OSX/libsecurity_cdsa_utils/lib/cuEnc64.c

   1 /*
   2  * Copyright (c) 1998-2003,2011,2014 Apple Inc. All Rights Reserved.
   3  *
   4  * The contents of this file constitute Original Code as defined in and are
   5  * subject to the Apple Public Source License Version 1.2 (the 'License').
   6  * You may not use this file except in compliance with the License. Please
   7  * obtain a copy of the License at http://www.apple.com/publicsource and
   8  * read it before using this file.
   9  *
  10  * This Original Code and all software distributed under the License are
  11  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  12  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  13  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  14  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  15  * Please see the License for the specific language governing rights and
  16  * limitations under the License.
  17  *
  18  * cuEnc64.c - encode/decode in 64-char IA5 format, per RFC 1421
  19  */
  20
  21 #include "cuEnc64.h"
  22 #include <stdlib.h>
  23
  24 #ifndef NULL
  25 #define NULL ((void *)0)
  26 #endif  /* NULL */
  27
  28 /*
  29  * map a 6-bit binary value to a printable character.
  30  */
  31 static const
  32 unsigned char bintoasc[] =
  33         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  34
  35 /*
  36  * Map an 7-bit printable character to its corresponding binary value.
  37  * Any illegal characters return high bit set.
  38  */
  39 static const
  40 unsigned char asctobin[] =
  41 {
  42     0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
  43     0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
  44     0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
  45     0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
  46     0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
  47     0x80, 0x80, 0x80, 0x3e, 0x80, 0x80, 0x80, 0x3f,
  48     0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b,
  49     0x3c, 0x3d, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
  50     0x80, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,
  51     0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e,
  52     0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16,
  53     0x17, 0x18, 0x19, 0x80, 0x80, 0x80, 0x80, 0x80,
  54     0x80, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20,
  55     0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28,
  56     0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30,
  57     0x31, 0x32, 0x33, 0x80, 0x80, 0x80, 0x80, 0x80
  58 };
  59
  60 /*
  61  * map 6 bits to a printing char
  62  */
  63 #define ENC(c) (bintoasc[((c) & 0x3f)])
  64
  65 #define PAD             '='
  66
  67 /*
  68  * map one group of up to 3 bytes at inp to 4 bytes at outp.
  69  * Count is number of valid bytes in *inp; if less than 3, the
  70  * 1 or two extras must be zeros.
  71  */
  72 static void encChunk(const unsigned char *inp,
  73         unsigned char *outp,
  74         int count)
  75 {
  76         unsigned char c1, c2, c3, c4;
  77
  78         c1 = *inp >> 2;
  79         c2 = ((inp[0] << 4) & 0x30) | ((inp[1] >> 4) & 0xf);
  80         c3 = ((inp[1] << 2) & 0x3c) | ((inp[2] >> 6) & 0x3);
  81         c4 = inp[2] & 0x3f;
  82         *outp++ = ENC(c1);
  83         *outp++ = ENC(c2);
  84         if (count == 1) {
  85             *outp++ = PAD;
  86             *outp   = PAD;
  87         } else {
  88             *outp++ = ENC(c3);
  89             if (count == 2) {
  90                 *outp = PAD;
  91             }
  92             else {
  93                 *outp = ENC(c4);
  94             }
  95         }
  96 }
  97
  98 /*
  99  * Given input buffer inbuf, length inlen, encode to 64-char IA5 format.
 100  * Result is fmalloc'd and returned; it is terminated by Microsoft-style
 101  * newline and NULL. Its length (including the trailing newline and NULL)
 102  * is returned in *outlen.
 103  */
 104
 105 unsigned char *cuEnc64(const unsigned char *inbuf,
 106         unsigned inlen,
 107         unsigned *outlen)               // RETURNED
 108 {
 109         return cuEnc64WithLines(inbuf, inlen, 0, outlen);
 110 }
 111
 112 unsigned char *cuEnc64WithLines(const unsigned char *inbuf,
 113         unsigned inlen,
 114         unsigned linelen,
 115         unsigned *outlen)
 116 {
 117         unsigned                outTextLen;
 118         unsigned                len;                    // to malloc, liberal
 119         unsigned                olen = 0;               // actual output size
 120         unsigned char   *outbuf;
 121         unsigned char   endbuf[3];
 122         unsigned                i;
 123         unsigned char   *outp;
 124         unsigned                numLines;
 125         unsigned                thisLine;
 126
 127         outTextLen = ((inlen + 2) / 3) * 4;
 128         if(linelen) {
 129             /*
 130              * linelen must be 0 mod 4 for this to work; round up...
