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("$FreeBSD$");
45
46#include <sys/param.h>
47#include <sys/socket.h>
48
49#include <netinet/in.h>
50#include <arpa/inet.h>
51#include <arpa/nameser.h>
52
53#include <ctype.h>
54#include <resolv.h>
55#include <stdio.h>
56#include <stdlib.h>
57#include <string.h>
58
59#define Assert(Cond) if (!(Cond)) abort()
60
61static const char Base64[] =
62	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
63static const char Pad64 = '=';
64
65/* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
66   The following encoding technique is taken from RFC 1521 by Borenstein
67   and Freed.  It is reproduced here in a slightly edited form for
68   convenience.
69
70   A 65-character subset of US-ASCII is used, enabling 6 bits to be
71   represented per printable character. (The extra 65th character, "=",
72   is used to signify a special processing function.)
73
74   The encoding process represents 24-bit groups of input bits as output
75   strings of 4 encoded characters. Proceeding from left to right, a
76   24-bit input group is formed by concatenating 3 8-bit input groups.
77   These 24 bits are then treated as 4 concatenated 6-bit groups, each
78   of which is translated into a single digit in the base64 alphabet.
79
80   Each 6-bit group is used as an index into an array of 64 printable
81   characters. The character referenced by the index is placed in the
82   output string.
83
84                         Table 1: The Base64 Alphabet
85
86      Value Encoding  Value Encoding  Value Encoding  Value Encoding
87          0 A            17 R            34 i            51 z
88          1 B            18 S            35 j            52 0
89          2 C            19 T            36 k            53 1
90          3 D            20 U            37 l            54 2
91          4 E            21 V            38 m            55 3
92          5 F            22 W            39 n            56 4
93          6 G            23 X            40 o            57 5
94          7 H            24 Y            41 p            58 6
95          8 I            25 Z            42 q            59 7
96          9 J            26 a            43 r            60 8
97         10 K            27 b            44 s            61 9
98         11 L            28 c            45 t            62 +
99         12 M            29 d            46 u            63 /
100         13 N            30 e            47 v
101         14 O            31 f            48 w         (pad) =
102         15 P            32 g            49 x
103         16 Q            33 h            50 y
104
105   Special processing is performed if fewer than 24 bits are available
106   at the end of the data being encoded.  A full encoding quantum is
107   always completed at the end of a quantity.  When fewer than 24 input
108   bits are available in an input group, zero bits are added (on the
109   right) to form an integral number of 6-bit groups.  Padding at the
110   end of the data is performed using the '=' character.
111
112   Since all base64 input is an integral number of octets, only the
113         -------------------------------------------------
114   following cases can arise:
115
116       (1) the final quantum of encoding input is an integral
117           multiple of 24 bits; here, the final unit of encoded
118	   output will be an integral multiple of 4 characters
119	   with no "=" padding,
120       (2) the final quantum of encoding input is exactly 8 bits;
121           here, the final unit of encoded output will be two
122	   characters followed by two "=" padding characters, or
123       (3) the final quantum of encoding input is exactly 16 bits;
124           here, the final unit of encoded output will be three
125	   characters followed by one "=" padding character.
126   */
127
128int
129b64_ntop(u_char const *src, size_t srclength, char *target, size_t targsize) {
130	size_t datalength = 0;
131	u_char input[3];
132	u_char output[4];
133	size_t i;
134
135	while (2 < srclength) {
136		input[0] = *src++;
137		input[1] = *src++;
138		input[2] = *src++;
139		srclength -= 3;
140
141		output[0] = input[0] >> 2;
142		output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
143		output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
144		output[3] = input[2] & 0x3f;
145		Assert(output[0] < 64);
146		Assert(output[1] < 64);
147		Assert(output[2] < 64);
148		Assert(output[3] < 64);
149
150		if (datalength + 4 > targsize)
151			return (-1);
152		target[datalength++] = Base64[output[0]];
153		target[datalength++] = Base64[output[1]];
154		target[datalength++] = Base64[output[2]];
155		target[datalength++] = Base64[output[3]];
156	}
157
158	/* Now we worry about padding. */
159	if (0 != srclength) {
160		/* Get what's left. */
161		input[0] = input[1] = input[2] = '\0';
162		for (i = 0; i < srclength; i++)
163			input[i] = *src++;
164
165		output[0] = input[0] >> 2;
166		output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
167		output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
168		Assert(output[0] < 64);
169		Assert(output[1] < 64);
170		Assert(output[2] < 64);
171
172		if (datalength + 4 > targsize)
173			return (-1);
174		target[datalength++] = Base64[output[0]];
175		target[datalength++] = Base64[output[1]];
176		if (srclength == 1)
177			target[datalength++] = Pad64;
178		else
179			target[datalength++] = Base64[output[2]];
180		target[datalength++] = Pad64;
181	}
182	if (datalength >= targsize)
183		return (-1);
184	target[datalength] = '\0';	/* Returned value doesn't count \0. */
185	return (datalength);
186}
187
188/* skips all whitespace anywhere.
