base64.c revision 8d520ff1dc2da35cdca849e982051b86468016d8 
1/*
2 * Base64 encoding/decoding (RFC1341)
3 * Copyright (c) 2005, Jouni Malinen <j@w1.fi>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 *
9 * Alternatively, this software may be distributed under the terms of BSD
10 * license.
11 *
12 * See README and COPYING for more details.
13 */
14
15#include "includes.h"
16
17#include "os.h"
18#include "base64.h"
19
20static const unsigned char base64_table[65] =
21	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
22
23/**
24 * base64_encode - Base64 encode
25 * @src: Data to be encoded
26 * @len: Length of the data to be encoded
27 * @out_len: Pointer to output length variable, or %NULL if not used
28 * Returns: Allocated buffer of out_len bytes of encoded data,
29 * or %NULL on failure
30 *
31 * Caller is responsible for freeing the returned buffer. Returned buffer is
32 * nul terminated to make it easier to use as a C string. The nul terminator is
33 * not included in out_len.
34 */
35unsigned char * base64_encode(const unsigned char *src, size_t len,
36			      size_t *out_len)
37{
38	unsigned char *out, *pos;
39	const unsigned char *end, *in;
40	size_t olen;
41	int line_len;
42
43	olen = len * 4 / 3 + 4; /* 3-byte blocks to 4-byte */
44	olen += olen / 72; /* line feeds */
45	olen++; /* nul termination */
46	if (olen < len)
47		return NULL; /* integer overflow */
48	out = os_malloc(olen);
49	if (out == NULL)
50		return NULL;
51
52	end = src + len;
53	in = src;
54	pos = out;
55	line_len = 0;
56	while (end - in >= 3) {
57		*pos++ = base64_table[in[0] >> 2];
58		*pos++ = base64_table[((in[0] & 0x03) << 4) | (in[1] >> 4)];
59		*pos++ = base64_table[((in[1] & 0x0f) << 2) | (in[2] >> 6)];
60		*pos++ = base64_table[in[2] & 0x3f];
61		in += 3;
62		line_len += 4;
63		if (line_len >= 72) {
64			*pos++ = '\n';
65			line_len = 0;
66		}
67	}
68
69	if (end - in) {
70		*pos++ = base64_table[in[0] >> 2];
71		if (end - in == 1) {
72			*pos++ = base64_table[(in[0] & 0x03) << 4];
73			*pos++ = '=';
74		} else {
75			*pos++ = base64_table[((in[0] & 0x03) << 4) |
76					      (in[1] >> 4)];
77			*pos++ = base64_table[(in[1] & 0x0f) << 2];
78		}
79		*pos++ = '=';
80		line_len += 4;
81	}
82
83	if (line_len)
84		*pos++ = '\n';
85
86	*pos = '\0';
87	if (out_len)
88		*out_len = pos - out;
89	return out;
90}
91
92
93/**
94 * base64_decode - Base64 decode
95 * @src: Data to be decoded
96 * @len: Length of the data to be decoded
97 * @out_len: Pointer to output length variable
98 * Returns: Allocated buffer of out_len bytes of decoded data,
99 * or %NULL on failure
100 *
101 * Caller is responsible for freeing the returned buffer.
102 */
103unsigned char * base64_decode(const unsigned char *src, size_t len,
104			      size_t *out_len)
105{
106	unsigned char dtable[256], *out, *pos, in[4], block[4], tmp;
107	size_t i, count, olen;
108
109	os_memset(dtable, 0x80, 256);
110	for (i = 0; i < sizeof(base64_table) - 1; i++)
111		dtable[base64_table[i]] = (unsigned char) i;
112	dtable['='] = 0;
113
114	count = 0;
115	for (i = 0; i < len; i++) {
116		if (dtable[src[i]] != 0x80)
117			count++;
118	}
119
120	if (count == 0 || count % 4)
121		return NULL;
122
123	olen = count / 4 * 3;
124	pos = out = os_malloc(olen);
125	if (out == NULL)
126		return NULL;
127
128	count = 0;
129	for (i = 0; i < len; i++) {
130		tmp = dtable[src[i]];
131		if (tmp == 0x80)
132			continue;
133
134		in[count] = src[i];
135		block[count] = tmp;
136		count++;
137		if (count == 4) {
138			*pos++ = (block[0] << 2) | (block[1] >> 4);
139			*pos++ = (block[1] << 4) | (block[2] >> 2);
140			*pos++ = (block[2] << 6) | block[3];
141			count = 0;
142		}
143	}
144
145	if (pos > out) {
146		if (in[2] == '=')
147			pos -= 2;
148		else if (in[3] == '=')
149			pos--;
150	}
151
152	*out_len = pos - out;
153	return out;
154}
155