MIB_API(3)MIB_API(3)NAME
init_mib, add_mibdir, init_mib_internals, add_mod
ule_replacement, read_module, read_mib, read_all_mibs,
read_objid, read_module_node, get_module_node, read_objid
snmp_set_mib_warnings, snmp_set_save_descriptions, shut
down_mib, print_mib, print_variable, print_value,
print_objid, print_description - mib_api functions
SYNOPSIS
#include <stdio.h>
#include <sys/types.h>
#include <ucd-snmp/asn1.h>
#include <ucd-snmp/mib.h>
#include <ucd-snmp/parse.h>
void init_mib( void )
int add_mibdir( char *dirname )
int add_module_replacement( char *old_module, char
*new_module, char *tag, int len )
void init_mib_internals( void )
struct tree *read_module( char *name )
struct tree *read_mib( char *filename )
struct tree *read_all_mibs( void )
void shutdown_mib( void )
void print_mib( FILE *fp)
int read_objid( char *input, oid *output, int *out_len)
int get_module_node( char *name, char *module, oid *objid,
int *objidlen )
void print_variable( oid *objid, int objidlen, struct
variable_list *variable)
void print_value( oid *objid, int objidlen, struct vari
able_list *variable)
void print_objid( oid *objid, int objidlen);
void print_description( oid *objid, int objidlen);
void snmp_set_mib_warnings( int );
void snmp_set_save_descriptions( int );
DESCRIPTION
The functions dealing with MIB modules fall into four
groups. Those dealing with initialisation, those that
read in and parse MIB files, those that search the MIB
tree, and various output routines.
init_mib is a convenience function that handles all calls
to add_mibdir, read_module and read_mib for standard
applications. It should be called before any other rou
tine that manipulates or accesses the MIB tree. This rou
tine sets up various internal structures, as well as read
ing in the default MIB modules, as detailed below.
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add_mibdir is used to define the range of directory loca
tions which are searched for files containing MIB modules
(one module per file). By default, this will be set to
the directory DATADIR/mibs but this can be overridden by
setting the environment variable MIBDIRS to a (colon-sepa
rated) list of directories to search. Note that this does
not actually load the MIB modules located in that direc
tory, but is an initialisation step to make them avail
able. This function returns a count of files found in the
directory, or a -1 if there is an error.
init_mib_internals sets up the internal structures,
preparatory to reading in MIB modules. It should be
called after all calls to add_mibdir, and before and calls
to read_module. This is called automatically if init_mib
is used.
add_module_replacement can be used to allow new MIB mod
ules 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.
tab(+); lb lb lb l l l. 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 identi
fiers used in MIB import clauses (such as referring to
RFC1213 instead of RFC1213-MIB ).
read_module locates and parses the module specified,
together with any modules that it imports from, and adds
the contents of these modules to the active MIB tree.
Note that add_mibdir must first be called to add the
directory containing the file with the module definition,
if this is not in the standard path.
By default, the following mib modules will be loaded: IP-
MIB, IF-MIB, TCP-MIB, UDP-MIB, SNMPv2-MIB, RFC1213-MIB,
UCD-SNMP-MIB. This can be overridden by setting the envi
ronment variable MIBS to a (colon-separated) list of mod
ules to load. If this variable starts with a plus charac
ter, then the specified modules are added to the default
list. Otherwise only those modules listed are loaded
(together with any others they import from). If MIBS is
set to ALL, read_all_mibs is called to load all the MIB
files found in all the specified MIBDIRS.
read_mib parses the file specified, together with any mod
ules that it imports from, and adds the contents to the
active MIB tree. Such a file can contain more then one
module, though care must be taken that any imports occur
earlier in the file, if they are not to be read from the
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installed modules. Note that the file specified does not
need to be in any of the directories initialised by
add_mibdir (or the default setup), though any imported
modules do.
The environment variable MIBFILES can be set to a (colon-
separated) list of files containing mibs to load.
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 parame
ter, with the number of sub-identifiers returned via
out_len. When called, out_len must hold the maximum
length of the output array. This function returns a value
of 1 if it succeeds in parsing the string and 0 otherwise.
get_module_node takes a descriptor and the name of a mod
ule, and returns the corresponding oid list, in the same
way as read_objid above.
If the module name is specified as "ANY", then this rou
tine 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.
shutdown_mib will clear the information that was gathered
by read_module, add_mibdir,and add_module_replacement. It
is strongly recommended that one does not invoke shut_
down_mib while there are SNMP sessions being actively man
aged.
print_mib will print out a representation of the currently
active MIB tree to the specified FILE pointer.
print_variable will take an object identifier (as returned
by read_objid or get_module_node ) and an instance of such
a variable, and prints out the textual form of the object
identifier together with the value of the variable.
A related routine sprint_variable takes an initial parame
ter of a string buffer, in which to print this informa
tion.
print_value and sprint_value do the same as the equivalent
print_variable routines, but only displaying the value of
the variable, without the corresponding object identifier>
print_objid and sprint_objid
take an object identifier (without an accompanying vari
able instance) and print out the textual representation.
Note that identifiers lying within the mib-2, experimental
or private subtrees are listed from this point onwards,
rather than with the full object identifier.
print_description takes an object identifier (as for
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print_objid above) and prints out the associated descrip
tion. Note that there is no corresponding routine
sprint_description
By default the parser does not save descriptions - they
may be huge. In order to be able to print them, you must
call snmp_set_save_descriptions(1).
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 parameter of 1 (or 2 for even
more warnings).
ENVIRONMENT VARIABLES
MIBDIRS A colon separated list of directories to search
for MIB modules. Default: LIBDIR/snmp/mibs
MIBFILES A colon separated list of files to load.
Default: (none)
MIBS A colon separated list of MIB modules to load.
Default: IP-MIB:IF-MIB:TCP-MIB:UDP-
MIB:SNMPv2-MIB:RFC1213-MIB:UCD-SNMP-MIB.
SEE ALSOsnmp_api(3)
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