CURLOPT_SSL_CTX_FUNCTION - SSL context callback for OpenSSL, wolfSSL/CyaSSL or
CURLcode ssl_ctx_callback(CURL *curl, void *ssl_ctx, void *userptr);
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_CTX_FUNCTION,
This option only works for libcurl powered by OpenSSL, wolfSSL/CyaSSL or
mbedTLS. If libcurl was built against another SSL library this functionality
Pass a pointer to your callback function, which should match the prototype shown
This callback function gets called by libcurl just before the initialization of
an SSL connection after having processed all other SSL related options to give
a last chance to an application to modify the behaviour of the SSL
initialization. The ssl_ctx
parameter is actually a pointer to the SSL
for OpenSSL or wolfSSL/CyaSSL, and a pointer to
for mbedTLS. If an error is returned from the
callback no attempt to establish a connection is made and the perform
operation will return the callback's error code. Set the userptr
argument with the CURLOPT_SSL_CTX_DATA(3)
This function will get called on all new connections made to a server, during
the SSL negotiation. The ssl_ctx
will point to a newly initialized
object each time, but note the pointer may be the same as from a prior call.
To use this properly, a non-trivial amount of knowledge of your SSL library is
necessary. For example, you can use this function to call library-specific
callbacks to add additional validation code for certificates, and even to
change the actual URI of an HTTPS request.
All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.
See cacertinmem.c in docs/examples directory for usage example.
Added in 7.11.0 for OpenSSL. Added in 7.42.0 for wolfSSL/CyaSSL. Added in 7.54.0
for mbedTLS. Other SSL backends not supported.
CURLE_OK if supported; or an error such as:
CURLE_NOT_BUILT_IN - Not supported by the SSL backend