BAN::ErrorOr<size_t> read_impl(off_t, BAN::ByteSpan) override { return 0; }
 		virtual BAN::ErrorOr<size_t> write_impl(off_t, BAN::ConstByteSpan buffer) override;
 
+		virtual bool can_read_impl() const override { return false; }
+		virtual bool can_write_impl() const override { return true; }
+		virtual bool has_error_impl() const override { return false; }
+
 	private:
 		const dev_t m_rdev;
 	};

kernel/include/kernel/Device/FramebufferDevice.h

@@ -30,6 +30,10 @@ namespace Kernel
 		virtual BAN::ErrorOr<size_t> read_impl(off_t, BAN::ByteSpan) override;
 		virtual BAN::ErrorOr<size_t> write_impl(off_t, BAN::ConstByteSpan) override;
 
+		virtual bool can_read_impl() const override { return true; }
+		virtual bool can_write_impl() const override { return true; }
+		virtual bool has_error_impl() const override { return false; }
+
 	private:
 		FramebufferDevice(mode_t mode, uid_t uid, gid_t gid, dev_t rdev, paddr_t paddr, uint32_t width, uint32_t height, uint32_t pitch, uint8_t bpp);
 		BAN::ErrorOr<void> initialize();

kernel/include/kernel/Device/NullDevice.h

@@ -23,6 +23,10 @@ namespace Kernel
 		virtual BAN::ErrorOr<size_t> read_impl(off_t, BAN::ByteSpan) override { return 0; }
 		virtual BAN::ErrorOr<size_t> write_impl(off_t, BAN::ConstByteSpan buffer) override { return buffer.size(); };
 
+		virtual bool can_read_impl() const override { return false; }
+		virtual bool can_write_impl() const override { return true; }
+		virtual bool has_error_impl() const override { return false; }
+
 	private:
 		const dev_t m_rdev;
 	};

kernel/include/kernel/Device/ZeroDevice.h

@@ -21,6 +21,10 @@ namespace Kernel
 		virtual BAN::ErrorOr<size_t> read_impl(off_t, BAN::ByteSpan) override;
 		virtual BAN::ErrorOr<size_t> write_impl(off_t, BAN::ConstByteSpan buffer) override { return buffer.size(); };
 
+		virtual bool can_read_impl() const override { return true; }
+		virtual bool can_write_impl() const override { return false; }
+		virtual bool has_error_impl() const override { return false; }
+
 	private:
 		const dev_t m_rdev;
 	};

kernel/include/kernel/FS/Ext2/Inode.h

@@ -43,6 +43,10 @@ namespace Kernel
 		virtual BAN::ErrorOr<void> truncate_impl(size_t) override;
 		virtual BAN::ErrorOr<void> chmod_impl(mode_t) override;
 
+		virtual bool can_read_impl() const override { return true; }
+		virtual bool can_write_impl() const override { return true; }
+		virtual bool has_error_impl() const override { return false; }
+
 	private:
 		// Returns maximum number of data blocks in use
 		// NOTE: the inode might have more blocks than what this suggests if it has been shrinked

kernel/include/kernel/FS/Inode.h

@@ -104,8 +104,8 @@ namespace Kernel
 		BAN::ErrorOr<void> bind(const sockaddr* address, socklen_t address_len);
 		BAN::ErrorOr<void> connect(const sockaddr* address, socklen_t address_len);
 		BAN::ErrorOr<void> listen(int backlog);
-		BAN::ErrorOr<size_t> sendto(const sys_sendto_t*);
-		BAN::ErrorOr<size_t> recvfrom(sys_recvfrom_t*);
+		BAN::ErrorOr<size_t> sendto(BAN::ConstByteSpan message, const sockaddr* address, socklen_t address_len);
+		BAN::ErrorOr<size_t> recvfrom(BAN::ByteSpan buffer, sockaddr* address, socklen_t* address_len);
 
 		// General API
 		BAN::ErrorOr<size_t> read(off_t, BAN::ByteSpan buffer);
@@ -113,7 +113,11 @@ namespace Kernel
 		BAN::ErrorOr<void> truncate(size_t);
 		BAN::ErrorOr<void> chmod(mode_t);
 		BAN::ErrorOr<void> chown(uid_t, gid_t);
-		bool has_data() const;
+
+		// Select/Non blocking API
+		bool can_read() const;
+		bool can_write() const;
+		bool has_error() const;
 
 		BAN::ErrorOr<long> ioctl(int request, void* arg);
 
@@ -131,12 +135,12 @@ namespace Kernel
 		virtual BAN::ErrorOr<BAN::String> link_target_impl()				{ return BAN::Error::from_errno(ENOTSUP); }
 
 		// Socket API
-		virtual BAN::ErrorOr<long> accept_impl(sockaddr*, socklen_t*)		{ return BAN::Error::from_errno(ENOTSUP); }
-		virtual BAN::ErrorOr<void> connect_impl(const sockaddr*, socklen_t)	{ return BAN::Error::from_errno(ENOTSUP); }
-		virtual BAN::ErrorOr<void> listen_impl(int)							{ return BAN::Error::from_errno(ENOTSUP); }
-		virtual BAN::ErrorOr<void> bind_impl(const sockaddr*, socklen_t)	{ return BAN::Error::from_errno(ENOTSUP); }
-		virtual BAN::ErrorOr<size_t> sendto_impl(const sys_sendto_t*)		{ return BAN::Error::from_errno(ENOTSUP); }
-		virtual BAN::ErrorOr<size_t> recvfrom_impl(sys_recvfrom_t*)			{ return BAN::Error::from_errno(ENOTSUP); }
+		virtual BAN::ErrorOr<long> accept_impl(sockaddr*, socklen_t*)								{ return BAN::Error::from_errno(ENOTSUP); }
+		virtual BAN::ErrorOr<void> connect_impl(const sockaddr*, socklen_t)							{ return BAN::Error::from_errno(ENOTSUP); }
+		virtual BAN::ErrorOr<void> listen_impl(int)													{ return BAN::Error::from_errno(ENOTSUP); }
+		virtual BAN::ErrorOr<void> bind_impl(const sockaddr*, socklen_t)							{ return BAN::Error::from_errno(ENOTSUP); }
+		virtual BAN::ErrorOr<size_t> sendto_impl(BAN::ConstByteSpan, const sockaddr*, socklen_t)	{ return BAN::Error::from_errno(ENOTSUP); }
+		virtual BAN::ErrorOr<size_t> recvfrom_impl(BAN::ByteSpan, sockaddr*, socklen_t*)				{ return BAN::Error::from_errno(ENOTSUP); }
 
 		// General API
 		virtual BAN::ErrorOr<size_t> read_impl(off_t, BAN::ByteSpan)		{ return BAN::Error::from_errno(ENOTSUP); }
@@ -144,7 +148,11 @@ namespace Kernel
 		virtual BAN::ErrorOr<void> truncate_impl(size_t)					{ return BAN::Error::from_errno(ENOTSUP); }
 		virtual BAN::ErrorOr<void> chmod_impl(mode_t)						{ return BAN::Error::from_errno(ENOTSUP); }
 		virtual BAN::ErrorOr<void> chown_impl(uid_t, gid_t)					{ return BAN::Error::from_errno(ENOTSUP); }
-		virtual bool has_data_impl() const { dwarnln("nonblock not supported"); return true; }
+
+		// Select/Non blocking API
+		virtual bool can_read_impl() const = 0;
+		virtual bool can_write_impl() const = 0;
+		virtual bool has_error_impl() const = 0;
 
 		virtual BAN::ErrorOr<long> ioctl_impl(int request, void* arg)		{ return BAN::Error::from_errno(ENOTSUP); }
 

kernel/include/kernel/FS/Pipe.h

@@ -34,6 +34,10 @@ namespace Kernel
 		virtual BAN::ErrorOr<size_t> read_impl(off_t, BAN::ByteSpan) override;
 		virtual BAN::ErrorOr<size_t> write_impl(off_t, BAN::ConstByteSpan) override;
 
+		virtual bool can_read_impl() const override { return !m_buffer.empty(); }
+		virtual bool can_write_impl() const override { return true; }
+		virtual bool has_error_impl() const override { return false; }
+
 	private:
 		Pipe(const Credentials&);
 

kernel/include/kernel/FS/ProcFS/Inode.h

@@ -43,7 +43,10 @@ namespace Kernel
 		// You may not write here and this is always non blocking
 		virtual BAN::ErrorOr<size_t> write_impl(off_t, BAN::ConstByteSpan) override		{ return BAN::Error::from_errno(EINVAL); }
 		virtual BAN::ErrorOr<void> truncate_impl(size_t) override						{ return BAN::Error::from_errno(EINVAL); }
-		virtual bool has_data_impl() const override										{ return true; }
+
+		virtual bool can_read_impl() const override { return true; }
+		virtual bool can_write_impl() const override { return false; }
+		virtual bool has_error_impl() const override { return false; }
 
 	private:
 		ProcROInode(Process&, size_t (Process::*)(off_t, BAN::ByteSpan) const, TmpFileSystem&, const TmpInodeInfo&);

kernel/include/kernel/FS/TmpFS/Inode.h

@@ -72,7 +72,10 @@ namespace Kernel
 		virtual BAN::ErrorOr<size_t> write_impl(off_t, BAN::ConstByteSpan) override;
 		virtual BAN::ErrorOr<void> truncate_impl(size_t) override;
 		virtual BAN::ErrorOr<void> chmod_impl(mode_t) override;
-		virtual bool has_data_impl() const override { return true; }
+
+		virtual bool can_read_impl() const override { return true; }
+		virtual bool can_write_impl() const override { return true; }
+		virtual bool has_error_impl() const override { return false; }
 
 	private:
 		TmpFileInode(TmpFileSystem&, ino_t, const TmpInodeInfo&);
@@ -91,7 +94,10 @@ namespace Kernel
 		virtual BAN::ErrorOr<size_t> write_impl(off_t, BAN::ConstByteSpan) override { return BAN::Error::from_errno(ENODEV); }
 		virtual BAN::ErrorOr<void> truncate_impl(size_t) override { return BAN::Error::from_errno(ENODEV); }
 		virtual BAN::ErrorOr<void> chmod_impl(mode_t) override;
-		virtual bool has_data_impl() const override { return true; }
+
+		virtual bool can_read_impl() const override { return false; }
+		virtual bool can_write_impl() const override { return false; }
+		virtual bool has_error_impl() const override { return false; }
 
 	private:
 		TmpSocketInode(TmpFileSystem&, ino_t, const TmpInodeInfo&);
@@ -110,6 +116,10 @@ namespace Kernel
 	protected:
 		virtual BAN::ErrorOr<BAN::String> link_target_impl() override;
 
+		virtual bool can_read_impl() const override { return false; }
+		virtual bool can_write_impl() const override { return false; }
+		virtual bool has_error_impl() const override { return false; }
+
 	private:
 		TmpSymlinkInode(TmpFileSystem&, ino_t, const TmpInodeInfo&);
 	};
@@ -136,6 +146,10 @@ namespace Kernel
 		virtual BAN::ErrorOr<void> create_directory_impl(BAN::StringView, mode_t, uid_t, gid_t) override final;
 		virtual BAN::ErrorOr<void> unlink_impl(BAN::StringView) override;
 
+		virtual bool can_read_impl() const override { return false; }
+		virtual bool can_write_impl() const override { return false; }
+		virtual bool has_error_impl() const override { return false; }
+
 	private:
 		template<TmpFuncs::for_each_valid_entry_callback F>
 		void for_each_valid_entry(F callback);

kernel/include/kernel/Input/PS2/Keyboard.h

@@ -48,7 +48,10 @@ namespace Kernel::Input
 
 	protected:
 		virtual BAN::ErrorOr<size_t> read_impl(off_t, BAN::ByteSpan) override;
-		virtual bool has_data_impl() const override;
+
+		virtual bool can_read_impl() const override { return !m_event_queue.empty(); }
+		virtual bool can_write_impl() const override { return false; }
+		virtual bool has_error_impl() const override { return false; }
 	};
 
 }

kernel/include/kernel/Input/PS2/Mouse.h

@@ -42,7 +42,10 @@ namespace Kernel::Input
 
 	protected:
 		virtual BAN::ErrorOr<size_t> read_impl(off_t, BAN::ByteSpan) override;
-		virtual bool has_data_impl() const override;
+
+		virtual bool can_read_impl() const override { return !m_event_queue.empty(); }
+		virtual bool can_write_impl() const override { return false; }
+		virtual bool has_error_impl() const override { return false; }
 	};
 
 }

kernel/include/kernel/LockGuard.h

@@ -2,6 +2,8 @@
 
 #include <BAN/NoCopyMove.h>
 
+#include <stdint.h>
+
 namespace Kernel
 {
 
@@ -27,4 +29,30 @@ namespace Kernel
 		Lock& m_lock;
 	};
 
+	template<typename Lock>
+	class LockFreeGuard
+	{
+		BAN_NON_COPYABLE(LockFreeGuard);
+		BAN_NON_MOVABLE(LockFreeGuard);
+
+	public:
+		LockFreeGuard(Lock& lock)
+			: m_lock(lock)
+			, m_depth(lock.lock_depth())
+		{
+			for (uint32_t i = 0; i < m_depth; i++)
+				m_lock.unlock();
+		}
+
+		~LockFreeGuard()
+		{
+			for (uint32_t i = 0; i < m_depth; i++)
+				m_lock.lock();
+		}
+
+	private:
+		Lock& m_lock;
+		const uint32_t m_depth;
+	};
+
 }

kernel/include/kernel/Networking/E1000/E1000.h

@@ -28,6 +28,8 @@ namespace Kernel
 		virtual bool link_up() override { return m_link_up; }
 		virtual int link_speed() override;
 
+		virtual size_t payload_mtu() const { return E1000_RX_BUFFER_SIZE - sizeof(EthernetHeader); }
+
 		virtual void handle_irq() final override;
 
 	protected:
@@ -44,6 +46,10 @@ namespace Kernel
 
 		virtual BAN::ErrorOr<void> send_bytes(BAN::MACAddress destination, EtherType protocol, BAN::ConstByteSpan) override;
 
+		virtual bool can_read_impl() const override { return false; }
+		virtual bool can_write_impl() const override { return false; }
+		virtual bool has_error_impl() const override { return false; }
+
 	private:
 		BAN::ErrorOr<void> read_mac_address();
 
@@ -67,7 +73,7 @@ namespace Kernel
 		BAN::UniqPtr<DMARegion>	m_tx_descriptor_region;
 
 		BAN::MACAddress	m_mac_address {};
-		bool		m_link_up { false };
+		bool			m_link_up { false };
 
 		friend class BAN::RefPtr<E1000>;
 	};

kernel/include/kernel/Networking/IPv4Layer.h

@@ -29,31 +29,10 @@ namespace Kernel
 		BAN::NetworkEndian<uint16_t> checksum		{ 0 };
 		BAN::IPv4Address src_address;
 		BAN::IPv4Address dst_address;
-
-		constexpr uint16_t calculate_checksum() const
-		{
-			uint32_t total_sum = 0;
-			for (size_t i = 0; i < sizeof(IPv4Header) / sizeof(uint16_t); i++)
-				total_sum += reinterpret_cast<const BAN::NetworkEndian<uint16_t>*>(this)[i];
-			total_sum -= checksum;
-			while (total_sum >> 16)
-				total_sum = (total_sum >> 16) + (total_sum & 0xFFFF);
-			return ~(uint16_t)total_sum;
-		}
-
-		constexpr bool is_valid_checksum() const
-		{
-			uint32_t total_sum = 0;
-			for (size_t i = 0; i < sizeof(IPv4Header) / sizeof(uint16_t); i++)
-				total_sum += reinterpret_cast<const BAN::NetworkEndian<uint16_t>*>(this)[i];
-			while (total_sum >> 16)
-				total_sum = (total_sum >> 16) + (total_sum & 0xFFFF);
-			return total_sum == 0xFFFF;
-		}
 	};
 	static_assert(sizeof(IPv4Header) == 20);
 
-	class IPv4Layer : public NetworkLayer
+	class IPv4Layer final : public NetworkLayer
 	{
 		BAN_NON_COPYABLE(IPv4Layer);
 		BAN_NON_MOVABLE(IPv4Layer);
@@ -66,10 +45,13 @@ namespace Kernel
 
 		void add_ipv4_packet(NetworkInterface&, BAN::ConstByteSpan);
 
-		virtual void unbind_socket(uint16_t port, BAN::RefPtr<NetworkSocket>) override;
-		virtual BAN::ErrorOr<void> bind_socket(uint16_t port, BAN::RefPtr<NetworkSocket>) override;
+		virtual void unbind_socket(BAN::RefPtr<NetworkSocket>, uint16_t port) override;
+		virtual BAN::ErrorOr<void> bind_socket_to_unused(BAN::RefPtr<NetworkSocket>, const sockaddr* send_address, socklen_t send_address_len) override;
+		virtual BAN::ErrorOr<void> bind_socket_to_address(BAN::RefPtr<NetworkSocket>, const sockaddr* address, socklen_t address_len) override;
 
-		virtual BAN::ErrorOr<size_t> sendto(NetworkSocket&, const sys_sendto_t*) override;
+		virtual BAN::ErrorOr<size_t> sendto(NetworkSocket&, BAN::ConstByteSpan, const sockaddr*, socklen_t) override;
+
+		virtual size_t header_size() const override { return sizeof(IPv4Header); }
 
 	private:
 		IPv4Layer();
@@ -86,7 +68,7 @@ namespace Kernel
 		};
 
 	private:
-		SpinLock				m_lock;
+		RecursiveSpinLock		m_lock;
 
 		BAN::UniqPtr<ARPTable>	m_arp_table;
 		Process*				m_process { nullptr };

kernel/include/kernel/Networking/NetworkInterface.h

@@ -52,6 +52,8 @@ namespace Kernel
 		virtual bool link_up() = 0;
 		virtual int link_speed() = 0;
 
+		virtual size_t payload_mtu() const = 0;
+
 		virtual dev_t rdev() const override { return m_rdev; }
 		virtual BAN::StringView name() const override { return m_name; }
 

kernel/include/kernel/Networking/NetworkLayer.h

@@ -5,6 +5,15 @@
 namespace Kernel
 {
 
+	struct PseudoHeader
+	{
+		BAN::IPv4Address src_ipv4				{ 0 };
+		BAN::IPv4Address dst_ipv4				{ 0 };
+		BAN::NetworkEndian<uint16_t> protocol	{ 0 };
+		BAN::NetworkEndian<uint16_t> extra		{ 0 };
+	};
+	static_assert(sizeof(PseudoHeader) == 12);
+
 	class NetworkSocket;
 	enum class SocketType;
 
@@ -13,13 +22,30 @@ namespace Kernel
 	public:
 		virtual ~NetworkLayer() {}
 
-		virtual void unbind_socket(uint16_t port, BAN::RefPtr<NetworkSocket>) = 0;
-		virtual BAN::ErrorOr<void> bind_socket(uint16_t port, BAN::RefPtr<NetworkSocket>) = 0;
+		virtual void unbind_socket(BAN::RefPtr<NetworkSocket>, uint16_t port) = 0;
+		virtual BAN::ErrorOr<void> bind_socket_to_unused(BAN::RefPtr<NetworkSocket>, const sockaddr* send_address, socklen_t send_address_len) = 0;
+		virtual BAN::ErrorOr<void> bind_socket_to_address(BAN::RefPtr<NetworkSocket>, const sockaddr* address, socklen_t address_len) = 0;
 
-		virtual BAN::ErrorOr<size_t> sendto(NetworkSocket&, const sys_sendto_t*) = 0;
+		virtual BAN::ErrorOr<size_t> sendto(NetworkSocket&, BAN::ConstByteSpan, const sockaddr*, socklen_t) = 0;
+
+		virtual size_t header_size() const = 0;
 
 	protected:
 		NetworkLayer() = default;
 	};
 
