static gboolean irssi_ssl_verify_hostname(X509 *cert, const char *hostname)
{
	int gen_index, gen_count;
	gboolean matched = FALSE, has_dns_name = FALSE;
	const char *cert_dns_name;
	char *cert_subject_cn;
	const GENERAL_NAME *gn;
	STACK_OF(GENERAL_NAME) * gens;

	/* Verify the dNSName(s) in the peer certificate against the hostname. */
	gens = X509_get_ext_d2i(cert, NID_subject_alt_name, 0, 0);
	if (gens) {
		gen_count = sk_GENERAL_NAME_num(gens);
		for (gen_index = 0; gen_index < gen_count && !matched; ++gen_index) {
			gn = sk_GENERAL_NAME_value(gens, gen_index);
			if (gn->type != GEN_DNS)
				continue;

			/* Even if we have an invalid DNS name, we still ultimately
			   ignore the CommonName, because subjectAltName:DNS is
			   present (though malformed). */
			has_dns_name = TRUE;
			cert_dns_name = tls_dns_name(gn);
			if (cert_dns_name && *cert_dns_name) {
				matched = match_hostname(cert_dns_name, hostname);
			}
    	}

	    /* Free stack *and* member GENERAL_NAME objects */
	    sk_GENERAL_NAME_pop_free(gens, GENERAL_NAME_free);
	}

	if (has_dns_name) {
		if (! matched) {
			/* The CommonName in the issuer DN is obsolete when SubjectAltName is available. */
			g_warning("None of the Subject Alt Names in the certificate match hostname '%s'", hostname);
		}
		return matched;
	} else { /* No subjectAltNames, look at CommonName */
		cert_subject_cn = tls_text_name(X509_get_subject_name(cert), NID_commonName);
	    if (cert_subject_cn && *cert_subject_cn) {
	    	matched = match_hostname(cert_subject_cn, hostname);
	    	if (! matched) {
				g_warning("SSL certificate common name '%s' doesn't match host name '%s'", cert_subject_cn, hostname);
	    	}
	    } else {
	    	g_warning("No subjectAltNames and no valid common name in certificate");
	    }
	    free(cert_subject_cn);
	}

	return matched;
}
The product receives input or data, but it does
        not validate or incorrectly validates that the input has the
        properties that are required to process the data safely and
        correctly.