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Diffstat (limited to 'src/base64.c')
| -rw-r--r-- | src/base64.c | 206 |
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diff --git a/src/base64.c b/src/base64.c new file mode 100644 index 0000000..496f697 --- /dev/null +++ b/src/base64.c @@ -0,0 +1,206 @@ +/* + * Copyright (c) 1995 - 1999 Kungliga Tekniska Högskolan + * (Royal Institute of Technology, Stockholm, Sweden). + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * 3. Neither the name of the Institute nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +/* (From RFC1521 and draft-ietf-dnssec-secext-03.txt) + The following encoding technique is taken from RFC 1521 by Borenstein + and Freed. It is reproduced here in a slightly edited form for + convenience. + + A 65-character subset of US-ASCII is used, enabling 6 bits to be + represented per printable character. (The extra 65th character, "=", + is used to signify a special processing function.) + + The encoding process represents 24-bit groups of input bits as output + strings of 4 encoded characters. Proceeding from left to right, a + 24-bit input group is formed by concatenating 3 8-bit input groups. + These 24 bits are then treated as 4 concatenated 6-bit groups, each + of which is translated into a single digit in the base64 alphabet. + + Each 6-bit group is used as an index into an array of 64 printable + characters. The character referenced by the index is placed in the + output string. + + Table 1: The Base64 Alphabet + + Value Encoding Value Encoding Value Encoding Value Encoding + 0 A 17 R 34 i 51 z + 1 B 18 S 35 j 52 0 + 2 C 19 T 36 k 53 1 + 3 D 20 U 37 l 54 2 + 4 E 21 V 38 m 55 3 + 5 F 22 W 39 n 56 4 + 6 G 23 X 40 o 57 5 + 7 H 24 Y 41 p 58 6 + 8 I 25 Z 42 q 59 7 + 9 J 26 a 43 r 60 8 + 10 K 27 b 44 s 61 9 + 11 L 28 c 45 t 62 + + 12 M 29 d 46 u 63 / + 13 N 30 e 47 v + 14 O 31 f 48 w (pad) = + 15 P 32 g 49 x + 16 Q 33 h 50 y + + Special processing is performed if fewer than 24 bits are available + at the end of the data being encoded. A full encoding quantum is + always completed at the end of a quantity. When fewer than 24 input + bits are available in an input group, zero bits are added (on the + right) to form an integral number of 6-bit groups. Padding at the + end of the data is performed using the '=' character. + + Since all base64 input is an integral number of octets, only the + ------------------------------------------------- + following cases can arise: + + (1) the final quantum of encoding input is an integral + multiple of 24 bits; here, the final unit of encoded + output will be an integral multiple of 4 characters + with no "=" padding, + (2) the final quantum of encoding input is exactly 8 bits; + here, the final unit of encoded output will be two + characters followed by two "=" padding characters, or + (3) the final quantum of encoding input is exactly 16 bits; + here, the final unit of encoded output will be three + characters followed by one "=" padding character. + */ + +/* $Id: base64.c,v 1.5 2001/05/28 17:33:41 joda Exp $ */ + +/* + * Code taken from Kerberos krb4-1.2.2 + */ + +#include <stdlib.h> +#include <string.h> +#include "base64.h" + +static char base64_chars[] = + "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; + +static int +pos(char c) +{ + char *p; + for (p = base64_chars; *p; p++) + if (*p == c) + return p - base64_chars; + return -1; +} + +int +base64_encode(const void *data, int size, char **str) +{ + char *s, *p; + int i; + int c; + const unsigned char *q; + + p = s = (char *) malloc(size * 4 / 3 + 4); + if (p == NULL) + return -1; + q = (const unsigned char *) data; + i = 0; + for (i = 0; i < size;) + { + c = q[i++]; + c *= 256; + if (i < size) + c += q[i]; + i++; + c *= 256; + if (i < size) + c += q[i]; + i++; + p[0] = base64_chars[(c & 0x00fc0000) >> 18]; + p[1] = base64_chars[(c & 0x0003f000) >> 12]; + p[2] = base64_chars[(c & 0x00000fc0) >> 6]; + p[3] = base64_chars[(c & 0x0000003f) >> 0]; + if (i > size) + p[3] = '='; + if (i > size + 1) + p[2] = '='; + p += 4; + } + *p = 0; + *str = s; + return strlen(s); +} + +#define DECODE_ERROR 0xffffffff + +static unsigned int +token_decode(const char *token) +{ + int i; + unsigned int val = 0; + int marker = 0; + + if (strlen(token) < 4) + return DECODE_ERROR; + for (i = 0; i < 4; i++) + { + val *= 64; + if (token[i] == '=') + marker++; + else if (marker > 0) + return DECODE_ERROR; + else + val += pos(token[i]); + } + if (marker > 2) + return DECODE_ERROR; + return (marker << 24) | val; +} + +int +base64_decode(const char *str, void *data) +{ + const char *p; + unsigned char *q; + + q = data; + for (p = str; *p && (*p == '=' || strchr(base64_chars, *p)); p += 4) + { + unsigned int val = token_decode(p); + unsigned int marker = (val >> 24) & 0xff; + + if (val == DECODE_ERROR) + return -1; + *q++ = (val >> 16) & 0xff; + if (marker < 2) + *q++ = (val >> 8) & 0xff; + if (marker < 1) + *q++ = val & 0xff; + } + return q - (unsigned char *) data; +} |