/*
    * Copyright (c) 1996, 2010, Oracle and/or its affiliates. All rights reserved.
    * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
    *
    * This code is free software; you can redistribute it and/or modify it
    * under the terms of the GNU General Public License version 2 only, as
    * published by the Free Software Foundation.  Oracle designates this
    * particular file as subject to the "Classpath" exception as provided
    * by Oracle in the LICENSE file that accompanied this code.
   *
   * This code 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
   * version 2 for more details (a copy is included in the LICENSE file that
   * accompanied this code).
   *
   * You should have received a copy of the GNU General Public License version
   * 2 along with this work; if not, write to the Free Software Foundation,
   * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
   *
   * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
   * or visit www.oracle.com if you need additional information or have any
   * questions.
   */
  
  package sun.security.util;
  
  import java.io.ByteArrayOutputStream;
  import java.io.OutputStream;
  import java.io.IOException;
  import java.text.SimpleDateFormat;
  import java.util.Date;
  import java.util.TimeZone;
  import java.util.Comparator;
  import java.util.Arrays;
  import java.math.BigInteger;
  import java.util.Locale;
  
  
  /**
   * Output stream marshaling DER-encoded data.  This is eventually provided
   * in the form of a byte array; there is no advance limit on the size of
   * that byte array.
   *
   * <P>At this time, this class supports only a subset of the types of
   * DER data encodings which are defined.  That subset is sufficient for
   * generating most X.509 certificates.
   *
   *
   * @author David Brownell
   * @author Amit Kapoor
   * @author Hemma Prafullchandra
   */
  public class DerOutputStream
  extends ByteArrayOutputStream implements DerEncoder {
      /**
       * Construct an DER output stream.
       *
       * @param size how large a buffer to preallocate.
       */
      public DerOutputStream(int size) { super(size); }
  
      /**
       * Construct an DER output stream.
       */
      public DerOutputStream() { }
  
      /**
       * Writes tagged, pre-marshaled data.  This calcuates and encodes
       * the length, so that the output data is the standard triple of
       * { tag, length, data } used by all DER values.
       *
       * @param tag the DER value tag for the data, such as
       *          <em>DerValue.tag_Sequence</em>
       * @param buf buffered data, which must be DER-encoded
       */
      public void write(byte tag, byte[] buf) throws IOException {
          write(tag);
          putLength(buf.length);
          write(buf, 0, buf.length);
      }
  
      /**
       * Writes tagged data using buffer-to-buffer copy.  As above,
       * this writes a standard DER record.  This is often used when
       * efficiently encapsulating values in sequences.
       *
       * @param tag the DER value tag for the data, such as
       *          <em>DerValue.tag_Sequence</em>
       * @param out buffered data
       */
      public void write(byte tag, DerOutputStream out) throws IOException {
          write(tag);
          putLength(out.count);
          write(out.buf, 0, out.count);
      }
  
      /**
       * Writes implicitly tagged data using buffer-to-buffer copy.  As above,
      * this writes a standard DER record.  This is often used when
      * efficiently encapsulating implicitly tagged values.
      *
      * @param tag the DER value of the context-specific tag that replaces
      * original tag of the value in the output, such as in
      * <pre>
      *          <em> <field> [N] IMPLICIT <type></em>
      * </pre>
      * For example, <em>FooLength [1] IMPLICIT INTEGER</em>, with value=4;
      * would be encoded as "81 01 04"  whereas in explicit
      * tagging it would be encoded as "A1 03 02 01 04".
      * Notice that the tag is A1 and not 81, this is because with
      * explicit tagging the form is always constructed.
      * @param value original value being implicitly tagged
      */
     public void writeImplicit(byte tag, DerOutputStream value)
     throws IOException {
         write(tag);
         write(value.buf, 1, value.count-1);
     }
 
     /**
      * Marshals pre-encoded DER value onto the output stream.
      */
     public void putDerValue(DerValue val) throws IOException {
         val.encode(this);
     }
 
     /*
      * PRIMITIVES -- these are "universal" ASN.1 simple types.
      *
      *  BOOLEAN, INTEGER, BIT STRING, OCTET STRING, NULL
      *  OBJECT IDENTIFIER, SEQUENCE(OF), SET(OF)
      *  PrintableString, T61String, IA5String, UTCTime
      */
 
