asn_bits.c

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/*
 * asn_bits.c - BER encode, decode, print and free routines for ASN.1 
 *              BIT STRING type
 *
 * MS 92
 * Copyright (C) 1992 Michael Sample and the University of British Columbia
 *
 * This library is free software; you can redistribute it and/or
 * modify it provided that this copyright/license information is retained
 * in original form.
 *
 * If you modify this file, you must clearly indicate your changes.
 *
 * This source 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.
 * 
 */

#if HAVE_CONFIG_H
#include <config.h>
#endif

#include "asn_config.h"
#include "asn_len.h"
#include "asn_tag.h"
#include "str_stk.h"
#include "asn_bits.h"

static unsigned short int unusedBitsG;

char numToHexCharTblG[16] = 
    { '0', '1', '2', '3', '4', '5', '6', '7', 
      '8', '9', 'a', 'b', 'c', 'd' ,'e', 'f'};



/*
 * encodes universal TAG LENGTH and Contents of and ASN.1 BIT STRING
 */
AsnLen
BEncAsnBits PARAMS((b, data),
BUF_TYPE     b _AND_
AsnBits* data)
{
    AsnLen len;

    len =  BEncAsnBitsContent(b, data);
    len += BEncDefLen(b, len);
    len += BEncTag1(b, UNIV, PRIM, BITSTRING_TAG_CODE);
    return(len);
}  /* BEncAsnInt */


/* 
 * decodes universal TAG LENGTH and Contents of and ASN.1 BIT STRING
 */
void
BDecAsnBits PARAMS((b, result, bytesDecoded, env),
BUF_TYPE   b _AND_
AsnBits*    result _AND_
AsnLen* bytesDecoded _AND_
jmp_buf env)
{
    AsnTag tag;
    AsnLen elmtLen;

    if (((tag =BDecTag(b, bytesDecoded, env)) !=
         MAKE_TAG_ID(UNIV, PRIM, BITSTRING_TAG_CODE)) &&
        (tag != MAKE_TAG_ID(UNIV, CONS, BITSTRING_TAG_CODE)))
    {
         Asn1Error("BDecAsnBits: ERROR - wrong tag on BIT STRING.\n");
         longjmp(env, -40);
    }

    elmtLen = BDecLen (b, bytesDecoded, env);
    BDecAsnBitsContent( b, tag, elmtLen, result, bytesDecoded, env);

}  /* BDecAsnBits */



/*
 * Encodes the BIT STRING value (including the unused bits
 * byte) to the given buffer.
 */
AsnLen
BEncAsnBitsContent PARAMS((b, bits),
BUF_TYPE b _AND_
AsnBits* bits)
{
    unsigned long int unusedBits;
    unsigned long int byteLen;

    if (bits->bitLen == 0)
        byteLen = 0;
    else
        byteLen = ((bits->bitLen-1) / 8) + 1;

    BufPutSegRvs(b, bits->bits, byteLen);
    unusedBits = (bits->bitLen % 8);
    if (unusedBits != 0)
        unusedBits = 8 - unusedBits;
    BufPutByteRvs(b, unusedBits);
    return(byteLen + 1);

} /* BEncAsnBitsContent */


/*
 * Used when decoding to combine constructed pieces into one
 * contiguous block.
 * Fills string stack with references to the pieces of a
 * construced bit string. sets unusedBitsG appropriately.
 * and strStkG.totalByteLenG to bytelen needed to hold the bitstring
 */
static void
FillBitStringStk PARAMS((b, elmtLen0, bytesDecoded, env),
BUF_TYPE b _AND_
AsnLen elmtLen0 _AND_
AsnLen* bytesDecoded _AND_
jmp_buf env)
{
    unsigned long int refdLen;
    unsigned long int totalRefdLen;
    char* strPtr;
    unsigned long int totalElmtsLen1 = 0;
    unsigned long int tagId1;
    unsigned long int elmtLen1;
    unsigned long int lenToRef;
    unsigned long int unusedBits;

    for ( ; (totalElmtsLen1 < elmtLen0) || (elmtLen0 == INDEFINITE_LEN);)
    {
        tagId1 = BDecTag(b, &totalElmtsLen1, env);

        if ( (tagId1 == EOC_TAG_ID) && (elmtLen0 == INDEFINITE_LEN))
        {
            BDEC_2ND_EOC_OCTET(b, &totalElmtsLen1, env);
            break; 
        }

        elmtLen1 = BDecLen (b, &totalElmtsLen1, env);
        if ( tagId1 == MAKE_TAG_ID( UNIV, PRIM, BITSTRING_TAG_CODE))
        {
            /*
             * primitive part of string, put references to piece(s) in
             * str stack
             */

