base32.c revision 258945 
1/*
2 * Copyright (C) 2008, 2009  Internet Systems Consortium, Inc. ("ISC")
3 *
4 * Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
9 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
10 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
11 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
12 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
13 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
14 * PERFORMANCE OF THIS SOFTWARE.
15 */
16
17/* $Id: base32.c,v 1.3.116.2 2009/01/18 23:47:41 tbox Exp $ */
18
19/*! \file */
20
21#include <config.h>
22
23#include <isc/base32.h>
24#include <isc/buffer.h>
25#include <isc/lex.h>
26#include <isc/region.h>
27#include <isc/string.h>
28#include <isc/util.h>
29
30#define RETERR(x) do { \
31	isc_result_t _r = (x); \
32	if (_r != ISC_R_SUCCESS) \
33		return (_r); \
34	} while (0)
35
36
37/*@{*/
38/*!
39 * These static functions are also present in lib/dns/rdata.c.  I'm not
40 * sure where they should go. -- bwelling
41 */
42static isc_result_t
43str_totext(const char *source, isc_buffer_t *target);
44
45static isc_result_t
46mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length);
47
48/*@}*/
49
50static const char base32[] =
51	 "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567=abcdefghijklmnopqrstuvwxyz234567";
52static const char base32hex[] =
53	"0123456789ABCDEFGHIJKLMNOPQRSTUV=0123456789abcdefghijklmnopqrstuv";
54
55static isc_result_t
56base32_totext(isc_region_t *source, int wordlength, const char *wordbreak,
57	      isc_buffer_t *target, const char base[])
58{
59	char buf[9];
60	unsigned int loops = 0;
61
62	if (wordlength >= 0 && wordlength < 8)
63		wordlength = 8;
64
65	memset(buf, 0, sizeof(buf));
66	while (source->length > 0) {
67		buf[0] = base[((source->base[0]>>3)&0x1f)];	/* 5 + */
68		if (source->length == 1) {
69			buf[1] = base[(source->base[0]<<2)&0x1c];
70			buf[2] = buf[3] = buf[4] = '=';
71			buf[5] = buf[6] = buf[7] = '=';
72			RETERR(str_totext(buf, target));
73			break;
74		}
75		buf[1] = base[((source->base[0]<<2)&0x1c)|	/* 3 = 8 */
76			      ((source->base[1]>>6)&0x03)];	/* 2 + */
77		buf[2] = base[((source->base[1]>>1)&0x1f)];	/* 5 + */
78		if (source->length == 2) {
79			buf[3] = base[(source->base[1]<<4)&0x10];
80			buf[4] = buf[5] = buf[6] = buf[7] = '=';
81			RETERR(str_totext(buf, target));
82			break;
83		}
84		buf[3] = base[((source->base[1]<<4)&0x10)|	/* 1 = 8 */
85			      ((source->base[2]>>4)&0x0f)];	/* 4 + */
86		if (source->length == 3) {
87			buf[4] = base[(source->base[2]<<1)&0x1e];
88			buf[5] = buf[6] = buf[7] = '=';
89			RETERR(str_totext(buf, target));
90			break;
91		}
92		buf[4] = base[((source->base[2]<<1)&0x1e)|	/* 4 = 8 */
93			      ((source->base[3]>>7)&0x01)];	/* 1 + */
94		buf[5] = base[((source->base[3]>>2)&0x1f)];	/* 5 + */
95		if (source->length == 4) {
96			buf[6] = base[(source->base[3]<<3)&0x18];
97			buf[7] = '=';
98			RETERR(str_totext(buf, target));
99			break;
100		}
101		buf[6] = base[((source->base[3]<<3)&0x18)|	/* 2 = 8 */
102			      ((source->base[4]>>5)&0x07)];	/* 3 + */
103		buf[7] = base[source->base[4]&0x1f];		/* 5 = 8 */
104		RETERR(str_totext(buf, target));
105		isc_region_consume(source, 5);
106
107		loops++;
108		if (source->length != 0 && wordlength >= 0 &&
109		    (int)((loops + 1) * 8) >= wordlength)
110		{
111			loops = 0;
112			RETERR(str_totext(wordbreak, target));
113		}
114	}
115	return (ISC_R_SUCCESS);
116}
117
118isc_result_t
119isc_base32_totext(isc_region_t *source, int wordlength,
120		  const char *wordbreak, isc_buffer_t *target)
121{
122	return (base32_totext(source, wordlength, wordbreak, target, base32));
123}
124
125isc_result_t
126isc_base32hex_totext(isc_region_t *source, int wordlength,
127		     const char *wordbreak, isc_buffer_t *target)
128{
129	return (base32_totext(source, wordlength, wordbreak, target,
130			      base32hex));
131}
132
133/*%
134 * State of a base32 decoding process in progress.
