src/org/bouncycastle/asn1/BERInputStream.java

   1 package org.bouncycastle.asn1;
   2
   3 import java.math.BigInteger;
   4 import java.io.*;
   5 import java.util.*;
   6
   7 public class BERInputStream
   8     extends DERInputStream
   9 {
  10         private DERObject END_OF_STREAM = new DERObject() {
  11                                                                                 void encode(
  12                                                                                         DEROutputStream out)
  13                                                                                 throws IOException
  14                                                                                 {
  15                                                                                         throw new IOException("Eeek!");
  16                                                                                 }
  17
  18                                                                         };
  19     public BERInputStream(
  20         InputStream is)
  21     {
  22         super(is);
  23     }
  24
  25     /**
  26      * read a string of bytes representing an indefinite length object.
  27      */
  28     private byte[] readIndefiniteLengthFully()
  29         throws IOException
  30     {
  31         ByteArrayOutputStream   bOut = new ByteArrayOutputStream();
  32         int                     b, b1;
  33
  34         b1 = read();
  35
  36         while ((b = read()) >= 0)
  37         {
  38                         if (b1 == 0 && b == 0)
  39                         {
  40                                 break;
  41                         }
  42
  43             bOut.write(b1);
  44             b1 = b;
  45         }
  46
  47         return bOut.toByteArray();
  48     }
  49
  50         private BERConstructedOctetString buildConstructedOctetString(
  51                 DEROctetString  o1,
  52                 DEROctetString  o2)
  53                 throws IOException
  54         {
  55         Vector                  octs = new Vector();
  56
  57                 if (o1 != null)
  58                 {
  59             octs.addElement(o1);
  60             octs.addElement(o2);
  61                 }
  62
  63                 for (;;)
  64                 {
  65                         DERObject               o = readObject();
  66
  67                         if (o == END_OF_STREAM)
  68                         {
  69                                 break;
  70                         }
  71
  72             octs.addElement(o);
  73                 }
  74
  75                 return new BERConstructedOctetString(octs);
  76         }
  77
  78     public DERObject readObject()
  79         throws IOException
  80     {
  81         int tag = read();
  82         if (tag == -1)
  83         {
  84             throw new EOFException();
  85         }
  86
  87         int     length = readLength();
  88
  89         if (length < 0)    // indefinite length method
  90         {
  91             byte[]  bytes;
  92
  93             switch (tag)
  94             {
  95             case NULL:
  96                 return null;
  97             case SEQUENCE | CONSTRUCTED:
  98                 BERConstructedSequence  seq = new BERConstructedSequence();
  99
 100                                 for (;;)
 101                                 {
 102                                         DERObject   obj = readObject();
 103
 104                                         if (obj == END_OF_STREAM)
 105                                         {
 106                                                 break;
 107                                         }
 108
 109                                         seq.addObject(obj);
 110                                 }
 111                                 return seq;
 112             case OCTET_STRING | CONSTRUCTED:
 113                                 return buildConstructedOctetString(null, null);
 114             default:
 115                 if ((tag & (TAGGED | CONSTRUCTED)) != 0)
 116                 {
 117                                         // with tagged object tag number is bottom 4 bits
 118                     BERTaggedObject tagObj = new BERTaggedObject(tag & 0x0f, readObject());
 119                                         DERObject               o = readObject();
 120
 121                                         if (o == END_OF_STREAM)
 122                                         {
 123                                                 return tagObj;
 124                                         }
 125                                         else if (o instanceof DEROctetString
 126                                                         && tagObj.getObject() instanceof DEROctetString)
 127                                         {
 128                                                 //
 129                                                 // it's an implicit object - mark it as so...
 130                                                 //
 131                                                 tagObj = new BERTaggedObject(false, tag & 0x0f,
 132                                                                                 buildConstructedOctetString((DEROctetString)tagObj.getObject(), (DEROctetString)o));
 133
 134                                                 return tagObj;
 135                                         }
 136
 137                                         throw new IOException("truncated tagged object");
 138                 }
 139
 140                 bytes = readIndefiniteLengthFully();
 141
 142                 return buildObject(tag, bytes);
 143             }
 144         }
 145         else
 146         {
 147             if (tag == 0 && length == 0)    // end of contents marker.
 148             {
 149                 return END_OF_STREAM;
 150             }
 151
 152             byte[]  bytes = new byte[length];
 153
 154             readFully(bytes);
 155
 156                         return buildObject(tag, bytes);
 157         }
 158     }
 159 }