shall be specified, the NULL pointer can be used for B<verify_callback>. In
this case last B<verify_callback> set specifically for this B<ssl> remains. If
no special B<callback> was set before, the default callback for the underlying
-B<ctx> is used, that was valid at the the time B<ssl> was created with
+B<ctx> is used, that was valid at the time B<ssl> was created with
L<SSL_new(3)|SSL_new(3)>.
SSL_CTX_set_verify_depth() sets the maximum B<depth> for the certificate chain
B<Server mode:> the server sends a client certificate request to the client.
The certificate returned (if any) is checked. If the verification process
-fails as indicated by B<verify_callback>, the TLS/SSL handshake is
+fails, the TLS/SSL handshake is
immediately terminated with an alert message containing the reason for
the verification failure.
The behaviour can be controlled by the additional
SSL_VERIFY_FAIL_IF_NO_PEER_CERT and SSL_VERIFY_CLIENT_ONCE flags.
B<Client mode:> the server certificate is verified. If the verification process
-fails as indicated by B<verify_callback>, the TLS/SSL handshake is
+fails, the TLS/SSL handshake is
immediately terminated with an alert message containing the reason for
the verification failure. If no server certificate is sent, because an
anonymous cipher is used, SSL_VERIFY_PEER is ignored.
Exactly one of the B<mode> flags SSL_VERIFY_NONE and SSL_VERIFY_PEER must be
set at any time.
+The actual verification procedure is performed either using the built-in
+verification procedure or using another application provided verification
+function set with
+L<SSL_CTX_set_cert_verify_callback(3)|SSL_CTX_set_cert_verify_callback(3)>.
+The following descriptions apply in the case of the built-in procedure. An
+application provided procedure also has access to the verify depth information
+and the verify_callback() function, but the way this information is used
+may be different.
+
SSL_CTX_set_verify_depth() and SSL_set_verify_depth() set the limit up
to which depth certificates in a chain are used during the verification
procedure. If the certificate chain is longer than allowed, the certificates
SSL_VERIFY_PEER is set, a verification failure alert is sent to the peer and
the TLS/SSL handshake is terminated. If B<verify_callback> returns 1,
the verification process is continued. If B<verify_callback> always returns
-1, the TLS/SSL handshake will never be terminated because of this application
-experiencing a verification failure. The calling process can however
-retrieve the error code of the last verification error using
+1, the TLS/SSL handshake will not be terminated with respect to verification
+failures and the connection will be established. The calling process can
+however retrieve the error code of the last verification error using
L<SSL_get_verify_result(3)|SSL_get_verify_result(3)> or by maintaining its
own error storage managed by B<verify_callback>.
* At this point, err contains the last verification error. We can use
* it for something special
*/
- if (!preverify_ok && (err == X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT)
+ if (!preverify_ok && (err == X509_V_ERR_UNABLE_TO_GET_ISSUER_CERT))
{
X509_NAME_oneline(X509_get_issuer_name(ctx->current_cert), buf, 256);
printf("issuer= %s\n", buf);
L<SSL_get_verify_result(3)|SSL_get_verify_result(3)>,
L<SSL_CTX_load_verify_locations(3)|SSL_CTX_load_verify_locations(3)>,
L<SSL_get_peer_certificate(3)|SSL_get_peer_certificate(3)>,
+L<SSL_CTX_set_cert_verify_callback(3)|SSL_CTX_set_cert_verify_callback(3)>,
L<SSL_get_ex_data_X509_STORE_CTX_idx(3)|SSL_get_ex_data_X509_STORE_CTX_idx(3)>,
L<SSL_get_ex_new_index(3)|SSL_get_ex_new_index(3)>