c6d25d8d |
1 | /* |
2 | * utf7.c - routines to handle UTF-7 (RFC 1642 / RFC 2152). |
3 | */ |
4 | |
5 | #ifndef ENUM_CHARSETS |
6 | |
7 | #include "charset.h" |
8 | #include "internal.h" |
9 | |
10 | /* |
11 | * This array is generated by a piece of Perl: |
12 | |
13 | perl -e 'for $i (0..32) { $a[$i] |= 2; } $a[32] |= 1;' \ |
14 | -e 'for $i ("a".."z","A".."Z","0".."9","'\''","(",' \ |
15 | -e ' ")",",","-",".","/",":","?") { $a[ord $i] |= 1; }' \ |
16 | -e 'for $i ("!","\"","#","\$","%","&","*",";","<","=",">","\@",' \ |
17 | -e ' "[","]","^","_","`","{","|","}") { $a[ord $i] |= 2; }' \ |
18 | -e 'for $i ("a".."z","A".."Z","0".."9","+","/") { $a[ord $i] |= 4; }' \ |
19 | -e 'for $i (0..127) { printf "%s%d,%s", $i%32?"":" ", $a[$i],' \ |
20 | -e ' ($i+1)%32?"":"\n"; }' |
21 | |
22 | */ |
23 | static const unsigned char utf7_ascii_properties[128] = { |
24 | 2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2, |
25 | 3,2,2,2,2,2,2,1,1,1,2,4,1,1,1,5,5,5,5,5,5,5,5,5,5,5,1,2,2,2,2,1, |
26 | 2,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,2,0,2,2,2, |
27 | 2,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,2,2,2,0,0, |
28 | }; |
29 | #define SET_D(c) ((c) >= 0 && (c) < 0x80 && (utf7_ascii_properties[(c)] & 1)) |
30 | #define SET_O(c) ((c) >= 0 && (c) < 0x80 && (utf7_ascii_properties[(c)] & 2)) |
31 | #define SET_B(c) ((c) >= 0 && (c) < 0x80 && (utf7_ascii_properties[(c)] & 4)) |
32 | |
33 | #define base64_value(c) ( (c) >= 'A' && (c) <= 'Z' ? (c) - 'A' : \ |
34 | (c) >= 'a' && (c) <= 'z' ? (c) - 'a' + 26 : \ |
35 | (c) >= '0' && (c) <= '9' ? (c) - '0' + 52 : \ |
36 | (c) == '+' ? 62 : 63 ) |
37 | |
8bade113 |
38 | static const char *const base64_chars = |
c6d25d8d |
39 | "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; |
40 | |
41 | static void read_utf7(charset_spec const *charset, long int input_chr, |
42 | charset_state *state, |
43 | void (*emit)(void *ctx, long int output), void *emitctx) |
44 | { |
45 | long int hw; |
46 | |
47 | UNUSEDARG(charset); |
48 | |
49 | /* |
50 | * state->s0 is used to handle the conversion of the UTF-7 |
51 | * transport format into a stream of halfwords. Its layout is: |
52 | * |
53 | * - In normal ASCII mode, it is zero. |
54 | * |
55 | * - Otherwise, it holds a leading 1 followed by all the bits |
56 | * so far accumulated in base64 digits. |
57 | * |
58 | * - Special case: when we have only just seen the initial `+' |
59 | * which enters base64 mode, it is set to 2 rather than 1 |
60 | * (this is an otherwise unused value since base64 always |
61 | * accumulates an even number of bits at a time), so that |
62 | * the special sequence `+-' can be made to encode `+' |
63 | * easily. |
64 | * |
65 | * state->s1 is used to handle the conversion of those |
66 | * halfwords into Unicode values. It contains a high surrogate |
67 | * value if we've just seen one, and 0 otherwise. |
68 | */ |
69 | |
70 | if (!state->s0) { |
71 | if (input_chr == '+') |
72 | state->s0 = 2; |
73 | else |
74 | emit(emitctx, input_chr); |
75 | return; |
76 | } else { |
77 | if (!SET_B(input_chr)) { |
78 | /* |
79 | * base64 mode ends here. Emit the character we have, |
