[#BIO_asn1_set_prefix]
= BIO_asn1_set_prefix
:mrdocs:

Install prefix encode/free callbacks on a BIO_f_asn1() filter BIO.

== Synopsis

Declared in `<openssl/bio.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
BIO_asn1_set_prefix(
    xref:BIO.adoc[BIO]* b,
    xref:asn1_ps_func.adoc[asn1_ps_func]* prefix,
    xref:asn1_ps_func.adoc[asn1_ps_func]* prefix_free);
----

== Return Value

1 on success, or 0 on failure.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *b*
| ASN.1 filter BIO to configure.
| *prefix*
| Callback that writes prefix octets before each ASN.1 item, or NULL.
| *prefix_free*
| Optional cleanup for prefix state, or NULL.
|===


[.small]#Created with https://www.mrdocs.com[MrDocs]#