1NETSNMP_MIB_API(3) Net-SNMP NETSNMP_MIB_API(3)
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6 add_mibdir, netsnmp_init_mib, shutdown_mib, netsnmp_read_module,
7 read_mib, read_all_mibs, add_module_replacement, snmp_set_mib_errors,
8 snmp_set_mib_warnings, snmp_set_save_descriptions, read_objid,
9 snmp_parse_oid, get_module_node, print_mib, print_objid, fprint_objid,
10 snprint_objid, print_description, fprint_description, snprint_descrip‐
11 tion - netsnmp_mib_api functions
12
14 #include <net-snmp/mib_api.h>
15 Initialisation and Shutdown
17 int add_mibdir(const char *dirname);
18 void netsnmp_init_mib(void);
20 void shutdown_mib(void);
21 Reading and Parsing MIBs
23 struct tree *netsnmp_read_module(const char *name);
24 struct tree *read_mib(const char *filename);
25 struct tree *read_all_mibs(void);
26 int add_module_replacement(const char *old_module,
28 const char *new_module,
29 const char *tag, int len);
30 void snmp_set_mib_warnings(int level);
32 void snmp_set_mib_errors(int level);
33 void snmp_set_save_descriptions(int save);
34 Searching the MIB Tree
36 int read_objid(const char *input,
37 oid *objid, size_t *objidlen);
38 oid *snmp_parse_oid(const char *input,
39 oid *objid, size_t *objidlen);
40 int get_module_node(const char *name, const char *module,
41 oid *objid, size_t *objidlen);
42 Output
44 void print_mib(FILE *fp);
45 void print_objid(const oid *objid, size_t objidlen);
47 void fprint_objid(FILE *fp,
48 const oid *objid, size_t objidlen);
49 int snprint_objid(char *buf, size_t len,
50 const oid *objid, size_t objidlen);
51 void print_description(const oid *objid, size_t objidlen, int width);
53 void fprint_description(FILE *fp,
54 const oid *objid, size_t objidlen, int width);
55 int snprint_description(char *buf, size_t len,
56 const oid *objid, size_t objidlen, int width);
57
59 The functions dealing with MIB modules fall into four groups - those
60 dealing with initialisation and shutdown, with reading in and parsing
61 MIB files, with searching the MIB tree, and output routines.
62 Initialisation and Shutdown
64 add_mibdir is used to add the specified directory to the path of loca‐
65 tions which are searched for files containing MIB modules. Note that
66 this does not actually load the MIB modules located in that directory,
67 but is simply an initialisation step to make them available to net‐
68 snmp_read_module. This function returns a count of files found in the
69 directory, or a -1 if there is an error. It should be called before
70 invoking netsnmp_init_mib.
71 netsnmp_init_mib configures the MIB directory search path (using
73 add_mibdir ), sets up the internal MIB framework, and then loads the
74 appropriate MIB modules (using netsnmp_read_module and read_mib). See
75 the ENVIRONMENTAL VARIABLES section for details.
76 It should be called before any other routine that manipulates or
77 accesses the MIB tree (but after any additional add_mibdir calls).
78 shutdown_mib will clear the information that was gathered by net‐
80 snmp_read_module, add_mibdir and add_module_replacement. It is
81 strongly recommended that one does not invoke shutdown_mib while there
82 are SNMP sessions being actively managed.
83 Reading and Parsing MIBs
85 netsnmp_read_module takes the name of a MIB module (which need not be
86 the same as the name of the file that contains the module), locates
87 this within the configured list of MIB directories, and loads the defi‐
88 nitions from the module into the active MIB tree. It also loads any
89 MIB modules listed in the IMPORTS clause of this module.
90 read_mib is similar, but takes the name of the file containing the MIB
92 module. Note that this file need not be located within the MIB direc‐
93 tory search list (although any modules listed in the IMPORTS clause
94 do).
95 read_all_mibs will read in all the MIB modules found on the MIB direc‐
97 tory search list.
