1 /*
2 * rfc2047.c -- decode RFC-2047 header format
3 */
4
5 #pragma ident "%Z%%M% %I% %E% SMI"
6
7 #ifndef lint
8 static char sccsi2[] = "%W% (Sun) %G%";
9 #endif
10
11 /*
12 * Copyright (c) 1997-1998 Richard Coleman
13 * All rights reserved.
14 *
15 * Permission is hereby granted, without written agreement and without
16 * license or royalty fees, to use, copy, modify, and distribute this
17 * software and to distribute modified versions of this software for any
18 * purpose, provided that the above copyright notice and the following two
19 * paragraphs appear in all copies of this software.
20 *
21 * In no event shall Richard Coleman be liable to any party for direct,
22 * indirect, special, incidental, or consequential damages arising out of
23 * the use of this software and its documentation, even if Richard Coleman
24 * has been advised of the possibility of such damage.
25 *
26 * Richard Coleman specifically disclaims any warranties, including, but
27 * not limited to, the implied warranties of merchantability and fitness
28 * for a particular purpose. The software provided hereunder is on an "as
29 * is" basis, and Richard Coleman has no obligation to provide maintenance,
30 * support, updates, enhancements, or modifications.
31 */
32
33 /*
34 * Parts of this code were derived from metamail, which is ...
35 *
36 * Copyright (c) 1991 Bell Communications Research, Inc. (Bellcore)
37 *
38 * Permission to use, copy, modify, and distribute this material
39 * for any purpose and without fee is hereby granted, provided
40 * that the above copyright notice and this permission notice
41 * appear in all copies, and that the name of Bellcore not be
42 * used in advertising or publicity pertaining to this
43 * material without the specific, prior written permission
44 * of an authorized representative of Bellcore. BELLCORE
45 * MAKES NO REPRESENTATIONS ABOUT THE ACCURACY OR SUITABILITY
46 * OF THIS MATERIAL FOR ANY PURPOSE. IT IS PROVIDED "AS IS",
47 * WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES.
48 */
49
50 /*
51 * Copyright (c) 1998, by Sun Microsystems, Inc.
52 * All rights reserved.
53 */
54
55 #include <string.h>
56
57 typedef int bool;
58
59 #define FALSE 0
60 #define TRUE 1
61
62 static signed char hexindex[] = {
63 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
64 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
65 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
66 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1,
67 -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
68 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
69 -1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1,
70 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1
71 };
72
73 static signed char index_64[128] = {
74 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
75 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
76 -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
77 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
78 -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
79 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,
80 -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,
81 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1
82 };
83
84 #define char64(c) (((unsigned char) (c) > 127) ? -1 : \
85 index_64[(unsigned char) (c)])
86
87 static int
unqp(unsigned char byte1,unsigned char byte2)88 unqp(unsigned char byte1, unsigned char byte2)
89 {
90 if (hexindex[byte1] == -1 || hexindex[byte2] == -1)
91 return (-1);
92 return (hexindex[byte1] << 4 | hexindex[byte2]);
93 }
94
95 /* Check if character is linear whitespace */
96 #define is_lws(c) ((c) == ' ' || (c) == '\t' || (c) == '\n')
97
98 /*
99 * Decode the string as a RFC-2047 header field
100 */
101
102 bool
decode_rfc2047(char * str,char * dst,char * charset)103 decode_rfc2047(char *str, char *dst, char *charset)
104 {
105 char *p, *q, *pp;
106 char *startofmime, *endofmime;
107 int c, quoted_printable;
108 bool encoding_found = FALSE; /* did we decode anything? */
109 bool between_encodings = FALSE; /* are we between two encodings? */
110 bool equals_pending = FALSE; /* is there a '=' pending? */
111 int whitespace = 0; /* how much whitespace between encodings? */
112
113 if (str == NULL)
114 return (FALSE);
115
116 /*
117 * Do a quick and dirty check for the '=' character.
118 * This should quickly eliminate many cases.
119 */
120 if (!strchr(str, '='))
121 return (FALSE);
122
123 for (p = str, q = dst; *p; p++) {
124 /*
125 * If we had an '=' character pending from
126 * last iteration, then add it first.
