src/app/util/attribute-table.cpp

/**
 *
 *    Copyright (c) 2020 Project CHIP Authors
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
#include <app/util/attribute-table.h>

#include <app/util/attribute-table-detail.h>

#include <app/util/attribute-storage-detail.h>
#include <app/util/attribute-storage.h>
#include <app/util/config.h>
#include <app/util/ember-strings.h>
#include <app/util/generic-callbacks.h>
#include <app/util/odd-sized-integers.h>
#include <lib/core/CHIPConfig.h>

#include <app/reporting/reporting.h>
#include <protocols/interaction_model/Constants.h>

#if (CHIP_CONFIG_BIG_ENDIAN_TARGET)
#define EM_BIG_ENDIAN true
#else
#define EM_BIG_ENDIAN false
#endif

using chip::Protocols::InteractionModel::Status;

using namespace chip;
using namespace chip::app;

namespace {
// Zigbee spec says types between signed 8 bit and signed 64 bit
bool emberAfIsTypeSigned(EmberAfAttributeType dataType)
{
    return (dataType >= ZCL_INT8S_ATTRIBUTE_TYPE && dataType <= ZCL_INT64S_ATTRIBUTE_TYPE);
}

/**
 * @brief Simple integer comparison function.
 * Compares two values of a known length as integers.
 * Signed integer comparison are supported for numbers with length of
 * 4 (bytes) or less.
 * The integers are in native endianness.
 *
 * @return -1, if val1 is smaller
 *          0, if they are the same or if two negative numbers with length
 *          greater than 4 is being compared
 *          1, if val2 is smaller.
 *
 * You can pass in val1 as NULL, which will assume that it is
 * pointing to an array of all zeroes. This is used so that
 * default value of NULL is treated as all zeroes.
 */
int8_t emberAfCompareValues(const uint8_t * val1, const uint8_t * val2, uint16_t len, bool signedNumber)
{
    if (len == 0)
    {
        // no length means nothing to compare.  Shouldn't even happen, since len is sizeof(some-integer-type).
        return 0;
    }

    if (signedNumber)
    { // signed number comparison
        if (len <= 4)
        { // only number with 32-bits or less is supported
            int32_t accum1 = 0x0;
            int32_t accum2 = 0x0;
            int32_t all1s  = -1;

            for (uint16_t i = 0; i < len; i++)
            {
                uint8_t j = (val1 == nullptr ? 0 : (EM_BIG_ENDIAN ? val1[i] : val1[(len - 1) - i]));
                accum1 |= j << (8 * (len - 1 - i));

                uint8_t k = (EM_BIG_ENDIAN ? val2[i] : val2[(len - 1) - i]);
                accum2 |= k << (8 * (len - 1 - i));
            }

            // sign extending, no need for 32-bits numbers
            if (len < 4)
            {
                if ((accum1 & (1 << (8 * len - 1))) != 0)
                { // check sign
                    accum1 |= all1s - ((1 << (len * 8)) - 1);
                }
                if ((accum2 & (1 << (8 * len - 1))) != 0)
                { // check sign
                    accum2 |= all1s - ((1 << (len * 8)) - 1);
                }
            }

            if (accum1 > accum2)
            {
                return 1;
            }
            if (accum1 < accum2)
            {
                return -1;
            }

            return 0;
        }

        // not supported
        return 0;
    }

    // regular unsigned number comparison
    for (uint16_t i = 0; i < len; i++)
    {
        uint8_t j = (val1 == nullptr ? 0 : (EM_BIG_ENDIAN ? val1[i] : val1[(len - 1) - i]));
        uint8_t k = (EM_BIG_ENDIAN ? val2[i] : val2[(len - 1) - i]);

        if (j > k)
        {
            return 1;
        }
        if (k > j)
        {
            return -1;
        }
    }
    return 0;
}