189   converts characters, four at a time, starting at (or after)
190   src from base - 64 numbers into three 8 bit bytes in the target area.
191   it returns the number of data bytes stored at the target, or -1 on error.
192 */
193
194int
195b64_pton(const char *src, u_char *target, size_t targsize)
196{
197	int tarindex, state, ch;
198	u_char nextbyte;
199	char *pos;
200
201	state = 0;
202	tarindex = 0;
203
204	while ((ch = *src++) != '\0') {
205		if (isspace((unsigned char)ch))        /* Skip whitespace anywhere. */
206			continue;
207
208		if (ch == Pad64)
209			break;
210
211		pos = strchr(Base64, ch);
212		if (pos == NULL)		/* A non-base64 character. */
213			return (-1);
214
215		switch (state) {
216		case 0:
217			if (target) {
218				if ((size_t)tarindex >= targsize)
219					return (-1);
220				target[tarindex] = (pos - Base64) << 2;
221			}
222			state = 1;
223			break;
224		case 1:
225			if (target) {
226				if ((size_t)tarindex >= targsize)
227					return (-1);
228				target[tarindex]   |=  (pos - Base64) >> 4;
229				nextbyte = ((pos - Base64) & 0x0f) << 4;
230				if ((size_t)tarindex + 1 < targsize)
231					target[tarindex + 1] = nextbyte;
232				else if (nextbyte)
233					return (-1);
234			}
235			tarindex++;
236			state = 2;
237			break;
238		case 2:
239			if (target) {
240				if ((size_t)tarindex >= targsize)
241					return (-1);
242				target[tarindex]   |=  (pos - Base64) >> 2;
243				nextbyte = ((pos - Base64) & 0x03) << 6;
244				if ((size_t)tarindex + 1 < targsize)
245					target[tarindex + 1] = nextbyte;
246				else if (nextbyte)
247					return (-1);
248			}
249			tarindex++;
250			state = 3;
251			break;
252		case 3:
253			if (target) {
254				if ((size_t)tarindex >= targsize)
255					return (-1);
256				target[tarindex] |= (pos - Base64);
257			}
258			tarindex++;
259			state = 0;
260			break;
261		default:
262			abort();
263		}
264	}
265
266	/*
267	 * We are done decoding Base-64 chars.  Let's see if we ended
268	 * on a byte boundary, and/or with erroneous trailing characters.
269	 */
270
271	if (ch == Pad64) {		/* We got a pad char. */
272		ch = *src++;		/* Skip it, get next. */
273		switch (state) {
274		case 0:		/* Invalid = in first position */
275		case 1:		/* Invalid = in second position */
276			return (-1);
277
278		case 2:		/* Valid, means one byte of info */
279			/* Skip any number of spaces. */
280			for ((void)NULL; ch != '\0'; ch = *src++)
281				if (!isspace((unsigned char)ch))
282					break;
283			/* Make sure there is another trailing = sign. */
284			if (ch != Pad64)
285				return (-1);
286			ch = *src++;		/* Skip the = */
287			/* Fall through to "single trailing =" case. */
288			/* FALLTHROUGH */
289
290		case 3:		/* Valid, means two bytes of info */
291			/*
292			 * We know this char is an =.  Is there anything but
293			 * whitespace after it?
294			 */
295			for ((void)NULL; ch != '\0'; ch = *src++)
296				if (!isspace((unsigned char)ch))
297					return (-1);
298
299			/*
300			 * Now make sure for cases 2 and 3 that the "extra"
301			 * bits that slopped past the last full byte were
302			 * zeros.  If we don't check them, they become a
303			 * subliminal channel.
304			 */
305			if (target && (size_t)tarindex < targsize &&
306			    target[tarindex] != 0)
307				return (-1);
308		}
309	} else {
310		/*
311		 * We ended by seeing the end of the string.  Make sure we
312		 * have no partial bytes lying around.
313		 */
314		if (state != 0)
315			return (-1);
316	}
317
318	return (tarindex);
319}
320