int ssl_prepare_clienthello_tlsext(SSL *s)
	{

#ifdef TLSEXT_TYPE_opaque_prf_input
 	{
		int r = 1;
	
		if (s->ctx->tlsext_opaque_prf_input_callback != 0)
			{
			r = s->ctx->tlsext_opaque_prf_input_callback(s, NULL, 0, s->ctx->tlsext_opaque_prf_input_callback_arg);
			if (!r)
				return -1;
			}

		if (s->tlsext_opaque_prf_input != NULL)
			{
			if (s->s3->client_opaque_prf_input != NULL) /* shouldn't really happen */
				OPENSSL_free(s->s3->client_opaque_prf_input);

			if (s->tlsext_opaque_prf_input_len == 0)
				s->s3->client_opaque_prf_input = OPENSSL_malloc(1); /* dummy byte just to get non-NULL */
			else
				s->s3->client_opaque_prf_input = BUF_memdup(s->tlsext_opaque_prf_input, s->tlsext_opaque_prf_input_len);
			if (s->s3->client_opaque_prf_input == NULL)
				{
				SSLerr(SSL_F_SSL_PREPARE_CLIENTHELLO_TLSEXT,ERR_R_MALLOC_FAILURE);
				return -1;
				}
			s->s3->client_opaque_prf_input_len = s->tlsext_opaque_prf_input_len;
			}

		if (r == 2)
			/* at callback's request, insist on receiving an appropriate server opaque PRF input */
			s->s3->server_opaque_prf_input_len = s->tlsext_opaque_prf_input_len;
	}
#endif

	return 1;
	}

Unknown