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28d1936fae
The CPU ID can have large parts that are identical between devices. To add some more entropy to the generated IDs, shuffle the bytes.
151 lines
3.1 KiB
C
151 lines
3.1 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 = buf;
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uint8_t cid[CPUID_LEN];
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uint8_t sum = 0;
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cpuid_get(cid);
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/* CPU ID is XORed with LUID_BACKUP_SEED.
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* Then Fisher–Yates shuffle is performed to mix
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* the bytes, as often large continuous chunks of
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* CPU ID are equal on machines with the same CPU.
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*/
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for (size_t i = 0; i < MAX(len, CPUID_LEN); i++) {
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uint8_t tmp, j, k;
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j = i % len;
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k = i % CPUID_LEN;
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/* xor with CPU ID */
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out[j] ^= cid[k];
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/* get 'random' position */
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sum += out[j];
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k = sum % (j + 1);
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/* shuffle bytes */
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tmp = out[j];
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out[j] = out[k];
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out[k] = tmp;
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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_netdev_get_eui48(const netdev_t *netdev, eui48_t *addr)
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{
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luid_base(addr, sizeof(*addr));
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#ifdef MODULE_NETDEV_REGISTER
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addr->uint8[4] ^= netdev->type;
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addr->uint8[5] ^= netdev->index;
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#else
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/* we should only get here with gnrc_netif_single */
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(void)netdev;
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#endif
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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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void luid_netdev_get_eui64(const netdev_t *netdev, eui64_t *addr)
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{
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luid_base(addr, sizeof(*addr));
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#ifdef MODULE_NETDEV_REGISTER
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addr->uint8[6] ^= netdev->type;
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addr->uint8[7] ^= netdev->index;
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#else
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/* we should only get here with gnrc_netif_single */
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(void)netdev;
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#endif
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eui64_set_local(addr);
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eui64_clear_group(addr);
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}
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