/**
 * @brief write an attribute, performing all the checks.
 *
 * This function will attempt to write the attribute value from
 * the provided pointer. This function will only check that the
 * attribute exists. If it does it will write the value into
 * the attribute table for the given attribute.
 *
 * This function will not check to see if the attribute is
 * writable since the read only / writable characteristic
 * of an attribute only pertains to external devices writing
 * over the air. Because this function is being called locally
 * it assumes that the device knows what it is doing and has permission
 * to perform the given operation.
 *
 * if true is passed in for overrideReadOnlyAndDataType then the data type is
 * not checked and the read-only flag is ignored. This mode is meant for
 * testing or setting the initial value of the attribute on the device.
 *
 * this returns:
 * - Status::UnsupportedEndpoint: if endpoint isn't supported by the device.
 * - Status::UnsupportedCluster: if cluster isn't supported on the endpoint.
 * - Status::UnsupportedAttribute: if attribute isn't supported in the cluster.
 * - Status::InvalidDataType: if the data type passed in doesnt match the type
 *           stored in the attribute table
 * - Status::UnsupportedWrite: if the attribute isnt writable
 * - Status::ConstraintError: if the value is set out of the allowable range for
 *           the attribute
 * - Status::Success: if the attribute was found and successfully written
 */
Status emAfWriteAttribute(EndpointId endpoint, ClusterId cluster, AttributeId attributeID, uint8_t * data,
                          EmberAfAttributeType dataType, bool overrideReadOnlyAndDataType, MarkAttributeDirty markDirty);
} // anonymous namespace

Status emAfWriteAttributeExternal(EndpointId endpoint, ClusterId cluster, AttributeId attributeID, uint8_t * dataPtr,
                                  EmberAfAttributeType dataType)
{
    return emAfWriteAttribute(endpoint, cluster, attributeID, dataPtr, dataType, false /* override read-only */,
                              MarkAttributeDirty::kIfChanged);
}

Status emberAfWriteAttribute(EndpointId endpoint, ClusterId cluster, AttributeId attributeID, uint8_t * dataPtr,
                             EmberAfAttributeType dataType)
{
    return emAfWriteAttribute(endpoint, cluster, attributeID, dataPtr, dataType, true /* override read-only */,
                              MarkAttributeDirty::kIfChanged);
}

Status emberAfWriteAttribute(EndpointId endpoint, ClusterId cluster, AttributeId attributeID, uint8_t * dataPtr,
                             EmberAfAttributeType dataType, MarkAttributeDirty markDirty)
{
    return emAfWriteAttribute(endpoint, cluster, attributeID, dataPtr, dataType, true /* override read-only */, markDirty);
}

//------------------------------------------------------------------------------
// Internal Functions

// Helper for determining whether a value is a null value.
template <typename T>
static bool IsNullValue(const uint8_t * data)
{
    using Traits = app::NumericAttributeTraits<T>;
    // We don't know how data is aligned, so safely copy it over to the relevant
    // StorageType value.
    typename Traits::StorageType val;
    memcpy(&val, data, sizeof(val));
    return Traits::IsNullValue(val);
}

static bool IsNullValue(const uint8_t * data, uint16_t dataLen, bool isAttributeSigned)
{
    if (dataLen > 4)
    {
        // We don't support this, just like emberAfCompareValues does not.
        return false;
    }

    switch (dataLen)
    {
    case 1: {
        if (isAttributeSigned)
        {
            return IsNullValue<int8_t>(data);
        }
        return IsNullValue<uint8_t>(data);
    }
    case 2: {
        if (isAttributeSigned)
        {
            return IsNullValue<int16_t>(data);
        }
        return IsNullValue<uint16_t>(data);
    }
    case 3: {
        if (isAttributeSigned)
        {
            return IsNullValue<app::OddSizedInteger<3, true>>(data);
        }
        return IsNullValue<app::OddSizedInteger<3, false>>(data);
    }
    case 4: {
        if (isAttributeSigned)
        {
            return IsNullValue<int32_t>(data);
        }
        return IsNullValue<uint32_t>(data);
    }
    }

    // Not reached.
    return false;
}

namespace {

/**
 * Helper function to determine whether the attribute value for the given
 * attribute is changing.  On success, the isChanging outparam will be set to
 * whether the value is changing.
 */
Status AttributeValueIsChanging(EndpointId endpoint, ClusterId cluster, AttributeId attributeID,
                                const EmberAfAttributeMetadata * metadata, uint8_t * newValueData, bool * isChanging)
{
    EmberAfAttributeType attributeType = metadata->attributeType;

