1/*
2 * Copyright (c) 1996, 1998 by Internet Software Consortium.
3 *
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
9 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
10 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
11 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
12 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
13 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
14 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
15 * SOFTWARE.
16 */
17
18/*
19 * Portions Copyright (c) 1995 by International Business Machines, Inc.
20 *
21 * International Business Machines, Inc. (hereinafter called IBM) grants
22 * permission under its copyrights to use, copy, modify, and distribute this
23 * Software with or without fee, provided that the above copyright notice and
24 * all paragraphs of this notice appear in all copies, and that the name of IBM
25 * not be used in connection with the marketing of any product incorporating
26 * the Software or modifications thereof, without specific, written prior
27 * permission.
28 *
29 * To the extent it has a right to do so, IBM grants an immunity from suit
30 * under its patents, if any, for the use, sale or manufacture of products to
31 * the extent that such products are used for performing Domain Name System
32 * dynamic updates in TCP/IP networks by means of the Software.  No immunity is
33 * granted for any product per se or for any other function of any product.
34 *
35 * THE SOFTWARE IS PROVIDED "AS IS", AND IBM DISCLAIMS ALL WARRANTIES,
36 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
37 * PARTICULAR PURPOSE.  IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL,
38 * DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER ARISING
39 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE, EVEN
40 * IF IBM IS APPRISED OF THE POSSIBILITY OF SUCH DAMAGES.
41 */
42
43#include <sys/cdefs.h>
44__FBSDID("$FreeBSD: releng/10.3/lib/libc/net/base64.c 280399 2015-03-23 20:51:35Z emaste $");
45
46#include <sys/types.h>
47#include <sys/param.h>
48#include <sys/socket.h>
49
50#include <netinet/in.h>
51#include <arpa/inet.h>
52#include <arpa/nameser.h>
53
54#include <ctype.h>
55#include <resolv.h>
56#include <stdio.h>
57#include <stdlib.h>
58#include <string.h>
59
60#define Assert(Cond) if (!(Cond)) abort()
61
62static const char Base64[] =
63	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
64static const char Pad64 = '=';
65
66/* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
67   The following encoding technique is taken from RFC 1521 by Borenstein
68   and Freed.  It is reproduced here in a slightly edited form for
69   convenience.
70
71   A 65-character subset of US-ASCII is used, enabling 6 bits to be
72   represented per printable character. (The extra 65th character, "=",
73   is used to signify a special processing function.)
74
75   The encoding process represents 24-bit groups of input bits as output
76   strings of 4 encoded characters. Proceeding from left to right, a
77   24-bit input group is formed by concatenating 3 8-bit input groups.
78   These 24 bits are then treated as 4 concatenated 6-bit groups, each
79   of which is translated into a single digit in the base64 alphabet.
80
81   Each 6-bit group is used as an index into an array of 64 printable
82   characters. The character referenced by the index is placed in the
83   output string.
84
85                         Table 1: The Base64 Alphabet
86
87      Value Encoding  Value Encoding  Value Encoding  Value Encoding
88          0 A            17 R            34 i            51 z
89          1 B            18 S            35 j            52 0
90          2 C            19 T            36 k            53 1
91          3 D            20 U            37 l            54 2
92          4 E            21 V            38 m            55 3
93          5 F            22 W            39 n            56 4
94          6 G            23 X            40 o            57 5
95          7 H            24 Y            41 p            58 6
96          8 I            25 Z            42 q            59 7
97          9 J            26 a            43 r            60 8
98         10 K            27 b            44 s            61 9
99         11 L            28 c            45 t            62 +
100         12 M            29 d            46 u            63 /
101         13 N            30 e            47 v
102         14 O            31 f            48 w         (pad) =
103         15 P            32 g            49 x
104         16 Q            33 h            50 y
105
106   Special processing is performed if fewer than 24 bits are available
107   at the end of the data being encoded.  A full encoding quantum is
108   always completed at the end of a quantity.  When fewer than 24 input
109   bits are available in an input group, zero bits are added (on the
110   right) to form an integral number of 6-bit groups.  Padding at the
111   end of the data is performed using the '=' character.
112
113   Since all base64 input is an integral number of octets, only the
114         -------------------------------------------------
115   following cases can arise:
116
117       (1) the final quantum of encoding input is an integral
118           multiple of 24 bits; here, the final unit of encoded
119	   output will be an integral multiple of 4 characters
120	   with no "=" padding,
121       (2) the final quantum of encoding input is exactly 8 bits;
122           here, the final unit of encoded output will be two
123	   characters followed by two "=" padding characters, or
124       (3) the final quantum of encoding input is exactly 16 bits;
125           here, the final unit of encoded output will be three
126	   characters followed by one "=" padding character.
