NPN client callback that selects a protocol from the server's list.
Declared in <openssl/ssl.h>
typedef int(* SSL_CTX_npn_select_cb_func)(SSL*, unsigned char**, unsigned char*, unsigned char const*, unsigned int, void*);SSL_TLSEXT_ERR_OK on success; other values abort the connection.
| Name | Description |
|---|---|
| s | SSL connection performing NPN. |
| out | On success, set to the selected protocol (may point into in). |
| outlen | Receives the length of the selected protocol name. |
| in | Server-advertised protocols in wire list format. |
| inlen | Length of in in bytes. |
| arg | User argument registered with SSL_CTX_set_next_proto_select_cb. |