1/*
2 * Copyright (C) 1999-2001, 2008 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 Library General Public
7 * License as published by the Free Software Foundation; either version 2
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 * Library General Public License for more details.
14 *
15 * You should have received a copy of the GNU Library General Public
16 * License along with the GNU LIBICONV Library; see the file COPYING.LIB.
17 * If not, write to the Free Software Foundation, Inc., 51 Franklin Street,
18 * Fifth Floor, Boston, MA 02110-1301, USA.
19 */
20
21/*
22 * UTF-7
23 */
24
25/* Specification: RFC 2152 (and old RFC 1641, RFC 1642) */
26/* The original Base64 encoding is defined in RFC 2045. */
27
28/* Set of direct characters:
29 *   A-Z a-z 0-9 ' ( ) , - . / : ? space tab lf cr
30 */
31static const unsigned char direct_tab[128/8] = {
32  0x00, 0x26, 0x00, 0x00, 0x81, 0xf3, 0xff, 0x87,
33  0xfe, 0xff, 0xff, 0x07, 0xfe, 0xff, 0xff, 0x07,
34};
35#define isdirect(ch) ((ch) < 128 && ((direct_tab[(ch)>>3] >> (ch & 7)) & 1))
36
37/* Set of direct and optional direct characters:
38 *   A-Z a-z 0-9 ' ( ) , - . / : ? space tab lf cr
39 *   ! " # $ % & * ; < = > @ [ ] ^ _ ` { | }
40 */
41static const unsigned char xdirect_tab[128/8] = {
42  0x00, 0x26, 0x00, 0x00, 0xff, 0xf7, 0xff, 0xff,
43  0xff, 0xff, 0xff, 0xef, 0xff, 0xff, 0xff, 0x3f,
44};
45#define isxdirect(ch) ((ch) < 128 && ((xdirect_tab[(ch)>>3] >> (ch & 7)) & 1))
46
47/* Set of base64 characters, extended:
48 *   A-Z a-z 0-9 + / -
49 */
50static const unsigned char xbase64_tab[128/8] = {
51  0x00, 0x00, 0x00, 0x00, 0x00, 0xa8, 0xff, 0x03,
52  0xfe, 0xff, 0xff, 0x07, 0xfe, 0xff, 0xff, 0x07,
53};
54#define isxbase64(ch) ((ch) < 128 && ((xbase64_tab[(ch)>>3] >> (ch & 7)) & 1))
55
56/*
57 * The state is structured as follows:
58 * bit 1..0: shift
59 * bit 7..2: data
60 * Precise meaning:
61 *   shift      data
62 *     0         0           not inside base64 encoding
63 *     1         0           inside base64, no pending bits
64 *     2      XXXX00         inside base64, 4 bits remain from 2nd byte
65 *     3      XX0000         inside base64, 2 bits remain from 3rd byte
66 */
67
68static int
69utf7_mbtowc (conv_t conv, ucs4_t *pwc, const unsigned char *s, int n)
70{
71  state_t state = conv->istate;
72  int count = 0; /* number of input bytes already read */
73  if (state & 3)
74    goto active;
75  else
76    goto inactive;
77
78inactive:
79  {
80    /* Here (state & 3) == 0 */
81    if (n < count+1)
82      goto none;
83    {
84      unsigned char c = *s;
85      if (isxdirect(c)) {
86        *pwc = (ucs4_t) c;
87        conv->istate = state;
88        return count+1;
89      }
90      if (c == '+') {
91        if (n < count+2)
92          goto none;
93        if (s[1] == '-') {
94          *pwc = (ucs4_t) '+';
95          conv->istate = state;
96          return count+2;
97        }
98        s++; count++;
99        state = 1;
100        goto active;
101      }
102      goto ilseq;
103    }
104  }
105
106active:
107  {
108    /* base64 encoding active */
109    unsigned int wc = 0;
110    state_t base64state = state;
111    unsigned int kmax = 2; /* number of payload bytes to read */
112    unsigned int k = 0; /* number of payload bytes already read */
