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CURLOPT_SSL_OPTIONS

Section: curl_easy_setopt options (3)
Updated: May 31, 2017
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NAME

CURLOPT_SSL_OPTIONS - set SSL behavior options

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_OPTIONS, long bitmask);

DESCRIPTION

Pass a long with a bitmask to tell libcurl about specific SSL behaviors.

CURLSSLOPT_ALLOW_BEAST tells libcurl to not attempt to use any workarounds for a security flaw in the SSL3 and TLS1.0 protocols. If this option isn't used or this bit is set to 0, the SSL layer libcurl uses may use a work-around for this flaw although it might cause interoperability problems with some (older) SSL implementations. WARNING: avoiding this work-around lessens the security, and by setting this option to 1 you ask for exactly that. This option is only supported for DarwinSSL, NSS and OpenSSL.

Added in 7.44.0:

CURLSSLOPT_NO_REVOKE tells libcurl to disable certificate revocation checks for those SSL backends where such behavior is present. Currently this option is only supported for WinSSL (the native Windows SSL library), with an exception in the case of Windows' Untrusted Publishers blacklist which it seems can't be bypassed. This option may have broader support to accommodate other SSL backends in the future. https://curl.haxx.se/docs/ssl-compared.html

DEFAULT

PROTOCOLS

All TLS-based protocols

EXAMPLE

CURL *curl = curl_easy_init();
if(curl) {
  curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
  /* weaken TLS only for use with silly servers */
  curl_easy_setopt(curl, CURLOPT_SSL_OPTIONS, CURLSSLOPT_ALLOW_BEAST |
                   CURLSSLOPT_NO_REVOKE);
  ret = curl_easy_perform(curl);
  curl_easy_cleanup(curl);
}

AVAILABILITY

Added in 7.25.0

RETURN VALUE

Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.