    // We don't know how to size our buffer for strings in general, but if the
    // string happens to fit into our fixed-size buffer, great.
    size_t valueSize               = metadata->size;
    constexpr size_t kMaxValueSize = 16; // ipv6adr
    if (valueSize > kMaxValueSize)
    {
        if (emberAfIsStringAttributeType(attributeType) || emberAfIsLongStringAttributeType(attributeType))
        {
            // It's a string that may not fit in our buffer.  Just claim it's
            // changing, since we have no way to tell.
            *isChanging = true;
            return Status::Success;
        }

        // Very much unexpected
        ChipLogError(Zcl, "Attribute type %d has too-large size %u", attributeType, static_cast<unsigned>(valueSize));
        return Status::ConstraintError;
    }

    uint8_t oldValueBuffer[kMaxValueSize];
    // Cast to uint16_t is safe, because we checked valueSize <= kMaxValueSize above.
    if (emberAfReadAttribute(endpoint, cluster, attributeID, oldValueBuffer, static_cast<uint16_t>(valueSize)) != Status::Success)
    {
        // We failed to read the old value, so flag the value as changing to be safe.
        *isChanging = true;
        return Status::Success;
    }

    if (emberAfIsStringAttributeType(attributeType))
    {
        size_t oldLength = emberAfStringLength(oldValueBuffer);
        size_t newLength = emberAfStringLength(newValueData);
        // The first byte of the buffer is the string length, and
        // oldLength/newLength refer to the number of bytes after that.  We want
        // to include that first byte in our comparison, because null and empty
        // string have different values there but both return 0 from
        // emberAfStringLength.
        *isChanging = (oldLength != newLength) || (memcmp(oldValueBuffer, newValueData, oldLength + 1) != 0);
    }
    else if (emberAfIsLongStringAttributeType(attributeType))
    {
        size_t oldLength = emberAfLongStringLength(oldValueBuffer);
        size_t newLength = emberAfLongStringLength(newValueData);
        // The first two bytes of the buffer are the string length, and
        // oldLength/newLength refer to the number of bytes after that.  We want
        // to include those first two bytes in our comparison, because null and
        // empty string have different values there but both return 0 from
        // emberAfLongStringLength.
        *isChanging = (oldLength != newLength) || (memcmp(oldValueBuffer, newValueData, oldLength + 2) != 0);
    }
    else
    {
        *isChanging = (memcmp(newValueData, oldValueBuffer, valueSize) != 0);
    }

    return Status::Success;
}

Status emAfWriteAttribute(EndpointId endpoint, ClusterId cluster, AttributeId attributeID, uint8_t * data,
                          EmberAfAttributeType dataType, bool overrideReadOnlyAndDataType, MarkAttributeDirty markDirty)
{
    const EmberAfAttributeMetadata * metadata = nullptr;
    EmberAfAttributeSearchRecord record;
    record.endpoint    = endpoint;
    record.clusterId   = cluster;
    record.attributeId = attributeID;
    Status status      = emAfReadOrWriteAttribute(&record, &metadata,
                                                  nullptr, // buffer
                                                  0,       // buffer size
                                                  false);  // write?

    // if we dont support that attribute
    if (metadata == nullptr)
    {
        ChipLogProgress(Zcl, "%p ep %x clus " ChipLogFormatMEI " attr " ChipLogFormatMEI " not supported", "WRITE ERR: ", endpoint,
                        ChipLogValueMEI(cluster), ChipLogValueMEI(attributeID));
        return status;
    }

    // if the data type specified by the caller is incorrect
    if (!(overrideReadOnlyAndDataType))
    {
        if (dataType != metadata->attributeType)
        {
            ChipLogProgress(Zcl, "%p invalid data type", "WRITE ERR: ");
            return Status::InvalidDataType;
        }

        if (metadata->IsReadOnly())
        {
            ChipLogProgress(Zcl, "%p attr not writable", "WRITE ERR: ");
            return Status::UnsupportedWrite;
        }
    }

