[#SSL_CTX_add_server_custom_ext]
= SSL_CTX_add_server_custom_ext
:mrdocs:

Register a custom TLS extension handler for the server role on an SSL context.

== Synopsis

Declared in `<openssl/ssl.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
int
SSL_CTX_add_server_custom_ext(
    xref:SSL_CTX.adoc[SSL_CTX]* ctx,
    unsigned int ext_type,
    xref:custom_ext_add_cb.adoc[custom_ext_add_cb] add_cb,
    xref:custom_ext_free_cb.adoc[custom_ext_free_cb] free_cb,
    void* add_arg,
    xref:custom_ext_parse_cb.adoc[custom_ext_parse_cb] parse_cb,
    void* parse_arg);
----

== Return Value

1 on success, or 0 on failure.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *ctx*
| Server SSL context that sends or receives the extension.
| *ext_type*
| Extension type code (must not collide with built‐in handlers).
| *add_cb*
| Callback that constructs extension data to send, or NULL.
| *free_cb*
| Callback that frees data produced by `add_cb,` or NULL.
| *add_arg*
| Opaque pointer passed to `add_cb` / `free_cb.`
| *parse_cb*
| Callback that parses a received extension, or NULL.
| *parse_arg*
| Opaque pointer passed to `parse_cb.`
|===


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