1LBER_ENCODE(3) Library Functions Manual LBER_ENCODE(3)
2
6 ber_alloc_t, ber_flush, ber_printf, ber_put_int, ber_put_enum,
7 ber_put_ostring, ber_put_string, ber_put_null, ber_put_boolean,
8 ber_put_bitstring, ber_start_seq, ber_start_set, ber_put_seq,
9 ber_put_set - LBER simplified Basic Encoding Rules library routines for
10 encoding
11
13 OpenLDAP LBER (liblber, -llber)
14
16 #include <lber.h>
17 BerElement *ber_alloc_t(int options);
19 int ber_flush(Sockbuf *sb, BerElement *ber, int freeit);
21 int ber_printf(BerElement *ber, const char *fmt, ...);
23 int ber_put_int(BerElement *ber, ber_int_t num, ber_tag_t tag);
25 int ber_put_enum(BerElement *ber, ber_int_t num, ber_tag_t tag);
27 int ber_put_ostring(BerElement *ber, const char *str, ber_len_t len,
29 ber_tag_t tag);
30 int ber_put_string(BerElement *ber, const char *str, ber_tag_t tag);
32 int ber_put_null(BerElement *ber, ber_tag_t tag);
34 int ber_put_boolean(BerElement *ber, ber_int_t bool, ber_tag_t tag);
36 int ber_put_bitstring(BerElement *ber, const char *str, ber_len_t blen,
38 ber_tag_t tag);
39 int ber_start_seq(BerElement *ber, ber_tag_t tag);
41 int ber_start_set(BerElement *ber, ber_tag_t tag);
43 int ber_put_seq(BerElement *ber);
45 int ber_put_set(BerElement *ber);
47
49 These routines provide a subroutine interface to a simplified implemen‐
50 tation of the Basic Encoding Rules of ASN.1. The version of BER these
51 routines support is the one defined for the LDAP protocol. The encod‐
52 ing rules are the same as BER, except that only definite form lengths
53 are used, and bitstrings and octet strings are always encoded in primi‐
54 tive form. This man page describes the encoding routines in the lber
55 library. See lber-decode(3) for details on the corresponding decoding
56 routines. Consult lber-types(3) for information about types, alloca‐
57 tors, and deallocators.
58 Normally, the only routines that need to be called by an application
60 are ber_alloc_t() to allocate a BER element for encoding, ber_printf()
61 to do the actual encoding, and ber_flush() to actually write the ele‐
62 ment. The other routines are provided for those applications that need
63 more control than ber_printf() provides. In general, these routines
64 return the length of the element encoded, or -1 if an error occurred.
65 The ber_alloc_t() routine is used to allocate a new BER element. It
67 should be called with an argument of LBER_USE_DER.
68 The ber_flush() routine is used to actually write the element to a
70 socket (or file) descriptor, once it has been fully encoded (using
71 ber_printf() and friends). See lber-sockbuf(3) for more details on the
72 Sockbuf implementation of the sb parameter. If the freeit parameter is
73 non-zero, the supplied ber will be freed after its contents have been
74 flushed.
75 The ber_printf() routine is used to encode a BER element in much the
77 same way that sprintf(3) works. One important difference, though, is
78 that some state information is kept with the ber parameter so that mul‐
79 tiple calls can be made to ber_printf() to append things to the end of
80 the BER element. Ber_printf() writes to ber, a pointer to a BerElement
81 such as returned by ber_alloc_t(). It interprets and formats its argu‐
82 ments according to the format string fmt. The format string can con‐
83 tain the following characters:
84 b Boolean. An ber_int_t parameter should be supplied. A bool‐
86 ean element is output.
87 e Enumeration. An ber_int_t parameter should be supplied. An
89 enumeration element is output.
90 i Integer. An ber_int_t parameter should be supplied. An
92 integer element is output.
93 B Bitstring. A char * pointer to the start of the bitstring is
95 supplied, followed by the number of bits in the bitstring. A
96 bitstring element is output.
