#8757 new ProviderApiBase includes commonly used code between different implementations of ProviderAPI

1 files changed, 817 insertions, 0 deletions

diff --git a/app/src/main/java/se/leap/bitmaskclient/ProviderApiBase.java b/app/src/main/java/se/leap/bitmaskclient/ProviderApiBase.java
new file mode 100644
index 00000000..caa48231
--- /dev/null
+++ b/app/src/main/java/se/leap/bitmaskclient/ProviderApiBase.java
@@ -0,0 +1,817 @@
+/**
+ * Copyright (c) 2017 LEAP Encryption Access Project and contributers
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+package se.leap.bitmaskclient;
+
+import android.app.IntentService;
+import android.content.Intent;
+import android.content.SharedPreferences;
+import android.content.res.Resources;
+import android.os.Build;
+import android.os.Bundle;
+import android.os.ResultReceiver;
+import android.support.annotation.NonNull;
+import android.util.Base64;
+import android.util.Pair;
+
+import org.json.JSONException;
+import org.json.JSONObject;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.math.BigInteger;
+import java.net.ConnectException;
+import java.net.MalformedURLException;
+import java.net.SocketTimeoutException;
+import java.net.UnknownHostException;
+import java.net.UnknownServiceException;
+import java.security.KeyManagementException;
+import java.security.KeyStoreException;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.security.NoSuchProviderException;
+import java.security.cert.CertificateEncodingException;
+import java.security.cert.CertificateException;
+import java.security.cert.X509Certificate;
+import java.security.interfaces.RSAPrivateKey;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Locale;
+import java.util.Scanner;
+
+import javax.net.ssl.SSLHandshakeException;
+
+import okhttp3.CipherSuite;
+import okhttp3.ConnectionSpec;
+import okhttp3.Cookie;
+import okhttp3.CookieJar;
+import okhttp3.HttpUrl;
+import okhttp3.MediaType;
+import okhttp3.OkHttpClient;
+import okhttp3.Request;
+import okhttp3.RequestBody;
+import okhttp3.Response;
+import okhttp3.TlsVersion;
+import se.leap.bitmaskclient.eip.Constants;
+import se.leap.bitmaskclient.userstatus.SessionDialog;
+import se.leap.bitmaskclient.userstatus.User;
+import se.leap.bitmaskclient.userstatus.UserStatus;
+
+import static se.leap.bitmaskclient.R.string.certificate_error;
+import static se.leap.bitmaskclient.R.string.error_io_exception_user_message;
+import static se.leap.bitmaskclient.R.string.error_json_exception_user_message;
+import static se.leap.bitmaskclient.R.string.error_no_such_algorithm_exception_user_message;
+import static se.leap.bitmaskclient.R.string.keyChainAccessError;
+import static se.leap.bitmaskclient.R.string.malformed_url;
+import static se.leap.bitmaskclient.R.string.server_unreachable_message;
+import static se.leap.bitmaskclient.R.string.service_is_down_error;
+
+/**
+ * Implements HTTP api methods used to manage communications with the provider server.
+ * The implemented methods are commonly used by insecure's and production's flavor of ProviderAPI.
+ * <p/>
+ * It's an IntentService because it downloads data from the Internet, so it operates in the background.
