src/com/android/telecomm/PhoneAccountRegistrar.java

/*
 * Copyright (C) 2014 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.telecomm;

import android.telecomm.PhoneAccount;
import android.telecomm.PhoneAccountHandle;
import android.content.ComponentName;
import android.content.Context;
import android.net.Uri;
import android.telecomm.TelecommManager;
import android.util.AtomicFile;
import android.util.Xml;

import com.android.internal.annotations.VisibleForTesting;
import com.android.internal.util.FastXmlSerializer;
import com.android.internal.util.XmlUtils;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Objects;
import java.util.concurrent.CopyOnWriteArrayList;

import org.xmlpull.v1.XmlPullParser;
import org.xmlpull.v1.XmlPullParserException;
import org.xmlpull.v1.XmlSerializer;

/**
 * Handles writing and reading PhoneAccountHandle registration entries. This is a simple verbatim
 * delegate for all the account handling methods on {@link TelecommManager} as implemented in
 * {@link TelecommServiceImpl}, with the notable exception that {@link TelecommServiceImpl} is
 * responsible for security checking to make sure that the caller has proper authority over
 * the {@code ComponentName}s they are declaring in their {@code PhoneAccountHandle}s.
 */
public final class PhoneAccountRegistrar {

    public abstract static class Listener {
        public void onAccountsChanged(PhoneAccountRegistrar registrar) {}
        public void onDefaultOutgoingChanged(PhoneAccountRegistrar registrar) {}
        public void onSimCallManagerChanged(PhoneAccountRegistrar registrar) {}
    }

    private static final String FILE_NAME = "phone-account-registrar-state.xml";

    private final List<Listener> mListeners = new CopyOnWriteArrayList<>();
    private final AtomicFile mAtomicFile;
    private State mState;

    public PhoneAccountRegistrar(Context context) {
        this(context, FILE_NAME);
    }

    @VisibleForTesting
    public PhoneAccountRegistrar(Context context, String fileName) {
        // TODO: Change file location when Telecomm is part of system
        mAtomicFile = new AtomicFile(new File(context.getFilesDir(), fileName));
        mState = new State();
        read();
    }

    public PhoneAccountHandle getDefaultOutgoingPhoneAccount() {
        if (mState.defaultOutgoing != null) {
            // Return the registered outgoing default iff it still exists (we keep a sticky
            // default to survive account deletion and re-addition)
            for (int i = 0; i < mState.accounts.size(); i++) {
                if (mState.accounts.get(i).getAccountHandle().equals(mState.defaultOutgoing)) {
                    return mState.defaultOutgoing;
                }
            }
            // At this point, there was a registered default but it has been deleted; proceed
            // as though there were no default
        }

        List<PhoneAccountHandle> enabled = getEnabledPhoneAccounts();
        switch (enabled.size()) {
            case 0:
                // There are no accounts, so there can be no default
                return null;
            case 1:
                // There is only one account, which is by definition the default
                return enabled.get(0);
            default:
                // There are multiple accounts with no selected default
                return null;
        }
    }

    public void setDefaultOutgoingPhoneAccount(PhoneAccountHandle accountHandle) {
        if (accountHandle == null) {
            // Asking to clear the default outgoing is a valid request
            mState.defaultOutgoing = null;
        } else {
            boolean found = false;
            for (PhoneAccount m : mState.accounts) {
                if (Objects.equals(accountHandle, m.getAccountHandle())) {
                    found = true;
                    break;
                }
            }

            if (!found) {
                Log.w(this, "Trying to set nonexistent default outgoing %s",
                        accountHandle);
                return;
            }

            if (!has(getPhoneAccount(accountHandle), PhoneAccount.CAPABILITY_CALL_PROVIDER)) {
                Log.w(this, "Trying to set non-call-provider default outgoing %s",
                        accountHandle);
                return;
            }

