base32.c revision 280849 
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 1.6 2009/10/21 01:22:29 each 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	if (source->length > 0)
116		isc_region_consume(source, source->length);
117	return (ISC_R_SUCCESS);
118}
119
120isc_result_t
121isc_base32_totext(isc_region_t *source, int wordlength,
122		  const char *wordbreak, isc_buffer_t *target)
123{
124	return (base32_totext(source, wordlength, wordbreak, target, base32));
125}
126
127isc_result_t
128isc_base32hex_totext(isc_region_t *source, int wordlength,
129		     const char *wordbreak, isc_buffer_t *target)
130{
131	return (base32_totext(source, wordlength, wordbreak, target,
132			      base32hex));
133}
134
135/*%
136 * State of a base32 decoding process in progress.
137 */
138typedef struct {
139	int length;		/*%< Desired length of binary data or -1 */
140	isc_buffer_t *target;	/*%< Buffer for resulting binary data */
141	int digits;		/*%< Number of buffered base32 digits */
142	isc_boolean_t seen_end;	/*%< True if "=" end marker seen */
143	int val[8];
144	const char *base;	/*%< Which encoding we are using */
145	int seen_32;		/*%< Number of significant bytes if non zero */
146} base32_decode_ctx_t;
147
148static inline void
149base32_decode_init(base32_decode_ctx_t *ctx, int length,
150		   const char base[], isc_buffer_t *target)
151{
152	ctx->digits = 0;
153	ctx->seen_end = ISC_FALSE;
154	ctx->seen_32 = 0;
155	ctx->length = length;
156	ctx->target = target;
157	ctx->base = base;
158}
159
160static inline isc_result_t
161base32_decode_char(base32_decode_ctx_t *ctx, int c) {
162	char *s;
163	unsigned int last;
164
165	if (ctx->seen_end)
166		return (ISC_R_BADBASE32);
167	if ((s = strchr(ctx->base, c)) == NULL)
168		return (ISC_R_BADBASE32);
169	last = s - ctx->base;
170	/*
171	 * Handle lower case.
172	 */
173	if (last > 32)
174		last -= 33;
175	/*
176	 * Check that padding is contiguous.
177	 */
178	if (last != 32 && ctx->seen_32 != 0)
179		return (ISC_R_BADBASE32);
180	/*
181	 * Check that padding starts at the right place and that
182	 * bits that should be zero are.
183	 * Record how many significant bytes in answer (seen_32).
184	 */
185	if (last == 32 && ctx->seen_32 == 0)
186		switch (ctx->digits) {
187		case 0:
188		case 1:
189			return (ISC_R_BADBASE32);
190		case 2:
191			if ((ctx->val[1]&0x03) != 0)
192				return (ISC_R_BADBASE32);
193			ctx->seen_32 = 1;
194			break;
195		case 3:
196			return (ISC_R_BADBASE32);
197		case 4:
198			if ((ctx->val[3]&0x0f) != 0)
199				return (ISC_R_BADBASE32);
200			ctx->seen_32 = 3;
201			break;
202		case 5:
203			if ((ctx->val[4]&0x01) != 0)
204				return (ISC_R_BADBASE32);
205			ctx->seen_32 = 3;
206			break;
207		case 6:
208			return (ISC_R_BADBASE32);
209		case 7:
210			if ((ctx->val[6]&0x07) != 0)
211				return (ISC_R_BADBASE32);
212			ctx->seen_32 = 4;
213			break;
214		}
215	/*
216	 * Zero fill pad values.