+ *
+ * @author parmegv
+ * @author MeanderingCode
+ * @author cyberta
+ */
+
+public abstract class ProviderApiBase extends IntentService {
+
+    final public static String
+            TAG = ProviderAPI.class.getSimpleName(),
+            SET_UP_PROVIDER = "setUpProvider",
+            DOWNLOAD_NEW_PROVIDER_DOTJSON = "downloadNewProviderDotJSON",
+            SIGN_UP = "srpRegister",
+            LOG_IN = "srpAuth",
+            LOG_OUT = "logOut",
+            DOWNLOAD_CERTIFICATE = "downloadUserAuthedCertificate",
+            PARAMETERS = "parameters",
+            RESULT_KEY = "result",
+            RECEIVER_KEY = "receiver",
+            ERRORS = "errors",
+            UPDATE_PROGRESSBAR = "update_progressbar",
+            CURRENT_PROGRESS = "current_progress",
+            DOWNLOAD_EIP_SERVICE = TAG + ".DOWNLOAD_EIP_SERVICE";
+
+    final public static int
+            SUCCESSFUL_LOGIN = 3,
+            FAILED_LOGIN = 4,
+            SUCCESSFUL_SIGNUP = 5,
+            FAILED_SIGNUP = 6,
+            SUCCESSFUL_LOGOUT = 7,
+            LOGOUT_FAILED = 8,
+            CORRECTLY_DOWNLOADED_CERTIFICATE = 9,
+            INCORRECTLY_DOWNLOADED_CERTIFICATE = 10,
+            PROVIDER_OK = 11,
+            PROVIDER_NOK = 12,
+            CORRECTLY_DOWNLOADED_EIP_SERVICE = 13,
+            INCORRECTLY_DOWNLOADED_EIP_SERVICE = 14;
+
+    public static boolean
+            CA_CERT_DOWNLOADED = false,
+            PROVIDER_JSON_DOWNLOADED = false,
+            EIP_SERVICE_JSON_DOWNLOADED = false;
+
+    protected static String last_provider_main_url;
+    protected static boolean go_ahead = true;
+    protected static SharedPreferences preferences;
+    protected static String provider_api_url;
+    protected static String provider_ca_cert_fingerprint;
+    protected Resources resources;
+
+    public static void stop() {
+        go_ahead = false;
+    }
+
+    private final MediaType JSON
+            = MediaType.parse("application/json; charset=utf-8");
+
+    public ProviderApiBase() {
+        super(TAG);
+    }
+
+    @Override
+    public void onCreate() {
+        super.onCreate();
+
+        preferences = getSharedPreferences(Dashboard.SHARED_PREFERENCES, MODE_PRIVATE);
+        resources = getResources();
+    }
+
+    public static String lastProviderMainUrl() {
+        return last_provider_main_url;
+    }
+
+    @Override
+    protected void onHandleIntent(Intent command) {
+        final ResultReceiver receiver = command.getParcelableExtra(RECEIVER_KEY);
+        String action = command.getAction();
+        Bundle parameters = command.getBundleExtra(PARAMETERS);
+
+        if (provider_api_url == null && preferences.contains(Provider.KEY)) {
+            try {
+                JSONObject provider_json = new JSONObject(preferences.getString(Provider.KEY, ""));
+                provider_api_url = provider_json.getString(Provider.API_URL) + "/" + provider_json.getString(Provider.API_VERSION);
+                go_ahead = true;
+            } catch (JSONException e) {
+                go_ahead = false;
+            }
+        }
+
+        if (action.equalsIgnoreCase(SET_UP_PROVIDER)) {
+            Bundle result = setUpProvider(parameters);
+            if (go_ahead) {
+                if (result.getBoolean(RESULT_KEY)) {
+                    receiver.send(PROVIDER_OK, result);
+                } else {
+                    receiver.send(PROVIDER_NOK, result);
+                }
+            }
+        } else if (action.equalsIgnoreCase(SIGN_UP)) {
+            UserStatus.updateStatus(UserStatus.SessionStatus.SIGNING_UP, resources);
+            Bundle result = tryToRegister(parameters);
+            if (result.getBoolean(RESULT_KEY)) {
+                receiver.send(SUCCESSFUL_SIGNUP, result);
+            } else {
+                receiver.send(FAILED_SIGNUP, result);
+            }
+        } else if (action.equalsIgnoreCase(LOG_IN)) {
+            UserStatus.updateStatus(UserStatus.SessionStatus.LOGGING_IN, resources);
+            Bundle result = tryToAuthenticate(parameters);
+            if (result.getBoolean(RESULT_KEY)) {
+                receiver.send(SUCCESSFUL_LOGIN, result);
+                UserStatus.updateStatus(UserStatus.SessionStatus.LOGGED_IN, resources);
+            } else {
+                receiver.send(FAILED_LOGIN, result);
+                UserStatus.updateStatus(UserStatus.SessionStatus.NOT_LOGGED_IN, resources);
