static uint32_t prvIoTHubClientGetToken()

in source/azure_iot_hub_client.c [511:580]
58 lines of code
6 McCabe index (conditional complexity)

static uint32_t prvIoTHubClientGetToken( AzureIoTHubClient_t * pxAzureIoTHubClient,
                                         uint64_t ullExpiryTimeSecs,
                                         const uint8_t * ucKey,
                                         uint32_t ulKeyLen,
                                         uint8_t * pucSASBuffer,
                                         uint32_t ulSasBufferLen,
                                         uint32_t * pulSaSLength )
{
    uint8_t * pucHMACBuffer;
    az_span xSpan = az_span_create( pucSASBuffer, ( int32_t ) ulSasBufferLen );
    az_result xCoreResult;
    uint32_t ulSignatureLength;
    uint32_t ulBytesUsed;
    uint32_t ulBufferLeft;
    size_t xLength;

    xCoreResult = az_iot_hub_client_sas_get_signature( &( pxAzureIoTHubClient->_internal.xAzureIoTHubClientCore ),
                                                       ullExpiryTimeSecs, xSpan, &xSpan );

    if( az_result_failed( xCoreResult ) )
    {
        AZLogError( ( "AzureIoTHubClient failed to get signature: core error=0x%08x", ( uint16_t ) xCoreResult ) );
        return AzureIoT_TranslateCoreError( xCoreResult );
    }

    ulBytesUsed = ( uint32_t ) az_span_size( xSpan );
    ulBufferLeft = ulSasBufferLen - ulBytesUsed;

    if( ulBufferLeft < azureiothubHMACBufferLength )
    {
        AZLogError( ( "AzureIoTHubClient token generation failed with insufficient buffer size" ) );
        return eAzureIoTErrorOutOfMemory;
    }

    /* Calculate HMAC at the end of buffer, so we do less data movement when returning back to caller. */
    ulBufferLeft -= azureiothubHMACBufferLength;
    pucHMACBuffer = pucSASBuffer + ulSasBufferLen - azureiothubHMACBufferLength;

    if( AzureIoT_Base64HMACCalculate( pxAzureIoTHubClient->_internal.xHMACFunction,
                                      ucKey, ulKeyLen, pucSASBuffer, ulBytesUsed,
                                      pucSASBuffer + ulBytesUsed, ulBufferLeft,
                                      pucHMACBuffer, azureiothubHMACBufferLength,
                                      &ulSignatureLength ) != eAzureIoTSuccess )
    {
        AZLogError( ( "AzureIoTHubClient failed to encode HMAC hash" ) );
        return eAzureIoTErrorFailed;
    }

    if( ( ulSasBufferLen <= azureiothubHMACBufferLength ) )
    {
        AZLogError( ( "AzureIoTHubClient failed with insufficient buffer size" ) );
        return eAzureIoTErrorOutOfMemory;
    }

    xSpan = az_span_create( pucHMACBuffer, ( int32_t ) ulSignatureLength );
    xCoreResult = az_iot_hub_client_sas_get_password( &( pxAzureIoTHubClient->_internal.xAzureIoTHubClientCore ),
                                                      ullExpiryTimeSecs, xSpan, AZ_SPAN_EMPTY, ( char * ) pucSASBuffer,
                                                      ulSasBufferLen - azureiothubHMACBufferLength,
                                                      &xLength );

    if( az_result_failed( xCoreResult ) )
    {
        AZLogError( ( "AzureIoTHubClient failed to generate token: core error=0x%08x", ( uint16_t ) xCoreResult ) );
        return AzureIoT_TranslateCoreError( xCoreResult );
    }

    *pulSaSLength = ( uint32_t ) xLength;

    return eAzureIoTSuccess;
}