org.whispersystems.textsecure.internal.push.PushServiceSocket.java Source code

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/**
 * Copyright (C) 2014 Open Whisper Systems
 *
 * 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 org.whispersystems.textsecure.internal.push;

import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.core.JsonProcessingException;

import org.apache.http.conn.ssl.StrictHostnameVerifier;
import org.whispersystems.libaxolotl.IdentityKey;
import org.whispersystems.libaxolotl.ecc.ECPublicKey;
import org.whispersystems.libaxolotl.logging.Log;
import org.whispersystems.libaxolotl.state.PreKeyBundle;
import org.whispersystems.libaxolotl.state.PreKeyRecord;
import org.whispersystems.libaxolotl.state.SignedPreKeyRecord;
import org.whispersystems.libaxolotl.util.guava.Optional;
import org.whispersystems.textsecure.api.crypto.AttachmentCipherOutputStream;
import org.whispersystems.textsecure.api.messages.TextSecureAttachment.ProgressListener;
import org.whispersystems.textsecure.api.messages.multidevice.DeviceInfo;
import org.whispersystems.textsecure.api.push.ContactTokenDetails;
import org.whispersystems.textsecure.api.push.SignedPreKeyEntity;
import org.whispersystems.textsecure.api.push.TextSecureAddress;
import org.whispersystems.textsecure.api.push.TrustStore;
import org.whispersystems.textsecure.api.push.exceptions.AuthorizationFailedException;
import org.whispersystems.textsecure.api.push.exceptions.ExpectationFailedException;
import org.whispersystems.textsecure.api.push.exceptions.NonSuccessfulResponseCodeException;
import org.whispersystems.textsecure.api.push.exceptions.NotFoundException;
import org.whispersystems.textsecure.api.push.exceptions.PushNetworkException;
import org.whispersystems.textsecure.api.push.exceptions.RateLimitException;
import org.whispersystems.textsecure.api.push.exceptions.UnregisteredUserException;
import org.whispersystems.textsecure.api.util.CredentialsProvider;
import org.whispersystems.textsecure.internal.push.exceptions.MismatchedDevicesException;
import org.whispersystems.textsecure.internal.push.exceptions.StaleDevicesException;
import org.whispersystems.textsecure.internal.util.Base64;
import org.whispersystems.textsecure.internal.util.BlacklistingTrustManager;
import org.whispersystems.textsecure.internal.util.JsonUtil;
import org.whispersystems.textsecure.internal.util.Util;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.security.KeyManagementException;
import java.security.NoSuchAlgorithmException;
import java.util.LinkedList;
import java.util.List;
import java.util.Set;

import javax.net.ssl.HttpsURLConnection;
import javax.net.ssl.SSLContext;
import javax.net.ssl.TrustManager;

/**
 *
 * Network interface to the TextSecure server API.
 *
 * @author Moxie Marlinspike
 */
public class PushServiceSocket {

    private static final String TAG = PushServiceSocket.class.getSimpleName();

    private static final String CREATE_ACCOUNT_SMS_PATH = "/v1/accounts/sms/code/%s";
    private static final String CREATE_ACCOUNT_VOICE_PATH = "/v1/accounts/voice/code/%s";
    private static final String VERIFY_ACCOUNT_CODE_PATH = "/v1/accounts/code/%s";
    private static final String VERIFY_ACCOUNT_TOKEN_PATH = "/v1/accounts/token/%s";
    private static final String REGISTER_GCM_PATH = "/v1/accounts/gcm/";
    private static final String REQUEST_TOKEN_PATH = "/v1/accounts/token";
    private static final String SET_ACCOUNT_ATTRIBUTES = "/v1/acccounts/attributes";

    private static final String PREKEY_METADATA_PATH = "/v2/keys/";
    private static final String PREKEY_PATH = "/v2/keys/%s";
    private static final String PREKEY_DEVICE_PATH = "/v2/keys/%s/%s";
    private static final String SIGNED_PREKEY_PATH = "/v2/keys/signed";

    private static final String PROVISIONING_CODE_PATH = "/v1/devices/provisioning/code";
    private static final String PROVISIONING_MESSAGE_PATH = "/v1/provisioning/%s";
    private static final String DEVICE_PATH = "/v1/devices/%s";

