SnmpCreatePdu function (winsnmp.h)

Article
10/13/2021

[SNMP is available for use in the operating systems specified in the Requirements section. It may be altered or unavailable in subsequent versions. Instead, use Windows Remote Management, which is the Microsoft implementation of WS-Man.]

The WinSNMP SnmpCreatePdu function creates and initializes an SNMP protocol data unit (PDU).

Syntax

HSNMP_PDU SNMPAPI_CALL SnmpCreatePdu(
  [in] HSNMP_SESSION session,
  [in] smiINT        PDU_type,
  [in] smiINT32      request_id,
  [in] smiINT        error_status,
  [in] smiINT        error_index,
  [in] HSNMP_VBL     varbindlist
);

Parameters

[in] session

Handle to the WinSNMP session.

[in] PDU_type

Specifies a PDU type that identifies the SNMP operation. This parameter can be NULL, or it can be one of the following values. If this parameter is NULL, the Microsoft WinSNMP implementation supplies the default PDU type SNMP_PDU_GETNEXT. The only type of trap PDU you can create with a call to the SnmpCreatePdu function is an SNMPv2C trap PDU.

Value	Meaning
SNMP_PDU_GET	Search and retrieve a value from a specified SNMP variable.
SNMP_PDU_GETNEXT	Search and retrieve the value of an SNMP variable without knowing the exact name of the variable.
SNMP_PDU_RESPONSE	Reply to an SNMP_PDU_GET or an SNMP_PDU_GETNEXT request.
SNMP_PDU_SET	Store a value in a specified SNMP variable.
SNMP_PDU_GETBULK	Search and retrieve multiple values with a single request.
SNMP_PDU_TRAP	Alerts the management system to an event under SNMPv2C.

[in] request_id

Specifies a unique numeric value that the WinSNMP application supplies to identify the PDU. If this parameter is NULL, the implementation assigns a value.

[in] error_status

If the PDU_type parameter is equal to SNMP_PDU_GETBULK, this parameter specifies a value for the non_repeaters field of the PDU. For other PDU types, this parameter specifies a value for the error_status field of the PDU. This parameter can be NULL.

[in] error_index

If the PDU_type parameter is equal to SNMP_PDU_GETBULK, this parameter specifies a value for the max_repetitions field of the PDU. For other PDU types, this parameter specifies a value for the error_index field of the PDU. This parameter can be NULL.

[in] varbindlist

Handle to a structure that represents an SNMP variable bindings list. This parameter can be NULL.

Return value

If the function succeeds, the return value is the handle to a new SNMP PDU.

If the function fails, the return value is SNMPAPI_FAILURE. To get extended error information, call SnmpGetLastError. The SnmpGetLastError function can return one of the following errors.

Return code	Description
SNMPAPI_NOT_INITIALIZED	The SnmpStartup function did not complete successfully.
SNMPAPI_ALLOC_ERROR	An error occurred during memory allocation.
SNMPAPI_SESSION_INVALID	The session handle is invalid.
SNMPAPI_PDU_INVALID	The PDU type is invalid.
SNMPAPI_VBL_INVALID	The variable bindings list is invalid.
SNMPAPI_OTHER_ERROR	An unknown or undefined error occurred.

Remarks

A WinSNMP application must create a PDU before it calls the SnmpSendMsg or the SnmpEncodeMsg functions.

All of the parameters of the SnmpCreatePdu function are required. However, all parameters, except the session parameter, can be NULL. In this instance, the new PDU has the following default values.

Field	Contents
PDU_type	SNMP_PDU_GETNEXT
request_id	The implementation generates a numeric value.
error_status	SNMP_ERROR_NOERROR
error_index	0
varbindlist	NULL

The application must call the SnmpFreePdu function to release the resources that the SnmpCreatePdu function allocates for the new PDU.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	winsnmp.h
Library	Wsnmp32.lib
DLL	Wsnmp32.dll