text: /*
   * 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 <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  
  #include "kms_message/kms_b64.h"
  #include "kms_message/kms_message.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
   *        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.
   */
  
  int
  kms_message_b64_ntop (uint8_t const *src,
                        size_t srclength,
                        char *target,
                        size_t targsize)
  {
     size_t datalength = 0;
     uint8_t input[3];
     uint8_t 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 (int) datalength;
  }
  
  /* (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.
     */
  
  /* 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.
   */
  
  static uint8_t b64rmap[256];
  
  static const uint8_t b64rmap_special = 0xf0;
  static const uint8_t b64rmap_end = 0xfd;
  static const uint8_t b64rmap_space = 0xfe;
  static const uint8_t b64rmap_invalid = 0xff;
  
  void
  kms_message_b64_initialize_rmap (void)
  {
     int i;
     unsigned char ch;
  
     /* Null: end of string, stop parsing */
     b64rmap[0] = b64rmap_end;
  
     for (i = 1; i < 256; ++i) {
        ch = (unsigned char) i;
        /* Whitespaces */
        if (isspace (ch))
           b64rmap[i] = b64rmap_space;
        /* Padding: stop parsing */
        else if (ch == Pad64)
           b64rmap[i] = b64rmap_end;
        /* Non-base64 char */
        else
           b64rmap[i] = b64rmap_invalid;
     }
  
     /* Fill reverse mapping for base64 chars */
     for (i = 0; Base64[i] != '\0'; ++i)
        b64rmap[(uint8_t) Base64[i]] = i;
  }
  
  static int
  b64_pton_do (char const *src, uint8_t *target, size_t targsize)
  {
     int tarindex, state, ch;
     uint8_t ofs;
  
     state = 0;
     tarindex = 0;
  
     while (1) {
        ch = *src++;
        ofs = b64rmap[ch];
  
        if (ofs >= b64rmap_special) {
           /* Ignore whitespaces */
           if (ofs == b64rmap_space)
              continue;
           /* End of base64 characters */
           if (ofs == b64rmap_end)
              break;
           /* A non-base64 character. */
           return (-1);
        }
  
        switch (state) {
        case 0:
           if ((size_t) tarindex >= targsize)
              return (-1);
           target[tarindex] = ofs << 2;
           state = 1;
           break;
        case 1:
           if ((size_t) tarindex + 1 >= targsize)
              return (-1);
           target[tarindex] |= ofs >> 4;
           target[tarindex + 1] = (ofs & 0x0f) << 4;
           tarindex++;
           state = 2;
           break;
        case 2:
           if ((size_t) tarindex + 1 >= targsize)
              return (-1);
           target[tarindex] |= ofs >> 2;
           target[tarindex + 1] = (ofs & 0x03) << 6;
           tarindex++;
           state = 3;
           break;
        case 3:
           if ((size_t) tarindex >= targsize)
              return (-1);
           target[tarindex] |= ofs;
           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 (b64rmap[ch] != b64rmap_space)
                 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 (b64rmap[ch] != b64rmap_space)
                 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[tarindex] != 0)
              return (-1);
        default:
           break;
        }
     } 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);
  }
  
  
  static int
  b64_pton_len (char const *src)
  {
     int tarindex, state, ch;
     uint8_t ofs;
  
     state = 0;
     tarindex = 0;
  
     while (1) {
        ch = *src++;
        ofs = b64rmap[ch];
  
        if (ofs >= b64rmap_special) {
           /* Ignore whitespaces */
           if (ofs == b64rmap_space)
              continue;
           /* End of base64 characters */
           if (ofs == b64rmap_end)
              break;
           /* A non-base64 character. */
           return (-1);
        }
  
        switch (state) {
        case 0:
           state = 1;
           break;
        case 1:
           tarindex++;
           state = 2;
           break;
        case 2:
           tarindex++;
           state = 3;
           break;
        case 3:
           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 (b64rmap[ch] != b64rmap_space)
                 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 (b64rmap[ch] != b64rmap_space)
                 return (-1);
  