    private static final String DIRECTORY_TOKENS_PATH = "/v1/directory/tokens";
    private static final String DIRECTORY_VERIFY_PATH = "/v1/directory/%s";
    private static final String MESSAGE_PATH = "/v1/messages/%s";
    private static final String ACKNOWLEDGE_MESSAGE_PATH = "/v1/messages/%s/%d";
    private static final String RECEIPT_PATH = "/v1/receipt/%s/%d";
    private static final String ATTACHMENT_PATH = "/v1/attachments/%s";

    private static final boolean ENFORCE_SSL = true;

    private final String serviceUrl;
    private final TrustManager[] trustManagers;
    private final CredentialsProvider credentialsProvider;
    private final String userAgent;

    public PushServiceSocket(String serviceUrl, TrustStore trustStore, CredentialsProvider credentialsProvider,
            String userAgent) {
        this.serviceUrl = serviceUrl;
        this.credentialsProvider = credentialsProvider;
        this.trustManagers = BlacklistingTrustManager.createFor(trustStore);
        this.userAgent = userAgent;
    }

    public void createAccount(boolean voice) throws IOException {
        String path = voice ? CREATE_ACCOUNT_VOICE_PATH : CREATE_ACCOUNT_SMS_PATH;
        makeRequest(String.format(path, credentialsProvider.getUser()), "GET", null);
    }

    public void verifyAccountCode(String verificationCode, String signalingKey, int registrationId, boolean voice)
            throws IOException {
        AccountAttributes signalingKeyEntity = new AccountAttributes(signalingKey, registrationId, voice);
        makeRequest(String.format(VERIFY_ACCOUNT_CODE_PATH, verificationCode), "PUT",
                JsonUtil.toJson(signalingKeyEntity));
    }

    public void verifyAccountToken(String verificationToken, String signalingKey, int registrationId, boolean voice)
            throws IOException {
        AccountAttributes signalingKeyEntity = new AccountAttributes(signalingKey, registrationId, voice);
        makeRequest(String.format(VERIFY_ACCOUNT_TOKEN_PATH, verificationToken), "PUT",
                JsonUtil.toJson(signalingKeyEntity));
    }

    public void setAccountAttributes(String signalingKey, int registrationId, boolean voice) throws IOException {
        AccountAttributes accountAttributes = new AccountAttributes(signalingKey, registrationId, voice);
        makeRequest(SET_ACCOUNT_ATTRIBUTES, "PUT", JsonUtil.toJson(accountAttributes));
    }

    public String getAccountVerificationToken() throws IOException {
        String responseText = makeRequest(REQUEST_TOKEN_PATH, "GET", null);
        return JsonUtil.fromJson(responseText, AuthorizationToken.class).getToken();
    }

    public String getNewDeviceVerificationCode() throws IOException {
        String responseText = makeRequest(PROVISIONING_CODE_PATH, "GET", null);
        return JsonUtil.fromJson(responseText, DeviceCode.class).getVerificationCode();
    }

    public List<DeviceInfo> getDevices() throws IOException {
        String responseText = makeRequest(String.format(DEVICE_PATH, ""), "GET", null);
        return JsonUtil.fromJson(responseText, DeviceInfoList.class).getDevices();
    }

    public void removeDevice(long deviceId) throws IOException {
        makeRequest(String.format(DEVICE_PATH, String.valueOf(deviceId)), "DELETE", null);
    }

    public void sendProvisioningMessage(String destination, byte[] body) throws IOException {
        makeRequest(String.format(PROVISIONING_MESSAGE_PATH, destination), "PUT",
                JsonUtil.toJson(new ProvisioningMessage(Base64.encodeBytes(body))));
    }

    public void sendReceipt(String destination, long messageId, Optional<String> relay) throws IOException {
        String path = String.format(RECEIPT_PATH, destination, messageId);

        if (relay.isPresent()) {
            path += "?relay=" + relay.get();
        }

        makeRequest(path, "PUT", null);
    }

    public void registerGcmId(String gcmRegistrationId) throws IOException {
        GcmRegistrationId registration = new GcmRegistrationId(gcmRegistrationId, true);
        makeRequest(REGISTER_GCM_PATH, "PUT", JsonUtil.toJson(registration));
    }

    public void unregisterGcmId() throws IOException {
        makeRequest(REGISTER_GCM_PATH, "DELETE", null);
    }

