LibCore: Implement UDPServer on Windows

Author: https://github.com/ayeteadoe
Commit: 904f736b95
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/5435
Reviewed-by: https://github.com/ADKaster ✅
Reviewed-by: https://github.com/R-Goc

Libraries/LibCore/CMakeLists.txt

@@ -58,11 +58,11 @@ set(SOURCES
 )
 
 if (WIN32)
-    # FIXME: Support UDPServer on Windows
     list(APPEND SOURCES
         SocketWindows.cpp
         AnonymousBufferWindows.cpp
         EventLoopImplementationWindows.cpp
+        UDPServerWindows.cpp
         TCPServerWindows.cpp)
 else()
     list(APPEND SOURCES

Libraries/LibCore/SystemWindows.cpp

@@ -270,6 +270,22 @@ ErrorOr<int> accept(int sockfd, struct sockaddr* addr, socklen_t* addr_size)
     return fd;
 }
 
+ErrorOr<ssize_t> sendto(int sockfd, void const* source, size_t source_length, int flags, struct sockaddr const* destination, socklen_t destination_length)
+{
+    auto sent = ::sendto(sockfd, static_cast<char const*>(source), source_length, flags, destination, destination_length);
+    if (sent == SOCKET_ERROR)
+        return Error::from_windows_error();
+    return sent;
+}
+
+ErrorOr<ssize_t> recvfrom(int sockfd, void* buffer, size_t buffer_length, int flags, struct sockaddr* address, socklen_t* address_length)
+{
+    auto received = ::recvfrom(sockfd, static_cast<char*>(buffer), buffer_length, flags, address, address_length);
+    if (received == SOCKET_ERROR)
+        return Error::from_windows_error();
+    return received;
+}
+
 ErrorOr<void> getsockname(int sockfd, struct sockaddr* name, socklen_t* name_size)
 {
     if (::getsockname(sockfd, name, name_size) == SOCKET_ERROR)

Libraries/LibCore/UDPServerWindows.cpp

@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2025, ayeteadoe <ayeteadoe@gmail.com>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/IPv4Address.h>
+#include <AK/Types.h>
+#include <LibCore/Notifier.h>
+#include <LibCore/Socket.h>
+#include <LibCore/System.h>
+#include <LibCore/UDPServer.h>
+
+#include <AK/Windows.h>
+
+namespace Core {
+
+UDPServer::UDPServer(EventReceiver* parent)
+    : EventReceiver(parent)
+{
+    m_fd = MUST(Core::System::socket(AF_INET, SOCK_DGRAM, 0));
+    int option = 1;
+    MUST(Core::System::ioctl(m_fd, FIONBIO, option));
+    auto const ret = SetHandleInformation(to_handle(m_fd), HANDLE_FLAG_INHERIT, 0);
+    VERIFY(ret != 0);
+}
+
+UDPServer::~UDPServer()
+{
+    MUST(Core::System::close(m_fd));
+}
+
+bool UDPServer::bind(IPv4Address const& address, u16 port)
+{
+    if (m_bound)
+        return false;
+
+    auto socket_address = SocketAddress(address, port);
+    auto in = socket_address.to_sockaddr_in();
+    auto bind_result = Core::System::bind(m_fd, (sockaddr const*)&in, sizeof(in));
+    if (bind_result.is_error()) {
+        perror("UDPServer::bind");
+        return false;
+    }
+
+    m_bound = true;
+
+    m_notifier = Notifier::construct(m_fd, Notifier::Type::Read, this);
+    m_notifier->on_activation = [this] {
+        if (on_ready_to_receive)
+            on_ready_to_receive();
+    };
+    return true;
+}
+
+ErrorOr<ByteBuffer> UDPServer::receive(size_t size, sockaddr_in& in)
+{
+    auto buf = TRY(ByteBuffer::create_uninitialized(size));
+    socklen_t in_len = sizeof(in);
+    auto bytes_received = TRY(Core::System::recvfrom(m_fd, buf.data(), size, 0, (sockaddr*)&in, &in_len));
+    buf.resize(bytes_received);
+    return buf;
+}
+
+ErrorOr<size_t> UDPServer::send(ReadonlyBytes buffer, sockaddr_in const& to)
+{
+    socklen_t to_len = sizeof(to);
+    return TRY(Core::System::sendto(m_fd, buffer.data(), buffer.size(), 0, (sockaddr const*)&to, to_len));
+}
+
+Optional<IPv4Address> UDPServer::local_address() const
+{
+    if (m_fd == -1)
+        return {};
+
+    sockaddr_in address;
+    socklen_t len = sizeof(address);
+    if (Core::System::getsockname(m_fd, (sockaddr*)&address, &len).is_error())
+        return {};
+
+    return IPv4Address(address.sin_addr.s_addr);
+}
+
+Optional<u16> UDPServer::local_port() const
+{
+    if (m_fd == -1)
+        return {};
+
+    sockaddr_in address;
+    socklen_t len = sizeof(address);
+    if (Core::System::getsockname(m_fd, (sockaddr*)&address, &len).is_error())
+        return {};
+
+    return ntohs(address.sin_port);
+}
+
+}