Server callback that selects an ALPN protocol from the client's offer.
Declared in <openssl/ssl.h>
typedef int(* SSL_CTX_alpn_select_cb_func)(SSL*, unsigned char const**, unsigned char*, unsigned char const*, unsigned int, void*);SSL_TLSEXT_ERR_OK to accept, SSL_TLSEXT_ERR_NOACK to skip ALPN, or SSL_TLSEXT_ERR_ALERT_FATAL to abort.
| Name | Description |
|---|---|
| ssl | SSL connection negotiating ALPN. |
| out | On success, set to the selected protocol (may point into in). |
| outlen | Receives the length of the selected protocol. |
| in | Client-offered protocols in wire list format. |
| inlen | Length of in in bytes. |
| arg | User argument registered with SSL_CTX_set_alpn_select_cb. |