hex.c revision 1.4 
1/*
2 * Copyright (C) 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: hex.c,v 1.4 2020/02/26 18:47:25 florian Exp $ */
18
19/*! \file */
20
21#include <ctype.h>
22#include <string.h>
23
24#include <isc/buffer.h>
25#include <isc/hex.h>
26#include <isc/region.h>
27#include <isc/types.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 * BEW: These static functions are copied from lib/dns/rdata.c.
38 */
39static isc_result_t
40str_totext(const char *source, isc_buffer_t *target);
41
42static const char hex[] = "0123456789ABCDEF";
43
44isc_result_t
45isc_hex_totext(isc_region_t *source, int wordlength,
46	       const char *wordbreak, isc_buffer_t *target)
47{
48	char buf[3];
49	unsigned int loops = 0;
50
51	if (wordlength < 2)
52		wordlength = 2;
53
54	memset(buf, 0, sizeof(buf));
55	while (source->length > 0) {
56		buf[0] = hex[(source->base[0] >> 4) & 0xf];
57		buf[1] = hex[(source->base[0]) & 0xf];
58		RETERR(str_totext(buf, target));
59		isc_region_consume(source, 1);
60
61		loops++;
62		if (source->length != 0 &&
63		    (int)((loops + 1) * 2) >= wordlength)
64		{
65			loops = 0;
66			RETERR(str_totext(wordbreak, target));
67		}
68	}
69	return (ISC_R_SUCCESS);
70}
71
72/*%
73 * State of a hex decoding process in progress.
74 */
75typedef struct {
76	int length;		/*%< Desired length of binary data or -1 */
77	isc_buffer_t *target;	/*%< Buffer for resulting binary data */
78	int digits;		/*%< Number of buffered hex digits */
79	int val[2];
80} hex_decode_ctx_t;
81
82static inline void
83hex_decode_init(hex_decode_ctx_t *ctx, int length, isc_buffer_t *target)
84{
85	ctx->digits = 0;
86	ctx->length = length;
87	ctx->target = target;
88}
89
90static inline isc_result_t
91hex_decode_char(hex_decode_ctx_t *ctx, int c) {
92	const char *s;
93
94	if ((s = strchr(hex, toupper(c))) == NULL)
95		return (ISC_R_BADHEX);
96	ctx->val[ctx->digits++] = (int)(s - hex);
97	if (ctx->digits == 2) {
98		unsigned char num;
99
100		num = (ctx->val[0] << 4) + (ctx->val[1]);
101		RETERR(isc_mem_tobuffer(ctx->target, &num, 1));
102		if (ctx->length >= 0) {
103			if (ctx->length == 0)
104				return (ISC_R_BADHEX);
105			else
106				ctx->length -= 1;
107		}
108		ctx->digits = 0;
109	}
110	return (ISC_R_SUCCESS);
111}
112
113static inline isc_result_t
114hex_decode_finish(hex_decode_ctx_t *ctx) {
115	if (ctx->length > 0)
116		return (ISC_R_UNEXPECTEDEND);
117	if (ctx->digits != 0)
118		return (ISC_R_BADHEX);
119	return (ISC_R_SUCCESS);
120}
121
122isc_result_t
123isc_hex_decodestring(const char *cstr, isc_buffer_t *target) {
124	hex_decode_ctx_t ctx;
125
126	hex_decode_init(&ctx, -1, target);
127	for (;;) {
128		int c = *cstr++;
129		if (c == '\0')
130			break;
131		if (c == ' ' || c == '\t' || c == '\n' || c== '\r')
132			continue;
133		RETERR(hex_decode_char(&ctx, c));
134	}
135	RETERR(hex_decode_finish(&ctx));
136	return (ISC_R_SUCCESS);
137}
138
139static isc_result_t
140str_totext(const char *source, isc_buffer_t *target) {
141	unsigned int l;
142	isc_region_t region;
143
144	isc_buffer_availableregion(target, &region);
145	l = strlen(source);
146
147	if (l > region.length)
148		return (ISC_R_NOSPACE);
149
150	memmove(region.base, source, l);
151	isc_buffer_add(target, l);
152	return (ISC_R_SUCCESS);
153}
154