xref: /freebsd/crypto/heimdal/lib/roken/base64.c (revision 7aa383846770374466b1dcb2cefd71bde9acf463)
1 /*
2  * Copyright (c) 1995-2001 Kungliga Tekniska H�gskolan
3  * (Royal Institute of Technology, Stockholm, Sweden).
4  * All rights reserved.
5  *
6  * Redistribution and use in source and binary forms, with or without
7  * modification, are permitted provided that the following conditions
8  * are met:
9  *
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  *
13  * 2. Redistributions in binary form must reproduce the above copyright
14  *    notice, this list of conditions and the following disclaimer in the
15  *    documentation and/or other materials provided with the distribution.
16  *
17  * 3. Neither the name of the Institute nor the names of its contributors
18  *    may be used to endorse or promote products derived from this software
19  *    without specific prior written permission.
20  *
21  * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  */
33 
34 #ifdef HAVE_CONFIG_H
35 #include <config.h>
36 RCSID("$Id: base64.c 15506 2005-06-23 10:47:57Z lha $");
37 #endif
38 #include <stdlib.h>
39 #include <string.h>
40 #include "base64.h"
41 
42 static const char base64_chars[] =
43     "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
44 
45 static int
46 pos(char c)
47 {
48     const char *p;
49     for (p = base64_chars; *p; p++)
50 	if (*p == c)
51 	    return p - base64_chars;
52     return -1;
53 }
54 
55 int ROKEN_LIB_FUNCTION
56 base64_encode(const void *data, int size, char **str)
57 {
58     char *s, *p;
59     int i;
60     int c;
61     const unsigned char *q;
62 
63     p = s = (char *) malloc(size * 4 / 3 + 4);
64     if (p == NULL)
65 	return -1;
66     q = (const unsigned char *) data;
67     i = 0;
68     for (i = 0; i < size;) {
69 	c = q[i++];
70 	c *= 256;
71 	if (i < size)
72 	    c += q[i];
73 	i++;
74 	c *= 256;
75 	if (i < size)
76 	    c += q[i];
77 	i++;
78 	p[0] = base64_chars[(c & 0x00fc0000) >> 18];
79 	p[1] = base64_chars[(c & 0x0003f000) >> 12];
80 	p[2] = base64_chars[(c & 0x00000fc0) >> 6];
81 	p[3] = base64_chars[(c & 0x0000003f) >> 0];
82 	if (i > size)
83 	    p[3] = '=';
84 	if (i > size + 1)
85 	    p[2] = '=';
86 	p += 4;
87     }
88     *p = 0;
89     *str = s;
90     return strlen(s);
91 }
92 
93 #define DECODE_ERROR 0xffffffff
94 
95 static unsigned int
96 token_decode(const char *token)
97 {
98     int i;
99     unsigned int val = 0;
100     int marker = 0;
101     if (strlen(token) < 4)
102 	return DECODE_ERROR;
103     for (i = 0; i < 4; i++) {
104 	val *= 64;
105 	if (token[i] == '=')
106 	    marker++;
107 	else if (marker > 0)
108 	    return DECODE_ERROR;
109 	else
110 	    val += pos(token[i]);
111     }
112     if (marker > 2)
113 	return DECODE_ERROR;
114     return (marker << 24) | val;
115 }
116 
117 int ROKEN_LIB_FUNCTION
118 base64_decode(const char *str, void *data)
119 {
120     const char *p;
121     unsigned char *q;
122 
123     q = data;
124     for (p = str; *p && (*p == '=' || strchr(base64_chars, *p)); p += 4) {
125 	unsigned int val = token_decode(p);
126 	unsigned int marker = (val >> 24) & 0xff;
127 	if (val == DECODE_ERROR)
128 	    return -1;
129 	*q++ = (val >> 16) & 0xff;
130 	if (marker < 2)
131 	    *q++ = (val >> 8) & 0xff;
132 	if (marker < 1)
133 	    *q++ = val & 0xff;
134     }
135     return q - (unsigned char *) data;
136 }
137