1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * (C) Copyright 2016
4 * Olliver Schinagl <oliver@schinagl.nl>
5 */
6
7#include <ctype.h>
8#include <stdbool.h>
9#include <stdint.h>
10#include <stdio.h>
11#include <stdlib.h>
12#include <string.h>
13#include <u-boot/crc.h>
14
15#define ARP_HLEN 6 /* Length of hardware address */
16#define ARP_HLEN_ASCII (ARP_HLEN * 2) + (ARP_HLEN - 1) /* with separators */
17#define ARP_HLEN_LAZY (ARP_HLEN * 2) /* separatorless hardware address length */
18
19uint8_t nibble_to_hex(const char *nibble, bool lo)
20{
21	return (strtol(nibble, NULL, 16) << (lo ? 0 : 4)) & (lo ? 0x0f : 0xf0);
22}
23
24int process_mac(const char *mac_address)
25{
26	uint8_t ethaddr[ARP_HLEN + 1] = { 0x00 };
27	uint_fast8_t i = 0;
28
29	while (*mac_address != '\0') {
30		char nibble[2] = { 0x00, '\n' }; /* for strtol */
31
32		nibble[0] = *mac_address++;
33		if (isxdigit(nibble[0])) {
34			if (isupper(nibble[0]))
35				nibble[0] = tolower(nibble[0]);
36			ethaddr[i >> 1] |= nibble_to_hex(nibble, (i % 2) != 0);
37			i++;
38		}
39	}
40
41	for (i = 0; i < ARP_HLEN; i++)
42		printf("%.2x", ethaddr[i]);
43	printf("%.2x\n", crc8(0, ethaddr, ARP_HLEN));
44
45	return 0;
46}
47
48void print_usage(char *cmdname)
49{
50	printf("Usage: %s <mac_address>\n", cmdname);
51	puts("<mac_address> may be with or without separators.");
52	puts("Valid seperators are ':' and '-'.");
53	puts("<mac_address> digits are in base 16.\n");
54}
55
56int main(int argc, char *argv[])
57{
58	if (argc < 2) {
59		print_usage(argv[0]);
60		return 1;
61	}
62
63	if (!((strlen(argv[1]) == ARP_HLEN_ASCII) || (strlen(argv[1]) == ARP_HLEN_LAZY))) {
64		puts("The MAC address is not valid.\n");
65		print_usage(argv[0]);
66		return 1;
67	}
68
69	if (process_mac(argv[1])) {
70		puts("Failed to calculate the MAC's checksum.");
71		return 1;
72	}
73
74	return 0;
75}
76