1LBER_ENCODE(3) Library Functions Manual LBER_ENCODE(3)
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6 ber_alloc_t, ber_flush, ber_flush2, ber_printf, ber_put_int,
7 ber_put_enum, ber_put_ostring, ber_put_string, ber_put_null,
8 ber_put_boolean, ber_put_bitstring, ber_start_seq, ber_start_set,
9 ber_put_seq, ber_put_set - OpenLDAP LBER simplified Basic Encoding
10 Rules library routines for 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_flush2(Sockbuf *sb, BerElement *ber, int freeit);
23 int ber_printf(BerElement *ber, const char *fmt, ...);
25 int ber_put_int(BerElement *ber, ber_int_t num, ber_tag_t tag);
27 int ber_put_enum(BerElement *ber, ber_int_t num, ber_tag_t tag);
29 int ber_put_ostring(BerElement *ber, const char *str, ber_len_t len,
31 ber_tag_t tag);
32 int ber_put_string(BerElement *ber, const char *str, ber_tag_t tag);
34 int ber_put_null(BerElement *ber, ber_tag_t tag);
36 int ber_put_boolean(BerElement *ber, ber_int_t bool, ber_tag_t tag);
38 int ber_put_bitstring(BerElement *ber, const char *str, ber_len_t blen,
40 ber_tag_t tag);
41 int ber_start_seq(BerElement *ber, ber_tag_t tag);
43 int ber_start_set(BerElement *ber, ber_tag_t tag);
45 int ber_put_seq(BerElement *ber);
47 int ber_put_set(BerElement *ber);
49
51 These routines provide a subroutine interface to a simplified implemen‐
52 tation of the Basic Encoding Rules of ASN.1. The version of BER these
53 routines support is the one defined for the LDAP protocol. The encod‐
54 ing rules are the same as BER, except that only definite form lengths
55 are used, and bitstrings and octet strings are always encoded in primi‐
56 tive form. This man page describes the encoding routines in the lber
57 library. See lber-decode(3) for details on the corresponding decoding
58 routines. Consult lber-types(3) for information about types, alloca‐
59 tors, and deallocators.
60 Normally, the only routines that need to be called by an application
62 are ber_alloc_t() to allocate a BER element for encoding, ber_printf()
63 to do the actual encoding, and ber_flush2() to actually write the ele‐
64 ment. The other routines are provided for those applications that need
65 more control than ber_printf() provides. In general, these routines
66 return the length of the element encoded, or -1 if an error occurred.
67 The ber_alloc_t() routine is used to allocate a new BER element. It
69 should be called with an argument of LBER_USE_DER.
70 The ber_flush2() routine is used to actually write the element to a
72 socket (or file) descriptor, once it has been fully encoded (using
73 ber_printf() and friends). See lber-sockbuf(3) for more details on the
74 Sockbuf implementation of the sb parameter. If the freeit parameter is
75 non-zero, the supplied ber will be freed. If LBER_FLUSH_FREE_ON_SUC‐
76 CESS is used, the ber is only freed when successfully flushed, other‐
77 wise it is left intact; if LBER_FLUSH_FREE_ON_ERROR is used, the ber is
78 only freed when an error occurs, otherwise it is left intact; if
79 LBER_FLUSH_FREE_ALWAYS is used, the ber is freed anyway. This function
80 differs from the original ber_flush(3) function, whose behavior corre‐
81 sponds to that indicated for LBER_FLUSH_FREE_ON_SUCCESS. Note that in
82 the future, the behavior of ber_flush(3) with freeit non-zero might
83 change into that of ber_flush2(3) with freeit set to
84 LBER_FLUSH_FREE_ALWAYS.
85 The ber_printf() routine is used to encode a BER element in much the
87 same way that sprintf(3) works. One important difference, though, is
88 that some state information is kept with the ber parameter so that mul‐
89 tiple calls can be made to ber_printf() to append things to the end of
90 the BER element. Ber_printf() writes to ber, a pointer to a BerElement
91 such as returned by ber_alloc_t(). It interprets and formats its argu‐
92 ments according to the format string fmt. The format string can con‐
93 tain the following characters:
94 b Boolean. An ber_int_t parameter should be supplied. A bool‐
96 ean element is output.
97 e Enumeration. An ber_int_t parameter should be supplied. An
99 enumeration element is output.
