draconisplusplus/subprojects/curl-8.10.1/docs/libcurl/opts/CURLOPT_USE_SSL.md

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---
c: Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
SPDX-License-Identifier: curl
Title: CURLOPT_USE_SSL
Section: 3
Source: libcurl
See-also:
- CURLOPT_PROXY_SSLVERSION (3)
- CURLOPT_SSLVERSION (3)
- CURLOPT_SSL_OPTIONS (3)
Protocol:
- FTP
- SMTP
- POP3
- IMAP
Added-in: 7.17.0
---
# NAME
CURLOPT_USE_SSL - request using SSL / TLS for the transfer
# SYNOPSIS
~~~c
#include <curl/curl.h>
CURLcode curl_easy_setopt(CURL *handle, CURLOPT_USE_SSL, long level);
~~~
# DESCRIPTION
Pass a long using one of the values from below, to make libcurl use your
desired *level* of SSL for the transfer.
These are all protocols that start out plain text and get "upgraded" to SSL
using the STARTTLS command.
This is for enabling SSL/TLS when you use FTP, SMTP, POP3, IMAP etc.
## CURLUSESSL_NONE
do not attempt to use SSL.
## CURLUSESSL_TRY
Try using SSL, proceed as normal otherwise. Note that server may close the
connection if the negotiation does not succeed.
## CURLUSESSL_CONTROL
Require SSL for the control connection or fail with *CURLE_USE_SSL_FAILED*.
## CURLUSESSL_ALL
Require SSL for all communication or fail with *CURLE_USE_SSL_FAILED*.
# DEFAULT
CURLUSESSL_NONE
# %PROTOCOLS%
# EXAMPLE
~~~c
int main(void)
{
CURL *curl = curl_easy_init();
if(curl) {
curl_easy_setopt(curl, CURLOPT_URL, "ftp://example.com/dir/file.ext");
/* require use of SSL for this, or fail */
curl_easy_setopt(curl, CURLOPT_USE_SSL, (long)CURLUSESSL_ALL);
/* Perform the request */
curl_easy_perform(curl);
}
}
~~~
# HISTORY
This option was known as CURLOPT_FTP_SSL up to 7.16.4, and the constants were
known as CURLFTPSSL_* Handled by LDAP since 7.81.0. Fully supported by the
OpenLDAP backend only.
# %AVAILABILITY%
# RETURN VALUE
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.