.\" $OpenBSD: OBJ_nid2obj.3,v 1.18 2021/12/18 17:47:45 schwarze Exp $ .\" full merge up to: OpenSSL c264592d May 14 11:28:00 2006 +0000 .\" selective merge up to: OpenSSL 35fd9953 May 28 14:49:38 2019 +0200 .\" .\" This file is a derived work. .\" The changes are covered by the following Copyright and license: .\" .\" Copyright (c) 2017, 2021 Ingo Schwarze .\" .\" Permission to use, copy, modify, and distribute this software for any .\" purpose with or without fee is hereby granted, provided that the above .\" copyright notice and this permission notice appear in all copies. .\" .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF .\" MERCHANTABILITY AND FITNESS. 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IN NO EVENT SHALL THE OpenSSL PROJECT OR .\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, .\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; .\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, .\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED .\" OF THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd $Mdocdate: December 18 2021 $ .Dt OBJ_NID2OBJ 3 .Os .Sh NAME .Nm OBJ_nid2obj , .Nm OBJ_nid2ln , .Nm OBJ_nid2sn , .Nm OBJ_obj2nid , .Nm OBJ_ln2nid , .Nm OBJ_sn2nid , .Nm OBJ_txt2nid , .Nm OBJ_txt2obj , .Nm OBJ_obj2txt , .Nm OBJ_cmp , .Nm OBJ_dup , .Nm i2t_ASN1_OBJECT , .Nm i2a_ASN1_OBJECT .Nd inspect and create ASN.1 object identifiers .Sh SYNOPSIS .In openssl/objects.h .Ft ASN1_OBJECT * .Fo OBJ_nid2obj .Fa "int n" .Fc .Ft const char * .Fo OBJ_nid2ln .Fa "int n" .Fc .Ft const char * .Fo OBJ_nid2sn .Fa "int n" .Fc .Ft int .Fo OBJ_obj2nid .Fa "const ASN1_OBJECT *o" .Fc .Ft int .Fo OBJ_ln2nid .Fa "const char *ln" .Fc .Ft int .Fo OBJ_sn2nid .Fa "const char *sn" .Fc .Ft int .Fo OBJ_txt2nid .Fa "const char *s" .Fc .Ft ASN1_OBJECT * .Fo OBJ_txt2obj .Fa "const char *s" .Fa "int no_name" .Fc .Ft int .Fo OBJ_obj2txt .Fa "char *buf" .Fa "int buf_len" .Fa "const ASN1_OBJECT *a" .Fa "int no_name" .Fc .Ft int .Fo OBJ_cmp .Fa "const ASN1_OBJECT *a" .Fa "const ASN1_OBJECT *b" .Fc .Ft ASN1_OBJECT * .Fo OBJ_dup .Fa "const ASN1_OBJECT *o" .Fc .In openssl/asn1.h .Ft int .Fo i2t_ASN1_OBJECT .Fa "char *buf" .Fa "int buf_len" .Fa "const ASN1_OBJECT *a" .Fc .Ft int .Fo i2a_ASN1_OBJECT .Fa "BIO *out_bio" .Fa "const ASN1_OBJECT *a" .Fc .Sh DESCRIPTION The ASN.1 object utility functions process .Vt ASN1_OBJECT structures which are a representation of the ASN.1 OBJECT IDENTIFIER (OID) type. For convenience, OIDs are usually represented in source code as numeric identifiers, or NIDs. OpenSSL has an internal table of OIDs that are generated when the library is built, and their corresponding NIDs are available as defined constants. For the functions below, application code should treat all returned values \(em OIDs, NIDs, or names \(em as constants. .Pp .Fn OBJ_nid2obj , .Fn OBJ_nid2ln , and .Fn OBJ_nid2sn convert the NID .Fa n to an .Vt ASN1_OBJECT structure, its long name, and its short name, respectively, or return .Dv NULL if an error occurred. .Pp .Fn OBJ_obj2nid , .Fn OBJ_ln2nid , and .Fn OBJ_sn2nid return the corresponding NID for the object .Fa o , the long name .Fa ln , or the short name .Fa sn , respectively, or .Dv NID_undef if an error occurred. .Pp .Fn OBJ_txt2nid returns the NID corresponding to text string .Fa s . .Fa s can be a long name, a short name, or the numerical representation of an object. .Pp .Fn OBJ_txt2obj converts the text string .Fa s into an .Vt ASN1_OBJECT structure. If .Fa no_name is 0 then long names and short names will be interpreted as well as numerical forms. If .Fa no_name is 1 only the numerical form is acceptable. .Pp .Fn OBJ_obj2txt converts the .Vt ASN1_OBJECT .Fa a into a textual representation. The representation is written as a NUL terminated string to .Fa buf . At most .Fa buf_len bytes are written, truncating the result if necessary. The total amount of space required is returned. If .Fa no_name is 0 and the object has a long or short name, then that will be used, otherwise the numerical form will be used. .Pp .Fn i2t_ASN1_OBJECT is the same as .Fn OBJ_obj2txt with .Fa no_name