    public SendMessageResponse sendMessage(OutgoingPushMessageList bundle) throws IOException {
        try {
            String responseText = makeRequest(String.format(MESSAGE_PATH, bundle.getDestination()), "PUT",
                    JsonUtil.toJson(bundle));

            if (responseText == null)
                return new SendMessageResponse(false);
            else
                return JsonUtil.fromJson(responseText, SendMessageResponse.class);
        } catch (NotFoundException nfe) {
            throw new UnregisteredUserException(bundle.getDestination(), nfe);
        }
    }

    public List<TextSecureEnvelopeEntity> getMessages() throws IOException {
        String responseText = makeRequest(String.format(MESSAGE_PATH, ""), "GET", null);
        return JsonUtil.fromJson(responseText, TextSecureEnvelopeEntityList.class).getMessages();
    }

    public void acknowledgeMessage(String sender, long timestamp) throws IOException {
        makeRequest(String.format(ACKNOWLEDGE_MESSAGE_PATH, sender, timestamp), "DELETE", null);
    }

    public void registerPreKeys(IdentityKey identityKey, PreKeyRecord lastResortKey,
            SignedPreKeyRecord signedPreKey, List<PreKeyRecord> records) throws IOException {
        List<PreKeyEntity> entities = new LinkedList<>();

        for (PreKeyRecord record : records) {
            PreKeyEntity entity = new PreKeyEntity(record.getId(), record.getKeyPair().getPublicKey());

            entities.add(entity);
        }

        PreKeyEntity lastResortEntity = new PreKeyEntity(lastResortKey.getId(),
                lastResortKey.getKeyPair().getPublicKey());

        SignedPreKeyEntity signedPreKeyEntity = new SignedPreKeyEntity(signedPreKey.getId(),
                signedPreKey.getKeyPair().getPublicKey(), signedPreKey.getSignature());

        makeRequest(String.format(PREKEY_PATH, ""), "PUT",
                JsonUtil.toJson(new PreKeyState(entities, lastResortEntity, signedPreKeyEntity, identityKey)));
    }

    public int getAvailablePreKeys() throws IOException {
        String responseText = makeRequest(PREKEY_METADATA_PATH, "GET", null);
        PreKeyStatus preKeyStatus = JsonUtil.fromJson(responseText, PreKeyStatus.class);

        return preKeyStatus.getCount();
    }

    public List<PreKeyBundle> getPreKeys(TextSecureAddress destination, int deviceIdInteger) throws IOException {
        try {
            String deviceId = String.valueOf(deviceIdInteger);

            if (deviceId.equals("1"))
                deviceId = "*";

            String path = String.format(PREKEY_DEVICE_PATH, destination.getNumber(), deviceId);

            if (destination.getRelay().isPresent()) {
                path = path + "?relay=" + destination.getRelay().get();
            }

            String responseText = makeRequest(path, "GET", null);
            PreKeyResponse response = JsonUtil.fromJson(responseText, PreKeyResponse.class);
            List<PreKeyBundle> bundles = new LinkedList<>();

            for (PreKeyResponseItem device : response.getDevices()) {
                ECPublicKey preKey = null;
                ECPublicKey signedPreKey = null;
                byte[] signedPreKeySignature = null;
                int preKeyId = -1;
                int signedPreKeyId = -1;

                if (device.getSignedPreKey() != null) {
                    signedPreKey = device.getSignedPreKey().getPublicKey();
                    signedPreKeyId = device.getSignedPreKey().getKeyId();
                    signedPreKeySignature = device.getSignedPreKey().getSignature();
                }

                if (device.getPreKey() != null) {
                    preKeyId = device.getPreKey().getKeyId();
                    preKey = device.getPreKey().getPublicKey();
                }

                bundles.add(new PreKeyBundle(device.getRegistrationId(), device.getDeviceId(), preKeyId, preKey,
                        signedPreKeyId, signedPreKey, signedPreKeySignature, response.getIdentityKey()));
            }

            return bundles;
        } catch (NotFoundException nfe) {
            throw new UnregisteredUserException(destination.getNumber(), nfe);
        }
    }

    public PreKeyBundle getPreKey(TextSecureAddress destination, int deviceId) throws IOException {
        try {
            String path = String.format(PREKEY_DEVICE_PATH, destination.getNumber(), String.valueOf(deviceId));

            if (destination.getRelay().isPresent()) {
                path = path + "?relay=" + destination.getRelay().get();
            }

