Sortix 1.1dev nightly manual
This manual documents Sortix 1.1dev nightly, a development build that has not been officially released. You can instead view this document in the latest official manual.
SSL_CTX_SET_CERT_VERIFY_CALLBACK(3) | Library Functions Manual | SSL_CTX_SET_CERT_VERIFY_CALLBACK(3) |
NAME
SSL_CTX_set_cert_verify_callback
—
set peer certificate verification procedure
SYNOPSIS
#include
<openssl/ssl.h>
void
SSL_CTX_set_cert_verify_callback
(SSL_CTX
*ctx, int (*callback)(X509_STORE_CTX *, void
*), void *arg);
DESCRIPTION
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
when SSL_new(3) is
called.
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 arguments
callback
(X509_STORE_CTX
*x509_store_ctx, void *arg). The
argument arg is specified by the application
when setting callback.
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 the connection to continue 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 verification
procedure!
Within x509_store_ctx,
callback has access to the
verify_callback function set using
SSL_CTX_set_verify(3).
SEE ALSO
ssl(3), SSL_CTX_load_verify_locations(3), SSL_CTX_set_verify(3), SSL_get_verify_result(3)HISTORY
SSL_CTX_set_cert_verify_callback
() first
appeared in SSLeay 0.6.1 and has been available since OpenBSD
2.4.
Previous to OpenSSL 0.9.7, the arg argument to
SSL_CTX_set_cert_verify_callback
() was
ignored, and 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
callback.
CAVEATS
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 verify_callback function.BUGS
SSL_CTX_set_cert_verify_callback
() does not
provide diagnostic information.June 8, 2019 | Debian |