1.\"
| 1.\"
|
| 2.\" Copyright (c) 2010 The FreeBSD Foundation
3.\" All rights reserved.
4.\"
5.\" Portions of this documentation were written by Shteryana Sotirova Shopova
6.\" under sponsorship from the FreeBSD Foundation.
7.\"
|
2.\" Copyright (c) 2004-2005
3.\" Hartmut Brandt.
4.\" All rights reserved.
5.\" Copyright (c) 2001-2003
6.\" Fraunhofer Institute for Open Communication Systems (FhG Fokus).
7.\" All rights reserved.
8.\"
9.\" Author: Harti Brandt <harti@FreeBSD.org>
10.\"
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12.\" modification, are permitted provided that the following conditions
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14.\" 1. Redistributions of source code must retain the above copyright
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18.\" documentation and/or other materials provided with the distribution.
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22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23.\" ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
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27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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32.\" $Begemot: bsnmp/lib/bsnmplib.3,v 1.9 2005/10/04 08:46:51 brandt_h Exp $
33.\"
| 8.\" Copyright (c) 2004-2005
9.\" Hartmut Brandt.
10.\" All rights reserved.
11.\" Copyright (c) 2001-2003
12.\" Fraunhofer Institute for Open Communication Systems (FhG Fokus).
13.\" All rights reserved.
14.\"
15.\" Author: Harti Brandt <harti@FreeBSD.org>
16.\"
17.\" Redistribution and use in source and binary forms, with or without
18.\" modification, are permitted provided that the following conditions
19.\" are met:
20.\" 1. Redistributions of source code must retain the above copyright
21.\" notice, this list of conditions and the following disclaimer.
22.\" 2. Redistributions in binary form must reproduce the above copyright
23.\" notice, this list of conditions and the following disclaimer in the
24.\" documentation and/or other materials provided with the distribution.
25.\"
26.\" THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
27.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29.\" ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
30.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36.\" SUCH DAMAGE.
37.\"
38.\" $Begemot: bsnmp/lib/bsnmplib.3,v 1.9 2005/10/04 08:46:51 brandt_h Exp $
39.\"
|
34.Dd October 4, 2005
| 40.Dd September 9, 2010
|
35.Dt BSNMPLIB 3
36.Os
37.Sh NAME
38.Nm snmp_value_free ,
39.Nm snmp_value_parse ,
40.Nm snmp_value_copy ,
41.Nm snmp_pdu_free ,
| 41.Dt BSNMPLIB 3
42.Os
43.Sh NAME
44.Nm snmp_value_free ,
45.Nm snmp_value_parse ,
46.Nm snmp_value_copy ,
47.Nm snmp_pdu_free ,
|
42.Nm snmp_code snmp_pdu_decode ,
43.Nm snmp_code snmp_pdu_encode ,
| 48.Nm snmp_pdu_decode ,
49.Nm snmp_pdu_encode ,
50.Nm snmp_pdu_decode_header ,
51.Nm snmp_pdu_decode_scoped ,
52.Nm snmp_pdu_decode_secmode ,
|
44.Nm snmp_pdu_dump ,
| 53.Nm snmp_pdu_dump ,
|
| 54.Nm snmp_passwd_to_keys ,
55.Nm snmp_get_local_keys ,
56.Nm snmp_calc_keychange ,
|
45.Nm TRUTH_MK ,
46.Nm TRUTH_GET ,
