base32.c revision 1.2 
1/*	$NetBSD: base32.c,v 1.2 2018/08/12 13:02:37 christos Exp $	*/
2
3/*
4 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
5 *
6 * This Source Code Form is subject to the terms of the Mozilla Public
7 * License, v. 2.0. If a copy of the MPL was not distributed with this
8 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
9 *
10 * See the COPYRIGHT file distributed with this work for additional
11 * information regarding copyright ownership.
12 */
13
14
15/*! \file */
16
17#include <config.h>
18
19#include <isc/base32.h>
20#include <isc/buffer.h>
21#include <isc/lex.h>
22#include <isc/region.h>
23#include <isc/string.h>
24#include <isc/util.h>
25
26#define RETERR(x) do { \
27	isc_result_t _r = (x); \
28	if (_r != ISC_R_SUCCESS) \
29		return (_r); \
30	} while (/*CONSTCOND*/0)
31
32
33/*@{*/
34/*!
35 * These static functions are also present in lib/dns/rdata.c.  I'm not
36 * sure where they should go. -- bwelling
37 */
38static isc_result_t
39str_totext(const char *source, isc_buffer_t *target);
40
41static isc_result_t
42mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length);
43
44/*@}*/
45
46static const char base32[] =
47	 "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567=abcdefghijklmnopqrstuvwxyz234567";
48static const char base32hex[] =
49	"0123456789ABCDEFGHIJKLMNOPQRSTUV=0123456789abcdefghijklmnopqrstuv";
50
51static isc_result_t
52base32_totext(isc_region_t *source, int wordlength, const char *wordbreak,
53	      isc_buffer_t *target, const char base[], char pad)
54{
55	char buf[9];
56	unsigned int loops = 0;
57
58	if (wordlength >= 0 && wordlength < 8)
59		wordlength = 8;
60
61	memset(buf, 0, sizeof(buf));
62	while (source->length > 0) {
63		buf[0] = base[((source->base[0]>>3)&0x1f)];	/* 5 + */
64		if (source->length == 1) {
65			buf[1] = base[(source->base[0]<<2)&0x1c];
66			buf[2] = buf[3] = buf[4] = pad;
67			buf[5] = buf[6] = buf[7] = pad;
68			RETERR(str_totext(buf, target));
69			break;
70		}
71		buf[1] = base[((source->base[0]<<2)&0x1c)|	/* 3 = 8 */
72			      ((source->base[1]>>6)&0x03)];	/* 2 + */
73		buf[2] = base[((source->base[1]>>1)&0x1f)];	/* 5 + */
74		if (source->length == 2) {
75			buf[3] = base[(source->base[1]<<4)&0x10];
76			buf[4] = buf[5] = buf[6] = buf[7] = pad;
77			RETERR(str_totext(buf, target));
78			break;
79		}
80		buf[3] = base[((source->base[1]<<4)&0x10)|	/* 1 = 8 */
81			      ((source->base[2]>>4)&0x0f)];	/* 4 + */
82		if (source->length == 3) {
83			buf[4] = base[(source->base[2]<<1)&0x1e];
84			buf[5] = buf[6] = buf[7] = pad;
85			RETERR(str_totext(buf, target));
86			break;
87		}
88		buf[4] = base[((source->base[2]<<1)&0x1e)|	/* 4 = 8 */
89			      ((source->base[3]>>7)&0x01)];	/* 1 + */
90		buf[5] = base[((source->base[3]>>2)&0x1f)];	/* 5 + */
91		if (source->length == 4) {
92			buf[6] = base[(source->base[3]<<3)&0x18];
93			buf[7] = pad;
94			RETERR(str_totext(buf, target));
95			break;
96		}
97		buf[6] = base[((source->base[3]<<3)&0x18)|	/* 2 = 8 */
98			      ((source->base[4]>>5)&0x07)];	/* 3 + */
99		buf[7] = base[source->base[4]&0x1f];		/* 5 = 8 */
100		RETERR(str_totext(buf, target));
101		isc_region_consume(source, 5);
102
103		loops++;
104		if (source->length != 0 && wordlength >= 0 &&
105		    (int)((loops + 1) * 8) >= wordlength)
106		{
107			loops = 0;
108			RETERR(str_totext(wordbreak, target));
109		}
110	}
111	if (source->length > 0)
112		isc_region_consume(source, source->length);
113	return (ISC_R_SUCCESS);
114}
115
116isc_result_t
117isc_base32_totext(isc_region_t *source, int wordlength,
118		  const char *wordbreak, isc_buffer_t *target)
119{
120	return (base32_totext(source, wordlength, wordbreak, target,
121			      base32, '='));
122}
123
124isc_result_t
125isc_base32hex_totext(isc_region_t *source, int wordlength,
126		     const char *wordbreak, isc_buffer_t *target)
127{
128	return (base32_totext(source, wordlength, wordbreak, target,
129			      base32hex, '='));
130}
131
132isc_result_t
133isc_base32hexnp_totext(isc_region_t *source, int wordlength,
134		     const char *wordbreak, isc_buffer_t *target)
135{
136	return (base32_totext(source, wordlength, wordbreak, target,
137			      base32hex, 0));
138}
139
140/*%
141 * State of a base32 decoding process in progress.
