CURLOPT_SSL_CTX_FUNCTION(3)curl_easy_setopt optionsCURLOPT_SSL_CTX_FUNCTION(3)NAMECURLOPT_SSL_CTX_FUNCTION - SSL context callback for OpenSSL or wolf‐
SSL/CyaSSL
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 or wolf‐
SSL/CyaSSL. If libcurl was built against another SSL library this func‐
tionality is absent.
Pass a pointer to your callback function, which should match the proto‐
type shown above.
This callback function gets called by libcurl just before the initial‐
ization 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 library's SSL_CTX. If an error is returned from
the callback no attempt to establish a connection is made and the per‐
form operation will return the callback's 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 your SSL
library is necessary. For example, you can use this function to call
library-specific callbacks to add additional validation code for cer‐
tificates, and even to change the actual URI of a HTTPS request (exam‐
ple 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, POP3S, SMTPS etc.
EXAMPLE
TODO
AVAILABILITY
Added in 7.11.0 for OpenSSL. Added in 7.42.0 for wolfSSL/CyaSSL. Other
SSL backends not supported.
RETURN VALUE
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION
if not.
SEE ALSOCURLOPT_SSL_CTX_DATA(3), CURLOPT_SSL_VERIFYPEER(3),
libcurl 7.37.0 19 Jun 2014 CURLOPT_SSL_CTX_FUNCTION(3)