+            }
+        } else if (action.equalsIgnoreCase(LOG_OUT)) {
+            UserStatus.updateStatus(UserStatus.SessionStatus.LOGGING_OUT, resources);
+            if (logOut()) {
+                receiver.send(SUCCESSFUL_LOGOUT, Bundle.EMPTY);
+                UserStatus.updateStatus(UserStatus.SessionStatus.LOGGED_OUT, resources);
+            } else {
+                receiver.send(LOGOUT_FAILED, Bundle.EMPTY);
+                UserStatus.updateStatus(UserStatus.SessionStatus.DIDNT_LOG_OUT, resources);
+            }
+        } else if (action.equalsIgnoreCase(DOWNLOAD_CERTIFICATE)) {
+            if (updateVpnCertificate()) {
+                receiver.send(CORRECTLY_DOWNLOADED_CERTIFICATE, Bundle.EMPTY);
+            } else {
+                receiver.send(INCORRECTLY_DOWNLOADED_CERTIFICATE, Bundle.EMPTY);
+            }
+        } else if (action.equalsIgnoreCase(DOWNLOAD_EIP_SERVICE)) {
+            Bundle result = getAndSetEipServiceJson();
+            if (result.getBoolean(RESULT_KEY)) {
+                receiver.send(CORRECTLY_DOWNLOADED_EIP_SERVICE, result);
+            } else {
+                receiver.send(INCORRECTLY_DOWNLOADED_EIP_SERVICE, result);
+            }
+        }
+    }
+
+    protected String formatErrorMessage(final int toastStringId) {
+        return formatErrorMessage(getResources().getString(toastStringId));
+    }
+
+    private String formatErrorMessage(String errorMessage) {
+        return "{ \"" + ERRORS + "\" : \"" + errorMessage + "\" }";
+    }
+
+    private JSONObject getErrorMessageAsJson(final int toastStringId) {
+        try {
+            return new JSONObject(formatErrorMessage(toastStringId));
+        } catch (JSONException e) {
+            e.printStackTrace();
+            return new JSONObject();
+        }
+    }
+
+    private JSONObject getErrorMessageAsJson(String message) {
+        try {
+            return new JSONObject(formatErrorMessage(message));
+        } catch (JSONException e) {
+            e.printStackTrace();
+            return new JSONObject();
+        }
+    }
+    private OkHttpClient initHttpClient(JSONObject initError, boolean isSelfSigned) {
+        try {
+            TLSCompatSocketFactory sslCompatFactory;
+            ConnectionSpec spec = getConnectionSpec();
+            OkHttpClient.Builder clientBuilder = new OkHttpClient.Builder();
+            if (isSelfSigned) {
+                sslCompatFactory = new TLSCompatSocketFactory(preferences.getString(Provider.CA_CERT, ""));
+
+            } else {
+                sslCompatFactory = new TLSCompatSocketFactory();
+            }
+            sslCompatFactory.initSSLSocketFactory(clientBuilder);
+            clientBuilder.cookieJar(getCookieJar())
+                    .connectionSpecs(Collections.singletonList(spec));
+            return clientBuilder.build();
+        } catch (IllegalStateException e) {
+            e.printStackTrace();
+            initError = getErrorMessageAsJson(String.format(resources.getString(keyChainAccessError), e.getLocalizedMessage()));
+        } catch (KeyStoreException e) {
+            e.printStackTrace();
+            initError = getErrorMessageAsJson(String.format(resources.getString(keyChainAccessError), e.getLocalizedMessage()));
+        } catch (KeyManagementException e) {
+            e.printStackTrace();
+            initError = getErrorMessageAsJson(String.format(resources.getString(keyChainAccessError), e.getLocalizedMessage()));
+        } catch (NoSuchAlgorithmException e) {
+            e.printStackTrace();
+            initError = getErrorMessageAsJson(resources.getString(error_no_such_algorithm_exception_user_message));
+        } catch (CertificateException e) {
+            e.printStackTrace();
+            initError = getErrorMessageAsJson(resources.getString(certificate_error));
+        } catch (UnknownHostException e) {
+            e.printStackTrace();
+            initError = getErrorMessageAsJson(resources.getString(server_unreachable_message));
+        } catch (IOException e) {
+            e.printStackTrace();
+            initError = getErrorMessageAsJson(resources.getString(error_io_exception_user_message));
+        } catch (NoSuchProviderException e) {
+            e.printStackTrace();
+            initError = getErrorMessageAsJson(resources.getString(error_no_such_algorithm_exception_user_message));