98 In general the parser is silent about what strangenesses it sees in the
100 MIB files. To get warnings reported, call snmp_set_mib_warnings with a
101 level of 1 (or 2 for even more warnings).
102 add_module_replacement can be used to allow new MIB modules to obsolete
104 older ones, without needing to amend the IMPORTS clauses of other mod‐
105 ules. It takes the names of the old and new modules, together with an
106 indication of which portions of the old module are affected.
107 tag len load the new module when:
109 NULL 0 always (the old module is a strict subset of
110 the new)
111 name 0 for the given tag only
112 name non-0 for any identifier with this prefix
113 It can also be used to handle errors in the module identifiers used in
114 MIB IMPORTS clauses (such as referring to RFC1213 instead of
115 RFC1213-MIB).
116 Searching the MIB Tree
118 read_objid takes a string containing a textual version of an object
119 identifier (in either numeric or descriptor form), and transforms this
120 into the corresponding list of sub-identifiers. This is returned in
121 the output parameter, with the number of sub-identifiers returned via
122 out_len. When called, out_len must hold the maximum length of the out‐
123 put array. If multiple object identifiers are being processed, then
124 this length should be reset before each call. This function returns a
125 value of 1 if it succeeds in parsing the string and 0 otherwise.
126 snmp_parse_oid is similar, but returns a pointer to the parsed OID buf‐
128 fer (or NULL).
129 get_module_node takes a descriptor and the name of a module, and
131 returns the corresponding oid list, in the same way as read_objid
132 above.
133 If the module name is specified as "ANY", then this routine will assume
134 that the descriptor given is unique within the tree, and will return
135 the matching entry. If this assumption is invalid, then the behaviour
136 as to which variable is returned is implementation dependent.
137 Output
139 print_mib will print out a representation of the currently active MIB
140 tree to the specified FILE pointer.
141 print_objid will take an object identifier (as returned by read_objid,
143 snmp_parse_oid or get_module_node), and prints the textual form of this
144 OID to the standard output.
145 fprint_objid does the same, but prints to the FILE pointer specified by
147 the initial parameter.
148 snprint_objid prints the same information into the buffer pointed to by
150 buf which is of length len. It returns the number of characters
151 printed, or -1 if the buffer was not large enough. In the latter case,
152 buf will typically contain a truncated version of the information (but
153 this behaviour is not guaranteed).
154 print_description, fprint_description, and snprint_description take a
156 similar object identifier and print out a version of the MIB definition
157 for that object, together with the full OID. The width argument con‐
158 trols how the OID is layed out.
159 By default the parser does not save descriptions since they may be
161 huge. In order to be able to print them, it is necessary to invoke
162 snmp_set_save_descriptions(1)before calling init_mib (or similar).
163
165 The main use of environmental variables with respect to these API calls
166 is to configure which MIB modules should be loaded, and where they are
167 located.
168 MIBDIRS A colon separated list of directories to search for MIB mod‐
170 ules.
171 Default: /usr/share/snmp/mibs
172 Used by init_mib, netsnmp_read_module, read_all_mibs and
173 (implicitly) by read_mib.
174 MIBS A colon separated list of MIB modules to load.
176 The default list of modules will depend on how the Net-SNMP
177 software was originally compiled, but is typically:
178 IP-MIB:IF-MIB:TCP-MIB:UDP-MIB:SNMPv2-MIB:RFC1213-MIB:
179 UCD-SNMP-MIB:HOST-RESOURCES-MIB
180 If the value of the MIBS environmental variable starts with a
182 '+' character, then these MIB modules will be added to the
183 default list. Otherwise these modules (plus any that they
184 IMPORT from) will be loaded instead of the default list.
185 If the MIBS environmental variable has the value ALL then
187 read_all_mibs will be called to load the full collection of
188 all available MIB modules.
189 Used by init_mib only.
191 MIBFILES A colon separated list of files to load.
193 Default: (none)
194 Used by init_mib only.
195
197 netsnmp_session_api(3), netsnmp_pdu_api(3), netsnmp_varbind_api(3)
198V5.9 13 Aug 2010 NETSNMP_MIB_API(3)