AAD & ADAL -- How to verify Authentication code received from AAD?

Hello what is the best practice for verifying that an authentication code returned from Azure Active Directory (via ADAL) is valid/not spoofed/etc.? Right now I don't know how to properly keep a user from invoking  Https://MY_REPLY_URL/ROUTE/CatchCode?code=SOMEGARBAGEAUTHCODEHERE

There must be a more elegant solution than simply:

try{ //if the code is invalid it will throw an exception

var authenticationResult  = authenticationContext.AcquireTokenByAuthorizationCode(authorizationCode, new Uri(AAD.REPLY_URL), clientCredential);

}

catch()

{

// return 401 Forbidden

}

// else use code