     /**
      * Marshals a DER boolean on the output stream.
      */
     public void putBoolean(boolean val) throws IOException {
         write(DerValue.tag_Boolean);
         putLength(1);
         if (val) {
             write(0xff);
         } else {
             write(0);
         }
     }
 
     /**
      * Marshals a DER enumerated on the output stream.
      * @param i the enumerated value.
      */
     public void putEnumerated(int i) throws IOException {
         write(DerValue.tag_Enumerated);
         putIntegerContents(i);
     }
 
     /**
      * Marshals a DER integer on the output stream.
      *
      * @param i the integer in the form of a BigInteger.
      */
     public void putInteger(BigInteger i) throws IOException {
         write(DerValue.tag_Integer);
         byte[]    buf = i.toByteArray(); // least number  of bytes
         putLength(buf.length);
         write(buf, 0, buf.length);
     }
 
     /**
      * Marshals a DER integer on the output stream.
      * @param i the integer in the form of an Integer.
      */
     public void putInteger(Integer i) throws IOException {
         putInteger(i.intValue());
     }
 
     /**
      * Marshals a DER integer on the output stream.
      * @param i the integer.
      */
     public void putInteger(int i) throws IOException {
         write(DerValue.tag_Integer);
         putIntegerContents(i);
     }
 
     private void putIntegerContents(int i) throws IOException {
 
         byte[] bytes = new byte[4];
         int start = 0;
 
         // Obtain the four bytes of the int
 
         bytes[3] = (byte) (i & 0xff);
         bytes[2] = (byte)((i & 0xff00) >>> 8);
         bytes[1] = (byte)((i & 0xff0000) >>> 16);
         bytes[0] = (byte)((i & 0xff000000) >>> 24);
 
         // Reduce them to the least number of bytes needed to
         // represent this int
 
         if (bytes[0] == (byte)0xff) {
 
             // Eliminate redundant 0xff
 
             for (int j = 0; j < 3; j++) {
                 if ((bytes[j] == (byte)0xff) &&
                     ((bytes[j+1] & 0x80) == 0x80))
                     start++;
                 else
                     break;
              }
          } else if (bytes[0] == 0x00) {
 
              // Eliminate redundant 0x00
 
             for (int j = 0; j < 3; j++) {
                 if ((bytes[j] == 0x00) &&
                     ((bytes[j+1] & 0x80) == 0))
                     start++;
                 else
                     break;
             }
         }
 
         putLength(4 - start);
         for (int k = start; k < 4; k++)
             write(bytes[k]);
     }
 
     /**
      * Marshals a DER bit string on the output stream. The bit
      * string must be byte-aligned.
      *
      * @param bits the bit string, MSB first
      */
     public void putBitString(byte[] bits) throws IOException {
         write(DerValue.tag_BitString);
         putLength(bits.length + 1);
         write(0);               // all of last octet is used
         write(bits);
     }
 
     /**
      * Marshals a DER bit string on the output stream.
      * The bit strings need not be byte-aligned.
      *
      * @param bits the bit string, MSB first
      */
     public void putUnalignedBitString(BitArray ba) throws IOException {
         byte[] bits = ba.toByteArray();
 
         write(DerValue.tag_BitString);
         putLength(bits.length + 1);
         write(bits.length*8 - ba.length()); // excess bits in last octet
         write(bits);
     }
 
     /**
      * Marshals a truncated DER bit string on the output stream.
      * The bit strings need not be byte-aligned.
      *
      * @param bits the bit string, MSB first
      */
     public void putTruncatedUnalignedBitString(BitArray ba) throws IOException {
         putUnalignedBitString(ba.truncate());
     }
 
     /**
      * DER-encodes an ASN.1 OCTET STRING value on the output stream.
      *
      * @param octets the octet string
      */
     public void putOctetString(byte[] octets) throws IOException {
         write(DerValue.tag_OctetString, octets);
     }
 
     /**
      * Marshals a DER "null" value on the output stream.  These are
      * often used to indicate optional values which have been omitted.
      */
     public void putNull() throws IOException {
         write(DerValue.tag_Null);
         putLength(0);
     }
 
     /**
      * Marshals an object identifier (OID) on the output stream.
      * Corresponds to the ASN.1 "OBJECT IDENTIFIER" construct.
      */
     public void putOID(ObjectIdentifier oid) throws IOException {
         oid.encode(this);
     }
 