+        }
+        return null;
+    }
+
+    protected OkHttpClient initCommercialCAHttpClient(JSONObject initError) {
+        return initHttpClient(initError, false);
+    }
+
+    protected OkHttpClient initSelfSignedCAHttpClient(JSONObject initError) {
+        return initHttpClient(initError, true);
+    }
+
+    @NonNull
+    private ConnectionSpec getConnectionSpec() {
+        ConnectionSpec.Builder connectionSpecbuilder = new ConnectionSpec.Builder(ConnectionSpec.MODERN_TLS)
+                .tlsVersions(TlsVersion.TLS_1_2, TlsVersion.TLS_1_3);
+        //FIXME: restrict connection further to the following recommended cipher suites for ALL supported API levels
+        //figure out how to use bcjsse for that purpose
+        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP_MR1)
+            connectionSpecbuilder.cipherSuites(
+                    CipherSuite.TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256,
+                    CipherSuite.TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256,
+                    CipherSuite.TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384,
+                    CipherSuite.TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384,
+                    CipherSuite.TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256,
+                    CipherSuite.TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256
+            );
+        return connectionSpecbuilder.build();
+    }
+
+    @NonNull
+    private CookieJar getCookieJar() {
+        return new CookieJar() {
+            private final HashMap<String, List<Cookie>> cookieStore = new HashMap<>();
+
+            @Override
+            public void saveFromResponse(HttpUrl url, List<Cookie> cookies) {
+                cookieStore.put(url.host(), cookies);
+            }
+
+            @Override
+            public List<Cookie> loadForRequest(HttpUrl url) {
+                List<Cookie> cookies = cookieStore.get(url.host());
+                return cookies != null ? cookies : new ArrayList<Cookie>();
+            }
+        };
+    }
+
+
+    private Bundle tryToRegister(Bundle task) {
+        Bundle result = new Bundle();
+        int progress = 0;
+
+        String username = User.userName();
+        String password = task.getString(SessionDialog.PASSWORD);
+
+        if (validUserLoginData(username, password)) {
+            result = register(username, password);
+            broadcastProgress(progress++);
+        } else {
+            if (!wellFormedPassword(password)) {
+                result.putBoolean(RESULT_KEY, false);
+                result.putString(SessionDialog.USERNAME, username);
+                result.putBoolean(SessionDialog.ERRORS.PASSWORD_INVALID_LENGTH.toString(), true);
+            }
+            if (!validUsername(username)) {
+                result.putBoolean(RESULT_KEY, false);
+                result.putBoolean(SessionDialog.ERRORS.USERNAME_MISSING.toString(), true);
+            }
+        }
+
+        return result;
+    }
+
+    private Bundle register(String username, String password) {
+        JSONObject stepResult = null;
+        OkHttpClient okHttpClient = initSelfSignedCAHttpClient(stepResult);
+        if (okHttpClient == null) {
+            return authFailedNotification(stepResult, username);
+        }
+
+        LeapSRPSession client = new LeapSRPSession(username, password);
+        byte[] salt = client.calculateNewSalt();
+
+        BigInteger password_verifier = client.calculateV(username, password, salt);
+
+        JSONObject api_result = sendNewUserDataToSRPServer(provider_api_url, username, new BigInteger(1, salt).toString(16), password_verifier.toString(16), okHttpClient);
+
+        Bundle result = new Bundle();
+        if (api_result.has(ERRORS))
+            result = authFailedNotification(api_result, username);
+        else {
+            result.putString(SessionDialog.USERNAME, username);
+            result.putString(SessionDialog.PASSWORD, password);
+            result.putBoolean(RESULT_KEY, true);
+        }
+
+        return result;
+    }
+
+    /**
+     * Starts the authentication process using SRP protocol.
+     *
+     * @param task containing: username, password and api url.
+     * @return a bundle with a boolean value mapped to a key named RESULT_KEY, and which is true if authentication was successful.