47.Nm TRUTH_OK
48.Nd "SNMP decoding and encoding library"
49.Sh LIBRARY
50Begemot SNMP library
51.Pq libbsnmp, -lbsnmp
52.Sh SYNOPSIS
53.In bsnmp/asn1.h
54.In bsnmp/snmp.h
55.Ft void
56.Fn snmp_value_free "struct snmp_value *value"
57.Ft int
58.Fn snmp_value_parse "const char *buf" "enum snmp_syntax" "union snmp_values *value"
59.Ft int
60.Fn snmp_value_copy "struct snmp_value *to" "const struct snmp_value *from"
61.Ft void
62.Fn snmp_pdu_free "struct snmp_pdu *value"
63.Ft enum snmp_code
64.Fn snmp_pdu_decode "struct asn_buf *buf" "struct snmp_pdu *pdu" "int32_t *ip"
65.Ft enum snmp_code
66.Fn snmp_pdu_encode "struct snmp_pdu *pdu" "struct asn_buf *buf"
| 57.Nm TRUTH_MK ,
58.Nm TRUTH_GET ,
59.Nm TRUTH_OK
60.Nd "SNMP decoding and encoding library"
61.Sh LIBRARY
62Begemot SNMP library
63.Pq libbsnmp, -lbsnmp
64.Sh SYNOPSIS
65.In bsnmp/asn1.h
66.In bsnmp/snmp.h
67.Ft void
68.Fn snmp_value_free "struct snmp_value *value"
69.Ft int
70.Fn snmp_value_parse "const char *buf" "enum snmp_syntax" "union snmp_values *value"
71.Ft int
72.Fn snmp_value_copy "struct snmp_value *to" "const struct snmp_value *from"
73.Ft void
74.Fn snmp_pdu_free "struct snmp_pdu *value"
75.Ft enum snmp_code
76.Fn snmp_pdu_decode "struct asn_buf *buf" "struct snmp_pdu *pdu" "int32_t *ip"
77.Ft enum snmp_code
78.Fn snmp_pdu_encode "struct snmp_pdu *pdu" "struct asn_buf *buf"
|
| 79.Ft enum snmp_code
80.Fn snmp_pdu_decode_header "struct snmp_pdu *pdu" "struct asn_buf *buf"
81.Ft enum snmp_code
82.Fn snmp_pdu_decode_scoped "struct asn_buf *buf" "struct snmp_pdu *pdu" "int32_t *ip"
83.Ft enum snmp_code
84.Fn snmp_pdu_decode_secmode "struct asn_buf *buf" "struct snmp_pdu *pdu"
|
67.Ft void
68.Fn snmp_pdu_dump "const struct snmp_pdu *pdu"
| 85.Ft void
86.Fn snmp_pdu_dump "const struct snmp_pdu *pdu"
|
| 87.Ft enum snmp_code
88.Fn snmp_passwd_to_keys "struct snmp_user *user" "char *passwd"
89.Ft enum snmp_code
90.Fn snmp_get_local_keys "struct snmp_user *user" "uint8_t *eid" "uint32_t elen"
91.Ft enum snmp_code
92.Fn snmp_calc_keychange "struct snmp_user *user" "uint8_t *keychange"
|
69.Ft int
70.Fn TRUTH_MK "F"
71.Ft int
72.Fn TRUTH_GET "T"
73.Ft int
74.Fn TRUTH_OK "T"
75.Sh DESCRIPTION
| 93.Ft int
94.Fn TRUTH_MK "F"
95.Ft int
96.Fn TRUTH_GET "T"
97.Ft int
98.Fn TRUTH_OK "T"
99.Sh DESCRIPTION
|
76The SNMP library contains routines to handle SNMP version 1 and 2 PDUs.
77There are two basic structures used throughout the library:
| 100The SNMP library contains routines to handle SNMP version 1, 2 and 3 PDUs.
101There are several basic structures used throughout the library:
|
78.Bd -literal -offset indent
79struct snmp_value {
80 struct asn_oid var;
81 enum snmp_syntax syntax;
82 union snmp_values {
83 int32_t integer;/* also integer32 */
84 struct {
85 u_int len;
86 u_char *octets;
87 } octetstring;
88 struct asn_oid oid;
89 u_char ipaddress[4];
90 uint32_t uint32; /* also gauge32, counter32,
91 unsigned32, timeticks */
92 uint64_t counter64;
93 } v;
94};
95.Ed
96.Pp
97This structure represents one variable binding from an SNMP PDU.
98The field
99.Fa var
100is the ASN.1 of the variable that is bound.
