Clang function cursor return type

I am trying to get the type of parameters and type of return of a C function.

For example I have function:

int addTwoIntegers(int a, int b){
        return a + b;
}

What I need is: int (int, int)

I am using clang frontend to generate AST. Currently I have:

CXString cursorVariables = clang_getCursorDisplayName( cursor );
string methodDecl      = clang_getCString( cursorVariables );
cout << methodDecl << '\n';

It gives me:

addTwoIntegers(int, int)

and nothing about the type of the return value. My question is how should I get the return type of function from cursor CXCursor_FunctionDecl?