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view libtomcrypt/src/misc/base64/base64_decode.c @ 1857:6022df862942

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Use DSCP for IP QoS traffic classes The previous TOS values are deprecated and not used by modern traffic classifiers. This sets AF21 for "interactive" traffic (with a tty). Non-tty traffic sets AF11 - that indicates high throughput but is not lowest priority (which would be CS1 or LE). This differs from the CS1 used by OpenSSH, it lets interactive git over SSH have higher priority than background least effort traffic. Dropbear's settings here should be suitable with the diffservs used by CAKE qdisc.
author Matt Johnston <matt@ucc.asn.au>
date Tue, 25 Jan 2022 17:32:20 +0800
parents d885a77b98e0
children
line wrap: on
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
 *
 * LibTomCrypt is a library that provides various cryptographic
 * algorithms in a highly modular and flexible manner.
 *
 * The library is free for all purposes without any express
 * guarantee it works.
 */
#include "tomcrypt.h"

/**
  @file base64_decode.c
  Compliant base64 code donated by Wayne Scott ([email protected])
  base64 URL Safe variant (RFC 4648 section 5) by Karel Miko
*/


#if defined(LTC_BASE64) || defined (LTC_BASE64_URL)

#if defined(LTC_BASE64)
static const unsigned char map_base64[256] = {
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255,  62, 255, 255, 255,  63,
 52,  53,  54,  55,  56,  57,  58,  59,  60,  61, 255, 255,
255, 254, 255, 255, 255,   0,   1,   2,   3,   4,   5,   6,
  7,   8,   9,  10,  11,  12,  13,  14,  15,  16,  17,  18,
 19,  20,  21,  22,  23,  24,  25, 255, 255, 255, 255, 255,
255,  26,  27,  28,  29,  30,  31,  32,  33,  34,  35,  36,
 37,  38,  39,  40,  41,  42,  43,  44,  45,  46,  47,  48,
 49,  50,  51, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255 };
#endif /* LTC_BASE64 */

#if defined(LTC_BASE64_URL)
static const unsigned char map_base64url[] = {
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255,  62, 255, 255,
 52,  53,  54,  55,  56,  57,  58,  59,  60,  61, 255, 255,
255, 254, 255, 255, 255,   0,   1,   2,   3,   4,   5,   6,
  7,   8,   9,  10,  11,  12,  13,  14,  15,  16,  17,  18,
 19,  20,  21,  22,  23,  24,  25, 255, 255, 255, 255,  63,
255,  26,  27,  28,  29,  30,  31,  32,  33,  34,  35,  36,
 37,  38,  39,  40,  41,  42,  43,  44,  45,  46,  47,  48,
 49,  50,  51, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255,
255, 255, 255, 255
};
#endif /* LTC_BASE64_URL */

enum {
   relaxed = 0,
   strict = 1
};

static int _base64_decode_internal(const unsigned char *in,  unsigned long inlen,
                                 unsigned char *out, unsigned long *outlen,
                           const unsigned char *map, int is_strict)
{
   unsigned long t, x, y, z;
   unsigned char c;
   int           g;

   LTC_ARGCHK(in     != NULL);
   LTC_ARGCHK(out    != NULL);
   LTC_ARGCHK(outlen != NULL);

   g = 0; /* '=' counter */
   for (x = y = z = t = 0; x < inlen; x++) {
       c = map[in[x]&0xFF];
       if (c == 254) {
          g++;
          continue;
       }
       else if (is_strict && g > 0) {
          /* we only allow '=' to be at the end */
          return CRYPT_INVALID_PACKET;
       }
       if (c == 255) {
          if (is_strict)
             return CRYPT_INVALID_PACKET;
          else
             continue;
       }

       t = (t<<6)|c;

       if (++y == 4) {
          if (z + 3 > *outlen) return CRYPT_BUFFER_OVERFLOW;
          out[z++] = (unsigned char)((t>>16)&255);
          out[z++] = (unsigned char)((t>>8)&255);
          out[z++] = (unsigned char)(t&255);
          y = t = 0;
       }
   }

   if (y != 0) {
      int allow_b64url = 0;
#ifdef LTC_BASE64_URL
      if (map == map_base64url) {
        allow_b64url = 1;
      }
#endif
      if (y == 1) return CRYPT_INVALID_PACKET;
      if ((y + g) != 4 && is_strict && !allow_b64url) return CRYPT_INVALID_PACKET;
      t = t << (6 * (4 - y));
      if (z + y - 1 > *outlen) return CRYPT_BUFFER_OVERFLOW;
      if (y >= 2) out[z++] = (unsigned char) ((t >> 16) & 255);
      if (y == 3) out[z++] = (unsigned char) ((t >> 8) & 255);
   }
   *outlen = z;
   return CRYPT_OK;
}

#if defined(LTC_BASE64)
/**
   Relaxed base64 decode a block of memory
   @param in       The base64 data to decode
   @param inlen    The length of the base64 data
   @param out      [out] The destination of the binary decoded data
   @param outlen   [in/out] The max size and resulting size of the decoded data
   @return CRYPT_OK if successful
*/
int base64_decode(const unsigned char *in,  unsigned long inlen,
                        unsigned char *out, unsigned long *outlen)
{
    return _base64_decode_internal(in, inlen, out, outlen, map_base64, relaxed);
}

/**
   Strict base64 decode a block of memory
   @param in       The base64 data to decode
   @param inlen    The length of the base64 data
   @param out      [out] The destination of the binary decoded data
   @param outlen   [in/out] The max size and resulting size of the decoded data
   @return CRYPT_OK if successful
*/
int base64_strict_decode(const unsigned char *in,  unsigned long inlen,
                        unsigned char *out, unsigned long *outlen)
{
   return _base64_decode_internal(in, inlen, out, outlen, map_base64, strict);
}
#endif /* LTC_BASE64 */

#if defined(LTC_BASE64_URL)
/**
   Relaxed base64 (URL Safe, RFC 4648 section 5) decode a block of memory
   @param in       The base64 data to decode
   @param inlen    The length of the base64 data
   @param out      [out] The destination of the binary decoded data
   @param outlen   [in/out] The max size and resulting size of the decoded data
   @return CRYPT_OK if successful
*/
int base64url_decode(const unsigned char *in,  unsigned long inlen,
                           unsigned char *out, unsigned long *outlen)
{
    return _base64_decode_internal(in, inlen, out, outlen, map_base64url, relaxed);
}

/**
   Strict base64 (URL Safe, RFC 4648 section 5) decode a block of memory
   @param in       The base64 data to decode
   @param inlen    The length of the base64 data
   @param out      [out] The destination of the binary decoded data
   @param outlen   [in/out] The max size and resulting size of the decoded data
   @return CRYPT_OK if successful
*/
int base64url_strict_decode(const unsigned char *in,  unsigned long inlen,
                           unsigned char *out, unsigned long *outlen)
{
    return _base64_decode_internal(in, inlen, out, outlen, map_base64url, strict);
}
#endif /* LTC_BASE64_URL */

#endif


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