101.Fa syntax
102contains either the syntax code of the value or an exception code for SNMPv2
103and may be one of:
104.Bd -literal -offset indent
105enum snmp_syntax {
106 SNMP_SYNTAX_NULL = 0,
107 SNMP_SYNTAX_INTEGER, /* == INTEGER32 */
108 SNMP_SYNTAX_OCTETSTRING,
109 SNMP_SYNTAX_OID,
110 SNMP_SYNTAX_IPADDRESS,
111 SNMP_SYNTAX_COUNTER,
112 SNMP_SYNTAX_GAUGE, /* == UNSIGNED32 */
113 SNMP_SYNTAX_TIMETICKS,
114
115 /* v2 additions */
116 SNMP_SYNTAX_COUNTER64,
117 /* exceptions */
118 SNMP_SYNTAX_NOSUCHOBJECT,
119 SNMP_SYNTAX_NOSUCHINSTANCE,
120 SNMP_SYNTAX_ENDOFMIBVIEW,
121};
122.Ed
123The field
124.Fa v
125holds the actual value depending on
126.Fa syntax .
127Note, that if
128.Fa syntax
129is
130.Li SNMP_SYNTAX_OCTETSTRING
131and
132.Fa v.octetstring.len
133is not zero,
134.Fa v.octetstring.octets
135points to a string allocated by
136.Xr malloc 3 .
| 102.Bd -literal -offset indent
103struct snmp_value {
104 struct asn_oid var;
105 enum snmp_syntax syntax;
106 union snmp_values {
107 int32_t integer;/* also integer32 */
108 struct {
109 u_int len;
110 u_char *octets;
111 } octetstring;
112 struct asn_oid oid;
113 u_char ipaddress[4];
114 uint32_t uint32; /* also gauge32, counter32,
115 unsigned32, timeticks */
116 uint64_t counter64;
117 } v;
118};
119.Ed
120.Pp
121This structure represents one variable binding from an SNMP PDU.
122The field
123.Fa var
124is the ASN.1 of the variable that is bound.
125.Fa syntax
126contains either the syntax code of the value or an exception code for SNMPv2
127and may be one of:
128.Bd -literal -offset indent
129enum snmp_syntax {
130 SNMP_SYNTAX_NULL = 0,
131 SNMP_SYNTAX_INTEGER, /* == INTEGER32 */
132 SNMP_SYNTAX_OCTETSTRING,
133 SNMP_SYNTAX_OID,
134 SNMP_SYNTAX_IPADDRESS,
135 SNMP_SYNTAX_COUNTER,
136 SNMP_SYNTAX_GAUGE, /* == UNSIGNED32 */
137 SNMP_SYNTAX_TIMETICKS,
138
139 /* v2 additions */
140 SNMP_SYNTAX_COUNTER64,
141 /* exceptions */
142 SNMP_SYNTAX_NOSUCHOBJECT,
143 SNMP_SYNTAX_NOSUCHINSTANCE,
144 SNMP_SYNTAX_ENDOFMIBVIEW,
145};
146.Ed
147The field
148.Fa v
149holds the actual value depending on
150.Fa syntax .
151Note, that if
152.Fa syntax
153is
154.Li SNMP_SYNTAX_OCTETSTRING
155and
156.Fa v.octetstring.len
157is not zero,
158.Fa v.octetstring.octets
159points to a string allocated by
160.Xr malloc 3 .
|
| 161.Pp
|
137.Bd -literal -offset indent
| 162.Bd -literal -offset indent
|
138#define SNMP_COMMUNITY_MAXLEN 128
139#define SNMP_MAX_BINDINGS 100
| 163#define SNMP_ENGINE_ID_SIZ 32
|
140
| 164
|
| 165struct snmp_engine {
166 uint8_t engine_id[SNMP_ENGINE_ID_SIZ];
167 uint32_t engine_len;
168 int32_t engine_boots;
169 int32_t engine_time;
170 int32_t max_msg_size;
171};
172.Ed
173.Pp
174This structure represents an SNMP engine as specified by the SNMP Management
175Architecture described in RFC 3411.