            String responseText = makeRequest(path, "GET", null);
            PreKeyResponse response = JsonUtil.fromJson(responseText, PreKeyResponse.class);

            if (response.getDevices() == null || response.getDevices().size() < 1)
                throw new IOException("Empty prekey list");

            PreKeyResponseItem device = response.getDevices().get(0);
            ECPublicKey preKey = null;
            ECPublicKey signedPreKey = null;
            byte[] signedPreKeySignature = null;
            int preKeyId = -1;
            int signedPreKeyId = -1;

            if (device.getPreKey() != null) {
                preKeyId = device.getPreKey().getKeyId();
                preKey = device.getPreKey().getPublicKey();
            }

            if (device.getSignedPreKey() != null) {
                signedPreKeyId = device.getSignedPreKey().getKeyId();
                signedPreKey = device.getSignedPreKey().getPublicKey();
                signedPreKeySignature = device.getSignedPreKey().getSignature();
            }

            return new PreKeyBundle(device.getRegistrationId(), device.getDeviceId(), preKeyId, preKey,
                    signedPreKeyId, signedPreKey, signedPreKeySignature, response.getIdentityKey());
        } catch (NotFoundException nfe) {
            throw new UnregisteredUserException(destination.getNumber(), nfe);
        }
    }

    public SignedPreKeyEntity getCurrentSignedPreKey() throws IOException {
        try {
            String responseText = makeRequest(SIGNED_PREKEY_PATH, "GET", null);
            return JsonUtil.fromJson(responseText, SignedPreKeyEntity.class);
        } catch (NotFoundException e) {
            Log.w(TAG, e);
            return null;
        }
    }

    public void setCurrentSignedPreKey(SignedPreKeyRecord signedPreKey) throws IOException {
        SignedPreKeyEntity signedPreKeyEntity = new SignedPreKeyEntity(signedPreKey.getId(),
                signedPreKey.getKeyPair().getPublicKey(), signedPreKey.getSignature());
        makeRequest(SIGNED_PREKEY_PATH, "PUT", JsonUtil.toJson(signedPreKeyEntity));
    }

    public long sendAttachment(PushAttachmentData attachment) throws IOException {
        String response = makeRequest(String.format(ATTACHMENT_PATH, ""), "GET", null);
        AttachmentDescriptor attachmentKey = JsonUtil.fromJson(response, AttachmentDescriptor.class);

        if (attachmentKey == null || attachmentKey.getLocation() == null) {
            throw new IOException("Server failed to allocate an attachment key!");
        }

        Log.w(TAG, "Got attachment content location: " + attachmentKey.getLocation());

        uploadAttachment("PUT", attachmentKey.getLocation(), attachment.getData(), attachment.getDataSize(),
                attachment.getKey(), attachment.getListener());

        return attachmentKey.getId();
    }

    public void retrieveAttachment(String relay, long attachmentId, File destination, ProgressListener listener)
            throws IOException {
        String path = String.format(ATTACHMENT_PATH, String.valueOf(attachmentId));

        if (!Util.isEmpty(relay)) {
            path = path + "?relay=" + relay;
        }

        String response = makeRequest(path, "GET", null);
        AttachmentDescriptor descriptor = JsonUtil.fromJson(response, AttachmentDescriptor.class);

        Log.w(TAG, "Attachment: " + attachmentId + " is at: " + descriptor.getLocation());

        downloadExternalFile(descriptor.getLocation(), destination, listener);
    }

    public List<ContactTokenDetails> retrieveDirectory(Set<String> contactTokens)
            throws NonSuccessfulResponseCodeException, PushNetworkException {
        try {
            ContactTokenList contactTokenList = new ContactTokenList(new LinkedList<>(contactTokens));
            String response = makeRequest(DIRECTORY_TOKENS_PATH, "PUT", JsonUtil.toJson(contactTokenList));
            ContactTokenDetailsList activeTokens = JsonUtil.fromJson(response, ContactTokenDetailsList.class);

