/*
    * Copyright 2016 The Netty Project
    *
    * The Netty Project licenses this file to you 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:
    *
    *   https://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 io.netty.handler.ssl;
  
  import java.security.PrivateKey;
  
  import javax.security.auth.Destroyable;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.ByteBufAllocator;
  import io.netty.buffer.Unpooled;
  import io.netty.util.AbstractReferenceCounted;
  import io.netty.util.CharsetUtil;
  import io.netty.util.IllegalReferenceCountException;
  import io.netty.util.internal.ObjectUtil;
  
  /**
   * This is a special purpose implementation of a {@link PrivateKey} which allows the
   * user to pass PEM/PKCS#8 encoded key material straight into {@link OpenSslContext}
   * without having to parse and re-encode bytes in Java land.
   *
   * All methods other than what's implemented in {@link PemEncoded} and {@link Destroyable}
   * throw {@link UnsupportedOperationException}s.
   *
   * @see PemEncoded
   * @see OpenSslContext
   * @see #valueOf(byte[])
   * @see #valueOf(ByteBuf)
   */
  public final class PemPrivateKey extends AbstractReferenceCounted implements PrivateKey, PemEncoded {
      private static final long serialVersionUID = 7978017465645018936L;
  
      private static final byte[] BEGIN_PRIVATE_KEY = "-----BEGIN PRIVATE KEY-----\n".getBytes(CharsetUtil.US_ASCII);
      private static final byte[] END_PRIVATE_KEY = "\n-----END PRIVATE KEY-----\n".getBytes(CharsetUtil.US_ASCII);
  
      private static final String PKCS8_FORMAT = "PKCS#8";
  
      /**
       * Creates a {@link PemEncoded} value from the {@link PrivateKey}.
       */
      static PemEncoded toPEM(ByteBufAllocator allocator, boolean useDirect, PrivateKey key) {
          // We can take a shortcut if the private key happens to be already
          // PEM/PKCS#8 encoded. This is the ideal case and reason why all
          // this exists. It allows the user to pass pre-encoded bytes straight
          // into OpenSSL without having to do any of the extra work.
          if (key instanceof PemEncoded) {
              return ((PemEncoded) key).retain();
          }
  
          byte[] bytes = key.getEncoded();
          if (bytes == null) {
              throw new IllegalArgumentException(key.getClass().getName() + " does not support encoding");
          }
  
          return toPEM(allocator, useDirect, bytes);
      }
  
      static PemEncoded toPEM(ByteBufAllocator allocator, boolean useDirect, byte[] bytes) {
          ByteBuf encoded = Unpooled.wrappedBuffer(bytes);
          try {
              ByteBuf base64 = SslUtils.toBase64(allocator, encoded);
              try {
                  int size = BEGIN_PRIVATE_KEY.length + base64.readableBytes() + END_PRIVATE_KEY.length;
  
                  boolean success = false;
                  final ByteBuf pem = useDirect ? allocator.directBuffer(size) : allocator.buffer(size);
                  try {
                      pem.writeBytes(BEGIN_PRIVATE_KEY);
                      pem.writeBytes(base64);
                      pem.writeBytes(END_PRIVATE_KEY);
  
                      PemValue value = new PemValue(pem, true);
                      success = true;
                      return value;
                  } finally {
                      // Make sure we never leak that PEM ByteBuf if there's an Exception.
                      if (!success) {
                          SslUtils.zerooutAndRelease(pem);
                      }
                  }
              } finally {
                  SslUtils.zerooutAndRelease(base64);
              }
          } finally {
              SslUtils.zerooutAndRelease(encoded);
          }
     }
 
     /**
      * Creates a {@link PemPrivateKey} from raw {@code byte[]}.
      *
      * ATTENTION: It's assumed that the given argument is a PEM/PKCS#8 encoded value.
      * No input validation is performed to validate it.
      */
     public static PemPrivateKey valueOf(byte[] key) {
         return valueOf(Unpooled.wrappedBuffer(key));
     }
 
     /**
      * Creates a {@link PemPrivateKey} from raw {@code ByteBuf}.
      *
      * ATTENTION: It's assumed that the given argument is a PEM/PKCS#8 encoded value.
      * No input validation is performed to validate it.
      */
     public static PemPrivateKey valueOf(ByteBuf key) {
         return new PemPrivateKey(key);
     }
 
     private final ByteBuf content;
 
     private PemPrivateKey(ByteBuf content) {
         this.content = ObjectUtil.checkNotNull(content, "content");
     }
 
     @Override
     public boolean isSensitive() {
         return true;
     }
 
     @Override
     public ByteBuf content() {
         int count = refCnt();
         if (count <= 0) {
             throw new IllegalReferenceCountException(count);
         }
 
         return content;
     }
 
     @Override
     public PemPrivateKey copy() {
         return replace(content.copy());
     }
 
     @Override
     public PemPrivateKey duplicate() {
         return replace(content.duplicate());
     }
 
     @Override
     public PemPrivateKey retainedDuplicate() {
         return replace(content.retainedDuplicate());
     }
 
     @Override
     public PemPrivateKey replace(ByteBuf content) {
         return new PemPrivateKey(content);
     }
 
     @Override
     public PemPrivateKey touch() {
         content.touch();
         return this;
     }
 
     @Override
     public PemPrivateKey touch(Object hint) {
         content.touch(hint);
         return this;
     }
 
     @Override
     public PemPrivateKey retain() {
         return (PemPrivateKey) super.retain();
     }
 
     @Override
     public PemPrivateKey retain(int increment) {
         return (PemPrivateKey) super.retain(increment);
     }
 
     @Override
     protected void deallocate() {
         // Private Keys are sensitive. We need to zero the bytes
         // before we're releasing the underlying ByteBuf
         SslUtils.zerooutAndRelease(content);
     }
 
     @Override
     public byte[] getEncoded() {
         throw new UnsupportedOperationException();
     }
 
     @Override
     public String getAlgorithm() {
         throw new UnsupportedOperationException();
     }
 
     @Override
     public String getFormat() {
         return PKCS8_FORMAT;
     }
 
     /**
      * NOTE: This is a JDK8 interface/method. Due to backwards compatibility
      * reasons it's not possible to slap the {@code @Override} annotation onto
      * this method.
      *
      * @see Destroyable#destroy()
      */
     @Override
     public void destroy() {
         release(refCnt());
     }
 
     /**
      * NOTE: This is a JDK8 interface/method. Due to backwards compatibility
      * reasons it's not possible to slap the {@code @Override} annotation onto
      * this method.
      *
      * @see Destroyable#isDestroyed()
      */
     @Override
     public boolean isDestroyed() {
         return refCnt() == 0;
     }
 }