1/*	$NetBSD: base64.c,v 1.14 2012/06/25 22:32:44 abs Exp $	*/
2
3/*
4 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
5 * Copyright (c) 1996-1999 by Internet Software Consortium.
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
17 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20/*
21 * Portions Copyright (c) 1995 by International Business Machines, Inc.
22 *
23 * International Business Machines, Inc. (hereinafter called IBM) grants
24 * permission under its copyrights to use, copy, modify, and distribute this
25 * Software with or without fee, provided that the above copyright notice and
26 * all paragraphs of this notice appear in all copies, and that the name of IBM
27 * not be used in connection with the marketing of any product incorporating
28 * the Software or modifications thereof, without specific, written prior
29 * permission.
30 *
31 * To the extent it has a right to do so, IBM grants an immunity from suit
32 * under its patents, if any, for the use, sale or manufacture of products to
33 * the extent that such products are used for performing Domain Name System
34 * dynamic updates in TCP/IP networks by means of the Software.  No immunity is
35 * granted for any product per se or for any other function of any product.
36 *
37 * THE SOFTWARE IS PROVIDED "AS IS", AND IBM DISCLAIMS ALL WARRANTIES,
38 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
39 * PARTICULAR PURPOSE.  IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL,
40 * DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER ARISING
41 * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE, EVEN
42 * IF IBM IS APPRISED OF THE POSSIBILITY OF SUCH DAMAGES.
43 */
44
45#include <sys/cdefs.h>
46#if defined(LIBC_SCCS) && !defined(lint)
47#if 0
48static const char rcsid[] = "Id: base64.c,v 1.4 2005/04/27 04:56:34 sra Exp";
49#else
50__RCSID("$NetBSD: base64.c,v 1.14 2012/06/25 22:32:44 abs Exp $");
51#endif
52#endif /* LIBC_SCCS and not lint */
53
54#include "port_before.h"
55
56#include <sys/types.h>
57#include <sys/param.h>
58#include <sys/socket.h>
59
60#include <netinet/in.h>
61#include <arpa/inet.h>
62#include <arpa/nameser.h>
63
64#include <assert.h>
65#include <ctype.h>
66#include <resolv.h>
67#include <stdio.h>
68#include <stdlib.h>
69#include <string.h>
70
71#include "port_after.h"
72
73#define Assert(Cond) if (!(Cond)) abort()
74
75static const char Base64[] =
76	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
77static const char Pad64 = '=';
78
79/* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
80   The following encoding technique is taken from RFC1521 by Borenstein
81   and Freed.  It is reproduced here in a slightly edited form for
82   convenience.
83
84   A 65-character subset of US-ASCII is used, enabling 6 bits to be
85   represented per printable character. (The extra 65th character, "=",
86   is used to signify a special processing function.)
87
88   The encoding process represents 24-bit groups of input bits as output
89   strings of 4 encoded characters. Proceeding from left to right, a
90   24-bit input group is formed by concatenating 3 8-bit input groups.
91   These 24 bits are then treated as 4 concatenated 6-bit groups, each
92   of which is translated into a single digit in the base64 alphabet.
93
94   Each 6-bit group is used as an index into an array of 64 printable
95   characters. The character referenced by the index is placed in the
96   output string.
97
98                         Table 1: The Base64 Alphabet
99
100      Value Encoding  Value Encoding  Value Encoding  Value Encoding
101          0 A            17 R            34 i            51 z
102          1 B            18 S            35 j            52 0
103          2 C            19 T            36 k            53 1
104          3 D            20 U            37 l            54 2
105          4 E            21 V            38 m            55 3
106          5 F            22 W            39 n            56 4
107          6 G            23 X            40 o            57 5
108          7 H            24 Y            41 p            58 6
109          8 I            25 Z            42 q            59 7
110          9 J            26 a            43 r            60 8
111         10 K            27 b            44 s            61 9
112         11 L            28 c            45 t            62 +
113         12 M            29 d            46 u            63 /
114         13 N            30 e            47 v
115         14 O            31 f            48 w         (pad) =
116         15 P            32 g            49 x
117         16 Q            33 h            50 y
118
119   Special processing is performed if fewer than 24 bits are available
120   at the end of the data being encoded.  A full encoding quantum is
121   always completed at the end of a quantity.  When fewer than 24 input
122   bits are available in an input group, zero bits are added (on the
123   right) to form an integral number of 6-bit groups.  Padding at the
124   end of the data is performed using the '=' character.
125
126   Since all base64 input is an integral number of octets, only the
127         -------------------------------------------------
128   following cases can arise:
129
130       (1) the final quantum of encoding input is an integral
131           multiple of 24 bits; here, the final unit of encoded
132	   output will be an integral multiple of 4 characters
133	   with no "=" padding,
134       (2) the final quantum of encoding input is exactly 8 bits;
135           here, the final unit of encoded output will be two
136	   characters followed by two "=" padding characters, or
137       (3) the final quantum of encoding input is exactly 16 bits;
138           here, the final unit of encoded output will be three
139	   characters followed by one "=" padding character.