+	static uint16_t calculate_internet_checksum(BAN::ConstByteSpan packet, const PseudoHeader& pseudo_header)
+	{
+		uint32_t checksum = 0;
+		for (size_t i = 0; i < sizeof(pseudo_header) / sizeof(uint16_t); i++)
+			checksum += BAN::host_to_network_endian(reinterpret_cast<const uint16_t*>(&pseudo_header)[i]);
+		for (size_t i = 0; i < packet.size() / sizeof(uint16_t); i++)
+			checksum += BAN::host_to_network_endian(reinterpret_cast<const uint16_t*>(packet.data())[i]);
+		if (packet.size() % 2)
+			checksum += (uint16_t)packet[packet.size() - 1] << 8;
+		while (checksum >> 16)
+			checksum = (checksum >> 16) + (checksum & 0xFFFF);
+		return ~(uint16_t)checksum;
+	}
+
 }

kernel/include/kernel/Networking/NetworkSocket.h

@@ -6,14 +6,13 @@
 #include <kernel/Networking/NetworkInterface.h>
 #include <kernel/Networking/NetworkLayer.h>
 
-#include <netinet/in.h>
-
 namespace Kernel
 {
 
 	enum NetworkProtocol : uint8_t
 	{
 		ICMP = 0x01,
+		TCP = 0x06,
 		UDP = 0x11,
 	};
 
@@ -32,28 +31,22 @@ namespace Kernel
 		NetworkInterface& interface() { ASSERT(m_interface); return *m_interface; }
 
 		virtual size_t protocol_header_size() const = 0;
-		virtual void add_protocol_header(BAN::ByteSpan packet, uint16_t dst_port) = 0;
+		virtual void add_protocol_header(BAN::ByteSpan packet, uint16_t dst_port, PseudoHeader) = 0;
 		virtual NetworkProtocol protocol() const = 0;
 
-		virtual void add_packet(BAN::ConstByteSpan, BAN::IPv4Address sender_address, uint16_t sender_port) = 0;
+		virtual void receive_packet(BAN::ConstByteSpan, const sockaddr_storage& sender) = 0;
+
+		bool is_bound() const { return m_interface != nullptr; }
 
 	protected:
 		NetworkSocket(NetworkLayer&, ino_t, const TmpInodeInfo&);
 
-		virtual BAN::ErrorOr<size_t> read_packet(BAN::ByteSpan, sockaddr_in* sender_address) = 0;
-
-		virtual void on_close_impl() override;
-
-		virtual BAN::ErrorOr<void> bind_impl(const sockaddr* address, socklen_t address_len) override;
-		virtual BAN::ErrorOr<size_t> sendto_impl(const sys_sendto_t*) override;
-		virtual BAN::ErrorOr<size_t> recvfrom_impl(sys_recvfrom_t*) override;
-
 		virtual BAN::ErrorOr<long> ioctl_impl(int request, void* arg) override;
 
 	protected:
 		NetworkLayer&		m_network_layer;
 		NetworkInterface*	m_interface	= nullptr;
-		uint16_t			m_port		= PORT_NONE;
+		uint16_t			m_port { PORT_NONE };
 	};
 
 }

kernel/include/kernel/Networking/TCPSocket.h

@@ -0,0 +1,138 @@
+#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;
+
+		virtual bool can_read_impl() const override { return m_recv_window.data_size; }
+		virtual bool can_write_impl() const override { return m_state == State::Established; }
+		virtual bool has_error_impl() const override { return m_state != State::Established && m_state != State::Listen && m_state != State::SynSent && m_state != State::SynReceived; }
+
+	private:
+		enum class State
+		{
+			Closed = 0,
+			Listen,
+			SynSent,
+			SynReceived,
+			Established,
+			FinWait1,
+			FinWait2,
+			CloseWait,
+			Closing,
+			LastAck,
+			TimeWait,
+		};
+
+		struct RecvWindowInfo
+		{
+			uint32_t					start_seq	{ 0 }; // sequence number of first byte in buffer
+
+			bool						has_ghost_byte { false };
+
+			uint32_t					data_size	{ 0 }; // number of bytes in this buffer
+			BAN::UniqPtr<VirtualRange>	buffer;
+		};
+
+		struct SendWindowInfo
+		{
+			uint32_t					mss				{ 0 }; // maximum segment size
+			uint16_t					non_scaled_size	{ 0 }; // window size without scaling
+			uint8_t						scale			{ 0 }; // window scale
+			uint32_t 					scaled_size() const { return (uint32_t)non_scaled_size << scale; }
+
+			uint32_t					start_seq		{ 0 }; // sequence number of first byte in buffer
+			uint32_t					current_seq		{ 0 }; // sequence number of next send
+			uint32_t					current_ack		{ 0 }; // sequence number aknowledged by connection
+
+			uint64_t					last_send_ms	{ 0 }; // last send time, used for retransmission timeout
+
+			bool						has_ghost_byte { false };
+
+			uint32_t					data_size		{ 0 }; // number of bytes in this buffer
+			BAN::UniqPtr<VirtualRange>	buffer;
+		};
+
+	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 };
+
+		RecvWindowInfo m_recv_window;
+		SendWindowInfo m_send_window;
+
+		struct ConnectionInfo
+		{
+			sockaddr_storage	address;
+			socklen_t			address_len;
+		};
+		BAN::Optional<ConnectionInfo> m_connection_info;
+	};
+
+}

kernel/include/kernel/Networking/UDPSocket.h

@@ -24,30 +24,40 @@ namespace Kernel
 	public:
 		static BAN::ErrorOr<BAN::RefPtr<UDPSocket>> create(NetworkLayer&, ino_t, const TmpInodeInfo&);
 
-		virtual size_t protocol_header_size() const override { return sizeof(UDPHeader); }
-		virtual void add_protocol_header(BAN::ByteSpan packet, uint16_t dst_port) override;
 		virtual NetworkProtocol protocol() const override { return NetworkProtocol::UDP; }
 
+		virtual size_t protocol_header_size() const override { return sizeof(UDPHeader); }
+		virtual void add_protocol_header(BAN::ByteSpan packet, uint16_t dst_port, PseudoHeader) override;
+
 	protected:
-		virtual void add_packet(BAN::ConstByteSpan, BAN::IPv4Address sender_addr, uint16_t sender_port) override;
-		virtual BAN::ErrorOr<size_t> read_packet(BAN::ByteSpan, sockaddr_in* sender_address) override;
+		virtual void receive_packet(BAN::ConstByteSpan, const sockaddr_storage& sender) override;
+
+		virtual void on_close_impl() override;
+
+		virtual BAN::ErrorOr<void> bind_impl(const sockaddr* address, socklen_t address_len) 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 buffer, sockaddr* address, socklen_t* address_len) override;
+
+		virtual bool can_read_impl() const override { return !m_packets.empty(); }
+		virtual bool can_write_impl() const override { return true; }
+		virtual bool has_error_impl() const override { return false; }
 
 	private:
 		UDPSocket(NetworkLayer&, ino_t, const TmpInodeInfo&);
 
 		struct PacketInfo
 		{
-			BAN::IPv4Address	sender_addr;
-			uint16_t			sender_port;
+			sockaddr_storage	sender;
 			size_t				packet_size;
 		};
 
 	private:
 		static constexpr size_t				packet_buffer_size = 10 * PAGE_SIZE;
 		BAN::UniqPtr<VirtualRange>			m_packet_buffer;
-		BAN::CircularQueue<PacketInfo, 128>	m_packets;
+		BAN::CircularQueue<PacketInfo, 32>	m_packets;
 		size_t								m_packet_total_size { 0 };
-		Semaphore							m_semaphore;
+		SpinLock							m_packet_lock;
+		Semaphore							m_packet_semaphore;
 
 		friend class BAN::RefPtr<UDPSocket>;
 	};

kernel/include/kernel/Networking/UNIX/Socket.h

@@ -17,12 +17,18 @@ namespace Kernel
 		static BAN::ErrorOr<BAN::RefPtr<UnixDomainSocket>> create(SocketType, ino_t, const TmpInodeInfo&);
 
 	protected:
+		virtual void on_close_impl() override;
+
 		virtual BAN::ErrorOr<long> accept_impl(sockaddr*, socklen_t*) override;
 		virtual BAN::ErrorOr<void> connect_impl(const sockaddr*, socklen_t) override;
 		virtual BAN::ErrorOr<void> listen_impl(int) override;
 		virtual BAN::ErrorOr<void> bind_impl(const sockaddr*, socklen_t) override;
-		virtual BAN::ErrorOr<size_t> sendto_impl(const sys_sendto_t*) override;
-		virtual BAN::ErrorOr<size_t> recvfrom_impl(sys_recvfrom_t*) override;
+		virtual BAN::ErrorOr<size_t> sendto_impl(BAN::ConstByteSpan, const sockaddr*, socklen_t) override;
+		virtual BAN::ErrorOr<size_t> recvfrom_impl(BAN::ByteSpan, sockaddr*, socklen_t*) override;
+
+		virtual bool can_read_impl() const override;
+		virtual bool can_write_impl() const override;
+		virtual bool has_error_impl() const override { return false; }
 
 	private:
 		UnixDomainSocket(SocketType, ino_t, const TmpInodeInfo&);
@@ -47,7 +53,7 @@ namespace Kernel
 
 		struct ConnectionlessInfo
 		{
-
+			BAN::String peer_address;
 		};
 
 	private:

kernel/include/kernel/Process.h

@@ -16,6 +16,7 @@
 
 #include <sys/banan-os.h>
 #include <sys/mman.h>
+#include <sys/select.h>
 #include <sys/socket.h>
 #include <termios.h>
 
@@ -95,6 +96,8 @@ namespace Kernel
 		BAN::ErrorOr<long> sys_getegid() const { return m_credentials.egid(); }
 		BAN::ErrorOr<long> sys_getpgid(pid_t);
 
+		BAN::ErrorOr<long> sys_getpid() const { return pid(); }
+
 		BAN::ErrorOr<long> open_inode(BAN::RefPtr<Inode>, int flags);
 
 		BAN::ErrorOr<void> create_file_or_dir(BAN::StringView name, mode_t mode);
@@ -126,6 +129,8 @@ namespace Kernel
 
 		BAN::ErrorOr<long> sys_ioctl(int fildes, int request, void* arg);
 
+		BAN::ErrorOr<long> sys_pselect(sys_pselect_t* arguments);
+
 		BAN::ErrorOr<long> sys_pipe(int fildes[2]);
 		BAN::ErrorOr<long> sys_dup(int fildes);
 		BAN::ErrorOr<long> sys_dup2(int fildes, int fildes2);
@@ -145,7 +150,7 @@ namespace Kernel
 
 		BAN::ErrorOr<void> mount(BAN::StringView source, BAN::StringView target);
 
-		BAN::ErrorOr<long> sys_read_dir_entries(int fd, DirectoryEntryList* buffer, size_t buffer_size);
+		BAN::ErrorOr<long> sys_readdir(int fd, DirectoryEntryList* buffer, size_t buffer_size);
 
 		BAN::ErrorOr<long> sys_mmap(const sys_mmap_t*);
 		BAN::ErrorOr<long> sys_munmap(void* addr, size_t len);
@@ -154,7 +159,7 @@ namespace Kernel
 		BAN::ErrorOr<long> sys_tty_ctrl(int fildes, int command, int flags);
 
 		BAN::ErrorOr<long> sys_signal(int, void (*)(int));
-		static BAN::ErrorOr<long> sys_kill(pid_t pid, int signal);
+		BAN::ErrorOr<long> sys_kill(pid_t pid, int signal);
 
 		BAN::ErrorOr<long> sys_tcsetpgrp(int fd, pid_t pgid);
 

kernel/include/kernel/Random.h

@@ -0,0 +1,16 @@
+#pragma once
+
+#include <stdint.h>
+
+namespace Kernel
+{
+
+	class Random
+	{
+	public:
+		static void initialize();
+		static uint32_t get_u32();
+		static uint64_t get_u64();
+	};
+
+}

kernel/include/kernel/Scheduler.h

@@ -19,9 +19,9 @@ namespace Kernel
 		void reschedule();
 		void reschedule_if_idling();
 
-		void set_current_thread_sleeping(uint64_t);
+		void set_current_thread_sleeping(uint64_t wake_time);
 
-		void block_current_thread(Semaphore*);
+		void block_current_thread(Semaphore*, uint64_t wake_time);
 		void unblock_threads(Semaphore*);
 		// Makes sleeping or blocked thread with tid active.
 		void unblock_thread(pid_t tid);
@@ -36,6 +36,8 @@ namespace Kernel
 	private:
 		Scheduler() = default;
 
+		void set_current_thread_sleeping_impl(uint64_t wake_time);
+
 		void wake_threads();
 		[[nodiscard]] bool save_current_thread();
 		void remove_and_advance_current_thread();
@@ -50,18 +52,14 @@ namespace Kernel
 				: thread(thread)
 			{}
 
-			Thread* thread;
-			union
-			{
-				uint64_t	wake_time;
-				Semaphore*	semaphore;
-			};
+			Thread*		thread;
+			uint64_t	wake_time;
+			Semaphore*	semaphore;
 		};
 
 		Thread* m_idle_thread { nullptr };
 		BAN::LinkedList<SchedulerThread> m_active_threads;
 		BAN::LinkedList<SchedulerThread> m_sleeping_threads;
-		BAN::LinkedList<SchedulerThread> m_blocking_threads;
 
 		BAN::LinkedList<SchedulerThread>::iterator m_current_thread;
 

kernel/include/kernel/Semaphore.h

@@ -6,7 +6,9 @@ namespace Kernel
 	class Semaphore
 	{
 	public:
-		void block();
+		void block_indefinite();
+		void block_with_timeout(uint64_t timeout_ms);
+		void block_with_wake_time(uint64_t wake_time_ms);
 		void unblock();
 	};
 

kernel/include/kernel/SpinLock.h

@@ -19,6 +19,8 @@ namespace Kernel
 		void unlock();
 		bool is_locked() const;
 
+		uint32_t lock_depth() const { return m_locker != -1; }
+
 	private:
 		BAN::Atomic<pid_t> m_locker = -1;
 	};
@@ -34,6 +36,8 @@ namespace Kernel
 		void unlock();
 		bool is_locked() const;
 
+		uint32_t lock_depth() const { return m_lock_depth; }
+
 	private:
 		BAN::Atomic<pid_t>		m_locker		= -1;
 		BAN::Atomic<uint32_t>	m_lock_depth	= 0;

kernel/include/kernel/Storage/NVMe/Controller.h

@@ -24,6 +24,11 @@ namespace Kernel
 		virtual dev_t rdev() const override { return m_rdev; }
 		virtual BAN::StringView name() const override { return m_name; }
 
+	protected:
+		virtual bool can_read_impl() const override { return false; }
+		virtual bool can_write_impl() const override { return false; }
+		virtual bool has_error_impl() const override { return false; }
+
 	private:
 		NVMeController(PCI::Device& pci_device);
 		virtual BAN::ErrorOr<void> initialize() override;

kernel/include/kernel/Storage/Partition.h

@@ -46,6 +46,10 @@ namespace Kernel
 	protected:
 		virtual BAN::ErrorOr<size_t> read_impl(off_t, BAN::ByteSpan) override;
 
+		virtual bool can_read_impl() const override { return true; }
+		virtual bool can_write_impl() const override { return true; }
+		virtual bool has_error_impl() const override { return false; }
+
 	private:
 		const dev_t m_rdev;
 	};

kernel/include/kernel/Storage/StorageDevice.h

@@ -39,6 +39,10 @@ namespace Kernel
 		virtual BAN::ErrorOr<void> write_sectors_impl(uint64_t lba, uint64_t sector_count, BAN::ConstByteSpan) = 0;
 		void add_disk_cache();
 
+		virtual bool can_read_impl() const override { return true; }
+		virtual bool can_write_impl() const override { return true; }
+		virtual bool has_error_impl() const override { return false; }
+
 	private:
 		SpinLock							m_lock;
 		BAN::Optional<DiskCache>			m_disk_cache;

kernel/include/kernel/Terminal/TTY.h

@@ -44,7 +44,9 @@ namespace Kernel
 		virtual BAN::ErrorOr<void> chmod_impl(mode_t) override;
 		virtual BAN::ErrorOr<void> chown_impl(uid_t, gid_t) override;
 
-		virtual bool has_data_impl() const override;
+		virtual bool can_read_impl() const override { return m_output.flush; }
+		virtual bool can_write_impl() const override { return true; }
+		virtual bool has_error_impl() const override { return false; }
 
 	protected:
 		TTY(mode_t mode, uid_t uid, gid_t gid)

kernel/include/kernel/Thread.h

@@ -47,8 +47,10 @@ namespace Kernel
 		void handle_signal(int signal = 0);
 		bool add_signal(int signal);
 
-		// blocks semaphore and returns either on unblock, eintr or spuriously
-		BAN::ErrorOr<void> block_or_eintr(Semaphore&);
+		// blocks semaphore and returns either on unblock, eintr, spuriously or after timeout
+		BAN::ErrorOr<void> block_or_eintr_indefinite(Semaphore& semaphore);
+		BAN::ErrorOr<void> block_or_eintr_or_timeout(Semaphore& semaphore, uint64_t timeout_ms, bool etimedout);
+		BAN::ErrorOr<void> block_or_eintr_or_waketime(Semaphore& semaphore, uint64_t wake_time_ms, bool etimedout);
 
 		void set_return_rsp(uintptr_t& rsp) { m_return_rsp = &rsp; }
 		void set_return_rip(uintptr_t& rip) { m_return_rip = &rip; }

kernel/kernel/FS/DevFS/FileSystem.cpp

@@ -64,9 +64,8 @@ namespace Kernel
 				{
 					while (!s_instance->m_should_sync)
 					{
-						s_instance->m_device_lock.unlock();
-						s_instance->m_sync_semaphore.block();
-						s_instance->m_device_lock.lock();
+						LockFreeGuard _(s_instance->m_device_lock);
+						s_instance->m_sync_semaphore.block_indefinite();
 					}
 
 					for (auto& device : s_instance->m_devices)
@@ -105,7 +104,7 @@ namespace Kernel
 			m_sync_semaphore.unblock();
 		}
 		if (should_block)
-			m_sync_done.block();
+			m_sync_done.block_indefinite();
 	}
 
 	void DevFileSystem::add_device(BAN::RefPtr<Device> device)

kernel/kernel/FS/Inode.cpp

@@ -148,20 +148,20 @@ namespace Kernel
 		return listen_impl(backlog);
 	}
 
-	BAN::ErrorOr<size_t> Inode::sendto(const sys_sendto_t* arguments)
+	BAN::ErrorOr<size_t> Inode::sendto(BAN::ConstByteSpan message, const sockaddr* address, socklen_t address_len)
 	{
 		LockGuard _(m_lock);
 		if (!mode().ifsock())
 			return BAN::Error::from_errno(ENOTSOCK);
-		return sendto_impl(arguments);
+		return sendto_impl(message, address, address_len);
 	};
 
-	BAN::ErrorOr<size_t> Inode::recvfrom(sys_recvfrom_t* arguments)
+	BAN::ErrorOr<size_t> Inode::recvfrom(BAN::ByteSpan buffer, sockaddr* address, socklen_t* address_len)
 	{
 		LockGuard _(m_lock);
 		if (!mode().ifsock())
 			return BAN::Error::from_errno(ENOTSOCK);
-		return recvfrom_impl(arguments);
+		return recvfrom_impl(buffer, address, address_len);
 	};
 
 	BAN::ErrorOr<size_t> Inode::read(off_t offset, BAN::ByteSpan buffer)
@@ -201,10 +201,22 @@ namespace Kernel
 		return chown_impl(uid, gid);
 	}
 
-	bool Inode::has_data() const
+	bool Inode::can_read() const
 	{
 		LockGuard _(m_lock);
-		return has_data_impl();
+		return can_read_impl();
+	}
+
+	bool Inode::can_write() const
+	{
+		LockGuard _(m_lock);
+		return can_write_impl();
+	}
+
+	bool Inode::has_error() const
+	{
+		LockGuard _(m_lock);
+		return has_error_impl();
 	}
 