100 i Integer. An ber_int_t parameter should be supplied. An in‐
102 teger element is output.
103 B Bitstring. A char * pointer to the start of the bitstring is
105 supplied, followed by the number of bits in the bitstring. A
106 bitstring element is output.
107 n Null. No parameter is required. A null element is output.
109 o Octet string. A char * is supplied, followed by the length
111 of the string pointed to. An octet string element is output.
112 O Octet string. A struct berval * is supplied. An octet
114 string element is output.
115 s Octet string. A null-terminated string is supplied. An
117 octet string element is output, not including the trailing
118 NULL octet.
119 t Tag. A ber_tag_t specifying the tag to give the next element
121 is provided. This works across calls.
122 v Several octet strings. A null-terminated array of char *'s
124 is supplied. Note that a construct like '{v}' is required to
125 get an actual SEQUENCE OF octet strings.
126 V Several octet strings. A null-terminated array of struct
128 berval *'s is supplied. Note that a construct like '{V}' is
129 required to get an actual SEQUENCE OF octet strings.
130 W Several octet strings. An array of struct berval's is sup‐
132 plied. The array is terminated by a struct berval with a
133 NULL bv_val. Note that a construct like '{W}' is required to
134 get an actual SEQUENCE OF octet strings.
135 { Begin sequence. No parameter is required.
137 } End sequence. No parameter is required.
139 [ Begin set. No parameter is required.
141 ] End set. No parameter is required.
143 The ber_put_int() routine writes the integer element num to the BER el‐
145 ement ber.
146 The ber_put_enum() routine writes the enumeration element num to the
148 BER element ber.
149 The ber_put_boolean() routine writes the boolean value given by bool to
151 the BER element.
152 The ber_put_bitstring() routine writes blen bits starting at str as a
154 bitstring value to the given BER element. Note that blen is the length
155 in bits of the bitstring.
156 The ber_put_ostring() routine writes len bytes starting at str to the
158 BER element as an octet string.
159 The ber_put_string() routine writes the null-terminated string (minus
161 the terminating ' ') to the BER element as an octet string.
162 The ber_put_null() routine writes a NULL element to the BER element.
164 The ber_start_seq() routine is used to start a sequence in the BER ele‐
166 ment. The ber_start_set() routine works similarly. The end of the se‐
167 quence or set is marked by the nearest matching call to ber_put_seq()
168 or ber_put_set(), respectively.
169
171 Assuming the following variable declarations, and that the variables
172 have been assigned appropriately, an lber encoding of the following
173 ASN.1 object:
174 AlmostASearchRequest := SEQUENCE {
176 baseObject DistinguishedName,
177 scope ENUMERATED {
178 baseObject (0),
179 singleLevel (1),
180 wholeSubtree (2)
181 },
182 derefAliases ENUMERATED {
183 neverDerefaliases (0),
184 derefInSearching (1),
185 derefFindingBaseObj (2),
186 alwaysDerefAliases (3)
187 },
188 sizelimit INTEGER (0 .. 65535),
189 timelimit INTEGER (0 .. 65535),
190 attrsOnly BOOLEAN,
191 attributes SEQUENCE OF AttributeType
192 }
193 can be achieved like so:
195 int rc;
197 ber_int_t scope, ali, size, time, attrsonly;
198 char *dn, **attrs;
199 BerElement *ber;
200 /* ... fill in values ... */
202 ber = ber_alloc_t( LBER_USE_DER );
204 if ( ber == NULL ) {
206 /* error */
207 }
208 rc = ber_printf( ber, "{siiiib{v}}", dn, scope, ali,
210 size, time, attrsonly, attrs );
211 if( rc == -1 ) {
213 /* error */
214 } else {
215 /* success */
216 }
217
219 If an error occurs during encoding, generally these routines return -1.
220
222 The return values for all of these functions are declared in the
223 <lber.h> header file.
224
226 lber-decode(3), lber-memory(3), lber-sockbuf(3), lber-types(3)
227
229 OpenLDAP Software is developed and maintained by The OpenLDAP Project
230 <http://www.openldap.org/>. OpenLDAP Software is derived from the Uni‐
231 versity of Michigan LDAP 3.3 Release.
232OpenLDAP 2.4.57 2021/01/18 LBER_ENCODE(3)