     /**
      * Marshals a sequence on the output stream.  This supports both
      * the ASN.1 "SEQUENCE" (zero to N values) and "SEQUENCE OF"
      * (one to N values) constructs.
      */
     public void putSequence(DerValue[] seq) throws IOException {
         DerOutputStream bytes = new DerOutputStream();
         int i;
 
         for (i = 0; i < seq.length; i++)
             seq[i].encode(bytes);
 
         write(DerValue.tag_Sequence, bytes);
     }
 
     /**
      * Marshals the contents of a set on the output stream without
      * ordering the elements.  Ok for BER encoding, but not for DER
      * encoding.
      *
      * For DER encoding, use orderedPutSet() or orderedPutSetOf().
      */
     public void putSet(DerValue[] set) throws IOException {
         DerOutputStream bytes = new DerOutputStream();
         int i;
 
         for (i = 0; i < set.length; i++)
             set[i].encode(bytes);
 
         write(DerValue.tag_Set, bytes);
     }
 
     /**
      * Marshals the contents of a set on the output stream.  Sets
      * are semantically unordered, but DER requires that encodings of
      * set elements be sorted into ascending lexicographical order
      * before being output.  Hence sets with the same tags and
      * elements have the same DER encoding.
      *
      * This method supports the ASN.1 "SET OF" construct, but not
      * "SET", which uses a different order.
      */
     public void putOrderedSetOf(byte tag, DerEncoder[] set) throws IOException {
         putOrderedSet(tag, set, lexOrder);
     }
 
     /**
      * Marshals the contents of a set on the output stream.  Sets
      * are semantically unordered, but DER requires that encodings of
      * set elements be sorted into ascending tag order
      * before being output.  Hence sets with the same tags and
      * elements have the same DER encoding.
      *
      * This method supports the ASN.1 "SET" construct, but not
      * "SET OF", which uses a different order.
      */
     public void putOrderedSet(byte tag, DerEncoder[] set) throws IOException {
         putOrderedSet(tag, set, tagOrder);
     }
 
     /**
      *  Lexicographical order comparison on byte arrays, for ordering
      *  elements of a SET OF objects in DER encoding.
      */
     private static ByteArrayLexOrder lexOrder = new ByteArrayLexOrder();
 
     /**
      *  Tag order comparison on byte arrays, for ordering elements of
      *  SET objects in DER encoding.
      */
     private static ByteArrayTagOrder tagOrder = new ByteArrayTagOrder();
 
     /**
      * Marshals a the contents of a set on the output stream with the
      * encodings of its sorted in increasing order.
      *
      * @param order the order to use when sorting encodings of components.
      */
     private void putOrderedSet(byte tag, DerEncoder[] set,
                                Comparator<byte[]> order) throws IOException {
         DerOutputStream[] streams = new DerOutputStream[set.length];
 
         for (int i = 0; i < set.length; i++) {
             streams[i] = new DerOutputStream();
             set[i].derEncode(streams[i]);
         }
 
         // order the element encodings
         byte[][] bufs = new byte[streams.length][];
         for (int i = 0; i < streams.length; i++) {
             bufs[i] = streams[i].toByteArray();
         }
         Arrays.<byte[]>sort(bufs, order);
 
         DerOutputStream bytes = new DerOutputStream();
         for (int i = 0; i < streams.length; i++) {
             bytes.write(bufs[i]);
         }
         write(tag, bytes);
 
     }
 
     /**
      * Marshals a string as a DER encoded UTF8String.
      */
     public void putUTF8String(String s) throws IOException {
         writeString(s, DerValue.tag_UTF8String, "UTF8");
     }
 
     /**
      * Marshals a string as a DER encoded PrintableString.
      */
     public void putPrintableString(String s) throws IOException {
         writeString(s, DerValue.tag_PrintableString, "ASCII");
     }
 
     /**
      * Marshals a string as a DER encoded T61String.
      */
     public void putT61String(String s) throws IOException {
         /*
          * Works for characters that are defined in both ASCII and
          * T61.
          */
         writeString(s, DerValue.tag_T61String, "ISO-8859-1");
     }
 
     /**
      * Marshals a string as a DER encoded IA5String.
      */
     public void putIA5String(String s) throws IOException {
         writeString(s, DerValue.tag_IA5String, "ASCII");
     }
 