140   */
141
142int
143b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize) {
144	size_t datalength = 0;
145	u_char input[3];
146	u_char output[4];
147	size_t i;
148
149	assert(src != NULL);
150	assert(target != NULL);
151
152	while (2U < srclength) {
153		input[0] = *src++;
154		input[1] = *src++;
155		input[2] = *src++;
156		srclength -= 3;
157
158		output[0] = (u_int32_t)input[0] >> 2;
159		output[1] = ((u_int32_t)(input[0] & 0x03) << 4) +
160		    ((u_int32_t)input[1] >> 4);
161		output[2] = ((u_int32_t)(input[1] & 0x0f) << 2) +
162		    ((u_int32_t)input[2] >> 6);
163		output[3] = input[2] & 0x3f;
164		Assert(output[0] < 64);
165		Assert(output[1] < 64);
166		Assert(output[2] < 64);
167		Assert(output[3] < 64);
168
169		if (datalength + 4 > targsize)
170			return (-1);
171		target[datalength++] = Base64[output[0]];
172		target[datalength++] = Base64[output[1]];
173		target[datalength++] = Base64[output[2]];
174		target[datalength++] = Base64[output[3]];
175	}
176
177	/* Now we worry about padding. */
178	if (0U != srclength) {
179		/* Get what's left. */
180		input[0] = input[1] = input[2] = '\0';
181		for (i = 0; i < srclength; i++)
182			input[i] = *src++;
183
184		output[0] = (u_int32_t)input[0] >> 2;
185		output[1] = ((u_int32_t)(input[0] & 0x03) << 4) +
186		    ((u_int32_t)input[1] >> 4);
187		output[2] = ((u_int32_t)(input[1] & 0x0f) << 2) +
188		    ((u_int32_t)input[2] >> 6);
189		Assert(output[0] < 64);
190		Assert(output[1] < 64);
191		Assert(output[2] < 64);
192
193		if (datalength + 4 > targsize)
194			return (-1);
195		target[datalength++] = Base64[output[0]];
196		target[datalength++] = Base64[output[1]];
197		if (srclength == 1U)
198			target[datalength++] = Pad64;
199		else
200			target[datalength++] = Base64[output[2]];
201		target[datalength++] = Pad64;
202	}
203	if (datalength >= targsize)
204		return (-1);
205	target[datalength] = '\0';	/*%< Returned value doesn't count \\0. */
206	assert (datalength <= (size_t)INT_MAX);
207	return (int)datalength;
208}
209
210/* skips all whitespace anywhere.
211   converts characters, four at a time, starting at (or after)
212   src from base - 64 numbers into three 8 bit bytes in the target area.
213   it returns the number of data bytes stored at the target, or -1 on error.
214 */
215
216int
217b64_pton(char const *src, u_char *target, size_t targsize)
218{
219	size_t tarindex;
220	int state, ch;
221	char *pos;
222
223	assert(src != NULL);
224	assert(target != NULL);
225
226	state = 0;
227	tarindex = 0;
228
229	while ((ch = (u_char) *src++) != '\0') {
230		if (isspace(ch))	/*%< Skip whitespace anywhere. */
231			continue;
232
233		if (ch == Pad64)
234			break;
235
236		pos = strchr(Base64, ch);
237		if (pos == 0) 		/*%< A non-base64 character. */
238			return (-1);
239
240		switch (state) {
241		case 0:
242			if (target) {
243				if ((size_t)tarindex >= targsize)
244					return (-1);
245				target[tarindex] =
246				    (unsigned char)(pos - Base64) << 2;
247			}
248			state = 1;
249			break;
250		case 1:
251			if (target) {
252				if ((size_t)tarindex + 1 >= targsize)
253					return (-1);
254				target[tarindex] |=
255				    (u_int32_t)(pos - Base64) >> 4;
256				target[tarindex+1]  =
257				    (unsigned char)
258				    (((pos - Base64) & 0x0f) << 4);
259			}
260			tarindex++;
261			state = 2;
262			break;
263		case 2:
264			if (target) {
265				if ((size_t)tarindex + 1 >= targsize)
266					return (-1);
267				target[tarindex] |=
268					(u_int32_t)(pos - Base64) >> 2;
269				target[tarindex+1] =
270				    (unsigned char)
271				    (((pos - Base64) & 0x03) << 6);
272			}
273			tarindex++;
274			state = 3;
275			break;
276		case 3:
277			if (target) {
278				if ((size_t)tarindex >= targsize)
279					return (-1);
280				target[tarindex] |=
281				    (unsigned char)(pos - Base64);
282			}
283			tarindex++;
284			state = 0;
285			break;
286		default:
287			abort();
288		}
289	}
290
291	/*
292	 * We are done decoding Base-64 chars.  Let's see if we ended
293	 * on a byte boundary, and/or with erroneous trailing characters.
294	 */
295
296	if (ch == Pad64) {		/*%< We got a pad char. */
297		ch = *src++;		/*%< Skip it, get next. */
298		switch (state) {
299		case 0:		/*%< Invalid = in first position */
300		case 1:		/*%< Invalid = in second position */
301			return (-1);
302
303		case 2:		/*%< Valid, means one byte of info */
304			/* Skip any number of spaces. */
305			for (; ch != '\0'; ch = (u_char) *src++)
306				if (!isspace(ch))
307					break;
308			/* Make sure there is another trailing = sign. */
309			if (ch != Pad64)
310				return (-1);
311			ch = *src++;		/*%< Skip the = */
312			/* Fall through to "single trailing =" case. */
313			/* FALLTHROUGH */
314
315		case 3:		/*%< Valid, means two bytes of info */
316			/*
317			 * We know this char is an =.  Is there anything but
318			 * whitespace after it?
319			 */
320			for (; ch != '\0'; ch = (u_char) *src++)
321				if (!isspace(ch))
322					return (-1);
323
324			/*
325			 * Now make sure for cases 2 and 3 that the "extra"
326			 * bits that slopped past the last full byte were
327			 * zeros.  If we don't check them, they become a
328			 * subliminal channel.
329			 */
330			if (target && target[tarindex] != 0)
331				return (-1);
332		}
333	} else {
334		/*
335		 * We ended by seeing the end of the string.  Make sure we
336		 * have no partial bytes lying around.
337		 */
338		if (state != 0)
339			return (-1);
340	}
341
342	assert(tarindex <= (size_t)INT_MAX);
343	return (int)tarindex;
344}
345
346/*! \file */
347