 	BAN::ErrorOr<long> Inode::ioctl(int request, void* arg)

kernel/kernel/FS/Pipe.cpp

@@ -1,5 +1,6 @@
 #include <kernel/FS/Pipe.h>
 #include <kernel/LockGuard.h>
+#include <kernel/Thread.h>
 #include <kernel/Timer/Timer.h>
 
 namespace Kernel
@@ -46,9 +47,8 @@ namespace Kernel
 		{
 			if (m_writing_count == 0)
 				return 0;
-			m_lock.unlock();
-			m_semaphore.block();
-			m_lock.lock();
+			LockFreeGuard lock_free(m_lock);
+			TRY(Thread::current().block_or_eintr_indefinite(m_semaphore));
 		}
 
 		size_t to_copy = BAN::Math::min<size_t>(buffer.size(), m_buffer.size());

kernel/kernel/Input/PS2/Keyboard.cpp

@@ -195,7 +195,7 @@ namespace Kernel::Input
 		while (true)
 		{
 			if (m_event_queue.empty())
-				TRY(Thread::current().block_or_eintr(m_semaphore));
+				TRY(Thread::current().block_or_eintr_indefinite(m_semaphore));
 
 			CriticalScope _;
 			if (m_event_queue.empty())
@@ -208,10 +208,4 @@ namespace Kernel::Input
 		}
 	}
 
-	bool PS2Keyboard::has_data_impl() const
-	{
-		CriticalScope _;
-		return !m_event_queue.empty();
-	}
-
 }

kernel/kernel/Input/PS2/Mouse.cpp

@@ -179,7 +179,7 @@ namespace Kernel::Input
 		while (true)
 		{
 			if (m_event_queue.empty())
-				TRY(Thread::current().block_or_eintr(m_semaphore));
+				TRY(Thread::current().block_or_eintr_indefinite(m_semaphore));
 
 			CriticalScope _;
 			if (m_event_queue.empty())
@@ -192,10 +192,4 @@ namespace Kernel::Input
 		}
 	}
 
-	bool PS2Mouse::has_data_impl() const
-	{
-		CriticalScope _;
-		return !m_event_queue.empty();
-	}
-
 }

kernel/kernel/Networking/ARPTable.cpp

@@ -155,7 +155,7 @@ namespace Kernel
 
 			if (!pending.has_value())
 			{
-				m_pending_semaphore.block();
+				m_pending_semaphore.block_indefinite();
 				continue;
 			}
 

kernel/kernel/Networking/IPv4Layer.cpp

@@ -3,7 +3,9 @@
 #include <kernel/Networking/ICMP.h>
 #include <kernel/Networking/IPv4Layer.h>
 #include <kernel/Networking/NetworkManager.h>
+#include <kernel/Networking/TCPSocket.h>
 #include <kernel/Networking/UDPSocket.h>
+#include <kernel/Random.h>
 
 #include <netinet/in.h>
 
@@ -12,6 +14,11 @@
 namespace Kernel
 {
 
+	enum IPv4Flags : uint16_t
+	{
+		DF = 1 << 14,
+	};
+
 	BAN::ErrorOr<BAN::UniqPtr<IPv4Layer>> IPv4Layer::create()
 	{
 		auto ipv4_manager = TRY(BAN::UniqPtr<IPv4Layer>::create());
@@ -57,10 +64,11 @@ namespace Kernel
 		header.protocol			= protocol;
 		header.src_address		= src_ipv4;
 		header.dst_address		= dst_ipv4;
-		header.checksum			= header.calculate_checksum();
+		header.checksum			= 0;
+		header.checksum			= calculate_internet_checksum(BAN::ConstByteSpan::from(header), {});
 	}
 
-	void IPv4Layer::unbind_socket(uint16_t port, BAN::RefPtr<NetworkSocket> socket)
+	void IPv4Layer::unbind_socket(BAN::RefPtr<NetworkSocket> socket, uint16_t port)
 	{
 		LockGuard _(m_lock);
 		if (m_bound_sockets.contains(port))
@@ -72,33 +80,55 @@ namespace Kernel
 		NetworkManager::get().TmpFileSystem::remove_from_cache(socket);
 	}
 
-	BAN::ErrorOr<void> IPv4Layer::bind_socket(uint16_t port, BAN::RefPtr<NetworkSocket> socket)
+	BAN::ErrorOr<void> IPv4Layer::bind_socket_to_unused(BAN::RefPtr<NetworkSocket> socket, const sockaddr* address, socklen_t address_len)
+	{
+		if (!address || address_len < (socklen_t)sizeof(sockaddr_in))
+			return BAN::Error::from_errno(EINVAL);
+		if (address->sa_family != AF_INET)
+			return BAN::Error::from_errno(EAFNOSUPPORT);
+		auto& sockaddr_in = *reinterpret_cast<const struct sockaddr_in*>(address);
+
+		LockGuard _(m_lock);
+
+		uint16_t port = NetworkSocket::PORT_NONE;
+		for (uint32_t i = 0; i < 100 && port == NetworkSocket::PORT_NONE; i++)
+			if (uint32_t temp = 0xC000 | (Random::get_u32() & 0x3FFF); !m_bound_sockets.contains(temp))
+				port = temp;
+		for (uint32_t temp = 0xC000; temp < 0xFFFF && port == NetworkSocket::PORT_NONE; temp++)
+			if (!m_bound_sockets.contains(temp))
+				port = temp;
+		if (port == NetworkSocket::PORT_NONE)
+		{
+			dwarnln("No ports available");
+			return BAN::Error::from_errno(EAGAIN);
+		}
+		dprintln_if(DEBUG_IPV4, "using port {}", port);
+
+		struct sockaddr_in target;
+		target.sin_family = AF_INET;
+		target.sin_port = BAN::host_to_network_endian(port);
+		target.sin_addr.s_addr = sockaddr_in.sin_addr.s_addr;
+		return bind_socket_to_address(socket, (sockaddr*)&target, sizeof(sockaddr_in));
+	}
+
+	BAN::ErrorOr<void> IPv4Layer::bind_socket_to_address(BAN::RefPtr<NetworkSocket> socket, const sockaddr* address, socklen_t address_len)
 	{
 		if (NetworkManager::get().interfaces().empty())
 			return BAN::Error::from_errno(EADDRNOTAVAIL);
 
-		LockGuard _(m_lock);
+		if (!address || address_len < (socklen_t)sizeof(sockaddr_in))
+			return BAN::Error::from_errno(EINVAL);
+		if (address->sa_family != AF_INET)
+			return BAN::Error::from_errno(EAFNOSUPPORT);
 
-		if (port == NetworkSocket::PORT_NONE)
-		{
-			for (uint32_t temp = 0xC000; temp < 0xFFFF; temp++)
-			{
-				if (!m_bound_sockets.contains(temp))
-				{
-					port = temp;
-					break;
-				}
-			}
-			if (port == NetworkSocket::PORT_NONE)
-			{
-				dwarnln("No ports available");
-				return BAN::Error::from_errno(EAGAIN);
-			}
-		}
+		auto& sockaddr_in = *reinterpret_cast<const struct sockaddr_in*>(address);
+		uint16_t port = BAN::host_to_network_endian(sockaddr_in.sin_port);
+
+		LockGuard _(m_lock);
 
 		if (m_bound_sockets.contains(port))
 			return BAN::Error::from_errno(EADDRINUSE);
-		TRY(m_bound_sockets.insert(port, socket));
+		TRY(m_bound_sockets.insert(port, TRY(socket->get_weak_ptr())));
 
 		// FIXME: actually determine proper interface
 		auto interface = NetworkManager::get().interfaces().front();
@@ -107,28 +137,37 @@ namespace Kernel
 		return {};
 	}
 
-	BAN::ErrorOr<size_t> IPv4Layer::sendto(NetworkSocket& socket, const sys_sendto_t* arguments)
+	BAN::ErrorOr<size_t> IPv4Layer::sendto(NetworkSocket& socket, BAN::ConstByteSpan buffer, const sockaddr* address, socklen_t address_len)
 	{
-		if (arguments->dest_addr->sa_family != AF_INET)
+		if (address->sa_family != AF_INET)
 			return BAN::Error::from_errno(EINVAL);
-		auto& sockaddr_in = *reinterpret_cast<const struct sockaddr_in*>(arguments->dest_addr);
+		if (address == nullptr || address_len != sizeof(sockaddr_in))
+			return BAN::Error::from_errno(EINVAL);
+		auto& sockaddr_in = *reinterpret_cast<const struct sockaddr_in*>(address);
 
 		auto dst_port = BAN::host_to_network_endian(sockaddr_in.sin_port);
 		auto dst_ipv4 = BAN::IPv4Address { sockaddr_in.sin_addr.s_addr };
 		auto dst_mac = TRY(m_arp_table->get_mac_from_ipv4(socket.interface(), dst_ipv4));
 
 		BAN::Vector<uint8_t> packet_buffer;
-		TRY(packet_buffer.resize(arguments->length + sizeof(IPv4Header) + socket.protocol_header_size()));
+		TRY(packet_buffer.resize(buffer.size() + sizeof(IPv4Header) + socket.protocol_header_size()));
 		auto packet = BAN::ByteSpan { packet_buffer.span() };
 
+		auto pseudo_header = PseudoHeader {
+			.src_ipv4 = socket.interface().get_ipv4_address(),
+			.dst_ipv4 = dst_ipv4,
+			.protocol = socket.protocol()
+		};
+
 		memcpy(
 			packet.slice(sizeof(IPv4Header)).slice(socket.protocol_header_size()).data(),
-			arguments->message,
-			arguments->length
+			buffer.data(),
+			buffer.size()
 		);
 		socket.add_protocol_header(
 			packet.slice(sizeof(IPv4Header)),
-			dst_port
+			dst_port,
+			pseudo_header
 		);
 		add_ipv4_header(
 			packet,
@@ -139,17 +178,7 @@ namespace Kernel
 
 		TRY(socket.interface().send_bytes(dst_mac, EtherType::IPv4, packet));
 
-		return arguments->length;
-	}
-
-	static uint16_t calculate_internet_checksum(BAN::ConstByteSpan packet)
-	{
-		uint32_t checksum = 0;
-		for (size_t i = 0; i < packet.size() / sizeof(uint16_t); i++)
-			checksum += BAN::host_to_network_endian(reinterpret_cast<const uint16_t*>(packet.data())[i]);
-		while (checksum >> 16)
-			checksum = (checksum >> 16) | (checksum & 0xFFFF);
-		return ~(uint16_t)checksum;
+		return buffer.size();
 	}
 
 	BAN::ErrorOr<void> IPv4Layer::handle_ipv4_packet(NetworkInterface& interface, BAN::ByteSpan packet)
@@ -157,9 +186,11 @@ namespace Kernel
 		auto& ipv4_header = packet.as<const IPv4Header>();
 		auto ipv4_data = packet.slice(sizeof(IPv4Header));
 
-		ASSERT(ipv4_header.is_valid_checksum());
-
 		auto src_ipv4 = ipv4_header.src_address;
+
+		uint16_t dst_port = NetworkSocket::PORT_NONE;
+		uint16_t src_port = NetworkSocket::PORT_NONE;
+
 		switch (ipv4_header.protocol)
 		{
 			case NetworkProtocol::ICMP:
@@ -174,7 +205,7 @@ namespace Kernel
 						auto& reply_icmp_header = ipv4_data.as<ICMPHeader>();
 						reply_icmp_header.type = ICMPType::EchoReply;
 						reply_icmp_header.checksum = 0;
-						reply_icmp_header.checksum = calculate_internet_checksum(ipv4_data);
+						reply_icmp_header.checksum = calculate_internet_checksum(ipv4_data, {});
 
 						add_ipv4_header(packet, interface.get_ipv4_address(), src_ipv4, NetworkProtocol::ICMP);
 
@@ -185,31 +216,60 @@ namespace Kernel
 						dprintln("Unhandleded ICMP packet (type {2H})", icmp_header.type);
 						break;
 				}
-				break;
+				return {};
 			}
 			case NetworkProtocol::UDP:
 			{
 				auto& udp_header = ipv4_data.as<const UDPHeader>();
-				uint16_t src_port = udp_header.src_port;
-				uint16_t dst_port = udp_header.dst_port;
-
-				LockGuard _(m_lock);
-
-				if (!m_bound_sockets.contains(dst_port) || !m_bound_sockets[dst_port].valid())
-				{
-					dprintln_if(DEBUG_IPV4, "no one is listening on port {}", dst_port);
-					return {};
-				}
-
-				auto udp_data = ipv4_data.slice(sizeof(UDPHeader));
-				m_bound_sockets[dst_port].lock()->add_packet(udp_data, src_ipv4, src_port);
+				dst_port = udp_header.dst_port;
+				src_port = udp_header.src_port;
+				break;
+			}
+			case NetworkProtocol::TCP:
+			{
+				auto& tcp_header = ipv4_data.as<const TCPHeader>();
+				dst_port = tcp_header.dst_port;
+				src_port = tcp_header.src_port;
 				break;
 			}
 			default:
 				dprintln_if(DEBUG_IPV4, "Unknown network protocol 0x{2H}", ipv4_header.protocol);
-				break;
+				return {};
 		}
 
+		ASSERT(dst_port != NetworkSocket::PORT_NONE);
+		ASSERT(src_port != NetworkSocket::PORT_NONE);
+
+		BAN::RefPtr<Kernel::NetworkSocket> bound_socket;
+
+		{
+			LockGuard _(m_lock);
+			if (!m_bound_sockets.contains(dst_port))
+			{
+				dprintln_if(DEBUG_IPV4, "no one is listening on port {}", dst_port);
+				return {};
+			}
+			bound_socket = m_bound_sockets[dst_port].lock();
+		}
+
+		if (!bound_socket)
+		{
+			dprintln_if(DEBUG_IPV4, "no one is listening on port {}", dst_port);
+			return {};
+		}
+
+		if (bound_socket->protocol() != ipv4_header.protocol)
+		{
+			dprintln_if(DEBUG_IPV4, "got data with wrong protocol ({}) on port {} (bound as {})", ipv4_header.protocol, dst_port, (uint8_t)bound_socket->protocol());
+			return {};
+		}
+
+		sockaddr_in sender;
+		sender.sin_family = AF_INET;
+		sender.sin_port = BAN::NetworkEndian<uint16_t>(src_port);
+		sender.sin_addr.s_addr = src_ipv4.raw;
+		bound_socket->receive_packet(ipv4_data, *reinterpret_cast<const sockaddr_storage*>(&sender));
+
 		return {};
 	}
 
@@ -230,7 +290,7 @@ namespace Kernel
 
 			if (!pending.has_value())
 			{
-				m_pending_semaphore.block();
+				m_pending_semaphore.block_indefinite();
 				continue;
 			}
 
@@ -262,14 +322,17 @@ namespace Kernel
 		}
 
 		auto& ipv4_header = buffer.as<const IPv4Header>();
-		if (!ipv4_header.is_valid_checksum())
+		if (calculate_internet_checksum(BAN::ConstByteSpan::from(ipv4_header), {}) != 0)
 		{
 			dwarnln("Invalid IPv4 packet");
 			return;
 		}
-		if (ipv4_header.total_length > buffer.size())
+		if (ipv4_header.total_length > buffer.size() || ipv4_header.total_length > interface.payload_mtu())
 		{
-			dwarnln("Too short IPv4 packet");
+			if (ipv4_header.flags_frament & IPv4Flags::DF)
+				dwarnln("Invalid IPv4 packet");
+			else
+				dwarnln("IPv4 fragmentation not supported");
 			return;
 		}
 

kernel/kernel/Networking/NetworkManager.cpp

@@ -5,6 +5,7 @@
 #include <kernel/Networking/E1000/E1000E.h>
 #include <kernel/Networking/ICMP.h>
 #include <kernel/Networking/NetworkManager.h>
+#include <kernel/Networking/TCPSocket.h>
 #include <kernel/Networking/UDPSocket.h>
 #include <kernel/Networking/UNIX/Socket.h>
 
@@ -76,15 +77,17 @@ namespace Kernel
 		switch (domain)
 		{
 			case SocketDomain::INET:
-			{
-				if (type != SocketType::DGRAM)
-					return BAN::Error::from_errno(EPROTOTYPE);
+				switch (type)
+				{
+					case SocketType::DGRAM:
+					case SocketType::STREAM:
+						break;
+					default:
+						return BAN::Error::from_errno(EPROTOTYPE);
+				}
 				break;
-			}
 			case SocketDomain::UNIX:
-			{
 				break;
-			}
 			default:
 				return BAN::Error::from_errno(EAFNOSUPPORT);
 		}
@@ -100,8 +103,17 @@ namespace Kernel
 		{
 			case SocketDomain::INET:
 			{
-				if (type == SocketType::DGRAM)
-					socket = TRY(UDPSocket::create(*m_ipv4_layer, ino, inode_info));
+				switch (type)
+				{
+					case SocketType::DGRAM:
+						socket = TRY(UDPSocket::create(*m_ipv4_layer, ino, inode_info));
+						break;
+					case SocketType::STREAM:
+						socket = TRY(TCPSocket::create(*m_ipv4_layer, ino, inode_info));
+						break;
+					default:
+						ASSERT_NOT_REACHED();
+				}
 				break;
 			}
 			case SocketDomain::UNIX:

kernel/kernel/Networking/NetworkSocket.cpp

@@ -15,12 +15,6 @@ namespace Kernel
 	{
 	}
 
-	void NetworkSocket::on_close_impl()
-	{
-		if (m_interface)
-			m_network_layer.unbind_socket(m_port, this);
-	}
-
 	void NetworkSocket::bind_interface_and_port(NetworkInterface* interface, uint16_t port)
 	{
 		ASSERT(!m_interface);
@@ -29,59 +23,6 @@ namespace Kernel
 		m_port = port;
 	}
 