113    unsigned int base64count = 0; /* number of base64 bytes already read */
114    for (;;) {
115      unsigned char c = *s;
116      unsigned int i;
117      if (c >= 'A' && c <= 'Z')
118        i = c-'A';
119      else if (c >= 'a' && c <= 'z')
120        i = c-'a'+26;
121      else if (c >= '0' && c <= '9')
122        i = c-'0'+52;
123      else if (c == '+')
124        i = 62;
125      else if (c == '/')
126        i = 63;
127      else {
128        /* c terminates base64 encoding */
129        if (base64state & -4)
130          goto ilseq; /* data must be 0, otherwise illegal */
131        if (base64count)
132          goto ilseq; /* partial UTF-16 characters are invalid */
133        if (c == '-') {
134          s++; count++;
135        }
136        state = 0;
137        goto inactive;
138      }
139      s++; base64count++;
140      /* read 6 bits: 0 <= i < 64 */
141      switch (base64state & 3) {
142        case 1: /* inside base64, no pending bits */
143          base64state = (i << 2) | 0; break;
144        case 0: /* inside base64, 6 bits remain from 1st byte */
145          wc = (wc << 8) | (base64state & -4) | (i >> 4); k++;
146          base64state = ((i & 15) << 4) | 2; break;
147        case 2: /* inside base64, 4 bits remain from 2nd byte */
148          wc = (wc << 8) | (base64state & -4) | (i >> 2); k++;
149          base64state = ((i & 3) << 6) | 3; break;
150        case 3: /* inside base64, 2 bits remain from 3rd byte */
151          wc = (wc << 8) | (base64state & -4) | i; k++;
152          base64state = 1; break;
153      }
154      if (k == kmax) {
155        /* UTF-16: When we see a High Surrogate, we must also decode
156           the following Low Surrogate. */
157        if (kmax == 2 && (wc >= 0xd800 && wc < 0xdc00))
158          kmax = 4;
159        else
160          break;
161      }
162      if (n < count+base64count+1)
163        goto none;
164    }
165    /* Here k = kmax > 0, hence base64count > 0. */
166    if ((base64state & 3) == 0) abort();
167    if (kmax == 4) {
168      ucs4_t wc1 = wc >> 16;
169      ucs4_t wc2 = wc & 0xffff;
170      if (!(wc1 >= 0xd800 && wc1 < 0xdc00)) abort();
171      if (!(wc2 >= 0xdc00 && wc2 < 0xe000)) goto ilseq;
172      *pwc = 0x10000 + ((wc1 - 0xd800) << 10) + (wc2 - 0xdc00);
173    } else {
174      *pwc = wc;
175    }
176    conv->istate = base64state;
177    return count+base64count;
178  }
179
180none:
181  conv->istate = state;
182  return RET_TOOFEW(count);
183
184ilseq:
185  conv->istate = state;
186  return RET_SHIFT_ILSEQ(count);
187}
188
189/*
190 * The state is structured as follows:
191 * bit 1..0: shift
192 * bit 7..2: data
193 * Precise meaning:
194 *   shift      data
195 *     0         0           not inside base64 encoding
196 *     1         0           inside base64, no pending bits
197 *     2       XX00          inside base64, 2 bits known for 2nd byte
198 *     3       XXXX          inside base64, 4 bits known for 3rd byte
199 */
200
201/* Define this to 1 if you want the so-called "optional direct" characters
202      ! " # $ % & * ; < = > @ [ ] ^ _ ` { | }
203   to be encoded. Define to 0 if you want them to be passed straight through,
204   like the so-called "direct" characters.