            mState.defaultOutgoing = accountHandle;
        }

        write();
        fireDefaultOutgoingChanged();
    }

    public void setSimCallManager(PhoneAccountHandle callManager) {
        if (callManager != null) {
            PhoneAccount callManagerAccount = getPhoneAccount(callManager);
            if (callManagerAccount == null) {
                Log.d(this, "setSimCallManager: Nonexistent call manager: %s", callManager);
                return;
            } else if (!has(callManagerAccount, PhoneAccount.CAPABILITY_CONNECTION_MANAGER)) {
                Log.d(this, "setSimCallManager: Not a call manager: %s", callManagerAccount);
                return;
            }
        }
        mState.simCallManager = callManager;
        write();
        fireSimCallManagerChanged();
    }

    public PhoneAccountHandle getSimCallManager() {
        if (mState.simCallManager != null) {
            // Return the registered sim call manager iff it still exists (we keep a sticky
            // setting to survive account deletion and re-addition)
            for (int i = 0; i < mState.accounts.size(); i++) {
                if (mState.accounts.get(i).getAccountHandle().equals(mState.simCallManager)) {
                    return mState.simCallManager;
                }
            }
        }
        return null;
    }

    public List<PhoneAccountHandle> getAllPhoneAccountHandles() {
        List<PhoneAccountHandle> accountHandles = new ArrayList<>();
        for (PhoneAccount m : mState.accounts) {
            accountHandles.add(m.getAccountHandle());
        }
        return accountHandles;
    }

    public List<PhoneAccount> getAllPhoneAccounts() {
        return new ArrayList<>(mState.accounts);
    }

    // TODO: Rename systemwide to "getCallProviderPhoneAccounts"?
    public List<PhoneAccountHandle> getEnabledPhoneAccounts() {
        return getCallProviderAccountHandles();
    }

    public PhoneAccount getPhoneAccount(PhoneAccountHandle handle) {
        for (PhoneAccount m : mState.accounts) {
            if (Objects.equals(handle, m.getAccountHandle())) {
                return m;
            }
        }
        return null;
    }

    // TODO: Should we implement an artificial limit for # of accounts associated with a single
    // ComponentName?
    public void registerPhoneAccount(PhoneAccount account) {
        mState.accounts.add(account);
        // Search for duplicates and remove any that are found.
        for (int i = 0; i < mState.accounts.size() - 1; i++) {
            if (Objects.equals(
                    account.getAccountHandle(), mState.accounts.get(i).getAccountHandle())) {
                // replace existing entry.
                mState.accounts.remove(i);
                break;
            }
        }

        write();
        fireAccountsChanged();
    }

    public void unregisterPhoneAccount(PhoneAccountHandle accountHandle) {
        for (int i = 0; i < mState.accounts.size(); i++) {
            if (Objects.equals(accountHandle, mState.accounts.get(i).getAccountHandle())) {
                mState.accounts.remove(i);
                break;
            }
        }

        write();
        fireAccountsChanged();
    }

    public void clearAccounts(String packageName) {
        for (int i = 0; i < mState.accounts.size(); i++) {
            if (Objects.equals(
                    packageName,
                    mState.accounts.get(i).getAccountHandle()
                            .getComponentName().getPackageName())) {
                mState.accounts.remove(i);
            }
        }

        write();
        fireAccountsChanged();
    }

    public void addListener(Listener l) {
        mListeners.add(l);
    }

    public void removeListener(Listener l) {
        mListeners.remove(l);
    }

    private void fireAccountsChanged() {
        for (Listener l : mListeners) {
            l.onAccountsChanged(this);
        }
    }

    private void fireDefaultOutgoingChanged() {
        for (Listener l : mListeners) {
            l.onDefaultOutgoingChanged(this);
        }
    }

    private void fireSimCallManagerChanged() {
        for (Listener l : mListeners) {
            l.onSimCallManagerChanged(this);
        }
    }

    ////////////////////////////////////////////////////////////////////////////////////////////////

