usr/src/lib/libresolv2/common/isc/base64.c

   1 /*
   2  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
   3  * Use is subject to license terms.
   4  */
   5
   6
   7 /*
   8  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
   9  * Copyright (c) 1996-1999 by Internet Software Consortium.
  10  *
  11  * Permission to use, copy, modify, and distribute this software for any
  12  * purpose with or without fee is hereby granted, provided that the above
  13  * copyright notice and this permission notice appear in all copies.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
  16  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  17  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  18  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  19  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  20  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  21  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  22  */
  23
  24 /*
  25  * Portions Copyright (c) 1995 by International Business Machines, Inc.
  26  *
  27  * International Business Machines, Inc. (hereinafter called IBM) grants
  28  * permission under its copyrights to use, copy, modify, and distribute this
  29  * Software with or without fee, provided that the above copyright notice and
  30  * all paragraphs of this notice appear in all copies, and that the name of IBM
  31  * not be used in connection with the marketing of any product incorporating
  32  * the Software or modifications thereof, without specific, written prior
  33  * permission.
  34  *
  35  * To the extent it has a right to do so, IBM grants an immunity from suit
  36  * under its patents, if any, for the use, sale or manufacture of products to
  37  * the extent that such products are used for performing Domain Name System
  38  * dynamic updates in TCP/IP networks by means of the Software.  No immunity is
  39  * granted for any product per se or for any other function of any product.
  40  *
  41  * THE SOFTWARE IS PROVIDED "AS IS", AND IBM DISCLAIMS ALL WARRANTIES,
  42  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
  43  * PARTICULAR PURPOSE.  IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL,
  44  * DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER ARISING
  45  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE, EVEN
  46  * IF IBM IS APPRISED OF THE POSSIBILITY OF SUCH DAMAGES.
  47  */
  48
  49 #if !defined(LINT) && !defined(CODECENTER)
  50 static const char rcsid[] = "$Id: base64.c,v 1.4 2005/04/27 04:56:34 sra Exp $";
  51 #endif /* not lint */
  52
  53 #include "port_before.h"
  54
  55 #include <sys/types.h>
  56 #include <sys/param.h>
  57 #include <sys/socket.h>
  58
  59 #include <netinet/in.h>
  60 #include <arpa/inet.h>
  61 #include <arpa/nameser.h>
  62
  63 #include <ctype.h>
  64 #include <resolv.h>
  65 #include <stdio.h>
  66 #include <stdlib.h>
  67 #include <string.h>
  68
  69 #include "port_after.h"
  70
  71 #ifndef ORIGINAL_ISC_CODE
  72 #pragma weak    __b64_ntop      =       b64_ntop
  73 #pragma weak    __b64_pton      =       b64_pton
  74 #endif  /* ORIGINAL_ISC_CODE */
  75
  76 #define Assert(Cond) if (!(Cond)) abort()
  77
  78 static const char Base64[] =
  79         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  80 static const char Pad64 = '=';
  81
  82 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
  83    The following encoding technique is taken from RFC1521 by Borenstein
  84    and Freed.  It is reproduced here in a slightly edited form for
  85    convenience.
  86
  87    A 65-character subset of US-ASCII is used, enabling 6 bits to be
  88    represented per printable character. (The extra 65th character, "=",
  89    is used to signify a special processing function.)
  90
  91    The encoding process represents 24-bit groups of input bits as output
  92    strings of 4 encoded characters. Proceeding from left to right, a
  93    24-bit input group is formed by concatenating 3 8-bit input groups.
  94    These 24 bits are then treated as 4 concatenated 6-bit groups, each
  95    of which is translated into a single digit in the base64 alphabet.
  96
  97    Each 6-bit group is used as an index into an array of 64 printable
  98    characters. The character referenced by the index is placed in the
  99    output string.
