NETSNMP_MIB_API
NETSNMP_MIB_API
NAMESYNOPSIS
DESCRIPTION
ENVIRONMENT VARIABLES
SEE ALSO
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.
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/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
snmp_api(3), output_api(3)
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