176.Pp
177.Bd -literal -offset indent
178#define SNMP_USM_NAME_SIZ (32 + 1)
179#define SNMP_AUTH_KEY_SIZ 40
180#define SNMP_PRIV_KEY_SIZ 32
181
182struct snmp_user {
183 char sec_name[SNMP_USM_NAME_SIZ];
184 enum snmp_authentication auth_proto;
185 enum snmp_privacy priv_proto;
186 uint8_t auth_key[SNMP_AUTH_KEY_SIZ];
187 uint8_t priv_key[SNMP_PRIV_KEY_SIZ];
188};
189.Ed
190.Pp
191This structure represents an SNMPv3 user as specified by the User-based
192Security Model (USM) described in RFC 3414. The field
193.Fa sec_name
194is a human readable string containing the security user name.
195.Fa auth_proto
196contains the id of the authentication protocol in use by the user and may be one
197of:
198.Bd -literal -offset indent
199enum snmp_authentication {
200 SNMP_AUTH_NOAUTH = 0,
201 SNMP_AUTH_HMAC_MD5,
202 SNMP_AUTH_HMAC_SHA
203};
204.Ed
205.Fa priv_proto
206contains the id of the privacy protocol in use by the user and may be one
207of:
208.Bd -literal -offset indent
209enum snmp_privacy {
210 SNMP_PRIV_NOPRIV = 0,
211 SNMP_PRIV_DES = 1,
212 SNMP_PRIV_AES
213};
214.Ed
215.Fa auth_key
216and
217.Fa priv_key
218contain the authentication and privacy keys for the user.
219.Pp
220.Bd -literal -offset indent
221#define SNMP_COMMUNITY_MAXLEN 128
222#define SNMP_MAX_BINDINGS 100
223#define SNMP_CONTEXT_NAME_SIZ (32 + 1)
224#define SNMP_TIME_WINDOW 150
225
226#define SNMP_USM_AUTH_SIZE 12
227#define SNMP_USM_PRIV_SIZE 8
228
229#define SNMP_MSG_AUTH_FLAG 0x1
230#define SNMP_MSG_PRIV_FLAG 0x2
231#define SNMP_MSG_REPORT_FLAG 0x4
232
233#define SNMP_SECMODEL_USM 3
234
|
141struct snmp_pdu {
| 235struct snmp_pdu {
|
142 char community[SNMP_COMMUNITY_MAXLEN + 1];
143 enum snmp_version version;
144 u_int type;
| 236 char community[SNMP_COMMUNITY_MAXLEN + 1];
237 enum snmp_version version;
238 u_int type;
|
145
| 239
|
| 240 /* SNMPv3 PDU header fields */
241 int32_t identifier;
242 uint8_t flags;
243 int32_t security_model;
244 struct snmp_engine engine;
245
246 /* Associated USM user parameters */
247 struct snmp_user user;
248 uint8_t msg_digest[SNMP_USM_AUTH_SIZE];
249 uint8_t msg_salt[SNMP_USM_PRIV_SIZE];
250
251 /* View-based Access Model */
252 uint32_t context_engine_len;
253 uint8_t context_engine[SNMP_ENGINE_ID_SIZ];
254 char context_name[SNMP_CONTEXT_NAME_SIZ];
255
|
146 /* trap only */
| 256 /* trap only */
|
147 struct asn_oid enterprise;
148 u_char agent_addr[4];
149 int32_t generic_trap;
150 int32_t specific_trap;
151 u_int32_t time_stamp;
| 257 struct asn_oid enterprise;
258 u_char agent_addr[4];
259 int32_t generic_trap;
260 int32_t specific_trap;
261 uint32_t time_stamp;
|
152
153 /* others */
| 262
263 /* others */
|
154 int32_t request_id;
155 int32_t error_status;
156 int32_t error_index;
| 264 int32_t request_id;
265 int32_t error_status;
266 int32_t error_index;
|
157
158 /* fixes for encoding */
| 267
268 /* fixes for encoding */
|
159 u_char *outer_ptr;
160 u_char *pdu_ptr;
161 u_char *vars_ptr;
| 269 size_t outer_len;
270 size_t scoped_len;
271 u_char *outer_ptr;
272 u_char *digest_ptr;
273 u_char *encrypted_ptr;
274 u_char *scoped_ptr;
275 u_char *pdu_ptr;
276 u_char *vars_ptr;
|
162
| 277
|
163 struct snmp_value bindings[SNMP_MAX_BINDINGS];
164 u_int nbindings;
| 278
279 struct snmp_value bindings[SNMP_MAX_BINDINGS];
280 u_int nbindings;
|
165};
166.Ed
167This structure contains a decoded SNMP PDU.