142 */
143typedef struct {
144	int length;		/*%< Desired length of binary data or -1 */
145	isc_buffer_t *target;	/*%< Buffer for resulting binary data */
146	int digits;		/*%< Number of buffered base32 digits */
147	isc_boolean_t seen_end;	/*%< True if "=" end marker seen */
148	int val[8];
149	const char *base;	/*%< Which encoding we are using */
150	int seen_32;		/*%< Number of significant bytes if non zero */
151	isc_boolean_t pad;	/*%< Expect padding */
152} base32_decode_ctx_t;
153
154static inline void
155base32_decode_init(base32_decode_ctx_t *ctx, int length, const char base[],
156		   isc_boolean_t pad, isc_buffer_t *target)
157{
158	ctx->digits = 0;
159	ctx->seen_end = ISC_FALSE;
160	ctx->seen_32 = 0;
161	ctx->length = length;
162	ctx->target = target;
163	ctx->base = base;
164	ctx->pad = pad;
165}
166
167static inline isc_result_t
168base32_decode_char(base32_decode_ctx_t *ctx, int c) {
169	const char *s;
170	unsigned int last;
171
172	if (ctx->seen_end)
173		return (ISC_R_BADBASE32);
174	if ((s = strchr(ctx->base, c)) == NULL)
175		return (ISC_R_BADBASE32);
176	last = (unsigned int)(s - ctx->base);
177
178	/*
179	 * Handle lower case.
180	 */
181	if (last > 32)
182		last -= 33;
183
184	/*
185	 * Check that padding is contiguous.
186	 */
187	if (last != 32 && ctx->seen_32 != 0)
188		return (ISC_R_BADBASE32);
189
190	/*
191	 * If padding is not permitted flag padding as a error.
192	 */
193	if (last == 32 && !ctx->pad)
194		return (ISC_R_BADBASE32);
195
196	/*
197	 * Check that padding starts at the right place and that
198	 * bits that should be zero are.
199	 * Record how many significant bytes in answer (seen_32).
200	 */
201	if (last == 32 && ctx->seen_32 == 0)
202		switch (ctx->digits) {
203		case 0:
204		case 1:
205			return (ISC_R_BADBASE32);
206		case 2:
207			if ((ctx->val[1]&0x03) != 0)
208				return (ISC_R_BADBASE32);
209			ctx->seen_32 = 1;
210			break;
211		case 3:
212			return (ISC_R_BADBASE32);
213		case 4:
214			if ((ctx->val[3]&0x0f) != 0)
215				return (ISC_R_BADBASE32);
216			ctx->seen_32 = 3;
217			break;
218		case 5:
219			if ((ctx->val[4]&0x01) != 0)
220				return (ISC_R_BADBASE32);
221			ctx->seen_32 = 3;
222			break;
223		case 6:
224			return (ISC_R_BADBASE32);
225		case 7:
226			if ((ctx->val[6]&0x07) != 0)
227				return (ISC_R_BADBASE32);
228			ctx->seen_32 = 4;
229			break;
230		}
231
232	/*
233	 * Zero fill pad values.
234	 */
235	ctx->val[ctx->digits++] = (last == 32) ? 0 : last;
236
237	if (ctx->digits == 8) {
238		int n = 5;
239		unsigned char buf[5];
240
241		if (ctx->seen_32 != 0) {
242			ctx->seen_end = ISC_TRUE;
243			n = ctx->seen_32;
244		}
245		buf[0] = (ctx->val[0]<<3)|(ctx->val[1]>>2);
246		buf[1] = (ctx->val[1]<<6)|(ctx->val[2]<<1)|(ctx->val[3]>>4);
247		buf[2] = (ctx->val[3]<<4)|(ctx->val[4]>>1);
248		buf[3] = (ctx->val[4]<<7)|(ctx->val[5]<<2)|(ctx->val[6]>>3);
249		buf[4] = (ctx->val[6]<<5)|(ctx->val[7]);
250		RETERR(mem_tobuffer(ctx->target, buf, n));
251		if (ctx->length >= 0) {
252			if (n > ctx->length)
253				return (ISC_R_BADBASE32);
254			else
255				ctx->length -= n;
256		}
257		ctx->digits = 0;
258	}
259	return (ISC_R_SUCCESS);
260}
261
262static inline isc_result_t
263base32_decode_finish(base32_decode_ctx_t *ctx) {
264
265	if (ctx->length > 0)
266		return (ISC_R_UNEXPECTEDEND);
267	/*
268	 * Add missing padding if required.