 100
 101                          Table 1: The Base64 Alphabet
 102
 103       Value Encoding  Value Encoding  Value Encoding  Value Encoding
 104           0 A            17 R            34 i            51 z
 105           1 B            18 S            35 j            52 0
 106           2 C            19 T            36 k            53 1
 107           3 D            20 U            37 l            54 2
 108           4 E            21 V            38 m            55 3
 109           5 F            22 W            39 n            56 4
 110           6 G            23 X            40 o            57 5
 111           7 H            24 Y            41 p            58 6
 112           8 I            25 Z            42 q            59 7
 113           9 J            26 a            43 r            60 8
 114          10 K            27 b            44 s            61 9
 115          11 L            28 c            45 t            62 +
 116          12 M            29 d            46 u            63 /
 117          13 N            30 e            47 v
 118          14 O            31 f            48 w         (pad) =
 119          15 P            32 g            49 x
 120          16 Q            33 h            50 y
 121
 122    Special processing is performed if fewer than 24 bits are available
 123    at the end of the data being encoded.  A full encoding quantum is
 124    always completed at the end of a quantity.  When fewer than 24 input
 125    bits are available in an input group, zero bits are added (on the
 126    right) to form an integral number of 6-bit groups.  Padding at the
 127    end of the data is performed using the '=' character.
 128
 129    Since all base64 input is an integral number of octets, only the
 130          -------------------------------------------------
 131    following cases can arise:
 132
 133        (1) the final quantum of encoding input is an integral
 134            multiple of 24 bits; here, the final unit of encoded
 135            output will be an integral multiple of 4 characters
 136            with no "=" padding,
 137        (2) the final quantum of encoding input is exactly 8 bits;
 138            here, the final unit of encoded output will be two
 139            characters followed by two "=" padding characters, or
 140        (3) the final quantum of encoding input is exactly 16 bits;
 141            here, the final unit of encoded output will be three
 142            characters followed by one "=" padding character.
 143    */
 144
 145 int
 146 b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize) {
 147         size_t datalength = 0;
 148         u_char input[3];
 149         u_char output[4];
 150         size_t i;
 151
 152         while (2U < srclength) {
 153                 input[0] = *src++;
 154                 input[1] = *src++;
 155                 input[2] = *src++;
 156                 srclength -= 3;
 157
 158                 output[0] = input[0] >> 2;
 159                 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
 160                 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
 161                 output[3] = input[2] & 0x3f;
 162                 Assert(output[0] < 64);
 163                 Assert(output[1] < 64);
 164                 Assert(output[2] < 64);
 165                 Assert(output[3] < 64);
 166
 167                 if (datalength + 4 > targsize)
 168                         return (-1);
 169                 target[datalength++] = Base64[output[0]];
 170                 target[datalength++] = Base64[output[1]];
 171                 target[datalength++] = Base64[output[2]];
 172                 target[datalength++] = Base64[output[3]];
 173         }
 174
 175         /* Now we worry about padding. */
 176         if (0U != srclength) {
 177                 /* Get what's left. */
 178                 input[0] = input[1] = input[2] = '\0';
 179                 for (i = 0; i < srclength; i++)
 180                         input[i] = *src++;
 181
 182                 output[0] = input[0] >> 2;
 183                 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
 184                 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
 185                 Assert(output[0] < 64);
 186                 Assert(output[1] < 64);
 187                 Assert(output[2] < 64);
 188
 189                 if (datalength + 4 > targsize)
 190                         return (-1);
 191                 target[datalength++] = Base64[output[0]];
 192                 target[datalength++] = Base64[output[1]];
 193                 if (srclength == 1U)
 194                         target[datalength++] = Pad64;
 195                 else
 196                         target[datalength++] = Base64[output[2]];
 197                 target[datalength++] = Pad64;
 198         }
 199         if (datalength >= targsize)
 200                 return (-1);
 201         target[datalength] = '\0';      /*%< Returned value doesn't count \\0. */
 202         return (datalength);
 203 }
 204
 205 /* skips all whitespace anywhere.
 206    converts characters, four at a time, starting at (or after)
 207    src from base - 64 numbers into three 8 bit bytes in the target area.
 208    it returns the number of data bytes stored at the target, or -1 on error.