set to 0. .Pp .Fn i2a_ASN1_OBJECT writes a textual representation of .Fa a to .Fa out_bio using .Xr BIO_write 3 . It does not write a terminating NUL byte. If .Fa a is .Dv NULL or contains no data, it writes the 4-byte string .Qq NULL . If .Fn i2t_ASN1_OBJECT fails, .Fn i2a_ASN1_OBJECT writes the 9-byte string .Qq . Otherwise, it writes the string constructed with .Fn i2t_ASN1_OBJECT . .Pp .Fn OBJ_cmp compares .Fa a to .Fa b . If the two are identical, 0 is returned. .Pp .Fn OBJ_dup returns a deep copy of .Fa o if .Fa o is marked as dynamically allocated. The new object and all data contained in it is marked as dynamically allocated. If .Fa o is not marked as dynamically allocated, .Fn OBJ_dup just returns .Fa o itself. .Pp Objects can have a short name, a long name, and a numerical identifier (NID) associated with them. A standard set of objects is represented in an internal table. The appropriate values are defined in the header file .In openssl/objects.h . .Pp For example, the OID for commonName has the following definitions: .Bd -literal #define SN_commonName "CN" #define LN_commonName "commonName" #define NID_commonName 13 .Ed .Pp New objects can be added by calling .Xr OBJ_create 3 . .Pp Table objects have certain advantages over other objects: for example their NIDs can be used in a C language switch statement. They are also static constant structures which are shared: that is there is only a single constant structure for each table object. .Pp Objects which are not in the table have the NID value .Dv NID_undef . .Pp Objects do not need to be in the internal tables to be processed: the functions .Fn OBJ_txt2obj and .Fn OBJ_obj2txt can process the numerical form of an OID. .Sh RETURN VALUES .Fn OBJ_nid2obj , .Fn OBJ_txt2obj , and .Fn OBJ_dup return an .Vt ASN1_OBJECT object or .Dv NULL if an error occurs. .Pp .Fn OBJ_nid2ln and .Fn OBJ_nid2sn return a valid string or .Dv NULL on error. .Pp .Fn OBJ_obj2nid , .Fn OBJ_ln2nid , .Fn OBJ_sn2nid , and .Fn OBJ_txt2nid return a NID or .Dv NID_undef on error. .Pp .Fn OBJ_obj2txt and .Fn i2t_ASN1_OBJECT return the amount of space required in bytes, including the terminating NUL byte. .Pp .Fn i2a_ASN1_OBJECT returns the number of bytes written, even if .Fa a is invalid or contains invalid data, but a negative value if memory allocation or a write operation fails. .Pp .Fn OBJ_cmp returns 0 if the contents of .Fa a and .Fa b are identical, or non-zero otherwise. .Pp In some cases of failure of .Fn OBJ_nid2obj , .Fn OBJ_nid2ln , .Fn OBJ_nid2sn , .Fn OBJ_txt2nid , .Fn OBJ_txt2obj , .Fn OBJ_obj2txt , .Fn OBJ_dup , .Fn i2t_ASN1_OBJECT , and .Fn i2a_ASN1_OBJECT , the reason can be determined with .Xr ERR_get_error 3 . .Sh EXAMPLES Create an object for .Sy commonName : .Bd -literal -offset indent ASN1_OBJECT *o; o = OBJ_nid2obj(NID_commonName); .Ed .Pp Check if an object is .Sy commonName : .Bd -literal -offset indent if (OBJ_obj2nid(obj) == NID_commonName) /* Do something */ .Ed .Pp Create a new object directly: .Bd -literal -offset indent obj = OBJ_txt2obj("1.2.3.4", 1); .Ed .Sh SEE ALSO .Xr ASN1_OBJECT_new 3 , .Xr BIO_new 3 , .Xr d2i_ASN1_OBJECT 3 , .Xr OBJ_add_sigid 3 , .Xr OBJ_create 3 , .Xr OBJ_NAME_add 3 .Sh HISTORY .Fn OBJ_nid2obj , .Fn OBJ_nid2ln , .Fn OBJ_nid2sn , .Fn OBJ_obj2nid , .Fn OBJ_ln2nid , .Fn OBJ_sn2nid , .Fn OBJ_txt2nid , .Fn OBJ_cmp , and .Fn OBJ_dup first appeared in SSLeay 0.5.1. .Fn i2a_ASN1_OBJECT first appeared in SSLeay 0.6.0, and .Fn i2t_ASN1_OBJECT in SSLeay 0.9.0. All these functions have been available since .Ox 2.4 . .Pp .Fn OBJ_txt2obj first appeared in OpenSSL 0.9.2b. .Fn OBJ_obj2txt first appeared in OpenSSL 0.9.4. Both functions have been available since .Ox 2.6 . .Sh BUGS .Fn OBJ_obj2txt is awkward and messy to use: it doesn't follow the convention of other OpenSSL functions where the buffer can be set to .Dv NULL to determine the amount of data that should be written. Instead .Fa buf must point to a valid buffer and .Fa buf_len should be set to a positive value. A buffer length of 80 should be more than enough to handle any OID encountered in practice.