168.Fa version
169is one of
170.Bd -literal -offset indent
171enum snmp_version {
172 SNMP_Verr = 0,
173 SNMP_V1 = 1,
174 SNMP_V2c,
| 281};
282.Ed
283This structure contains a decoded SNMP PDU.
284.Fa version
285is one of
286.Bd -literal -offset indent
287enum snmp_version {
288 SNMP_Verr = 0,
289 SNMP_V1 = 1,
290 SNMP_V2c,
|
| 291 SNMP_V3
|
175};
176.Ed
177and
178.Fa type
179is the type of the PDU.
| 292};
293.Ed
294and
295.Fa type
296is the type of the PDU.
|
| 297.Fa security_model
298is the security model used for SNMPv3 PDUs. The only supported
299value currently is 3 (User-based Security Model).
|
180.Pp
181The function
182.Fn snmp_value_free
183is used to free all the dynamic allocated contents of an SNMP value.
184It does not free the structure pointed to by
185.Fa value
186itself.
187.Pp
188The function
189.Fn snmp_value_parse
190parses the ASCII representation of an SNMP value into its binary form.
191This function is mainly used by the configuration file reader of
192.Xr bsnmpd 1 .
193.Pp
194The function
195.Fn snmp_value_copy
196makes a deep copy of the value pointed to by
197.Fa from
198to the structure pointed to by
199.Fa to .
200It assumes that
201.Fa to
202is uninitialized and will overwrite its previous contents.
203It does not itself allocate the structure pointed to by
204.Fa to .
205.Pp
206The function
207.Fn snmp_pdu_free
208frees all the dynamically allocated components of the PDU.
209It does not itself free the structure pointed to by
210.Fa pdu .
211.Pp
212The function
213.Fn snmp_pdu_decode
214decodes the PDU pointed to by
215.Fa buf
216and stores the result into
217.Fa pdu .
218If an error occurs in a variable binding the (1 based) index of this binding
219is stored in the variable pointed to by
220.Fa ip .
221.Pp
222The function
223.Fn snmp_pdu_encode
224encodes the PDU
225.Fa pdu
| 300.Pp
301The function
302.Fn snmp_value_free
303is used to free all the dynamic allocated contents of an SNMP value.
304It does not free the structure pointed to by
305.Fa value
306itself.
307.Pp
308The function
309.Fn snmp_value_parse
310parses the ASCII representation of an SNMP value into its binary form.
311This function is mainly used by the configuration file reader of
312.Xr bsnmpd 1 .
313.Pp
314The function
315.Fn snmp_value_copy
316makes a deep copy of the value pointed to by
317.Fa from
318to the structure pointed to by
319.Fa to .
320It assumes that
321.Fa to
322is uninitialized and will overwrite its previous contents.
323It does not itself allocate the structure pointed to by
324.Fa to .
325.Pp
326The function
327.Fn snmp_pdu_free
328frees all the dynamically allocated components of the PDU.
329It does not itself free the structure pointed to by
330.Fa pdu .
331.Pp
332The function
333.Fn snmp_pdu_decode
334decodes the PDU pointed to by
335.Fa buf
336and stores the result into
337.Fa pdu .
338If an error occurs in a variable binding the (1 based) index of this binding
339is stored in the variable pointed to by
340.Fa ip .