97 n Null. No parameter is required. A null element is output.
99 o Octet string. A char * is supplied, followed by the length
101 of the string pointed to. An octet string element is output.
102 O Octet string. A struct berval * is supplied. An octet
104 string element is output.
105 s Octet string. A null-terminated string is supplied. An
107 octet string element is output, not including the trailing
108 NULL octet.
109 t Tag. A ber_tag_t specifying the tag to give the next element
111 is provided. This works across calls.
112 v Several octet strings. A null-terminated array of char *'s
114 is supplied. Note that a construct like '{v}' is required to
115 get an actual SEQUENCE OF octet strings.
116 V Several octet strings. A null-terminated array of struct
118 berval *'s is supplied. Note that a construct like '{V}' is
119 required to get an actual SEQUENCE OF octet strings.
120 W Several octet strings. An array of struct berval's is sup‐
122 plied. The array is terminated by a struct berval with a
123 NULL bv_val. Note that a construct like '{W}' is required to
124 get an actual SEQUENCE OF octet strings.
125 { Begin sequence. No parameter is required.
127 } End sequence. No parameter is required.
129 [ Begin set. No parameter is required.
131 ] End set. No parameter is required.
133 The ber_put_int() routine writes the integer element num to the BER
135 element ber.
136 The ber_put_enum() routine writes the enumeration element num to the
138 BER element ber.
139 The ber_put_boolean() routine writes the boolean value given by bool to
141 the BER element.
142 The ber_put_bitstring() routine writes blen bits starting at str as a
144 bitstring value to the given BER element. Note that blen is the length
145 in bits of the bitstring.
146 The ber_put_ostring() routine writes len bytes starting at str to the
148 BER element as an octet string.
149 The ber_put_string() routine writes the null-terminated string (minus
151 the terminating ' ') to the BER element as an octet string.
152 The ber_put_null() routine writes a NULL element to the BER element.
154 The ber_start_seq() routine is used to start a sequence in the BER ele‐
156 ment. The ber_start_set() routine works similarly. The end of the
157 sequence or set is marked by the nearest matching call to ber_put_seq()
158 or ber_put_set(), respectively.
159
161 Assuming the following variable declarations, and that the variables
162 have been assigned appropriately, an lber encoding of the following
163 ASN.1 object:
164 AlmostASearchRequest := SEQUENCE {
166 baseObject DistinguishedName,
167 scope ENUMERATED {
168 baseObject (0),
169 singleLevel (1),
170 wholeSubtree (2)
171 },
172 derefAliases ENUMERATED {
173 neverDerefaliases (0),
174 derefInSearching (1),
175 derefFindingBaseObj (2),
176 alwaysDerefAliases (3)
177 },
178 sizelimit INTEGER (0 .. 65535),
179 timelimit INTEGER (0 .. 65535),
180 attrsOnly BOOLEAN,
181 attributes SEQUENCE OF AttributeType
182 }
183 can be achieved like so:
185 int rc;
187 ber_int_t scope, ali, size, time, attrsonly;
188 char *dn, **attrs;
189 BerElement *ber;
190 /* ... fill in values ... */
192 ber = ber_alloc_t( LBER_USE_DER );
194 if ( ber == NULL ) {
196 /* error */
197 }
198 rc = ber_printf( ber, "{siiiib{v}}", dn, scope, ali,
200 size, time, attrsonly, attrs );
201 if( rc == -1 ) {
203 /* error */
204 } else {
205 /* success */
206 }
207
209 If an error occurs during encoding, generally these routines return -1.
210
212 The return values for all of these functions are declared in the
213 <lber.h> header file.
214
216 lber-decode(3), lber-memory(3), lber-sockbuf(3), lber-types(3)
217
219 OpenLDAP is developed and maintained by The OpenLDAP Project
220 (http://www.openldap.org/). OpenLDAP is derived from University of
221 Michigan LDAP 3.3 Release.
222OpenLDAP 2.3.34 2007/2/16 LBER_ENCODE(3)