Kernel: Basic userspace socket functionality

Can only receive UDP packets so far. Much work remains to be done

Author: byteduck

kernel/CMakeLists.txt

@@ -164,6 +164,7 @@ SET(KERNEL_SRCS
         syscall/read_write.cpp
         syscall/sigaction.cpp
         syscall/sleep.cpp
+        syscall/socket.cpp
         syscall/stat.cpp
         syscall/thread.cpp
         syscall/truncate.cpp
@@ -174,7 +175,10 @@ SET(KERNEL_SRCS
         StackWalker.cpp
         net/NetworkAdapter.cpp
         net/E1000Adapter.cpp
-        net/NetworkManager.cpp)
+        net/NetworkManager.cpp
+        net/Socket.cpp
+        net/IPSocket.cpp
+        net/UDPSocket.cpp)
 
 add_custom_command(
         OUTPUT "${CMAKE_CURRENT_BINARY_DIR}/generated/duckos_version.h"

kernel/api/in.h

@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/* Copyright © 2016-2024 Byteduck */
+
+#pragma once
+
+#include "socket.h"
+
+__DECL_BEGIN
+
+typedef uint16_t in_port_t;
+typedef uint32_t in_addr_t;
+
+struct in_addr {
+	in_addr_t s_addr;
+};
+
+struct sockaddr_in {
+	sa_family_t     sin_family;
+	in_port_t       sin_port;
+	struct in_addr  sin_addr;
+};
+
+# define INADDR_ANY ((uint32_t) 0x00000000)
+# define INADDR_NONE    0xffffffff
+# define INPORT_ANY 0
+#define IPPROTO_TCP 0
+#define IPPROTO_UDP 0
+
+__DECL_END

kernel/api/ipv4.h

@@ -11,6 +11,13 @@ class __attribute__((packed)) IPv4Address {
 public:
 	constexpr IPv4Address() = default;
 
+	constexpr IPv4Address(uint32_t addr) {
+		m_data[0] = addr >> 24;
+		m_data[1] = addr >> 16;
+		m_data[2] = addr >> 8;
+		m_data[3] = addr;
+	}
+
 	constexpr IPv4Address(uint8_t a, uint8_t b, uint8_t c, uint8_t d) {
 		m_data[0] = a;
 		m_data[1] = b;

kernel/api/socket.h

@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/* Copyright © 2016-2024 Byteduck */
+
+#pragma once
+
+#include "cdefs.h"
+#include "types.h"
+#include "un.h"
+
+__DECL_BEGIN
+
+// Domains
+#define AF_UNSPEC   0
+#define AF_UNIX     1
+#define AF_LOCAL    2
+#define AF_INET     3
+#define AF_PACKET   4
+
+// Types
+#define SOCK_STREAM  1
+#define SOCK_DGRAM   2
+#define SOCK_RAW     3
+
+typedef uint16_t sa_family_t;
+typedef uint32_t socklen_t;
+
+struct sockaddr {
+	sa_family_t sa_family;
+	char        sa_data[14];
+};
+
+struct iovec {
+	void*   iov_base;
+	size_t  iov_len;
+};
+
+struct msghdr {
+	void*          msg_name;
+	socklen_t      msg_namelen;
+	struct iovec*  msg_iov;
+	size_t         msg_iovlen;
+	void*          msg_control;
+	size_t         msg_controllen;
+	int            msg_flags;
+};
+
+struct sockaddr_storage {
+	sa_family_t ss_family;
+	struct sockaddr_un __un;
+};
+
+__DECL_END

kernel/api/udp.h

@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/* Copyright © 2016-2024 Byteduck */
+
+#pragma once
+
+#include "endian.h"
+
+struct UDPPacket {
+	BigEndian<uint16_t> source_port;
+	BigEndian<uint16_t> dest_port;
+	BigEndian<uint16_t> len;
+	BigEndian<uint16_t> checksum = 0;
+	uint8_t payload[];
+} __attribute__((packed));
+
+static_assert(sizeof(UDPPacket) == 8);