-	BAN::ErrorOr<void> NetworkSocket::bind_impl(const sockaddr* address, socklen_t address_len)
-	{
-		if (m_interface || address_len != sizeof(sockaddr_in))
-			return BAN::Error::from_errno(EINVAL);
-		auto* addr_in = reinterpret_cast<const sockaddr_in*>(address);
-		uint16_t dst_port = BAN::host_to_network_endian(addr_in->sin_port);
-		return m_network_layer.bind_socket(dst_port, this);
-	}
-
-	BAN::ErrorOr<size_t> NetworkSocket::sendto_impl(const sys_sendto_t* arguments)
-	{
-		if (arguments->flags)
-		{
-			dprintln("flags not supported");
-			return BAN::Error::from_errno(ENOTSUP);
-		}
-
-		if (!m_interface)
-			TRY(m_network_layer.bind_socket(PORT_NONE, this));
-
-		return TRY(m_network_layer.sendto(*this, arguments));
-	}
-
-	BAN::ErrorOr<size_t> NetworkSocket::recvfrom_impl(sys_recvfrom_t* arguments)
-	{
-		sockaddr_in* sender_addr = nullptr;
-		if (arguments->address)
-		{
-			ASSERT(arguments->address_len);
-			if (*arguments->address_len < (socklen_t)sizeof(sockaddr_in))
-				*arguments->address_len = 0;
-			else
-			{
-				sender_addr = reinterpret_cast<sockaddr_in*>(arguments->address);
-				*arguments->address_len = sizeof(sockaddr_in);
-			}
-		}
-
-		if (!m_interface)
-		{
-			dprintln("No interface bound");
-			return BAN::Error::from_errno(EINVAL);
-		}
-
-		if (m_port == PORT_NONE)
-		{
-			dprintln("No port bound");
-			return BAN::Error::from_errno(EINVAL);
-		}
-
-		return TRY(read_packet(BAN::ByteSpan { reinterpret_cast<uint8_t*>(arguments->buffer), arguments->length }, sender_addr));
-	}
-
 	BAN::ErrorOr<long> NetworkSocket::ioctl_impl(int request, void* arg)
 	{
 		if (!arg)

kernel/kernel/Networking/TCPSocket.cpp

@@ -0,0 +1,644 @@
+#include <kernel/LockGuard.h>
+#include <kernel/Networking/TCPSocket.h>
+#include <kernel/Random.h>
+#include <kernel/Timer/Timer.h>
+
+#include <netinet/in.h>
+
+#define DEBUG_TCP 0
+
+namespace Kernel
+{
+
+	enum TCPOption : uint8_t
+	{
+		End					= 0x00,
+		NOP					= 0x01,
+		MaximumSeqmentSize	= 0x02,
+		WindowScale			= 0x03,
+	};
+
+	static constexpr size_t s_window_buffer_size = 15 * PAGE_SIZE;
+	static_assert(s_window_buffer_size <= UINT16_MAX);
+
+	BAN::ErrorOr<BAN::RefPtr<TCPSocket>> TCPSocket::create(NetworkLayer& network_layer, ino_t ino, const TmpInodeInfo& inode_info)
+	{
+		auto* socket_ptr = new TCPSocket(network_layer, ino, inode_info);
+		if (socket_ptr == nullptr)
+			return BAN::Error::from_errno(ENOMEM);
+		auto socket = BAN::RefPtr<TCPSocket>::adopt(socket_ptr);
+		socket->m_recv_window.buffer = TRY(VirtualRange::create_to_vaddr_range(
+			PageTable::kernel(),
+			KERNEL_OFFSET,
+			~(vaddr_t)0,
+			s_window_buffer_size,
+			PageTable::Flags::ReadWrite | PageTable::Flags::Present,
+			true
+		));
+		socket->m_send_window.buffer = TRY(VirtualRange::create_to_vaddr_range(
+			PageTable::kernel(),
+			KERNEL_OFFSET,
+			~(vaddr_t)0,
+			s_window_buffer_size,
+			PageTable::Flags::ReadWrite | PageTable::Flags::Present,
+			true
+		));
+		socket->m_process = Process::create_kernel(
+			[](void* socket_ptr)
+			{
+				reinterpret_cast<TCPSocket*>(socket_ptr)->process_task();
+			}, socket.ptr()
+		);
+		return socket;
+	}
+
+	TCPSocket::TCPSocket(NetworkLayer& network_layer, ino_t ino, const TmpInodeInfo& inode_info)
+		: NetworkSocket(network_layer, ino, inode_info)
+	{
+		m_send_window.start_seq = Random::get_u32() & 0x7FFFFFFF;
+		m_send_window.current_seq = m_send_window.start_seq;
+	}
+
+	TCPSocket::~TCPSocket()
+	{
+		ASSERT(!is_bound());
+		ASSERT(m_process == nullptr);
+		dprintln_if(DEBUG_TCP, "socket destroyed");
+	}
+
+	void TCPSocket::on_close_impl()
+	{
+		LockGuard _(m_lock);
+
+		if (!is_bound())
+			return;
+
+		switch (m_state)
+		{
+			case State::Established:
+				break;
+			case State::SynSent:
+				set_connection_as_closed();
+				// fall through
+			case State::SynReceived:
+			case State::FinWait1:
+			case State::FinWait2:
+			case State::CloseWait:
+			case State::Closing:
+			case State::TimeWait:
+			case State::LastAck:
+				return;
+			case State::Closed:		ASSERT_NOT_REACHED();
+			case State::Listen:		ASSERT_NOT_REACHED();
+		}
+
+		m_state = State::FinWait1;
+		m_should_ack = true;
+
+		dprintln_if(DEBUG_TCP, "Initiated close");
+	}
+
+	BAN::ErrorOr<void> TCPSocket::connect_impl(const sockaddr* address, socklen_t address_len)
+	{
+		if (address_len > (socklen_t)sizeof(sockaddr_storage))
+			address_len = sizeof(sockaddr_storage);
+
+		LockGuard _(m_lock);
+
+		ASSERT(!m_connection_info.has_value());
+
+		switch (m_state)
+		{
+			case State::Closed:
+				break;
+			case State::SynSent:
+			case State::SynReceived:
+				return BAN::Error::from_errno(EALREADY);
+			case State::Established:
+			case State::FinWait1:
+			case State::FinWait2:
+			case State::CloseWait:
+			case State::Closing:
+			case State::LastAck:
+			case State::TimeWait:
+				return BAN::Error::from_errno(EISCONN);
+			case State::Listen:
+				return BAN::Error::from_errno(EOPNOTSUPP);
+		};
+
+		if (!is_bound())
+			TRY(m_network_layer.bind_socket_to_unused(this, address, address_len));
+
+		m_connection_info.emplace(sockaddr_storage {}, address_len);
+		memcpy(&m_connection_info->address, address, address_len);
+
+		TRY(m_network_layer.sendto(*this, {}, address, address_len));
+		ASSERT(m_state == State::SynSent);
+		dprintln_if(DEBUG_TCP, "Sent SYN");
+
+		uint64_t wake_time_ms = SystemTimer::get().ms_since_boot() + 5000;
+		while (m_state != State::Established)
+		{
+			LockFreeGuard free(m_lock);
+			if (SystemTimer::get().ms_since_boot() >= wake_time_ms)
+				return BAN::Error::from_errno(ECONNREFUSED);
+			TRY(Thread::current().block_or_eintr_or_waketime(m_semaphore, wake_time_ms, true));
+		}
+
+		return {};
+	}
+
+	template<size_t Off, TCPOption Op>
+	static void add_tcp_header_option(TCPHeader& header, uint32_t value)
+	{
+		if constexpr(Op == TCPOption::MaximumSeqmentSize)
+		{
+			header.options[Off + 0] = Op;
+			header.options[Off + 1] = 0x04;
+			header.options[Off + 2] = value >> 8;
+			header.options[Off + 3] = value;
+		}
+		else if constexpr(Op == TCPOption::WindowScale)
+		{
+			header.options[Off + 0] = Op;
+			header.options[Off + 1] = 0x03;
+			header.options[Off + 2] = value;
+		}
+	}
+
+	struct ParsedTCPOptions
+	{
+		BAN::Optional<uint16_t> maximum_seqment_size;
+		BAN::Optional<uint8_t> window_scale;
+	};
+	static ParsedTCPOptions parse_tcp_options(const TCPHeader& header)
+	{
+		ParsedTCPOptions result;
+
+		for (size_t i = 0; i < header.data_offset * sizeof(uint32_t) - sizeof(TCPHeader) - 1; i++)
+		{
+			if (header.options[i] == TCPOption::End)
+				break;
+			if (header.options[i] == TCPOption::NOP)
+				continue;
+			if (header.options[i] == TCPOption::MaximumSeqmentSize)
+				result.maximum_seqment_size = BAN::host_to_network_endian(*reinterpret_cast<const uint16_t*>(&header.options[i + 2]));
+			if (header.options[i] == TCPOption::WindowScale)
+				result.window_scale = header.options[i + 2];
+			if (header.options[i + 1] == 0)
+				break;
+			i += header.options[i + 1] - 1;
+		}
+
+		return result;
+	}
+
+	void TCPSocket::add_protocol_header(BAN::ByteSpan packet, uint16_t dst_port, PseudoHeader pseudo_header)
+	{
+		auto& header = packet.as<TCPHeader>();
+		memset(&header, 0, sizeof(TCPHeader));
+		memset(header.options, TCPOption::End, m_tcp_options_bytes);
+
+		header.dst_port = dst_port;
+		header.src_port = m_port;
+		header.seq_number = m_send_window.current_seq + m_send_window.has_ghost_byte;
+		header.ack_number = m_recv_window.start_seq + m_recv_window.data_size + m_recv_window.has_ghost_byte;
+		header.data_offset = (sizeof(TCPHeader) + m_tcp_options_bytes) / sizeof(uint32_t);
+		header.window_size = m_recv_window.buffer->size();
+
+		ASSERT(m_recv_window.buffer->size() < 1 << (8 * sizeof(header.window_size)));
+
+		switch (m_state)
+		{
+			case State::Closed:
+			{
+				LockGuard _(m_lock);
+				header.syn = 1;
+				add_tcp_header_option<0, TCPOption::MaximumSeqmentSize>(header, m_interface->payload_mtu() - m_network_layer.header_size());
+				add_tcp_header_option<4, TCPOption::WindowScale>(header, 0);
+				m_state = State::SynSent;
+				m_send_window.start_seq++;
+				m_send_window.current_seq = m_send_window.start_seq;
+				break;
+			}
+			case State::SynSent:
+				header.ack = 1;
+				break;
+			case State::SynReceived:
+				header.ack = 1;
+				m_state = State::Established;
+				break;
+			case State::Established:
+				header.ack = 1;
+				break;
+			case State::CloseWait:
+			{
+				LockGuard _(m_lock);
+				header.ack = 1;
+				header.fin = 1;
+				m_state = State::LastAck;
+				dprintln_if(DEBUG_TCP, "Waiting for last ACK");
+				break;
+			}
+			case State::FinWait1:
+			{
+				LockGuard _(m_lock);
+				header.ack = 1;
+				header.fin = 1;
+				m_state = State::FinWait2;
+				break;
+			}
+			case State::FinWait2:
+			{
+				LockGuard _(m_lock);
+				header.ack = 1;
+				m_state = State::TimeWait;
+				m_time_wait_start_ms = SystemTimer::get().ms_since_boot();
+				dprintln_if(DEBUG_TCP, "Sent final ACK");
+				break;
+			}
+			case State::Listen:		ASSERT_NOT_REACHED();
+			case State::Closing:	ASSERT_NOT_REACHED();
+			case State::LastAck:	ASSERT_NOT_REACHED();
+			case State::TimeWait:	ASSERT_NOT_REACHED();
+		}
+
+		pseudo_header.extra = packet.size();
+		header.checksum = calculate_internet_checksum(packet, pseudo_header);
+	}
+
+	void TCPSocket::receive_packet(BAN::ConstByteSpan buffer, const sockaddr_storage& sender)
+	{
+		{
+			uint16_t checksum = 0;
+
+			if (sender.ss_family == AF_INET)
+			{
+				auto& sockaddr_in = *reinterpret_cast<const struct sockaddr_in*>(&sender);
+				checksum = calculate_internet_checksum(buffer,
+					PseudoHeader {
+						.src_ipv4 = BAN::IPv4Address(sockaddr_in.sin_addr.s_addr),
+						.dst_ipv4 = m_interface->get_ipv4_address(),
+						.protocol = NetworkProtocol::TCP,
+						.extra = buffer.size()
+					}
+				);
+			}
+			else
+			{
+				dwarnln("No tcp checksum validation for socket family {}", sender.ss_family);
+				return;
+			}
+
+			if (checksum != 0)
+			{
+				dprintln("Checksum does not match");
+				return;
+			}
+		}
+
+		auto& header = buffer.as<const TCPHeader>();
+
+		m_send_window.non_scaled_size = header.window_size;
+
+		auto payload = buffer.slice(header.data_offset * sizeof(uint32_t));
+
+		switch (m_state)
+		{
+			case State::Closed:
+				break;
+			case State::SynSent:
+			{
+				if (!header.ack || !header.syn)
+					break;
+
+				LockGuard _(m_lock);
+
+				if (header.ack_number != m_send_window.current_seq)
+				{
+					dprintln_if(DEBUG_TCP, "Invalid ack number in SYN/ACK", (uint32_t)header.ack_number, m_send_window.current_seq);
+					break;
+				}
+
+				auto options = parse_tcp_options(header);
+				if (options.maximum_seqment_size.has_value())
+					m_send_window.mss = *options.maximum_seqment_size;
+				if (options.window_scale.has_value())
+					m_send_window.scale = *options.window_scale;
+
+				m_send_window.start_seq = m_send_window.current_seq;
+				m_send_window.current_ack = m_send_window.current_seq;
+
+				m_recv_window.start_seq = header.seq_number + 1;
+
+				dprintln_if(DEBUG_TCP, "Got SYN/ACK");
+
+				m_should_ack = true;
+				m_state = State::SynReceived;
+				break;
+			}
+			case State::FinWait2:
+			case State::TimeWait:
+			case State::CloseWait:
+			case State::Established:
+			{
+				if (!header.ack)
+					break;
+
+				LockGuard _(m_lock);
+
+				if (header.fin)
+				{
+					if (m_recv_window.start_seq + m_recv_window.data_size != header.seq_number)
+						dprintln_if(DEBUG_TCP, "Got FIN, but missing packets");
+					else
+					{
+						if (m_state == State::FinWait2)
+							m_send_window.has_ghost_byte = true;
+						else
+							m_state = State::CloseWait;
+
+						m_recv_window.has_ghost_byte = true;
+						m_should_ack = true;
+						dprintln_if(DEBUG_TCP, "Got FIN");
+					}
+					break;
+				}
+
+				if (header.ack_number > m_send_window.current_ack)
+					m_send_window.current_ack = header.ack_number;
+
+				if (payload.size() > 0)
+				{
+					if (header.seq_number != m_recv_window.start_seq + m_recv_window.data_size)
+					{
+						dprintln_if(DEBUG_TCP, "Missing packet");
+						break;
+					}
+
+					if (m_recv_window.data_size + payload.size() > m_recv_window.buffer->size())
+					{
+						dprintln_if(DEBUG_TCP, "Cannot fit received bytes to window, waiting for retransmission");
+						break;
+					}
+
+					auto* buffer = reinterpret_cast<uint8_t*>(m_recv_window.buffer->vaddr());
+					memcpy(buffer + m_recv_window.data_size, payload.data(), payload.size());
+					m_recv_window.data_size += payload.size();
+
+					m_should_ack = true;
+
+					dprintln_if(DEBUG_TCP, "Received {} bytes", payload.size());
+				}
+
+				break;
+			}
+			case State::LastAck:
+				if (!header.ack)
+					break;
+				dprintln_if(DEBUG_TCP, "Got final ACK");
+				set_connection_as_closed();
+				break;
+			case State::Listen:			ASSERT_NOT_REACHED();
+			case State::SynReceived:	ASSERT_NOT_REACHED();
+			case State::FinWait1:		ASSERT_NOT_REACHED();
+			case State::Closing:		ASSERT_NOT_REACHED();
+		}
+
+		m_semaphore.unblock();
+	}
+
+	void TCPSocket::set_connection_as_closed()
+	{
+		if (is_bound())
+		{
+			m_network_layer.unbind_socket(this, m_port);
+			m_interface = nullptr;
+			m_port = PORT_NONE;
+			dprintln_if(DEBUG_TCP, "Socket unbound");
+		}
+
+		m_process = nullptr;
+	}
+
+	void TCPSocket::process_task()
+	{
+		// FIXME: this should be dynamic
+		static constexpr uint32_t retransmit_timeout_ms = 1000;
+
+		BAN::RefPtr<TCPSocket> keep_alive = this;
+
+		while (m_process)
+		{
+			uint64_t current_ms = SystemTimer::get().ms_since_boot();
+
+			if (m_state == State::TimeWait && current_ms >= m_time_wait_start_ms + 30'000)
+				set_connection_as_closed();
+
+			{
+				LockGuard _(m_lock);
+
+				if (m_should_ack)
+				{
+					m_should_ack = false;
+
+					ASSERT(m_connection_info.has_value());
+					auto* target_address = reinterpret_cast<const sockaddr*>(&m_connection_info->address);
+					auto target_address_len = m_connection_info->address_len;
+
+					if (auto ret = m_network_layer.sendto(*this, {}, target_address, target_address_len); ret.is_error())
+						dwarnln("{}", ret.error());
+
+					continue;
+				}
+
+				if (m_send_window.data_size > 0 && m_send_window.current_ack - m_send_window.has_ghost_byte > m_send_window.start_seq)
+				{
+					uint32_t acknowledged_bytes = m_send_window.current_ack - m_send_window.start_seq - m_send_window.has_ghost_byte;
+					ASSERT_LTE(acknowledged_bytes, m_send_window.data_size);
+
+					m_send_window.data_size -= acknowledged_bytes;
+					m_send_window.start_seq += acknowledged_bytes;
+
+					if (m_send_window.data_size > 0)
+					{
+						auto* send_buffer = reinterpret_cast<uint8_t*>(m_send_window.buffer->vaddr());
+						memmove(send_buffer, send_buffer + acknowledged_bytes, m_send_window.data_size);
+					}
+					else
+					{
+						m_send_window.last_send_ms = 0;
+					}
+
+					dprintln_if(DEBUG_TCP, "Target acknowledged {} bytes", acknowledged_bytes);
+
+					continue;
+				}
+
+				if (m_send_window.data_size > 0 && current_ms >= m_send_window.last_send_ms + retransmit_timeout_ms)
+				{
+					ASSERT(m_connection_info.has_value());
+					auto* target_address = reinterpret_cast<const sockaddr*>(&m_connection_info->address);
+					auto target_address_len = m_connection_info->address_len;
+
+					const uint32_t total_send = BAN::Math::min<uint32_t>(m_send_window.data_size, m_send_window.scaled_size());
+
+					m_send_window.current_seq = m_send_window.start_seq;
+
+					auto* send_buffer = reinterpret_cast<const uint8_t*>(m_send_window.buffer->vaddr());
+					for (uint32_t i = 0; i < total_send;)
+					{
+						const uint32_t to_send = BAN::Math::min(total_send - i, m_send_window.mss);
+
+						auto message = BAN::ConstByteSpan(send_buffer + i, to_send);
+
+						if (auto ret = m_network_layer.sendto(*this, message, target_address, target_address_len); ret.is_error())
+						{
+							dwarnln("{}", ret.error());
+							break;
+						}
+
+						dprintln_if(DEBUG_TCP, "Sent {} bytes", to_send);
+
+						m_send_window.current_seq += to_send;
+						i += to_send;
+					}
+
+					m_send_window.last_send_ms = current_ms;
+
+					continue;
+				}
+			}
+
+			m_semaphore.block_with_wake_time(current_ms + retransmit_timeout_ms);
+		}
+
+		m_semaphore.unblock();
+	}
+
+	BAN::ErrorOr<size_t> TCPSocket::recvfrom_impl(BAN::ByteSpan buffer, sockaddr*, socklen_t*)
+	{
+		LockGuard _(m_lock);
+
+		if (m_state == State::Closed)
+			return BAN::Error::from_errno(ENOTCONN);
+
+		while (m_recv_window.data_size == 0)
+		{
+			switch (m_state)
+			{
+				case State::SynSent:
+				case State::SynReceived:
+				case State::Established:
+				case State::CloseWait:
+				case State::Listen:
+					break;
+				case State::FinWait1:
+				case State::FinWait2:
+				case State::LastAck:
+				case State::TimeWait:
+					return BAN::Error::from_errno(ECONNRESET);
+				case State::Closed:		ASSERT_NOT_REACHED();
+				case State::Closing:	ASSERT_NOT_REACHED();
+			};
+
+			LockFreeGuard free(m_lock);
+			TRY(Thread::current().block_or_eintr_indefinite(m_semaphore));
+		}
+
+		uint32_t to_recv = BAN::Math::min<uint32_t>(buffer.size(), m_recv_window.data_size);
+
+		auto* recv_buffer = reinterpret_cast<uint8_t*>(m_recv_window.buffer->vaddr());
+		memcpy(buffer.data(), recv_buffer, to_recv);
+
+		m_recv_window.data_size -= to_recv;
+		m_recv_window.start_seq += to_recv;
+		if (m_recv_window.data_size > 0)
+			memmove(recv_buffer, recv_buffer + to_recv, m_recv_window.data_size);
+
+		return to_recv;
+	}
+
+	BAN::ErrorOr<size_t> TCPSocket::sendto_impl(BAN::ConstByteSpan message, const sockaddr* address, socklen_t address_len)
+	{
+		if (address)
+			return BAN::Error::from_errno(EISCONN);
+
+		if (message.size() > m_send_window.buffer->size())
+		{
+			for (size_t i = 0; i < message.size(); i++)
+			{
+				const size_t to_send = BAN::Math::min<size_t>(message.size() - i, m_send_window.buffer->size());
+				TRY(sendto_impl(message.slice(i, to_send), address, address_len));
+				i += to_send;
+			}
+			return message.size();
+		}
+
+		LockGuard _(m_lock);
+
+		if (m_state == State::Closed)
+			return BAN::Error::from_errno(ENOTCONN);
+
+		while (true)
+		{
+			switch (m_state)
+			{
+				case State::SynSent:
+				case State::SynReceived:
+				case State::Established:
+				case State::CloseWait:
+				case State::Listen:
+					break;
+				case State::FinWait1:
+				case State::FinWait2:
+				case State::LastAck:
+				case State::TimeWait:
+					return BAN::Error::from_errno(ECONNRESET);
+				case State::Closed:		ASSERT_NOT_REACHED();
+				case State::Closing:	ASSERT_NOT_REACHED();
+			};
+
+			if (m_send_window.data_size + message.size() <= m_send_window.buffer->size())
+				break;
+
+			LockFreeGuard free(m_lock);
+			TRY(Thread::current().block_or_eintr_indefinite(m_semaphore));
+		}
+
+		{
+			auto* buffer = reinterpret_cast<uint8_t*>(m_send_window.buffer->vaddr());
+			memcpy(buffer + m_send_window.data_size, message.data(), message.size());
+			m_send_window.data_size += message.size();
+		}
+
+		uint32_t target_ack = m_send_window.start_seq + m_send_window.data_size;
+		m_semaphore.unblock();
+
+		while (m_send_window.start_seq < target_ack)
+		{
+			switch (m_state)
+			{
+				case State::SynSent:
+				case State::SynReceived:
+				case State::Established:
+				case State::CloseWait:
+				case State::Listen:
+				case State::TimeWait:
+				case State::FinWait1:
+				case State::FinWait2:
+					break;
+				case State::LastAck:
+					return BAN::Error::from_errno(ECONNRESET);
+				case State::Closed:		ASSERT_NOT_REACHED();
+				case State::Closing:	ASSERT_NOT_REACHED();
+			};
+
+			LockFreeGuard free(m_lock);
+			TRY(Thread::current().block_or_eintr_indefinite(m_semaphore));
+		}
+
+		return message.size();
+	}
+
+}

kernel/kernel/Networking/UDPSocket.cpp

@@ -1,3 +1,4 @@
+#include <kernel/LockGuard.h>
 #include <kernel/Memory/Heap.h>
 #include <kernel/Networking/UDPSocket.h>
 #include <kernel/Thread.h>
@@ -23,7 +24,15 @@ namespace Kernel
 		: NetworkSocket(network_layer, ino, inode_info)
 	{ }
 