    // TODO: Add a corresponding has(...) method to class PhoneAccount itself and remove this one
    // Return true iff the given account has all the specified capability flags
    static boolean has(PhoneAccount account, int capability) {
        return (account.getCapabilities() & capability) == capability;
    }

    private List<PhoneAccountHandle> getCallProviderAccountHandles() {
        List<PhoneAccountHandle> accountHandles = new ArrayList<>();
        for (PhoneAccount m : mState.accounts) {
            if (has(m, PhoneAccount.CAPABILITY_CALL_PROVIDER)) {
                accountHandles.add(m.getAccountHandle());
            }
        }
        return accountHandles;
    }

    /**
     * The state of this {@code PhoneAccountRegistrar}.
     */
    @VisibleForTesting
    public static class State {
        /**
         * The account selected by the user to be employed by default for making outgoing calls.
         * If the user has not made such a selection, then this is null.
         */
        public PhoneAccountHandle defaultOutgoing = null;

        /**
         * A {@code PhoneAccount} having {@link PhoneAccount#CAPABILITY_CONNECTION_MANAGER} which
         * manages and optimizes a user's PSTN SIM connections.
         */
        public PhoneAccountHandle simCallManager;

        /**
         * The complete list of {@code PhoneAccount}s known to the Telecomm subsystem.
         */
        public final List<PhoneAccount> accounts = new ArrayList<>();
    }

    ////////////////////////////////////////////////////////////////////////////////////////////////
    //
    // State management
    //

    private void write() {
        final FileOutputStream os;
        try {
            os = mAtomicFile.startWrite();
            boolean success = false;
            try {
                XmlSerializer serializer = new FastXmlSerializer();
                serializer.setOutput(new BufferedOutputStream(os), "utf-8");
                writeToXml(mState, serializer);
                serializer.flush();
                success = true;
            } finally {
                if (success) {
                    mAtomicFile.finishWrite(os);
                } else {
                    mAtomicFile.failWrite(os);
                }
            }
        } catch (IOException e) {
            Log.e(this, e, "Writing state to XML file");
        }
    }

    private void read() {
        final InputStream is;
        try {
            is = mAtomicFile.openRead();
        } catch (FileNotFoundException ex) {
            return;
        }

        XmlPullParser parser;
        try {
            parser = Xml.newPullParser();
            parser.setInput(new BufferedInputStream(is), null);
            parser.nextTag();
            mState = readFromXml(parser);
        } catch (IOException | XmlPullParserException e) {
            Log.e(this, e, "Reading state from XML file");
            mState = new State();
        } finally {
            try {
                is.close();
            } catch (IOException e) {
                Log.e(this, e, "Closing InputStream");
            }
        }
    }

    private static void writeToXml(State state, XmlSerializer serializer)
            throws IOException {
        sStateXml.writeToXml(state, serializer);
    }

    private static State readFromXml(XmlPullParser parser)
            throws IOException, XmlPullParserException {
        State s = sStateXml.readFromXml(parser);
        return s != null ? s : new State();
    }

    ////////////////////////////////////////////////////////////////////////////////////////////////
    //
    // XML serialization
    //

    @VisibleForTesting
    public abstract static class XmlSerialization<T> {
        /**
         * Write the supplied object to XML
         */
        public abstract void writeToXml(T o, XmlSerializer serializer)
                throws IOException;

        /**
         * Read from the supplied XML into a new object, returning null in case of an
         * unrecoverable schema mismatch or other data error. 'parser' must be already
         * positioned at the first tag that is expected to have been emitted by this
         * object's writeToXml(). This object tries to fail early without modifying
         * 'parser' if it does not recognize the data it sees.
         */
        public abstract T readFromXml(XmlPullParser parser)
                throws IOException, XmlPullParserException;

        protected void writeTextSafely(String tagName, Object value, XmlSerializer serializer)
                throws IOException {
            if (value != null) {
                serializer.startTag(null, tagName);
                serializer.text(Objects.toString(value));
                serializer.endTag(null, tagName);
            }
        }
    }