341.Pp
342The function
343.Fn snmp_pdu_encode
344encodes the PDU
345.Fa pdu
|
226into the an octetstring in buffer
| 346into the an octetstring in buffer, and if authentication and privacy are used,
347calculates a message digest and encrypts the PDU data in the buffer
|
227.Fa buf .
228.Pp
229The function
| 348.Fa buf .
349.Pp
350The function
|
| 351.Fn snmp_pdu_decode_header
352decodes the header of the PDU pointed to by
353.Fa buf .
354The uncoded PDU contents remain in the buffer.
355.Pp
356The function
357.Fn snmp_pdu_decode_scoped
358decodes the scoped PDU pointed to by
359.Fa buf .
360.Pp
361The function
362.Fn snmp_pdu_decode_secmode
363verifies the authentication parameter contained in the PDU (if present) and
364if the PDU is encrypted, decrypts the PDU contents pointed to by
365.Fa buf .
366If successfull, a plain text scoped PDU is stored in the buffer.
367.Pp
368The function
|
230.Fn snmp_pdu_dump
231dumps the PDU in a human readable form by calling
232.Fn snmp_printf .
233.Pp
234The function
| 369.Fn snmp_pdu_dump
370dumps the PDU in a human readable form by calling
371.Fn snmp_printf .
372.Pp
373The function
|
| 374.Fn snmp_passwd_to_keys
375calculates a binary private authentication key corresponding to a plain text human
376readable password string. The calculated key is placed in the
377.Fa auth_key
378field of the
379.Fa user .
380.Pp
381The function
382.Fn snmp_get_local_keys
383calculates a localazied authentication and privacy keys for a specified SNMPv3
384engine. The calculateds keys are placed in the
385.Fa auth_key
386and
387.Fa priv_key
388fields of the
389.Fa user .
390.Pp
391The function
392.Fn snmp_calc_keychange
393calculates a binary key change octet string based on the contents of an old and
394a new binary localized key. The rezult is placed in the buffer pointer to by
395.Fa keychange
396and may be used by an SNMPv3 user who wishes to change his/her password
397or localized key.
398.Pp
399The function
|
235.Fn TRUTH_MK
236takes a C truth value (zero or non-zero) and makes an SNMP truth value (2 or 1).
237The function
238.Fn TRUTH_GET
239takes an SNMP truth value and makes a C truth value (0 or 1).
240The function
241.Fn TRUTH_OK
242checks, whether its argument is a legal SNMP truth value.
243.Sh DIAGNOSTICS
244When an error occurs in any of the function the function pointed to
245by the global pointer
246.Bd -literal -offset indent
247extern void (*snmp_error)(const char *, ...);
248.Ed
249.Pp
250with a
251.Xr printf 3
252style format string.
253There is a default error handler in the library that prints a message
254starting with
255.Sq SNMP:
256followed by the error message to standard error.
257.Pp
258The function pointed to by
259.Bd -literal -offset indent
260extern void (*snmp_printf)(const char *, ...);
261.Ed
262.Pp
263is called by the
264.Fn snmp_pdu_dump
265function.
266The default handler is
267.Xr printf 3 .
268.Sh ERRORS
269.Fn snmp_pdu_decode
270will return one of the following return codes:
271.Bl -tag -width Er
272.It Bq Er SNMP_CODE_OK
273Success.
274.It Bq Er SNMP_CODE_FAILED
275The ASN.1 coding was wrong.
276.It Bq Er SNMP_CODE_BADLEN
277A variable binding value had a wrong length field.
278.It Bq Er SNMP_CODE_OORANGE
279A variable binding value was out of the allowed range.
280.It Bq Er SNMP_CODE_BADVERS
281The PDU is of an unsupported version.
282.It Bq Er SNMP_CODE_BADENQ
283There was an ASN.1 value with an unsupported tag.
| 400.Fn TRUTH_MK
401takes a C truth value (zero or non-zero) and makes an SNMP truth value (2 or 1).