-	void UDPSocket::add_protocol_header(BAN::ByteSpan packet, uint16_t dst_port)
+	void UDPSocket::on_close_impl()
+	{
+		if (is_bound())
+			m_network_layer.unbind_socket(this, m_port);
+		m_port = PORT_NONE;
+		m_interface = nullptr;
+	}
+
+	void UDPSocket::add_protocol_header(BAN::ByteSpan packet, uint16_t dst_port, PseudoHeader)
 	{
 		auto& header = packet.as<UDPHeader>();
 		header.src_port = m_port;
@@ -32,9 +41,12 @@ namespace Kernel
 		header.checksum = 0;
 	}
 
-	void UDPSocket::add_packet(BAN::ConstByteSpan packet, BAN::IPv4Address sender_addr, uint16_t sender_port)
+	void UDPSocket::receive_packet(BAN::ConstByteSpan packet, const sockaddr_storage& sender)
 	{
-		CriticalScope _;
+		//auto& header = packet.as<const UDPHeader>();
+		auto payload = packet.slice(sizeof(UDPHeader));
+
+		LockGuard _(m_packet_lock);
 
 		if (m_packets.full())
 		{
@@ -42,60 +54,82 @@ namespace Kernel
 			return;
 		}
 
-		if (!m_packets.empty() && m_packet_total_size > m_packet_buffer->size())
+		if (m_packet_total_size + payload.size() > m_packet_buffer->size())
 		{
 			dprintln("Packet buffer full, dropping packet");
 			return;
 		}
 
 		void* buffer = reinterpret_cast<void*>(m_packet_buffer->vaddr() + m_packet_total_size);
-		memcpy(buffer, packet.data(), packet.size());
+		memcpy(buffer, payload.data(), payload.size());
 
-		m_packets.push(PacketInfo {
-			.sender_addr = sender_addr,
-			.sender_port = sender_port,
-			.packet_size = packet.size()
+		m_packets.emplace(PacketInfo {
+			.sender = sender,
+			.packet_size = payload.size()
 		});
-		m_packet_total_size += packet.size();
+		m_packet_total_size += payload.size();
 
-		m_semaphore.unblock();
+		m_packet_semaphore.unblock();
 	}
 
-	BAN::ErrorOr<size_t> UDPSocket::read_packet(BAN::ByteSpan buffer, sockaddr_in* sender_addr)
+	BAN::ErrorOr<void> UDPSocket::bind_impl(const sockaddr* address, socklen_t address_len)
 	{
-		while (m_packets.empty())
-			TRY(Thread::current().block_or_eintr(m_semaphore));
+		if (is_bound())
+			return BAN::Error::from_errno(EINVAL);
+		return m_network_layer.bind_socket_to_address(this, address, address_len);
+	}
 
-		CriticalScope _;
-		if (m_packets.empty())
-			return read_packet(buffer, sender_addr);
+	BAN::ErrorOr<size_t> UDPSocket::recvfrom_impl(BAN::ByteSpan buffer, sockaddr* address, socklen_t* address_len)
+	{
+		if (!is_bound())
+		{
+			dprintln("No interface bound");
+			return BAN::Error::from_errno(EINVAL);
+		}
+		ASSERT(m_port != PORT_NONE);
+
+		LockGuard _(m_packet_lock);
+
+		while (m_packets.empty())
+		{
+			LockFreeGuard free(m_packet_lock);
+			TRY(Thread::current().block_or_eintr_indefinite(m_packet_semaphore));
+		}
 
 		auto packet_info = m_packets.front();
 		m_packets.pop();
 
 		size_t nread = BAN::Math::min<size_t>(packet_info.packet_size, buffer.size());
 
+		uint8_t* packet_buffer = reinterpret_cast<uint8_t*>(m_packet_buffer->vaddr());
 		memcpy(
 			buffer.data(),
-			(const void*)m_packet_buffer->vaddr(),
+			packet_buffer,
 			nread
 		);
 		memmove(
-			(void*)m_packet_buffer->vaddr(),
-			(void*)(m_packet_buffer->vaddr() + packet_info.packet_size),
+			packet_buffer,
+			packet_buffer + packet_info.packet_size,
 			m_packet_total_size - packet_info.packet_size
 		);
 
 		m_packet_total_size -= packet_info.packet_size;
 
-		if (sender_addr)
+		if (address && address_len)
 		{
-			sender_addr->sin_family = AF_INET;
-			sender_addr->sin_port = BAN::NetworkEndian(packet_info.sender_port);
-			sender_addr->sin_addr.s_addr = packet_info.sender_addr.raw;
+			if (*address_len > (socklen_t)sizeof(sockaddr_storage))
+				*address_len = sizeof(sockaddr_storage);
+			memcpy(address, &packet_info.sender, *address_len);
 		}
 
 		return nread;
 	}
 
+	BAN::ErrorOr<size_t> UDPSocket::sendto_impl(BAN::ConstByteSpan message, const sockaddr* address, socklen_t address_len)
+	{
+		if (!is_bound())
+			TRY(m_network_layer.bind_socket_to_unused(this, address, address_len));
+		return TRY(m_network_layer.sendto(*this, message, address, address_len));
+	}
+
 }

kernel/kernel/Networking/UNIX/Socket.cpp

@@ -10,8 +10,8 @@
 namespace Kernel
 {
 
-	static BAN::HashMap<BAN::String, BAN::RefPtr<UnixDomainSocket>>	s_bound_sockets;
-	static SpinLock													s_bound_socket_lock;
+	static BAN::HashMap<BAN::String, BAN::WeakPtr<UnixDomainSocket>>	s_bound_sockets;
+	static SpinLock														s_bound_socket_lock;
 
 	static constexpr size_t s_packet_buffer_size = 10 * PAGE_SIZE;
 
@@ -47,6 +47,16 @@ namespace Kernel
 		}
 	}
 
+	void UnixDomainSocket::on_close_impl()
+	{
+		if (is_bound() && !is_bound_to_unused())
+		{
+			LockGuard _(s_bound_socket_lock);
+			if (s_bound_sockets.contains(m_bound_path))
+				s_bound_sockets.remove(m_bound_path);
+		}
+	}
+
 	BAN::ErrorOr<long> UnixDomainSocket::accept_impl(sockaddr* address, socklen_t* address_len)
 	{
 		if (!m_info.has<ConnectionInfo>())
@@ -56,7 +66,7 @@ namespace Kernel
 			return BAN::Error::from_errno(EINVAL);
 
 		while (connection_info.pending_connections.empty())
-			TRY(Thread::current().block_or_eintr(connection_info.pending_semaphore));
+			TRY(Thread::current().block_or_eintr_indefinite(connection_info.pending_semaphore));
 
 		BAN::RefPtr<UnixDomainSocket> pending;
 
@@ -74,7 +84,7 @@ namespace Kernel
 			return_inode = reinterpret_cast<UnixDomainSocket*>(return_inode_tmp.ptr());
 		}
 
-		TRY(return_inode->m_bound_path.append(m_bound_path));
+		TRY(return_inode->m_bound_path.push_back('X'));
 		return_inode->m_info.get<ConnectionInfo>().connection = TRY(pending->get_weak_ptr());
 		pending->m_info.get<ConnectionInfo>().connection = TRY(return_inode->get_weak_ptr());
 		pending->m_info.get<ConnectionInfo>().connection_done = true;
@@ -113,46 +123,48 @@ namespace Kernel
 			LockGuard _(s_bound_socket_lock);
 			if (!s_bound_sockets.contains(file.canonical_path))
 				return BAN::Error::from_errno(ECONNREFUSED);
-			target = s_bound_sockets[file.canonical_path];
+			target = s_bound_sockets[file.canonical_path].lock();
+			if (!target)
+				return BAN::Error::from_errno(ECONNREFUSED);
 		}
 
 		if (m_socket_type != target->m_socket_type)
 			return BAN::Error::from_errno(EPROTOTYPE);
 
-		if (m_info.has<ConnectionInfo>())
+		if (m_info.has<ConnectionlessInfo>())
 		{
-			auto& connection_info = m_info.get<ConnectionInfo>();
-			if (connection_info.connection)
-				return BAN::Error::from_errno(ECONNREFUSED);
-			if (connection_info.listening)
-				return BAN::Error::from_errno(EOPNOTSUPP);
-
-			connection_info.connection_done = false;
-
-			for (;;)
-			{
-				auto& target_info = target->m_info.get<ConnectionInfo>();
-				{
-					LockGuard _(target_info.pending_lock);
-					if (target_info.pending_connections.size() < target_info.pending_connections.capacity())
-					{
-						MUST(target_info.pending_connections.push(this));
-						target_info.pending_semaphore.unblock();
-						break;
-					}
-				}
-				TRY(Thread::current().block_or_eintr(target_info.pending_semaphore));
-			}
-
-			while (!connection_info.connection_done)
-				Scheduler::get().reschedule();
-
+			auto& connectionless_info = m_info.get<ConnectionlessInfo>();
+			connectionless_info.peer_address = BAN::move(file.canonical_path);
 			return {};
 		}
-		else
+
+		auto& connection_info = m_info.get<ConnectionInfo>();
+		if (connection_info.connection)
+			return BAN::Error::from_errno(ECONNREFUSED);
+		if (connection_info.listening)
+			return BAN::Error::from_errno(EOPNOTSUPP);
+
+		connection_info.connection_done = false;
+
+		for (;;)
 		{
-			return BAN::Error::from_errno(ENOTSUP);
+			auto& target_info = target->m_info.get<ConnectionInfo>();
+			{
+				LockGuard _(target_info.pending_lock);
+				if (target_info.pending_connections.size() < target_info.pending_connections.capacity())
+				{
+					MUST(target_info.pending_connections.push(this));
+					target_info.pending_semaphore.unblock();
+					break;
+				}
+			}
+			TRY(Thread::current().block_or_eintr_indefinite(target_info.pending_semaphore));
 		}
+
+		while (!connection_info.connection_done)
+			Scheduler::get().reschedule();
+
+		return {};
 	}
 
 	BAN::ErrorOr<void> UnixDomainSocket::listen_impl(int backlog)
@@ -195,7 +207,7 @@ namespace Kernel
 
 		LockGuard _(s_bound_socket_lock);
 		ASSERT(!s_bound_sockets.contains(file.canonical_path));
-		TRY(s_bound_sockets.emplace(file.canonical_path, this));
+		TRY(s_bound_sockets.emplace(file.canonical_path, TRY(get_weak_ptr())));
 		m_bound_path = BAN::move(file.canonical_path);
 
 		return {};
@@ -215,28 +227,6 @@ namespace Kernel
 		}
 	}
 
-	// This to feels too hacky to expose out of here
-	struct LockFreeGuard
-	{
-		LockFreeGuard(RecursivePrioritySpinLock& lock)
-			: m_lock(lock)
-			, m_depth(lock.lock_depth())
-		{
-			for (uint32_t i = 0; i < m_depth; i++)
-				m_lock.unlock();
-		}
-
-		~LockFreeGuard()
-		{
-			for (uint32_t i = 0; i < m_depth; i++)
-				m_lock.lock();
-		}
-
-	private:
-		RecursivePrioritySpinLock& m_lock;
-		const uint32_t m_depth;
-	};
-
 	BAN::ErrorOr<void> UnixDomainSocket::add_packet(BAN::ConstByteSpan packet)
 	{
 		LockGuard _(m_lock);
@@ -244,7 +234,7 @@ namespace Kernel
 		while (m_packet_sizes.full() || m_packet_size_total + packet.size() > s_packet_buffer_size)
 		{
 			LockFreeGuard _(m_lock);
-			TRY(Thread::current().block_or_eintr(m_packet_semaphore));
+			TRY(Thread::current().block_or_eintr_indefinite(m_packet_semaphore));
 		}
 
 		uint8_t* packet_buffer = reinterpret_cast<uint8_t*>(m_packet_buffer->vaddr() + m_packet_size_total);
@@ -258,35 +248,87 @@ namespace Kernel
 		return {};
 	}
 
-	BAN::ErrorOr<size_t> UnixDomainSocket::sendto_impl(const sys_sendto_t* arguments)
+	bool UnixDomainSocket::can_read_impl() const
 	{
-		if (arguments->flags)
-			return BAN::Error::from_errno(ENOTSUP);
-		if (arguments->length > s_packet_buffer_size)
+		if (m_info.has<ConnectionInfo>())
+		{
+			auto& connection_info = m_info.get<ConnectionInfo>();
+			if (!connection_info.connection)
+				return false;
+		}
+
+		return m_packet_size_total > 0;
+	}
+
+	bool UnixDomainSocket::can_write_impl() const
+	{
+		if (m_info.has<ConnectionInfo>())
+		{
+			auto& connection_info = m_info.get<ConnectionInfo>();
+			return connection_info.connection.valid();
+		}
+
+		return true;
+	}
+
+	BAN::ErrorOr<size_t> UnixDomainSocket::sendto_impl(BAN::ConstByteSpan message, const sockaddr* address, socklen_t address_len)
+	{
+		if (message.size() > s_packet_buffer_size)
 			return BAN::Error::from_errno(ENOBUFS);
 
 		if (m_info.has<ConnectionInfo>())
 		{
 			auto& connection_info = m_info.get<ConnectionInfo>();
-			if (arguments->dest_addr)
+			if (address)
 				return BAN::Error::from_errno(EISCONN);
 			auto target = connection_info.connection.lock();
 			if (!target)
 				return BAN::Error::from_errno(ENOTCONN);
-			TRY(target->add_packet({ reinterpret_cast<const uint8_t*>(arguments->message), arguments->length }));
-			return arguments->length;
+			TRY(target->add_packet(message));
+			return message.size();
 		}
 		else
 		{
-			return BAN::Error::from_errno(ENOTSUP);
+			BAN::String canonical_path;
+
+			if (!address)
+			{
+				auto& connectionless_info = m_info.get<ConnectionlessInfo>();
+				if (connectionless_info.peer_address.empty())
+					return BAN::Error::from_errno(EDESTADDRREQ);
+				TRY(canonical_path.append(connectionless_info.peer_address));
+			}
+			else
+			{
+				if (address_len != sizeof(sockaddr_un))
+					return BAN::Error::from_errno(EINVAL);
+				auto& sockaddr_un = *reinterpret_cast<const struct sockaddr_un*>(address);
+				if (sockaddr_un.sun_family != AF_UNIX)
+					return BAN::Error::from_errno(EAFNOSUPPORT);
+
+				auto absolute_path = TRY(Process::current().absolute_path_of(sockaddr_un.sun_path));
+				auto file = TRY(VirtualFileSystem::get().file_from_absolute_path(
+					Process::current().credentials(),
+					absolute_path,
+					O_WRONLY
+				));
+
+				canonical_path = BAN::move(file.canonical_path);
+			}
+
+			LockGuard _(s_bound_socket_lock);
+			if (!s_bound_sockets.contains(canonical_path))
+				return BAN::Error::from_errno(EDESTADDRREQ);
+			auto target = s_bound_sockets[canonical_path].lock();
+			if (!target)
+				return BAN::Error::from_errno(EDESTADDRREQ);
+			TRY(target->add_packet(message));
+			return message.size();
 		}
 	}
 
-	BAN::ErrorOr<size_t> UnixDomainSocket::recvfrom_impl(sys_recvfrom_t* arguments)
+	BAN::ErrorOr<size_t> UnixDomainSocket::recvfrom_impl(BAN::ByteSpan buffer, sockaddr*, socklen_t*)
 	{
-		if (arguments->flags)
-			return BAN::Error::from_errno(ENOTSUP);
-
 		if (m_info.has<ConnectionInfo>())
 		{
 			auto& connection_info = m_info.get<ConnectionInfo>();
@@ -297,21 +339,21 @@ namespace Kernel
 		while (m_packet_size_total == 0)
 		{
 			LockFreeGuard _(m_lock);
-			TRY(Thread::current().block_or_eintr(m_packet_semaphore));
+			TRY(Thread::current().block_or_eintr_indefinite(m_packet_semaphore));
 		}
 
 		uint8_t* packet_buffer = reinterpret_cast<uint8_t*>(m_packet_buffer->vaddr());
 
 		size_t nread = 0;
 		if (is_streaming())
-			nread = BAN::Math::min(arguments->length, m_packet_size_total);
+			nread = BAN::Math::min(buffer.size(), m_packet_size_total);
 		else
 		{
-			nread = BAN::Math::min(arguments->length, m_packet_sizes.front());
+			nread = BAN::Math::min(buffer.size(), m_packet_sizes.front());
 			m_packet_sizes.pop();
 		}
 
