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) & 0x3f];
52		*pos++ = base64_table[(((in[0] & 0x03) << 4) |
53				       (in[1] >> 4)) & 0x3f];
54		*pos++ = base64_table[(((in[1] & 0x0f) << 2) |
55				       (in[2] >> 6)) & 0x3f];
56		*pos++ = base64_table[in[2] & 0x3f];
57		in += 3;
58		line_len += 4;
59		if (line_len >= 72) {
60			*pos++ = '\n';
61			line_len = 0;
62		}
63	}
64
65	if (end - in) {
66		*pos++ = base64_table[(in[0] >> 2) & 0x3f];
67		if (end - in == 1) {
68			*pos++ = base64_table[((in[0] & 0x03) << 4) & 0x3f];
69			*pos++ = '=';
70		} else {
71			*pos++ = base64_table[(((in[0] & 0x03) << 4) |
72					       (in[1] >> 4)) & 0x3f];
73			*pos++ = base64_table[((in[1] & 0x0f) << 2) & 0x3f];
74		}
75		*pos++ = '=';
76		line_len += 4;
77	}
78
79	if (line_len)
80		*pos++ = '\n';
81
82	*pos = '\0';
83	if (out_len)
84		*out_len = pos - out;
85	return out;
86}
87
88
89/**
90 * base64_decode - Base64 decode
91 * @src: Data to be decoded
92 * @len: Length of the data to be decoded
93 * @out_len: Pointer to output length variable
94 * Returns: Allocated buffer of out_len bytes of decoded data,
95 * or %NULL on failure
96 *
97 * Caller is responsible for freeing the returned buffer.
98 */
99unsigned char * base64_decode(const unsigned char *src, size_t len,
100			      size_t *out_len)
101{
102	unsigned char dtable[256], *out, *pos, block[4], tmp;
103	size_t i, count, olen;
104	int pad = 0;
105
106	os_memset(dtable, 0x80, 256);
107	for (i = 0; i < sizeof(base64_table) - 1; i++)
108		dtable[base64_table[i]] = (unsigned char) i;
109	dtable['='] = 0;
110
111	count = 0;
112	for (i = 0; i < len; i++) {
113		if (dtable[src[i]] != 0x80)
114			count++;
115	}
116
117	if (count == 0 || count % 4)
118		return NULL;
119
120	olen = count / 4 * 3;
121	pos = out = os_malloc(olen);
122	if (out == NULL)
123		return NULL;
124
125	count = 0;
126	for (i = 0; i < len; i++) {
127		tmp = dtable[src[i]];
128		if (tmp == 0x80)
129			continue;
130
131		if (src[i] == '=')
132			pad++;
133		block[count] = tmp;
134		count++;
135		if (count == 4) {
136			*pos++ = (block[0] << 2) | (block[1] >> 4);
137			*pos++ = (block[1] << 4) | (block[2] >> 2);
138			*pos++ = (block[2] << 6) | block[3];
139			count = 0;
140			if (pad) {
141				if (pad == 1)
142					pos--;
143				else if (pad == 2)
144					pos -= 2;
145				else {
146					/* Invalid padding */
147					os_free(out);
148					return NULL;
149				}
150				break;
151			}
152		}
153	}
154
155	*out_len = pos - out;
156	return out;
157}
158