+     */
+    private Bundle tryToAuthenticate(Bundle task) {
+        Bundle result = new Bundle();
+        int progress = 0;
+
+        String username = User.userName();
+        String password = task.getString(SessionDialog.PASSWORD);
+        if (validUserLoginData(username, password)) {
+            result = authenticate(username, password);
+            broadcastProgress(progress++);
+        } else {
+            if (!wellFormedPassword(password)) {
+                result.putBoolean(RESULT_KEY, false);
+                result.putString(SessionDialog.USERNAME, username);
+                result.putBoolean(SessionDialog.ERRORS.PASSWORD_INVALID_LENGTH.toString(), true);
+            }
+            if (!validUsername(username)) {
+                result.putBoolean(RESULT_KEY, false);
+                result.putBoolean(SessionDialog.ERRORS.USERNAME_MISSING.toString(), true);
+            }
+        }
+
+        return result;
+    }
+
+    private Bundle authenticate(String username, String password) {
+        Bundle result = new Bundle();
+        JSONObject stepResult = new JSONObject();
+        OkHttpClient okHttpClient = initSelfSignedCAHttpClient(stepResult);
+        if (okHttpClient == null) {
+            return authFailedNotification(stepResult, username);
+        }
+
+        LeapSRPSession client = new LeapSRPSession(username, password);
+        byte[] A = client.exponential();
+
+        JSONObject step_result = sendAToSRPServer(provider_api_url, username, new BigInteger(1, A).toString(16), okHttpClient);
+        try {
+            String salt = step_result.getString(LeapSRPSession.SALT);
+            byte[] Bbytes = new BigInteger(step_result.getString("B"), 16).toByteArray();
+            byte[] M1 = client.response(new BigInteger(salt, 16).toByteArray(), Bbytes);
+            if (M1 != null) {
+                step_result = sendM1ToSRPServer(provider_api_url, username, M1, okHttpClient);
+                setTokenIfAvailable(step_result);
+                byte[] M2 = new BigInteger(step_result.getString(LeapSRPSession.M2), 16).toByteArray();
+                if (client.verify(M2)) {
+                    result.putBoolean(RESULT_KEY, true);
+                } else {
+                    authFailedNotification(step_result, username);
+                }
+            } else {
+                result.putBoolean(RESULT_KEY, false);
+                result.putString(SessionDialog.USERNAME, username);
+                result.putString(resources.getString(R.string.user_message), resources.getString(R.string.error_srp_math_error_user_message));
+            }
+        } catch (JSONException e) {
+            result = authFailedNotification(step_result, username);
+            e.printStackTrace();
+        }
+
+        return result;
+    }
+
+    private boolean setTokenIfAvailable(JSONObject authentication_step_result) {
+        try {
+            LeapSRPSession.setToken(authentication_step_result.getString(LeapSRPSession.TOKEN));
+        } catch (JSONException e) { //
+            return false;
+        }
+        return true;
+    }
+
+    private Bundle authFailedNotification(JSONObject result, String username) {
+        Bundle userNotificationBundle = new Bundle();
+        Object baseErrorMessage = result.opt(ERRORS);
+        if (baseErrorMessage != null) {
+            if (baseErrorMessage instanceof JSONObject) {
+                try {
+                    JSONObject errorMessage = result.getJSONObject(ERRORS);
+                    String errorType = errorMessage.keys().next().toString();
+                    String message = errorMessage.get(errorType).toString();
+                    userNotificationBundle.putString(resources.getString(R.string.user_message), message);
+                } catch (JSONException e) {
+                    e.printStackTrace();
+                }
+            } else if (baseErrorMessage instanceof String) {
+                try {
+                    String errorMessage = result.getString(ERRORS);
+                    userNotificationBundle.putString(resources.getString(R.string.user_message), errorMessage);
+                } catch (JSONException e) {
+                    e.printStackTrace();
+                }
+            }
+        }
+
+        if (!username.isEmpty())
+            userNotificationBundle.putString(SessionDialog.USERNAME, username);
+        userNotificationBundle.putBoolean(RESULT_KEY, false);
+
+        return userNotificationBundle;
+    }
+
+    /**
+     * Sets up an intent with the progress value passed as a parameter
+     * and sends it as a broadcast.
