lib/utf7.h

   1 /*
   2  * Copyright (C) 1999-2001, 2008, 2016 Free Software Foundation, Inc.
   3  * This file is part of the GNU LIBICONV Library.
   4  *
   5  * The GNU LIBICONV Library is free software; you can redistribute it
   6  * and/or modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either version 2.1
   8  * of the License, or (at your option) any later version.
   9  *
  10  * The GNU LIBICONV Library is distributed in the hope that it will be
  11  * useful, but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with the GNU LIBICONV Library; see the file COPYING.LIB.
  17  * If not, see <https://www.gnu.org/licenses/>.
  18  */
  19
  20 /*
  21  * UTF-7
  22  */
  23
  24 /* Specification: RFC 2152 (and old RFC 1641, RFC 1642) */
  25 /* The original Base64 encoding is defined in RFC 2045. */
  26
  27 /* Set of direct characters:
  28  *   A-Z a-z 0-9 ' ( ) , - . / : ? space tab lf cr
  29  */
  30 static const unsigned char direct_tab[128/8] = {
  31   0x00, 0x26, 0x00, 0x00, 0x81, 0xf3, 0xff, 0x87,
  32   0xfe, 0xff, 0xff, 0x07, 0xfe, 0xff, 0xff, 0x07,
  33 };
  34 #define isdirect(ch) ((ch) < 128 && ((direct_tab[(ch)>>3] >> (ch & 7)) & 1))
  35
  36 /* Set of direct and optional direct characters:
  37  *   A-Z a-z 0-9 ' ( ) , - . / : ? space tab lf cr
  38  *   ! " # $ % & * ; < = > @ [ ] ^ _ ` { | }
  39  */
  40 static const unsigned char xdirect_tab[128/8] = {
  41   0x00, 0x26, 0x00, 0x00, 0xff, 0xf7, 0xff, 0xff,
  42   0xff, 0xff, 0xff, 0xef, 0xff, 0xff, 0xff, 0x3f,
  43 };
  44 #define isxdirect(ch) ((ch) < 128 && ((xdirect_tab[(ch)>>3] >> (ch & 7)) & 1))
  45
  46 /* Set of base64 characters, extended:
  47  *   A-Z a-z 0-9 + / -
  48  */
  49 static const unsigned char xbase64_tab[128/8] = {
  50   0x00, 0x00, 0x00, 0x00, 0x00, 0xa8, 0xff, 0x03,
  51   0xfe, 0xff, 0xff, 0x07, 0xfe, 0xff, 0xff, 0x07,
  52 };
  53 #define isxbase64(ch) ((ch) < 128 && ((xbase64_tab[(ch)>>3] >> (ch & 7)) & 1))
  54
  55 /*
  56  * The state is structured as follows:
  57  * bit 1..0: shift
  58  * bit 7..2: data
  59  * Precise meaning:
  60  *   shift      data
  61  *     0         0           not inside base64 encoding
  62  *     1         0           inside base64, no pending bits
  63  *     2      XXXX00         inside base64, 4 bits remain from 2nd byte
  64  *     3      XX0000         inside base64, 2 bits remain from 3rd byte
  65  */
  66
  67 static int
  68 utf7_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, size_t n)
  69 {
  70   state_t state = conv->istate;
  71   int count = 0; /* number of input bytes already read */
  72   if (state & 3)
  73     goto active;
  74   else
  75     goto inactive;
  76
  77 inactive:
  78   {
  79     /* Here (state & 3) == 0 */
  80     if (n < count+1)
  81       goto none;
  82     {
  83       unsigned char c = *s;
  84       if (isxdirect(c)) {
  85         *pwc = (ucs4_t) c;
  86         conv->istate = state;
  87         return count+1;
  88       }
  89       if (c == '+') {
  90         if (n < count+2)
  91           goto none;
  92         if (s[1] == '-') {
  93           *pwc = (ucs4_t) '+';
  94           conv->istate = state;
  95           return count+2;
  96         }
  97         s++; count++;
  98         state = 1;
  99         goto active;
 100       }
 101       goto ilseq;
 102     }
 103   }
 104
 105 active:
 106   {
 107     /* base64 encoding active */
 108     unsigned int wc = 0;
 109     state_t base64state = state;
 110     unsigned int kmax = 2; /* number of payload bytes to read */