        default:
           break;
        }
     } 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);
  }
  
  
  int
  kms_message_b64_pton (char const *src, uint8_t *target, size_t targsize)
  {
     if (target)
        return b64_pton_do (src, target, targsize);
     else
        return b64_pton_len (src);
  }
  
  int
  kms_message_b64_to_b64url (const char *src,
                             size_t srclength,
                             char *target,
                             size_t targsize)
  {
     size_t i;
  
     for (i = 0; i < srclength; i++) {
        if (src[i] == '=') {
           break;
        }
  
        if (i >= targsize) {
           return -1;
        }
  
        target[i] = src[i];
        if (target[i] == '+') {
           target[i] = '-';
        } else if (target[i] == '/') {
           target[i] = '_';
        }
     }
  
     /* NULL terminate if room. */
     if (i < targsize) {
        target[i] = '\0';
     }
  
     return (int) i;
  }
  
  int
  kms_message_b64url_to_b64 (const char *src,
                             size_t srclength,
                             char *target,
                             size_t targsize)
  {
     size_t i;
     size_t boundary;
  
     for (i = 0; i < srclength; i++) {
        if (src[i] == '=') {
           break;
        }
  
        if (i >= targsize) {
           return -1;
        }
  
        target[i] = src[i];
        if (target[i] == '-') {
           target[i] = '+';
        } else if (target[i] == '_') {
           target[i] = '/';
        }
     }
  
     /* Pad to four byte boundary. */
     boundary = 4 * ((i + 3) / 4);
     for (; i < boundary; i++) {
        if (i >= targsize) {
           return -1;
        }
        target[i] = '=';
     }
  
     /* NULL terminate if room. */
     if (i < targsize) {
        target[i] = '\0';
     }
  
     return (int) i;
  }
  
  char *
  kms_message_raw_to_b64 (const uint8_t *raw, size_t raw_len)
  {
     char *b64;
     size_t b64_len;
  
     b64_len = (raw_len / 3 + 1) * 4 + 1;
     b64 = malloc (b64_len);
     memset (b64, 0, b64_len);
     if (-1 == kms_message_b64_ntop (raw, raw_len, b64, b64_len)) {
        free (b64);
        return NULL;
     }
     return b64;
  }
  
  uint8_t *
  kms_message_b64_to_raw (const char *b64, size_t *out)
  {
     uint8_t *raw;
     int ret;
     size_t b64len;
  
     b64len = strlen (b64);
     raw = (uint8_t *) malloc (b64len + 1);
     memset (raw, 0, b64len + 1);
     ret = kms_message_b64_pton (b64, raw, b64len);
     if (ret > 0) {
        *out = (size_t) ret;
        return raw;
     }
     free (raw);
     return NULL;
  }
  
  char *
  kms_message_raw_to_b64url (const uint8_t *raw, size_t raw_len)
  {
     char *b64;
     size_t b64len;
  
     b64 = kms_message_raw_to_b64 (raw, raw_len);
     if (!b64) {
        return NULL;
     }
  
     b64len = strlen (b64);
     if (-1 == kms_message_b64_to_b64url (b64, b64len, b64, b64len)) {
        free (b64);
        return NULL;
     }
  
     return b64;
  }
  
  uint8_t *
  kms_message_b64url_to_raw (const char *b64url, size_t *out)
  {
     char *b64;
     size_t capacity;
     uint8_t *raw;
     size_t b64urllen;
  
     b64urllen = strlen(b64url);
     /* Add four for padding '=' characters. */
     capacity = b64urllen + 4;
     b64 = malloc (capacity);
     memset (b64, 0, capacity);
     if (-1 ==
         kms_message_b64url_to_b64 (b64url, b64urllen, b64, capacity)) {
        free (b64);
        return NULL;
     }
     raw = kms_message_b64_to_raw (b64, out);
     free (b64);
     return raw;
  }