crypto/asn1/a_bitstr.c

   1 /*
   2  * Copyright 1995-2021 The OpenSSL Project Authors. All Rights Reserved.
   3  *
   4  * Licensed under the Apache License 2.0 (the "License").  You may not use
   5  * this file except in compliance with the License.  You can obtain a copy
   6  * in the file LICENSE in the source distribution or at
   7  * https://www.openssl.org/source/license.html
   8  */
   9
  10 #include <limits.h>
  11 #include <stdio.h>
  12 #include "internal/cryptlib.h"
  13 #include <openssl/asn1.h>
  14 #include "asn1_local.h"
  15
  16 int ASN1_BIT_STRING_set(ASN1_BIT_STRING *x, unsigned char *d, int len)
  17 {
  18     return ASN1_STRING_set(x, d, len);
  19 }
  20
  21 int ossl_i2c_ASN1_BIT_STRING(ASN1_BIT_STRING *a, unsigned char **pp)
  22 {
  23     int ret, j, bits, len;
  24     unsigned char *p, *d;
  25
  26     if (a == NULL)
  27         return 0;
  28
  29     len = a->length;
  30
  31     if (len > 0) {
  32         if (a->flags & ASN1_STRING_FLAG_BITS_LEFT) {
  33             bits = (int)a->flags & 0x07;
  34         } else {
  35             for (; len > 0; len--) {
  36                 if (a->data[len - 1])
  37                     break;
  38             }
  39             j = a->data[len - 1];
  40             if (j & 0x01)
  41                 bits = 0;
  42             else if (j & 0x02)
  43                 bits = 1;
  44             else if (j & 0x04)
  45                 bits = 2;
  46             else if (j & 0x08)
  47                 bits = 3;
  48             else if (j & 0x10)
  49                 bits = 4;
  50             else if (j & 0x20)
  51                 bits = 5;
  52             else if (j & 0x40)
  53                 bits = 6;
  54             else if (j & 0x80)
  55                 bits = 7;
  56             else
  57                 bits = 0;       /* should not happen */
  58         }
  59     } else
  60         bits = 0;
  61
  62     ret = 1 + len;
  63     if (pp == NULL)
  64         return ret;
  65
  66     p = *pp;
  67
  68     *(p++) = (unsigned char)bits;
  69     d = a->data;
  70     if (len > 0) {
  71         memcpy(p, d, len);
  72         p += len;
  73         p[-1] &= (0xff << bits);
  74     }
  75     *pp = p;
  76     return ret;
  77 }
  78
  79 ASN1_BIT_STRING *ossl_c2i_ASN1_BIT_STRING(ASN1_BIT_STRING **a,
  80                                           const unsigned char **pp, long len)
  81 {
  82     ASN1_BIT_STRING *ret = NULL;
  83     const unsigned char *p;
  84     unsigned char *s;
  85     int i;
  86
  87     if (len < 1) {
  88         i = ASN1_R_STRING_TOO_SHORT;
  89         goto err;
  90     }
  91
  92     if (len > INT_MAX) {
  93         i = ASN1_R_STRING_TOO_LONG;
  94         goto err;
  95     }
  96
  97     if ((a == NULL) || ((*a) == NULL)) {
  98         if ((ret = ASN1_BIT_STRING_new()) == NULL)
  99             return NULL;
 100     } else
 101         ret = (*a);
 102
 103     p = *pp;
 104     i = *(p++);
 105     if (i > 7) {
 106         i = ASN1_R_INVALID_BIT_STRING_BITS_LEFT;
 107         goto err;
 108     }
 109     /*
 110      * We do this to preserve the settings.  If we modify the settings, via
 111      * the _set_bit function, we will recalculate on output
 112      */
 113     ret->flags &= ~(ASN1_STRING_FLAG_BITS_LEFT | 0x07); /* clear */
 114     ret->flags |= (ASN1_STRING_FLAG_BITS_LEFT | i); /* set */
 115
 116     if (len-- > 1) {            /* using one because of the bits left byte */
 117         s = OPENSSL_malloc((int)len);
 118         if (s == NULL) {
 119             i = ERR_R_MALLOC_FAILURE;
 120             goto err;
 121         }
 122         memcpy(s, p, (int)len);
 123         s[len - 1] &= (0xff << i);
 124         p += len;
 125     } else
 126         s = NULL;
 127
 128     ret->length = (int)len;
 129     OPENSSL_free(ret->data);
 130     ret->data = s;
 131     ret->type = V_ASN1_BIT_STRING;
 132     if (a != NULL)
 133         (*a) = ret;
 134     *pp = p;
 135     return ret;
 136  err:
 137     ERR_raise(ERR_LIB_ASN1, i);
 138     if ((a == NULL) || (*a != ret))
 139         ASN1_BIT_STRING_free(ret);
 140     return NULL;
 141 }
 142
 143 /*
 144  * These next 2 functions from Goetz Babin-Ebell.
 145  */
 146 int ASN1_BIT_STRING_set_bit(ASN1_BIT_STRING *a, int n, int value)
 147 {
 148     int w, v, iv;
 149     unsigned char *c;
 150
 151     w = n / 8;
 152     v = 1 << (7 - (n & 0x07));
 153     iv = ~v;
 154     if (!value)
 155         v = 0;
 156
 157     if (a == NULL)
 158         return 0;
 159
 160     a->flags &= ~(ASN1_STRING_FLAG_BITS_LEFT | 0x07); /* clear, set on write */
 161
 162     if ((a->length < (w + 1)) || (a->data == NULL)) {
 163         if (!value)
 164             return 1;         /* Don't need to set */
 165         c = OPENSSL_clear_realloc(a->data, a->length, w + 1);
 166         if (c == NULL) {
 167             ERR_raise(ERR_LIB_ASN1, ERR_R_MALLOC_FAILURE);
 168             return 0;
 169         }
 170         if (w + 1 - a->length > 0)
 171             memset(c + a->length, 0, w + 1 - a->length);
 172         a->data = c;
 173         a->length = w + 1;
 174     }
 175     a->data[w] = ((a->data[w]) & iv) | v;
 176     while ((a->length > 0) && (a->data[a->length - 1] == 0))
 177         a->length--;
 178     return 1;
 179 }
 180
 181 int ASN1_BIT_STRING_get_bit(const ASN1_BIT_STRING *a, int n)
 182 {
 183     int w, v;
 184
 185     w = n / 8;
 186     v = 1 << (7 - (n & 0x07));
 187     if ((a == NULL) || (a->length < (w + 1)) || (a->data == NULL))
 188         return 0;
 189     return ((a->data[w] & v) != 0);
 190 }
 191
 192 /*
 193  * Checks if the given bit string contains only bits specified by
 194  * the flags vector. Returns 0 if there is at least one bit set in 'a'
 195  * which is not specified in 'flags', 1 otherwise.
 196  * 'len' is the length of 'flags'.
 197  */
 198 int ASN1_BIT_STRING_check(const ASN1_BIT_STRING *a,
 199                           const unsigned char *flags, int flags_len)
 200 {
 201     int i, ok;
 202     /* Check if there is one bit set at all. */
 203     if (!a || !a->data)
 204         return 1;
 205
 206     /*
 207      * Check each byte of the internal representation of the bit string.
 208      */
 209     ok = 1;
 210     for (i = 0; i < a->length && ok; ++i) {
 211         unsigned char mask = i < flags_len ? ~flags[i] : 0xff;
 212         /* We are done if there is an unneeded bit set. */
 213         ok = (a->data[i] & mask) == 0;
 214     }
 215     return ok;
 216 }