 131              */
 132             if((linelen & 0x03) != 0) {
 133                 linelen = (linelen + 3) & 0xfffffffc;
 134             }
 135             numLines = (outTextLen + linelen - 1)/ linelen;
 136         }
 137         else {
 138             numLines = 1;
 139         }
 140
 141         /*
 142          * Total output size = encoded text size plus one newline per
 143          * line of output, plus trailing NULL. We always generate newlines
 144          * as \n; when decoding, we tolerate \r\n (Microsoft) or \n.
 145          */
 146         len = outTextLen + (2 * numLines) + 1;
 147         outbuf = (unsigned char*)malloc(len);
 148         outp = outbuf;
 149         thisLine = 0;
 150
 151         while(inlen) {
 152             if(inlen < 3) {
 153                         for(i=0; i<3; i++) {
 154                                 if(i < inlen) {
 155                                         endbuf[i] = inbuf[i];
 156                                 }
 157                                 else {
 158                                         endbuf[i] = 0;
 159                                 }
 160                         }
 161                         encChunk(endbuf, outp, inlen);
 162                         inlen = 0;
 163             }
 164             else {
 165                         encChunk(inbuf, outp, 3);
 166                         inlen -= 3;
 167                         inbuf += 3;
 168             }
 169             outp += 4;
 170             thisLine += 4;
 171             olen += 4;
 172             if((linelen != 0) && (thisLine >= linelen) && inlen) {
 173                 /*
 174                          * last trailing newline added below
 175                          * Note we don't split 4-byte output chunks over newlines
 176                          */
 177                 *outp++ = '\n';
 178                         olen++;
 179                         thisLine = 0;
 180             }
 181         }
 182         *outp++ = '\n';
 183         *outp = '\0';
 184         olen += 2;
 185         *outlen = olen;
 186         return outbuf;
 187 }
 188
 189 static inline int isWhite(unsigned char c)
 190 {
 191         switch(c) {
 192             case '\n':
 193             case '\r':
 194             case ' ':
 195             case '\t':
 196             case '\0':
 197                         return 1;
 198             default:
 199                         return 0;
 200         }
 201 }
 202
 203 /*
 204  * Strip off all whitespace from a (supposedly) enc64-format string.
 205  * Returns a malloc'd string.
 206  */
 207 static unsigned char *stringCleanse(const unsigned char *inbuf,
 208         unsigned inlen,
 209         unsigned *outlen)
 210 {
 211         unsigned char   *news;                  // cleansed inbuf
 212         unsigned                newsDex;                // index into news
 213         unsigned                i;
 214
 215         news = (unsigned char*)malloc(inlen);
 216         newsDex = 0;
 217         for(i=0; i<inlen; i++) {
 218             if(!isWhite(inbuf[i])) {
 219                 news[newsDex++] = inbuf[i];
 220             }
 221         }
 222         *outlen = newsDex;
 223         return news;
 224 }
 225
 226 /*
 227  * Given input buffer inbuf, length inlen, decode from 64-char IA5 format to
 228  * binary. Result is malloced and returned; its length is returned in *outlen.
 229  * NULL return indicates corrupted input.
 230  *
 231  * All whitespace in input is ignored.
