166 lines
6.1 KiB
Groff
166 lines
6.1 KiB
Groff
.\" **************************************************************************
|
|
.\" * _ _ ____ _
|
|
.\" * Project ___| | | | _ \| |
|
|
.\" * / __| | | | |_) | |
|
|
.\" * | (__| |_| | _ <| |___
|
|
.\" * \___|\___/|_| \_\_____|
|
|
.\" *
|
|
.\" * Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
|
|
.\" *
|
|
.\" * This software is licensed as described in the file COPYING, which
|
|
.\" * you should have received as part of this distribution. The terms
|
|
.\" * are also available at https://curl.se/docs/copyright.html.
|
|
.\" *
|
|
.\" * You may opt to use, copy, modify, merge, publish, distribute and/or sell
|
|
.\" * copies of the Software, and permit persons to whom the Software is
|
|
.\" * furnished to do so, under the terms of the COPYING file.
|
|
.\" *
|
|
.\" * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
|
|
.\" * KIND, either express or implied.
|
|
.\" *
|
|
.\" * SPDX-License-Identifier: curl
|
|
.\" *
|
|
.\" **************************************************************************
|
|
.\"
|
|
.TH CURLINFO_TLS_SSL_PTR 3 "23 Feb 2016" libcurl libcurl
|
|
.SH NAME
|
|
CURLINFO_TLS_SESSION, CURLINFO_TLS_SSL_PTR \- get TLS session info
|
|
.SH SYNOPSIS
|
|
.nf
|
|
#include <curl/curl.h>
|
|
|
|
CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_TLS_SSL_PTR,
|
|
struct curl_tlssessioninfo **session);
|
|
|
|
/* if you need compatibility with libcurl < 7.48.0 use
|
|
CURLINFO_TLS_SESSION instead: */
|
|
|
|
CURLcode curl_easy_getinfo(CURL *handle, CURLINFO_TLS_SESSION,
|
|
struct curl_tlssessioninfo **session);
|
|
.SH DESCRIPTION
|
|
Pass a pointer to a \fIstruct curl_tlssessioninfo *\fP. The pointer is
|
|
initialized to refer to a \fIstruct curl_tlssessioninfo *\fP that contains an
|
|
enum indicating the SSL library used for the handshake and a pointer to the
|
|
respective internal TLS session structure of this underlying SSL library.
|
|
|
|
This option may be useful for example to extract certificate information in a
|
|
format convenient for further processing, such as manual validation. Refer to
|
|
the \fBLIMITATIONS\fP section.
|
|
|
|
.nf
|
|
struct curl_tlssessioninfo {
|
|
curl_sslbackend backend;
|
|
void *internals;
|
|
};
|
|
.fi
|
|
|
|
The \fIbackend\fP struct member is one of the defines in the CURLSSLBACKEND_*
|
|
series: CURLSSLBACKEND_NONE (when built without TLS support),
|
|
CURLSSLBACKEND_WOLFSSL, CURLSSLBACKEND_SECURETRANSPORT, CURLSSLBACKEND_GNUTLS,
|
|
CURLSSLBACKEND_MBEDTLS, CURLSSLBACKEND_NSS, CURLSSLBACKEND_OPENSSL,
|
|
CURLSSLBACKEND_SCHANNEL or CURLSSLBACKEND_MESALINK. (Note that the OpenSSL
|
|
forks are all reported as just OpenSSL here.)
|
|
|
|
The \fIinternals\fP struct member points to a TLS library specific pointer for
|
|
the active ("in use") SSL connection, with the following underlying types:
|
|
.RS
|
|
.IP GnuTLS
|
|
\fBgnutls_session_t\fP
|
|
.IP NSS
|
|
\fBPRFileDesc *\fP
|
|
.IP OpenSSL
|
|
\fICURLINFO_TLS_SESSION(3)\fP: \fBSSL_CTX *\fP
|
|
|
|
\fICURLINFO_TLS_SSL_PTR(3)\fP: \fBSSL *\fP
|
|
.RE
|
|
Since 7.48.0 the \fIinternals\fP member can point to these other SSL backends
|
|
as well:
|
|
.RS
|
|
.IP mbedTLS
|
|
\fBmbedTLS_ssl_context *\fP
|
|
.IP "Secure Channel"
|
|
\fBCtxtHandle *\fP
|
|
.IP "Secure Transport"
|
|
\fBSSLContext *\fP
|
|
.IP "wolfSSL"
|
|
\fBSSL *\fP
|
|
.RE
|
|
|
|
If the \fIinternals\fP pointer is NULL then either the SSL backend is not
|
|
supported, an SSL session has not yet been established or the connection is no
|
|
longer associated with the easy handle (e.g. \fIcurl_easy_perform(3)\fP has
|
|
returned).