+     *
+     * @param progress
+     */
+    protected void broadcastProgress(int progress) {
+        Intent intentUpdate = new Intent();
+        intentUpdate.setAction(UPDATE_PROGRESSBAR);
+        intentUpdate.addCategory(Intent.CATEGORY_DEFAULT);
+        intentUpdate.putExtra(CURRENT_PROGRESS, progress);
+        sendBroadcast(intentUpdate);
+    }
+
+    /**
+     * Validates parameters entered by the user to log in
+     *
+     * @param username
+     * @param password
+     * @return true if both parameters are present and the entered password length is greater or equal to eight (8).
+     */
+    private boolean validUserLoginData(String username, String password) {
+        return validUsername(username) && wellFormedPassword(password);
+    }
+
+    private boolean validUsername(String username) {
+        return username != null && !username.isEmpty();
+    }
+
+    /**
+     * Validates a password
+     *
+     * @param password
+     * @return true if the entered password length is greater or equal to eight (8).
+     */
+    private boolean wellFormedPassword(String password) {
+        return password != null && password.length() >= 8;
+    }
+
+    /**
+     * Sends an HTTP POST request to the authentication server with the SRP Parameter A.
+     *
+     * @param server_url
+     * @param username
+     * @param clientA    First SRP parameter sent
+     * @param okHttpClient
+     * @return response from authentication server
+     */
+    private JSONObject sendAToSRPServer(String server_url, String username, String clientA, OkHttpClient okHttpClient) {
+        SrpCredentials srpCredentials = new SrpCredentials(username, clientA);
+        return sendToServer(server_url + "/sessions.json", "POST", srpCredentials.toString(), okHttpClient);
+    }
+
+    /**
+     * Sends an HTTP PUT request to the authentication server with the SRP Parameter M1 (or simply M).
+     *
+     * @param server_url
+     * @param username
+     * @param m1         Second SRP parameter sent
+     * @param okHttpClient
+     * @return response from authentication server
+     */
+    private JSONObject sendM1ToSRPServer(String server_url, String username, byte[] m1, OkHttpClient okHttpClient) {
+        String m1json = "{\"client_auth\":\"" + new BigInteger(1, ConfigHelper.trim(m1)).toString(16)+ "\"}";
+        return sendToServer(server_url + "/sessions/" + username + ".json", "PUT", m1json, okHttpClient);
+    }
+
+    /**
+     * Sends an HTTP POST request to the api server to register a new user.
+     *
+     * @param server_url
+     * @param username
+     * @param salt
+     * @param password_verifier
+     * @param okHttpClient
+     * @return response from authentication server
+     */
+    private JSONObject sendNewUserDataToSRPServer(String server_url, String username, String salt, String password_verifier, OkHttpClient okHttpClient) {
+        return sendToServer(server_url + "/users.json", "POST", new SrpRegistrationData(username, salt, password_verifier).toString(), okHttpClient);
+    }
+
+    /**
+     * Executes an HTTP request expecting a JSON response.
+     *
+     * @param url
+     * @param request_method
+     * @return response from authentication server
+     */
+    private JSONObject sendToServer(String url, String request_method, String jsonString, OkHttpClient okHttpClient) {
+        return requestJsonFromServer(url, request_method, jsonString, null, okHttpClient);
+    }
+
+    protected String sendGetStringToServer(String url, List<Pair<String, String>> headerArgs, OkHttpClient okHttpClient) {
+        return requestStringFromServer(url, "GET", null, headerArgs, okHttpClient);
+    }
+
+
+
+    private JSONObject requestJsonFromServer(String url, String request_method, String jsonString, List<Pair<String, String>> headerArgs, @NonNull OkHttpClient okHttpClient)  {
+        JSONObject responseJson;
+        String plain_response = requestStringFromServer(url, request_method, jsonString, headerArgs, okHttpClient);
+
+        try {
+            responseJson = new JSONObject(plain_response);
+        } catch (JSONException e) {
+            e.printStackTrace();
+            responseJson = getErrorMessageAsJson(error_json_exception_user_message);
+        }
+        return responseJson;
+
+    }
+
+    private String requestStringFromServer(String url, String request_method, String jsonString, List<Pair<String, String>> headerArgs, @NonNull OkHttpClient okHttpClient) {
+        Response response;
+        String plainResponseBody = null;
+
+        RequestBody jsonBody = jsonString != null ? RequestBody.create(JSON, jsonString) : null;
+        Request.Builder requestBuilder = new Request.Builder()
+                .url(url)
+                .method(request_method, jsonBody);
+        if (headerArgs != null) {
+            for (Pair<String, String> keyValPair : headerArgs) {
+                requestBuilder.addHeader(keyValPair.first, keyValPair.second);
+            }
+        }
+        //TODO: move to getHeaderArgs()?
