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base64.c

/*
 * Copyright 1998-2003 The OpenLDAP Foundation, All Rights Reserved.
 * COPYING RESTRICTIONS APPLY, see COPYRIGHT file
 */
/*
 * Copyright (c) 1996, 1998 by Internet Software Consortium.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
 * SOFTWARE.
 */
/*
 * Portions Copyright (c) 1995 by International Business Machines, Inc.
 *
 * International Business Machines, Inc. (hereinafter called IBM) grants
 * permission under its copyrights to use, copy, modify, and distribute this
 * Software with or without fee, provided that the above copyright notice and
 * all paragraphs of this notice appear in all copies, and that the name of IBM
 * not be used in connection with the marketing of any product incorporating
 * the Software or modifications thereof, without specific, written prior
 * permission.
 *
 * To the extent it has a right to do so, IBM grants an immunity from suit
 * under its patents, if any, for the use, sale or manufacture of products to
 * the extent that such products are used for performing Domain Name System
 * dynamic updates in TCP/IP networks by means of the Software.  No immunity is
 * granted for any product per se or for any other function of any product.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", AND IBM DISCLAIMS ALL WARRANTIES,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
 * PARTICULAR PURPOSE.  IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL,
 * DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER ARISING
 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE, EVEN
 * IF IBM IS APPRISED OF THE POSSIBILITY OF SUCH DAMAGES.
 */
#include <ctype.h>
#include <stdlib.h>
#include <stdio.h>
#include <assert.h>
#include "common.h"

static const char Base64[] =
      "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static const char Pad64 = '=';

void
print_base64(
      unsigned char const *src,
      size_t srclength,
      FILE *s)
{
      unsigned char input[3];
      unsigned char output[4];
      size_t i;
      int col = 0;

      while (2 < srclength) {
            input[0] = *src++;
            input[1] = *src++;
            input[2] = *src++;
            srclength -= 3;

            output[0] = input[0] >> 2;
            output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
            output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
            output[3] = input[2] & 0x3f;

            if (col >= 76) {
                  fputs("\n ", s);
                  col = 0;
            }
            col += 4;

            fputc(Base64[output[0]], s);
            fputc(Base64[output[1]], s);
            fputc(Base64[output[2]], s);
            fputc(Base64[output[3]], s);
      }
    
      /* Now we worry about padding. */
      if (0 != srclength) {
            /* Get what's left. */
            input[0] = input[1] = input[2] = '\0';
            for (i = 0; i < srclength; i++)
                  input[i] = *src++;
      
            output[0] = input[0] >> 2;
            output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
            output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);

            fputc(Base64[output[0]], s);
            fputc(Base64[output[1]], s);
            if (srclength == 1)
                  fputc(Pad64, s);
            else
                  fputc(Base64[output[2]], s);
            fputc(Pad64, s);
      }
}

/* na toll, copy und paste von oben */
void
g_string_append_base64(
      GString *string, unsigned char const *src, size_t srclength)
{
      unsigned char input[3];
      unsigned char output[4];
      size_t i;
      int col = 0;

      while (2 < srclength) {
            input[0] = *src++;
            input[1] = *src++;
            input[2] = *src++;
            srclength -= 3;

            output[0] = input[0] >> 2;
            output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
            output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
            output[3] = input[2] & 0x3f;

            if (col >= 76) {
                  g_string_append(string, "\n ");
                  col = 0;
            }
            col += 4;

            g_string_append_c(string, Base64[output[0]]);
            g_string_append_c(string, Base64[output[1]]);
            g_string_append_c(string, Base64[output[2]]);
            g_string_append_c(string, Base64[output[3]]);
      }
    
      /* Now we worry about padding. */
      if (0 != srclength) {
            /* Get what's left. */
            input[0] = input[1] = input[2] = '\0';
            for (i = 0; i < srclength; i++)
                  input[i] = *src++;
      
            output[0] = input[0] >> 2;
            output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
            output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);

            g_string_append_c(string, Base64[output[0]]);
            g_string_append_c(string, Base64[output[1]]);
            if (srclength == 1)
                  g_string_append_c(string, Pad64);
            else
                  g_string_append_c(string, Base64[output[2]]);
            g_string_append_c(string, Pad64);
      }
}

int
read_base64(
      char const *src,
      unsigned char *target, 
      size_t targsize)
{
      int tarindex, state, ch;
      char *pos;

      state = 0;
      tarindex = 0;

      while ((ch = *src++) != '\0') {
            if (isascii(ch) && isspace(ch))     /* Skip whitespace anywhere. */
                  continue;

            if (ch == Pad64)
                  break;

            pos = strchr(Base64, ch);
            if (pos == 0)           /* A non-base64 character. */
                  return (-1);

            switch (state) {
            case 0:
                  if (target) {
                        if ((size_t)tarindex >= targsize)
                              return (-1);
                        target[tarindex] = (pos - Base64) << 2;
                  }
                  state = 1;
                  break;
            case 1:
                  if (target) {
                        if ((size_t)tarindex + 1 >= targsize)
                              return (-1);
                        target[tarindex]   |=  (pos - Base64) >> 4;
                        target[tarindex+1]  = ((pos - Base64) & 0x0f)
                                          << 4 ;
                  }
                  tarindex++;
                  state = 2;
                  break;
            case 2:
                  if (target) {
                        if ((size_t)tarindex + 1 >= targsize)
                              return (-1);
                        target[tarindex]   |=  (pos - Base64) >> 2;
                        target[tarindex+1]  = ((pos - Base64) & 0x03)
                                          << 6;
                  }
                  tarindex++;
                  state = 3;
                  break;
            case 3:
                  if (target) {
                        if ((size_t)tarindex >= targsize)
                              return (-1);
                        target[tarindex] |= (pos - Base64);
                  }
                  tarindex++;
                  state = 0;
                  break;
            default:
                  abort();
            }
      }

      /*
       * We are done decoding Base-64 chars.  Let's see if we ended
       * on a byte boundary, and/or with erroneous trailing characters.
       */

      if (ch == Pad64) {            /* We got a pad char. */
            ch = *src++;            /* Skip it, get next. */
            switch (state) {
            case 0:           /* Invalid = in first position */
            case 1:           /* Invalid = in second position */
                  return (-1);

            case 2:           /* Valid, means one byte of info */
                  /* Skip any number of spaces. */
                  for ((void)NULL; ch != '\0'; ch = *src++)
                        if (! (isascii(ch) && isspace(ch)))
                              break;
                  /* Make sure there is another trailing = sign. */
                  if (ch != Pad64)
                        return (-1);
                  ch = *src++;            /* Skip the = */
                  /* Fall through to "single trailing =" case. */
                  /* FALLTHROUGH */

            case 3:           /* Valid, means two bytes of info */
                  /*
                   * We know this char is an =.  Is there anything but
                   * whitespace after it?
                   */
                  for ((void)NULL; ch != '\0'; ch = *src++)
                        if (! (isascii(ch) && isspace(ch)))
                              return (-1);

                  /*
                   * Now make sure for cases 2 and 3 that the "extra"
                   * bits that slopped past the last full byte were
                   * zeros.  If we don't check them, they become a
                   * subliminal channel.
                   */
                  if (target && target[tarindex] != 0)
                        return (-1);
            }
      } else {
            /*
             * We ended by seeing the end of the string.  Make sure we
             * have no partial bytes lying around.
             */
            if (state != 0)
                  return (-1);
      }

      return (tarindex);
}

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