127   */
128
129int
130b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize) {
131	size_t datalength = 0;
132	u_char input[3];
133	u_char output[4];
134	size_t i;
135
136	while (2 < srclength) {
137		input[0] = *src++;
138		input[1] = *src++;
139		input[2] = *src++;
140		srclength -= 3;
141
142		output[0] = input[0] >> 2;
143		output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
144		output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
145		output[3] = input[2] & 0x3f;
146		Assert(output[0] < 64);
147		Assert(output[1] < 64);
148		Assert(output[2] < 64);
149		Assert(output[3] < 64);
150
151		if (datalength + 4 > targsize)
152			return (-1);
153		target[datalength++] = Base64[output[0]];
154		target[datalength++] = Base64[output[1]];
155		target[datalength++] = Base64[output[2]];
156		target[datalength++] = Base64[output[3]];
157	}
158
159	/* Now we worry about padding. */
160	if (0 != srclength) {
161		/* Get what's left. */
162		input[0] = input[1] = input[2] = '\0';
163		for (i = 0; i < srclength; i++)
164			input[i] = *src++;
165
166		output[0] = input[0] >> 2;
167		output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
168		output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
169		Assert(output[0] < 64);
170		Assert(output[1] < 64);
171		Assert(output[2] < 64);
172
173		if (datalength + 4 > targsize)
174			return (-1);
175		target[datalength++] = Base64[output[0]];
176		target[datalength++] = Base64[output[1]];
177		if (srclength == 1)
178			target[datalength++] = Pad64;
179		else
180			target[datalength++] = Base64[output[2]];
181		target[datalength++] = Pad64;
182	}
183	if (datalength >= targsize)
184		return (-1);
185	target[datalength] = '\0';	/* Returned value doesn't count \0. */
186	return (datalength);
187}
188
189/* skips all whitespace anywhere.
190   converts characters, four at a time, starting at (or after)
191   src from base - 64 numbers into three 8 bit bytes in the target area.
192   it returns the number of data bytes stored at the target, or -1 on error.
193 */
194
195int
196b64_pton(const char *src, u_char *target, size_t targsize)
197{
198	int tarindex, state, ch;
199	u_char nextbyte;
200	char *pos;
201
202	state = 0;
203	tarindex = 0;
204
205	while ((ch = *src++) != '\0') {
206		if (isspace((unsigned char)ch))        /* Skip whitespace anywhere. */
207			continue;
208
209		if (ch == Pad64)
210			break;
211
212		pos = strchr(Base64, ch);
213		if (pos == 0) 		/* A non-base64 character. */
214			return (-1);
215
216		switch (state) {
217		case 0:
218			if (target) {
219				if ((size_t)tarindex >= targsize)
220					return (-1);
221				target[tarindex] = (pos - Base64) << 2;
222			}
223			state = 1;
224			break;
225		case 1:
226			if (target) {
227				if ((size_t)tarindex >= targsize)
228					return (-1);
229				target[tarindex]   |=  (pos - Base64) >> 4;
230				nextbyte = ((pos - Base64) & 0x0f) << 4;
231				if ((size_t)tarindex + 1 < targsize)
232					target[tarindex + 1] = nextbyte;
233				else if (nextbyte)
234					return (-1);
235			}
236			tarindex++;
237			state = 2;
238			break;
239		case 2:
240			if (target) {
241				if ((size_t)tarindex >= targsize)
242					return (-1);
243				target[tarindex]   |=  (pos - Base64) >> 2;
244				nextbyte = ((pos - Base64) & 0x03) << 6;
245				if ((size_t)tarindex + 1 < targsize)
246					target[tarindex + 1] = nextbyte;
247				else if (nextbyte)
248					return (-1);
249			}
250			tarindex++;
251			state = 3;
252			break;
253		case 3:
254			if (target) {
255				if ((size_t)tarindex >= targsize)
256					return (-1);
257				target[tarindex] |= (pos - Base64);
258			}
259			tarindex++;
260			state = 0;
261			break;
262		default:
263			abort();
264		}
265	}
266
267	/*
268	 * We are done decoding Base-64 chars.  Let's see if we ended
269	 * on a byte boundary, and/or with erroneous trailing characters.
270	 */
271
272	if (ch == Pad64) {		/* We got a pad char. */
273		ch = *src++;		/* Skip it, get next. */
274		switch (state) {
275		case 0:		/* Invalid = in first position */
276		case 1:		/* Invalid = in second position */
277			return (-1);
278
279		case 2:		/* Valid, means one byte of info */
280			/* Skip any number of spaces. */
281			for ((void)NULL; ch != '\0'; ch = *src++)
282				if (!isspace((unsigned char)ch))
283					break;
284			/* Make sure there is another trailing = sign. */
285			if (ch != Pad64)
286				return (-1);
287			ch = *src++;		/* Skip the = */
288			/* Fall through to "single trailing =" case. */
289			/* FALLTHROUGH */
290
291		case 3:		/* Valid, means two bytes of info */
292			/*
293			 * We know this char is an =.  Is there anything but
294			 * whitespace after it?
295			 */
296			for ((void)NULL; ch != '\0'; ch = *src++)
297				if (!isspace((unsigned char)ch))
298					return (-1);
299
300			/*
301			 * Now make sure for cases 2 and 3 that the "extra"
302			 * bits that slopped past the last full byte were
303			 * zeros.  If we don't check them, they become a
304			 * subliminal channel.
305			 */
306			if (target && (size_t)tarindex < targsize &&
307			    target[tarindex] != 0)
308				return (-1);
309		}
310	} else {
311		/*
312		 * We ended by seeing the end of the string.  Make sure we
313		 * have no partial bytes lying around.
314		 */
315		if (state != 0)
316			return (-1);
317	}
318
319	return (tarindex);
320}
321