+        String locale = Locale.getDefault().getLanguage() + Locale.getDefault().getCountry();
+        requestBuilder.addHeader("Accept-Language", locale);
+        Request request = requestBuilder.build();
+
+        try {
+            response = okHttpClient.newCall(request).execute();
+
+            InputStream inputStream = response.body().byteStream();
+            Scanner scanner = new Scanner(inputStream).useDelimiter("\\A");
+            if (scanner.hasNext()) {
+                plainResponseBody = scanner.next();
+            }
+
+        } catch (NullPointerException npe) {
+            plainResponseBody = formatErrorMessage(error_json_exception_user_message);
+        } catch (UnknownHostException e) {
+            plainResponseBody = formatErrorMessage(server_unreachable_message);
+        } catch (MalformedURLException e) {
+            plainResponseBody = formatErrorMessage(malformed_url);
+        } catch (SocketTimeoutException e) {
+            plainResponseBody = formatErrorMessage(server_unreachable_message);
+        } catch (SSLHandshakeException e) {
+            plainResponseBody = formatErrorMessage(certificate_error);
+        } catch (ConnectException e) {
+            plainResponseBody = formatErrorMessage(service_is_down_error);
+        } catch (IllegalArgumentException e) {
+            plainResponseBody = formatErrorMessage(error_no_such_algorithm_exception_user_message);
+        } catch (UnknownServiceException e) {
+            //unable to find acceptable protocols - tlsv1.2 not enabled?
+            plainResponseBody = formatErrorMessage(error_no_such_algorithm_exception_user_message);
+        } catch (IOException e) {
+            plainResponseBody = formatErrorMessage(error_io_exception_user_message);
+        }
+
+        return plainResponseBody;
+    }
+
+    /**
+     * Downloads a provider.json from a given URL, adding a new provider using the given name.
+     *
+     * @param task containing a boolean meaning if the provider is custom or not, another boolean meaning if the user completely trusts this provider, the provider name and its provider.json url.
+     * @return a bundle with a boolean value mapped to a key named RESULT_KEY, and which is true if the update was successful.
+     */
+    protected abstract Bundle setUpProvider(Bundle task);
+
+    /**
+     * Downloads the eip-service.json from a given URL, and saves eip service capabilities including the offered gateways
+     * @return a bundle with a boolean value mapped to a key named RESULT_KEY, and which is true if the download was successful.
+     */
+    protected abstract Bundle getAndSetEipServiceJson();
+
+    /**
+     * Downloads a new OpenVPN certificate, attaching authenticated cookie for authenticated certificate.
+     *
+     * @return true if certificate was downloaded correctly, false if provider.json is not present in SharedPreferences, or if the certificate url could not be parsed as a URI, or if there was an SSL error.
+     */
+    protected abstract boolean updateVpnCertificate();
+
+
+    protected static boolean caCertDownloaded() {
+        return CA_CERT_DOWNLOADED;
+    }
+
+    protected boolean validCertificate(String cert_string) {
+        boolean result = false;
+        if (!ConfigHelper.checkErroneousDownload(cert_string)) {
+            X509Certificate certificate = ConfigHelper.parseX509CertificateFromString(cert_string);
+            try {
+                if (certificate != null) {
+                    JSONObject provider_json = new JSONObject(preferences.getString(Provider.KEY, ""));
+                    String fingerprint = provider_json.getString(Provider.CA_CERT_FINGERPRINT);
+                    String encoding = fingerprint.split(":")[0];
+                    String expected_fingerprint = fingerprint.split(":")[1];
+                    String real_fingerprint = base64toHex(Base64.encodeToString(
+                            MessageDigest.getInstance(encoding).digest(certificate.getEncoded()),
+                            Base64.DEFAULT));
+
+                    result = real_fingerprint.trim().equalsIgnoreCase(expected_fingerprint.trim());
+                } else
+                    result = false;
+            } catch (JSONException e) {
+                result = false;
+            } catch (NoSuchAlgorithmException e) {
+                result = false;
+            } catch (CertificateEncodingException e) {
+                result = false;
+            }
+        }
+
+        return result;
+    }
+
+    private String base64toHex(String base64_input) {
+        byte[] byteArray = Base64.decode(base64_input, Base64.DEFAULT);
+        int readBytes = byteArray.length;
+        StringBuffer hexData = new StringBuffer();
+        int onebyte;
+        for (int i = 0; i < readBytes; i++) {
+            onebyte = ((0x000000ff & byteArray[i]) | 0xffffff00);
+            hexData.append(Integer.toHexString(onebyte).substring(6));
+        }
+        return hexData.toString();
+    }
+
+    /**
+     * Interprets the error message as a JSON object and extract the "errors" keyword pair.
