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e195e0269c
This does two things:
The documentation of `luid_get()` is wrong, or at least confusing.
It talks about
> an 8-bit incrementing counter value into the most significant byte
while the implementation does
((uint8_t *)buf)[0] ^= lastused++; // 0 is LSB!
Now it could be argued that the intention was that the ID is supposed
to be used in Big Endian contexts and that was an omission, however
to keep everyone's sanity, let's keep it simple and just state that this
actually changes the LSB.
Also add a `luid_get_lb()` function that does the same, but modifies the
most significant byte - or the last byte if looking at the index.
This can then be used directly by e.g. #13743
100 lines
1.9 KiB
C
100 lines
1.9 KiB
C
/*
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* Copyright (C) 2017 Freie Universität Berlin
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*
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* This file is subject to the terms and conditions of the GNU Lesser
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* General Public License v2.1. See the file LICENSE in the top level
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* directory for more details.
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*/
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/**
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* @ingroup sys_luid
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* @{
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*
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* @file
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* @brief LUID module implementation
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*
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* @author Hauke Petersen <hauke.petersen@fu-berlin.de>
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*
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* @}
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*/
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#include <stdint.h>
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#include <string.h>
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#include "assert.h"
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#include "periph/cpuid.h"
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#include "luid.h"
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#ifndef MAX
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#define MAX(a, b) (((a) > (b)) ? (a) : (b))
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#endif
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void __attribute__((weak)) luid_base(void *buf, size_t len)
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{
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memset(buf, LUID_BACKUP_SEED, len);
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#if CPUID_LEN
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uint8_t *out = (uint8_t *)buf;
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uint8_t cid[CPUID_LEN];
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cpuid_get(cid);
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for (size_t i = 0; i < MAX(len, CPUID_LEN); i++) {
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out[i % len] ^= cid[i % CPUID_LEN];
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}
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#endif
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}
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static uint8_t lastused;
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void luid_get(void *buf, size_t len)
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{
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luid_base(buf, len);
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((uint8_t *)buf)[0] ^= lastused++;
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}
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void luid_get_lb(void *buf, size_t len)
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{
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luid_base(buf, len);
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((uint8_t *)buf)[len - 1] ^= lastused++;
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}
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void luid_custom(void *buf, size_t len, int gen)
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{
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luid_base(buf, len);
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for (size_t i = 0; i < sizeof(gen); i++) {
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((uint8_t *)buf)[i % len] ^= ((gen >> (i * 8)) & 0xff);
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}
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}
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void luid_get_short(network_uint16_t *addr)
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{
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luid_base(addr, sizeof(*addr));
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addr->u8[1] ^= lastused++;
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/* https://tools.ietf.org/html/rfc4944#section-12 requires the first bit to
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* 0 for unicast addresses */
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addr->u8[0] &= 0x7F;
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}
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void luid_get_eui48(eui48_t *addr)
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{
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luid_base(addr, sizeof(*addr));
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addr->uint8[5] ^= lastused++;
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eui48_set_local(addr);
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eui48_clear_group(addr);
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}
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void luid_get_eui64(eui64_t *addr)
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{
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luid_base(addr, sizeof(*addr));
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addr->uint8[7] ^= lastused++;
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eui64_set_local(addr);
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eui64_clear_group(addr);
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}
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