/*
 * Copyright (C) 2012 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 org.bouncycastle.jce.provider;

import java.io.Closeable;
import java.io.ByteArrayOutputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.math.BigInteger;
import java.security.PublicKey;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashSet;
import java.util.Set;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.bouncycastle.crypto.Digest;
import org.bouncycastle.crypto.digests.AndroidDigestFactory;
import org.bouncycastle.util.encoders.Hex;

public class CertBlacklist {

    private static final String ANDROID_DATA = System.getenv("ANDROID_DATA");
    private static final String BLACKLIST_ROOT = ANDROID_DATA + "/misc/keychain/";
    public static final String DEFAULT_PUBKEY_BLACKLIST_PATH = BLACKLIST_ROOT + "pubkey_blacklist.txt";
    public static final String DEFAULT_SERIAL_BLACKLIST_PATH = BLACKLIST_ROOT + "serial_blacklist.txt";

    private static final Logger logger = Logger.getLogger(CertBlacklist.class.getName());

    // public for testing
    public final Set<BigInteger> serialBlacklist;
    public final Set<byte[]> pubkeyBlacklist;

    public CertBlacklist() {
        this(DEFAULT_PUBKEY_BLACKLIST_PATH, DEFAULT_SERIAL_BLACKLIST_PATH);
    }

    /** Test only interface, not for public use */
    public CertBlacklist(String pubkeyBlacklistPath, String serialBlacklistPath) {
        serialBlacklist = readSerialBlackList(serialBlacklistPath);
        pubkeyBlacklist = readPublicKeyBlackList(pubkeyBlacklistPath);
    }

    private static boolean isHex(String value) {
        try {
            new BigInteger(value, 16);
            return true;
        } catch (NumberFormatException e) {
            logger.log(Level.WARNING, "Could not parse hex value " + value, e);
            return false;
        }
    }

    private static boolean isPubkeyHash(String value) {
        if (value.length() != 40) {
            logger.log(Level.WARNING, "Invalid pubkey hash length: " + value.length());
            return false;
        }
        return isHex(value);
    }

    private static String readBlacklist(String path) {
        try {
            return readFileAsString(path);
        } catch (FileNotFoundException ignored) {
        } catch (IOException e) {
            logger.log(Level.WARNING, "Could not read blacklist", e);
        }
        return "";
    }

    // From IoUtils.readFileAsString
    private static String readFileAsString(String path) throws IOException {
        return readFileAsBytes(path).toString("UTF-8");
    }

    // Based on IoUtils.readFileAsBytes
    private static ByteArrayOutputStream readFileAsBytes(String path) throws IOException {
        RandomAccessFile f = null;
        try {
            f = new RandomAccessFile(path, "r");
            ByteArrayOutputStream bytes = new ByteArrayOutputStream((int) f.length());
            byte[] buffer = new byte[8192];
            while (true) {
                int byteCount = f.read(buffer);
                if (byteCount == -1) {
                    return bytes;
                }
                bytes.write(buffer, 0, byteCount);
            }
        } finally {
            closeQuietly(f);
        }
    }

    // Base on IoUtils.closeQuietly
    private static void closeQuietly(Closeable closeable) {
        if (closeable != null) {
            try {
                closeable.close();
            } catch (RuntimeException rethrown) {
                throw rethrown;
            } catch (Exception ignored) {
            }
        }
    }

    private static final Set<BigInteger> readSerialBlackList(String path) {

        // start out with a base set of known bad values
        Set<BigInteger> bl = new HashSet<BigInteger>(Arrays.asList(
            // From http://src.chromium.org/viewvc/chrome/trunk/src/net/base/x509_certificate.cc?revision=78748&view=markup
            // Not a real certificate. For testing only.
            new BigInteger("077a59bcd53459601ca6907267a6dd1c", 16),
            new BigInteger("047ecbe9fca55f7bd09eae36e10cae1e", 16),
            new BigInteger("d8f35f4eb7872b2dab0692e315382fb0", 16),
            new BigInteger("b0b7133ed096f9b56fae91c874bd3ac0", 16),
            new BigInteger("9239d5348f40d1695a745470e1f23f43", 16),
            new BigInteger("e9028b9578e415dc1a710a2b88154447", 16),
            new BigInteger("d7558fdaf5f1105bb213282b707729a3", 16),
            new BigInteger("f5c86af36162f13a64f54f6dc9587c06", 16),
            new BigInteger("392a434f0e07df1f8aa305de34e0c229", 16),
            new BigInteger("3e75ced46b693021218830ae86a82a71", 16),
            new BigInteger("864", 16),
            new BigInteger("827", 16),
            new BigInteger("31da7", 16)
        ));

