Introduce CIPCServerSideClient

As a new base class of IPC connections server-side.
Port ASClientConnection to CIPCServerSideClient.

1 files changed, 206 insertions, 0 deletions

diff --git a/Libraries/LibCore/CIPCServerSideClient.h b/Libraries/LibCore/CIPCServerSideClient.h
new file mode 100644
index 0000000000..9e09dedd87
--- /dev/null
+++ b/Libraries/LibCore/CIPCServerSideClient.h
@@ -0,0 +1,206 @@
+#pragma once
+
+#include <LibCore/CObject.h>
+#include <LibCore/CEvent.h>
+#include <LibCore/CEventLoop.h>
+#include <LibCore/CIODevice.h>
+#include <LibCore/CNotifier.h>
+
+#include <errno.h>
+#include <unistd.h>
+#include <sys/uio.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <stdio.h>
+
+class CIPCServerEvent : public CEvent {
+public:
+    enum Type {
+        Invalid = 2000,
+        ClientDisconnected,
+    };
+    CIPCServerEvent() {}
+    explicit CIPCServerEvent(Type type)
+        : CEvent(type)
+    {
+    }
+};
+
+class ASClientDisconnectedNotification : public CIPCServerEvent {
+public:
+    explicit ASClientDisconnectedNotification(int client_id)
+        : CIPCServerEvent(ClientDisconnected)
+        , m_client_id(client_id)
+    {
+    }
+
+    int client_id() const { return m_client_id; }
+
+private:
+    int m_client_id { 0 };
+};
+
+template <typename T, class... Args>
+T* CIPCServerSideClientCreator(Args&& ... args)
+{
+    auto conn = new T(AK::forward<Args>(args)...) /* arghs */;
+    conn->send_greeting();
+    return conn;
+};
+
+template <typename ServerMessage, typename ClientMessage>
+class CIPCServerSideClient : public CObject
+{
+public:
+    CIPCServerSideClient(int fd, int client_id)
+        : m_socket(fd)
+        , m_notifier(CNotifier(fd, CNotifier::Read))
+        , m_client_id(client_id)
+    {
+        m_notifier.on_ready_to_read = [this] { drain_client(); };
+        dbg() << "********** S: Created new CIPCServerSideClient " << fd << client_id << " and said hello";
+    }
+
+    ~CIPCServerSideClient()
+    {
+        dbg() << "********** S: Destroyed CIPCServerSideClient " << m_socket.fd() << client_id();
+    }
+
+    void post_message(const ServerMessage& message, const ByteBuffer& extra_data = {})
+    {
+        if (!extra_data.is_empty())
+            const_cast<ServerMessage&>(message).extra_size = extra_data.size();
+
+        struct iovec iov[2];
+        int iov_count = 1;
+
+        iov[0].iov_base = const_cast<ServerMessage*>(&message);
+        iov[0].iov_len = sizeof(message);
+
+        if (!extra_data.is_empty()) {
+            iov[1].iov_base = const_cast<u8*>(extra_data.data());
+            iov[1].iov_len = extra_data.size();
+            ++iov_count;
+        }
+
+        int nwritten = writev(m_socket.fd(), iov, iov_count);
+        if (nwritten < 0) {
+            switch (errno) {
+            case EPIPE:
+                dbgprintf("WSClientConnection::post_message: Disconnected from peer.\n");
+                delete_later();
+                return;
+                break;
+            case EAGAIN:
+                dbgprintf("WSClientConnection::post_message: Client buffer overflowed.\n");
+                did_misbehave();
+                return;
+                break;
+            default:
+                perror("WSClientConnection::post_message writev");
+                ASSERT_NOT_REACHED();
+            }
+        }
+
+        ASSERT(nwritten == (int)(sizeof(message) + extra_data.size()));
+    }
+
+    void drain_client()
+    {
+        unsigned messages_received = 0;
+        for (;;) {
+            ClientMessage message;
+            // FIXME: Don't go one message at a time, that's so much context switching, oof.
+            ssize_t nread = recv(m_socket.fd(), &message, sizeof(ClientMessage), MSG_DONTWAIT);
+            if (nread == 0 || (nread == -1 && errno == EAGAIN)) {
+                if (!messages_received) {
+                    // TODO: is delete_later() sufficient?
+                    CEventLoop::current().post_event(*this, make<ASClientDisconnectedNotification>(client_id()));
+                }
+                break;
+            }
+            if (nread < 0) {
+                perror("recv");
+                ASSERT_NOT_REACHED();
+            }
+            ByteBuffer extra_data;
+            if (message.extra_size) {
+                if (message.extra_size >= 32768) {
+                    dbgprintf("message.extra_size is way too large\n");
+                    return did_misbehave();
+                }
+                extra_data = ByteBuffer::create_uninitialized(message.extra_size);
+                // FIXME: We should allow this to time out. Maybe use a socket timeout?
+                int extra_nread = read(m_socket.fd(), extra_data.data(), extra_data.size());
+                if (extra_nread != (int)message.extra_size) {
+                    dbgprintf("extra_nread(%d) != extra_size(%d)\n", extra_nread, extra_data.size());
+                    if (extra_nread < 0)
+                        perror("read");
+                    return did_misbehave();
+                }
+            }
+            if (!handle_message(message, move(extra_data)))
+                return;
+            ++messages_received;
+        }
+    }
+
+    void did_misbehave()
+    {
+        dbgprintf("CIPCServerSideClient{%p} (id=%d, pid=%d) misbehaved, disconnecting.\n", this, client_id(), m_pid);
+        delete_later();
+        m_notifier.set_enabled(false);
+    }
+
+    const char* class_name() const override { return "CIPCServerSideClient"; }
+
+    int client_id() const { return m_client_id; }
+    pid_t client_pid() const { return m_pid; }
+    void set_client_pid(pid_t pid) { m_pid = pid; }
+
+    // ### having this public is sad
+    virtual void send_greeting() = 0;
+
+protected:
+    void event(CEvent& event)
+    {
+        if (event.type() == CIPCServerEvent::ClientDisconnected) {
+            int client_id = static_cast<const ASClientDisconnectedNotification&>(event).client_id();
+            dbgprintf("CIPCServerSideClient: Client disconnected: %d\n", client_id);
+            delete this;
+            return;
+        }
+
+        CObject::event(event);
+    }
+
+    virtual bool handle_message(const ClientMessage&, const ByteBuffer& = {}) = 0;
+
+private:
+    // TODO: A way to create some kind of CIODevice with an open FD would be nice.
+    class COpenedSocket : public CIODevice
+    {
+    public:
+        const char* class_name() const override { return "COpenedSocket"; }
+        COpenedSocket(int fd)
+        {
+            set_fd(fd);
+            set_mode(CIODevice::OpenMode::ReadWrite);
+        }
+
+        bool open(CIODevice::OpenMode) override
+        {
+            ASSERT_NOT_REACHED();
+            return true;
+        };
+
+        int fd() const { return CIODevice::fd(); }
+    };
+
+    COpenedSocket m_socket;
+    CNotifier m_notifier;
+    int m_client_id;
+    int m_pid;
+};
+
+