1/*	$NetBSD: base32.c,v 1.6 2020/05/25 20:47:20 christos Exp $	*/
2
3/*
4 * Copyright (C) 2008, 2009  Internet Systems Consortium, Inc. ("ISC")
5 *
6 * Permission to use, copy, modify, and/or distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
11 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
12 * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
13 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
14 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
15 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
16 * PERFORMANCE OF THIS SOFTWARE.
17 */
18
19/* Id: base32.c,v 1.6 2009/10/21 01:22:29 each Exp  */
20
21/*! \file */
22
23#include <config.h>
24
25#include <isc/base32.h>
26#include <isc/buffer.h>
27#include <isc/lex.h>
28#include <isc/region.h>
29#include <isc/string.h>
30#include <isc/util.h>
31
32#define RETERR(x) do { \
33	isc_result_t _r = (x); \
34	if (_r != ISC_R_SUCCESS) \
35		return (_r); \
36	} while (0)
37
38
39/*@{*/
40/*!
41 * These static functions are also present in lib/dns/rdata.c.  I'm not
42 * sure where they should go. -- bwelling
43 */
44static isc_result_t
45str_totext(const char *source, isc_buffer_t *target);
46
47static isc_result_t
48mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length);
49
50/*@}*/
51
52static const char base32[] =
53	 "ABCDEFGHIJKLMNOPQRSTUVWXYZ234567=abcdefghijklmnopqrstuvwxyz234567";
54static const char base32hex[] =
55	"0123456789ABCDEFGHIJKLMNOPQRSTUV=0123456789abcdefghijklmnopqrstuv";
56
57static isc_result_t
58base32_totext(isc_region_t *source, int wordlength, const char *wordbreak,
59	      isc_buffer_t *target, const char base[])
60{
61	char buf[9];
62	unsigned int loops = 0;
63
64	if (wordlength >= 0 && wordlength < 8)
65		wordlength = 8;
66
67	memset(buf, 0, sizeof(buf));
68	while (source->length > 0) {
69		buf[0] = base[((source->base[0]>>3)&0x1f)];	/* 5 + */
70		if (source->length == 1) {
71			buf[1] = base[(source->base[0]<<2)&0x1c];
72			buf[2] = buf[3] = buf[4] = '=';
73			buf[5] = buf[6] = buf[7] = '=';
74			RETERR(str_totext(buf, target));
75			break;
76		}
77		buf[1] = base[((source->base[0]<<2)&0x1c)|	/* 3 = 8 */
78			      ((source->base[1]>>6)&0x03)];	/* 2 + */
79		buf[2] = base[((source->base[1]>>1)&0x1f)];	/* 5 + */
80		if (source->length == 2) {
81			buf[3] = base[(source->base[1]<<4)&0x10];
82			buf[4] = buf[5] = buf[6] = buf[7] = '=';
83			RETERR(str_totext(buf, target));
84			break;
85		}
86		buf[3] = base[((source->base[1]<<4)&0x10)|	/* 1 = 8 */
87			      ((source->base[2]>>4)&0x0f)];	/* 4 + */
88		if (source->length == 3) {
89			buf[4] = base[(source->base[2]<<1)&0x1e];
90			buf[5] = buf[6] = buf[7] = '=';
91			RETERR(str_totext(buf, target));
92			break;
93		}
94		buf[4] = base[((source->base[2]<<1)&0x1e)|	/* 4 = 8 */
95			      ((source->base[3]>>7)&0x01)];	/* 1 + */
96		buf[5] = base[((source->base[3]>>2)&0x1f)];	/* 5 + */
97		if (source->length == 4) {
98			buf[6] = base[(source->base[3]<<3)&0x18];
99			buf[7] = '=';
100			RETERR(str_totext(buf, target));
101			break;
102		}
103		buf[6] = base[((source->base[3]<<3)&0x18)|	/* 2 = 8 */
104			      ((source->base[4]>>5)&0x07)];	/* 3 + */
105		buf[7] = base[source->base[4]&0x1f];		/* 5 = 8 */
106		RETERR(str_totext(buf, target));
107		isc_region_consume(source, 5);
108
109		loops++;
110		if (source->length != 0 && wordlength >= 0 &&
111		    (int)((loops + 1) * 8) >= wordlength)
112		{
113			loops = 0;
114			RETERR(str_totext(wordbreak, target));
115		}
116	}
117	if (source->length > 0)
118		isc_region_consume(source, source->length);
119	return (ISC_R_SUCCESS);
120}
121
122isc_result_t
123isc_base32_totext(isc_region_t *source, int wordlength,
124		  const char *wordbreak, isc_buffer_t *target)
125{
126	return (base32_totext(source, wordlength, wordbreak, target, base32));
127}
128
129isc_result_t
130isc_base32hex_totext(isc_region_t *source, int wordlength,
131		     const char *wordbreak, isc_buffer_t *target)
132{
133	return (base32_totext(source, wordlength, wordbreak, target,
134			      base32hex));
135}
136
137/*%
138 * State of a base32 decoding process in progress.