kernel/api/un.h

@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/* Copyright © 2016-2024 Byteduck */
+
+#pragma once
+
+#include "types.h"
+
+__DECL_BEGIN
+
+#define UNIX_PATH_MAX 100
+
+struct sockaddr_un {
+	uint16_t sun_family;
+	char sun_path[UNIX_PATH_MAX];
+};
+
+__DECL_END

kernel/filesystem/File.cpp

@@ -52,6 +52,10 @@ bool File::is_fifo() {
 	return false;
 }
 
+bool File::is_socket() {
+	return false;
+}
+
 ssize_t File::read(FileDescriptor &fd, size_t offset, SafePointer<uint8_t> buffer, size_t count) {
 	return 0;
 }

kernel/filesystem/File.h

@@ -37,6 +37,7 @@ class File {
 	virtual bool is_pty_mux();
 	virtual bool is_pty();
 	virtual bool is_fifo();
+	virtual bool is_socket();
 	virtual int ioctl(unsigned request, SafePointer<void*> argp);
 	virtual void open(FileDescriptor& fd, int options);
 	virtual void close(FileDescriptor& fd);

kernel/kstd/ListQueue.h

@@ -0,0 +1,70 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/* Copyright © 2016-2024 Byteduck */
+
+#pragma once
+
+#include "types.h"
+#include "Optional.h"
+
+namespace kstd {
+
+template<typename T, size_t max_count>
+class ListQueue {
+public:
+	ListQueue() = default;
+
+	bool enqueue(const T& val) {
+		if (m_count >= max_count)
+			return false;
+
+		if (m_tail == nullptr) {
+			m_head = new Entry {nullptr, val};
+			m_head = m_tail;
+		} else {
+			m_tail->next = new Entry {nullptr, val};
+			m_tail = m_tail->next;
+		}
+
+		m_count++;
+
+		return true;
+	}
+
+	Optional<T> dequeue() {
+		if (!m_head)
+			return nullopt;
+
+		m_count--;
+		auto* ent = m_head;
+		m_head = ent->next;
+		if (m_tail == ent)
+			m_tail = nullptr;
+		return ent->val;
+	}
+
+	Optional<T> peek() {
+		if (!m_head)
+			return nullopt;
+		return m_head->val;
+	}
+
+	[[nodiscard]] bool empty() const {
+		return m_count == 0;
+	}
+
+	[[nodiscard]] size_t count() const {
+		return count;
+	}
+
+private:
+	struct Entry {
+		Entry* next;
+		T val;
+	};
+
+	Entry* m_head = nullptr;
+	Entry* m_tail = nullptr;
+	size_t m_count = 0;
+};
+
+}

kernel/memory/SafePointer.h

@@ -9,6 +9,7 @@
 template<typename T>
 class SafePointer {
 public:
+	SafePointer() = default;
 	explicit SafePointer(T* raw_ptr, bool is_user):
 		m_ptr(raw_ptr), m_is_user(is_user) {}
 	template<typename C> SafePointer(const SafePointer<C>& safe_ptr):
@@ -153,9 +154,14 @@ class SafePointer {
 		});
 	}
 
+	template<typename R>
+	SafePointer<R> as() {
+		return SafePointer<R>((R*) m_ptr, m_is_user);
+	}
+
 private:
-	T* const m_ptr;
-	const bool m_is_user;
+	T* const m_ptr = nullptr;
+	const bool m_is_user = false;
 };
 