    @VisibleForTesting
    public static final XmlSerialization<State> sStateXml =
            new XmlSerialization<State>() {
        private static final String CLASS_STATE = "phone_account_registrar_state";
        private static final String DEFAULT_OUTGOING = "default_outgoing";
        private static final String SIM_CALL_MANAGER = "sim_call_manager";
        private static final String ACCOUNTS = "accounts";

        @Override
        public void writeToXml(State o, XmlSerializer serializer)
                throws IOException {
            if (o != null) {
                serializer.startTag(null, CLASS_STATE);

                if (o.defaultOutgoing != null) {
                    serializer.startTag(null, DEFAULT_OUTGOING);
                    sPhoneAccountHandleXml.writeToXml(o.defaultOutgoing, serializer);
                    serializer.endTag(null, DEFAULT_OUTGOING);
                }

                if (o.simCallManager != null) {
                    serializer.startTag(null, SIM_CALL_MANAGER);
                    sPhoneAccountHandleXml.writeToXml(o.simCallManager, serializer);
                    serializer.endTag(null, SIM_CALL_MANAGER);
                }

                serializer.startTag(null, ACCOUNTS);
                for (PhoneAccount m : o.accounts) {
                    sPhoneAccountXml.writeToXml(m, serializer);
                }
                serializer.endTag(null, ACCOUNTS);

                serializer.endTag(null, CLASS_STATE);
            }
        }

        @Override
        public State readFromXml(XmlPullParser parser)
                throws IOException, XmlPullParserException {
            if (parser.getName().equals(CLASS_STATE)) {
                State s = new State();
                int outerDepth = parser.getDepth();
                while (XmlUtils.nextElementWithin(parser, outerDepth)) {
                    if (parser.getName().equals(DEFAULT_OUTGOING)) {
                        parser.nextTag();
                        s.defaultOutgoing = sPhoneAccountHandleXml.readFromXml(parser);
                    } else if (parser.getName().equals(SIM_CALL_MANAGER)) {
                        parser.nextTag();
                        s.simCallManager = sPhoneAccountHandleXml.readFromXml(parser);
                    } else if (parser.getName().equals(ACCOUNTS)) {
                        int accountsDepth = parser.getDepth();
                        while (XmlUtils.nextElementWithin(parser, accountsDepth)) {
                            PhoneAccount account = sPhoneAccountXml.readFromXml(parser);
                            if (account != null) {
                                s.accounts.add(account);
                            }
                        }
                    }
                }
                return s;
            }
            return null;
        }
    };

    @VisibleForTesting
    public static final XmlSerialization<PhoneAccount> sPhoneAccountXml =
            new XmlSerialization<PhoneAccount>() {
        private static final String CLASS_PHONE_ACCOUNT = "phone_account";
        private static final String ACCOUNT_HANDLE = "account_handle";
        private static final String HANDLE = "handle";
        private static final String SUBSCRIPTION_NUMBER = "subscription_number";
        private static final String CAPABILITIES = "capabilities";
        private static final String ICON_RES_ID = "icon_res_id";
        private static final String LABEL = "label";
        private static final String SHORT_DESCRIPTION = "short_description";

        @Override
        public void writeToXml(PhoneAccount o, XmlSerializer serializer)
                throws IOException {
            if (o != null) {
                serializer.startTag(null, CLASS_PHONE_ACCOUNT);

                if (o.getAccountHandle() != null) {
                    serializer.startTag(null, ACCOUNT_HANDLE);
                    sPhoneAccountHandleXml.writeToXml(o.getAccountHandle(), serializer);
                    serializer.endTag(null, ACCOUNT_HANDLE);
                }