-		memcpy(arguments->buffer, packet_buffer, nread);
+		memcpy(buffer.data(), packet_buffer, nread);
 		memmove(packet_buffer, packet_buffer + nread, m_packet_size_total - nread);
 		m_packet_size_total -= nread;
 

kernel/kernel/OpenFileDescriptorSet.cpp

@@ -331,7 +331,7 @@ namespace Kernel
 	{
 		TRY(validate_fd(fd));
 		auto& open_file = m_open_files[fd];
-		if ((open_file->flags & O_NONBLOCK) && !open_file->inode->has_data())
+		if ((open_file->flags & O_NONBLOCK) && !open_file->inode->can_read())
 			return 0;
 		size_t nread = TRY(open_file->inode->read(open_file->offset, buffer));
 		open_file->offset += nread;
@@ -342,6 +342,8 @@ namespace Kernel
 	{
 		TRY(validate_fd(fd));
 		auto& open_file = m_open_files[fd];
+		if ((open_file->flags & O_NONBLOCK) && !open_file->inode->can_write())
+			return 0;
 		if (open_file->flags & O_APPEND)
 			open_file->offset = open_file->inode->size();
 		size_t nwrite = TRY(open_file->inode->write(open_file->offset, buffer));

kernel/kernel/Process.cpp

@@ -568,7 +568,7 @@ namespace Kernel
 			return BAN::Error::from_errno(ECHILD);
 
 		while (!target->m_exit_status.exited)
-			TRY(Thread::current().block_or_eintr(target->m_exit_status.semaphore));
+			TRY(Thread::current().block_or_eintr_indefinite(target->m_exit_status.semaphore));
 
 		int exit_status = target->m_exit_status.exit_code;
 		target->m_exit_status.waiting--;
@@ -983,7 +983,8 @@ namespace Kernel
 		if (!inode->mode().ifsock())
 			return BAN::Error::from_errno(ENOTSOCK);
 
-		return TRY(inode->sendto(arguments));
+		BAN::ConstByteSpan message { reinterpret_cast<const uint8_t*>(arguments->message), arguments->length };
+		return TRY(inode->sendto(message, arguments->dest_addr, arguments->dest_len));
 	}
 
 	BAN::ErrorOr<long> Process::sys_recvfrom(sys_recvfrom_t* arguments)
@@ -1006,7 +1007,8 @@ namespace Kernel
 		if (!inode->mode().ifsock())
 			return BAN::Error::from_errno(ENOTSOCK);
 
-		return TRY(inode->recvfrom(arguments));
+		BAN::ByteSpan buffer { reinterpret_cast<uint8_t*>(arguments->buffer), arguments->length };
+		return TRY(inode->recvfrom(buffer, arguments->address, arguments->address_len));
 	}
 
 	BAN::ErrorOr<long> Process::sys_ioctl(int fildes, int request, void* arg)
@@ -1016,6 +1018,86 @@ namespace Kernel
 		return TRY(inode->ioctl(request, arg));
 	}
 
+	BAN::ErrorOr<long> Process::sys_pselect(sys_pselect_t* arguments)
+	{
+		LockGuard _(m_lock);
+
+		TRY(validate_pointer_access(arguments, sizeof(sys_pselect_t)));
+		if (arguments->readfds)
+			TRY(validate_pointer_access(arguments->readfds, sizeof(fd_set)));
+		if (arguments->writefds)
+			TRY(validate_pointer_access(arguments->writefds, sizeof(fd_set)));
+		if (arguments->errorfds)
+			TRY(validate_pointer_access(arguments->errorfds, sizeof(fd_set)));
+		if (arguments->timeout)
+			TRY(validate_pointer_access(arguments->timeout, sizeof(timespec)));
+		if (arguments->sigmask)
+			TRY(validate_pointer_access(arguments->sigmask, sizeof(sigset_t)));
+
+		if (arguments->sigmask)
+			return BAN::Error::from_errno(ENOTSUP);
+
+		uint64_t timedout_ms = SystemTimer::get().ms_since_boot();
+		if (arguments->timeout)
+		{
+			timedout_ms += arguments->timeout->tv_sec * 1000;
+			timedout_ms += arguments->timeout->tv_nsec / 1'000'000;
+		}
+
+		fd_set readfds;		FD_ZERO(&readfds);
+		fd_set writefds;	FD_ZERO(&writefds);
+		fd_set errorfds;	FD_ZERO(&errorfds);
+
+		long set_bits = 0;
+		while (set_bits == 0)
+		{
+			if (arguments->timeout && SystemTimer::get().ms_since_boot() >= timedout_ms)
+				break;
+
+			auto update_fds =
+				[&](int fd, fd_set* source, fd_set* dest, bool (Inode::*func)() const)
+				{
+					if (source == nullptr)
+						return;
+
+					if (!FD_ISSET(fd, source))
+						return;
+
+					auto inode_or_error = m_open_file_descriptors.inode_of(fd);
+					if (inode_or_error.is_error())
+						return;
+
+					auto inode = inode_or_error.release_value();
+					auto mode = inode->mode();
+					if (!mode.ifreg() && !mode.ififo() && !mode.ifsock() && !inode->is_pipe() && !inode->is_tty())
+						return;
+
+					if ((inode_or_error.value().ptr()->*func)())
+					{
+						FD_SET(fd, dest);
+						set_bits++;
+					}
+				};
+
+			for (int i = 0; i < arguments->nfds; i++)
+			{
+				update_fds(i, arguments->readfds, &readfds, &Inode::can_read);
+				update_fds(i, arguments->writefds, &writefds, &Inode::can_write);
+				update_fds(i, arguments->errorfds, &errorfds, &Inode::can_read);
+			}
+
+			SystemTimer::get().sleep(1);
+		}
+
+		if (arguments->readfds)
+			memcpy(arguments->readfds, &readfds, sizeof(fd_set));
+		if (arguments->writefds)
+			memcpy(arguments->writefds, &writefds, sizeof(fd_set));
+		if (arguments->errorfds)
+			memcpy(arguments->errorfds, &errorfds, sizeof(fd_set));
+		return set_bits;
+	}
+
 	BAN::ErrorOr<long> Process::sys_pipe(int fildes[2])
 	{
 		LockGuard _(m_lock);
@@ -1136,7 +1218,7 @@ namespace Kernel
 		return BAN::Error::from_errno(EUNKNOWN);
 	}
 
-	BAN::ErrorOr<long> Process::sys_read_dir_entries(int fd, DirectoryEntryList* list, size_t list_size)
+	BAN::ErrorOr<long> Process::sys_readdir(int fd, DirectoryEntryList* list, size_t list_size)
 	{
 		LockGuard _(m_lock);
 		TRY(validate_pointer_access(list, list_size));

kernel/kernel/Random.cpp

@@ -0,0 +1,44 @@
+#include <kernel/Debug.h>
+#include <kernel/CPUID.h>
+#include <kernel/Random.h>
+
+namespace Kernel
+{
+
+
+	// Constants and algorithm from https://en.wikipedia.org/wiki/Permuted_congruential_generator
+
+	static uint64_t s_rand_seed = 0x4d595df4d0f33173;
+	static constexpr uint64_t s_rand_multiplier = 6364136223846793005;
+	static constexpr uint64_t s_rand_increment = 1442695040888963407;
+
+	void Random::initialize()
+	{
+		uint32_t ecx, edx;
+		CPUID::get_features(ecx, edx);
+
+		if (ecx & CPUID::ECX_RDRND)
+			asm volatile("rdrand %0" : "=a"(s_rand_seed));
+		else
+			dprintln("No RDRAND available");
+	}
+
+	uint32_t Random::get_u32()
+	{
+		auto rotr32 = [](uint32_t x, unsigned r) { return x >> r | x << (-r & 31); };
+
+		uint64_t x = s_rand_seed;
+		unsigned count = (unsigned)(x >> 59);
+
+		s_rand_seed = x * s_rand_multiplier + s_rand_increment;
+		x ^= x >> 18;
+
+		return rotr32(x >> 27, count) % UINT32_MAX;
+	}
+
+	uint64_t Random::get_u64()
+	{
+		return ((uint64_t)get_u32() << 32) | get_u32();
+	}
+
+}

kernel/kernel/Scheduler.cpp

@@ -278,12 +278,9 @@ namespace Kernel
 		ASSERT_NOT_REACHED();
 	}
 
-	void Scheduler::set_current_thread_sleeping(uint64_t wake_time)
+	void Scheduler::set_current_thread_sleeping_impl(uint64_t wake_time)
 	{
-		VERIFY_STI();
-		DISABLE_INTERRUPTS();
-
-		ASSERT(m_current_thread);
+		VERIFY_CLI();
 
 		if (save_current_thread())
 		{
@@ -310,42 +307,37 @@ namespace Kernel
 		ASSERT_NOT_REACHED();
 	}
 
-	void Scheduler::block_current_thread(Semaphore* semaphore)
+	void Scheduler::set_current_thread_sleeping(uint64_t wake_time)
 	{
 		VERIFY_STI();
 		DISABLE_INTERRUPTS();
 
 		ASSERT(m_current_thread);
 
-		if (save_current_thread())
-		{
-			ENABLE_INTERRUPTS();
-			return;
-		}
+		m_current_thread->semaphore = nullptr;
+		set_current_thread_sleeping_impl(wake_time);
+	}
+
+	void Scheduler::block_current_thread(Semaphore* semaphore, uint64_t wake_time)
+	{
+		VERIFY_STI();
+		DISABLE_INTERRUPTS();
+
+		ASSERT(m_current_thread);
 
 		m_current_thread->semaphore = semaphore;
-		m_active_threads.move_element_to_other_linked_list(
-			m_blocking_threads,
-			m_blocking_threads.end(),
-			m_current_thread
-		);
-
-		m_current_thread = {};
-		advance_current_thread();
-
-		execute_current_thread();
-		ASSERT_NOT_REACHED();
+		set_current_thread_sleeping_impl(wake_time);
 	}
 
 	void Scheduler::unblock_threads(Semaphore* semaphore)
 	{
 		CriticalScope critical;
 
-		for (auto it = m_blocking_threads.begin(); it != m_blocking_threads.end();)
+		for (auto it = m_sleeping_threads.begin(); it != m_sleeping_threads.end();)
 		{
 			if (it->semaphore == semaphore)
 			{
-				it = m_blocking_threads.move_element_to_other_linked_list(
+				it = m_sleeping_threads.move_element_to_other_linked_list(
 					m_active_threads,
 					m_active_threads.end(),
 					it
@@ -362,19 +354,6 @@ namespace Kernel
 	{
 		CriticalScope _;
 
-		for (auto it = m_blocking_threads.begin(); it != m_blocking_threads.end(); it++)
-		{
-			if (it->thread->tid() == tid)
-			{
-				m_blocking_threads.move_element_to_other_linked_list(
-					m_active_threads,
-					m_active_threads.end(),
-					it
-				);
-				return;
-			}
-		}
-
 		for (auto it = m_sleeping_threads.begin(); it != m_sleeping_threads.end(); it++)
 		{
 			if (it->thread->tid() == tid)

kernel/kernel/Semaphore.cpp

@@ -1,12 +1,23 @@
 #include <kernel/Scheduler.h>
 #include <kernel/Semaphore.h>
+#include <kernel/Timer/Timer.h>
 
 namespace Kernel
 {
 
-	void Semaphore::block()
+	void Semaphore::block_indefinite()
 	{
-		Scheduler::get().block_current_thread(this);
+		Scheduler::get().block_current_thread(this, ~(uint64_t)0);
+	}
+
+	void Semaphore::block_with_timeout(uint64_t timeout_ms)
+	{
+		Scheduler::get().block_current_thread(this, SystemTimer::get().ms_since_boot() + timeout_ms);
+	}
+
+	void Semaphore::block_with_wake_time(uint64_t wake_time)
+	{
+		Scheduler::get().block_current_thread(this, wake_time);
 	}
 
 	void Semaphore::unblock()

kernel/kernel/SpinLock.cpp

@@ -7,6 +7,7 @@ namespace Kernel
 	void SpinLock::lock()
 	{
 		pid_t tid = Scheduler::current_tid();
+		ASSERT(tid != m_locker);
 		while (!m_locker.compare_exchange(-1, tid))
 			Scheduler::get().reschedule();
 	}

kernel/kernel/Storage/NVMe/Queue.cpp

@@ -67,13 +67,12 @@ namespace Kernel
 
 		while (SystemTimer::get().ms_since_boot() < start_time + s_nvme_command_timeout_ms)
 		{
-			if (!m_done)
+			if (m_done)
 			{
-				m_semaphore.block();
-				continue;
+				m_done = false;
+				return m_status;
 			}
-			m_done = false;
-			return m_status;
+			m_semaphore.block_with_wake_time(start_time + s_nvme_command_timeout_ms);
 		}
 
 		return 0xFFFF;

kernel/kernel/Syscall.cpp

@@ -1,3 +1,4 @@
+#include <BAN/Bitcast.h>
 #include <kernel/Debug.h>
 #include <kernel/InterruptStack.h>
 #include <kernel/Process.h>
@@ -19,6 +20,14 @@ namespace Kernel
 
 	extern "C" long sys_fork_trampoline();
 
+	using SyscallHandler = BAN::ErrorOr<long> (Process::*)(uintptr_t, uintptr_t, uintptr_t, uintptr_t, uintptr_t);
+
+	static const SyscallHandler s_syscall_handlers[] = {
+#define O(enum, name) BAN::bit_cast<SyscallHandler>(&Process::sys_ ## name),
+		__SYSCALL_LIST(O)
+#undef O
+	};
+
 	extern "C" long cpp_syscall_handler(int syscall, uintptr_t arg1, uintptr_t arg2, uintptr_t arg3, uintptr_t arg4, uintptr_t arg5, InterruptStack& interrupt_stack)
 	{
 		ASSERT((interrupt_stack.cs & 0b11) == 0b11);
@@ -28,219 +37,14 @@ namespace Kernel
 
 		asm volatile("sti");
 
-		(void)arg1;
-		(void)arg2;
-		(void)arg3;
-		(void)arg4;
-		(void)arg5;
-		(void)interrupt_stack;
-
 		BAN::ErrorOr<long> ret = BAN::Error::from_errno(ENOSYS);
 
-		switch (syscall)
-		{
-		case SYS_EXIT:
-			ret = Process::current().sys_exit((int)arg1);
-			break;
-		case SYS_READ:
-			ret = Process::current().sys_read((int)arg1, (void*)arg2, (size_t)arg3);
-			break;
-		case SYS_WRITE:
-			ret = Process::current().sys_write((int)arg1, (const void*)arg2, (size_t)arg3);
-			break;
-		case SYS_TERMID:
-			ret = Process::current().sys_termid((char*)arg1);
-			break;
-		case SYS_CLOSE:
-			ret = Process::current().sys_close((int)arg1);
-			break;
-		case SYS_OPEN:
-			ret = Process::current().sys_open((const char*)arg1, (int)arg2, (mode_t)arg3);
-			break;
-		case SYS_OPENAT:
-			ret = Process::current().sys_openat((int)arg1, (const char*)arg2, (int)arg3, (mode_t)arg4);
-			break;
-		case SYS_SEEK:
-			ret = Process::current().sys_seek((int)arg1, (long)arg2, (int)arg3);
-			break;
-		case SYS_TELL:
-			ret = Process::current().sys_tell((int)arg1);
-			break;
-		case SYS_GET_TERMIOS:
-			ret = Process::current().sys_gettermios((::termios*)arg1);
-			break;
-		case SYS_SET_TERMIOS:
-			ret = Process::current().sys_settermios((const ::termios*)arg1);
-			break;
-		case SYS_FORK:
+		if (syscall < 0 || syscall >= __SYSCALL_COUNT)
+			dwarnln("No syscall {}", syscall);
+		else if (syscall == SYS_FORK)
 			ret = sys_fork_trampoline();
-			break;
-		case SYS_EXEC:
-			ret = Process::current().sys_exec((const char*)arg1, (const char* const*)arg2, (const char* const*)arg3);
-			break;
-		case SYS_SLEEP:
-			ret = Process::current().sys_sleep((unsigned int)arg1);
-			break;
-		case SYS_WAIT:
-			ret = Process::current().sys_wait((pid_t)arg1, (int*)arg2, (int)arg3);
-			break;
-		case SYS_FSTAT:
-			ret = Process::current().sys_fstat((int)arg1, (struct stat*)arg2);
-			break;
-		case SYS_READ_DIR_ENTRIES:
-			ret = Process::current().sys_read_dir_entries((int)arg1, (API::DirectoryEntryList*)arg2, (size_t)arg3);
-			break;
-		case SYS_SET_UID:
-			ret = Process::current().sys_setuid((uid_t)arg1);
-			break;
-		case SYS_SET_GID:
-			ret = Process::current().sys_setgid((gid_t)arg1);
-			break;
-		case SYS_SET_EUID:
-			ret = Process::current().sys_seteuid((uid_t)arg1);
-			break;
-		case SYS_SET_EGID:
-			ret = Process::current().sys_setegid((gid_t)arg1);
-			break;
-		case SYS_SET_REUID:
-			ret = Process::current().sys_setreuid((uid_t)arg1, (uid_t)arg2);
-			break;
-		case SYS_SET_REGID:
-			ret = Process::current().sys_setregid((gid_t)arg1, (gid_t)arg2);
-			break;
-		case SYS_GET_UID:
-			ret = Process::current().sys_getuid();
-			break;
-		case SYS_GET_GID:
-			ret = Process::current().sys_getgid();
-			break;
-		case SYS_GET_EUID:
-			ret = Process::current().sys_geteuid();
-			break;
-		case SYS_GET_EGID:
-			ret = Process::current().sys_getegid();
-			break;
-		case SYS_GET_PWD:
-			ret = Process::current().sys_getpwd((char*)arg1, (size_t)arg2);
-			break;
-		case SYS_SET_PWD:
-			ret = Process::current().sys_setpwd((const char*)arg1);
-			break;
-		case SYS_CLOCK_GETTIME:
-			ret = Process::current().sys_clock_gettime((clockid_t)arg1, (timespec*)arg2);
-			break;
-		case SYS_PIPE:
-			ret = Process::current().sys_pipe((int*)arg1);
-			break;
-		case SYS_DUP:
-			ret = Process::current().sys_dup((int)arg1);
-			break;
-		case SYS_DUP2:
-			ret = Process::current().sys_dup2((int)arg1, (int)arg2);
-			break;
-		case SYS_KILL:
-			ret = Process::current().sys_kill((pid_t)arg1, (int)arg2);
-			break;
-		case SYS_SIGNAL:
-			ret = Process::current().sys_signal((int)arg1, (void (*)(int))arg2);
-			break;
-		case SYS_TCSETPGRP:
-			ret = Process::current().sys_tcsetpgrp((int)arg1, (pid_t)arg2);
-			break;
-		case SYS_GET_PID:
-			ret = Process::current().pid();
-			break;
-		case SYS_GET_PGID:
-			ret = Process::current().sys_getpgid((pid_t)arg1);
-			break;
-		case SYS_SET_PGID:
-			ret = Process::current().sys_setpgid((pid_t)arg1, (pid_t)arg2);
-			break;
-		case SYS_FCNTL:
-			ret = Process::current().sys_fcntl((int)arg1, (int)arg2, (int)arg3);
-			break;
-		case SYS_NANOSLEEP:
-			ret = Process::current().sys_nanosleep((const timespec*)arg1, (timespec*)arg2);
-			break;
-		case SYS_FSTATAT:
-			ret = Process::current().sys_fstatat((int)arg1, (const char*)arg2, (struct stat*)arg3, (int)arg4);
-			break;
-		case SYS_STAT:
-			ret = Process::current().sys_stat((const char*)arg1, (struct stat*)arg2, (int)arg3);
-			break;
-		case SYS_SYNC:
-			ret = Process::current().sys_sync((bool)arg1);
-			break;
-		case SYS_MMAP:
-			ret = Process::current().sys_mmap((const sys_mmap_t*)arg1);
-			break;
-		case SYS_MUNMAP:
-			ret = Process::current().sys_munmap((void*)arg1, (size_t)arg2);
-			break;
-		case SYS_TTY_CTRL:
-			ret = Process::current().sys_tty_ctrl((int)arg1, (int)arg2, (int)arg3);
-			break;
-		case SYS_POWEROFF:
-			ret = Process::current().sys_poweroff((int)arg1);
-			break;
-		case SYS_CHMOD:
-			ret = Process::current().sys_chmod((const char*)arg1, (mode_t)arg2);
-			break;
-		case SYS_CREATE:
-			ret = Process::current().sys_create((const char*)arg1, (mode_t)arg2);
-			break;
-		case SYS_CREATE_DIR:
-			ret = Process::current().sys_create_dir((const char*)arg1, (mode_t)arg2);
-			break;
-		case SYS_UNLINK:
-			ret = Process::current().sys_unlink((const char*)arg1);
-			break;
-		case SYS_READLINK:
-			ret = Process::current().sys_readlink((const char*)arg1, (char*)arg2, (size_t)arg3);
-			break;
-		case SYS_READLINKAT:
-			ret = Process::current().sys_readlinkat((int)arg1, (const char*)arg2, (char*)arg3, (size_t)arg4);
-			break;
-		case SYS_MSYNC:
-			ret = Process::current().sys_msync((void*)arg1, (size_t)arg2, (int)arg3);
-			break;
-		case SYS_PREAD:
-			ret = Process::current().sys_pread((int)arg1, (void*)arg2, (size_t)arg3, (off_t)arg4);
-			break;
-		case SYS_CHOWN:
-			ret = Process::current().sys_chown((const char*)arg1, (uid_t)arg2, (gid_t)arg3);
-			break;
-		case SYS_LOAD_KEYMAP:
-			ret = Process::current().sys_load_keymap((const char*)arg1);
-			break;
-		case SYS_SOCKET:
-			ret = Process::current().sys_socket((int)arg1, (int)arg2, (int)arg3);
-			break;
-		case SYS_BIND:
-			ret = Process::current().sys_bind((int)arg1, (const sockaddr*)arg2, (socklen_t)arg3);
-			break;
-		case SYS_SENDTO:
-			ret = Process::current().sys_sendto((const sys_sendto_t*)arg1);
-			break;
-		case SYS_RECVFROM:
-			ret = Process::current().sys_recvfrom((sys_recvfrom_t*)arg1);
-			break;
-		case SYS_IOCTL:
-			ret = Process::current().sys_ioctl((int)arg1, (int)arg2, (void*)arg3);
-			break;
-		case SYS_ACCEPT:
-			ret = Process::current().sys_accept((int)arg1, (sockaddr*)arg2, (socklen_t*)arg3);
-			break;
-		case SYS_CONNECT:
-			ret = Process::current().sys_connect((int)arg1, (const sockaddr*)arg2, (socklen_t)arg3);
-			break;
-		case SYS_LISTEN:
-			ret = Process::current().sys_listen((int)arg1, (int)arg2);
-			break;
-		default:
-			dwarnln("Unknown syscall {}", syscall);
-			break;
-		}
+		else
+			ret = (Process::current().*s_syscall_handlers[syscall])(arg1, arg2, arg3, arg4, arg5);
 
 		asm volatile("cli");
 

kernel/kernel/Terminal/TTY.cpp

@@ -92,7 +92,7 @@ namespace Kernel
 				while (true)
 				{
 					while (!TTY::current()->m_tty_ctrl.receive_input)
-						TTY::current()->m_tty_ctrl.semaphore.block();
+						TTY::current()->m_tty_ctrl.semaphore.block_indefinite();
 
