75 lines
2.8 KiB
Text
75 lines
2.8 KiB
Text
=pod
|
|
|
|
=head1 NAME
|
|
|
|
SSL_CTX_set_cert_verify_callback - set peer certificate verification procedure
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/ssl.h>
|
|
|
|
void SSL_CTX_set_cert_verify_callback(SSL_CTX *ctx, int (*callback)(X509_STORE_CTX *,void *), void *arg);
|
|
|
|
=head1 DESCRIPTION
|
|
|
|
SSL_CTX_set_cert_verify_callback() sets the verification callback function for
|
|
I<ctx>. SSL objects that are created from I<ctx> inherit the setting valid at
|
|
the time when L<SSL_new(3)|SSL_new(3)> is called.
|
|
|
|
=head1 NOTES
|
|
|
|
Whenever a certificate is verified during a SSL/TLS handshake, a verification
|
|
function is called. If the application does not explicitly specify a
|
|
verification callback function, the built-in verification function is used.
|
|
If a verification callback I<callback> is specified via
|
|
SSL_CTX_set_cert_verify_callback(), the supplied callback function is called
|
|
instead. By setting I<callback> to NULL, the default behaviour is restored.
|
|
|
|
When the verification must be performed, I<callback> will be called with
|
|
the arguments callback(X509_STORE_CTX *x509_store_ctx, void *arg). The
|
|
argument I<arg> is specified by the application when setting I<callback>.
|
|
|
|
I<callback> should return 1 to indicate verification success and 0 to
|
|
indicate verification failure. If SSL_VERIFY_PEER is set and I<callback>
|
|
returns 0, the handshake will fail. As the verification procedure may
|
|
allow to continue the connection in case of failure (by always returning 1)
|
|
the verification result must be set in any case using the B<error>
|
|
member of I<x509_store_ctx> so that the calling application will be informed
|
|
about the detailed result of the verification procedure!
|
|
|
|
Within I<x509_store_ctx>, I<callback> has access to the I<verify_callback>
|
|
function set using L<SSL_CTX_set_verify(3)|SSL_CTX_set_verify(3)>.
|
|
|
|
=head1 WARNINGS
|
|
|
|
Do not mix the verification callback described in this function with the
|
|
B<verify_callback> function called during the verification process. The
|
|
latter is set using the L<SSL_CTX_set_verify(3)|SSL_CTX_set_verify(3)>
|
|
family of functions.
|
|
|
|
Providing a complete verification procedure including certificate purpose
|
|
settings etc is a complex task. The built-in procedure is quite powerful
|
|
and in most cases it should be sufficient to modify its behaviour using
|
|
the B<verify_callback> function.
|
|
|
|
=head1 BUGS
|
|
|
|
=head1 RETURN VALUES
|
|
|
|
SSL_CTX_set_cert_verify_callback() does not provide diagnostic information.
|
|
|
|
=head1 SEE ALSO
|
|
|
|
L<ssl(3)|ssl(3)>, L<SSL_CTX_set_verify(3)|SSL_CTX_set_verify(3)>,
|
|
L<SSL_get_verify_result(3)|SSL_get_verify_result(3)>,
|
|
L<SSL_CTX_load_verify_locations(3)|SSL_CTX_load_verify_locations(3)>
|
|
|
|
=head1 HISTORY
|
|
|
|
Previous to OpenSSL 0.9.7, the I<arg> argument to B<SSL_CTX_set_cert_verify_callback>
|
|
was ignored, and I<callback> was called simply as
|
|
int (*callback)(X509_STORE_CTX *)
|
|
To compile software written for previous versions of OpenSSL, a dummy
|
|
argument will have to be added to I<callback>.
|
|
|
|
=cut
|