        // attempt to augment it with values taken from gservices
        String serialBlacklist = readBlacklist(path);
        if (!serialBlacklist.equals("")) {
            for(String value : serialBlacklist.split(",")) {
                try {
                    bl.add(new BigInteger(value, 16));
                } catch (NumberFormatException e) {
                    logger.log(Level.WARNING, "Tried to blacklist invalid serial number " + value, e);
                }
            }
        }

        // whether that succeeds or fails, send it on its merry way
        return Collections.unmodifiableSet(bl);
    }

    private static final Set<byte[]> readPublicKeyBlackList(String path) {

        // start out with a base set of known bad values
        Set<byte[]> bl = new HashSet<byte[]>(Arrays.asList(
            // From http://src.chromium.org/viewvc/chrome/branches/782/src/net/base/x509_certificate.cc?r1=98750&r2=98749&pathrev=98750
            // C=NL, O=DigiNotar, CN=DigiNotar Root CA/emailAddress=info@diginotar.nl
            "410f36363258f30b347d12ce4863e433437806a8".getBytes(),
            // Subject: CN=DigiNotar Cyber CA
            // Issuer: CN=GTE CyberTrust Global Root
            "ba3e7bd38cd7e1e6b9cd4c219962e59d7a2f4e37".getBytes(),
            // Subject: CN=DigiNotar Services 1024 CA
            // Issuer: CN=Entrust.net
            "e23b8d105f87710a68d9248050ebefc627be4ca6".getBytes(),
            // Subject: CN=DigiNotar PKIoverheid CA Organisatie - G2
            // Issuer: CN=Staat der Nederlanden Organisatie CA - G2
            "7b2e16bc39bcd72b456e9f055d1de615b74945db".getBytes(),
            // Subject: CN=DigiNotar PKIoverheid CA Overheid en Bedrijven
            // Issuer: CN=Staat der Nederlanden Overheid CA
            "e8f91200c65cee16e039b9f883841661635f81c5".getBytes(),
            // From http://src.chromium.org/viewvc/chrome?view=rev&revision=108479
            // Subject: O=Digicert Sdn. Bhd.
            // Issuer: CN=GTE CyberTrust Global Root
            "0129bcd5b448ae8d2496d1c3e19723919088e152".getBytes(),
            // Subject: CN=e-islem.kktcmerkezbankasi.org/emailAddress=ileti@kktcmerkezbankasi.org
            // Issuer: CN=T\xC3\x9CRKTRUST Elektronik Sunucu Sertifikas\xC4\xB1 Hizmetleri
            "5f3ab33d55007054bc5e3e5553cd8d8465d77c61".getBytes(),
            // Subject: CN=*.EGO.GOV.TR 93
            // Issuer: CN=T\xC3\x9CRKTRUST Elektronik Sunucu Sertifikas\xC4\xB1 Hizmetleri
            "783333c9687df63377efceddd82efa9101913e8e".getBytes(),
            // Subject: Subject: C=FR, O=DG Tr\xC3\xA9sor, CN=AC DG Tr\xC3\xA9sor SSL
            // Issuer: C=FR, O=DGTPE, CN=AC DGTPE Signature Authentification
            "3ecf4bbbe46096d514bb539bb913d77aa4ef31bf".getBytes()
        ));

        // attempt to augment it with values taken from gservices
        String pubkeyBlacklist = readBlacklist(path);
        if (!pubkeyBlacklist.equals("")) {
            for (String value : pubkeyBlacklist.split(",")) {
                value = value.trim();
                if (isPubkeyHash(value)) {
                    bl.add(value.getBytes());
                } else {
                    logger.log(Level.WARNING, "Tried to blacklist invalid pubkey " + value);
                }
            }
        }

        return bl;
    }

    public boolean isPublicKeyBlackListed(PublicKey publicKey) {
        byte[] encoded = publicKey.getEncoded();
        Digest digest = AndroidDigestFactory.getSHA1();
        digest.update(encoded, 0, encoded.length);
        byte[] out = new byte[digest.getDigestSize()];
        digest.doFinal(out, 0);
        for (byte[] blacklisted : pubkeyBlacklist) {
            if (Arrays.equals(blacklisted, Hex.encode(out))) {
                return true;
            }
        }
        return false;
    }

    public boolean isSerialNumberBlackListed(BigInteger serial) {
        return serialBlacklist.contains(serial);
    }

}