smiVALUE structure (winsnmp.h)

Article
03/13/2023

[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 smiVALUE structure describes the value associated with a variable name in a variable binding entry.

The syntax member of the smiVALUE structure contains a WinSNMP data type that indicates the type of data in the value member. The value member of the structure is the union of all possible WinSNMP data types.

Syntax

typedef struct {
  smiUINT32 syntax;
  union {
    smiINT    sNumber;
    smiUINT32 uNumber;
    smiCNTR64 hNumber;
    smiOCTETS string;
    smiOID    oid;
    smiBYTE   empty;
  } value;
} smiVALUE, *smiLPVALUE;

Members

syntax

Type: smiUINT32

Specifies an unsigned long integer that indicates the syntax data type of the value member. This member can be only one of the types listed in the following table. For more information, see WinSNMP Data Types and RFC 1902, "Structure of Management Information for Version 2 of the Simple Network Management Protocol (SNMPv2)."

Syntax data type	Meaning
SNMP_SYNTAX_INT	Indicates a 32-bit signed integer variable.
SNMP_SYNTAX_OCTETS	Indicates an octet string variable that is binary or textual data.
SNMP_SYNTAX_NULL	Indicates a NULL value.
SNMP_SYNTAX_OID	Indicates an object identifier variable that is an assigned name with a maximum of 128 subidentifiers.
SNMP_SYNTAX_INT32	Indicates a 32-bit signed integer variable.
SNMP_SYNTAX_IPADDR	Indicates a 32-bit Internet address variable.
SNMP_SYNTAX_CNTR32	Indicates a counter variable that increases until it reaches a maximum value of (2^32) – 1.
SNMP_SYNTAX_GAUGE32	Indicates a gauge variable that is a non-negative integer that can increase or decrease, but never exceed a maximum value.
SNMP_SYNTAX_TIMETICKS	Indicates a counter variable that measures the time in hundredths of a second, until it reaches a maximum value of (2^32) – 1. It is a non-negative integer that is relative to a specific timer event.
SNMP_SYNTAX_OPAQUE	This type provides backward compatibility, and should not be used for new object types. It supports the capability to pass arbitrary Abstract Syntax Notation One (ASN.1) syntax.
SNMP_SYNTAX_CNTR64	Indicates a counter variable that increases until it reaches a maximum value of (2^64) – 1.
SNMP_SYNTAX_UINT32	Indicates a 32-bit unsigned integer variable.
SNMP_SYNTAX_NOSUCHOBJECT	Indicates that the agent does not support the object type that corresponds to the variable.
SNMP_SYNTAX_NOSUCHINSTANCE	Indicates that the object instance does not exist for the operation.
SNMP_SYNTAX_ENDOFMIBVIEW	Indicates the WinSNMP application is attempting to reference an object identifier that is beyond the end of the MIB tree that the agent supports.

The last three syntax types describe exception conditions under the SNMP version 2C (SNMPv2C) framework.

value

Specifies the union of all possible WinSNMP syntax data types, including the smiOID or smiOCTETS descriptor types.

sNumber

Type: smiINT Specifies a signed long integer value.

uNumber

Type: smiUINT32 Specifies a 32-bit unsigned long integer value.

hNumber

Type: smiCNTR64 Specifies a 64-bit unsigned integer value

string

Type: smiOCTETS Specifies a string.

oid

Type: smiOID Specifies an object identifier (OID).

empty

Type: smiBYTE Specifies an empty member.

value.sNumber

value.uNumber

value.hNumber

value.string

value.oid

value.empty

Remarks

A WinSNMP application must check the syntax member of an smiVALUE structure to correctly dereference the value member. The value member can contain a simple scalar value or a non-scalar value like an smiOCTETS or an smiOID descriptor structure.

If the syntax member indicates that the value member is an smiOCTETS or an smiOID descriptor structure, the WinSNMP application must determine whether to free the resources allocated for the structure. The Microsoft WinSNMP implementation allocates and deallocates memory for all output smiOCTETS and smiOID structures. The application must call the SnmpFreeDescriptor function to free the memory for the ptr member of these structures.

Because the WinSNMP application allocates memory for input descriptors with variable lengths, it must free that memory. For more information, see WinSNMP Data Management Concepts.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Header	winsnmp.h

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