205   We set this to 1 because it's safer.
206 */
207#define UTF7_ENCODE_OPTIONAL_CHARS 1
208
209static int
210utf7_wctomb (conv_t conv, unsigned char *r, ucs4_t iwc, int n)
211{
212  state_t state = conv->ostate;
213  unsigned int wc = iwc;
214  int count = 0;
215  if (state & 3)
216    goto active;
217
218/*inactive:*/
219  {
220    if (UTF7_ENCODE_OPTIONAL_CHARS ? isdirect(wc) : isxdirect(wc)) {
221      r[0] = (unsigned char) wc;
222      /*conv->ostate = state;*/
223      return 1;
224    } else {
225      *r++ = '+';
226      if (wc == '+') {
227        if (n < 2)
228          return RET_TOOSMALL;
229        *r = '-';
230        /*conv->ostate = state;*/
231        return 2;
232      }
233      count = 1;
234      state = 1;
235      goto active;
236    }
237  }
238
239active:
240  {
241    /* base64 encoding active */
242    if (UTF7_ENCODE_OPTIONAL_CHARS ? isdirect(wc) : isxdirect(wc)) {
243      /* deactivate base64 encoding */
244      count += ((state & 3) >= 2 ? 1 : 0) + (isxbase64(wc) ? 1 : 0) + 1;
245      if (n < count)
246        return RET_TOOSMALL;
247      if ((state & 3) >= 2) {
248        unsigned int i = state & -4;
249        unsigned char c;
250        if (i < 26)
251          c = i+'A';
252        else if (i < 52)
253          c = i-26+'a';
254        else if (i < 62)
255          c = i-52+'0';
256        else if (i == 62)
257          c = '+';
258        else if (i == 63)
259          c = '/';
260        else
261          abort();
262        *r++ = c;
263      }
264      if (isxbase64(wc))
265        *r++ = '-';
266      state = 0;
267      *r++ = (unsigned char) wc;
268      conv->ostate = state;
269      return count;
270    } else {
271      unsigned int k; /* number of payload bytes to write */
272      if (wc < 0x10000) {
273        k = 2;
274        count += ((state & 3) >= 2 ? 3 : 2);
275      } else if (wc < 0x110000) {
276        unsigned int wc1 = 0xd800 + ((wc - 0x10000) >> 10);
277        unsigned int wc2 = 0xdc00 + ((wc - 0x10000) & 0x3ff);
278        wc = (wc1 << 16) | wc2;
279        k = 4;
280        count += ((state & 3) >= 3 ? 6 : 5);
281      } else
282        return RET_ILUNI;
283      if (n < count)
284        return RET_TOOSMALL;
285      for (;;) {
286        unsigned int i;
287        unsigned char c;
288        switch (state & 3) {
289          case 0: /* inside base64, 6 bits known for 4th byte */
290            c = (state & -4) >> 2; state = 1; break;
291          case 1: /* inside base64, no pending bits */
292            i = (wc >> (8 * --k)) & 0xff;
293            c = i >> 2; state = ((i & 3) << 4) | 2; break;
294          case 2: /* inside base64, 2 bits known for 2nd byte */
295            i = (wc >> (8 * --k)) & 0xff;
296            c = (state & -4) | (i >> 4); state = ((i & 15) << 2) | 3; break;
297          case 3: /* inside base64, 4 bits known for 3rd byte */
298            i = (wc >> (8 * --k)) & 0xff;
299            c = (state & -4) | (i >> 6); state = ((i & 63) << 2) | 0; break;
300          default: abort(); /* stupid gcc */
301        }
302        if (c < 26)
303          c = c+'A';
304        else if (c < 52)
305          c = c-26+'a';
306        else if (c < 62)
307          c = c-52+'0';
308        else if (c == 62)
309          c = '+';
310        else if (c == 63)
311          c = '/';
312        else
313          abort();
314        *r++ = c;
315        if ((state & 3) && (k == 0))
316          break;
317      }
318      conv->ostate = state;
319      return count;
320    }
321  }
322}
323
324static int
325utf7_reset (conv_t conv, unsigned char *r, int n)
326{
327  state_t state = conv->ostate;
328  if (state & 3) {
329    /* deactivate base64 encoding */
330    unsigned int count = ((state & 3) >= 2 ? 1 : 0) + 1;
331    if (n < count)
332      return RET_TOOSMALL;
333    if ((state & 3) >= 2) {
334      unsigned int i = state & -4;
335      unsigned char c;
336      if (i < 26)
337        c = i+'A';
338      else if (i < 52)
339        c = i-26+'a';
340      else if (i < 62)
341        c = i-52+'0';
342      else if (i == 62)
343        c = '+';
344      else if (i == 63)
345        c = '/';
346      else
347        abort();
348      *r++ = c;
349    }
350    *r++ = '-';
351    /* conv->ostate = 0; will be done by the caller */
352    return count;
353  } else
354    return 0;
355}
356