为什么我的设备从 Azure IoTHub 接收 Azure 直接方法有效负载，最后附加了垃圾？

Question

我正在我的设备（raspi）上运行一个直接方法处理程序模块，该模块在调用熟悉的直接方法调用时记录有效负载。但是当我打印有效负载时，它的末尾附加了垃圾数据。 设备上的模块使用 Azure C SDK 和基于 WebSockets 的 MQTT。

我尝试调用以下直接方法调用：

az iot hub invoke-module-method --device-id raspi --module-id raspiNayax --method-name start-transaction --hub-name dcfcdev --method-payload '{\"deviceId\":\"pedestal1\",\"type\":\"start-transaction\",\"timestamp\":\"2024-06-07T04:13:21.9172154Z\",\"sequenceId\":\"1ABC\",\"parameters\":[{\"name\":\"connectorOcppNumber\",\"value\":5},{\"name\":\"productCode\",\"value\":2},{\"name\":\"productPrice\",\"value\":"test1"}]}'

模块在设备上打印的内容：

Method name: start-transaction, Payload: {"deviceId":"pedestal1","type":"start-transaction","timestamp":"2024-06-07T04:13:21.9172154Z","sequenceId":"1ABC","parameters":[{"name":"connectorOcppNumber","value":5},{"name":"productCode","value":2},{"name":"productPrice","value":"test1"}]}**767733**

这就是我创建在设备上运行的直接方法处理程序的方法：

int DirectMethodCb(const char* method_name, const unsigned char* payload, size_t size, unsigned char** response, size_t* resp_size, void* userContextCallback)
{   
char deviceMethodResponse[MAX_RESPONSE_LENGTH];  
int responseCode  = 400; 

    printf("+++++++++++++ Direct method call received +++++++++++++\n");
__log_ts("Azure Direct Method Received \n Method name: %s, Payload: %s\n", method_name, payload);  

if(strcmp("is-ready", method_name) == 0){
    __log_ts("Direct method: is-ready\n");

    responseCode = payload_parser(payload, IS_READY); 
    strcpy(deviceMethodResponse, "{}");

}else if(strcmp("is-available", method_name) == 0){
    __log_ts("Direct method: is-available\n");
    
    responseCode = payload_parser(payload, IS_AVAILABLE); 
    responseCode = get_current_session(IS_AVAILABLE); 

    strcpy(deviceMethodResponse, "{}");

}else if(strcmp("start-transaction", method_name) == 0){
    __log_ts("Direct method: start-transaction\n");

    responseCode = start_transaction_handler(payload); 
    strcpy(deviceMethodResponse, "{}");

}else if(strcmp("close-transaction", method_name) == 0){
    __log_ts("Direct method: close-transaction\n");

    // responseCode = payload_parser(payload, CLOSE_TRANSACTION); 
    responseCode = close_cancel_session_handler(payload, CLOSE_TRANSACTION);
    strcpy(deviceMethodResponse, "{}");

}else if(strcmp("cancel-transaction", method_name) == 0){
    __log_ts("Direct method: cancel-transaction\n");

    // responseCode = cancel_session_handler(payload); 
    responseCode = close_cancel_session_handler(payload, CANCEL_TRANSACTION); 
    strcpy(deviceMethodResponse, "{}");

}else{
    responseCode = 700; 
    strcpy(deviceMethodResponse, "{}");
}

*resp_size = strlen(deviceMethodResponse);
*response = malloc(*resp_size + 1); // Allocate an extra byte for the null-terminator
strncpy((char *)*response, deviceMethodResponse, *resp_size); // Use strncpy to copy the string
(*response)[*resp_size] = '\0';
__log_ts("Azure Direct Method to method call:%s\n Response Code: %d, Response Payload: %s\n", method_name, responseCode, deviceMethodResponse); 

fflush(NULL);
return responseCode;
}

void *init_az_service(void *arg) {
IOTHUB_MODULE_CLIENT_LL_HANDLE iotHubModuleClientHandle = NULL;
int retval = 1;

do{
    printf("\n\n=======================\n");

    fflush(NULL);

    srand((unsigned int)time(NULL));
    
    // Ensuring platform is initialized. 
    if (0 != IoTHub_Init())
    {

        // printf("Failed to initialize the platform.");
        __log_ts("Failed to initialize the platform.\n");

        break;
    }

    // |** Establish MQTT protocol. **| 
    iotHubModuleClientHandle = IoTHubModuleClient_LL_CreateFromEnvironment(MQTT_Protocol);
    if (NULL == iotHubModuleClientHandle)
    {
        // printf("IoTHubModuleClient_LL_CreateFromEnvironment failed");
        __log_ts("IoTHubModuleClient_LL_CreateFromEnvironment failed\n");
        break;
    }

    // Setting up the Direct Method Callback function. 
    IOTHUB_CLIENT_RESULT result = IoTHubModuleClient_LL_SetModuleMethodCallback(iotHubModuleClientHandle, DirectMethodCb, iotHubModuleClientHandle);
    if (IOTHUB_CLIENT_OK != result)
    {
        // printf("IoTHubModuleClient_SetModuleMethodCallback failed: %d", result);
        __log_ts("IoTHubModuleClient_SetModuleMethodCallback failed: %d\n", result);
        break;
    }


while (true)
{
    IoTHubModuleClient_LL_DoWork(iotHubModuleClientHandle);
    ThreadAPI_Sleep(100);
}

}while(false); 

// Destroy iotHubModuleClientHandle if function errored out. 
if (NULL != iotHubModuleClientHandle)
{
    IoTHubModuleClient_LL_Destroy(iotHubModuleClientHandle);
}
IoTHub_Deinit();

return retval;

}

Answer 1

这可能是 Azure 中反复出现的问题。 您可以尝试探索其他物联网平台，例如www.iotellect.com