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Updated: Thursday, June 13, 2019
 
 

CURLOPT_SSL_CTX_FUNCTION (3)

Name

CURLOPT_SSL_CTX_FUNCTION - SSL/CyaSSL or mbedTLS

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

curl_easy_setopt options                           CURLOPT_SSL_CTX_FUNCTION(3)



NAME
       CURLOPT_SSL_CTX_FUNCTION  -  SSL  context  callback  for OpenSSL, wolf-
       SSL/CyaSSL or mbedTLS

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,  wolfSSL/CyaSSL
       or mbedTLS. 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
       behavior of the SSL initialization. The ssl_ctx parameter is actually a
       pointer to the SSL library's SSL_CTX for OpenSSL or wolfSSL/CyaSSL, and
       a pointer to mbedtls_ssl_config 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) option.

       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  initial-
       ized  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  cer-
       tificates, and even to change the actual URI of an HTTPS request.

       WARNING:  The  CURLOPT_SSL_CTX_FUNCTION(3) callback allows the applica-
       tion to reach in and modify  SSL  details  in  the  connection  without
       libcurl  itself  knowing anything about it, which then subsequently can
       lead to libcurl unknowingly  reusing  SSL  connections  with  different
       properties. To remedy this you may set CURLOPT_FORBID_REUSE(3) from the
       callback function.

DEFAULT
       NULL

PROTOCOLS
       All TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

EXAMPLE
       See cacertinmem.c in docs/examples directory for usage example.

       https://curl.haxx.se/libcurl/c/cacertinmem.html

AVAILABILITY
       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.

RETURN VALUE
       CURLE_OK if supported; or an error such as:

       CURLE_NOT_BUILT_IN - Not supported by the SSL backend

       CURLE_UNKNOWN_OPTION


ATTRIBUTES
       See attributes(7) for descriptions of the following attributes:


       +---------------+------------------+
       |ATTRIBUTE TYPE | ATTRIBUTE VALUE  |
       +---------------+------------------+
       |Availability   | web/curl         |
       +---------------+------------------+
       |Stability      | Uncommitted      |
       +---------------+------------------+
SEE ALSO
       CURLOPT_SSL_CTX_DATA(3), CURLOPT_SSL_VERIFYPEER(3),



NOTES
       This     software     was    built    from    source    available    at
       https://github.com/oracle/solaris-userland.   The  original   community
       source    was    downloaded    from    https://github.com/curl/curl/ar-
       chive/curl-7_64_0.zip

       Further information about this software can be found on the open source
       community website at http://curl.haxx.se/.



libcurl 7.37.0                    19 Jun 2014
                                                   CURLOPT_SSL_CTX_FUNCTION(3)