                writeTextSafely(HANDLE, o.getHandle(), serializer);
                writeTextSafely(SUBSCRIPTION_NUMBER, o.getSubscriptionNumber(), serializer);
                writeTextSafely(CAPABILITIES, Integer.toString(o.getCapabilities()), serializer);
                writeTextSafely(ICON_RES_ID, Integer.toString(o.getIconResId()), serializer);
                writeTextSafely(LABEL, o.getLabel(), serializer);
                writeTextSafely(SHORT_DESCRIPTION, o.getShortDescription(), serializer);

                serializer.endTag(null, CLASS_PHONE_ACCOUNT);
            }
        }

        @Override
        public PhoneAccount readFromXml(XmlPullParser parser)
                throws IOException, XmlPullParserException {
            if (parser.getName().equals(CLASS_PHONE_ACCOUNT)) {
                int outerDepth = parser.getDepth();
                PhoneAccountHandle accountHandle = null;
                Uri handle = null;
                String subscriptionNumber = null;
                int capabilities = 0;
                int iconResId = 0;
                String label = null;
                String shortDescription = null;

                while (XmlUtils.nextElementWithin(parser, outerDepth)) {
                    if (parser.getName().equals(ACCOUNT_HANDLE)) {
                        parser.nextTag();
                        accountHandle = sPhoneAccountHandleXml.readFromXml(parser);
                    } else if (parser.getName().equals(HANDLE)) {
                        parser.next();
                        handle = Uri.parse(parser.getText());
                    } else if (parser.getName().equals(SUBSCRIPTION_NUMBER)) {
                        parser.next();
                        subscriptionNumber = parser.getText();
                    } else if (parser.getName().equals(CAPABILITIES)) {
                        parser.next();
                        capabilities = Integer.parseInt(parser.getText());
                    } else if (parser.getName().equals(ICON_RES_ID)) {
                        parser.next();
                        iconResId = Integer.parseInt(parser.getText());
                    } else if (parser.getName().equals(LABEL)) {
                        parser.next();
                        label = parser.getText();
                    } else if (parser.getName().equals(SHORT_DESCRIPTION)) {
                        parser.next();
                        shortDescription = parser.getText();
                    }
                }
                return new PhoneAccount(
                        accountHandle,
                        handle,
                        subscriptionNumber,
                        capabilities,
                        iconResId,
                        label,
                        shortDescription);
            }
            return null;
        }
    };

    @VisibleForTesting
    public static final XmlSerialization<PhoneAccountHandle> sPhoneAccountHandleXml =
            new XmlSerialization<PhoneAccountHandle>() {
        private static final String CLASS_PHONE_ACCOUNT_HANDLE = "phone_account_handle";
        private static final String COMPONENT_NAME = "component_name";
        private static final String ID = "id";

        @Override
        public void writeToXml(PhoneAccountHandle o, XmlSerializer serializer)
                throws IOException {
            if (o != null) {
                serializer.startTag(null, CLASS_PHONE_ACCOUNT_HANDLE);

                if (o.getComponentName() != null) {
                    writeTextSafely(
                            COMPONENT_NAME, o.getComponentName().flattenToString(), serializer);
                }

                writeTextSafely(ID, o.getId(), serializer);

                serializer.endTag(null, CLASS_PHONE_ACCOUNT_HANDLE);
            }
        }

        @Override
        public PhoneAccountHandle readFromXml(XmlPullParser parser)
                throws IOException, XmlPullParserException {
            if (parser.getName().equals(CLASS_PHONE_ACCOUNT_HANDLE)) {
                String componentNameString = null;
                String idString = null;
                int outerDepth = parser.getDepth();
                while (XmlUtils.nextElementWithin(parser, outerDepth)) {
                    if (parser.getName().equals(COMPONENT_NAME)) {
                        parser.next();
                        componentNameString = parser.getText();
                    } else if (parser.getName().equals(ID)) {
                        parser.next();
                        idString = parser.getText();
                    }
                }
                if (componentNameString != null) {
                    return new PhoneAccountHandle(
                            ComponentName.unflattenFromString(componentNameString),
                            idString);
                }
            }
            return null;
        }
    };
}