139 */
140typedef struct {
141	int length;		/*%< Desired length of binary data or -1 */
142	isc_buffer_t *target;	/*%< Buffer for resulting binary data */
143	int digits;		/*%< Number of buffered base32 digits */
144	isc_boolean_t seen_end;	/*%< True if "=" end marker seen */
145	int val[8];
146	const char *base;	/*%< Which encoding we are using */
147	int seen_32;		/*%< Number of significant bytes if non zero */
148} base32_decode_ctx_t;
149
150static inline void
151base32_decode_init(base32_decode_ctx_t *ctx, int length,
152		   const char base[], isc_buffer_t *target)
153{
154	ctx->digits = 0;
155	ctx->seen_end = ISC_FALSE;
156	ctx->seen_32 = 0;
157	ctx->length = length;
158	ctx->target = target;
159	ctx->base = base;
160}
161
162static inline isc_result_t
163base32_decode_char(base32_decode_ctx_t *ctx, int c) {
164	char *s;
165	unsigned int last;
166
167	if (ctx->seen_end)
168		return (ISC_R_BADBASE32);
169	if ((s = strchr(ctx->base, c)) == NULL)
170		return (ISC_R_BADBASE32);
171	last = s - ctx->base;
172	/*
173	 * Handle lower case.
174	 */
175	if (last > 32)
176		last -= 33;
177	/*
178	 * Check that padding is contiguous.
179	 */
180	if (last != 32 && ctx->seen_32 != 0)
181		return (ISC_R_BADBASE32);
182	/*
183	 * Check that padding starts at the right place and that
184	 * bits that should be zero are.
185	 * Record how many significant bytes in answer (seen_32).
186	 */
187	if (last == 32 && ctx->seen_32 == 0)
188		switch (ctx->digits) {
189		case 0:
190		case 1:
191			return (ISC_R_BADBASE32);
192		case 2:
193			if ((ctx->val[1]&0x03) != 0)
194				return (ISC_R_BADBASE32);
195			ctx->seen_32 = 1;
196			break;
197		case 3:
198			return (ISC_R_BADBASE32);
199		case 4:
200			if ((ctx->val[3]&0x0f) != 0)
201				return (ISC_R_BADBASE32);
202			ctx->seen_32 = 3;
203			break;
204		case 5:
205			if ((ctx->val[4]&0x01) != 0)
206				return (ISC_R_BADBASE32);
207			ctx->seen_32 = 3;
208			break;
209		case 6:
210			return (ISC_R_BADBASE32);
211		case 7:
212			if ((ctx->val[6]&0x07) != 0)
213				return (ISC_R_BADBASE32);
214			ctx->seen_32 = 4;
215			break;
216		}
217	/*
218	 * Zero fill pad values.
