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nimble/ll: Add helper to validate AA

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This commit is contained in:
Andrzej Kaczmarek
2023-01-27 19:55:18 +01:00
parent 5652310e74
commit 5b87eb0b62
2 changed files with 100 additions and 95 deletions
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nimble/controller/include/controller/ble_ll_utils.h
+1
View File
@@ -28,6 +28,7 @@
#define CLAMP(_n, _min, _max) (MAX(_min, MIN(_n, _max)))
#define IN_RANGE(_n, _min, _max) (((_n) >= (_min)) && ((_n) <= (_max)))
int ble_ll_utils_verify_aa(uint32_t aa);
uint32_t ble_ll_utils_calc_access_addr(void);
uint32_t ble_ll_utils_calc_seed_aa(void);
uint32_t ble_ll_utils_calc_big_aa(uint32_t seed_aa, uint32_t n);
nimble/controller/src/ble_ll_utils.c
+99 -95
View File
@@ -32,10 +32,9 @@ static const uint16_t g_ble_sca_ppm_tbl[8] = {
500, 250, 150, 100, 75, 50, 30, 20
};
uint32_t
ble_ll_utils_calc_access_addr(void)
int
ble_ll_utils_verify_aa(uint32_t aa)
{
uint32_t aa;
uint16_t aa_low;
uint16_t aa_high;
uint32_t temp;
@@ -47,100 +46,105 @@ ble_ll_utils_calc_access_addr(void)
uint8_t ones;
int tmp;
/* Calculate a random access address */
aa = 0;
while (1) {
/* Get two, 16-bit random numbers */
aa_low = ble_ll_rand() & 0xFFFF;
aa_high = ble_ll_rand() & 0xFFFF;
aa_low = aa & 0xffff;
aa_high = aa >> 16;
/* All four bytes cannot be equal */
if (aa_low == aa_high) {
continue;
}
/* Upper 6 bits must have 2 transitions */
tmp = (int16_t)aa_high >> 10;
if (__builtin_popcount(tmp ^ (tmp >> 1)) < 2) {
continue;
}
/* Cannot be access address or be 1 bit different */
aa = aa_high;
aa = (aa << 16) | aa_low;
bits_diff = 0;
temp = aa ^ BLE_ACCESS_ADDR_ADV;
for (mask = 0x00000001; mask != 0; mask <<= 1) {
if (mask & temp) {
++bits_diff;
if (bits_diff > 1) {
break;
}
}
}
if (bits_diff <= 1) {
continue;
}
/* Cannot have more than 24 transitions */
transitions = 0;
consecutive = 1;
ones = 0;
mask = 0x00000001;
while (mask < 0x80000000) {
prev_bit = aa & mask;
mask <<= 1;
if (mask & aa) {
if (prev_bit == 0) {
++transitions;
consecutive = 1;
} else {
++consecutive;
}
} else {
if (prev_bit == 0) {
++consecutive;
} else {
++transitions;
consecutive = 1;
}
}
if (prev_bit) {
ones++;
}
/* 8 lsb should have at least three 1 */
if (mask == 0x00000100 && ones < 3) {
break;
}
/* 16 lsb should have no more than 11 transitions */
if (mask == 0x00010000 && transitions > 11) {
break;
}
/* This is invalid! */
if (consecutive > 6) {
/* Make sure we always detect invalid sequence below */
mask = 0;
break;
}
}
/* Invalid sequence found */
if (mask != 0x80000000) {
continue;
}
/* Cannot be more than 24 transitions */
if (transitions > 24) {
continue;
}
/* We have a valid access address */
break;
/* All four bytes cannot be equal */
if (aa_low == aa_high) {
return 0;
}
/* Upper 6 bits must have 2 transitions */
tmp = (int16_t)aa_high >> 10;
if (__builtin_popcount(tmp ^ (tmp >> 1)) < 2) {
return 0;
}
/* Cannot be access address or be 1 bit different */
aa = aa_high;
aa = (aa << 16) | aa_low;
bits_diff = 0;
temp = aa ^ BLE_ACCESS_ADDR_ADV;
for (mask = 0x00000001; mask != 0; mask <<= 1) {
if (mask & temp) {
++bits_diff;
if (bits_diff > 1) {
break;
}
}
}
if (bits_diff <= 1) {
return 0;
}
/* Cannot have more than 24 transitions */
transitions = 0;
consecutive = 1;
ones = 0;
mask = 0x00000001;
while (mask < 0x80000000) {
prev_bit = aa & mask;
mask <<= 1;
if (mask & aa) {
if (prev_bit == 0) {
++transitions;
consecutive = 1;
} else {
++consecutive;
}
} else {
if (prev_bit == 0) {
++consecutive;
} else {
++transitions;
consecutive = 1;
}
}
if (prev_bit) {
ones++;
}
/* 8 lsb should have at least three 1 */
if (mask == 0x00000100 && ones < 3) {
break;
}
/* 16 lsb should have no more than 11 transitions */
if (mask == 0x00010000 && transitions > 11) {
break;
}
/* This is invalid! */
if (consecutive > 6) {
/* Make sure we always detect invalid sequence below */
mask = 0;
break;
}
}
/* Invalid sequence found */
if (mask != 0x80000000) {
return 0;
}
/* Cannot be more than 24 transitions */
if (transitions > 24) {
return 0;
}
return 1;
}
uint32_t
ble_ll_utils_calc_access_addr(void)
{
uint32_t aa;
do {
aa = ble_ll_rand();
} while (!ble_ll_utils_verify_aa(aa));
return aa;
}