/*
 * Copyright (C) 2009 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 android.security;

import android.net.LocalSocketAddress;
import android.net.LocalSocket;

import java.io.InputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.UTFDataFormatException;
import java.nio.charset.Charsets;
import java.nio.charset.ModifiedUtf8;
import java.util.ArrayList;
import java.util.Date;

/**
 * @hide This should not be made public in its present form because it
 * assumes that private and secret key bytes are available and would
 * preclude the use of hardware crypto.
 */
public class KeyStore {

    // ResponseCodes
    public static final int NO_ERROR = 1;
    public static final int LOCKED = 2;
    public static final int UNINITIALIZED = 3;
    public static final int SYSTEM_ERROR = 4;
    public static final int PROTOCOL_ERROR = 5;
    public static final int PERMISSION_DENIED = 6;
    public static final int KEY_NOT_FOUND = 7;
    public static final int VALUE_CORRUPTED = 8;
    public static final int UNDEFINED_ACTION = 9;
    public static final int WRONG_PASSWORD = 10;

    // States
    public enum State { UNLOCKED, LOCKED, UNINITIALIZED };

    private static final LocalSocketAddress sAddress = new LocalSocketAddress(
            "keystore", LocalSocketAddress.Namespace.RESERVED);

    private int mError = NO_ERROR;

    private KeyStore() {}

    public static KeyStore getInstance() {
        return new KeyStore();
    }

    public State state() {
        execute('t');
        switch (mError) {
            case NO_ERROR: return State.UNLOCKED;
            case LOCKED: return State.LOCKED;
            case UNINITIALIZED: return State.UNINITIALIZED;
            default: throw new AssertionError(mError);
        }
    }

    private byte[] get(byte[] key) {
        ArrayList<byte[]> values = execute('g', key);
        return (values == null || values.isEmpty()) ? null : values.get(0);
    }

    public byte[] get(String key) {
        return get(getKeyBytes(key));
    }

    private boolean put(byte[] key, byte[] value) {
        execute('i', key, value);
        return mError == NO_ERROR;
    }

    public boolean put(String key, byte[] value) {
        return put(getKeyBytes(key), value);
    }

    private boolean delete(byte[] key) {
        execute('d', key);
        return mError == NO_ERROR;
    }

    public boolean delete(String key) {
        return delete(getKeyBytes(key));
    }

    private boolean contains(byte[] key) {
        execute('e', key);
        return mError == NO_ERROR;
    }

    public boolean contains(String key) {
        return contains(getKeyBytes(key));
    }

    public byte[][] saw(byte[] prefix) {
        ArrayList<byte[]> values = execute('s', prefix);
        return (values == null) ? null : values.toArray(new byte[values.size()][]);
    }

    public String[] saw(String prefix) {
        byte[][] values = saw(getKeyBytes(prefix));
        if (values == null) {
            return null;
        }
        String[] strings = new String[values.length];
        for (int i = 0; i < values.length; ++i) {
            strings[i] = toKeyString(values[i]);
        }
        return strings;
    }

    public boolean reset() {
        execute('r');
        return mError == NO_ERROR;
    }

    private boolean password(byte[] password) {
        execute('p', password);
        return mError == NO_ERROR;
    }

    public boolean password(String password) {
        return password(getPasswordBytes(password));
    }

    public boolean lock() {
        execute('l');
        return mError == NO_ERROR;
    }

    private boolean unlock(byte[] password) {
        execute('u', password);
        return mError == NO_ERROR;
    }

    public boolean unlock(String password) {
        return unlock(getPasswordBytes(password));
    }

    public boolean isEmpty() {
        execute('z');
        return mError == KEY_NOT_FOUND;
    }

    private boolean generate(byte[] key) {
        execute('a', key);
        return mError == NO_ERROR;
    }

    public boolean generate(String key) {
        return generate(getKeyBytes(key));
    }

    private boolean importKey(byte[] keyName, byte[] key) {
        execute('m', keyName, key);
        return mError == NO_ERROR;
    }

    public boolean importKey(String keyName, byte[] key) {
        return importKey(getKeyBytes(keyName), key);
    }

    private byte[] getPubkey(byte[] key) {
        ArrayList<byte[]> values = execute('b', key);
        return (values == null || values.isEmpty()) ? null : values.get(0);
    }