127 */
128 if (equals_pending) {
129 *q++ = '=';
130 equals_pending = FALSE;
131 between_encodings = FALSE; /* we added non-WS text */
132 }
133
134 if (*p != '=') {
135 /* count linear whitespace while between encodings */
136 if (between_encodings && is_lws(*p))
137 whitespace++;
138 else
139 between_encodings = FALSE; /* non-WS added */
140 *q++ = *p;
141 continue;
142 }
143
144 equals_pending = TRUE; /* we have a '=' pending */
145
146 /* Check for initial =? */
147 if (*p == '=' && p[1] && p[1] == '?' && p[2]) {
148 startofmime = p + 2;
149
150 /* Scan ahead for the next '?' character */
151 for (pp = startofmime; *pp && *pp != '?'; pp++)
152 ;
153
154 if (!*pp)
155 continue;
156
157 strncpy(charset, startofmime, pp - startofmime);
158 charset[pp - startofmime] = '\0';
159
160 startofmime = pp + 1;
161
162 /* Check for valid encoding type */
163 if (*startofmime != 'B' && *startofmime != 'b' &&
164 *startofmime != 'Q' && *startofmime != 'q')
165 continue;
166
167 /* Is encoding quoted printable or base64? */
168 quoted_printable = (*startofmime == 'Q' ||
169 *startofmime == 'q');
170 startofmime++;
171
172 /* Check for next '?' character */
173 if (*startofmime != '?')
174 continue;
175 startofmime++;
176
177 /*
178 * Scan ahead for the ending ?=
179 *
180 * While doing this, we will also check if encoded
181 * word has any embedded linear whitespace.
182 */
183 endofmime = NULL;
184 for (pp = startofmime; *pp && *(pp+1); pp++) {
185 if (is_lws(*pp))
186 break;
187 else if (*pp == '?' && pp[1] == '=') {
188 endofmime = pp;
189 break;
190 }
191 }
192 if (is_lws(*pp) || endofmime == NULL)
193 continue;
194
195 /*
196 * We've found an encoded word, so we can drop
197 * the '=' that was pending
198 */
199 equals_pending = FALSE;
200
201 /*
202 * If we are between two encoded words separated only
203 * by linear whitespace, then we ignore the whitespace.
204 * We will roll back the buffer the number of whitespace
205 * characters we've seen since last encoded word.
206 */
207 if (between_encodings)
208 q -= whitespace;
209
210 /* Now decode the text */
211 if (quoted_printable) {
212 for (pp = startofmime; pp < endofmime; pp++) {
213 if (*pp == '=') {
214 c = unqp(pp[1], pp[2]);
215 if (c == -1)
216 continue;
217 if (c != 0)
218 *q++ = c;
219 pp += 2;
220 } else if (*pp == '_')
221 *q++ = ' ';
222 else
223 *q++ = *pp;
224 }
225 } else {
226 /* base64 */
227 int c1, c2, c3, c4;
228
229 pp = startofmime;
230 while (pp < endofmime) {
231 /* 6 + 2 bits */
232 while ((pp < endofmime) &&
233 ((c1 = char64(*pp)) == -1)) {
234 pp++;
235 }
236 if (pp < endofmime)
237 pp++;
238 while ((pp < endofmime) &&
239 ((c2 = char64(*pp)) == -1)) {
240 pp++;
241 }
242 if (pp < endofmime && c1 != -1 &&
243 c2 != -1) {
244 *q++ = (c1 << 2) | (c2 >> 4);
245 pp++;
246 }
247 /* 4 + 4 bits */
248 while ((pp < endofmime) &&
249 ((c3 = char64(*pp)) == -1)) {
250 pp++;
251 }
252 if (pp < endofmime && c2 != -1 &&
253 c3 != -1) {
254 *q++ = ((c2 & 0xF) << 4) |
255 (c3 >> 2);
256 pp++;
257 }
258 /* 2 + 6 bits */
259 while ((pp < endofmime) &&
260 ((c4 = char64(*pp)) == -1)) {
261 pp++;
262 }
263 if (pp < endofmime && c3 != -1 &&
264 c4 != -1) {
265 *q++ = ((c3 & 0x3) << 6) | (c4);
266 pp++;
267 }
268 }
269 }
270
271 /*
272 * Now that we are done decoding this particular
273 * encoded word, advance string to trailing '='.
274 */
275 p = endofmime + 1;
276
277 encoding_found = TRUE; /* found (>= 1) encoded word */
278 between_encodings = TRUE; /* just decoded something */
279 whitespace = 0; /* re-initialize amount of whitespace */
280 }
281 }
282
283 /* If an equals was pending at end of string, add it now. */
284 if (equals_pending)
285 *q++ = '=';
286 *q = '\0';
287
288 return (encoding_found);
289 }
290