402The function
403.Fn TRUTH_GET
404takes an SNMP truth value and makes a C truth value (0 or 1).
405The function
406.Fn TRUTH_OK
407checks, whether its argument is a legal SNMP truth value.
408.Sh DIAGNOSTICS
409When an error occurs in any of the function the function pointed to
410by the global pointer
411.Bd -literal -offset indent
412extern void (*snmp_error)(const char *, ...);
413.Ed
414.Pp
415with a
416.Xr printf 3
417style format string.
418There is a default error handler in the library that prints a message
419starting with
420.Sq SNMP:
421followed by the error message to standard error.
422.Pp
423The function pointed to by
424.Bd -literal -offset indent
425extern void (*snmp_printf)(const char *, ...);
426.Ed
427.Pp
428is called by the
429.Fn snmp_pdu_dump
430function.
431The default handler is
432.Xr printf 3 .
433.Sh ERRORS
434.Fn snmp_pdu_decode
435will return one of the following return codes:
436.Bl -tag -width Er
437.It Bq Er SNMP_CODE_OK
438Success.
439.It Bq Er SNMP_CODE_FAILED
440The ASN.1 coding was wrong.
441.It Bq Er SNMP_CODE_BADLEN
442A variable binding value had a wrong length field.
443.It Bq Er SNMP_CODE_OORANGE
444A variable binding value was out of the allowed range.
445.It Bq Er SNMP_CODE_BADVERS
446The PDU is of an unsupported version.
447.It Bq Er SNMP_CODE_BADENQ
448There was an ASN.1 value with an unsupported tag.
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| 449.It Bq Er SNMP_CODE_BADSECLEVEL
450The requested securityLevel contained in the PDU is not supported.
451.It Bq Er SNMP_CODE_BADDIGEST
452The PDU authentication parameter received in the PDU did not match the
453calculated message digest.
454.It Bq Er SNMP_CODE_EDECRYPT
455Error occured while trying to decrypt the PDU.
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284.El
285.Pp
286.Fn snmp_pdu_encode
287will return one of the following return codes:
288.Bl -tag -width Er
289.It Bq Er SNMP_CODE_OK
290Success.
291.It Bq Er SNMP_CODE_FAILED
292Encoding failed.
293.El
294.Sh SEE ALSO
295.Xr gensnmptree 1 ,
296.Xr bsnmpd 1 ,
297.Xr bsnmpagent 3 ,
298.Xr bsnmpclient 3 ,
299.Xr bsnmplib 3
| 456.El
457.Pp
458.Fn snmp_pdu_encode
459will return one of the following return codes:
460.Bl -tag -width Er
461.It Bq Er SNMP_CODE_OK
462Success.
463.It Bq Er SNMP_CODE_FAILED
464Encoding failed.
465.El
466.Sh SEE ALSO
467.Xr gensnmptree 1 ,
468.Xr bsnmpd 1 ,
469.Xr bsnmpagent 3 ,
470.Xr bsnmpclient 3 ,
471.Xr bsnmplib 3
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| 472.Sh CAVEAT
473The SNMPv3 message digests, encryption and decryption, and key routines use
474the cryptographic functions from
475.Xr crypto 3 .
476The library may optionally be built without references to the
477.Xr crypto 3
478library. In such case only plain text SNMPv3 PDUs without message digests
479may be proccessed correctly.
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300.Sh STANDARDS
301This implementation conforms to the applicable IETF RFCs and ITU-T
302recommendations.
303.Sh AUTHORS
| 480.Sh STANDARDS
481This implementation conforms to the applicable IETF RFCs and ITU-T
482recommendations.
483.Sh AUTHORS
|
| 484The Begemot SNMP library was originally written by
|
304.An Hartmut Brandt Aq harti@FreeBSD.org
| 485.An Hartmut Brandt Aq harti@FreeBSD.org
|
| 486.Pp
487.An Shteryana Shopova Aq syrinx@FreeBSD.org
488added support for the SNMPv3 message proccessing and User-Based
489Security model message authentication and privacy.
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| |