/* SecurityUtil.java
   Copyright (C) 2008 Red Hat, Inc.

This file is part of IcedTea.

IcedTea 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, version 2.

IcedTea 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
IcedTea; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is making a
combined work based on this library. Thus, the terms and conditions of the GNU
General Public License cover the whole combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent modules, and
to copy and distribute the resulting executable under terms of your choice,
provided that you also meet, for each linked independent module, the terms and
conditions of the license of that module. An independent module is a module
which is not derived from or based on this library. If you modify this library,
you may extend this exception to your version of the library, but you are not
obligated to do so. If you do not wish to do so, delete this exception
statement from your version.
*/

package net.sourceforge.jnlp.security;

import net.adoptopenjdk.icedteaweb.IcedTeaWebConstants;
import net.adoptopenjdk.icedteaweb.JavaSystemProperties;
import net.adoptopenjdk.icedteaweb.logging.Logger;
import net.adoptopenjdk.icedteaweb.logging.LoggerFactory;
import net.sourceforge.jnlp.security.KeyStores.Level;
import net.sourceforge.jnlp.security.KeyStores.Type;

import javax.net.ssl.KeyManagerFactory;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.security.Key;
import java.security.KeyStore;
import java.security.KeyStoreException;
import java.security.NoSuchAlgorithmException;
import java.security.UnrecoverableKeyException;
import java.security.cert.Certificate;
import java.security.cert.CertificateException;

import static net.adoptopenjdk.icedteaweb.JavaSystemPropertiesConstants.SSL_TRUST_STORE;
import static net.adoptopenjdk.icedteaweb.JavaSystemPropertiesConstants.SSL_TRUST_STORE_PASSWORD;
import static net.adoptopenjdk.icedteaweb.JavaSystemPropertiesConstants.SSL_TRUST_STORE_TYPE;

public class SecurityUtil {

    private final static Logger LOG = LoggerFactory.getLogger(SecurityUtil.class);

  
    public static String getTrustedCertsFilename() throws Exception {
        return KeyStores.getKeyStoreLocation(Level.USER, Type.CERTS).getFullPath();
    }


    /**
     * Extracts the CN field from a Certificate principal string. Or, if it
     * can't find that, return the principal unmodified.
     *
     * This is a simple (and hence 'wrong') version. See
     * http://www.ietf.org/rfc/rfc2253.txt for all the gory details.
     * @param principal string, CN to be extracted from
     * @return extracted CN
     */
    public static String getCN(String principal) {

        /*
         * FIXME Incomplete
         *
         * This does not implement RFC 2253 completely
         *
         * Issues:
         * - rfc2253 talks about utf8, java uses utf16.
         * - theoretically, java should have dealt with all byte encodings
         *   so we shouldn't even see cases like \FF
         * - if the above is wrong, then we need to deal with cases like
         *   \FF\FF
         */

        int start = principal.indexOf("CN=");
        if (start == -1) {
            return principal;
        }

        StringBuilder commonName = new StringBuilder();

        boolean inQuotes = false;
        boolean escaped = false;

        /*
         * bit 0 = high order bit. bit 1 = low order bit
         */
        char[] hexBits = null;

        for (int i = start + 3; i < principal.length(); i++) {
            char ch = principal.charAt(i);
            switch (ch) {
                case '"':
                    if (escaped) {
                        commonName.append(ch);
                        escaped = false;
                    } else {
                        inQuotes = !inQuotes;
                    }
                    break;

                case '\\':
                    if (escaped) {
                        commonName.append(ch);
                        escaped = false;
                    } else {
                        escaped = true;
                    }
                    break;

                case ',':
                    /* fall through */
                case ';':
                    /* fall through */
                case '+':
                    if (escaped || inQuotes) {
                        commonName.append(ch);
                        if (escaped) {
                            escaped = false;
                        }
                    } else {
                        return commonName.toString();
                    }
                    break;

                default:
                    if (escaped && isHexDigit(ch)) {
                        hexBits = new char[2];
                        hexBits[0] = ch;
                    } else if (hexBits != null) {
                        if (!isHexDigit(ch)) {
                            /* error parsing */
                            return "";
                        }
                        hexBits[1] = ch;
                        commonName.append((char) Integer.parseInt(new String(hexBits), 16));
                        hexBits = null;
                    } else {
                        commonName.append(ch);
                    }
                    escaped = false;
            }
        }

        return commonName.toString();