            return activeTokens.getContacts();
        } catch (IOException e) {
            Log.w(TAG, e);
            throw new NonSuccessfulResponseCodeException("Unable to parse entity");
        }
    }

    public ContactTokenDetails getContactTokenDetails(String contactToken) throws IOException {
        try {
            String response = makeRequest(String.format(DIRECTORY_VERIFY_PATH, contactToken), "GET", null);
            return JsonUtil.fromJson(response, ContactTokenDetails.class);
        } catch (NotFoundException nfe) {
            return null;
        }
    }

    private void downloadExternalFile(String url, File localDestination, ProgressListener listener)
            throws IOException {
        URL downloadUrl = new URL(url);
        HttpURLConnection connection = (HttpURLConnection) downloadUrl.openConnection();
        connection.setRequestProperty("Content-Type", "application/octet-stream");
        connection.setRequestMethod("GET");
        connection.setDoInput(true);

        try {
            if (connection.getResponseCode() != 200) {
                throw new NonSuccessfulResponseCodeException("Bad response: " + connection.getResponseCode());
            }

            OutputStream output = new FileOutputStream(localDestination);
            InputStream input = connection.getInputStream();
            byte[] buffer = new byte[4096];
            int contentLength = connection.getContentLength();
            int read, totalRead = 0;

            while ((read = input.read(buffer)) != -1) {
                output.write(buffer, 0, read);
                totalRead += read;

                if (listener != null) {
                    listener.onAttachmentProgress(contentLength, totalRead);
                }
            }

            output.close();
            Log.w(TAG, "Downloaded: " + url + " to: " + localDestination.getAbsolutePath());
        } catch (IOException ioe) {
            throw new PushNetworkException(ioe);
        } finally {
            connection.disconnect();
        }
    }

    private void uploadAttachment(String method, String url, InputStream data, long dataSize, byte[] key,
            ProgressListener listener) throws IOException {
        URL uploadUrl = new URL(url);
        HttpsURLConnection connection = (HttpsURLConnection) uploadUrl.openConnection();
        connection.setDoOutput(true);

        if (dataSize > 0) {
            connection
                    .setFixedLengthStreamingMode((int) AttachmentCipherOutputStream.getCiphertextLength(dataSize));
        } else {
            connection.setChunkedStreamingMode(0);
        }

        connection.setRequestMethod(method);
        connection.setRequestProperty("Content-Type", "application/octet-stream");
        connection.setRequestProperty("Connection", "close");
        connection.connect();

        try {
            OutputStream stream = connection.getOutputStream();
            AttachmentCipherOutputStream out = new AttachmentCipherOutputStream(key, stream);
            byte[] buffer = new byte[4096];
            int read, written = 0;

            while ((read = data.read(buffer)) != -1) {
                out.write(buffer, 0, read);
                written += read;

                if (listener != null) {
                    listener.onAttachmentProgress(dataSize, written);
                }
            }

            data.close();
            out.flush();
            out.close();

            if (connection.getResponseCode() != 200) {
                throw new IOException(
                        "Bad response: " + connection.getResponseCode() + " " + connection.getResponseMessage());
            }
        } finally {
            connection.disconnect();
        }
    }

    private String makeRequest(String urlFragment, String method, String body)
            throws NonSuccessfulResponseCodeException, PushNetworkException {
        HttpURLConnection connection = makeBaseRequest(urlFragment, method, body);

        try {
            String response = Util.readFully(connection.getInputStream());
            connection.disconnect();

            return response;
        } catch (IOException ioe) {
            throw new PushNetworkException(ioe);
        }
    }

    private HttpURLConnection makeBaseRequest(String urlFragment, String method, String body)
            throws NonSuccessfulResponseCodeException, PushNetworkException {
        HttpURLConnection connection = getConnection(urlFragment, method, body);
        int responseCode;
        String responseMessage;
        String response;

        try {
            responseCode = connection.getResponseCode();
            responseMessage = connection.getResponseMessage();
        } catch (IOException ioe) {
            throw new PushNetworkException(ioe);
        }

        switch (responseCode) {
        case 413:
            connection.disconnect();
            throw new RateLimitException("Rate limit exceeded: " + responseCode);
        case 401:
        case 403:
            connection.disconnect();
            throw new AuthorizationFailedException("Authorization failed!");
        case 404:
            connection.disconnect();
            throw new NotFoundException("Not found");
        case 409:
            MismatchedDevices mismatchedDevices;

