CURLOPT_SSL_OPTIONS - SSL behavior options
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_SSL_OPTIONS, long bitmask);
Pass a long with a bitmask to tell libcurl about specific SSL
behaviors. Available bits:
- 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 is not 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 Secure Transport, NSS and OpenSSL.
- CURLSSLOPT_NO_REVOKE
- Tells libcurl to disable certificate revocation checks for those SSL
backends where such behavior is present. This option is only supported for
Schannel (the native Windows SSL library), with an exception in the case
of Windows' Untrusted Publishers block list which it seems cannot be
bypassed. (Added in 7.44.0)
- CURLSSLOPT_NO_PARTIALCHAIN
- Tells libcurl to not accept "partial" certificate chains, which
it otherwise does by default. This option is only supported for OpenSSL
and will fail the certificate verification if the chain ends with an
intermediate certificate and not with a root cert. (Added in 7.68.0)
- CURLSSLOPT_REVOKE_BEST_EFFORT
- Tells libcurl to ignore certificate revocation checks in case of missing
or offline distribution points for those SSL backends where such behavior
is present. This option is only supported for Schannel (the native Windows
SSL library). If combined with CURLSSLOPT_NO_REVOKE, the latter
takes precedence. (Added in 7.70.0)
- CURLSSLOPT_NATIVE_CA
- Tell libcurl to use the operating system's native CA store for certificate
verification. Works only on Windows when built to use OpenSSL. If you set
this option and also set a CA certificate file or directory then during
verification those certificates are searched in addition to the native CA
store. (Added in 7.71.0)
- CURLSSLOPT_AUTO_CLIENT_CERT
- Tell libcurl to automatically locate and use a client certificate for
authentication, when requested by the server. This option is only
supported for Schannel (the native Windows SSL library). Prior to 7.77.0
this was the default behavior in libcurl with Schannel. Since the server
can request any certificate that supports client authentication in the OS
certificate store it could be a privacy violation and unexpected. (Added
in 7.77.0)
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, (long)CURLSSLOPT_ALLOW_BEAST |
CURLSSLOPT_NO_REVOKE);
ret = curl_easy_perform(curl);
curl_easy_cleanup(curl);
}
Returns CURLE_OK if the option is supported, and
CURLE_UNKNOWN_OPTION if not.