/// <summary>
/// Ricostruisce le informazioni di accesso al Cloud da una precedente
/// serializzazione
/// </summary>
private void DeSerialize()
{
try
{
Account = null;
string data = File.ReadAllText(SerializationFileName, Encoding.UTF8);
EncDecHelper encDecHelper = new EncDecHelper
{
PasswordString = SerializationPassword
};
Xamarin.Auth.Account account = Xamarin.Auth.Account.Deserialize(encDecHelper.AESDecrypt(data, out bool warning));
if (warning)
{
Debug.Write(string.Format("Google Drive serialize file {0}. File seems to be corrupted. I have tried to recover the data.",
SerializationFileName));
}
if (account != null)
{
Account = new OAuthAccountWrapper(account);
RememberMe = true;
}
}
catch (FileNotFoundException)
{
// Accettabile
Debug.WriteLine(string.Format("Deserialize: file {0} not found", SerializationFileName));
}
catch (Exception Ex)
{
Debug.WriteLine("Deserialize error: " + Ex.Message);
}
}
private void OnOAuth2Completed(object sender, Xamarin.Auth.AuthenticatorCompletedEventArgs e)
{
if (!e.IsAuthenticated)
{
// Non autenticato
Debug.WriteLine("Not authenticated");
LoggedIn?.Invoke(sender, new EventArgs());
return;
}
Account = new OAuthAccountWrapper(e.Account);
Debug.WriteLine("Authenticated");
RememberDataAccess();
LoggedIn?.Invoke(sender, new EventArgs());
}
public async Task <string> RefreshToken(OAuthAccountWrapper account, string clientId, Uri redirectUrl, string appSecret, Uri refreshTokenUrl)
{
if (account.AccessToken.Length == 0)
{
Debug.WriteLine("Token refresh failed!\nUser is not logged in.");
return("");
}
HttpClient appClient = new HttpClient(new Xamarin.Android.Net.AndroidClientHandler());
try
{
List <KeyValuePair <string, string> > Param = new List <KeyValuePair <string, string> >
{
new KeyValuePair <string, string>("client_id", clientId),
new KeyValuePair <string, string>("redirect_uri", redirectUrl.AbsoluteUri),
new KeyValuePair <string, string>("client_secret", appSecret),
new KeyValuePair <string, string>("refresh_token", account.RefreshToken),
new KeyValuePair <string, string>("scope", account.Scope),
new KeyValuePair <string, string>("grant_type", "refresh_token")
};
FormUrlEncodedContent ContentToken = new FormUrlEncodedContent(Param);
HttpResponseMessage ResponseToken = await appClient.PostAsync(refreshTokenUrl, ContentToken);
if (!ResponseToken.IsSuccessStatusCode)
{
appClient.Dispose();
Debug.WriteLine("Token refresh failed: " + ResponseToken.StatusCode);
throw new Exception("Token refresh failed: " + ResponseToken.StatusCode);
}
string content = await ResponseToken.Content.ReadAsStringAsync();
JObject JsonObjToken = JObject.Parse(content);
if (JsonObjToken != null && JsonObjToken.ContainsKey("access_token"))
{
// Aggiorna o inserisce le nuove proprietà
foreach (KeyValuePair <string, JToken> token in JsonObjToken)
{
if (account.OAuthAccount.Properties.ContainsKey(token.Key))
{
account.OAuthAccount.Properties[token.Key] = token.Value.ToString();
}
else
{
account.OAuthAccount.Properties.Add(token.Key, token.Value.ToString());
}
}
if (account.OAuthAccount.Properties.ContainsKey("date_token"))
{
account.OAuthAccount.Properties["date_token"] = DateTime.Now.ToString("dd-MM-yyyy HH:mm:ss");
}
else
{
account.OAuthAccount.Properties.Add("date_token", DateTime.Now.ToString("dd-MM-yyyy HH:mm:ss"));
}
// Ricarica i parametri nel wrapper
account.Refresh();
}
else
{
appClient.Dispose();
Debug.WriteLine("Token refresh failed: malformed response");
throw new Exception("Token refresh failed: malformed response");
}
}
catch (Exception Ex)
{
appClient.Dispose();
Debug.WriteLine("Token refresh failed: " + Ex.Message);
throw new Exception("Token refresh failed: " + Ex.Message);
}
appClient.Dispose();
Debug.WriteLine("Token refreshed!");
return(account.AccessToken);
}
public async void StartAuthentication(string clientId, string scope, string appSecret, Uri authorizeUrl, Uri redirectUrl, Uri tokenUrl, bool codeChallengeMethod)
{
string codeVerifier = "";
UriBuilder uriBuilder = new UriBuilder(authorizeUrl);
uriBuilder.Query += "?client_id=" + clientId + "&scope=" + Uri.EscapeUriString(scope) + "&response_type=code&redirect_uri=" + Uri.EscapeUriString(redirectUrl.AbsoluteUri);
// Codice opzionale di sicurezza
if (codeChallengeMethod)
{
codeVerifier = GetCodeVerifier();
string codeChallenge = Base64URLEncode(EncDecHelper.SHA256Bytes(codeVerifier));
uriBuilder.Query += "&code_challenge_method=S256&code_challenge=" + codeChallenge;
}
try
{
// Step 1: richiede il codice di autorizzazione
WebAuthenticationResult Result = await WebAuthenticationBroker.AuthenticateAsync(WebAuthenticationOptions.None,
uriBuilder.Uri,
redirectUrl);
if (Result.ResponseStatus == WebAuthenticationStatus.Success)
{
Account account = new Account();
// Estraggo il codice
string Code = "";
string QueryString = new Uri(Result.ResponseData).Query;
QueryString = QueryString.Substring(1); // Salta "?"