    }

    private static boolean isHexDigit(char ch) {
        return ((ch >= '0' && ch <= '9') || (ch >= 'A' && ch <= 'F') || (ch >= 'a' && ch <= 'f'));
    }

    /**
     * Checks the user's home directory to see if the trusted.certs file exists.
     * If it does not exist, it tries to create an empty keystore.
     * @return true if the trusted.certs file exists or a new trusted.certs
     * was created successfully, otherwise false.
     * @throws java.lang.Exception if check goes wrong
     */
    public static boolean checkTrustedCertsFile() throws Exception {

        File certFile = new File(getTrustedCertsFilename());

        //file does not exist
        if (!certFile.isFile()) {
            File dir = certFile.getAbsoluteFile().getParentFile();
            boolean madeDir = false;
            if (!dir.isDirectory()) {
                madeDir = dir.mkdirs();
            }

            //made directory, or directory exists
            if (madeDir || dir.isDirectory()) {
                KeyStore ks = KeyStore.getInstance("JKS");
                loadKeyStore(ks, null);
                storeKeyStore(ks, certFile);
                return true;
            } else {
                return false;
            }
        } else {
            return true;
        }
    }

    /**
     * @return the keystore associated with the user's trusted.certs file,
     * or null otherwise.
     * @throws java.lang.Exception if getting fails
     */
    public static KeyStore getUserKeyStore() throws Exception {

        KeyStore ks = null;
        FileInputStream fis = null;

        if (checkTrustedCertsFile()) {

            try {
                File file = new File(getTrustedCertsFilename());
                if (file.exists()) {
                    ks = KeyStore.getInstance("JKS");
                    loadKeyStore(ks, file);
                }
            } catch (Exception e) {
                LOG.error(IcedTeaWebConstants.DEFAULT_ERROR_MESSAGE, e);
                throw e;
            } finally {
                if (fis != null)
                    fis.close();
            }
        }
        return ks;
    }

    /**
     * @return the keystore associated with the JDK cacerts file,
     * or null otherwise.
     * @throws java.lang.Exception if get fails
     */
    public static KeyStore getCacertsKeyStore() throws Exception {

        KeyStore caks = null;
        FileInputStream fis = null;

        try {
            File file = new File(JavaSystemProperties.getJavaHome()
                                + "/lib/security/cacerts");
            if (file.exists()) {
                fis = new FileInputStream(file);
                caks = KeyStore.getInstance("JKS");
                caks.load(fis, null);
            }
        } catch (Exception e) {
            caks = null;
        } finally {
            if (fis != null)
                fis.close();
        }

        return caks;
    }

    /**
     * @return the keystore associated with the system certs file,
     * or null otherwise.
     * @throws java.lang.Exception if get goes wrong
     */
    public static KeyStore getSystemCertStore() throws Exception {

        KeyStore caks = null;
        FileInputStream fis = null;

        try {
            File file = new File(System.getProperty(SSL_TRUST_STORE));
            String type = System.getProperty(SSL_TRUST_STORE_TYPE);
            //String provider = "SUN";
            char[] password = System.getProperty(SSL_TRUST_STORE_PASSWORD).toCharArray();
            if (file.exists()) {
                fis = new FileInputStream(file);
                caks = KeyStore.getInstance(type);
                caks.load(fis, password);
            }
        } catch (Exception e) {
            caks = null;
        } finally {
            if (fis != null)
                fis.close();
        }

        return caks;
    }
    
     public static void initKeyManagerFactory(KeyManagerFactory kmf, KeyStore ks) throws KeyStoreException, NoSuchAlgorithmException, UnrecoverableKeyException {
        try {
            KeystorePasswordAttempter.INSTANCE.unlockKeystore(
                    new KeystorePasswordAttempter.KeystoreOperation(kmf, ks) {