 					Input::KeyEvent event;
 					size_t read = MUST(inode->read(0, BAN::ByteSpan::from(event)));
@@ -210,7 +210,7 @@ namespace Kernel
 		// ^C
 		if (ch == '\x03')
 		{
-			if (auto ret = Process::sys_kill(-m_foreground_pgrp, SIGINT); ret.is_error())
+			if (auto ret = Process::current().sys_kill(-m_foreground_pgrp, SIGINT); ret.is_error())
 				dwarnln("TTY: {}", ret.error());
 			return;
 		}
@@ -323,7 +323,7 @@ namespace Kernel
 			uint32_t depth = m_lock.lock_depth();
 			for (uint32_t i = 0; i < depth; i++)
 				m_lock.unlock();
-			auto eintr = Thread::current().block_or_eintr(m_output.semaphore);
+			auto eintr = Thread::current().block_or_eintr_indefinite(m_output.semaphore);
 			for (uint32_t i = 0; i < depth; i++)
 				m_lock.lock();
 			if (eintr.is_error())
@@ -358,12 +358,6 @@ namespace Kernel
 		return buffer.size();
 	}
 
-	bool TTY::has_data_impl() const
-	{
-		LockGuard _(m_lock);
-		return m_output.flush;
-	}
-
 	void TTY::putchar_current(uint8_t ch)
 	{
 		ASSERT(s_tty);

kernel/kernel/Thread.cpp

@@ -8,6 +8,7 @@
 #include <kernel/Process.h>
 #include <kernel/Scheduler.h>
 #include <kernel/Thread.h>
+#include <kernel/Timer/Timer.h>
 
 namespace Kernel
 {
@@ -30,7 +31,6 @@ namespace Kernel
 	void Thread::terminate()
 	{
 		CriticalScope _;
-		ASSERT(this == &Thread::current());
 		m_state = Thread::State::Terminated;
 		if (this == &Thread::current())
 			Scheduler::get().execute_current_thread();
@@ -343,16 +343,34 @@ namespace Kernel
 		return false;
 	}
 
-	BAN::ErrorOr<void> Thread::block_or_eintr(Semaphore& semaphore)
+	BAN::ErrorOr<void> Thread::block_or_eintr_indefinite(Semaphore& semaphore)
 	{
 		if (is_interrupted_by_signal())
 			return BAN::Error::from_errno(EINTR);
-		semaphore.block();
+		semaphore.block_indefinite();
 		if (is_interrupted_by_signal())
 			return BAN::Error::from_errno(EINTR);
 		return {};
 	}
 
+	BAN::ErrorOr<void> Thread::block_or_eintr_or_timeout(Semaphore& semaphore, uint64_t timeout_ms, bool etimedout)
+	{
+		uint64_t wake_time_ms = SystemTimer::get().ms_since_boot() + timeout_ms;
+		return block_or_eintr_or_waketime(semaphore, wake_time_ms, etimedout);
+	}
+
+	BAN::ErrorOr<void> Thread::block_or_eintr_or_waketime(Semaphore& semaphore, uint64_t wake_time_ms, bool etimedout)
+	{
+		if (is_interrupted_by_signal())
+			return BAN::Error::from_errno(EINTR);
+		semaphore.block_with_wake_time(wake_time_ms);
+		if (is_interrupted_by_signal())
+			return BAN::Error::from_errno(EINTR);
+		if (etimedout && SystemTimer::get().ms_since_boot() >= wake_time_ms)
+			return BAN::Error::from_errno(ETIMEDOUT);
+		return {};
+	}
+
 	void Thread::validate_stack() const
 	{
 		if (stack_base() <= m_rsp && m_rsp <= stack_base() + stack_size())

kernel/kernel/kernel.cpp

@@ -19,6 +19,7 @@
 #include <kernel/PCI.h>
 #include <kernel/PIC.h>
 #include <kernel/Process.h>
+#include <kernel/Random.h>
 #include <kernel/Scheduler.h>
 #include <kernel/Syscall.h>
 #include <kernel/Terminal/Serial.h>
@@ -153,6 +154,9 @@ extern "C" void kernel_main(uint32_t boot_magic, uint32_t boot_info)
 		dprintln("Virtual TTY initialized");
 	}
 
+	Random::initialize();
+	dprintln("RNG initialized");
+
 	MUST(Scheduler::initialize());
 	dprintln("Scheduler initialized");
 

libc/CMakeLists.txt

@@ -21,6 +21,7 @@ set(LIBC_SOURCES
 	stropts.cpp
 	sys/banan-os.cpp
 	sys/mman.cpp
+	sys/select.cpp
 	sys/socket.cpp
 	sys/stat.cpp
 	sys/wait.cpp

libc/arpa/inet.cpp

@@ -50,3 +50,26 @@ char* inet_ntoa(struct in_addr in)
 	);
 	return buffer;
 }
+
+const char* inet_ntop(int af, const void* __restrict src, char* __restrict dst, socklen_t size)
+{
+	if (af == AF_INET)
+	{
+		if (size < INET_ADDRSTRLEN)
+		{
+			errno = ENOSPC;
+			return nullptr;
+		}
+		uint32_t he = ntohl(reinterpret_cast<const in_addr*>(src)->s_addr);
+		sprintf(dst, "%u.%u.%u.%u",
+			(he >> 24) & 0xFF,
+			(he >> 16) & 0xFF,
+			(he >>  8) & 0xFF,
+			(he >>  0) & 0xFF
+		);
+		return dst;
+	}
+
+	errno = EAFNOSUPPORT;
+	return nullptr;
+}

libc/dirent.cpp

@@ -79,7 +79,7 @@ struct dirent* readdir(DIR* dirp)
 		return &dirp->current->dirent;
 	}
 
-	if (syscall(SYS_READ_DIR_ENTRIES, dirp->fd, dirp->buffer, dirp->buffer_size) == -1)
+	if (syscall(SYS_READ_DIR, dirp->fd, dirp->buffer, dirp->buffer_size) == -1)
 		return nullptr;
 
 	if (dirp->buffer->entry_count == 0)

libc/include/bits/types/timeval.h

@@ -0,0 +1,20 @@
+#ifndef _BITS_TIMEVAL_H
+#define _BITS_TIMEVAL_H 1
+
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+#define __need_time_t
+#define __need_suseconds_t
+#include <sys/types.h>
+
+struct timeval
+{
+	time_t		tv_sec;		/* Seconds. */
+	suseconds_t	tc_usec;	/* Microseconds. */
+};
+
+__END_DECLS
+
+#endif

libc/include/sys/select.h

@@ -7,9 +7,7 @@
 
 __BEGIN_DECLS
 
-#define __need_time_t
-#define __need_suseconds_t
-#include <sys/types.h>
+#include <bits/types/timeval.h>
 
 #include <signal.h>
 #include <time.h>
@@ -50,6 +48,16 @@ typedef struct {
 			(setp)->__bits[i] = (__fd_mask)0; \
 	} while (0)
 
+struct sys_pselect_t
+{
+	int nfds;
+	fd_set* readfds;
+	fd_set* writefds;
+	fd_set* errorfds;
+	const struct timespec* timeout;
+	const sigset_t* sigmask;
+};
+
 int pselect(int nfds, fd_set* __restrict readfds, fd_set* __restrict writefds, fd_set* __restrict errorfds, const struct timespec* __restrict timeout, const sigset_t* __restrict sigmask);
 int select(int nfds, fd_set* __restrict readfds, fd_set* __restrict writefds, fd_set* __restrict errorfds, struct timeval* __restrict timeout);
 

libc/include/sys/syscall.h

@@ -5,72 +5,82 @@
 
 __BEGIN_DECLS
 
-#define SYS_EXIT 1
-#define SYS_READ 2
-#define SYS_WRITE 3
-#define SYS_TERMID 4
-#define SYS_CLOSE 5
-#define SYS_OPEN 6
-#define SYS_OPENAT 7
-#define SYS_SEEK 11
-#define SYS_TELL 12
-#define SYS_GET_TERMIOS 13
-#define SYS_SET_TERMIOS 14
-#define SYS_FORK 15
-#define SYS_EXEC 16
-#define SYS_SLEEP 17
-#define SYS_WAIT 18
-#define SYS_FSTAT 19
-#define SYS_READ_DIR_ENTRIES 21
-#define SYS_SET_UID 22
-#define SYS_SET_GID 23
-#define SYS_SET_EUID 24
-#define SYS_SET_EGID 25
-#define SYS_SET_REUID 26
-#define SYS_SET_REGID 27
-#define SYS_GET_UID 28
-#define SYS_GET_GID 29
-#define SYS_GET_EUID 30
-#define SYS_GET_EGID 31
-#define SYS_GET_PWD 32
-#define SYS_SET_PWD 33
-#define SYS_CLOCK_GETTIME 34
-#define SYS_PIPE 35
-#define SYS_DUP 36
-#define SYS_DUP2 37
-#define SYS_KILL 39
-#define SYS_SIGNAL 40
-#define SYS_TCSETPGRP 42
-#define SYS_GET_PID 43
-#define SYS_GET_PGID 44
-#define SYS_SET_PGID 45
-#define SYS_FCNTL 46
-#define SYS_NANOSLEEP 47
-#define SYS_FSTATAT 48
-#define SYS_STAT 49 // stat/lstat
-#define SYS_SYNC 50
-#define SYS_MMAP 51
-#define SYS_MUNMAP 52
-#define SYS_TTY_CTRL 53
-#define SYS_POWEROFF 54
-#define SYS_CHMOD 55
-#define SYS_CREATE 56 // creat, mkfifo
-#define SYS_CREATE_DIR 57 // mkdir
-#define SYS_UNLINK 58
-#define SYS_READLINK 59
-#define SYS_READLINKAT 60
-#define SYS_MSYNC 61
-#define SYS_PREAD 62
-#define SYS_CHOWN 63
-#define SYS_LOAD_KEYMAP 64
-#define SYS_SOCKET 65
-#define SYS_BIND 66
-#define SYS_SENDTO 67
-#define SYS_RECVFROM 68
-#define SYS_IOCTL 69
-#define SYS_ACCEPT 70
-#define SYS_CONNECT 71
-#define SYS_LISTEN 72
+#define __SYSCALL_LIST(O)					\
+	O(SYS_EXIT,				exit)			\
+	O(SYS_READ,				read)			\
+	O(SYS_WRITE,			write)			\
+	O(SYS_TERMID,			termid)			\
+	O(SYS_CLOSE,			close)			\
+	O(SYS_OPEN,				open)			\
+	O(SYS_OPENAT,			openat)			\
+	O(SYS_SEEK,				seek)			\
+	O(SYS_TELL,				tell)			\
+	O(SYS_GET_TERMIOS,		gettermios)		\
+	O(SYS_SET_TERMIOS,		settermios)		\
+	O(SYS_FORK,				fork)			\
+	O(SYS_EXEC,				exec)			\
+	O(SYS_SLEEP,			sleep)			\
+	O(SYS_WAIT,				wait)			\
+	O(SYS_FSTAT,			fstat)			\
+	O(SYS_READ_DIR,			readdir)		\
+	O(SYS_SET_UID,			setuid)			\
+	O(SYS_SET_GID,			setgid)			\
+	O(SYS_SET_EUID,			seteuid)		\
+	O(SYS_SET_EGID,			setegid)		\
+	O(SYS_SET_REUID,		setreuid)		\
+	O(SYS_SET_REGID,		setregid)		\
+	O(SYS_GET_UID,			getuid)			\
+	O(SYS_GET_GID,			getgid)			\
+	O(SYS_GET_EUID,			geteuid)		\
+	O(SYS_GET_EGID,			getegid)		\
+	O(SYS_GET_PWD,			getpwd)			\
+	O(SYS_SET_PWD,			setpwd)			\
+	O(SYS_CLOCK_GETTIME,	clock_gettime)	\
+	O(SYS_PIPE,				pipe)			\
+	O(SYS_DUP,				dup)			\
+	O(SYS_DUP2,				dup2)			\
+	O(SYS_KILL,				kill)			\
+	O(SYS_SIGNAL,			signal)			\
+	O(SYS_TCSETPGRP,		tcsetpgrp)		\
+	O(SYS_GET_PID,			getpid)			\
+	O(SYS_GET_PGID,			getpgid)		\
+	O(SYS_SET_PGID,			setpgid)		\
+	O(SYS_FCNTL,			fcntl)			\
+	O(SYS_NANOSLEEP,		nanosleep)		\
+	O(SYS_FSTATAT,			fstatat)		\
+	O(SYS_STAT,				stat)			\
+	O(SYS_SYNC,				sync)			\
+	O(SYS_MMAP,				mmap)			\
+	O(SYS_MUNMAP,			munmap) 		\
+	O(SYS_TTY_CTRL,			tty_ctrl)		\
+	O(SYS_POWEROFF,			poweroff)		\
+	O(SYS_CHMOD,			chmod)			\
+	O(SYS_CREATE,			create)			\
+	O(SYS_CREATE_DIR,		create_dir)		\
+	O(SYS_UNLINK,			unlink) 		\
+	O(SYS_READLINK,			readlink)		\
+	O(SYS_READLINKAT,		readlinkat)		\
+	O(SYS_MSYNC,			msync)			\
+	O(SYS_PREAD,			pread)			\
+	O(SYS_CHOWN,			chown)			\
+	O(SYS_LOAD_KEYMAP,		load_keymap)	\
+	O(SYS_SOCKET,			socket)			\
+	O(SYS_BIND,				bind)			\
+	O(SYS_SENDTO,			sendto)			\
+	O(SYS_RECVFROM,			recvfrom)		\
+	O(SYS_IOCTL,			ioctl)			\
+	O(SYS_ACCEPT,			accept)			\
+	O(SYS_CONNECT,			connect)		\
+	O(SYS_LISTEN,			listen)			\
+	O(SYS_PSELECT,			pselect)		\
+
+enum Syscall
+{
+#define O(enum, name) enum,
+	__SYSCALL_LIST(O)
+#undef O
+	__SYSCALL_COUNT
+};
 
 __END_DECLS
 

libc/include/sys/time.h

@@ -7,18 +7,10 @@
 
 __BEGIN_DECLS
 
-#define __need_time_t
-#define __need_suseconds_t
-#include <sys/types.h>
-
 // NOTE: select is declared from here
 #include <sys/select.h>
 
-struct timeval
-{
-	time_t		tv_sec;		/* Seconds. */
-	suseconds_t	tc_usec;	/* Microseconds. */
-};
+#include <bits/types/timeval.h>
 
 struct itimerval
 {

libc/sys/select.cpp

@@ -0,0 +1,31 @@
+#include <sys/select.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+int pselect(int nfds, fd_set* __restrict readfds, fd_set* __restrict writefds, fd_set* __restrict errorfds, const struct timespec* __restrict timeout, const sigset_t* __restrict sigmask)
+{
+	sys_pselect_t arguments {
+		.nfds = nfds,
+		.readfds = readfds,
+		.writefds = writefds,
+		.errorfds = errorfds,
+		.timeout = timeout,
+		.sigmask = sigmask
+	};
+	return syscall(SYS_PSELECT, &arguments);
+}
+
+int select(int nfds, fd_set* __restrict readfds, fd_set* __restrict writefds, fd_set* __restrict errorfds, struct timeval* __restrict timeout)
+{
+	timespec* pts = nullptr;
+	timespec ts;
+	if (timeout)
+	{
+		ts.tv_sec = timeout->tv_sec;
+		ts.tv_nsec = timeout->tc_usec * 1000;
+		pts = &ts;
+	}
+
+	// TODO: "select may update timeout", should we?
+	return pselect(nfds, readfds, writefds, errorfds, pts, nullptr);
+}

userspace/CMakeLists.txt

@@ -34,6 +34,9 @@ set(USERSPACE_PROJECTS
 	test-globals
 	test-mouse
 	test-sort
+	test-tcp
+	test-udp
+	test-unix-socket
 	touch
 	u8sum
 	whoami

userspace/nslookup/main.cpp

@@ -1,7 +1,12 @@
+#include <arpa/inet.h>
+#include <netinet/in.h>
 #include <stdio.h>
 #include <string.h>
 #include <sys/socket.h>
 #include <sys/un.h>
+#include <unistd.h>
+
+#define MAX(a, b) ((a) < (b) ? (b) : (a))
 
 int main(int argc, char** argv)
 {
@@ -33,15 +38,17 @@ int main(int argc, char** argv)
 		return 1;
 	}
 
-	char buffer[128];
-	ssize_t nrecv = recv(socket, buffer, sizeof(buffer), 0);
-	if (nrecv == -1)
+	sockaddr_storage storage;
+	if (recv(socket, &storage, sizeof(storage), 0) == -1)
 	{
 		perror("recv");
 		return 1;
 	}
-	buffer[nrecv] = '\0';
 
