Platform SDK: Network Management

SnmpDecodeMsg

The WinSNMP SnmpDecodeMsg function decodes an encoded SNMP message into its components. This function performs the opposite action of the WinSNMP SnmpEncodeMsg function.

SNMPAPI_STATUS SnmpDecodeMsg(
  HSNMP_SESSION session,     // handle to the WinSNMP session 
  LPHSNMP_ENTITY srcEntity,  // handle to the source entity 
  LPHSNMP_ENTITY dstEntity,  // handle to the target entity 
  LPHSNMP_CONTEXT context,   // handle to the context 
  LPHSNMP_PDU pdu,           // handle to the PDU 
  smiLPCOCTETS msgBufDesc    // pointer to the message buffer 
);

Parameters

session: [in] Handle to the WinSNMP session. This parameter is required. For additional information, see the following Remarks section.
srcEntity: [out] Pointer to a variable that receives a handle to the source management entity. For more information, see the following Remarks section.
dstEntity: [out] Pointer to a variable that receives a handle to the target management entity. For more information, see the following Remarks section.
context: [out] Pointer to a variable that receives a handle to the context (a set of managed object resources) that the target management entity controls.
pdu: [out] Pointer to a variable that receives a handle to the SNMP protocol data unit (PDU).
msgBufDesc: [in] Pointer to an smiOCTETS structure that contains the SNMP message to decode into its components. The len member of the structure specifies the maximum number of bytes to process; the ptr member points to the encoded SNMP message.

Return Values

If the function succeeds, the return value is the number of decoded bytes. This value can be equal to, or less than, the len member of the smiOCTETS structure pointed to by the msgBufDesc parameter.

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.

Error 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 parameter is invalid.
SNMPAPI_ENTITY_INVALID	One or both of the entity parameters is invalid.
SNMPAPI_CONTEXT_INVALID	The context parameter is invalid.
SNMPAPI_PDU_INVALID	The pdu parameter is invalid.
SNMPAPI_OUTPUT_TRUNCATED	The output buffer length is insufficient. No output parameters were created.
SNMPAPI_MESSAGE_INVALID	The SNMP message format in the buffer indicated by the msgBufDesc parameter is invalid. No output parameters were created.
SNMPAPI_OTHER_ERROR	An unknown or undefined error occurred.

Remarks

The Microsoft WinSNMP implementation returns a value of zero in the srcEntity and the dstEntity parameters when an application submits an SNMPv1 or an SNMPv2C message to the SnmpDecodeMsg function. This is because the message format does not include the address information necessary to create WinSNMP entity resources.

The Microsoft WinSNMP implementation allocates resources to the WinSNMP application as a result of a successful call to the SnmpDecodeMsg function. It is recommended that the WinSNMP application free individual resources with the WinSNMP function that corresponds to the resource. For additional information, see Freeing WinSNMP Descriptors and WinSNMP Data Management Concepts.

Requirements

  Windows NT/2000: Requires Windows 2000.
  Windows 95/98: Unsupported.
  Header: Declared in Winsnmp.h.
  Library: Use Wsnmp32.lib.

SnmpDecodeMsg

Parameters

Return Values

Remarks

Requirements

See Also