base64.c revision c5ec7f57ead87efa365800228aa0b09a12d9e6c4 
1/*
2 * Base64 encoding/decoding (RFC1341)
3 * Copyright (c) 2005-2011, Jouni Malinen <j@w1.fi>
4 *
5 * This software may be distributed under the terms of the BSD license.
6 * See README for more details.
7 */
8
9#include "includes.h"
10
11#include "os.h"
12#include "base64.h"
13
14static const unsigned char base64_table[65] =
15	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
16
17/**
18 * base64_encode - Base64 encode
19 * @src: Data to be encoded
20 * @len: Length of the data to be encoded
21 * @out_len: Pointer to output length variable, or %NULL if not used
22 * Returns: Allocated buffer of out_len bytes of encoded data,
23 * or %NULL on failure
24 *
25 * Caller is responsible for freeing the returned buffer. Returned buffer is
26 * nul terminated to make it easier to use as a C string. The nul terminator is
27 * not included in out_len.
28 */
29unsigned char * base64_encode(const unsigned char *src, size_t len,
30			      size_t *out_len)
31{
32	unsigned char *out, *pos;
33	const unsigned char *end, *in;
34	size_t olen;
35	int line_len;
36
37	olen = len * 4 / 3 + 4; /* 3-byte blocks to 4-byte */
38	olen += olen / 72; /* line feeds */
39	olen++; /* nul termination */
40	if (olen < len)
41		return NULL; /* integer overflow */
42	out = os_malloc(olen);
43	if (out == NULL)
44		return NULL;
45
46	end = src + len;
47	in = src;
48	pos = out;
49	line_len = 0;
50	while (end - in >= 3) {
51		*pos++ = base64_table[in[0] >> 2];
52		*pos++ = base64_table[((in[0] & 0x03) << 4) | (in[1] >> 4)];
53		*pos++ = base64_table[((in[1] & 0x0f) << 2) | (in[2] >> 6)];
54		*pos++ = base64_table[in[2] & 0x3f];
55		in += 3;
56		line_len += 4;
57		if (line_len >= 72) {
58			*pos++ = '\n';
59			line_len = 0;
60		}
61	}
62
63	if (end - in) {
64		*pos++ = base64_table[in[0] >> 2];
65		if (end - in == 1) {
66			*pos++ = base64_table[(in[0] & 0x03) << 4];
67			*pos++ = '=';
68		} else {
69			*pos++ = base64_table[((in[0] & 0x03) << 4) |
70					      (in[1] >> 4)];
71			*pos++ = base64_table[(in[1] & 0x0f) << 2];
72		}
73		*pos++ = '=';
74		line_len += 4;
75	}
76
77	if (line_len)
78		*pos++ = '\n';
79
80	*pos = '\0';
81	if (out_len)
82		*out_len = pos - out;
83	return out;
84}
85
86
87/**
88 * base64_decode - Base64 decode
89 * @src: Data to be decoded
90 * @len: Length of the data to be decoded
91 * @out_len: Pointer to output length variable
92 * Returns: Allocated buffer of out_len bytes of decoded data,
93 * or %NULL on failure
94 *
95 * Caller is responsible for freeing the returned buffer.
96 */
97unsigned char * base64_decode(const unsigned char *src, size_t len,
98			      size_t *out_len)
99{
100	unsigned char dtable[256], *out, *pos, block[4], tmp;
101	size_t i, count, olen;
102	int pad = 0;
103
104	os_memset(dtable, 0x80, 256);
105	for (i = 0; i < sizeof(base64_table) - 1; i++)
106		dtable[base64_table[i]] = (unsigned char) i;
107	dtable['='] = 0;
108
109	count = 0;
110	for (i = 0; i < len; i++) {
111		if (dtable[src[i]] != 0x80)
112			count++;
113	}
114
115	if (count == 0 || count % 4)
116		return NULL;
117
118	olen = count / 4 * 3;
119	pos = out = os_malloc(olen);
120	if (out == NULL)
121		return NULL;
122
123	count = 0;
124	for (i = 0; i < len; i++) {
125		tmp = dtable[src[i]];
126		if (tmp == 0x80)
127			continue;
128
129		if (src[i] == '=')
130			pad++;
131		block[count] = tmp;
132		count++;
133		if (count == 4) {
134			*pos++ = (block[0] << 2) | (block[1] >> 4);
135			*pos++ = (block[1] << 4) | (block[2] >> 2);
136			*pos++ = (block[2] << 6) | block[3];
137			count = 0;
138			if (pad) {
139				if (pad == 1)
140					pos--;
141				else if (pad == 2)
142					pos -= 2;
143				else {
144					/* Invalid padding */
145					os_free(out);
146					return NULL;
147				}
148				break;
149			}
150		}
151	}
152
153	*out_len = pos - out;
154	return out;
155}
156