135 */
136typedef struct {
137	int length;		/*%< Desired length of binary data or -1 */
138	isc_buffer_t *target;	/*%< Buffer for resulting binary data */
139	int digits;		/*%< Number of buffered base32 digits */
140	isc_boolean_t seen_end;	/*%< True if "=" end marker seen */
141	int val[8];
142	const char *base;	/*%< Which encoding we are using */
143	int seen_32;		/*%< Number of significant bytes if non zero */
144} base32_decode_ctx_t;
145
146static inline void
147base32_decode_init(base32_decode_ctx_t *ctx, int length,
148		   const char base[], isc_buffer_t *target)
149{
150	ctx->digits = 0;
151	ctx->seen_end = ISC_FALSE;
152	ctx->seen_32 = 0;
153	ctx->length = length;
154	ctx->target = target;
155	ctx->base = base;
156}
157
158static inline isc_result_t
159base32_decode_char(base32_decode_ctx_t *ctx, int c) {
160	char *s;
161	unsigned int last;
162
163	if (ctx->seen_end)
164		return (ISC_R_BADBASE32);
165	if ((s = strchr(ctx->base, c)) == NULL)
166		return (ISC_R_BADBASE32);
167	last = s - ctx->base;
168	/*
169	 * Handle lower case.
170	 */
171	if (last > 32)
172		last -= 33;
173	/*
174	 * Check that padding is contiguous.
175	 */
176	if (last != 32 && ctx->seen_32 != 0)
177		return (ISC_R_BADBASE32);
178	/*
179	 * Check that padding starts at the right place and that
180	 * bits that should be zero are.
181	 * Record how many significant bytes in answer (seen_32).
182	 */
183	if (last == 32 && ctx->seen_32 == 0)
184		switch (ctx->digits) {
185		case 0:
186		case 1:
187			return (ISC_R_BADBASE32);
188		case 2:
189			if ((ctx->val[1]&0x03) != 0)
190				return (ISC_R_BADBASE32);
191			ctx->seen_32 = 1;
192			break;
193		case 3:
194			return (ISC_R_BADBASE32);
195		case 4:
196			if ((ctx->val[3]&0x0f) != 0)
197				return (ISC_R_BADBASE32);
198			ctx->seen_32 = 3;
199			break;
200		case 5:
201			if ((ctx->val[4]&0x01) != 0)
202				return (ISC_R_BADBASE32);
203			ctx->seen_32 = 3;
204			break;
205		case 6:
206			return (ISC_R_BADBASE32);
207		case 7:
208			if ((ctx->val[6]&0x07) != 0)
209				return (ISC_R_BADBASE32);
210			ctx->seen_32 = 4;
211			break;
212		}
213	/*
214	 * Zero fill pad values.
