Pointer to structure for addReadWriteStringHandler results in SNMP no such object

[dmarc1234]

I am trying to point the addReadWriteStringHandler() to a char array within a global structure to allow a GET and SET to be performed on it and I am having real problems getting to work.

I have tried creating a pointer to the structure and dereferencing the structure like this:

SNMPAgent * snmp;
snmp = new SNMPAgent("public", "private");

CONFIG_REG conf = new CONFIG_REG();
snmp->addReadWriteStringHandler(".1.3.6.1.4.1.38218.1.3.1.0", (char*) (*conf).sensor_name, 40, true);

But get a SNMP not such object reply in iReasoning MIB browser.

The snmp->addReadOnlyStaticStringHandler() works okay so I am at a loss as to why it will not work ?

[dmarc1234]

That line did come out right above, should be:

snmp->addReadWriteStringHandler(".1.3.6.1.4.1.38218.1.3.1.0", (char**)(*conf).sensor_name, 40, true);

[0neblock]

Hi @dmarc1234.
What is the type of (*conf).sensor_name?
If it is a char*, then you'll need to pass the reference of it to addReadWriteStringHandler().
For example: snmp->addReadWriteStringHandler(".1.3.6.1.4.1.38218.1.3.1.0", &(*conf).sensor_name, 40, true);
You shouldn't need to cast it to a char** unless it's not a char* originally.

Let me know if that helps!. Thanks.

[dmarc1234]

Thank you for your reply.

Yes, (*conf).sensor_name is a char within the CONFIG_REG structure.

I have tried:
snmp->addReadWriteStringHandler(".1.3.6.1.4.1.38218.1.3.1.0", &(*conf).sensor_name, 40, true);
but it will not compile, I need to cast to char** to make it compile, so:
snmp->addReadWriteStringHandler(".1.3.6.1.4.1.38218.1.3.1.0", (char**)&(*conf).client_name, 40, true);
which compiles but still results in a SNMP no such object error.

Also tried a different approach as follows:

CONFIG_REG *config = &configReg;
snmp->addReadWriteStringHandler(".1.3.6.1.4.1.38218.1.3.1.0", (char**)&config->sensor_name, 40, true);

which returns a blank string rather than the no object error.

Really not sure where to go next ?

[0neblock]

@dmarc1234 Can you show me the declaration of the CONFIG_REG type? What data type is sensor_name?

[dmarc1234]

This is how CONFIG_REG is defined:

// Structure to contain configuration information
typedef struct
{
	char		sensor_name[40];		// Sensor name
	char		sensor_location[40];	// Sensor location
} CONFIG_REG;

and then declared as a global in main.c :
CONFIG_REG configReg;

I then create a pointer to it using:
CONFIG_REG *config = &configReg;

[dmarc1234]

@0neblock did you see my message in relation to the structure, still struggling to get this to work.