 111     unsigned int k = 0; /* number of payload bytes already read */
 112     unsigned int base64count = 0; /* number of base64 bytes already read */
 113     for (;;) {
 114       unsigned char c = *s;
 115       unsigned int i;
 116       if (c >= 'A' && c <= 'Z')
 117         i = c-'A';
 118       else if (c >= 'a' && c <= 'z')
 119         i = c-'a'+26;
 120       else if (c >= '0' && c <= '9')
 121         i = c-'0'+52;
 122       else if (c == '+')
 123         i = 62;
 124       else if (c == '/')
 125         i = 63;
 126       else {
 127         /* c terminates base64 encoding */
 128         if (base64state & -4)
 129           goto ilseq; /* data must be 0, otherwise illegal */
 130         if (base64count)
 131           goto ilseq; /* partial UTF-16 characters are invalid */
 132         if (c == '-') {
 133           s++; count++;
 134         }
 135         state = 0;
 136         goto inactive;
 137       }
 138       s++; base64count++;
 139       /* read 6 bits: 0 <= i < 64 */
 140       switch (base64state & 3) {
 141         case 1: /* inside base64, no pending bits */
 142           base64state = (i << 2) | 0; break;
 143         case 0: /* inside base64, 6 bits remain from 1st byte */
 144           wc = (wc << 8) | (base64state & -4) | (i >> 4); k++;
 145           base64state = ((i & 15) << 4) | 2; break;
 146         case 2: /* inside base64, 4 bits remain from 2nd byte */
 147           wc = (wc << 8) | (base64state & -4) | (i >> 2); k++;
 148           base64state = ((i & 3) << 6) | 3; break;
 149         case 3: /* inside base64, 2 bits remain from 3rd byte */
 150           wc = (wc << 8) | (base64state & -4) | i; k++;
 151           base64state = 1; break;
 152       }
 153       if (k == kmax) {
 154         /* UTF-16: When we see a High Surrogate, we must also decode
 155            the following Low Surrogate. */
 156         if (kmax == 2 && (wc >= 0xd800 && wc < 0xdc00))
 157           kmax = 4;
 158         else
 159           break;
 160       }
 161       if (n < count+base64count+1)
 162         goto none;
 163     }
 164     /* Here k = kmax > 0, hence base64count > 0. */
 165     if ((base64state & 3) == 0) abort();
 166     if (kmax == 4) {
 167       ucs4_t wc1 = wc >> 16;
 168       ucs4_t wc2 = wc & 0xffff;
 169       if (!(wc1 >= 0xd800 && wc1 < 0xdc00)) abort();
 170       if (!(wc2 >= 0xdc00 && wc2 < 0xe000)) goto ilseq;
 171       *pwc = 0x10000 + ((wc1 - 0xd800) << 10) + (wc2 - 0xdc00);
 172     } else {
 173       *pwc = wc;
 174     }
 175     conv->istate = base64state;
 176     return count+base64count;
 177   }
 178
 179 none:
 180   conv->istate = state;
 181   return RET_TOOFEW(count);
 182
 183 ilseq:
 184   conv->istate = state;
 185   return RET_SHIFT_ILSEQ(count);
 186 }
 187
 188 /*
 189  * The state is structured as follows:
 190  * bit 1..0: shift
 191  * bit 7..2: data
 192  * Precise meaning:
 193  *   shift      data
 194  *     0         0           not inside base64 encoding
 195  *     1         0           inside base64, no pending bits
 196  *     2       XX00          inside base64, 2 bits known for 2nd byte
 197  *     3       XXXX          inside base64, 4 bits known for 3rd byte
 198  */
 199
 200 /* Define this to 1 if you want the so-called "optional direct" characters
 201       ! " # $ % & * ; < = > @ [ ] ^ _ ` { | }
 202    to be encoded. Define to 0 if you want them to be passed straight through,
 203    like the so-called "direct" characters.
