SSL_CTX_set_cert_verify_callback - set peer certificate
void SSL_CTX_set_cert_verify_callback(SSL_CTX *ctx, int (*callback)(),
SSL_CTX_set_cert_verify_callback() sets the verification
callback function for ctx. SSL objects, that are created
from ctx inherit the setting valid at the time, SSL_new(3)
is called. arg is currently ignored.
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 callback is specified via
SSL_CTX_set_cert_verify_callback(), the supplied callback
function is called instead. By setting callback to NULL,
the default behaviour is restored.
When the verification must be performed, callback will be
called with the argument callback(X509_STORE_CTX
*x509_store_ctx). The arguments arg that can be specified
when setting callback are currently ignored.
callback should return 1 to indicate verification success
and 0 to indicate verification failure. If SSL_VERIFY_PEER
is set and 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
error member of x509_store_ctx, so that the calling application
will be informed about the detailed result of the
Within x509_store_ctx, callback has access to the ver-
ify_callback function set using SSL_CTX_set_verify(3).
Do not mix the verification callback described in this
function with the verify_callback function called during
the verification process. The latter is set using the
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
It is possible to specify arguments to be passed to the
verification callback. Currently they are however not
passed but ignored.
The callback function is not specified via a prototype, so
that no type checking takes place.
SSL_CTX_set_cert_verify_callback() does not provide diagnostic
ssl(3), SSL_CTX_set_verify(3), SSL_get_verify_result(3),
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