215	 */
216	ctx->val[ctx->digits++] = (last == 32) ? 0 : last;
217
218	if (ctx->digits == 8) {
219		int n = 5;
220		unsigned char buf[5];
221
222		if (ctx->seen_32 != 0) {
223			ctx->seen_end = ISC_TRUE;
224			n = ctx->seen_32;
225		}
226		buf[0] = (ctx->val[0]<<3)|(ctx->val[1]>>2);
227		buf[1] = (ctx->val[1]<<6)|(ctx->val[2]<<1)|(ctx->val[3]>>4);
228		buf[2] = (ctx->val[3]<<4)|(ctx->val[4]>>1);
229		buf[3] = (ctx->val[4]<<7)|(ctx->val[5]<<2)|(ctx->val[6]>>3);
230		buf[4] = (ctx->val[6]<<5)|(ctx->val[7]);
231		RETERR(mem_tobuffer(ctx->target, buf, n));
232		if (ctx->length >= 0) {
233			if (n > ctx->length)
234				return (ISC_R_BADBASE32);
235			else
236				ctx->length -= n;
237		}
238		ctx->digits = 0;
239	}
240	return (ISC_R_SUCCESS);
241}
242
243static inline isc_result_t
244base32_decode_finish(base32_decode_ctx_t *ctx) {
245	if (ctx->length > 0)
246		return (ISC_R_UNEXPECTEDEND);
247	if (ctx->digits != 0)
248		return (ISC_R_BADBASE32);
249	return (ISC_R_SUCCESS);
250}
251
252static isc_result_t
253base32_tobuffer(isc_lex_t *lexer, const char base[], isc_buffer_t *target,
254		int length)
255{
256	base32_decode_ctx_t ctx;
257	isc_textregion_t *tr;
258	isc_token_t token;
259	isc_boolean_t eol;
260
261	base32_decode_init(&ctx, length, base, target);
262
263	while (!ctx.seen_end && (ctx.length != 0)) {
264		unsigned int i;
265
266		if (length > 0)
267			eol = ISC_FALSE;
268		else
269			eol = ISC_TRUE;
270		RETERR(isc_lex_getmastertoken(lexer, &token,
271					      isc_tokentype_string, eol));
272		if (token.type != isc_tokentype_string)
273			break;
274		tr = &token.value.as_textregion;
275		for (i = 0; i < tr->length; i++)
276			RETERR(base32_decode_char(&ctx, tr->base[i]));
277	}
278	if (ctx.length < 0 && !ctx.seen_end)
279		isc_lex_ungettoken(lexer, &token);
280	RETERR(base32_decode_finish(&ctx));
281	return (ISC_R_SUCCESS);
282}
283
284isc_result_t
285isc_base32_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) {
286	return (base32_tobuffer(lexer, base32, target, length));
287}
288
289isc_result_t
290isc_base32hex_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) {
291	return (base32_tobuffer(lexer, base32hex, target, length));
292}
293
294static isc_result_t
295base32_decodestring(const char *cstr, const char base[], isc_buffer_t *target) {
296	base32_decode_ctx_t ctx;
297
298	base32_decode_init(&ctx, -1, base, target);
299	for (;;) {
300		int c = *cstr++;
301		if (c == '\0')
302			break;
303		if (c == ' ' || c == '\t' || c == '\n' || c== '\r')
304			continue;
305		RETERR(base32_decode_char(&ctx, c));
306	}
307	RETERR(base32_decode_finish(&ctx));
308	return (ISC_R_SUCCESS);
309}
310
311isc_result_t
312isc_base32_decodestring(const char *cstr, isc_buffer_t *target) {
313	return (base32_decodestring(cstr, base32, target));
314}
315
316isc_result_t
317isc_base32hex_decodestring(const char *cstr, isc_buffer_t *target) {
318	return (base32_decodestring(cstr, base32hex, target));
319}
320
321static isc_result_t
322base32_decoderegion(isc_region_t *source, const char base[], isc_buffer_t *target) {
323	base32_decode_ctx_t ctx;
324
325	base32_decode_init(&ctx, -1, base, target);
326	while (source->length != 0) {
327		int c = *source->base;
328		RETERR(base32_decode_char(&ctx, c));
329		isc_region_consume(source, 1);
330	}
331	RETERR(base32_decode_finish(&ctx));
332	return (ISC_R_SUCCESS);
333}
334
335isc_result_t
336isc_base32_decoderegion(isc_region_t *source, isc_buffer_t *target) {
337	return (base32_decoderegion(source, base32, target));
338}
339
340isc_result_t
341isc_base32hex_decoderegion(isc_region_t *source, isc_buffer_t *target) {
342	return (base32_decoderegion(source, base32hex, target));
343}
344
345static isc_result_t
346str_totext(const char *source, isc_buffer_t *target) {
347	unsigned int l;
348	isc_region_t region;
349
350	isc_buffer_availableregion(target, &region);
351	l = strlen(source);
352
353	if (l > region.length)
354		return (ISC_R_NOSPACE);
355
356	memcpy(region.base, source, l);
357	isc_buffer_add(target, l);
358	return (ISC_R_SUCCESS);
359}
360
361static isc_result_t
362mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length) {
363	isc_region_t tr;
364
365	isc_buffer_availableregion(target, &tr);
366	if (length > tr.length)
367		return (ISC_R_NOSPACE);
368	memcpy(tr.base, base, length);
369	isc_buffer_add(target, length);
370	return (ISC_R_SUCCESS);
371}
372