269	 */
270	if (!ctx->pad && ctx->digits != 0) {
271		ctx->pad = ISC_TRUE;
272		do {
273			RETERR(base32_decode_char(ctx, '='));
274		} while (ctx->digits != 0);
275	}
276	if (ctx->digits != 0)
277		return (ISC_R_BADBASE32);
278	return (ISC_R_SUCCESS);
279}
280
281static isc_result_t
282base32_tobuffer(isc_lex_t *lexer, const char base[], isc_boolean_t pad,
283		isc_buffer_t *target, int length)
284{
285	base32_decode_ctx_t ctx;
286	isc_textregion_t *tr;
287	isc_token_t token;
288	isc_boolean_t eol;
289
290	base32_decode_init(&ctx, length, base, pad, target);
291
292	while (!ctx.seen_end && (ctx.length != 0)) {
293		unsigned int i;
294
295		if (length > 0)
296			eol = ISC_FALSE;
297		else
298			eol = ISC_TRUE;
299		RETERR(isc_lex_getmastertoken(lexer, &token,
300					      isc_tokentype_string, eol));
301		if (token.type != isc_tokentype_string)
302			break;
303		tr = &token.value.as_textregion;
304		for (i = 0; i < tr->length; i++)
305			RETERR(base32_decode_char(&ctx, tr->base[i]));
306	}
307	if (ctx.length < 0 && !ctx.seen_end)
308		isc_lex_ungettoken(lexer, &token);
309	RETERR(base32_decode_finish(&ctx));
310	return (ISC_R_SUCCESS);
311}
312
313isc_result_t
314isc_base32_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) {
315	return (base32_tobuffer(lexer, base32, ISC_TRUE, target, length));
316}
317
318isc_result_t
319isc_base32hex_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) {
320	return (base32_tobuffer(lexer, base32hex, ISC_TRUE, target, length));
321}
322
323isc_result_t
324isc_base32hexnp_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) {
325	return (base32_tobuffer(lexer, base32hex, ISC_FALSE, target, length));
326}
327
328static isc_result_t
329base32_decodestring(const char *cstr, const char base[], isc_boolean_t pad,
330		    isc_buffer_t *target)
331{
332	base32_decode_ctx_t ctx;
333
334	base32_decode_init(&ctx, -1, base, pad, target);
335	for (;;) {
336		int c = *cstr++;
337		if (c == '\0')
338			break;
339		if (c == ' ' || c == '\t' || c == '\n' || c== '\r')
340			continue;
341		RETERR(base32_decode_char(&ctx, c));
342	}
343	RETERR(base32_decode_finish(&ctx));
344	return (ISC_R_SUCCESS);
345}
346
347isc_result_t
348isc_base32_decodestring(const char *cstr, isc_buffer_t *target) {
349	return (base32_decodestring(cstr, base32, ISC_TRUE, target));
350}
351
352isc_result_t
353isc_base32hex_decodestring(const char *cstr, isc_buffer_t *target) {
354	return (base32_decodestring(cstr, base32hex, ISC_TRUE, target));
355}
356
357isc_result_t
358isc_base32hexnp_decodestring(const char *cstr, isc_buffer_t *target) {
359	return (base32_decodestring(cstr, base32hex, ISC_FALSE, target));
360}
361
362static isc_result_t
363base32_decoderegion(isc_region_t *source, const char base[],
364		    isc_boolean_t pad, isc_buffer_t *target)
365{
366	base32_decode_ctx_t ctx;
367
368	base32_decode_init(&ctx, -1, base, pad, target);
369	while (source->length != 0) {
370		int c = *source->base;
371		RETERR(base32_decode_char(&ctx, c));
372		isc_region_consume(source, 1);
373	}
374	RETERR(base32_decode_finish(&ctx));
375	return (ISC_R_SUCCESS);
376}
377
378isc_result_t
379isc_base32_decoderegion(isc_region_t *source, isc_buffer_t *target) {
380	return (base32_decoderegion(source, base32, ISC_TRUE, target));
381}
382
383isc_result_t
384isc_base32hex_decoderegion(isc_region_t *source, isc_buffer_t *target) {
385	return (base32_decoderegion(source, base32hex, ISC_TRUE, target));
386}
387
388isc_result_t
389isc_base32hexnp_decoderegion(isc_region_t *source, isc_buffer_t *target) {
390	return (base32_decoderegion(source, base32hex, ISC_FALSE, target));
391}
392
393static isc_result_t
394str_totext(const char *source, isc_buffer_t *target) {
395	unsigned int l;
396	isc_region_t region;
397
398	isc_buffer_availableregion(target, &region);
399	l = strlen(source);
400
401	if (l > region.length)
402		return (ISC_R_NOSPACE);
403
404	memmove(region.base, source, l);
405	isc_buffer_add(target, l);
406	return (ISC_R_SUCCESS);
407}
408
409static isc_result_t
410mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length) {
411	isc_region_t tr;
412
413	isc_buffer_availableregion(target, &tr);
414	if (length > tr.length)
415		return (ISC_R_NOSPACE);
416	memmove(tr.base, base, length);
417	isc_buffer_add(target, length);
418	return (ISC_R_SUCCESS);
419}
420