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