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 1.5 2020/02/26 18:47:59 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
36static const char hex[] = "0123456789ABCDEF";
37
38isc_result_t
39isc_hex_totext(isc_region_t *source, int wordlength,
40	       const char *wordbreak, isc_buffer_t *target)
41{
42	char buf[3];
43	unsigned int loops = 0;
44
45	if (wordlength < 2)
46		wordlength = 2;
47
48	memset(buf, 0, sizeof(buf));
49	while (source->length > 0) {
50		buf[0] = hex[(source->base[0] >> 4) & 0xf];
51		buf[1] = hex[(source->base[0]) & 0xf];
52		RETERR(isc_str_tobuffer(buf, target));
53		isc_region_consume(source, 1);
54
55		loops++;
56		if (source->length != 0 &&
57		    (int)((loops + 1) * 2) >= wordlength)
58		{
59			loops = 0;
60			RETERR(isc_str_tobuffer(wordbreak, target));
61		}
62	}
63	return (ISC_R_SUCCESS);
64}
65
66/*%
67 * State of a hex decoding process in progress.
68 */
69typedef struct {
70	int length;		/*%< Desired length of binary data or -1 */
71	isc_buffer_t *target;	/*%< Buffer for resulting binary data */
72	int digits;		/*%< Number of buffered hex digits */
73	int val[2];
74} hex_decode_ctx_t;
75
76static inline void
77hex_decode_init(hex_decode_ctx_t *ctx, int length, isc_buffer_t *target)
78{
79	ctx->digits = 0;
80	ctx->length = length;
81	ctx->target = target;
82}
83
84static inline isc_result_t
85hex_decode_char(hex_decode_ctx_t *ctx, int c) {
86	const char *s;
87
88	if ((s = strchr(hex, toupper(c))) == NULL)
89		return (ISC_R_BADHEX);
90	ctx->val[ctx->digits++] = (int)(s - hex);
91	if (ctx->digits == 2) {
92		unsigned char num;
93
94		num = (ctx->val[0] << 4) + (ctx->val[1]);
95		RETERR(isc_mem_tobuffer(ctx->target, &num, 1));
96		if (ctx->length >= 0) {
97			if (ctx->length == 0)
98				return (ISC_R_BADHEX);
99			else
100				ctx->length -= 1;
101		}
102		ctx->digits = 0;
103	}
104	return (ISC_R_SUCCESS);
105}
106
107static inline isc_result_t
108hex_decode_finish(hex_decode_ctx_t *ctx) {
109	if (ctx->length > 0)
110		return (ISC_R_UNEXPECTEDEND);
111	if (ctx->digits != 0)
112		return (ISC_R_BADHEX);
113	return (ISC_R_SUCCESS);
114}
115
116isc_result_t
117isc_hex_decodestring(const char *cstr, isc_buffer_t *target) {
118	hex_decode_ctx_t ctx;
119
120	hex_decode_init(&ctx, -1, target);
121	for (;;) {
122		int c = *cstr++;
123		if (c == '\0')
124			break;
125		if (c == ' ' || c == '\t' || c == '\n' || c== '\r')
126			continue;
127		RETERR(hex_decode_char(&ctx, c));
128	}
129	RETERR(hex_decode_finish(&ctx));
130	return (ISC_R_SUCCESS);
131}
132