 209  */
 210
 211 int
 212 b64_pton(src, target, targsize)
 213         char const *src;
 214         u_char *target;
 215         size_t targsize;
 216 {
 217         int tarindex, state, ch;
 218         char *pos;
 219
 220         state = 0;
 221         tarindex = 0;
 222
 223         while ((ch = *src++) != '\0') {
 224                 if (isspace(ch))        /*%< Skip whitespace anywhere. */
 225                         continue;
 226
 227                 if (ch == Pad64)
 228                         break;
 229
 230                 pos = strchr(Base64, ch);
 231                 if (pos == 0)           /*%< A non-base64 character. */
 232                         return (-1);
 233
 234                 switch (state) {
 235                 case 0:
 236                         if (target) {
 237                                 if ((size_t)tarindex >= targsize)
 238                                         return (-1);
 239                                 target[tarindex] = (pos - Base64) << 2;
 240                         }
 241                         state = 1;
 242                         break;
 243                 case 1:
 244                         if (target) {
 245                                 if ((size_t)tarindex + 1 >= targsize)
 246                                         return (-1);
 247                                 target[tarindex]   |=  (pos - Base64) >> 4;
 248                                 target[tarindex+1]  = ((pos - Base64) & 0x0f)
 249                                                         << 4 ;
 250                         }
 251                         tarindex++;
 252                         state = 2;
 253                         break;
 254                 case 2:
 255                         if (target) {
 256                                 if ((size_t)tarindex + 1 >= targsize)
 257                                         return (-1);
 258                                 target[tarindex]   |=  (pos - Base64) >> 2;
 259                                 target[tarindex+1]  = ((pos - Base64) & 0x03)
 260                                                         << 6;
 261                         }
 262                         tarindex++;
 263                         state = 3;
 264                         break;
 265                 case 3:
 266                         if (target) {
 267                                 if ((size_t)tarindex >= targsize)
 268                                         return (-1);
 269                                 target[tarindex] |= (pos - Base64);
 270                         }
 271                         tarindex++;
 272                         state = 0;
 273                         break;
 274                 default:
 275                         abort();
 276                 }
 277         }
 278
 279         /*
 280          * We are done decoding Base-64 chars.  Let's see if we ended
 281          * on a byte boundary, and/or with erroneous trailing characters.
 282          */
 283
 284         if (ch == Pad64) {              /*%< We got a pad char. */
 285                 ch = *src++;            /*%< Skip it, get next. */
 286                 switch (state) {
 287                 case 0:         /*%< Invalid = in first position */
 288                 case 1:         /*%< Invalid = in second position */
 289                         return (-1);
 290
 291                 case 2:         /*%< Valid, means one byte of info */
 292                         /* Skip any number of spaces. */
 293                         for ((void)NULL; ch != '\0'; ch = *src++)
 294                                 if (!isspace(ch))
 295                                         break;
 296                         /* Make sure there is another trailing = sign. */
 297                         if (ch != Pad64)
 298                                 return (-1);
 299                         ch = *src++;            /*%< Skip the = */
 300                         /* Fall through to "single trailing =" case. */
 301                         /* FALLTHROUGH */
 302
 303                 case 3:         /*%< Valid, means two bytes of info */
 304                         /*
 305                          * We know this char is an =.  Is there anything but
 306                          * whitespace after it?
 307                          */
 308                         for ((void)NULL; ch != '\0'; ch = *src++)
 309                                 if (!isspace(ch))
 310                                         return (-1);
 311
 312                         /*
 313                          * Now make sure for cases 2 and 3 that the "extra"
 314                          * bits that slopped past the last full byte were
 315                          * zeros.  If we don't check them, they become a
 316                          * subliminal channel.
 317                          */
 318                         if (target && target[tarindex] != 0)
 319                                 return (-1);
 320                 }
 321         } else {
 322                 /*
 323                  * We ended by seeing the end of the string.  Make sure we
 324                  * have no partial bytes lying around.
 325                  */
 326                 if (state != 0)
 327                         return (-1);
 328         }
 329
 330         return (tarindex);
 331 }
 332
 333 /*! \file */