186 lines
7.2 KiB
C
186 lines
7.2 KiB
C
/*
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* Copyright (c) 1996, 1998 by Internet Software Consortium.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
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* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
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* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
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* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
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* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
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* SOFTWARE.
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*/
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/*
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* Portions Copyright (c) 1995 by International Business Machines, Inc.
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*
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* International Business Machines, Inc. (hereinafter called IBM) grants
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* permission under its copyrights to use, copy, modify, and distribute this
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* Software with or without fee, provided that the above copyright notice and
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* all paragraphs of this notice appear in all copies, and that the name of IBM
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* not be used in connection with the marketing of any product incorporating
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* the Software or modifications thereof, without specific, written prior
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* permission.
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*
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* To the extent it has a right to do so, IBM grants an immunity from suit
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* under its patents, if any, for the use, sale or manufacture of products to
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* the extent that such products are used for performing Domain Name System
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* dynamic updates in TCP/IP networks by means of the Software. No immunity is
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* granted for any product per se or for any other function of any product.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", AND IBM DISCLAIMS ALL WARRANTIES,
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* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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* PARTICULAR PURPOSE. IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL,
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* DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER ARISING
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* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE, EVEN
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* IF IBM IS APPRISED OF THE POSSIBILITY OF SUCH DAMAGES.
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*/
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#include <ldns/config.h>
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#include <ctype.h>
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#include <stdlib.h>
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#include <string.h>
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static const char Base64[] =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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static const char Pad64 = '=';
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/* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
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The following encoding technique is taken from RFC 1521 by Borenstein
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and Freed. It is reproduced here in a slightly edited form for
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convenience.
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A 65-character subset of US-ASCII is used, enabling 6 bits to be
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represented per printable character. (The extra 65th character, "=",
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is used to signify a special processing function.)
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The encoding process represents 24-bit groups of input bits as output
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strings of 4 encoded characters. Proceeding from left to right, a
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24-bit input group is formed by concatenating 3 8-bit input groups.
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These 24 bits are then treated as 4 concatenated 6-bit groups, each
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of which is translated into a single digit in the base64 alphabet.
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Each 6-bit group is used as an index into an array of 64 printable
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characters. The character referenced by the index is placed in the
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output string.
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Table 1: The Base64 Alphabet
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Value Encoding Value Encoding Value Encoding Value Encoding
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0 A 17 R 34 i 51 z
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1 B 18 S 35 j 52 0
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2 C 19 T 36 k 53 1
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3 D 20 U 37 l 54 2
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4 E 21 V 38 m 55 3
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5 F 22 W 39 n 56 4
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6 G 23 X 40 o 57 5
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7 H 24 Y 41 p 58 6
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8 I 25 Z 42 q 59 7
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9 J 26 a 43 r 60 8
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10 K 27 b 44 s 61 9
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11 L 28 c 45 t 62 +
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12 M 29 d 46 u 63 /
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13 N 30 e 47 v
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14 O 31 f 48 w (pad) =
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15 P 32 g 49 x
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16 Q 33 h 50 y
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Special processing is performed if fewer than 24 bits are available
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at the end of the data being encoded. A full encoding quantum is
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always completed at the end of a quantity. When fewer than 24 input
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bits are available in an input group, zero bits are added (on the
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right) to form an integral number of 6-bit groups. Padding at the
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end of the data is performed using the '=' character.
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Since all base64 input is an integral number of octets, only the
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-------------------------------------------------
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following cases can arise:
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(1) the final quantum of encoding input is an integral
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multiple of 24 bits; here, the final unit of encoded
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output will be an integral multiple of 4 characters
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with no "=" padding,
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(2) the final quantum of encoding input is exactly 8 bits;
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here, the final unit of encoded output will be two
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characters followed by two "=" padding characters, or
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(3) the final quantum of encoding input is exactly 16 bits;
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here, the final unit of encoded output will be three
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characters followed by one "=" padding character.
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*/
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int
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ldns_b64_ntop(uint8_t const *src, size_t srclength, char *target, size_t targsize) {
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size_t datalength = 0;
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uint8_t input[3];
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uint8_t output[4];
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size_t i;
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if (srclength == 0) {
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if (targsize > 0) {
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target[0] = '\0';
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return 0;
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} else {
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return -1;
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}
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}
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while (2 < srclength) {
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input[0] = *src++;
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input[1] = *src++;
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input[2] = *src++;
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srclength -= 3;
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output[0] = input[0] >> 2;
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output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
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output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
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output[3] = input[2] & 0x3f;
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assert(output[0] < 64);
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assert(output[1] < 64);
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assert(output[2] < 64);
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assert(output[3] < 64);
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if (datalength + 4 > targsize) {
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return (-1);
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}
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target[datalength++] = Base64[output[0]];
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target[datalength++] = Base64[output[1]];
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target[datalength++] = Base64[output[2]];
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target[datalength++] = Base64[output[3]];
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}
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/* Now we worry about padding. */
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if (0 != srclength) {
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/* Get what's left. */
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input[0] = input[1] = input[2] = (uint8_t) '\0';
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for (i = 0; i < srclength; i++)
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input[i] = *src++;
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output[0] = input[0] >> 2;
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output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
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output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
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assert(output[0] < 64);
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assert(output[1] < 64);
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assert(output[2] < 64);
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if (datalength + 4 > targsize) {
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return (-2);
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}
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target[datalength++] = Base64[output[0]];
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target[datalength++] = Base64[output[1]];
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if (srclength == 1) {
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target[datalength++] = Pad64;
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} else {
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target[datalength++] = Base64[output[2]];
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}
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target[datalength++] = Pad64;
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}
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if (datalength >= targsize) {
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return (-3);
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}
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target[datalength] = '\0'; /* Returned value doesn't count \0. */
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return (int) (datalength);
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}
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