[gnutls-devel] GnuTLS | tls1.3: server returns early on handshake when no cert is provided by client (!711)

[Development of GNU's TLS library]

Daiki Ueno commented on a discussion on lib/handshake-tls13.c:

> +	_gnutls_write_uint24(session->security_parameters.prf->output_size, finished+1);
> +
> +	ret = _gnutls_buffer_append_data(&session->internals.handshake_hash_buffer, finished,
> +					 TLS_HANDSHAKE_HEADER_SIZE+session->security_parameters.prf->output_size);
> +	if (ret < 0)
> +		return gnutls_assert_val(ret);
> +
> +	ret = _tls13_derive_secret(session, RMS_MASTER_LABEL, sizeof(RMS_MASTER_LABEL)-1,
> +				   session->internals.handshake_hash_buffer.data,
> +				   session->internals.handshake_hash_buffer.length,
> +				   session->key.proto.tls13.temp_secret,
> +				   session->key.proto.tls13.ap_rms);
> +	if (ret < 0)
> +		return gnutls_assert_val(ret);
> +
> +	session->internals.handshake_hash_buffer.length = spos;

In that case, that would be fine.

By the way, couldn't this be written like the following to share some code with `generate_rms_keys()`?
```c
spos = session->internals.handshake_hash_buffer.length;
ret = _gnutls_buffer_append_data(&session->internals.handshake_hash_buffer, ...);
session->internals.handshake_hash_buffer_client_finished_len = session->internals.handshake_hash_buffer.length;
session->internals.handshake_hash_buffer.length = spos;
return generate_rms_keys(session);
```

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