 232  */
 233 unsigned char *cuDec64(const unsigned char *inbuf,
 234         unsigned inlen,
 235         unsigned *outlen)
 236 {
 237         unsigned char           *outbuf;
 238         unsigned char           *outp;                  // malloc'd outbuf size
 239         unsigned                        obuflen;
 240         const unsigned char     *bp;
 241         unsigned                        olen = 0;               // actual output size
 242         unsigned char           c1, c2, c3, c4;
 243         unsigned char           j;
 244         unsigned                        thisOlen;
 245         unsigned char           *news;                  // cleansed inbuf
 246         unsigned                        newsLen;
 247
 248         /*
 249          * Strip out all whitespace; remainder must be multiple of four
 250          * characters
 251          */
 252         news = stringCleanse(inbuf, inlen, &newsLen);
 253         if((newsLen & 0x03) != 0) {
 254             free(news);
 255             return (unsigned char*) NULL;
 256         }
 257         inlen = newsLen;
 258         bp = news;
 259
 260         obuflen = (inlen / 4) * 3;
 261         outbuf = (unsigned char*)malloc(obuflen);
 262         outp = outbuf;
 263
 264         while (inlen) {
 265             /*
 266              * Note inlen is always a multiple of four here
 267              */
 268             if (*bp & 0x80 || (c1 = asctobin[*bp]) & 0x80) {
 269                 goto errorOut;
 270             }
 271             inlen--;
 272             bp++;
 273             if (*bp & 0x80 || (c2 = asctobin[*bp]) & 0x80){
 274                 goto errorOut;
 275             }
 276             inlen--;
 277             bp++;
 278             if (*bp == PAD) {
 279                         /*
 280                          * two input bytes, one output byte
 281                          */
 282                         c3 = c4 = 0;
 283                         thisOlen = 1;
 284                         if (c2 & 0xf) {
 285                                 goto errorOut;
 286                         }
 287                         bp++;
 288                         inlen--;
 289                         if (*bp == PAD) {
 290                                 bp++;
 291                                 inlen--;
 292                                 if(inlen > 0) {
 293                                         goto errorOut;
 294                                 }
 295                         }
 296                         else {
 297                                 goto errorOut;
 298                         }
 299             } else if (*bp & 0x80 || (c3 = asctobin[*bp]) & 0x80) {
 300                 goto errorOut;
 301             } else {
 302                 bp++;
 303                 inlen--;
 304                 if (*bp == PAD) {
 305                     /*
 306                      * Three input bytes, two output
 307                      */
 308                     c4 = 0;
 309                     thisOlen = 2;
 310                     if (c3 & 3) {
 311                                 goto errorOut;
 312                     }
 313                 } else if (*bp & 0x80 || (c4 = asctobin[*bp]) & 0x80) {
 314                     goto errorOut;
 315                 } else {
 316                     /*
 317                      * Normal non-pad case
 318                      */
 319                     thisOlen = 3;
 320                 }
 321                 bp++;
 322                 inlen--;
 323             }
 324             j = (c1 << 2) | (c2 >> 4);
 325             *outp++ = j;
 326             if(thisOlen > 1) {
 327                         j = (c2 << 4) | (c3 >> 2);
 328                         *outp++ = j;
 329                         if(thisOlen == 3) {
 330                                 j = (c3 << 6) | c4;
 331                                 *outp++ = j;
 332                         }
 333             }
 334             olen += thisOlen;
 335         }
 336         free(news);
 337         *outlen = olen;
 338         return outbuf;                  /* normal return */
 339
 340 errorOut:
 341         free(news);
 342         free(outbuf);
 343         return (unsigned char*) NULL;
 344 }
 345
 346 /*
 347  * Determine if specified input data is valid enc64 format. Returns 1
 348  * if valid, 0 if not.
 349  * This doesn't do a full enc64 parse job; it scans for legal characters
 350  * and proper sync when a possible pad is found.
 351  */
 352 int cuIsValidEnc64(const unsigned char *inbuf,
 353         unsigned inlen)
 354 {
 355         int padChars = 0;       // running count of PAD chars
 356         int validEncChars = 0;
 357         unsigned char c;
 358
 359         /*
 360          *   -- scan inbuf
 361          *   -- skip whitespace
 362          *   -- count valid chars
 363          *   -- ensure not more than 2 PAD chars, only at end
 364          *   -- ensure valid chars mod 4 == 0
 365          */
 366
 367         while(inlen) {
 368             c = *inbuf++;
 369             inlen--;
 370             if(isWhite(c)) {
 371                 continue;
 372             }
 373             if(c == PAD) {
 374                         if(++padChars > 2) {
 375                                 return 0;               // max of 2 PAD chars at end
 376                         }
 377             }
 378             else if(padChars > 0) {
 379                         return 0;               // no normal chars after seeing PAD
 380             }
 381             else if((c & 0x80) || ((asctobin[c]) & 0x80)) {
 382                         return 0;               // invalid encoded char
 383             }
 384             validEncChars++;
 385         }
 386         if((validEncChars & 0x03) != 0) {
 387             return 0;
 388         }
 389         else {
 390             return 1;
 391         }
 392 }