    // if the value the attribute is being set to is out of range
    // return Status::ConstraintError
    if ((metadata->mask & ATTRIBUTE_MASK_MIN_MAX) != 0U)
    {
        EmberAfDefaultAttributeValue minv = metadata->defaultValue.ptrToMinMaxValue->minValue;
        EmberAfDefaultAttributeValue maxv = metadata->defaultValue.ptrToMinMaxValue->maxValue;
        uint16_t dataLen                  = emberAfAttributeSize(metadata);
        const uint8_t * minBytes;
        const uint8_t * maxBytes;
        if (dataLen <= 2)
        {
            static_assert(sizeof(minv.defaultValue) == 2, "if statement relies on size of minv.defaultValue being 2");
            static_assert(sizeof(maxv.defaultValue) == 2, "if statement relies on size of maxv.defaultValue being 2");
            minBytes = reinterpret_cast<const uint8_t *>(&(minv.defaultValue));
            maxBytes = reinterpret_cast<const uint8_t *>(&(maxv.defaultValue));
// On big endian cpu with length 1 only the second byte counts
#if (CHIP_CONFIG_BIG_ENDIAN_TARGET)
            if (dataLen == 1)
            {
                minBytes++;
                maxBytes++;
            }
#endif // CHIP_CONFIG_BIG_ENDIAN_TARGET
        }
        else
        {
            minBytes = minv.ptrToDefaultValue;
            maxBytes = maxv.ptrToDefaultValue;
        }

        bool isAttributeSigned = emberAfIsTypeSigned(metadata->attributeType);
        bool isOutOfRange      = emberAfCompareValues(minBytes, data, dataLen, isAttributeSigned) == 1 ||
            emberAfCompareValues(maxBytes, data, dataLen, isAttributeSigned) == -1;

        if (isOutOfRange &&
            // null value is always in-range for a nullable attribute.
            (!metadata->IsNullable() || !IsNullValue(data, dataLen, isAttributeSigned)))
        {
            return Status::ConstraintError;
        }
    }

    // Check whether anything is actually changing, before we do any work here.
    bool valueChanging;
    Status imStatus = AttributeValueIsChanging(endpoint, cluster, attributeID, metadata, data, &valueChanging);
    if (imStatus != Status::Success)
    {
        return imStatus;
    }

    if (!valueChanging)
    {
        // Just do nothing.
        return Status::Success;
    }

    const app::ConcreteAttributePath attributePath(endpoint, cluster, attributeID);

    // Pre write attribute callback for all attribute changes,
    // regardless of cluster.
    imStatus = MatterPreAttributeChangeCallback(attributePath, dataType, emberAfAttributeSize(metadata), data);
    if (imStatus != Protocols::InteractionModel::Status::Success)
    {
        return imStatus;
    }

    // Pre-write attribute callback specific
    // to the cluster that the attribute lives in.
    status = emAfClusterPreAttributeChangedCallback(attributePath, dataType, emberAfAttributeSize(metadata), data);

    // Ignore the following write operation and return success
    if (status == Status::WriteIgnored)
    {
        return Status::Success;
    }

    if (status != Status::Success)
    {
        return status;
    }

    // write the attribute
    status = emAfReadOrWriteAttribute(&record,
                                      nullptr, // metadata
                                      data,
                                      0,     // buffer size - unused
                                      true); // write?

    if (status != Status::Success)
    {
        return status;
    }

    // Save the attribute to persistent storage if needed
    // The callee will weed out attributes that do not need to be stored.
    emAfSaveAttributeToStorageIfNeeded(data, endpoint, cluster, metadata);

    if (markDirty != MarkAttributeDirty::kNo)
    {
        MatterReportingAttributeChangeCallback(endpoint, cluster, attributeID);
    }

    // Post write attribute callback for all attributes changes, regardless
    // of cluster.
    MatterPostAttributeChangeCallback(attributePath, dataType, emberAfAttributeSize(metadata), data);

    // Post-write attribute callback specific
    // to the cluster that the attribute lives in.
    emAfClusterAttributeChangedCallback(attributePath);

    return Status::Success;
}

} // anonymous namespace

Status emberAfReadAttribute(EndpointId endpoint, ClusterId cluster, AttributeId attributeID, uint8_t * dataPtr, uint16_t readLength)
{
    const EmberAfAttributeMetadata * metadata = nullptr;
    EmberAfAttributeSearchRecord record;
    Status status;
    record.endpoint    = endpoint;
    record.clusterId   = cluster;
    record.attributeId = attributeID;
    status             = emAfReadOrWriteAttribute(&record, &metadata, dataPtr, readLength,
                                                  false); // write?

    // failed, print debug info
    if (status == Status::ResourceExhausted)
    {
        ChipLogProgress(Zcl, "READ: attribute size too large for caller");
    }

    return status;
}