--- name: "mib_api" section: "3" platform: "linux" package: "libsnmp4.1-dev" version: "4.1.1-2.2" release: "Debian 2.2 (Potato)" platforms: ["linux"] url: "https://new.carta.tech/mib_api" --- # mib\_api(3) ## NAME init\_mib, add\_mibdir, init\_mib\_internals, read\_module, read\_mib, read\_all\_mibs, read\_objid, read\_module\_node, print\_mib, print\_variable, print\_value, print\_objid, print\_description ## SYNOPSIS **#include \**\ **#include \**\ **#include \**\ **#include \**\ **#include \** **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 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 variable\_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 routine that manipulates or accesses the MIB tree. This routine sets up various internal structures, as well as reading in the default MIB modules, as detailed below. *add\_mibdir* is used to define the range of directory locations 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-separated) list of directories to search. Note that this does not actually load the MIB modules located in that directory, but is an initialisation step to make them available. 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 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 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 environment variable *MIBS* to a (colon-separated) list of modules to load. If this variable starts with a plus character, 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 modules 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 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* parameter, 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 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. *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 parameter of a string buffer, in which to print this information. *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 variable 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 *print\_objid* above) and prints out the associated description. 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 ALSO [snmp\_api(3)](/snmp_api/3.md)