LibCore: Add CTCPServer

This is pretty much a find/replace copy of CLocalServer, and some
modifications to CTCPSocket and CSocketAddress to support it.

Libraries/LibCore/CTCPServer.cpp

@@ -0,0 +1,55 @@
+#include <AK/IPv4Address.h>
+#include <AK/Types.h>
+#include <LibCore/CTCPServer.h>
+#include <LibCore/CTCPSocket.h>
+#include <LibCore/CNotifier.h>
+#include <stdio.h>
+#include <sys/socket.h>
+
+CTCPServer::CTCPServer(CObject* parent)
+    : CObject(parent)
+{
+    m_fd = socket(AF_INET, SOCK_STREAM | SOCK_NONBLOCK | SOCK_CLOEXEC, 0);
+    ASSERT(m_fd >= 0);
+}
+
+CTCPServer::~CTCPServer()
+{
+}
+
+bool CTCPServer::listen(const IPv4Address& address, u16 port)
+{
+    if (m_listening)
+        return false;
+
+    int rc;
+    auto socket_address = CSocketAddress(address, port);
+    auto in = socket_address.to_sockaddr_in();
+    rc = ::bind(m_fd, (const sockaddr*)&in, sizeof(in));
+    ASSERT(rc == 0);
+
+    rc = ::listen(m_fd, 5);
+    ASSERT(rc == 0);
+    m_listening = true;
+
+    m_notifier = make<CNotifier>(m_fd, CNotifier::Event::Read);
+    m_notifier->on_ready_to_read = [this] {
+        if (on_ready_to_accept)
+            on_ready_to_accept();
+    };
+    return true;
+}
+
+CTCPSocket* CTCPServer::accept()
+{
+    ASSERT(m_listening);
+    sockaddr_in in;
+    socklen_t in_size = sizeof(in);
+    int accepted_fd = ::accept(m_fd, (sockaddr*)&in, &in_size);
+    if (accepted_fd < 0) {
+        perror("accept");
+        return nullptr;
+    }
+
+    return new CTCPSocket({}, accepted_fd);
+}