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base64.c

/*
 * base64.c: Base64 converting functions
 *
 * Copyright (C) 2001, 2002  Juha Yrjölä <juha.yrjola@iki.fi>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#define __BASE64_C_

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <assert.h>

#include "debug.h"
#include "error.h"
#include "base64.h"

static const unsigned char codes[66] =
    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";

static const unsigned char bin_table[128] = {
      0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
      0xFF, 0xE0, 0xD0, 0xFF, 0xFF, 0xD0, 0xFF, 0xFF,
      0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
      0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
      0xE0, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
      0xFF, 0xFF, 0xFF, 0x3E, 0xFF, 0xF2, 0xFF, 0x3F,
      0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3A, 0x3B,
      0x3C, 0x3D, 0xFF, 0xFF, 0xFF, 0xC0, 0xFF, 0xFF,
      0xFF, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,
      0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0x0D, 0x0E,
      0x0F, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16,
      0x17, 0x18, 0x19, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
      0xFF, 0x1A, 0x1B, 0x1C, 0x1D, 0x1E, 0x1F, 0x20,
      0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28,
      0x29, 0x2A, 0x2B, 0x2C, 0x2D, 0x2E, 0x2F, 0x30,
      0x31, 0x32, 0x33, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
};

static int from_base64(const char *in, unsigned int *out, int *skip) {
      unsigned int res = 0, c, s = 18;
      const char *in0 = in;

      for (c = 0; c < 4; c++, in++) {
            unsigned char b;
            int k = *in;

            if (k < 0) return -1;
            if (k == 0 && c == 0) return 0;
            b = bin_table[k];
            if (b == 0xC0)    /* '=' */ break;
            switch (b) {
            case 0xD0:  /* '\n' or '\r' */
                  c--;
                  continue;
            }
            if (b > 0x3f) return -1;

            res |= b << s;
            s -= 6;
      }
      *skip = in - in0;
      *out = res;
      return c * 6 / 8;
}

int base64_encode(const unsigned char *in,  size_t len, unsigned char *out, size_t *outlen) {
   size_t i, len2, leven;
   unsigned char *p;

   if (!in) return -1;
   if (!out) return -1;
   if (!outlen) return -1;

   /* valid output size ? */
   len2 = 4 * ((len + 2) / 3);
   if (*outlen < len2 + 1) {
      DBG3("Not enought space '%d' to process '%d': needed '%d' bytes",*outlen,len,len2+1);
      return -1;
            }
   p = out;
   leven = 3*(len / 3);
   for (i = 0; i < leven; i += 3) {
       *p++ = codes[(in[0] >> 2) & 0x3F];
       *p++ = codes[(((in[0] & 3) << 4) + (in[1] >> 4)) & 0x3F];
       *p++ = codes[(((in[1] & 0xf) << 2) + (in[2] >> 6)) & 0x3F];
       *p++ = codes[in[2] & 0x3F];
       in += 3;
      }
   /* Pad it if necessary...  */
   if (i < len) {
       unsigned a = in[0];
       unsigned b = (i+1 < len) ? in[1] : 0;
       *p++ = codes[(a >> 2) & 0x3F];
       *p++ = codes[(((a & 3) << 4) + (b >> 4)) & 0x3F];
       *p++ = (i+1 < len) ? codes[(((b & 0xf) << 2)) & 0x3F] : '=';
       *p++ = '=';
      }

   /* append a NULL byte */
   *p = '\0';

   /* return ok */
   *outlen = p - out;
      return 0;
}

int base64_decode(const char *in, unsigned char *out, size_t outlen) {
      int len = 0, r, skip;
      unsigned int i;

      while ((r = from_base64(in, &i, &skip)) > 0) {
            int finished = 0, s = 16;

            if (r < 3) finished = 1;
            while (r--) {
                  if (outlen <= 0) return -1;
                  *out++ = i >> s;
                  s -= 8;
                  outlen--;
                  len++;
            }
            in += skip;
            if (finished || *in == 0) return len;
      }
      if (r == 0) return len;
      return -1;
}

#undef __BASE64_C_

/* end of file */

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