    public byte[] getPubkey(String key) {
        return getPubkey(getKeyBytes(key));
    }

    private boolean delKey(byte[] key) {
        execute('k', key);
        return mError == NO_ERROR;
    }

    public boolean delKey(String key) {
        return delKey(getKeyBytes(key));
    }

    private byte[] sign(byte[] keyName, byte[] data) {
        final ArrayList<byte[]> values = execute('n', keyName, data);
        return (values == null || values.isEmpty()) ? null : values.get(0);
    }

    public byte[] sign(String key, byte[] data) {
        return sign(getKeyBytes(key), data);
    }

    private boolean verify(byte[] keyName, byte[] data, byte[] signature) {
        execute('v', keyName, data, signature);
        return mError == NO_ERROR;
    }

    public boolean verify(String key, byte[] data, byte[] signature) {
        return verify(getKeyBytes(key), data, signature);
    }

    private boolean grant(byte[] key, byte[] uid) {
        execute('x', key, uid);
        return mError == NO_ERROR;
    }

    public boolean grant(String key, int uid) {
         return grant(getKeyBytes(key), getUidBytes(uid));
    }

    private boolean ungrant(byte[] key, byte[] uid) {
        execute('y', key, uid);
        return mError == NO_ERROR;
    }

    public boolean ungrant(String key, int uid) {
        return ungrant(getKeyBytes(key), getUidBytes(uid));
    }

    private long getmtime(byte[] key) {
        final ArrayList<byte[]> values = execute('c', key);
        if (values == null || values.isEmpty()) {
            return -1L;
        }

        return Long.parseLong(new String(values.get(0))) * 1000L;
    }

    /**
     * Returns the last modification time of the key in milliseconds since the
     * epoch. Will return -1L if the key could not be found or other error.
     */
    public long getmtime(String key) {
        return getmtime(getKeyBytes(key));
    }

    public int getLastError() {
        return mError;
    }

    private ArrayList<byte[]> execute(int code, byte[]... parameters) {
        mError = PROTOCOL_ERROR;

        for (byte[] parameter : parameters) {
            if (parameter == null || parameter.length > 65535) {
                return null;
            }
        }

        LocalSocket socket = new LocalSocket();
        try {
            socket.connect(sAddress);

            OutputStream out = socket.getOutputStream();
            out.write(code);
            for (byte[] parameter : parameters) {
                out.write(parameter.length >> 8);
                out.write(parameter.length);
                out.write(parameter);
            }
            out.flush();
            socket.shutdownOutput();

            InputStream in = socket.getInputStream();
            if ((code = in.read()) != NO_ERROR) {
                if (code != -1) {
                    mError = code;
                }
                return null;
            }

            ArrayList<byte[]> values = new ArrayList<byte[]>();
            while (true) {
                int i, j;
                if ((i = in.read()) == -1) {
                    break;
                }
                if ((j = in.read()) == -1) {
                    return null;
                }
                byte[] value = new byte[i << 8 | j];
                for (i = 0; i < value.length; i += j) {
                    if ((j = in.read(value, i, value.length - i)) == -1) {
                        return null;
                    }
                }
                values.add(value);
            }
            mError = NO_ERROR;
            return values;
        } catch (IOException e) {
            // ignore
        } finally {
            try {
                socket.close();
            } catch (IOException e) {}
        }
        return null;
    }

    /**
     * ModifiedUtf8 is used for key encoding to match the
     * implementation of NativeCrypto.ENGINE_load_private_key.
     */
    private static byte[] getKeyBytes(String string) {
        try {
            int utfCount = (int) ModifiedUtf8.countBytes(string, false);
            byte[] result = new byte[utfCount];
            ModifiedUtf8.encode(result, 0, string);
            return result;
        } catch (UTFDataFormatException e) {
            throw new RuntimeException(e);
        }
    }

    private static String toKeyString(byte[] bytes) {
        try {
            return ModifiedUtf8.decode(bytes, new char[bytes.length], 0, bytes.length);
        } catch (UTFDataFormatException e) {
            throw new RuntimeException(e);
        }
    }

    private static byte[] getPasswordBytes(String password) {
        return password.getBytes(Charsets.UTF_8);
    }

    private static byte[] getUidBytes(int uid) {
        return Integer.toString(uid).getBytes(Charsets.UTF_8);
    }
}