1 /* 2 * Copyright (c) 1996, 1998 by Internet Software Consortium. 3 * 4 * Permission to use, copy, modify, and distribute this software for any 5 * purpose with or without fee is hereby granted, provided that the above 6 * copyright notice and this permission notice appear in all copies. 7 * 8 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS 9 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES 10 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE 11 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 12 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 13 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 14 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 15 * SOFTWARE. 16 */ 17 18 /* 19 * Portions Copyright (c) 1995 by International Business Machines, Inc. 20 * 21 * International Business Machines, Inc. (hereinafter called IBM) grants 22 * permission under its copyrights to use, copy, modify, and distribute this 23 * Software with or without fee, provided that the above copyright notice and 24 * all paragraphs of this notice appear in all copies, and that the name of IBM 25 * not be used in connection with the marketing of any product incorporating 26 * the Software or modifications thereof, without specific, written prior 27 * permission. 28 * 29 * To the extent it has a right to do so, IBM grants an immunity from suit 30 * under its patents, if any, for the use, sale or manufacture of products to 31 * the extent that such products are used for performing Domain Name System 32 * dynamic updates in TCP/IP networks by means of the Software. No immunity is 33 * granted for any product per se or for any other function of any product. 34 * 35 * THE SOFTWARE IS PROVIDED "AS IS", AND IBM DISCLAIMS ALL WARRANTIES, 36 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A 37 * PARTICULAR PURPOSE. IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL, 38 * DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER ARISING 39 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE, EVEN 40 * IF IBM IS APPRISED OF THE POSSIBILITY OF SUCH DAMAGES. 41 */ 42 #include <ldns/config.h> 43 #include <ctype.h> 44 #include <stdlib.h> 45 #include <string.h> 46 47 static const char Base64[] = 48 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; 49 static const char Pad64 = '='; 50 51 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt) 52 The following encoding technique is taken from RFC 1521 by Borenstein 53 and Freed. It is reproduced here in a slightly edited form for 54 convenience. 55 56 A 65-character subset of US-ASCII is used, enabling 6 bits to be 57 represented per printable character. (The extra 65th character, "=", 58 is used to signify a special processing function.) 59 60 The encoding process represents 24-bit groups of input bits as output 61 strings of 4 encoded characters. Proceeding from left to right, a 62 24-bit input group is formed by concatenating 3 8-bit input groups. 63 These 24 bits are then treated as 4 concatenated 6-bit groups, each 64 of which is translated into a single digit in the base64 alphabet. 65 66 Each 6-bit group is used as an index into an array of 64 printable 67 characters. The character referenced by the index is placed in the 68 output string. 69 70 Table 1: The Base64 Alphabet 71 72 Value Encoding Value Encoding Value Encoding Value Encoding 73 0 A 17 R 34 i 51 z 74 1 B 18 S 35 j 52 0 75 2 C 19 T 36 k 53 1 76 3 D 20 U 37 l 54 2 77 4 E 21 V 38 m 55 3 78 5 F 22 W 39 n 56 4 79 6 G 23 X 40 o 57 5 80 7 H 24 Y 41 p 58 6 81 8 I 25 Z 42 q 59 7 82 9 J 26 a 43 r 60 8 83 10 K 27 b 44 s 61 9 84 11 L 28 c 45 t 62 + 85 12 M 29 d 46 u 63 / 86 13 N 30 e 47 v 87 14 O 31 f 48 w (pad) = 88 15 P 32 g 49 x 89 16 Q 33 h 50 y 90 91 Special processing is performed if fewer than 24 bits are available 92 at the end of the data being encoded. A full encoding quantum is 93 always completed at the end of a quantity. When fewer than 24 input 94 bits are available in an input group, zero bits are added (on the 95 right) to form an integral number of 6-bit groups. Padding at the 96 end of the data is performed using the '=' character. 