snmp_pdu_add_variable, snmp_varlist_add_variable, snmp_add_null_var, snmp_clone_varbind,
Contents
Description
The functions dealing with variable bindings fall into four groups - dealing with the creation, setting
of values, output and deletion of varbinds.
Creationsnmp_pdu_add_variable will create a new varbind structure, initialised with the name ( objid, objidlen ),
syntax ( type ) and value ( value,len ) provided. This varbind is then added to the end of the
varbind list in the given PDU.
snmp_varlist_add_variable is similar, but appends the new varbind to the end of the varbind list
provided. When adding the first varbind to an empty list, simply pass the address of the head of the
list:
netsnmp_variable_list *vl = NULL;
snmp_varlist_add_variable(
&vl, name1, name1_len,
ASN_TYPE, &val1, val1_len);
snmp_varlist_add_variable(
&vl, name2, name2_len,
ASN_TYPE, &val2, val2_len);
In both cases, the routine will return a pointer to the new varbind structure (or NULL if the varbind
creation fails).
snmp_add_null_var is a convenience function to add an empty varbind to the PDU. without needing to
specify the NULL value explicitly. This is the normal mechanism for constructing a GET (or similar)
information retrieval request.
Again, this returns a pointer to the new varbind, or NULL.
snmp_clone_varbind creates a copy of each varbind in the specified list, returning a pointer to the head
of the new list (or NULL if the cloning fails).
Settingofvaluessnmp_set_var_objid sets the name of the varbind structure to the specified OID.
snmp_set_var_typed_value sets the syntax type and value of the varbind structure.
snmp_set_var_value sets the value of the varbind structure, leaving the syntax type unchanged.
snmp_set_var_typed_integer is a convenience function to set the syntax type and value for a 32-bit
integer-based varbind.
All four of these return 0 if the assignment is successful, or 1 if it is not.
Outputprint_variable will take an object identifier (as returned by read_objid, snmp_parse_oid or
get_module_node) and an instance of such a variable, and prints to the standard output the textual form
of the object identifier together with the value of the variable.
fprint_variable does the same, but prints to the FILE pointer specified by the initial parameter.
snprint_variable prints the same information into the buffer pointed to by buf which is of length len.
It returns the number of characters printed, or -1 if the buffer was not large enough. In the latter
case, buf will typically contained a truncated version of the information (but this behaviour is not
guaranteed). This function replaces the obsolete function sprint_variable.
print_value, fprint_value, and snprint_value do the same as the equivalent print_variable routines, but
only displaying the value of the variable, without the corresponding object identifier.
For displaying the OID of a varbind, see netsnmp_mib_api(3).
Deletionsnmp_free_var releases all memory used by the given varbind structure.
snmp_free_varbind releases all memory used by each varbind structure in the varbind list provided.
Name
snmp_pdu_add_variable, snmp_varlist_add_variable, snmp_add_null_var, snmp_clone_varbind,
snmp_set_var_objid, snmp_set_var_value, snmp_set_var_typed_value, snmp_set_var_typed_integer,
print_variable, fprint_variable, snprint_variable, print_value, fprint_value, snprint_value,
snmp_free_var, snmp_free_varbind - netsnmp_varbind_api functions
See Also
netsnmp_pdu_api(3) netsnmp_mib_api(3) V5.9.4.pre2 13 Aug 2010 NETSNMP_VARBIND_API(3)
Synopsis
#include<net-snmp/varbind_api.h>Creationnetsnmp_variable_list*snmp_pdu_add_variable(netsnmp_pdu*pdu,constoid*objid,size_tobjidlen,u_chartype,constvoid*value,size_tlen);netsnmp_variable_list*snmp_varlist_add_variable(netsnmp_variable_list*varlist,constoid*objid,size_tobjidlen,u_chartype,constvoid*value,size_tlen);netsnmp_variable_list*snmp_add_null_var(netsnmp_pdu*pdu,constoid*objid,size_tobjidlen);netsnmp_variable_list*snmp_clone_varbind(netsnmp_variable_list*varlist);SettingValuesintsnmp_set_var_objid(netsnmp_variable_list*variable,constoid*objid,size_tobjidlen);intsnmp_set_var_value(netsnmp_variable_list*variable,constvoid*value,size_tvallen);intsnmp_set_var_typed_value(netsnmp_variable_list*variable,u_chartype,constvoid*value,size_tvallen);intsnmp_set_var_typed_integer(netsnmp_variable_list*variable,u_chartype,longvalue);Outputvoidprint_variable(constoid*objid,size_tobjidlen,constnetsnmp_variable_list*variable);voidfprint_variable(FILE*fp,constoid*objid,size_tobjidlen,constnetsnmp_variable_list*variable);intsnprint_variable(char*buf,size_tlen,constoid*objid,size_tobjidlen,constnetsnmp_variable_list*variable);voidprint_value(constoid*objid,size_tobjidlen,constnetsnmp_variable_list*variable);voidfprint_value(FILE*fp,constoid*objid,size_tobjidlen,constnetsnmp_variable_list*variable);intsnprint_value(char*buf,size_tlen,constoid*objid,size_tobjidlen,constnetsnmp_variable_list*variable);Deletionvoidsnmp_free_var(netsnmp_variable_list*variable);voidsnmp_free_varbind(netsnmp_variable_list*variables);
