1/* 2 * rfc2047.c -- decode RFC-2047 header format 3 */ 4 5#pragma ident "%Z%%M% %I% %E% SMI" 6 7#ifndef lint 8static 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 57typedef int bool; 58 59#define FALSE 0 60#define TRUE 1 61 62static 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 73static 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 87static int 88unqp(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 102bool 103decode_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