219	 */
220	ctx->val[ctx->digits++] = (last == 32) ? 0 : last;
221
222	if (ctx->digits == 8) {
223		int n = 5;
224		unsigned char buf[5];
225
226		if (ctx->seen_32 != 0) {
227			ctx->seen_end = ISC_TRUE;
228			n = ctx->seen_32;
229		}
230		buf[0] = (ctx->val[0]<<3)|(ctx->val[1]>>2);
231		buf[1] = (ctx->val[1]<<6)|(ctx->val[2]<<1)|(ctx->val[3]>>4);
232		buf[2] = (ctx->val[3]<<4)|(ctx->val[4]>>1);
233		buf[3] = (ctx->val[4]<<7)|(ctx->val[5]<<2)|(ctx->val[6]>>3);
234		buf[4] = (ctx->val[6]<<5)|(ctx->val[7]);
235		RETERR(mem_tobuffer(ctx->target, buf, n));
236		if (ctx->length >= 0) {
237			if (n > ctx->length)
238				return (ISC_R_BADBASE32);
239			else
240				ctx->length -= n;
241		}
242		ctx->digits = 0;
243	}
244	return (ISC_R_SUCCESS);
245}
246
247static inline isc_result_t
248base32_decode_finish(base32_decode_ctx_t *ctx) {
249	if (ctx->length > 0)
250		return (ISC_R_UNEXPECTEDEND);
251	if (ctx->digits != 0)
252		return (ISC_R_BADBASE32);
253	return (ISC_R_SUCCESS);
254}
255
256static isc_result_t
257base32_tobuffer(isc_lex_t *lexer, const char base[], isc_buffer_t *target,
258		int length)
259{
260	base32_decode_ctx_t ctx;
261	isc_textregion_t *tr;
262	isc_token_t token;
263	isc_boolean_t eol;
264
265	base32_decode_init(&ctx, length, base, target);
266
267	while (!ctx.seen_end && (ctx.length != 0)) {
268		unsigned int i;
269
270		if (length > 0)
271			eol = ISC_FALSE;
272		else
273			eol = ISC_TRUE;
274		RETERR(isc_lex_getmastertoken(lexer, &token,
275					      isc_tokentype_string, eol));
276		if (token.type != isc_tokentype_string)
277			break;
278		tr = &token.value.as_textregion;
279		for (i = 0; i < tr->length; i++)
280			RETERR(base32_decode_char(&ctx, tr->base[i]));
281	}
282	if (ctx.length < 0 && !ctx.seen_end)
283		isc_lex_ungettoken(lexer, &token);
284	RETERR(base32_decode_finish(&ctx));
285	return (ISC_R_SUCCESS);
286}
287
288isc_result_t
289isc_base32_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) {
290	return (base32_tobuffer(lexer, base32, target, length));
291}
292
293isc_result_t
294isc_base32hex_tobuffer(isc_lex_t *lexer, isc_buffer_t *target, int length) {
295	return (base32_tobuffer(lexer, base32hex, target, length));
296}
297
298static isc_result_t
299base32_decodestring(const char *cstr, const char base[], isc_buffer_t *target) {
300	base32_decode_ctx_t ctx;
301
302	base32_decode_init(&ctx, -1, base, target);
303	for (;;) {
304		int c = *cstr++;
305		if (c == '\0')
306			break;
307		if (c == ' ' || c == '\t' || c == '\n' || c== '\r')
308			continue;
309		RETERR(base32_decode_char(&ctx, c));
310	}
311	RETERR(base32_decode_finish(&ctx));
312	return (ISC_R_SUCCESS);
313}
314
315isc_result_t
316isc_base32_decodestring(const char *cstr, isc_buffer_t *target) {
317	return (base32_decodestring(cstr, base32, target));
318}
319
320isc_result_t
321isc_base32hex_decodestring(const char *cstr, isc_buffer_t *target) {
322	return (base32_decodestring(cstr, base32hex, target));
323}
324
325static isc_result_t
326base32_decoderegion(isc_region_t *source, const char base[], isc_buffer_t *target) {
327	base32_decode_ctx_t ctx;
328
329	base32_decode_init(&ctx, -1, base, target);
330	while (source->length != 0) {
331		int c = *source->base;
332		RETERR(base32_decode_char(&ctx, c));
333		isc_region_consume(source, 1);
334	}
335	RETERR(base32_decode_finish(&ctx));
336	return (ISC_R_SUCCESS);
337}
338
339isc_result_t
340isc_base32_decoderegion(isc_region_t *source, isc_buffer_t *target) {
341	return (base32_decoderegion(source, base32, target));
342}
343
344isc_result_t
345isc_base32hex_decoderegion(isc_region_t *source, isc_buffer_t *target) {
346	return (base32_decoderegion(source, base32hex, target));
347}
348
349static isc_result_t
350str_totext(const char *source, isc_buffer_t *target) {
351	unsigned int l;
352	isc_region_t region;
353
354	isc_buffer_availableregion(target, &region);
355	l = strlen(source);
356
357	if (l > region.length)
358		return (ISC_R_NOSPACE);
359
360	memcpy(region.base, source, l);
361	isc_buffer_add(target, l);
362	return (ISC_R_SUCCESS);
363}
364
365static isc_result_t
366mem_tobuffer(isc_buffer_t *target, void *base, unsigned int length) {
367	isc_region_t tr;
368
369	isc_buffer_availableregion(target, &tr);
370	if (length > tr.length)
371		return (ISC_R_NOSPACE);
372	memcpy(tr.base, base, length);
373	isc_buffer_add(target, length);
374	return (ISC_R_SUCCESS);
375}
376