string[] QueryParams = QueryString.Split('&');
for (short i = 0; i < QueryParams.Length; i++)
{
if (QueryParams[i].Contains("code="))
{
Code = QueryParams[i].Substring(5);
break;
}
}
// Step 2: scambio il codice con un access token
HttpClient appClient = new HttpClient();
try
{
List <KeyValuePair <string, string> > Param = new List <KeyValuePair <string, string> >
{
new KeyValuePair <string, string>("client_id", clientId),
new KeyValuePair <string, string>("redirect_uri", Uri.EscapeUriString(redirectUrl.AbsoluteUri)),
new KeyValuePair <string, string>("code", Uri.EscapeUriString(Code)),
new KeyValuePair <string, string>("scope", scope),
new KeyValuePair <string, string>("grant_type", "authorization_code")
};
// Non è obbligatorio in certi casi (es: Google Drive API per iOS, Android e UWP)
if (appSecret != "")
{
Param.Add(new KeyValuePair <string, string>("client_secret", appSecret));
}
// Codice opzionale di verifica
if (codeChallengeMethod && codeVerifier != "")
{
Param.Add(new KeyValuePair <string, string>("code_verifier", codeVerifier));
}
FormUrlEncodedContent Content = new FormUrlEncodedContent(Param);
HttpResponseMessage Response = await appClient.PostAsync(tokenUrl, Content);
if (Response.IsSuccessStatusCode)
{
// Ottengo un JSON con l'access token, il refesh token e la scadenza.
string content = await Response.Content.ReadAsStringAsync();
JObject JsonObj = JObject.Parse(content);
if (JsonObj != null && JsonObj.ContainsKey("access_token"))
{
foreach (KeyValuePair <string, JToken> token in JsonObj)
{
account.Properties.Add(token.Key, token.Value.ToString());
}
account.Properties.Add("date_token", DateTime.Now.ToString("dd-MM-yyyy HH:mm:ss"));
// Step 3: richiedo un nuovo access token e un refresh token per aggiornare il
// token (in quando voglio accedere offline alla cartella di OneDrive)
OAuthAccountWrapper oAuthAccount = new OAuthAccountWrapper(account);
await RefreshToken(oAuthAccount, clientId, redirectUrl, appSecret, tokenUrl);
if (oAuthAccount.AccessToken.Length <= 0)
{
appClient.Dispose();
Debug.WriteLine("Authetication failed: access token not found in response");
throw new Exception("Access token not found in response");
}
appClient.Dispose();
Debug.WriteLine("Authetication succeeded!");
}
else
{
appClient.Dispose();
Debug.WriteLine("Authetication failed: malformed response");
throw new Exception("Malformed response");
}
}
else
{
appClient.Dispose();
Debug.WriteLine("Authetication failed: " + Response.StatusCode.ToString());
throw new Exception("HTTP Error: " + Response.StatusCode + "\nUnable to redeem a token");
}
AuthenticatorCompletedEventArgs AuthCompletedEventArgs = new AuthenticatorCompletedEventArgs(account);
Completed?.Invoke(this, AuthCompletedEventArgs);
}
catch (Exception Ex)
{
appClient.Dispose();
Debug.WriteLine("Authetication failed: " + Ex.Message);
throw;
}
}
else if (Result.ResponseStatus != WebAuthenticationStatus.UserCancel)
{
Debug.WriteLine("Authetication failed: " + Result.ResponseStatus.ToString());
throw new Exception("HTTP Error code: " + Result.ResponseErrorDetail + "\nError: " + Result.ResponseData);
}
else
{
Debug.WriteLine("Authetication cancelled by user");
// Passando null si avrà IsAuthenticated a false.
// Vedi https://github.com/xamarin/Xamarin.Auth/blob/master/source/Core/Xamarin.Auth.Common.LinkSource/AuthenticatorCompletedEventArgs.cs
AuthenticatorCompletedEventArgs AuthCompletedEventArgs = new AuthenticatorCompletedEventArgs(null);
Completed?.Invoke(this, AuthCompletedEventArgs);
}
}
catch (Exception Ex)
{
Debug.WriteLine("Authetication failed: " + Ex.Message);
AuthenticatorErrorEventArgs AuthCompletedEventArgs = new AuthenticatorErrorEventArgs(Ex);
Error?.Invoke(this, AuthCompletedEventArgs);
}
}
