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
36 static const char hex[] = "0123456789ABCDEF";
37
38 isc_result_t
isc_hex_totext(isc_region_t * source,int wordlength,const char * wordbreak,isc_buffer_t * target)39 isc_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 */
69 typedef 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
76 static inline void
hex_decode_init(hex_decode_ctx_t * ctx,int length,isc_buffer_t * target)77 hex_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
84 static inline isc_result_t
hex_decode_char(hex_decode_ctx_t * ctx,int c)85 hex_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
107 static inline isc_result_t
hex_decode_finish(hex_decode_ctx_t * ctx)108 hex_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
116 isc_result_t
isc_hex_decodestring(const char * cstr,isc_buffer_t * target)117 isc_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