protocol: add basic communicate protocol pack and unpack.

Protocol/Protocol.h

@@ -0,0 +1,41 @@
+#ifndef PROTOCOL_H
+#define PROTOCOL_H
+
+#include <QByteArray>
+#include <QSharedPointer>
+#include <QString>
+
+// It is specified here that the first 30 contents (inclusive) are
+// used for communication with the server.
+// Contents beyond 30 are only forwarded.
+enum FrameBufferType : uint16_t {
+    FBT_SER_MSG_ASKCLIENTS = 0,
+    FBT_SER_MSG_YOURID,
+    FBT_SER_MSG_RESPONSE,
+    FBT_SER_MSG_FORWARD_FAILED,
+    FBT_CLI_BIN_FILEDATA = 31,
+    FBT_CLI_MSG_COMMUNICATE,
+    FBT_CLI_ASK_DIRFILE,
+    FBT_CLI_ANS_DIRFILE,
+    FBT_CLI_ASK_HOME,
+    FBT_CLI_ANS_HOME
+};
+
+struct FrameBuffer {
+    QByteArray data;
+    QString fid;
+    QString tid;
+    FrameBufferType type;
+};
+
+class Protocol
+{
+public:
+    Protocol();
+
+public:
+    static QSharedPointer<FrameBuffer> ParseBuffer(QByteArray& buffer);
+    static QByteArray PackBuffer(const QSharedPointer<FrameBuffer>& frame);
+};
+
+#endif   // PROTOCOL_H