 template<typename T>

kernel/net/IPSocket.cpp

@@ -0,0 +1,87 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/* Copyright © 2016-2024 Byteduck */
+
+#include "IPSocket.h"
+#include "UDPSocket.h"
+#include "../api/in.h"
+#include "../kstd/KLog.h"
+#include "../tasking/PollBlocker.h"
+#include "../filesystem/FileDescriptor.h"
+
+IPSocket::IPSocket(Socket::Type type, int protocol): Socket(Domain::Inet, type, protocol) {
+
+}
+
+ResultRet<kstd::Arc<IPSocket>> IPSocket::make(Socket::Type type, int protocol) {
+	switch (type) {
+	case Type::Dgram:
+		return kstd::static_pointer_cast<IPSocket>(TRY(UDPSocket::make()));
+	default:
+		return Result(EINVAL);
+	}
+}
+
+Result IPSocket::bind(SafePointer<sockaddr> addr_ptr, socklen_t addrlen) {
+	if (m_bound || addrlen != sizeof(sockaddr_in))
+		return Result(set_error(EINVAL));
+
+	auto addr = addr_ptr.as<sockaddr_in>().get();
+	if (addr.sin_family != AF_INET)
+		return Result(set_error(EINVAL));
+
+	m_port = from_big_endian(addr.sin_port);
+	m_addr = IPv4Address(from_big_endian(addr.sin_addr.s_addr));
+
+	return do_bind();
+}
+
+ssize_t IPSocket::recvfrom(FileDescriptor& fd, SafePointer<uint8_t> buf, size_t len, int flags, SafePointer<sockaddr> src_addr, SafePointer<socklen_t> addrlen) {
+	m_receive_queue_lock.acquire();
+
+	// Block until we have a packet to read
+	while (m_receive_queue.empty()) {
+		if (fd.nonblock()) {
+			m_receive_queue_lock.release();
+			return -EAGAIN;
+		}
+
+		update_blocker();
+		m_receive_queue_lock.release();
+		TaskManager::current_thread()->block(m_receive_blocker);
+		m_receive_queue_lock.acquire();
+	}
+
+	// Read our packet
+	auto* packet = m_receive_queue.pop_front();
+	update_blocker();
+	m_receive_queue_lock.release();
+	auto res = do_recv(packet, buf, len);
+	kfree(packet);
+	return res;
+}
+
+Result IPSocket::recv_packet(const void* buf, size_t len) {
+	LOCK(m_receive_queue_lock);
+
+	if (m_receive_queue.size() == m_receive_queue.capacity()) {
+		KLog::warn("IPSocket", "Dropping packet because receive queue is full");
+		return Result(ENOSPC);
+	}
+
+	auto* src_pkt = (const IPv4Packet*) buf;
+	auto* new_pkt = (IPv4Packet*) kmalloc(len);
+	memcpy(new_pkt, src_pkt, len);
+
+	m_receive_queue.push_back(new_pkt);
+	update_blocker();
+
+	return Result(SUCCESS);
+}
+
+bool IPSocket::can_read(const FileDescriptor& fd) {
+	return !m_receive_queue.empty();
+}
+
+void IPSocket::update_blocker() {
+	m_receive_blocker.set_ready(!m_receive_queue.empty());
+}

kernel/net/IPSocket.h

@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/* Copyright © 2016-2024 Byteduck */
+
+#pragma once
+
+#include "Socket.h"
+#include "../api/ipv4.h"
+#include "../kstd/ListQueue.h"
+
+class IPSocket: public Socket {
+public:
+	static ResultRet<kstd::Arc<IPSocket>> make(Socket::Type type, int protocol);
+
+	// Socket
+	Result bind(SafePointer<sockaddr> addr, socklen_t addrlen) override;
+	ssize_t recvfrom(FileDescriptor &fd, SafePointer<uint8_t> buf, size_t len, int flags, SafePointer<sockaddr> src_addr, SafePointer<socklen_t> addrlen) override;
+	Result recv_packet(const void* buf, size_t len) override;
+
+	// File
+	bool can_read(const FileDescriptor &fd) override;
+
+protected:
+	IPSocket(Socket::Type type, int protocol);
+
+	virtual ssize_t do_recv(const IPv4Packet* pkt, SafePointer<uint8_t> buf, size_t len) = 0;
+	virtual Result do_bind() = 0;
+
+	void update_blocker();
+
+	bool m_bound = false;
+	uint16_t m_port;
+	IPv4Address m_addr;
+	kstd::circular_queue<IPv4Packet*> m_receive_queue { 16 };
+	Mutex m_receive_queue_lock { "IPSocket::receive_queue" };
+	BooleanBlocker m_receive_blocker;
+};