NAME¶
CURLOPT_SSL_CTX_FUNCTION - openssl specific callback to do SSL magic
SYNOPSIS¶
#include <curl/curl.h>
CURLcode ssl_ctx_callback(CURL *curl, void *ssl_ctx, void *userptr);
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_CTX_FUNCTION,
ssl_ctx_callback);
DESCRIPTION¶
This option only works for libcurl powered by OpenSSL. If libcurl was built
against another SSL library, this functionality is absent.
Pass a pointer to your callback function, which should match the prototype shown
above.
This callback function gets called by libcurl just before the initialization of
a SSL connection after having processed all other SSL related options to give
a last chance to an application to modify the behaviour of openssl's ssl
initialization. The
sslctx parameter is actually a pointer to an
openssl
SSL_CTX. If an error is returned from the callback, no attempt
to establish a connection is made and the perform operation will return the
error code. Set the
userptr argument with the
CURLOPT_SSL_CTX_DATA(3) option.
This function will get called on all new connections made to a server, during
the SSL negotiation. The SSL_CTX pointer will be a new one every time.
To use this properly, a non-trivial amount of knowledge of the openssl libraries
is necessary. For example, using this function allows you to use openssl
callbacks to add additional validation code for certificates, and even to
change the actual URI of a HTTPS request (example used in the lib509 test
case). See also the example section for a replacement of the key, certificate
and trust file settings.
DEFAULT¶
NULL
PROTOCOLS¶
All TLS based protocols: HTTPS, FTPS, IMAPS, POP3, SMTPS etc.
EXAMPLE¶
TODO
AVAILABILITY¶
Added in 7.11.0. Only supported when built with OpenSSL.
RETURN VALUE¶
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
SEE ALSO¶
CURLOPT_SSL_CTX_DATA(3),
CURLOPT_SSL_VERIFYPEER(3),