97 98 Since all base64 input is an integral number of octets, only the 99 ------------------------------------------------- 100 following cases can arise: 101 102 (1) the final quantum of encoding input is an integral 103 multiple of 24 bits; here, the final unit of encoded 104 output will be an integral multiple of 4 characters 105 with no "=" padding, 106 (2) the final quantum of encoding input is exactly 8 bits; 107 here, the final unit of encoded output will be two 108 characters followed by two "=" padding characters, or 109 (3) the final quantum of encoding input is exactly 16 bits; 110 here, the final unit of encoded output will be three 111 characters followed by one "=" padding character. 112 */ 113 114 /* skips all whitespace anywhere. 115 converts characters, four at a time, starting at (or after) 116 src from base - 64 numbers into three 8 bit bytes in the target area. 117 it returns the number of data bytes stored at the target, or -1 on error. 118 */ 119 120 int 121 ldns_b64_pton(char const *src, uint8_t *target, size_t targsize) 122 { 123 int tarindex, state, ch; 124 char *pos; 125 126 state = 0; 127 tarindex = 0; 128 129 if (strlen(src) == 0) { 130 return 0; 131 } 132 133 while ((ch = *src++) != '\0') { 134 if (isspace((unsigned char)ch)) /* Skip whitespace anywhere. */ 135 continue; 136 137 if (ch == Pad64) 138 break; 139 140 pos = strchr(Base64, ch); 141 if (pos == 0) { 142 /* A non-base64 character. */ 143 return (-1); 144 } 145 146 switch (state) { 147 case 0: 148 if (target) { 149 if ((size_t)tarindex >= targsize) 150 return (-1); 151 target[tarindex] = (pos - Base64) << 2; 152 } 153 state = 1; 154 break; 155 case 1: 156 if (target) { 157 if ((size_t)tarindex + 1 >= targsize) 158 return (-1); 159 target[tarindex] |= (pos - Base64) >> 4; 160 target[tarindex+1] = ((pos - Base64) & 0x0f) 161 << 4 ; 162 } 163 tarindex++; 164 state = 2; 165 break; 166 case 2: 167 if (target) { 168 if ((size_t)tarindex + 1 >= targsize) 169 return (-1); 170 target[tarindex] |= (pos - Base64) >> 2; 171 target[tarindex+1] = ((pos - Base64) & 0x03) 172 << 6; 173 } 174 tarindex++; 175 state = 3; 176 break; 177 case 3: 178 if (target) { 179 if ((size_t)tarindex >= targsize) 180 return (-1); 181 target[tarindex] |= (pos - Base64); 182 } 183 tarindex++; 184 state = 0; 185 break; 186 default: 187 abort(); 188 } 189 } 190 191 /* 192 * We are done decoding Base-64 chars. Let's see if we ended 193 * on a byte boundary, and/or with erroneous trailing characters. 194 */ 195 196 if (ch == Pad64) { /* We got a pad char. */ 197 ch = *src++; /* Skip it, get next. */ 198 switch (state) { 199 case 0: /* Invalid = in first position */ 200 case 1: /* Invalid = in second position */ 201 return (-1); 202 203 case 2: /* Valid, means one byte of info */ 204 /* Skip any number of spaces. */ 205 for ((void)NULL; ch != '\0'; ch = *src++) 206 if (!isspace((unsigned char)ch)) 207 break; 208 /* Make sure there is another trailing = sign. */ 209 if (ch != Pad64) 210 return (-1); 211 ch = *src++; /* Skip the = */ 212 /* Fall through to "single trailing =" case. */ 213 /* FALLTHROUGH */ 214 215 case 3: /* Valid, means two bytes of info */ 216 /* 217 * We know this char is an =. Is there anything but 218 * whitespace after it? 219 */ 220 for ((void)NULL; ch != '\0'; ch = *src++) 221 if (!isspace((unsigned char)ch)) 222 return (-1); 223 224 /* 225 * Now make sure for cases 2 and 3 that the "extra" 226 * bits that slopped past the last full byte were 227 * zeros. If we don't check them, they become a 228 * subliminal channel. 229 */ 230 if (target && target[tarindex] != 0) 231 return (-1); 232 } 233 } else { 234 /* 235 * We ended by seeing the end of the string. Make sure we 236 * have no partial bytes lying around. 237 */ 238 if (state != 0) 239 return (-1); 240 } 241 242 return (tarindex); 243 } 244