SecuritySNACCRuntime/c++-lib/c++/asn-len.cpp

   1 /*
   2  * Copyright (c) 2000-2001 Apple Computer, Inc. All Rights Reserved.
   3  *
   4  * The contents of this file constitute Original Code as defined in and are
   5  * subject to the Apple Public Source License Version 1.2 (the 'License').
   6  * You may not use this file except in compliance with the License. Please obtain
   7  * a copy of the License at http://www.apple.com/publicsource and read it before
   8  * using this file.
   9  *
  10  * This Original Code and all software distributed under the License are
  11  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS
  12  * OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, INCLUDING WITHOUT
  13  * LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
  14  * PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. Please see the License for the
  15  * specific language governing rights and limitations under the License.
  16  */
  17
  18
  19 // file: .../c++-lib/src/asn-len.C - ASN.1 Length manipluation routines
  20 //
  21 // MS 92/06/18
  22 // Copyright (C) 1992 Michael Sample and the University of British Columbia
  23 //
  24 // This library is free software; you can redistribute it and/or
  25 // modify it provided that this copyright/license information is retained
  26 // in original form.
  27 //
  28 // If you modify this file, you must clearly indicate your changes.
  29 //
  30 // This source code is distributed in the hope that it will be
  31 // useful, but WITHOUT ANY WARRANTY; without even the implied warranty
  32 // of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  33 //
  34
  35 #include "asn-config.h"
  36 #include "asn-len.h"
  37
  38
  39 /*
  40  * Encodes the given length to the given buffer.
  41  * returns the number of octets written to the buffer.
  42  */
  43 AsnLen
  44 BEncDefLen (BUF_TYPE  b, AsnLen len)
  45 {
  46     /*
  47      * unrolled for efficiency
  48      * (check each possibitlity of the 4 byte integer)
  49      */
  50     if (len < 128)
  51     {
  52         b.PutByteRvs (len);
  53         return 1;
  54     }
  55     else if (len < 256)
  56     {
  57         b.PutByteRvs (len);
  58         b.PutByteRvs (0x81);
  59         return 2;
  60     }
  61     else if (len < 65536)
  62     {
  63         b.PutByteRvs (len);
  64         b.PutByteRvs (len >> 8);
  65         b.PutByteRvs (0x82);
  66         return 3;
  67     }
  68     else if (len < 16777126)
  69     {
  70         b.PutByteRvs (len);
  71         b.PutByteRvs (len >> 8);
  72         b.PutByteRvs (len >> 16);
  73         b.PutByteRvs (0x83);
  74         return 4;
  75     }
  76     else
  77     {
  78         b.PutByteRvs (len);
  79         b.PutByteRvs (len >> 8);
  80         b.PutByteRvs (len >> 16);
  81         b.PutByteRvs (len >> 24);
  82         b.PutByteRvs (0x84);
  83         return 5;
  84     }
  85 } /*  EncodeDefLen */
  86
  87 /*
  88  * Decode a BER length from the given buffer. Increments bytesDecoded
  89  * by the number of octets of the encoded length.  Flags an
  90  * error if the length is too large or a read error occurs
  91  */
  92 AsnLen
  93 BDecLen (BUF_TYPE b, AsnLen &bytesDecoded, ENV_TYPE env)
  94 {
  95     AsnLen  len;
  96     unsigned char  byte;
  97     unsigned  lenBytes;
  98
  99     byte = b.GetByte();
 100
 101     if (b.ReadError())
 102     {
 103         Asn1Error << "BDecLen: decoded past end of data" << endl;
 104                 #if SNACC_EXCEPTION_ENABLE
 105                 SnaccExcep::throwMe(-9);
 106                 #else
 107         longjmp (env, -9);
 108                 #endif
 109     }
 110
 111     bytesDecoded++;
 112     if (byte < 128)   /* short length */
 113         return byte;
 114
 115     else if (byte == (unsigned char) 0x080)  /* indef len indicator */
 116         return INDEFINITE_LEN;
 117
 118     else  /* long len form */
 119     {
 120         /*
 121          * strip high bit to get # bytes left in len
 122          */
 123         lenBytes = byte & (unsigned char) 0x7f;
 124
 125         if (lenBytes > sizeof (long int))
 126         {
 127             Asn1Error << "BDecLen: ERROR - length overflow" << endl;
 128                         #if SNACC_EXCEPTION_ENABLE
 129                         SnaccExcep::throwMe(-10);
 130                         #else
 131             longjmp (env, -10);
 132                         #endif
 133         }
 134
 135         bytesDecoded += lenBytes;
 136
 137         for (len = 0; lenBytes > 0; lenBytes--)
 138             len = (len << 8) | (unsigned long int) b.GetByte();
 139
 140
 141         if (b.ReadError())
 142         {
 143             Asn1Error << "BDecLen: decoded past end of data" << endl;
 144                         #if SNACC_EXCEPTION_ENABLE
 145                         SnaccExcep::throwMe(-11);
 146                         #else
 147             longjmp (env, -11);
 148                         #endif
 149         }
 150
 151         return len;
 152     }
 153     /* not reached */
 154 }
 155
 156
 157 /*
 158  * Encodes an End of Contents (EOC) to the given buffer.
 159  * Returns the encoded length.
 160  */
 161 AsnLen
 162 BEncEoc (BUF_TYPE b)
 163 {
 164
 165     b.PutByteRvs (0);
 166     b.PutByteRvs (0);
 167     return 2;
 168 }  /* BEncEoc */
 169
 170 /*
 171  * Decodes an EOC from the given buffer.  flags an error if the
 172  * octets are non-zero or if read error occured.
 173  */
 174 void
 175 BDecEoc (BUF_TYPE b, AsnLen &bytesDecoded, ENV_TYPE env)
 176 {
 177
 178     if ((b.GetByte() != 0) || (b.GetByte() != 0) || b.ReadError())
 179     {
 180         Asn1Error << "BDecEoc: ERROR - non zero byte in EOC or end of data reached" << endl;
 181                 #if SNACC_EXCEPTION_ENABLE
 182                 SnaccExcep::throwMe(-12);
 183                 #else
 184         longjmp (env, -12);
 185                 #endif
 186     }
 187     bytesDecoded += 2;
 188 }  /* BDecEoc */