b64_ntop.c (7373B)
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 <config.h> 43 44 #include <sys/types.h> 45 #include <sys/param.h> 46 #include <sys/socket.h> 47 48 #include <netinet/in.h> 49 #include <arpa/inet.h> 50 51 #include <ctype.h> 52 #include <stdio.h> 53 #include <stdlib.h> 54 #include <string.h> 55 56 #include "fdm.h" 57 58 #define Assert(Cond) if (!(Cond)) abort() 59 60 static const char Base64[] = 61 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; 62 static const char Pad64 = '='; 63 64 /* (From RFC1521 and draft-ietf-dnssec-secext-03.txt) 65 The following encoding technique is taken from RFC 1521 by Borenstein 66 and Freed. It is reproduced here in a slightly edited form for 67 convenience. 68 69 A 65-character subset of US-ASCII is used, enabling 6 bits to be 70 represented per printable character. (The extra 65th character, "=", 71 is used to signify a special processing function.) 72 73 The encoding process represents 24-bit groups of input bits as output 74 strings of 4 encoded characters. Proceeding from left to right, a 75 24-bit input group is formed by concatenating 3 8-bit input groups. 76 These 24 bits are then treated as 4 concatenated 6-bit groups, each 77 of which is translated into a single digit in the base64 alphabet. 78 79 Each 6-bit group is used as an index into an array of 64 printable 80 characters. The character referenced by the index is placed in the 81 output string. 82 83 Table 1: The Base64 Alphabet 84 85 Value Encoding Value Encoding Value Encoding Value Encoding 86 0 A 17 R 34 i 51 z 87 1 B 18 S 35 j 52 0 88 2 C 19 T 36 k 53 1 89 3 D 20 U 37 l 54 2 90 4 E 21 V 38 m 55 3 91 5 F 22 W 39 n 56 4 92 6 G 23 X 40 o 57 5 93 7 H 24 Y 41 p 58 6 94 8 I 25 Z 42 q 59 7 95 9 J 26 a 43 r 60 8 96 10 K 27 b 44 s 61 9 97 11 L 28 c 45 t 62 + 98 12 M 29 d 46 u 63 / 99 13 N 30 e 47 v 100 14 O 31 f 48 w (pad) = 101 15 P 32 g 49 x 102 16 Q 33 h 50 y 103 104 Special processing is performed if fewer than 24 bits are available 105 at the end of the data being encoded. A full encoding quantum is 106 always completed at the end of a quantity. When fewer than 24 input 107 bits are available in an input group, zero bits are added (on the 108 right) to form an integral number of 6-bit groups. Padding at the 109 end of the data is performed using the '=' character. 110 111 Since all base64 input is an integral number of octets, only the 112 following cases can arise: 113 114 (1) the final quantum of encoding input is an integral 115 multiple of 24 bits; here, the final unit of encoded 116 output will be an integral multiple of 4 characters 117 with no "=" padding, 118 (2) the final quantum of encoding input is exactly 8 bits; 119 here, the final unit of encoded output will be two 120 characters followed by two "=" padding characters, or 121 (3) the final quantum of encoding input is exactly 16 bits; 122 here, the final unit of encoded output will be three 123 characters followed by one "=" padding character. 124 */ 125 126 int 127 local_b64_ntop(uint8_t const *src, size_t srclength, char *target, size_t targsize) { 128 size_t datalength = 0; 129 uint8_t input[3]; 130 uint8_t output[4]; 131 size_t i; 132 133 while (2 < srclength) { 134 input[0] = *src++; 135 input[1] = *src++; 136 input[2] = *src++; 137 srclength -= 3; 138 139 output[0] = input[0] >> 2; 140 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); 141 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); 142 output[3] = input[2] & 0x3f; 143 Assert(output[0] < 64); 144 Assert(output[1] < 64); 145 Assert(output[2] < 64); 146 Assert(output[3] < 64); 147 148 if (datalength + 4 > targsize) 149 return (-1); 150 target[datalength++] = Base64[output[0]]; 151 target[datalength++] = Base64[output[1]]; 152 target[datalength++] = Base64[output[2]]; 153 target[datalength++] = Base64[output[3]]; 154 } 155 156 /* Now we worry about padding. */ 157 if (0 != srclength) { 158 /* Get what's left. */ 159 input[0] = input[1] = input[2] = '\0'; 160 for (i = 0; i < srclength; i++) 161 input[i] = *src++; 162 output[0] = input[0] >> 2; 163 output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4); 164 output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6); 165 Assert(output[0] < 64); 166 Assert(output[1] < 64); 167 Assert(output[2] < 64); 168 169 if (datalength + 4 > targsize) 170 return (-1); 171 target[datalength++] = Base64[output[0]]; 172 target[datalength++] = Base64[output[1]]; 173 if (srclength == 1) 174 target[datalength++] = Pad64; 175 else 176 target[datalength++] = Base64[output[2]]; 177 target[datalength++] = Pad64; 178 } 179 if (datalength >= targsize) 180 return (-1); 181 target[datalength] = '\0'; /* Returned value doesn't count \0. */ 182 return (datalength); 183 }