                        @Override
                        String getId() {
                            return "'init keymanager-factory'";
                        }

                        @Override
                        Key operateKeystore(char[] pass) throws KeyStoreException, NoSuchAlgorithmException, UnrecoverableKeyException, IOException, CertificateException {
                            kmf.init(ks, pass);
                            return null;
                        }
                    });
        } catch (IOException | CertificateException ex) {
            throw unexpectedException(ex);
        }
    }

    public static void setKeyEntry(KeyStore ks, String alias, Key key, Certificate[] certChain) throws KeyStoreException {
        try {
            KeystorePasswordAttempter.INSTANCE.unlockKeystore(
                    new KeystorePasswordAttempter.KeystoreOperation(ks, alias, key, certChain) {

                @Override
                String getId() {
                    return "'set key entry'";
                }

                @Override
                Key operateKeystore(char[] pass) throws KeyStoreException, NoSuchAlgorithmException, UnrecoverableKeyException, IOException, CertificateException {
                    ks.setKeyEntry(alias, key, pass, certChain);
                    return null;
                }
            });
        } catch (NoSuchAlgorithmException | UnrecoverableKeyException | IOException | CertificateException ex) {
            throw unexpectedException(ex);
        }
    }

    public static Key getKey(KeyStore ks, String alias) throws KeyStoreException, NoSuchAlgorithmException, UnrecoverableKeyException {
        try {
            return KeystorePasswordAttempter.INSTANCE.unlockKeystore(
                    new KeystorePasswordAttempter.KeystoreOperation(ks, alias, null, null) {

                        @Override
                        String getId() {
                            return "'get key'";
                        }

                        @Override
                        Key operateKeystore(char[] pass) throws KeyStoreException, NoSuchAlgorithmException, UnrecoverableKeyException, IOException, CertificateException {
                            return ks.getKey(alias, pass);
                        }
                    });
        } catch (IOException | CertificateException ex) {
            throw unexpectedException(ex);
        }
    }

    public static void loadKeyStore(KeyStore ks, File f) throws IOException, NoSuchAlgorithmException, CertificateException {
        try {
            KeystorePasswordAttempter.INSTANCE.unlockKeystore(
                    new KeystorePasswordAttempter.KeystoreOperation(ks, f) {

                        @Override
                        String getId() {
                            return "'load keystore'";
                        }

                        @Override
                        Key operateKeystore(char[] pass) throws KeyStoreException, NoSuchAlgorithmException, UnrecoverableKeyException, IOException, CertificateException {
                            if (f == null) {
                                ks.load(null, pass);
                            } else {
                                try (FileInputStream fis = new FileInputStream(f)) {
                                    ks.load(fis, pass);
                                }
                            }
                            return null;
                        }
                    });
        } catch (KeyStoreException | UnrecoverableKeyException ex) {
            throw unexpectedException(ex);
        }

    }

    public static void storeKeyStore(KeyStore ks, File f) throws KeyStoreException, IOException, NoSuchAlgorithmException, CertificateException {
        try {
            KeystorePasswordAttempter.INSTANCE.unlockKeystore(
                    new KeystorePasswordAttempter.KeystoreOperation(ks, f) {

                        @Override
                        String getId() {
                            return "'store keystore'";
                        }

                        @Override
                        Key operateKeystore(char[] pass) throws KeyStoreException, NoSuchAlgorithmException, UnrecoverableKeyException, IOException, CertificateException {
                            if (f == null) {
                                ks.store(null, pass);
                            } else {
                                try (FileOutputStream fos = new FileOutputStream(f)) {
                                    ks.store(fos, pass);
                                }
                            }
                            return null;
                        }
                    });
        } catch (UnrecoverableKeyException ex) {
            throw unexpectedException(ex);
        }
    }

    private static RuntimeException unexpectedException(Exception ex) {
        return new RuntimeException("This usage of KeystorePasswordAttempter should not throw this kind of exception", ex);
    }

}
