add cmake support and fix compile errors

CMakeLists.txt

@@ -0,0 +1,17 @@
+cmake_minimum_required(VERSION 3.7)
+project(udp2raw_tunnel)
+
+set(CMAKE_CXX_STANDARD 11)
+
+set(SOURCE_FILES
+        lib/aes.c
+        lib/md5.c
+        common.cpp
+        encrypt.cpp
+        log.cpp
+        main.cpp
+        network.cpp
+        )
+set(CMAKE_CXX_FLAGS "-Wall -Wextra -Wno-unused-variable -Wno-unused-parameter -static")
+set(CMAKE_LINK_LIBRARY_FLAG "-lrt")
+add_executable(udp2raw_tunnel ${SOURCE_FILES})