            /*
             * get unused bits octet 
             */
            if (unusedBitsG != 0)
            {
                /*  
                 *  whoa - only allowed non-octet aligned bits on
                 *  on last piece of bits string
                 */
                Asn1Error("FillBitStringStk: ERROR - a component of a constructed BIT STRING that is not the last has non-zero unused bits\n");
                longjmp(env, -1);
            }

            if (elmtLen1 != 0)
                unusedBitsG = BufGetByte(b);

            totalRefdLen = 0;
            lenToRef =elmtLen1-1; /* remove one octet for the unused bits oct*/
            refdLen = lenToRef;
            while (1)
            {
                strPtr = BufGetSeg( b, &refdLen);

                PUSH_STR(strPtr, refdLen, env);
                totalRefdLen += refdLen;
                if (totalRefdLen == lenToRef)
                    break; /* exit this while loop */

                if (refdLen == 0) /* end of data */
                {
                    Asn1Error("FillBitStringStk: ERROR - expecting more data\n");
                    longjmp(env, -2);
                }
                refdLen = lenToRef - totalRefdLen;
            }
            totalElmtsLen1 += elmtLen1;
        } 

    
        else if ( tagId1 == MAKE_TAG_ID( UNIV, CONS, BITSTRING_TAG_CODE))
        {
            /*
             * constructed octets string embedding in this constructed
             * octet string. decode it.
             */
            FillBitStringStk( b, elmtLen1, &totalElmtsLen1, env);
        }
        else  /* wrong tag */
        {
            Asn1Error("FillBitStringStk: ERROR - decoded non-BIT STRING tag inside a constructed BIT STRING\n");
            longjmp(env, -3);
        }
    } /* end of for */

    (*bytesDecoded) += totalElmtsLen1;

}  /* FillBitStringStk */


/*
 * Decodes a seq of universally tagged bits until either EOC is 
 * encountered or the given len decoded.  Returns them in a
 * single concatenated bit string
 */
static void
BDecConsAsnBits PARAMS((b, len, result, bytesDecoded, env),
BUF_TYPE b _AND_
AsnLen len _AND_
AsnBits* result _AND_
AsnLen* bytesDecoded _AND_
jmp_buf env)
{
    char* bufCurr;
    unsigned long int curr;

    RESET_STR_STK();
        
    /*
     * decode each piece of the octet string, puting
     * an entry in the octet/bit string stack for each 
     */
    FillBitStringStk(b, len, bytesDecoded, env);
    
    /* alloc single str long enough for combined bitstring */
    result->bitLen = strStkG.totalByteLen*8 - unusedBitsG;

    bufCurr = result->bits = Asn1Alloc(strStkG.totalByteLen); 

    /* copy bit string pieces (buffer refs) into single block */
    for (curr = 0; curr < strStkG.nextFreeElmt; curr++)
    {
        memcpy(bufCurr, strStkG.stk[curr].str, strStkG.stk[curr].len);
        bufCurr += strStkG.stk[curr].len;
    }

}  /* BDecConsAsnBits */

/*
 * Decodes the content of a BIT STRING (including the unused bits octet)
 * Always returns a single contiguous bit string
 */
void
BDecAsnBitsContent PARAMS((b, tagId, len, result, bytesDecoded, env),
BUF_TYPE b _AND_
AsnTag tagId _AND_
AsnLen len _AND_
AsnBits* result _AND_
AsnLen* bytesDecoded _AND_
jmp_buf env)
{
    char* tmp;