-	printf("%s\n", buffer);
+	close(socket);
+
+	char buffer[MAX(INET_ADDRSTRLEN, INET6_ADDRSTRLEN)];
+	printf("%s\n", inet_ntop(storage.ss_family, storage.ss_storage, buffer, sizeof(buffer)));
+
 	return 0;
 }

userspace/resolver/main.cpp

@@ -1,4 +1,5 @@
 #include <BAN/ByteSpan.h>
+#include <BAN/Debug.h>
 #include <BAN/Endianness.h>
 #include <BAN/HashMap.h>
 #include <BAN/IPv4.h>
@@ -39,6 +40,19 @@ struct DNSAnswer
 };
 static_assert(sizeof(DNSAnswer) == 12);
 
+enum QTYPE : uint16_t
+{
+	A		= 0x0001,
+	CNAME	= 0x0005,
+	AAAA	= 0x001C,
+};
+
+struct DNSEntry
+{
+	time_t				valid_until	{ 0 };
+	BAN::IPv4Address	address 	{ 0 };
+};
+
 bool send_dns_query(int socket, BAN::StringView domain, uint16_t id)
 {
 	static uint8_t buffer[4096];
@@ -61,8 +75,8 @@ bool send_dns_query(int socket, BAN::StringView domain, uint16_t id)
 	}
 	request.data[idx++] = 0x00;
 
-	*(uint16_t*)&request.data[idx] = htons(0x01); idx += 2;
-	*(uint16_t*)&request.data[idx] = htons(0x01); idx += 2;
+	*(uint16_t*)&request.data[idx] = htons(QTYPE::A); idx += 2;
+	*(uint16_t*)&request.data[idx] = htons(0x0001); idx += 2;
 
 	sockaddr_in nameserver;
 	nameserver.sin_family = AF_INET;
@@ -70,33 +84,33 @@ bool send_dns_query(int socket, BAN::StringView domain, uint16_t id)
 	nameserver.sin_addr.s_addr = inet_addr("8.8.8.8");
 	if (sendto(socket, &request, sizeof(DNSPacket) + idx, 0, (sockaddr*)&nameserver, sizeof(nameserver)) == -1)
 	{
-		perror("sendto");
+		dprintln("sendto: {}", strerror(errno));
 		return false;
 	}
 
 	return true;
 }
 
-BAN::Optional<BAN::String> read_dns_response(int socket, uint16_t id)
+BAN::Optional<DNSEntry> read_dns_response(int socket, uint16_t id)
 {
 	static uint8_t buffer[4096];
 
 	ssize_t nrecv = recvfrom(socket, buffer, sizeof(buffer), 0, nullptr, nullptr);
 	if (nrecv == -1)
 	{
-		perror("recvfrom");
+		dprintln("recvfrom: {}", strerror(errno));
 		return {};
 	}
 
 	DNSPacket& reply = *reinterpret_cast<DNSPacket*>(buffer);
 	if (reply.identification != id)
 	{
-		fprintf(stderr, "Reply to invalid packet\n");
+		dprintln("Reply to invalid packet");
 		return {};
 	}
 	if (reply.flags & 0x0F)
 	{
-		fprintf(stderr, "DNS error (rcode %u)\n", (unsigned)(reply.flags & 0xF));
+		dprintln("DNS error (rcode {})", (unsigned)(reply.flags & 0xF));
 		return {};
 	}
 
@@ -109,13 +123,22 @@ BAN::Optional<BAN::String> read_dns_response(int socket, uint16_t id)
 	}
 
 	DNSAnswer& answer = *reinterpret_cast<DNSAnswer*>(&reply.data[idx]);
+	if (answer.type() != QTYPE::A)
+	{
+		dprintln("Not A record");
+		return {};
+	}
 	if (answer.data_len() != 4)
 	{
-		fprintf(stderr, "Not IPv4\n");
+		dprintln("corrupted package");
 		return {};
 	}
 
-	return inet_ntoa({ .s_addr = *reinterpret_cast<uint32_t*>(answer.data) });
+	DNSEntry result;
+	result.valid_until	= time(nullptr) + answer.ttl();
+	result.address		= BAN::IPv4Address(*reinterpret_cast<uint32_t*>(answer.data));
+
+	return result;
 }
 
 int create_service_socket()
@@ -123,7 +146,7 @@ int create_service_socket()
 	int socket = ::socket(AF_UNIX, SOCK_SEQPACKET, 0);
 	if (socket == -1)
 	{
-		perror("socket");
+		dprintln("socket: {}", strerror(errno));
 		return -1;
 	}
 
@@ -132,21 +155,21 @@ int create_service_socket()
 	strcpy(addr.sun_path, "/tmp/resolver.sock");
 	if (bind(socket, (sockaddr*)&addr, sizeof(addr)) == -1)
 	{
-		perror("bind");
+		dprintln("bind: {}", strerror(errno));
 		close(socket);
 		return -1;
 	}
 
 	if (chmod("/tmp/resolver.sock", 0777) == -1)
 	{
-		perror("chmod");
+		dprintln("chmod: {}", strerror(errno));
 		close(socket);
 		return -1;
 	}
 
 	if (listen(socket, 10) == -1)
 	{
-		perror("listen");
+		dprintln("listen: {}", strerror(errno));
 		close(socket);
 		return -1;
 	}
@@ -160,7 +183,7 @@ BAN::Optional<BAN::String> read_service_query(int socket)
 	ssize_t nrecv = recv(socket, buffer, sizeof(buffer), 0);
 	if (nrecv == -1)
 	{
-		perror("recv");
+		dprintln("recv: {}", strerror(errno));
 		return {};
 	}
 	buffer[nrecv] = '\0';
@@ -178,39 +201,60 @@ int main(int, char**)
 	int dns_socket = socket(AF_INET, SOCK_DGRAM, 0);
 	if (dns_socket == -1)
 	{
-		perror("socket");
+		dprintln("socket: {}", strerror(errno));
 		return 1;
 	}
 
+	BAN::HashMap<BAN::String, DNSEntry> dns_cache;
+
 	for (;;)
 	{
 		int client = accept(service_socket, nullptr, nullptr);
 		if (client == -1)
 		{
-			perror("accept");
+			dprintln("accept: {}", strerror(errno));
 			continue;
 		}
 
 		auto query = read_service_query(client);
 		if (!query.has_value())
-			continue;
-
-		uint16_t id = rand() % 0xFFFF;
-
-		if (send_dns_query(dns_socket, *query, id))
 		{
-			auto response = read_dns_response(dns_socket, id);
-			if (response.has_value())
+			close(client);
+			continue;
+		}
+
+		BAN::Optional<DNSEntry> result;
+
+		if (dns_cache.contains(*query))
+		{
+			auto& cached = dns_cache[*query];
+			if (time(nullptr) <= cached.valid_until)
+				result = cached;
+			else
+				dns_cache.remove(*query);
+		}
+
+		if (!result.has_value())
+		{
+			uint16_t id = rand() % 0xFFFF;
+			if (send_dns_query(dns_socket, *query, id))
 			{
-				if (send(client, response->data(), response->size() + 1, 0) == -1)
-					perror("send");
-				close(client);
-				continue;
+				result = read_dns_response(dns_socket, id);
+				if (result.has_value())
+					(void)dns_cache.insert(*query, *result);
 			}
 		}
 
-		char message[] = "unavailable";
-		send(client, message, sizeof(message), 0);
+		if (!result.has_value())
+			result = DNSEntry { .valid_until = 0, .address = BAN::IPv4Address(INADDR_ANY) };
+
+		sockaddr_storage storage;
+		storage.ss_family = AF_INET;
+		memcpy(storage.ss_storage, &result->address.raw, sizeof(result->address.raw));
+
+		if (send(client, &storage, sizeof(storage), 0) == -1)
+			dprintln("send: {}", strerror(errno));
+
 		close(client);
 	}
 

userspace/test-tcp/CMakeLists.txt

@@ -0,0 +1,16 @@
+cmake_minimum_required(VERSION 3.26)
+
+project(test-tcp CXX)
+
+set(SOURCES
+	main.cpp
+)
+
+add_executable(test-tcp ${SOURCES})
+target_compile_options(test-tcp PUBLIC -O2 -g)
+target_link_libraries(test-tcp PUBLIC libc)
+
+add_custom_target(test-tcp-install
+	COMMAND ${CMAKE_COMMAND} -E copy ${CMAKE_CURRENT_BINARY_DIR}/test-tcp ${BANAN_BIN}/
+	DEPENDS test-tcp
+)

userspace/test-tcp/main.cpp

@@ -0,0 +1,111 @@
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+in_addr_t get_ipv4_address(const char* query)
+{
+	if (in_addr_t ipv4 = inet_addr(query); ipv4 != (in_addr_t)(-1))
+		return ipv4;
+
+	int socket = ::socket(AF_UNIX, SOCK_SEQPACKET, 0);
+	if (socket == -1)
+	{
+		perror("socket");
+		return -1;
+	}
+
+	sockaddr_un addr;
+	addr.sun_family = AF_UNIX;
+	strcpy(addr.sun_path, "/tmp/resolver.sock");
+	if (connect(socket, (sockaddr*)&addr, sizeof(addr)) == -1)
+	{
+		perror("connect");
+		close(socket);
+		return -1;
+	}
+
+	if (send(socket, query, strlen(query), 0) == -1)
+	{
+		perror("send");
+		close(socket);
+		return -1;
+	}
+
+	sockaddr_storage storage;
+	if (recv(socket, &storage, sizeof(storage), 0) == -1)
+	{
+		perror("recv");
+		close(socket);
+		return -1;
+	}
+
+	close(socket);
+
+	return *reinterpret_cast<in_addr_t*>(storage.ss_storage);
+}
+
+int main(int argc, char** argv)
+{
+	if (argc != 2)
+	{
+		fprintf(stderr, "usage: %s IPADDR\n", argv[0]);
+		return 1;
+	}
+
+	in_addr_t ipv4 = get_ipv4_address(argv[1]);
+	if (ipv4 == (in_addr_t)(-1))
+	{
+		fprintf(stderr, "could not parse address '%s'\n", argv[1]);
+		return 1;
+	}
+
+	int socket = ::socket(AF_INET, SOCK_STREAM, 0);
+	if (socket == -1)
+	{
+		perror("socket");
+		return 1;
+	}
+
+	printf("connecting to %s\n", inet_ntoa({ .s_addr = ipv4 }));
+
+	sockaddr_in server_addr;
+	server_addr.sin_family = AF_INET;
+	server_addr.sin_port = htons(80);
+	server_addr.sin_addr.s_addr = ipv4;
+	if (connect(socket, (sockaddr*)&server_addr, sizeof(server_addr)) == -1)
+	{
+		perror("connect");
+		return 1;
+	}
+
+	char request[128];
+	strcpy(request, "GET / HTTP/1.1\r\n");
+	strcat(request, "Host: "); strcat(request, argv[1]); strcat(request, "\r\n");
+	strcat(request, "Accept: */*\r\n");
+	strcat(request, "Connection: close\r\n");
+	strcat(request, "\r\n");
+	if (send(socket, request, strlen(request), 0) == -1)
+	{
+		perror("send");
+		return 1;
+	}
+
+	char buffer[1024];
+	for (;;)
+	{
+		ssize_t nrecv = recv(socket, buffer, sizeof(buffer), 0);
+		if (nrecv == -1)
+		{
+			perror("recv");
+			break;
+		}
+		write(STDOUT_FILENO, buffer, nrecv);
+	}
+
+	close(socket);
+	return 0;
+}

userspace/test-udp/CMakeLists.txt

@@ -0,0 +1,16 @@
+cmake_minimum_required(VERSION 3.26)
+
+project(test-udp CXX)
+
+set(SOURCES
+	main.cpp
+)
+
+add_executable(test-udp ${SOURCES})
+target_compile_options(test-udp PUBLIC -O2 -g)
+target_link_libraries(test-udp PUBLIC libc)
+
+add_custom_target(test-udp-install
+	COMMAND ${CMAKE_COMMAND} -E copy ${CMAKE_CURRENT_BINARY_DIR}/test-udp ${BANAN_BIN}/
+	DEPENDS test-udp
+)

userspace/test-udp/main.cpp

@@ -0,0 +1,88 @@
+#include <arpa/inet.h>
+#include <netinet/in.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <unistd.h>
+
+int usage(const char* argv0)
+{
+	fprintf(stderr, "usage: %s [-s|-c] [-a addr] [-p port]\n", argv0);
+	return 1;
+}
+
+int main(int argc, char** argv)
+{
+	bool server = false;
+	uint32_t addr = 0;
+	uint16_t port = 0;
+
+	for (int i = 1; i < argc; i++)
+	{
+		if (strcmp(argv[i], "-s") == 0)
+			server = true;
+		else if (strcmp(argv[i], "-c") == 0)
+			server = false;
+		else if (strcmp(argv[i], "-a") == 0)
+			addr = inet_addr(argv[++i]);
+		else if (strcmp(argv[i], "-p") == 0)
+			sscanf(argv[++i], "%hu", &port);
+		else
+			return usage(argv[0]);
+	}
+
+	int socket = ::socket(AF_INET, SOCK_DGRAM, 0);
+	if (socket == -1)
+	{
+		perror("socket");
+		return 1;
+	}
+
+	if (server)
+	{
+		sockaddr_in bind_addr;
+		bind_addr.sin_family = AF_INET;
+		bind_addr.sin_port = htons(port);
+		bind_addr.sin_addr.s_addr = addr;
+
+		if (bind(socket, (sockaddr*)&bind_addr, sizeof(bind_addr)) == -1)
+		{
+			perror("bind");
+			return 1;
+		}
+
+		printf("listening on %s:%hu\n", inet_ntoa(bind_addr.sin_addr), ntohs(bind_addr.sin_port));
+
+		char buffer[1024];
+		sockaddr_in sender;
+		socklen_t sender_len = sizeof(sender);
+
+		if (recvfrom(socket, buffer, sizeof(buffer), 0, (sockaddr*)&sender, &sender_len) == -1)
+		{
+			perror("recvfrom");
+			return 1;
+		}
+
+		printf("received from %s:%hu\n", inet_ntoa(sender.sin_addr), ntohs(sender.sin_port));
+		printf("  %s\n", buffer);
+	}
+	else
+	{
+		const char buffer[] = "Hello from banan-os!";
+
+		sockaddr_in server_addr;
+		server_addr.sin_family = AF_INET;
+		server_addr.sin_port = htons(port);
+		server_addr.sin_addr.s_addr = addr;
+
+		printf("sending to %s:%hu\n", inet_ntoa(server_addr.sin_addr), ntohs(server_addr.sin_port));
+		if (sendto(socket, buffer, sizeof(buffer), 0, (sockaddr*)&server_addr, sizeof(server_addr)) == -1)
+		{
+			perror("sendto");
+			return 1;
+		}
+	}
+
+	close(socket);
+	return 0;
+}

userspace/test-unix-socket/CMakeLists.txt

@@ -0,0 +1,16 @@
+cmake_minimum_required(VERSION 3.26)
+
+project(test-unix-socket CXX)
+
+set(SOURCES
+	main.cpp
+)
+
+add_executable(test-unix-socket ${SOURCES})
+target_compile_options(test-unix-socket PUBLIC -O2 -g)
+target_link_libraries(test-unix-socket PUBLIC libc)
+
+add_custom_target(test-unix-socket-install
+	COMMAND ${CMAKE_COMMAND} -E copy ${CMAKE_CURRENT_BINARY_DIR}/test-unix-socket ${BANAN_BIN}/
+	DEPENDS test-unix-socket
+)

userspace/test-unix-socket/main.cpp

@@ -0,0 +1,200 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#define SOCK_PATH "/tmp/test.sock"
+
+int server_connection()
+{
+	int socket = ::socket(AF_UNIX, SOCK_STREAM, 0);
+	if (socket == -1)
+	{
+		perror("server: socket");
+		return 1;
+	}
+
+	sockaddr_un addr;
+	addr.sun_family = AF_UNIX;
+	strcpy(addr.sun_path, SOCK_PATH);
+	if (bind(socket, (sockaddr*)&addr, sizeof(addr)))
+	{
+		perror("server: bind");
+		return 1;
+	}
+
+	if (listen(socket, 0) == -1)
+	{
+		perror("server: listen");
+		return 1;
+	}
+
+	int client = accept(socket, nullptr, nullptr);
+	if (client == -1)
+	{
+		perror("server: accept");
+		return 1;
+	}
+
+	sleep(2);
+
+	char buffer[128];
+	ssize_t nrecv = recv(client, buffer, sizeof(buffer), 0);
+	if (nrecv == -1)
+	{
+		perror("server: recv");
+		return 1;
+	}
+
+	printf("server: read %d bytes\n", (int)nrecv);
+	printf("server:   '%s'\n", buffer);
+
+	char message[] = "Hello from server";
+	if (send(client, message, sizeof(message), 0) == -1)
+	{
+		perror("server: send");
+		return 1;
+	}
+
+	close(client);
+	close(socket);
+	return 0;
+}
+
+int client_connection()
+{
+	sleep(1);
+
+	int socket = ::socket(AF_UNIX, SOCK_STREAM, 0);
+	if (socket == -1)
+	{
+		perror("client: socket");
+		return 1;
+	}
+
+	sockaddr_un addr;
+	addr.sun_family = AF_UNIX;
+	strcpy(addr.sun_path, SOCK_PATH);
+	if (connect(socket, (sockaddr*)&addr, sizeof(addr)) == -1)
+	{
+		perror("client: connect");
+		return 1;
+	}
+
+	char message[] = "Hello from client";
+	if (send(socket, message, sizeof(message), 0) == -1)
+	{
+		perror("client: send");
+		return 1;
+	}
+
+	char buffer[128];
+	ssize_t nrecv = recv(socket, buffer, sizeof(buffer), 0);
+	if (nrecv == -1)
+	{
+		perror("client: recv");
+		return 1;
+	}
+
+	printf("client: read %d bytes\n", (int)nrecv);
+	printf("client:   '%s'\n", buffer);
+
+	close(socket);
+	return 0;
+}
+
+int server_connectionless()
+{
+	int socket = ::socket(AF_UNIX, SOCK_DGRAM, 0);
+	if (socket == -1)
+	{
+		perror("server: socket");
+		return 1;
+	}
+
+	sockaddr_un addr;
+	addr.sun_family = AF_UNIX;
+	strcpy(addr.sun_path, SOCK_PATH);
+	if (bind(socket, (sockaddr*)&addr, sizeof(addr)))
+	{
+		perror("server: bind");
+		return 1;
+	}
+
+	sleep(2);
+
+	char buffer[128];
+	ssize_t nrecv = recv(socket, buffer, sizeof(buffer), 0);
+	if (nrecv == -1)
+	{
+		perror("server: recv");
+		return 1;
+	}
+
+	close(socket);
+	return 0;
+}
+
+int client_connectionless()
+{
+	sleep(1);
+
+	int socket = ::socket(AF_UNIX, SOCK_DGRAM, 0);
+	if (socket == -1)
+	{
+		perror("client: socket");
+		return 1;
+	}
+
+	sockaddr_un addr;
+	addr.sun_family = AF_UNIX;
+	strcpy(addr.sun_path, SOCK_PATH);
+	char message[] = "Hello from client";
+	if (sendto(socket, message, sizeof(message), 0, (sockaddr*)&addr, sizeof(addr)) == -1)
+	{
+		perror("client: send");
+		return 1;
+	}
+
+	close(socket);
+	return 0;
+}
+
+int test_mode(int (*client)(), int (*server)())
+{
+	pid_t pid = fork();
+	if (pid == -1)
+	{
+		perror("fork");
+		return 1;
+	}
+
+	if (pid == 0)
+		exit(server());
+
+	if (int ret = client())
+	{
+		kill(pid, SIGKILL);
+		return ret;
+	}
+
+	int ret;
+	waitpid(pid, &ret, 0);
+
+	if (remove(SOCK_PATH) == -1)
+		perror("remove");
+
+	return ret;
+}
+
+int main()
+{
+	if (test_mode(client_connection, server_connection))
+		return 1;
+	if (test_mode(client_connectionless, server_connectionless))
+		return 2;
+	return 0;
+}