1 /*
2 * Copyright (c) 2021, Arm Limited and Contributors. All rights reserved.
3 *
4 * SPDX-License-Identifier: BSD-3-Clause
5 */
6
7 #include <assert.h>
8 #include <errno.h>
9 #include <stdint.h>
10 #include <string.h>
11
12 #include <common/debug.h>
13 #include <common/uuid.h>
14
15 /* Return the hex nibble value of a char */
hex_val(char hex)16 static int8_t hex_val(char hex)
17 {
18 int8_t val = 0;
19
20 if ((hex >= '0') && (hex <= '9')) {
21 val = (int8_t)(hex - '0');
22 } else if ((hex >= 'a') && (hex <= 'f')) {
23 val = (int8_t)(hex - 'a' + 0xa);
24 } else if ((hex >= 'A') && (hex <= 'F')) {
25 val = (int8_t)(hex - 'A' + 0xa);
26 } else {
27 val = -1;
28 }
29
30 return val;
31 }
32
33 /*
34 * Read hex_src_len hex characters from hex_src, convert to bytes and
35 * store in buffer pointed to by dest
36 */
read_hex(uint8_t * dest,char * hex_src,unsigned int hex_src_len)37 static int read_hex(uint8_t *dest, char *hex_src, unsigned int hex_src_len)
38 {
39 int8_t nibble;
40 uint8_t byte;
41
42 /*
43 * The string length must be a multiple of 2 to represent an
44 * exact number of bytes.
45 */
46 assert((hex_src_len % 2U) == 0U);
47
48 for (unsigned int i = 0U; i < (hex_src_len / 2U); i++) {
49 nibble = 0;
50 byte = 0U;
51
52 nibble = hex_val(hex_src[2U * i]);
53 if (nibble < 0) {
54 return -1;
55 }
56 byte = (uint8_t)nibble;
57 byte <<= 4U;
58
59 nibble = hex_val(hex_src[(2U * i) + 1U]);
60 if (nibble < 0) {
61 return -1;
62 }
63 byte |= (uint8_t)nibble;
64
65 *dest = byte;
66 dest++;
67 }
68
69 return 0;
70 }
71
72 /* Parse UUIDs of the form aabbccdd-eeff-4099-8877-665544332211 */
read_uuid(uint8_t * dest,char * uuid)73 int read_uuid(uint8_t *dest, char *uuid)
74 {
75 int err;
76 uint8_t *dest_start = dest;
77
78 /* Check that we have enough characters */
79 if (strnlen(uuid, UUID_STRING_LENGTH) != UUID_STRING_LENGTH) {
80 WARN("UUID string is too short\n");
81 return -EINVAL;
82 }
83
84 /* aabbccdd */
85 err = read_hex(dest, uuid, 8);
86 uuid += 8;
87 dest += 4;
88
89 /* Check for '-' */
90 err |= ((*uuid == '-') ? 0 : -1);
91 uuid++;
92
93 /* eeff */
94 err |= read_hex(dest, uuid, 4);
95 uuid += 4;
96 dest += 2;
97
98 /* Check for '-' */
99 err |= ((*uuid == '-') ? 0 : -1);
100 uuid++;
101
102 /* 4099 */
103 err |= read_hex(dest, uuid, 4);
104 uuid += 4;
105 dest += 2;
106
107 /* Check for '-' */
108 err |= ((*uuid == '-') ? 0 : -1);
109 uuid++;
110
111 /* 8877 */
112 err |= read_hex(dest, uuid, 4);
113 uuid += 4;
114 dest += 2;
115
116 /* Check for '-' */
117 err |= ((*uuid == '-') ? 0 : -1);
118 uuid++;
119
120 /* 665544332211 */
121 err |= read_hex(dest, uuid, 12);
122 uuid += 12;
123 dest += 6;
124
125 if (err < 0) {
126 WARN("Error parsing UUID\n");
127 /* Clear the buffer on error */
128 memset((void *)dest_start, '\0', UUID_BYTES_LENGTH * sizeof(uint8_t));
129 return -EINVAL;
130 }
131
132 return 0;
133 }
134
135