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[ESP32] Handle NVS key with length > 15 #18604

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merged 3 commits into from
May 23, 2022
Merged

[ESP32] Handle NVS key with length > 15 #18604

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8116a0b
[ESP32] Handle NVS key with length > 15
shubhamdp May 19, 2022
2a8689a
Restyled by clang-format
restyled-commits May 19, 2022
0c3ff66
Using helper API BytesToHex() and now function returns bool value
shubhamdp May 23, 2022
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37 changes: 37 additions & 0 deletions src/platform/ESP32/KeyValueStoreManagerImpl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -29,12 +29,39 @@

#include "nvs.h"
#include "nvs_flash.h"
#include <crypto/CHIPCryptoPAL.h>
#include <lib/support/CodeUtils.h>

namespace chip {
namespace DeviceLayer {
namespace PersistedStorage {

namespace {
// Implementation Note: esp-idf nvs implementation cannot handle key length > 15,
// Below implementation tries to handle that case by hashing the key
// If key length is > 15 then take the SHA1 of the key and convert the first 8 bytes to hex string.
// Not sure how likely we would run into a conflict as we are only using 8 bytes out of 20

CHIP_ERROR HashIfLongKey(const char * key, char * keyHash)
{
VerifyOrReturnError(strlen(key) > (NVS_KEY_NAME_MAX_SIZE - 1), CHIP_ERROR_INCORRECT_STATE);
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uint8_t hashBuffer[chip::Crypto::kSHA1_Hash_Length];
ReturnErrorOnFailure(chip::Crypto::Hash_SHA1((const uint8_t *) key, strlen(key), hashBuffer));
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int i = 0, j = 0;
while (i < NVS_KEY_NAME_MAX_SIZE)
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{
sprintf(keyHash + i, "%02x", hashBuffer[j]);
i += 2;
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j += 1;
}
keyHash[NVS_KEY_NAME_MAX_SIZE - 1] = 0;
ChipLogDetail(DeviceLayer, "Using hash:%s for nvs key:%s", keyHash, key);
return CHIP_NO_ERROR;
}
} // namespace

KeyValueStoreManagerImpl KeyValueStoreManagerImpl::sInstance;

CHIP_ERROR KeyValueStoreManagerImpl::_Get(const char * key, void * value, size_t value_size, size_t * read_bytes_size,
Expand All @@ -48,6 +75,10 @@ CHIP_ERROR KeyValueStoreManagerImpl::_Get(const char * key, void * value, size_t

Internal::ScopedNvsHandle handle;
ReturnErrorOnFailure(handle.Open(kNamespace, NVS_READONLY));

char keyHash[NVS_KEY_NAME_MAX_SIZE];
VerifyOrdo(HashIfLongKey(key, keyHash) != CHIP_NO_ERROR, key = keyHash);

ReturnMappedErrorOnFailure(nvs_get_blob(handle, key, value, &value_size));

if (read_bytes_size)
Expand All @@ -65,6 +96,9 @@ CHIP_ERROR KeyValueStoreManagerImpl::_Put(const char * key, const void * value,
Internal::ScopedNvsHandle handle;
ReturnErrorOnFailure(handle.Open(kNamespace, NVS_READWRITE));

char keyHash[NVS_KEY_NAME_MAX_SIZE];
VerifyOrdo(HashIfLongKey(key, keyHash) != CHIP_NO_ERROR, key = keyHash);

ReturnMappedErrorOnFailure(nvs_set_blob(handle, key, value, value_size));

// Commit the value to the persistent store.
Expand All @@ -79,6 +113,9 @@ CHIP_ERROR KeyValueStoreManagerImpl::_Delete(const char * key)

ReturnErrorOnFailure(handle.Open(kNamespace, NVS_READWRITE));

char keyHash[NVS_KEY_NAME_MAX_SIZE];
VerifyOrdo(HashIfLongKey(key, keyHash) != CHIP_NO_ERROR, key = keyHash);

ReturnMappedErrorOnFailure(nvs_erase_key(handle, key));

// Commit the value to the persistent store.
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