1/*
2 * Base64 encoding/decoding (RFC1341)
3 * Copyright (c) 2005-2019, 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#include <stdint.h>
11
12#include "os.h"
13#include "base64.h"
14
15static const unsigned char base64_table[65] =
16	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
17static const unsigned char base64_url_table[65] =
18	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
19
20
21static unsigned char * base64_gen_encode(const unsigned char *src, size_t len,
22					 size_t *out_len,
23					 const unsigned char *table,
24					 int add_pad)
25{
26	unsigned char *out, *pos;
27	const unsigned char *end, *in;
28	size_t olen;
29	int line_len;
30
31	if (len >= SIZE_MAX / 4)
32		return NULL;
33	olen = len * 4 / 3 + 4; /* 3-byte blocks to 4-byte */
34	if (add_pad)
35		olen += olen / 72; /* line feeds */
36	olen++; /* nul termination */
37	if (olen < len)
38		return NULL; /* integer overflow */
39	out = os_malloc(olen);
40	if (out == NULL)
41		return NULL;
42
43	end = src + len;
44	in = src;
45	pos = out;
46	line_len = 0;
47	while (end - in >= 3) {
48		*pos++ = table[(in[0] >> 2) & 0x3f];
49		*pos++ = table[(((in[0] & 0x03) << 4) | (in[1] >> 4)) & 0x3f];
50		*pos++ = table[(((in[1] & 0x0f) << 2) | (in[2] >> 6)) & 0x3f];
51		*pos++ = table[in[2] & 0x3f];
52		in += 3;
53		line_len += 4;
54		if (add_pad && line_len >= 72) {
55			*pos++ = '\n';
56			line_len = 0;
57		}
58	}
59
60	if (end - in) {
61		*pos++ = table[(in[0] >> 2) & 0x3f];
62		if (end - in == 1) {
63			*pos++ = table[((in[0] & 0x03) << 4) & 0x3f];
64			if (add_pad)
65				*pos++ = '=';
66		} else {
67			*pos++ = table[(((in[0] & 0x03) << 4) |
68					(in[1] >> 4)) & 0x3f];
69			*pos++ = table[((in[1] & 0x0f) << 2) & 0x3f];
70		}
71		if (add_pad)
72			*pos++ = '=';
73		line_len += 4;
74	}
75
76	if (add_pad && line_len)
77		*pos++ = '\n';
78
79	*pos = '\0';
80	if (out_len)
81		*out_len = pos - out;
82	return out;
83}
84
85
86static unsigned char * base64_gen_decode(const unsigned char *src, size_t len,
87					 size_t *out_len,
88					 const unsigned char *table)
89{
90	unsigned char dtable[256], *out, *pos, block[4], tmp;
91	size_t i, count, olen;
92	int pad = 0;
93	size_t extra_pad;
94
95	os_memset(dtable, 0x80, 256);
96	for (i = 0; i < sizeof(base64_table) - 1; i++)
97		dtable[table[i]] = (unsigned char) i;
98	dtable['='] = 0;
99
100	count = 0;
101	for (i = 0; i < len; i++) {
102		if (dtable[src[i]] != 0x80)
103			count++;
104	}
105
106	if (count == 0)
107		return NULL;
108	extra_pad = (4 - count % 4) % 4;
109
110	olen = (count + extra_pad) / 4 * 3;
111	pos = out = os_malloc(olen);
112	if (out == NULL)
113		return NULL;
114
115	count = 0;
116	for (i = 0; i < len + extra_pad; i++) {
117		unsigned char val;
118
119		if (i >= len)
120			val = '=';
121		else
122			val = src[i];
123		tmp = dtable[val];
124		if (tmp == 0x80)
125			continue;
126
127		if (val == '=')
128			pad++;
129		block[count] = tmp;
130		count++;
131		if (count == 4) {
132			*pos++ = (block[0] << 2) | (block[1] >> 4);
133			*pos++ = (block[1] << 4) | (block[2] >> 2);
134			*pos++ = (block[2] << 6) | block[3];
135			count = 0;
136			if (pad) {
137				if (pad == 1)
138					pos--;
139				else if (pad == 2)
140					pos -= 2;
141				else {
142					/* Invalid padding */
143					os_free(out);
144					return NULL;
145				}
146				break;
147			}
148		}
149	}
150
151	*out_len = pos - out;
152	return out;
153}
154
155
156/**
157 * base64_encode - Base64 encode
158 * @src: Data to be encoded
159 * @len: Length of the data to be encoded
160 * @out_len: Pointer to output length variable, or %NULL if not used
161 * Returns: Allocated buffer of out_len bytes of encoded data,
162 * or %NULL on failure
163 *
164 * Caller is responsible for freeing the returned buffer. Returned buffer is
165 * nul terminated to make it easier to use as a C string. The nul terminator is
166 * not included in out_len.
167 */
168unsigned char * base64_encode(const unsigned char *src, size_t len,
169			      size_t *out_len)
170{
171	return base64_gen_encode(src, len, out_len, base64_table, 1);
172}
173
174
175unsigned char * base64_url_encode(const unsigned char *src, size_t len,
176				  size_t *out_len, int add_pad)
177{
178	return base64_gen_encode(src, len, out_len, base64_url_table, add_pad);
179}
180
181
182/**
183 * base64_decode - Base64 decode
184 * @src: Data to be decoded
185 * @len: Length of the data to be decoded
186 * @out_len: Pointer to output length variable
187 * Returns: Allocated buffer of out_len bytes of decoded data,
188 * or %NULL on failure
189 *
190 * Caller is responsible for freeing the returned buffer.
191 */
192unsigned char * base64_decode(const unsigned char *src, size_t len,
193			      size_t *out_len)
194{
195	return base64_gen_decode(src, len, out_len, base64_table);
196}
197
198
199unsigned char * base64_url_decode(const unsigned char *src, size_t len,
200				  size_t *out_len)
201{
202	return base64_gen_decode(src, len, out_len, base64_url_table);
203}
204