Kernel: Fix how socket closing works

Sockets are now closed only when they are not referenced any more. This
allows child process to close socket and still keep it open for the
parent.

kernel/include/kernel/FS/Inode.h

@@ -86,8 +86,6 @@ namespace Kernel
 		virtual bool is_pipe() const { return false; }
 		virtual bool is_tty() const { return false; }
 
-		void on_close();
-
 		// Directory API
 		BAN::ErrorOr<BAN::RefPtr<Inode>> find_inode(BAN::StringView);
 		BAN::ErrorOr<size_t> list_next_inodes(off_t, struct dirent* list, size_t list_size);
@@ -122,8 +120,6 @@ namespace Kernel
 		BAN::ErrorOr<long> ioctl(int request, void* arg);
 
 	protected:
-		virtual void on_close_impl() {}
-
 		// Directory API
 		virtual BAN::ErrorOr<BAN::RefPtr<Inode>> find_inode_impl(BAN::StringView)				{ return BAN::Error::from_errno(ENOTSUP); }
 		virtual BAN::ErrorOr<size_t> list_next_inodes_impl(off_t, struct dirent*, size_t)		{ return BAN::Error::from_errno(ENOTSUP); }

kernel/include/kernel/Networking/TCPSocket.h

@@ -49,8 +49,6 @@ namespace Kernel
 		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;
@@ -111,6 +109,7 @@ namespace Kernel
 		TCPSocket(NetworkLayer&, ino_t, const TmpInodeInfo&);
 		void process_task();
 
+		void start_close_sequence();
 		void set_connection_as_closed();
 
 	private:

kernel/include/kernel/Networking/UDPSocket.h

@@ -33,8 +33,6 @@ namespace Kernel
 	protected:
 		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;
@@ -45,6 +43,7 @@ namespace Kernel
 
 	private:
 		UDPSocket(NetworkLayer&, ino_t, const TmpInodeInfo&);
+		~UDPSocket();
 
 		struct PacketInfo
 		{

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

@@ -18,8 +18,6 @@ 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;
@@ -33,7 +31,7 @@ namespace Kernel
 
 	private:
 		UnixDomainSocket(SocketType, ino_t, const TmpInodeInfo&);
-		~UnixDomainSocket() { on_close_impl(); }
+		~UnixDomainSocket();
 
 		BAN::ErrorOr<void> add_packet(BAN::ConstByteSpan);
 

kernel/kernel/FS/Inode.cpp

@@ -56,12 +56,6 @@ namespace Kernel
 		return true;
 	}
 
-	void Inode::on_close()
-	{
-		LockGuard _(m_mutex);
-		on_close_impl();
-	}
-
 	BAN::ErrorOr<BAN::RefPtr<Inode>> Inode::find_inode(BAN::StringView name)
 	{
 		LockGuard _(m_mutex);

kernel/kernel/Networking/TCPSocket.cpp

@@ -63,39 +63,6 @@ namespace Kernel
 	{
 		ASSERT(!is_bound());
 		ASSERT(m_process == nullptr);
-		dprintln_if(DEBUG_TCP, "socket destroyed");
-	}
-
-	void TCPSocket::on_close_impl()
-	{
-		LockGuard _(m_mutex);
-
-		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)
@@ -407,6 +374,38 @@ namespace Kernel
 
 		m_semaphore.unblock();
 	}
+	
+	void TCPSocket::start_close_sequence()
+	{
+		LockGuard _(m_mutex);
+
+		if (!is_bound())
+			return;
+
+		switch (m_state)
+		{
+			case State::Established:
+				break;
+			case State::SynSent:
+				set_connection_as_closed();
+				return;
+			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");
+	}
 
 	void TCPSocket::set_connection_as_closed()
 	{
@@ -427,13 +426,25 @@ namespace Kernel
 		static constexpr uint32_t retransmit_timeout_ms = 1000;
 
 		BAN::RefPtr<TCPSocket> keep_alive = this;
+		bool started_close_sequence = false;
 
 		while (m_process)
 		{
-			uint64_t current_ms = SystemTimer::get().ms_since_boot();
+			const 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();
+				continue;
+			}
+
+			// This is the last instance
+			if (!started_close_sequence && ref_count() == 1)
+			{
+				start_close_sequence();
+				started_close_sequence = true;
+				continue;
+			}
 
 			{
 				LockGuard _(m_mutex);

kernel/kernel/Networking/UDPSocket.cpp

@@ -23,7 +23,7 @@ namespace Kernel
 		: NetworkSocket(network_layer, ino, inode_info)
 	{ }
 
-	void UDPSocket::on_close_impl()
+	UDPSocket::~UDPSocket()
 	{
 		if (is_bound())
 			m_network_layer.unbind_socket(this, m_port);

kernel/kernel/Networking/UNIX/Socket.cpp

@@ -47,7 +47,7 @@ namespace Kernel
 		}
 	}
 
-	void UnixDomainSocket::on_close_impl()
+	UnixDomainSocket::~UnixDomainSocket()
 	{
 		if (is_bound() && !is_bound_to_unused())
 		{

kernel/kernel/OpenFileDescriptorSet.cpp

@@ -317,8 +317,6 @@ namespace Kernel
 		if (m_open_files[fd]->flags & O_WRONLY && m_open_files[fd]->inode->is_pipe())
 			((Pipe*)m_open_files[fd]->inode.ptr())->close_writing();
 
-		m_open_files[fd]->inode->on_close();
-
 		m_open_files[fd].clear();
 
 		return {};