1 /*
2  * Copyright (c) 2021-2022, 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 /*
136  * Helper function to check if 2 UUIDs match.
137  */
uuid_match(uint32_t * uuid1,uint32_t * uuid2)138 bool uuid_match(uint32_t *uuid1, uint32_t *uuid2)
139 {
140 	return !memcmp(uuid1, uuid2, sizeof(uint32_t) * 4);
141 }
142 
143 /*
144  * Helper function to copy from one UUID struct to another.
145  */
copy_uuid(uint32_t * to_uuid,uint32_t * from_uuid)146 void copy_uuid(uint32_t *to_uuid, uint32_t *from_uuid)
147 {
148 	to_uuid[0] = from_uuid[0];
149 	to_uuid[1] = from_uuid[1];
150 	to_uuid[2] = from_uuid[2];
151 	to_uuid[3] = from_uuid[3];
152 }
153 
is_null_uuid(uint32_t * uuid)154 bool is_null_uuid(uint32_t *uuid)
155 {
156 	return (uuid[0] == 0 && uuid[1] == 0 &&
157 		uuid[2] == 0 && uuid[3] == 0);
158 }
159