[#SSL_custom_ext_add_cb_ex]
= SSL_custom_ext_add_cb_ex
:mrdocs:

Callback that supplies the contents of a custom TLS extension being sent.

== Synopsis

Declared in `<openssl/ssl.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
typedef int(* SSL_custom_ext_add_cb_ex)(xref:SSL.adoc[SSL]*, unsigned int, unsigned int, unsigned char const**, size_t*, xref:X509.adoc[X509]*, size_t, int*, void*);
----

== Return Value

1 to include the extension, 0 to omit it, or ‐1 to abort with *`al.`

== Parameters

[cols="1,4"]
|===
| Name| Description
| *s*
| SSL connection constructing the extension.
| *ext_type*
| TLS extension type code.
| *context*
| Bitmask identifying the message and role (SSL_EXT_*).
| *out*
| Set to point at the extension payload bytes to send.
| *outlen*
| Receives the length of *`out.`
| *x*
| Certificate associated with this extension when relevant, or NULL.
| *chainidx*
| Index of `x` in the certificate chain when applicable.
| *al*
| Set to a TLS alert code on failure.
| *add_arg*
| User argument from SSL_CTX_add_custom_ext.
|===


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