|
|
.SH LIMITATIONS
|
|
This option has some limitations that could make it unsafe when it comes to
|
|
the manual verification of certificates.
|
|
|
|
This option only retrieves the first in-use SSL session pointer for your easy
|
|
handle, however your easy handle may have more than one in-use SSL session if
|
|
using FTP over SSL. That is because the FTP protocol has a control channel and
|
|
a data channel and one or both may be over SSL. Currently there is no way to
|
|
retrieve a second in-use SSL session associated with an easy handle.
|
|
|
|
This option has not been thoroughly tested with clear text protocols that can
|
|
be upgraded/downgraded to/from SSL: FTP, SMTP, POP3, IMAP when used with
|
|
\fICURLOPT_USE_SSL(3)\fP. Though you can to retrieve the SSL pointer, it's
|
|
possible that before you can do that, data (including auth) may have already
|
|
been sent over a connection after it was upgraded.
|
|
|
|
Renegotiation. If unsafe renegotiation or renegotiation in a way that the
|
|
certificate is allowed to change is allowed by your SSL library this may occur
|
|
and the certificate may change, and data may continue to be sent or received
|
|
after renegotiation but before you are able to get the (possibly) changed SSL
|
|
pointer, with the (possibly) changed certificate information.
|
|
|
|
Instead of using this option to poll for certificate changes use
|
|
\fICURLOPT_SSL_CTX_FUNCTION(3)\fP to set a verification callback, if supported.
|
|
That is safer and does not suffer from any of the problems above.
|
|
|
|
How are you using this option? Are you affected by any of these limitations?
|
|
Please let us know by making a comment at
|
|
https://github.com/curl/curl/issues/685
|
|
.SH PROTOCOLS
|
|
All TLS-based
|
|
.SH EXAMPLE
|
|
.nf
|
|
#include <curl/curl.h>
|
|
#include <openssl/ssl.h>
|
|
|
|
CURL *curl;
|
|
static size_t wf(void *ptr, size_t size, size_t nmemb, void *stream)
|
|
{
|
|
const struct curl_tlssessioninfo *info = NULL;
|
|
CURLcode res = curl_easy_getinfo(curl, CURLINFO_TLS_SSL_PTR, &info);
|
|
if(info && !res) {
|
|
if(CURLSSLBACKEND_OPENSSL == info->backend) {
|
|
printf("OpenSSL ver. %s\\n", SSL_get_version((SSL*)info->internals));
|
|
}
|
|
}
|
|
return size * nmemb;
|
|
}
|
|
|
|
int main(int argc, char** argv)
|
|
{
|
|
CURLcode res;
|
|
curl = curl_easy_init();
|
|
if(curl) {
|
|
curl_easy_setopt(curl, CURLOPT_URL, "https://example.com");
|
|
curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, wf);
|
|
res = curl_easy_perform(curl);
|
|
curl_easy_cleanup(curl);
|
|
}
|
|
return res;
|
|
}
|
|
.fi
|
|
.SH AVAILABILITY
|
|
Added in 7.48.0.
|
|
|
|
This option supersedes \fICURLINFO_TLS_SESSION(3)\fP which was added in 7.34.0.
|
|
This option is exactly the same as that option except in the case of OpenSSL.
|
|
.SH RETURN VALUE
|
|
Returns CURLE_OK if the option is supported, and CURLE_UNKNOWN_OPTION if not.
|
|
.SH "SEE ALSO"
|
|
.BR curl_easy_getinfo (3),
|
|
.BR curl_easy_setopt (3),
|
|
.BR CURLINFO_TLS_SESSION (3)
|