[9750] Add structure of SMSG_REDIRECT_CLIENT (0x50D).

Thanks to TOM_RUS for help with research.

src/game/WorldSocket.h

@@ -42,6 +42,7 @@
 
 #include "Common.h"
 #include "Auth/AuthCrypt.h"
+#include "Auth/BigNumber.h"
 
 class ACE_Message_Block;
 class WorldPacket;
@@ -121,6 +122,9 @@ class WorldSocket : protected WorldHandler
         /// Remove reference to this object.
         long RemoveReference (void);
 
+        /// Return the session key
+        BigNumber& GetSessionKey() { return m_s; }
+
     protected:
         /// things called by ACE framework.
         WorldSocket (void);
@@ -212,6 +216,8 @@ class WorldSocket : protected WorldHandler
         bool m_OutActive;
 
         uint32 m_Seed;
+
+        BigNumber m_s;
 };
 
 #endif  /* _WORLDSOCKET_H */