80 | * unless it's a minus in which case we should swallow |
81 | * it. |
82 | */ |
83 | if (input_chr != '-') |
84 | emit(emitctx, input_chr); |
85 | else if (state->s0 == 2) |
86 | emit(emitctx, '+'); /* special case */ |
87 | state->s0 = 0; |
88 | return; |
89 | } |
90 | |
91 | /* |
92 | * Now we have a base64 character, so add it to our state, |
93 | * first correcting the special case value of s0. |
94 | */ |
95 | if (state->s0 == 2) |
96 | state->s0 = 1; |
97 | state->s0 = (state->s0 << 6) | base64_value(input_chr); |
98 | } |
99 | |
100 | /* |
101 | * If we don't have a whole halfword at this point, bale out. |
102 | */ |
103 | if (!(state->s0 & 0xFFFF0000)) |
104 | return; |
105 | |
106 | /* |
107 | * Otherwise, extract the halfword. There are three |
108 | * possibilities for where the top set bit might be. |
109 | */ |
110 | if (state->s0 & 0x00100000) { |
111 | hw = (state->s0 >> 4) & 0xFFFF; |
112 | state->s0 = (state->s0 & 0xF) | 0x10; |
113 | } else if (state->s0 & 0x00040000) { |
114 | hw = (state->s0 >> 2) & 0xFFFF; |
115 | state->s0 = (state->s0 & 3) | 4; |
116 | } else { |
117 | hw = state->s0 & 0xFFFF; |
118 | state->s0 = 1; |
119 | } |
120 | |
121 | /* |
122 | * Now what reaches this point should be a stream of halfwords |
123 | * in sensible numeric form. So now we process surrogates. |
124 | */ |
125 | if (state->s1) { |
126 | /* |
127 | * We have already seen a high surrogate, so we expect a |
128 | * low surrogate. Whinge if we didn't get it. |
129 | */ |
130 | if (hw < 0xDC00 || hw >= 0xE000) { |
131 | emit(emitctx, ERROR); |
132 | } else { |
133 | hw &= 0x3FF; |
134 | hw |= (state->s1 & 0x3FF) << 10; |
135 | emit(emitctx, hw + 0x10000); |
136 | } |
137 | state->s1 = 0; |
138 | } else { |
139 | /* |
140 | * Any low surrogate is an error. |
141 | */ |
142 | if (hw >= 0xDC00 && hw < 0xE000) { |
143 | emit(emitctx, ERROR); |
144 | return; |
145 | } |
146 | |
147 | /* |
148 | * Any high surrogate is simply stored until we see the |
149 | * next halfword. |
150 | */ |
151 | if (hw >= 0xD800 && hw < 0xDC00) { |
152 | state->s1 = hw; |
153 | return; |
154 | } |
155 | |
156 | /* |
157 | * Anything else we simply output. |
158 | */ |
159 | emit(emitctx, hw); |
160 | } |
161 | } |
162 | |
163 | /* |
164 | * For writing UTF-7, we supply two charset definitions, one of |
165 | * which will directly encode Set O characters and the other of |
166 | * which will cautiously base64 them. |
167 | */ |
168 | static int write_utf7(charset_spec const *charset, long int input_chr, |
169 | charset_state *state, |
170 | void (*emit)(void *ctx, long int output), |
171 | void *emitctx) |
172 | { |
173 | unsigned long hws[2]; |
174 | int nhws; |
175 | int i; |
176 | |
177 | /* |
178 | * For writing: state->s0 contains accumulated base64 data with |
179 | * a 1 in front, and state->s1 indicates how many bits of it we |
180 | * have. |
181 | */ |
182 | |
183 | if ((input_chr >= 0xD800 && input_chr < 0xE000) || |
184 | input_chr >= 0x110000) { |
185 | /* |
186 | * We can't output surrogates, or anything above 0x10FFFF. |
187 | */ |
188 | return FALSE; |
189 | } |
190 | |
191 | /* |
192 | * Look for characters which we output in ASCII mode. A special |
