/*  $OpenBSD: base64.c,v 1.5 2006/10/21 09:55:03 otto Exp $ */

/*

 * Copyright (c) 1996 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.

 */

/* OPENBSD ORIGINAL: lib/libc/net/base64.c */

#include "includes.h"

#if (!defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP)) || (!defined(HAVE_B64_PTON) && !defined(HAVE___B64_PTON))

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <ctype.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include "base64.h"

static const char Base64[] =

  "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

static const char Pad64 = '=';

/* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)

   The following encoding technique is taken from RFC 1521 by Borenstein

   and Freed.  It is reproduced here in a slightly edited form for

   convenience.

   A 65-character subset of US-ASCII is used, enabling 6 bits to be

   represented per printable character. (The extra 65th character, "=",

   is used to signify a special processing function.)

   The encoding process represents 24-bit groups of input bits as output

   strings of 4 encoded characters. Proceeding from left to right, a

   24-bit input group is formed by concatenating 3 8-bit input groups.

   These 24 bits are then treated as 4 concatenated 6-bit groups, each

   of which is translated into a single digit in the base64 alphabet.

   Each 6-bit group is used as an index into an array of 64 printable

   characters. The character referenced by the index is placed in the

   output string.

                         Table 1: The Base64 Alphabet

      Value Encoding  Value Encoding  Value Encoding  Value Encoding

          0 A            17 R            34 i            51 z

          1 B            18 S            35 j            52 0

          2 C            19 T            36 k            53 1

          3 D            20 U            37 l            54 2

          4 E            21 V            38 m            55 3

          5 F            22 W            39 n            56 4

          6 G            23 X            40 o            57 5

          7 H            24 Y            41 p            58 6

          8 I            25 Z            42 q            59 7

          9 J            26 a            43 r            60 8

         10 K            27 b            44 s            61 9

         11 L            28 c            45 t            62 +

         12 M            29 d            46 u            63 /

         13 N            30 e            47 v

         14 O            31 f            48 w         (pad) =

         15 P            32 g            49 x

         16 Q            33 h            50 y

   Special processing is performed if fewer than 24 bits are available

   at the end of the data being encoded.  A full encoding quantum is

   always completed at the end of a quantity.  When fewer than 24 input

   bits are available in an input group, zero bits are added (on the

   right) to form an integral number of 6-bit groups.  Padding at the

   end of the data is performed using the '=' character.

   Since all base64 input is an integral number of octets, only the

         -------------------------------------------------                       

   following cases can arise:

       (1) the final quantum of encoding input is an integral

           multiple of 24 bits; here, the final unit of encoded

     output will be an integral multiple of 4 characters

     with no "=" padding,

       (2) the final quantum of encoding input is exactly 8 bits;

           here, the final unit of encoded output will be two

     characters followed by two "=" padding characters, or

       (3) the final quantum of encoding input is exactly 16 bits;

           here, the final unit of encoded output will be three

     characters followed by one "=" padding character.

   */

#if !defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP) 

int

b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize)

{

  size_t datalength = 0;

  u_char input[3];

  u_char output[4];

  u_int i;

  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 (datalength + 4 > targsize)

      return (-1);

    target[datalength++] = Base64[output[0]];

    target[datalength++] = Base64[output[1]];

    target[datalength++] = Base64[output[2]];

    target[datalength++] = 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);

    if (datalength + 4 > targsize)

      return (-1);

    target[datalength++] = Base64[output[0]];

    target[datalength++] = Base64[output[1]];

    if (srclength == 1)

      target[datalength++] = Pad64;

    else

      target[datalength++] = Base64[output[2]];

    target[datalength++] = Pad64;

  }

  if (datalength >= targsize)

    return (-1);

  target[datalength] = '\0';  /* Returned value doesn't count \0. */

  return (datalength);

}

#endif /* !defined(HAVE_B64_NTOP) && !defined(HAVE___B64_NTOP) */

#if !defined(HAVE_B64_PTON) && !defined(HAVE___B64_PTON)

/* skips all whitespace anywhere.

   converts characters, four at a time, starting at (or after)

   src from base - 64 numbers into three 8 bit bytes in the target area.

   it returns the number of data bytes stored at the target, or -1 on error.

 */

int

b64_pton(char const *src, u_char *target, size_t targsize)

{

  u_int tarindex, state;

  int ch;

  char *pos;

  state = 0;

  tarindex = 0;

  while ((ch = *src++) != '\0') {

    if (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 (tarindex >= targsize)

          return (-1);

        target[tarindex] = (pos - Base64) << 2;

      }

      state = 1;

      break;

    case 1:

      if (target) {

        if (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 (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 (tarindex >= targsize)

          return (-1);

        target[tarindex] |= (pos - Base64);

      }

      tarindex++;

      state = 0;

      break;

    }

  }

  /*

   * 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 (; ch != '\0'; ch = *src++)

        if (!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 (; ch != '\0'; ch = *src++)

        if (!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);

}

#endif /* !defined(HAVE_B64_PTON) && !defined(HAVE___B64_PTON) */

#endif