            try {
                response = Util.readFully(connection.getErrorStream());
                mismatchedDevices = JsonUtil.fromJson(response, MismatchedDevices.class);
            } catch (JsonProcessingException e) {
                Log.w(TAG, e);
                throw new NonSuccessfulResponseCodeException(
                        "Bad response: " + responseCode + " " + responseMessage);
            } catch (IOException e) {
                throw new PushNetworkException(e);
            }

            throw new MismatchedDevicesException(mismatchedDevices);
        case 410:
            StaleDevices staleDevices;

            try {
                response = Util.readFully(connection.getErrorStream());
                staleDevices = JsonUtil.fromJson(response, StaleDevices.class);
            } catch (JsonProcessingException e) {
                throw new NonSuccessfulResponseCodeException(
                        "Bad response: " + responseCode + " " + responseMessage);
            } catch (IOException e) {
                throw new PushNetworkException(e);
            }

            throw new StaleDevicesException(staleDevices);
        case 411:
            DeviceLimit deviceLimit;

            try {
                response = Util.readFully(connection.getErrorStream());
                deviceLimit = JsonUtil.fromJson(response, DeviceLimit.class);
            } catch (JsonProcessingException e) {
                throw new NonSuccessfulResponseCodeException(
                        "Bad response: " + responseCode + " " + responseMessage);
            } catch (IOException e) {
                throw new PushNetworkException(e);
            }

            throw new DeviceLimitExceededException(deviceLimit);
        case 417:
            throw new ExpectationFailedException();
        }

        if (responseCode != 200 && responseCode != 204) {
            throw new NonSuccessfulResponseCodeException("Bad response: " + responseCode + " " + responseMessage);
        }

        return connection;
    }

    private HttpURLConnection getConnection(String urlFragment, String method, String body)
            throws PushNetworkException {
        try {
            SSLContext context = SSLContext.getInstance("TLS");
            context.init(null, trustManagers, null);

            URL url = new URL(String.format("%s%s", serviceUrl, urlFragment));
            Log.w(TAG, "Push service URL: " + serviceUrl);
            Log.w(TAG, "Opening URL: " + url);

            HttpURLConnection connection = (HttpURLConnection) url.openConnection();

            if (ENFORCE_SSL) {
                ((HttpsURLConnection) connection).setSSLSocketFactory(context.getSocketFactory());
                ((HttpsURLConnection) connection).setHostnameVerifier(new StrictHostnameVerifier());
            }

            connection.setRequestMethod(method);
            connection.setRequestProperty("Content-Type", "application/json");

            if (credentialsProvider.getPassword() != null) {
                connection.setRequestProperty("Authorization", getAuthorizationHeader());
            }

            if (userAgent != null) {
                connection.setRequestProperty("X-Signal-Agent", userAgent);
            }

            if (body != null) {
                connection.setDoOutput(true);
            }

            connection.connect();

            if (body != null) {
                Log.w(TAG, method + "  --  " + body);
                OutputStream out = connection.getOutputStream();
                out.write(body.getBytes());
                out.close();
            }

            return connection;
        } catch (IOException e) {
            throw new PushNetworkException(e);
        } catch (NoSuchAlgorithmException | KeyManagementException e) {
            throw new AssertionError(e);
        }
    }

    private String getAuthorizationHeader() {
        try {
            return "Basic " + Base64.encodeBytes(
                    (credentialsProvider.getUser() + ":" + credentialsProvider.getPassword()).getBytes("UTF-8"));
        } catch (UnsupportedEncodingException e) {
            throw new AssertionError(e);
        }
    }

    private static class GcmRegistrationId {

        @JsonProperty
        private String gcmRegistrationId;

        @JsonProperty
        private boolean webSocketChannel;

        public GcmRegistrationId() {
        }

        public GcmRegistrationId(String gcmRegistrationId, boolean webSocketChannel) {
            this.gcmRegistrationId = gcmRegistrationId;
            this.webSocketChannel = webSocketChannel;
        }
    }

    private static class AttachmentDescriptor {
        @JsonProperty
        private long id;

        @JsonProperty
        private String location;

        public long getId() {
            return id;
        }

        public String getLocation() {
            return location;
        }
    }
}