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init_utils_string.c (3824B)

      1 /*
      2  * Copyright (C) 2004-2005 Kay Sievers <kay.sievers@vrfy.org>
      3  *
      4  *	This program is free software; you can redistribute it and/or modify it
      5  *	under the terms of the GNU General Public License as published by the
      6  *	Free Software Foundation version 2 of the License.
      7  * 
      8  *	This program is distributed in the hope that it will be useful, but
      9  *	WITHOUT ANY WARRANTY; without even the implied warranty of
     10  *	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     11  *	General Public License for more details.
     12  * 
     13  *	You should have received a copy of the GNU General Public License along
     14  *	with this program; if not, write to the Free Software Foundation, Inc.,
     15  *	51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
     16  *
     17  */
     18 
     19 
     20 static void remove_trailing_chars(char *path, char c)
     21 {
     22 	size_t len;
     23 
     24 	len = strlen(path);
     25 	while (len > 0 && path[len-1] == c)
     26 		path[--len] = '\0';
     27 }
     28 
     29 /* count of characters used to encode one unicode char */
     30 static int utf8_encoded_expected_len(const char *str)
     31 {
     32 	unsigned char c = (unsigned char)str[0];
     33 
     34 	if (c < 0x80)
     35 		return 1;
     36 	if ((c & 0xe0) == 0xc0)
     37 		return 2;
     38 	if ((c & 0xf0) == 0xe0)
     39 		return 3;
     40 	if ((c & 0xf8) == 0xf0)
     41 		return 4;
     42 	if ((c & 0xfc) == 0xf8)
     43 		return 5;
     44 	if ((c & 0xfe) == 0xfc)
     45 		return 6;
     46 	return 0;
     47 }
     48 
     49 /* decode one unicode char */
     50 static int utf8_encoded_to_unichar(const char *str)
     51 {
     52 	int unichar;
     53 	int len;
     54 	int i;
     55 
     56 	len = utf8_encoded_expected_len(str);
     57 	switch (len) {
     58 	case 1:
     59 		return (int)str[0];
     60 	case 2:
     61 		unichar = str[0] & 0x1f;
     62 		break;
     63 	case 3:
     64 		unichar = (int)str[0] & 0x0f;
     65 		break;
     66 	case 4:
     67 		unichar = (int)str[0] & 0x07;
     68 		break;
     69 	case 5:
     70 		unichar = (int)str[0] & 0x03;
     71 		break;
     72 	case 6:
     73 		unichar = (int)str[0] & 0x01;
     74 		break;
     75 	default:
     76 		return -1;
     77 	}
     78 
     79 	for (i = 1; i < len; i++) {
     80 		if (((int)str[i] & 0xc0) != 0x80)
     81 			return -1;
     82 		unichar <<= 6;
     83 		unichar |= (int)str[i] & 0x3f;
     84 	}
     85 
     86 	return unichar;
     87 }
     88 
     89 /* expected size used to encode one unicode char */
     90 static int utf8_unichar_to_encoded_len(int unichar)
     91 {
     92 	if (unichar < 0x80)
     93 		return 1;
     94 	if (unichar < 0x800)
     95 		return 2;
     96 	if (unichar < 0x10000)
     97 		return 3;
     98 	if (unichar < 0x200000)
     99 		return 4;
    100 	if (unichar < 0x4000000)
    101 		return 5;
    102 	return 6;
    103 }
    104 
    105 /* check if unicode char has a valid numeric range */
    106 static int utf8_unichar_valid_range(int unichar)
    107 {
    108 	if (unichar > 0x10ffff)
    109 		return 0;
    110 	if ((unichar & 0xfffff800) == 0xd800)
    111 		return 0;
    112 	if ((unichar > 0xfdcf) && (unichar < 0xfdf0))
    113 		return 0;
    114 	if ((unichar & 0xffff) == 0xffff)
    115 		return 0;
    116 	return 1;
    117 }
    118 
    119 /* validate one encoded unicode char and return its length */
    120 static int utf8_encoded_valid_unichar(const char *str)
    121 {
    122 	int len;
    123 	int unichar;
    124 	int i;
    125 
    126 	len = utf8_encoded_expected_len(str);
    127 	if (len == 0)
    128 		return -1;
    129 
    130 	/* ascii is valid */
    131 	if (len == 1)
    132 		return 1;
    133 
    134 	/* check if expected encoded chars are available */
    135 	for (i = 0; i < len; i++)
    136 		if ((str[i] & 0x80) != 0x80)
    137 			return -1;
    138 
    139 	unichar = utf8_encoded_to_unichar(str);
    140 
    141 	/* check if encoded length matches encoded value */
    142 	if (utf8_unichar_to_encoded_len(unichar) != len)
    143 		return -1;
    144 
    145 	/* check if value has valid range */
    146 	if (!utf8_unichar_valid_range(unichar))
    147 		return -1;
    148 
    149 	return len;
    150 }
    151 
    152 /* replace everything but whitelisted plain ascii and valid utf8 */
    153 static int replace_untrusted_chars(char *str)
    154 {
    155 	size_t i = 0;
    156 	int replaced = 0;
    157 
    158 	while (str[i] != '\0') {
    159 		int len;
    160 
    161 		/* valid printable ascii char */
    162 		if ((str[i] >= '0' && str[i] <= '9') ||
    163 		    (str[i] >= 'A' && str[i] <= 'Z') ||
    164 		    (str[i] >= 'a' && str[i] <= 'z') ||
    165 		    strchr(" #$%+-./:=?@_,", str[i])) {
    166 			i++;
    167 			continue;
    168 		}
    169 		/* valid utf8 is accepted */
    170 		len = utf8_encoded_valid_unichar(&str[i]);
    171 		if (len > 1) {
    172 			i += len;
    173 			continue;
    174 		}
    175 
    176 		/* everything else is garbage */
    177 		str[i] = '_';
    178 		i++;
    179 		replaced++;
    180 	}
    181 
    182 	return replaced;
    183 }