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NETSNMP_MIB_API(3) Net-SNMP NETSNMP_MIB_API(3)
NAME
add_mibdir, netsnmp_init_mib, shutdown_mib, netsnmp_read_module,
read_mib, read_all_mibs, add_module_replacement, snmp_set_mib_errors,
snmp_set_mib_warnings, snmp_set_save_descriptions, read_objid,
snmp_parse_oid, get_module_node, print_mib, print_objid, fprint_objid,
snprint_objid, print_description, fprint_description,
snprint_description - netsnmp_mib_api functions
SYNOPSIS
#include <net-snmp/mib_api.h>
Initialisation and Shutdown
int add_mibdir(const char *dirname);
void netsnmp_init_mib(void);
void shutdown_mib(void);
Reading and Parsing MIBs
struct tree *netsnmp_read_module(const char *name);
struct tree *read_mib(const char *filename);
struct tree *read_all_mibs(void);
int add_module_replacement(const char *old_module,
const char *new_module,
const char *tag, int len);
void snmp_set_mib_warnings(int level);
void snmp_set_mib_errors(int level);
void snmp_set_save_descriptions(int save);
Searching the MIB Tree
int read_objid(const char *input,
oid *objid, size_t *objidlen);
oid *snmp_parse_oid(const char *input,
oid *objid, size_t *objidlen);
int get_module_node(const char *name, const char *module,
oid *objid, size_t *objidlen);
Output
void print_mib(FILE *fp);
void print_objid(const oid *objid, size_t objidlen);
void fprint_objid(FILE *fp,
const oid *objid, size_t objidlen);
int snprint_objid(char *buf, size_t len,
const oid *objid, size_t objidlen);
void print_description(const oid *objid, size_t objidlen, int width);
void fprint_description(FILE *fp,
const oid *objid, size_t objidlen, int width);
int snprint_description(char *buf, size_t len,
const oid *objid, size_t objidlen, int width);
DESCRIPTION
The functions dealing with MIB modules fall into four groups - those
dealing with initialisation and shutdown, with reading in and parsing
MIB files, with searching the MIB tree, and output routines.
Initialisation and Shutdown
add_mibdir is used to add the specified directory to the path of
locations which are searched for files containing MIB modules. Note
that this does not actually load the MIB modules located in that
directory, but is simply an initialisation step to make them available
to netsnmp_read_module. This function returns a count of files found
in the directory, or a -1 if there is an error. It should be called
before invoking netsnmp_init_mib.
netsnmp_init_mib configures the MIB directory search path (using
add_mibdir ), sets up the internal MIB framework, and then loads the
appropriate MIB modules (using netsnmp_read_module and read_mib). See
the ENVIRONMENTAL VARIABLES section for details.
It should be called before any other routine that manipulates or
accesses the MIB tree (but after any additional add_mibdir calls).
shutdown_mib will clear the information that was gathered by
netsnmp_read_module, add_mibdir and add_module_replacement. It is
strongly recommended that one does not invoke shutdown_mib while there
are SNMP sessions being actively managed.
Reading and Parsing MIBs
netsnmp_read_module takes the name of a MIB module (which need not be
the same as the name of the file that contains the module), locates
this within the configured list of MIB directories, and loads the
definitions from the module into the active MIB tree. It also loads
any MIB modules listed in the IMPORTS clause of this module.
read_mib is similar, but takes the name of the file containing the MIB
module. Note that this file need not be located within the MIB
directory search list (although any modules listed in the IMPORTS
clause do).
read_all_mibs will read in all the MIB modules found on the MIB
directory search list.
In general the parser is silent about what strangenesses it sees in the
MIB files. To get warnings reported, call snmp_set_mib_warnings with a
level of 1 (or 2 for even more warnings).
add_module_replacement can be used to allow new MIB modules to obsolete
older ones, without needing to amend the IMPORTS clauses of other
modules. It takes the names of the old and new modules, together with
an indication of which portions of the old module are affected.
tag len load the new module when:
NULL 0 always (the old module is a strict subset of
the new)
name 0 for the given tag only
name non-0 for any identifier with this prefix
It can also be used to handle errors in the module identifiers used in
MIB IMPORTS clauses (such as referring to RFC1213 instead of
RFC1213-MIB).
Searching the MIB Tree
read_objid takes a string containing a textual version of an object
identifier (in either numeric or descriptor form), and transforms this
into the corresponding list of sub-identifiers. This is returned in
the output parameter, with the number of sub-identifiers returned via
out_len. When called, out_len must hold the maximum length of the
output array. If multiple object identifiers are being processed, then
this length should be reset before each call. This function returns a
value of 1 if it succeeds in parsing the string and 0 otherwise.
snmp_parse_oid is similar, but returns a pointer to the parsed OID
buffer (or NULL).
get_module_node takes a descriptor and the name of a module, and
returns the corresponding oid list, in the same way as read_objid
above.
If the module name is specified as "ANY", then this routine will assume
that the descriptor given is unique within the tree, and will return
the matching entry. If this assumption is invalid, then the behaviour
as to which variable is returned is implementation dependent.
Output
print_mib will print out a representation of the currently active MIB
tree to the specified FILE pointer.
print_objid will take an object identifier (as returned by read_objid,
snmp_parse_oid or get_module_node), and prints the textual form of this
OID to the standard output.
fprint_objid does the same, but prints to the FILE pointer specified by
the initial parameter.
snprint_objid 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 contain a truncated version of the information (but
this behaviour is not guaranteed).
print_description, fprint_description, and snprint_description take a
similar object identifier and print out a version of the MIB definition
for that object, together with the full OID. The width argument
controls how the OID is layed out.
By default the parser does not save descriptions since they may be
huge. In order to be able to print them, it is necessary to invoke
snmp_set_save_descriptions(1)before calling init_mib (or similar).
ENVIRONMENT VARIABLES
The main use of environmental variables with respect to these API calls
is to configure which MIB modules should be loaded, and where they are
located.
MIBDIRS A colon separated list of directories to search for MIB
modules.
Default: /usr/local/share/snmp/mibs
Used by init_mib, netsnmp_read_module, read_all_mibs and
(implicitly) by read_mib.
MIBS A colon separated list of MIB modules to load.
The default list of modules will depend on how the Net-SNMP
software was originally compiled, but is typically:
IP-MIB:IF-MIB:TCP-MIB:UDP-MIB:SNMPv2-MIB:RFC1213-MIB:
UCD-SNMP-MIB:HOST-RESOURCES-MIB
If the value of the MIBS environmental variable starts with a
'+' character, then these MIB modules will be added to the
default list. Otherwise these modules (plus any that they
IMPORT from) will be loaded instead of the default list.
If the MIBS environmental variable has the value ALL then
read_all_mibs will be called to load the full collection of
all available MIB modules.
Used by init_mib only.
MIBFILES A colon separated list of files to load.
Default: (none)
Used by init_mib only.
SEE ALSO
netsnmp_session_api(3), netsnmp_pdu_api(3), netsnmp_varbind_api(3)
V5.7.3 13 Aug 2010 NETSNMP_MIB_API(3)