217	 */
218	ctx->val[ctx->digits++] = (last == 32) ? 0 : last;
219
220	if (ctx->digits == 8) {
221		int n = 5;
222		unsigned char buf[5];
223
224		if (ctx->seen_32 != 0) {
225			ctx->seen_end = ISC_TRUE;
226			n = ctx->seen_32;
227		}
228		buf[0] = (ctx->val[0]<<3)|(ctx->val[1]>>2);
229		buf[1] = (ctx->val[1]<<6)|(ctx->val[2]<<1)|(ctx->val[3]>>4);
230		buf[2] = (ctx->val[3]<<4)|(ctx->val[4]>>1);
231		buf[3] = (ctx->val[4]<<7)|(ctx->val[5]<<2)|(ctx->val[6]>>3);
232		buf[4] = (ctx->val[6]<<5)|(ctx->val[7]);
233		RETERR(mem_tobuffer(ctx->target, buf, n));
234		if (ctx->length >= 0) {
235			if (n > ctx->length)
236				return (ISC_R_BADBASE32);
237			else
238				ctx->length -= n;
239		}
240		ctx->digits = 0;
241	}
242	return (ISC_R_SUCCESS);
243}
244
245static inline isc_result_t
246base32_decode_finish(base32_decode_ctx_t *ctx) {
247	if (ctx->length > 0)
248		return (ISC_R_UNEXPECTEDEND);
249	if (ctx->digits != 0)
250		return (ISC_R_BADBASE32);
251	return (ISC_R_SUCCESS);
252}
253
254static isc_result_t
255base32_tobuffer(isc_lex_t *lexer, const char base[], isc_buffer_t *target,
256		int length)
257{
258	base32_decode_ctx_t ctx;
259	isc_textregion_t *tr;
260	isc_token_t token;
261	isc_boolean_t eol;
262
263	base32_decode_init(&ctx, length, base, target);
264
265	while (!ctx.seen_end && (ctx.length != 0)) {
266		unsigned int i;
267
268		if (length > 0)
269			eol = ISC_FALSE;
270		else
271			eol = ISC_TRUE;
272		RETERR(isc_lex_getmastertoken(lexer, &token,
273					      isc_tokentype_string, eol));
274		if (token.type != isc_tokentype_string)
275			break;
276		tr = &token.value.as_textregion;
277		for (i = 0; i < tr->length; i++)
278			RETERR(base32_decode_char(&ctx, tr->base[i]));
279	}
280	if (ctx.length < 0 && !ctx.seen_end)
281		isc_lex_ungettoken(lexer, &token);
282	RETERR(base32_decode_finish(&ctx));
283	return (ISC_R_SUCCESS);
284}
285
286isc_result_t
287isc_base32_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) {
288	return (base32_tobuffer(lexer, base32, target, length));
289}
290
291isc_result_t
292isc_base32hex_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) {
293	return (base32_tobuffer(lexer, base32hex, target, length));
294}
295
296static isc_result_t
297base32_decodestring(const char *cstr, const char base[], isc_buffer_t *target) {
298	base32_decode_ctx_t ctx;
299
300	base32_decode_init(&ctx, -1, base, target);
301	for (;;) {
302		int c = *cstr++;
303		if (c == '\0')
304			break;
305		if (c == ' ' || c == '\t' || c == '\n' || c== '\r')
306			continue;
307		RETERR(base32_decode_char(&ctx, c));
308	}
309	RETERR(base32_decode_finish(&ctx));
310	return (ISC_R_SUCCESS);
311}
312
313isc_result_t
314isc_base32_decodestring(const char *cstr, isc_buffer_t *target) {
315	return (base32_decodestring(cstr, base32, target));
316}
317
318isc_result_t
319isc_base32hex_decodestring(const char *cstr, isc_buffer_t *target) {
320	return (base32_decodestring(cstr, base32hex, target));
321}
322
323static isc_result_t
324base32_decoderegion(isc_region_t *source, const char base[], isc_buffer_t *target) {
325	base32_decode_ctx_t ctx;
326
327	base32_decode_init(&ctx, -1, base, target);
328	while (source->length != 0) {
329		int c = *source->base;
330		RETERR(base32_decode_char(&ctx, c));
331		isc_region_consume(source, 1);
332	}
333	RETERR(base32_decode_finish(&ctx));
334	return (ISC_R_SUCCESS);
335}
336
337isc_result_t
338isc_base32_decoderegion(isc_region_t *source, isc_buffer_t *target) {
339	return (base32_decoderegion(source, base32, target));
340}
341
342isc_result_t
343isc_base32hex_decoderegion(isc_region_t *source, isc_buffer_t *target) {
344	return (base32_decoderegion(source, base32hex, target));
345}
346
347static isc_result_t
348str_totext(const char *source, isc_buffer_t *target) {
349	unsigned int l;
350	isc_region_t region;
351
352	isc_buffer_availableregion(target, &region);
353	l = strlen(source);
354
355	if (l > region.length)
356		return (ISC_R_NOSPACE);
357
358	memcpy(region.base, source, l);
359	isc_buffer_add(target, l);
360	return (ISC_R_SUCCESS);
361}
362
363static isc_result_t
364mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length) {
365	isc_region_t tr;
366
367	isc_buffer_availableregion(target, &tr);
368	if (length > tr.length)
369		return (ISC_R_NOSPACE);
370	memcpy(tr.base, base, length);
371	isc_buffer_add(target, length);
372	return (ISC_R_SUCCESS);
373}
374