     /**
      * Marshals a string as a DER encoded BMPString.
      */
     public void putBMPString(String s) throws IOException {
         writeString(s, DerValue.tag_BMPString, "UnicodeBigUnmarked");
     }
 
     /**
      * Marshals a string as a DER encoded GeneralString.
      */
     public void putGeneralString(String s) throws IOException {
         writeString(s, DerValue.tag_GeneralString, "ASCII");
     }
 
     /**
      * Private helper routine for writing DER encoded string values.
      * @param s the string to write
      * @param stringTag one of the DER string tags that indicate which
      * encoding should be used to write the string out.
      * @param enc the name of the encoder that should be used corresponding
      * to the above tag.
      */
     private void writeString(String s, byte stringTag, String enc)
         throws IOException {
 
         byte[] data = s.getBytes(enc);
         write(stringTag);
         putLength(data.length);
         write(data);
     }
 
     /**
      * Marshals a DER UTC time/date value.
      *
      * <P>YYMMDDhhmmss{Z|+hhmm|-hhmm} ... emits only using Zulu time
      * and with seconds (even if seconds=0) as per RFC 3280.
      */
     public void putUTCTime(Date d) throws IOException {
         putTime(d, DerValue.tag_UtcTime);
     }
 
     /**
      * Marshals a DER Generalized Time/date value.
      *
      * <P>YYYYMMDDhhmmss{Z|+hhmm|-hhmm} ... emits only using Zulu time
      * and with seconds (even if seconds=0) as per RFC 3280.
      */
     public void putGeneralizedTime(Date d) throws IOException {
         putTime(d, DerValue.tag_GeneralizedTime);
     }
 
     /**
      * Private helper routine for marshalling a DER UTC/Generalized
      * time/date value. If the tag specified is not that for UTC Time
      * then it defaults to Generalized Time.
      * @param d the date to be marshalled
      * @param tag the tag for UTC Time or Generalized Time
      */
     private void putTime(Date d, byte tag) throws IOException {
 
         /*
          * Format the date.
          */
 
         TimeZone tz = TimeZone.getTimeZone("GMT");
         String pattern = null;
 
         if (tag == DerValue.tag_UtcTime) {
             pattern = "yyMMddHHmmss'Z'";
         } else {
             tag = DerValue.tag_GeneralizedTime;
             pattern = "yyyyMMddHHmmss'Z'";
         }
 
         SimpleDateFormat sdf = new SimpleDateFormat(pattern, Locale.US);
         sdf.setTimeZone(tz);
         byte[] time = (sdf.format(d)).getBytes("ISO-8859-1");
 
         /*
          * Write the formatted date.
          */
 
         write(tag);
         putLength(time.length);
         write(time);
     }
 
     /**
      * Put the encoding of the length in the stream.
      *
      * @params len the length of the attribute.
      * @exception IOException on writing errors.
      */
     public void putLength(int len) throws IOException {
         if (len < 128) {
             write((byte)len);
 
         } else if (len < (1 << 8)) {
             write((byte)0x081);
             write((byte)len);
 
         } else if (len < (1 << 16)) {
             write((byte)0x082);
             write((byte)(len >> 8));
             write((byte)len);
 
         } else if (len < (1 << 24)) {
             write((byte)0x083);
             write((byte)(len >> 16));
             write((byte)(len >> 8));
             write((byte)len);
 
         } else {
             write((byte)0x084);
             write((byte)(len >> 24));
             write((byte)(len >> 16));
             write((byte)(len >> 8));
             write((byte)len);
         }
     }
 
     /**
      * Put the tag of the attribute in the stream.
      *
      * @params class the tag class type, one of UNIVERSAL, CONTEXT,
      *                            APPLICATION or PRIVATE
      * @params form if true, the value is constructed, otherwise it is
      * primitive.
      * @params val the tag value
      */
     public void putTag(byte tagClass, boolean form, byte val) {
         byte tag = (byte)(tagClass | val);
         if (form) {
             tag |= (byte)0x20;
         }
         write(tag);
     }
 
     /**
      *  Write the current contents of this <code>DerOutputStream</code>
      *  to an <code>OutputStream</code>.
      *
      *  @exception IOException on output error.
      */
     public void derEncode(OutputStream out) throws IOException {
         out.write(toByteArray());
     }
 }