Tribblix: manual page: CURLOPT_PROXY_SSL

CURLOPT_PROXY_SSL_OPTIONS(3) Introduction to Library Functions

NAME

CURLOPT_PROXY_SSL_OPTIONS - HTTPS proxy SSL behavior options

SYNOPSIS

#include <curl/curl.h>

CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_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/");
curl_easy_setopt(curl, CURLOPT_PROXY, "https://proxy");
/* weaken TLS only for use with silly proxies */
curl_easy_setopt(curl, CURLOPT_PROXY_SSL_OPTIONS, CURLSSLOPT_ALLOW_BEAST |
CURLSSLOPT_NO_REVOKE);
res = curl_easy_perform(curl);
curl_easy_cleanup(curl);
}
}

AVAILABILITY

Added in curl 7.52.0

RETURN VALUE

curl_easy_setopt(3) returns a CURLcode indicating success or error.

CURLE_OK (0) means everything was OK, non-zero means an error
occurred, see libcurl-errors(3).