Ubuntu Manpage: CURLOPT_SSL_OPTIONS

Provided by: libcurl4-doc_8.9.1-2ubuntu2.1_all

NAME

       CURLOPT_SSL_OPTIONS - 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. 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 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 fails 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. 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.

Works with wolfSSL on Windows, Linux (Debian, Ubuntu, Gentoo, Fedora, RHEL), macOS,
Android and iOS (added in 8.3.0), with GnuTLS (added in 8.5.0) or on Windows when
built to use OpenSSL (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)

DEFAULT

PROTOCOLS

       This functionality affects all TLS based protocols: HTTPS, FTPS, IMAPS, POP3S, SMTPS etc.

       All TLS backends support this option.

EXAMPLE

       int main(void)
       {
         CURL *curl = curl_easy_init();
         if(curl) {
           CURLcode res;
           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);
           res = curl_easy_perform(curl);
           curl_easy_cleanup(curl);
         }
       }

AVAILABILITY

       Added in curl 7.25.0

RETURN VALUE

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