+     * If the error message is not a JSON object, then it is returned untouched.
+     *
+     * @param string_json_error_message
+     * @return final error message
+     */
+    protected String pickErrorMessage(String string_json_error_message) {
+        String error_message = "";
+        try {
+            JSONObject json_error_message = new JSONObject(string_json_error_message);
+            error_message = json_error_message.getString(ERRORS);
+        } catch (JSONException e) {
+            // TODO Auto-generated catch block
+            error_message = string_json_error_message;
+        }
+
+        return error_message;
+    }
+
+    @NonNull
+    protected List<Pair<String, String>> getAuthorizationHeader() {
+        List<Pair<String, String>> headerArgs = new ArrayList<>();
+        if (!LeapSRPSession.getToken().isEmpty()) {
+            Pair<String, String> authorizationHeaderPair = new Pair<>(LeapSRPSession.AUTHORIZATION_HEADER, "Token token=" + LeapSRPSession.getToken());
+            headerArgs.add(authorizationHeaderPair);
+        }
+        return headerArgs;
+    }
+
+    private boolean logOut() {
+        OkHttpClient okHttpClient = initSelfSignedCAHttpClient(new JSONObject());
+        if (okHttpClient == null) {
+            return false;
+        }
+
+        String deleteUrl = provider_api_url + "/logout";
+        int progress = 0;
+
+        Request.Builder requestBuilder = new Request.Builder()
+                .url(deleteUrl)
+                .delete();
+        Request request = requestBuilder.build();
+
+        try {
+            Response response = okHttpClient.newCall(request).execute();
+                                            // v---- was already not authorized
+            if (response.isSuccessful() || response.code() == 401) {
+                broadcastProgress(progress++);
+                LeapSRPSession.setToken("");
+            }
+
+        } catch (IOException e) {
+            return false;
+        }
+        return true;
+    }
+
+    //FIXME: don't save private keys in shared preferences! use the keystore
+    protected boolean loadCertificate(String cert_string) {
+        try {
+            // API returns concatenated cert & key.  Split them for OpenVPN options
+            String certificateString = null, keyString = null;
+            String[] certAndKey = cert_string.split("(?<=-\n)");
+            for (int i = 0; i < certAndKey.length - 1; i++) {
+                if (certAndKey[i].contains("KEY")) {
+                    keyString = certAndKey[i++] + certAndKey[i];
+                } else if (certAndKey[i].contains("CERTIFICATE")) {
+                    certificateString = certAndKey[i++] + certAndKey[i];
+                }
+            }
+
+            RSAPrivateKey key = ConfigHelper.parseRsaKeyFromString(keyString);
+            keyString = Base64.encodeToString(key.getEncoded(), Base64.DEFAULT);
+            preferences.edit().putString(Constants.PRIVATE_KEY, "-----BEGIN RSA PRIVATE KEY-----\n" + keyString + "-----END RSA PRIVATE KEY-----").commit();
+
+            X509Certificate certificate = ConfigHelper.parseX509CertificateFromString(certificateString);
+            certificateString = Base64.encodeToString(certificate.getEncoded(), Base64.DEFAULT);
+            preferences.edit().putString(Constants.VPN_CERTIFICATE, "-----BEGIN CERTIFICATE-----\n" + certificateString + "-----END CERTIFICATE-----").commit();
+            return true;
+        } catch (CertificateException e) {
+            // TODO Auto-generated catch block
+            e.printStackTrace();
+            return false;
+        }
+    }
+}