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Diffstat (limited to 'doc/ssl')
-rw-r--r-- | doc/ssl/SSL_CTX_set_cert_cb.pod | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/doc/ssl/SSL_CTX_set_cert_cb.pod b/doc/ssl/SSL_CTX_set_cert_cb.pod new file mode 100644 index 0000000000..98bd2f1e58 --- /dev/null +++ b/doc/ssl/SSL_CTX_set_cert_cb.pod @@ -0,0 +1,68 @@ +=pod + +=head1 NAME + +SSL_CTX_set_cert_cb, SSL_set_cert_cb - handle certificate callback function + +=head1 SYNOPSIS + + #include <openssl/ssl.h> + + void SSL_CTX_set_cert_cb(SSL_CTX *c, int (*cert_cb)(SSL *ssl, void *arg), void *arg); + void SSL_set_cert_cb(SSL *s, int (*cert_cb)(SSL *ssl, void *arg), void *arg); + + int (*cert_cb)(SSL *ssl, void *arg); + +=head1 DESCRIPTION + +SSL_CTX_set_cert_cb() and SSL_set_cert_cb() sets the B<cert_cb()> callback, +B<arg> value is pointer which is passed to the application callback. + +When B<cert_cb()> is NULL, no callback function is used. + +cert_cb() is the application defined callback. It is called before a +certificate will be used by a client or server. The callback can then inspect +the passed B<ssl> structure and set or clear any appropriate certificates. If +the callback is successful it B<MUST> return 1 even if no certificates have +been set. A zero is returned on error which will abort the handshake with a +fatal internal error alert. A negative return value will suspend the handshake +and the handshake function will return immediatly. +L<SSL_get_error(3)|SSL_get_error(3)> will return SSL_ERROR_WANT_X509_LOOKUP to +indicate, that the handshake was suspended. The next call to the handshake +function will again lead to the call of cert_cb(). It is the job of the +cert_cb() to store information about the state of the last call, +if required to continue. + +=head1 NOTES + +An application will typically call SSL_use_certificate() and +SSL_use_PrivateKey() to set the end entity certificate and private key. +It can add intermediate and optionally the root CA certificates using +SSL_add1_chain_cert(). + +It might also call SSL_certs_clear() to delete any certificates associated +with the B<SSL> object. + +The certificate callback functionality supercedes the (largely broken) +functionality provided by the old client certificate callback interface. +It is B<always> called even is a certificate is already set so the callback +can modify or delete the existing certificate. + +A more advanced callback might examine the handshake parameters and set +whatever chain is appropriate. For example a legacy client supporting only +TLS v1.0 might receive a certificate chain signed using SHA1 whereas a +TLS v1.2 client which advertises support for SHA256 could receive a chain +using SHA256. + +Normal server sanity checks are performed on any certificates set +by the callback. So if an EC chain is set for a curve the client does not +support it will B<not> be used. + +=head1 SEE ALSO + +L<ssl(3)|ssl(3)>, L<SSL_use_certificate(3)|SSL_use_certificate(3)>, +L<SSL_add1_chain_cert(3)|SSL_add1_chain_cert(3)>, +L<SSL_get_client_CA_list(3)|SSL_get_client_CA_list(3)>, +L<SSL_clear(3)|SSL_clear(3)>, L<SSL_free(3)|SSL_free(3)> + +=cut |