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1---
2c: Copyright (C) Daniel Stenberg, <daniel.se>, et al.
3SPDX-License-Identifier: curl
4Title: CURLOPT_PROXY_SSL_OPTIONS
5Section: 3
6Source: libcurl
7See-also:
8  - CURLOPT_PROXY_SSLVERSION (3)
9  - CURLOPT_PROXY_SSL_CIPHER_LIST (3)
10  - CURLOPT_SSLVERSION (3)
11  - CURLOPT_SSL_CIPHER_LIST (3)
12---
13
14# NAME
15
16CURLOPT_PROXY_SSL_OPTIONS - HTTPS proxy SSL behavior options
17
18# SYNOPSIS
19
20~~~c
21#include <curl/curl.h>
22
23CURLcode curl_easy_setopt(CURL *handle, CURLOPT_PROXY_SSL_OPTIONS,
24                          long bitmask);
25~~~
26
27# DESCRIPTION
28
29Pass a long with a bitmask to tell libcurl about specific SSL
30behaviors. Available bits:
31
32## CURLSSLOPT_ALLOW_BEAST
33
34Tells libcurl to not attempt to use any workarounds for a security flaw in the
35SSL3 and TLS1.0 protocols. If this option is not used or this bit is set to 0,
36the SSL layer libcurl uses may use a work-around for this flaw although it
37might cause interoperability problems with some (older) SSL implementations.
38WARNING: avoiding this work-around lessens the security, and by setting this
39option to 1 you ask for exactly that. This option is only supported for Secure
40Transport and OpenSSL.
41
42## CURLSSLOPT_NO_REVOKE
43
44Tells libcurl to disable certificate revocation checks for those SSL backends
45where such behavior is present. This option is only supported for Schannel
46(the native Windows SSL library), with an exception in the case of Windows'
47Untrusted Publishers block list which it seems cannot be bypassed. (Added in
487.44.0)
49
50## CURLSSLOPT_NO_PARTIALCHAIN
51
52Tells libcurl to not accept "partial" certificate chains, which it otherwise
53does by default. This option is only supported for OpenSSL and fails the
54certificate verification if the chain ends with an intermediate certificate
55and not with a root cert. (Added in 7.68.0)
56
57## CURLSSLOPT_REVOKE_BEST_EFFORT
58
59Tells libcurl to ignore certificate revocation checks in case of missing or
60offline distribution points for those SSL backends where such behavior is
61present. This option is only supported for Schannel (the native Windows SSL
62library). If combined with *CURLSSLOPT_NO_REVOKE*, the latter takes
63precedence. (Added in 7.70.0)
64
65## CURLSSLOPT_NATIVE_CA
66
67Tell libcurl to use the operating system's native CA store for certificate
68verification. If you set this option and also set a CA certificate file or
69directory then during verification those certificates are searched in addition
70to the native CA store.
71
72Works with wolfSSL on Windows, Linux (Debian, Ubuntu, Gentoo, Fedora, RHEL),
73macOS, Android and iOS (added in 8.3.0), with GnuTLS (added in 8.5.0) or on
74Windows when built to use OpenSSL (Added in 7.71.0).
75
76## CURLSSLOPT_AUTO_CLIENT_CERT
77
78Tell libcurl to automatically locate and use a client certificate for
79authentication, when requested by the server. This option is only supported
80for Schannel (the native Windows SSL library). Prior to 7.77.0 this was the
81default behavior in libcurl with Schannel. Since the server can request any
82certificate that supports client authentication in the OS certificate store it
83could be a privacy violation and unexpected.
84(Added in 7.77.0)
85
86# DEFAULT
87
880
89
90# PROTOCOLS
91
92All TLS-based protocols
93
94# EXAMPLE
95
96~~~c
97int main(void)
98{
99  CURL *curl = curl_easy_init();
100  if(curl) {
101    CURLcode res;
102    curl_easy_setopt(curl, CURLOPT_URL, "https://example.com/");
103    curl_easy_setopt(curl, CURLOPT_PROXY, "https://proxy");
104    /* weaken TLS only for use with silly proxies */
105    curl_easy_setopt(curl, CURLOPT_PROXY_SSL_OPTIONS, CURLSSLOPT_ALLOW_BEAST |
106                     CURLSSLOPT_NO_REVOKE);
107    res = curl_easy_perform(curl);
108    curl_easy_cleanup(curl);
109  }
110}
111~~~
112
113# AVAILABILITY
114
115Added in 7.52.0
116
117# RETURN VALUE
118
119Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
120