    /*
     * tagId is encoded tag shifted into long int.
     * if CONS bit is set then constructed bit string
     */
    if (TAG_IS_CONS(tagId))
        BDecConsAsnBits(b, len, result, bytesDecoded, env);

    else /* primitive octet string */
    {
        (*bytesDecoded) += len;
        len--;
        result->bitLen = (len * 8) - (unsigned int)BufGetByte(b);
        result->bits =  Asn1Alloc(len);
        BufCopy( result->bits, b, len);
        if (BufReadError(b))
        {
            Asn1Error("BDecAsnBitsContent: ERROR - decoded past end of data\n");
            longjmp(env, -4);
        }
    }

}  /* BDecAsnBitsContent */



/*
 * Frees the string part of a BIT STRING
 */
void
FreeAsnBits PARAMS((v),
AsnBits* v)
{
    Asn1Free(v->bits);
} /* FreeAsnBits  */


/*
 * Prints the contents of the given BIT STRING to the 
 * given file. indent is ignored.  Always uses ASN.1 Value Notaion
 * Hex format. (Should be binary versions in some cases)
 */
void
PrintAsnBits PARAMS((f,v, indent),
FILE* f _AND_
AsnBits* v _AND_
unsigned short indent)
{
    int i;
    unsigned long int octetLen;

    if (v->bitLen == 0)
        octetLen = 0;
    else
        octetLen = (v->bitLen-1)/8 +1;

    fprintf(f,"'");
    for(i = 0; i < octetLen; i++)
        fprintf(f,"%c%c", TO_HEX(v->bits[i] >> 4), TO_HEX(v->bits[i]));
    fprintf(f,"'H");

} /* PrintAsnBits  */

/*
 * Returns TRUE if the given BIT STRINGs are identical.
 * Otherwise returns FALSE.
 */
int
AsnBitsEquiv PARAMS((b1, b2),
AsnBits* b1 _AND_
AsnBits* b2)
{
    int octetsLessOne;
    int octetBits;

    if ((b1->bitLen == 0) && (b2->bitLen == 0))
        return(TRUE);

    octetsLessOne = (b1->bitLen-1)/8;
    octetBits = 7 - (b1->bitLen % 8);

    /* trailing bits may not be significant  */
    return ( (b1->bitLen == b2->bitLen) &&
             (memcmp(b1->bits, b2->bits, octetsLessOne) == 0) &&
             (( b1->bits[octetsLessOne] & (0xFF << octetBits)) ==
              ( b1->bits[octetsLessOne] & (0xFF << octetBits))));

} /* AsnBitsEquiv */


/*
 * Set given bit to 1.  Most significant bit is bit 0, least significant
 * is bit (v1->bitLen -1)
 */
void
SetAsnBit PARAMS((b1, bit),
AsnBits* b1 _AND_
unsigned long int bit)
{
    unsigned long int octet;
    unsigned long int octetsBit;

    if (bit < b1->bitLen)
    {
        octet = bit/8;
        octetsBit = 7 - (bit % 8);/* bit zero is first/most sig bit in octet */
        b1->bits[octet] |= 1 << octetsBit;
    }
}  /* SetAsnBit */


/*
 * Set given bit to 0.  Most significant bit is bit 0, least significant
 * is bit (v1->bitLen -1)
 */
void
ClrAsnBit PARAMS((b1, bit),
AsnBits* b1 _AND_
unsigned long int bit)
{
    unsigned long int octet;
    unsigned long int octetsBit;

    if (bit <  b1->bitLen)
    {
        octet = bit/8;
        octetsBit = 7 - (bit % 8);/* bit zero is first/most sig bit in octet */
        b1->bits[octet] &= ~(1 << octetsBit);
    }

}  /* ClrAsnBit */


/*
 * Get given bit.  Most significant bit is bit 0, least significant
 * is bit (v1->bitLen -1).  Returns TRUE if the bit is 1. Returns FALSE
 * if the bit is 0.  if the bit is out of range then returns 0.
 */
int
GetAsnBit PARAMS((b1, bit),
AsnBits* b1 _AND_
unsigned long int bit)
{
    unsigned long int octet;
    unsigned long int octetsBit;

    if (bit < b1->bitLen)
    {
        octet = bit/8;
        octetsBit = 7 - (bit % 8); /* bit zero is first/most sig bit in octet*/
        return (b1->bits[octet] & (1 << octetsBit));
    }
    return(0);    
}  /* AsnBits::GetBit */