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/*

 * 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.

 */

#if !defined(__rtems__)

#if !defined(LINT) && !defined(CODECENTER)

static char rcsid[] = "$Id: base64.c,v 1.2 2001-09-27 12:01:53 chris Exp $";

#endif /* not lint */

#endif /* not rtems */

#include <sys/types.h>

#include <sys/param.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <arpa/inet.h>

#include <arpa/nameser.h>

#include <ctype.h>

#include <resolv.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#define Assert(Cond) if (!(Cond)) abort()

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

          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.

   */

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];

        size_t 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;

                Assert(output[0] < 64);

                Assert(output[1] < 64);

                Assert(output[2] < 64);

                Assert(output[3] < 64);

                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);

                Assert(output[0] < 64);

                Assert(output[1] < 64);

                Assert(output[2] < 64);

                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);

}

/* 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(src, target, targsize)

        char const *src;

        u_char *target;

        size_t targsize;

{

        int tarindex, state, 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 ((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 (!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 (!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);

}