193 | * case here is +, which can be encoded as the empty base64 |
194 | * escape sequence `+-': if we're _already_ in ASCII mode we do |
195 | * that, but if we're in base64 mode at the point we see the + |
196 | * then we simply stay in base64 mode and output it as a |
197 | * halfword. (Switching back would cost three bytes, whereas |
198 | * staying in base64 costs only 2 2/3.) |
199 | */ |
200 | if (input_chr == -1 || SET_D(input_chr) || |
201 | (charset->charset == CS_UTF7 && SET_O(input_chr)) || |
202 | (!state->s0 && input_chr == '+')) { |
203 | if (state->s0) { |
204 | /* |
205 | * These characters are output in ASCII mode, so flush any |
206 | * lingering base64 data. |
207 | */ |
208 | state->s0 <<= 6 - state->s1; |
209 | emit(emitctx, base64_chars[state->s0 & 0x3F]); |
210 | /* |
211 | * I'm going to arbitrarily decide to always use the |
212 | * terminating minus sign. It's easier than figuring out |
213 | * whether to do so or not, and looks prettier besides. |
214 | */ |
215 | emit(emitctx, '-'); |
216 | state->s0 = state->s1 = 0; |
217 | } |
218 | |
219 | /* |
220 | * Now output the character. |
221 | */ |
222 | if (input_chr != -1) /* special case: just reset state */ |
223 | emit(emitctx, input_chr); |
224 | if (input_chr == '+') |
225 | emit(emitctx, '-'); /* +- encodes + */ |
226 | return TRUE; |
227 | } |
228 | |
229 | /* |
230 | * Now we know we have a character that needs to be output as |
231 | * either one base64-encoded halfword or two. So first figure |
232 | * out how many... |
233 | */ |
234 | if (input_chr < 0x10000) { |
235 | nhws = 1; |
236 | hws[0] = input_chr; |
237 | } else { |
238 | input_chr -= 0x10000; |
239 | if (input_chr >= 0x100000) { |
240 | /* Anything above 0x10FFFF is outside UTF-7 range. */ |
241 | return FALSE; |
242 | } |
243 | |
244 | nhws = 2; |
245 | hws[0] = 0xD800 | ((input_chr >> 10) & 0x3FF); |
246 | hws[1] = 0xDC00 | (input_chr & 0x3FF); |
247 | } |
248 | |
249 | /* |
250 | * ... switch into base64 mode if required ... |
251 | */ |
252 | if (!state->s0) { |
253 | emit(emitctx, '+'); |
254 | state->s0 = 1; |
255 | state->s1 = 0; |
256 | } |
257 | |
258 | /* |
259 | * ... and do the base64 output. |
260 | */ |
261 | for (i = 0; i < nhws; i++) { |
262 | state->s0 = (state->s0 << 16) | hws[i]; |
263 | state->s1 += 16; |
264 | |
265 | while (state->s1 >= 6) { |
266 | /* |
267 | * The top set bit must be in position 16, 18 or 20. |
268 | */ |
269 | unsigned long out, topbit; |
270 | |
271 | out = (state->s0 >> (state->s1 - 6)) & 0x3F; |
272 | state->s1 -= 6; |
273 | topbit = 1 << state->s1; |
274 | state->s0 = (state->s0 & (topbit-1)) | topbit; |
275 | |
276 | emit(emitctx, base64_chars[out]); |
277 | } |
278 | } |
279 | return TRUE; |
280 | } |
281 | |
282 | const charset_spec charset_CS_UTF7 = { |
283 | CS_UTF7, read_utf7, write_utf7, NULL |
284 | }; |
285 | |
286 | const charset_spec charset_CS_UTF7_CONSERVATIVE = { |
287 | CS_UTF7_CONSERVATIVE, read_utf7, write_utf7, NULL |
288 | }; |
289 | |
290 | #else /* ENUM_CHARSETS */ |
291 | |
292 | ENUM_CHARSET(CS_UTF7) |
293 | ENUM_CHARSET(CS_UTF7_CONSERVATIVE) |
294 | |
295 | #endif /* ENUM_CHARSETS */ |