LibWebSocket: Add a new websocket library

This library currently contains a basic WebSocket client that can
handle both standard TCP websockets and TLS websockets.

Userland/Libraries/LibWebSocket/Impl/AbstractWebSocketImpl.h

@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2021, The SerenityOS developers.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/ByteBuffer.h>
+#include <AK/Span.h>
+#include <AK/String.h>
+#include <LibCore/Object.h>
+#include <LibWebSocket/ConnectionInfo.h>
+
+namespace WebSocket {
+
+class AbstractWebSocketImpl : public Core::Object {
+    C_OBJECT_ABSTRACT(AbstractWebSocketImpl);
+
+public:
+    virtual ~AbstractWebSocketImpl() override;
+    explicit AbstractWebSocketImpl(Core::Object* parent = nullptr);
+
+    virtual void connect(ConnectionInfo const&) = 0;
+
+    virtual bool can_read_line() = 0;
+    virtual String read_line(size_t size) = 0;
+
+    virtual bool can_read() = 0;
+    virtual ByteBuffer read(int max_size) = 0;
+
+    virtual bool send(ReadonlyBytes) = 0;
+
+    virtual bool eof() = 0;
+
+    virtual void discard_connection() = 0;
+
+    Function<void()> on_connected;
+    Function<void()> on_connection_error;
+    Function<void()> on_ready_to_read;
+};
+
+}