 204    We set this to 1 because it's safer.
 205  */
 206 #define UTF7_ENCODE_OPTIONAL_CHARS 1
 207
 208 static int
 209 utf7_wctomb (conv_t conv, unsigned char *r, ucs4_t iwc, size_t n)
 210 {
 211   state_t state = conv->ostate;
 212   unsigned int wc = iwc;
 213   int count = 0;
 214   if (state & 3)
 215     goto active;
 216
 217 /*inactive:*/
 218   {
 219     if (UTF7_ENCODE_OPTIONAL_CHARS ? isdirect(wc) : isxdirect(wc)) {
 220       r[0] = (unsigned char) wc;
 221       /*conv->ostate = state;*/
 222       return 1;
 223     } else {
 224       *r++ = '+';
 225       if (wc == '+') {
 226         if (n < 2)
 227           return RET_TOOSMALL;
 228         *r = '-';
 229         /*conv->ostate = state;*/
 230         return 2;
 231       }
 232       count = 1;
 233       state = 1;
 234       goto active;
 235     }
 236   }
 237
 238 active:
 239   {
 240     /* base64 encoding active */
 241     if (UTF7_ENCODE_OPTIONAL_CHARS ? isdirect(wc) : isxdirect(wc)) {
 242       /* deactivate base64 encoding */
 243       count += ((state & 3) >= 2 ? 1 : 0) + (isxbase64(wc) ? 1 : 0) + 1;
 244       if (n < count)
 245         return RET_TOOSMALL;
 246       if ((state & 3) >= 2) {
 247         unsigned int i = state & -4;
 248         unsigned char c;
 249         if (i < 26)
 250           c = i+'A';
 251         else if (i < 52)
 252           c = i-26+'a';
 253         else if (i < 62)
 254           c = i-52+'0';
 255         else if (i == 62)
 256           c = '+';
 257         else if (i == 63)
 258           c = '/';
 259         else
 260           abort();
 261         *r++ = c;
 262       }
 263       if (isxbase64(wc))
 264         *r++ = '-';
 265       state = 0;
 266       *r++ = (unsigned char) wc;
 267       conv->ostate = state;
 268       return count;
 269     } else {
 270       unsigned int k; /* number of payload bytes to write */
 271       if (wc < 0x10000) {
 272         k = 2;
 273         count += ((state & 3) >= 2 ? 3 : 2);
 274       } else if (wc < 0x110000) {
 275         unsigned int wc1 = 0xd800 + ((wc - 0x10000) >> 10);
 276         unsigned int wc2 = 0xdc00 + ((wc - 0x10000) & 0x3ff);
 277         wc = (wc1 << 16) | wc2;
 278         k = 4;
 279         count += ((state & 3) >= 3 ? 6 : 5);
 280       } else
 281         return RET_ILUNI;
 282       if (n < count)
 283         return RET_TOOSMALL;
 284       for (;;) {
 285         unsigned int i;
 286         unsigned char c;
 287         switch (state & 3) {
 288           case 0: /* inside base64, 6 bits known for 4th byte */
 289             c = (state & -4) >> 2; state = 1; break;
 290           case 1: /* inside base64, no pending bits */
 291             i = (wc >> (8 * --k)) & 0xff;
 292             c = i >> 2; state = ((i & 3) << 4) | 2; break;
 293           case 2: /* inside base64, 2 bits known for 2nd byte */
 294             i = (wc >> (8 * --k)) & 0xff;
 295             c = (state & -4) | (i >> 4); state = ((i & 15) << 2) | 3; break;
 296           case 3: /* inside base64, 4 bits known for 3rd byte */
 297             i = (wc >> (8 * --k)) & 0xff;
 298             c = (state & -4) | (i >> 6); state = ((i & 63) << 2) | 0; break;
 299           default: abort(); /* stupid gcc */
 300         }
 301         if (c < 26)
 302           c = c+'A';
 303         else if (c < 52)
 304           c = c-26+'a';
 305         else if (c < 62)
 306           c = c-52+'0';
 307         else if (c == 62)
 308           c = '+';
 309         else if (c == 63)
 310           c = '/';
 311         else
 312           abort();
 313         *r++ = c;
 314         if ((state & 3) && (k == 0))
 315           break;
 316       }
 317       conv->ostate = state;
 318       return count;
 319     }
 320   }
 321 }
 322
 323 static int
 324 utf7_reset (conv_t conv, unsigned char *r, size_t n)
 325 {
 326   state_t state = conv->ostate;
 327   if (state & 3) {
 328     /* deactivate base64 encoding */
 329     unsigned int count = ((state & 3) >= 2 ? 1 : 0) + 1;
 330     if (n < count)
 331       return RET_TOOSMALL;
 332     if ((state & 3) >= 2) {
 333       unsigned int i = state & -4;
 334       unsigned char c;
 335       if (i < 26)
 336         c = i+'A';
 337       else if (i < 52)
 338         c = i-26+'a';
 339       else if (i < 62)
 340         c = i-52+'0';
 341       else if (i == 62)
 342         c = '+';
 343       else if (i == 63)
 344         c = '/';
 345       else
 346         abort();
 347       *r++ = c;
 348     }
 349     *r++ = '-';
 350     /* conv->ostate = 0; will be done by the caller */
 351     return count;
 352   } else
 353     return 0;
 354 }