The callback should return a password string. See <span class="sectref"><a href="#section4">Callback Options</a></span>
for more info.</p></dd>
<dt><b class="option">-post_handshake</b> <i class="arg">bool</i></dt>
<dd><p>Allow post-handshake session ticket updates.</p></dd>
<dt><b class="option">-request</b> <i class="arg">bool</i></dt>
<dd><p>Request a certificate from the peer during the SSL handshake. This is needed
to do Certificate Validation. Starting in TclTLS 1.8, the default is
<b class="const">true</b>.
<b class="const">true</b>. Starting in TclTLS 2.0, If set to <b class="const">false</b> and
<b class="option">-require</b> is <b class="const">true</b>, then this will be overridden to <b class="const">true</b>.
See <span class="sectref"><a href="#section3">Certificate Validation</a></span> for more details.</p></dd>
<dt><b class="option">-require</b> <i class="arg">bool</i></dt>
<dd><p>Require a valid certificate from the peer during the SSL handshake. If this is
set to true, then <b class="option">-request</b> must also be set to true and a either
<b class="option">-cadir</b>, <b class="option">-cafile</b>, <b class="option">-castore</b>, or a platform default
must be provided in order to validate against. The default in TclTLS 1.8 and
earlier versions is <b class="const">false</b> since not all platforms have certificates to
validate against in a form compatible with OpenSSL.
validate against in a form compatible with OpenSSL. Starting in TclTLS 2.0,
the default is <b class="const">true</b>.
See <span class="sectref"><a href="#section3">Certificate Validation</a></span> for more details.</p></dd>
<dt><b class="option">-security_level</b> <i class="arg">integer</i></dt>
<dd><p>Specifies the security level (value from 0 to 5). The security level affects
the allowed cipher suite encryption algorithms, supported ECC curves,
supported signature algorithms, DH parameter sizes, certificate key sizes
and signature algorithms. The default is 1 prior to OpenSSL 3.2 and 2
thereafter. Level 3 and higher disable support for session tickets and

Starting with OpenSSL 3.2 on MS Windows, set to &quot;<b class="const">org.openssl.winstore://</b>&quot;
to use the built-in MS Windows Certificate Store.
This store only supports root certificate stores. See
<span class="sectref"><a href="#section3">Certificate Validation</a></span> for more details.</p></dd>
<dt><b class="option">-request</b> <i class="arg">bool</i></dt>
<dd><p>Request a certificate from the peer during the SSL handshake. This is needed
to do Certificate Validation. Starting in TclTLS 1.8, the default is
<b class="const">true</b>. Starting in TclTLS 2.0, If set to <b class="const">false</b> and
<b class="option">-require</b> is <b class="const">true</b>, then this will be overridden to <b class="const">true</b>.
<b class="const">true</b>. In addition, the client can manually inspect and accept or reject
In addition, the client can manually inspect and accept or reject
each certificate using the <i class="arg">-validatecommand</i> option.</p></dd>
<dt><b class="option">-require</b> <i class="arg">bool</i></dt>
<dd><p>Require a valid certificate from the peer during the SSL handshake. If this is
set to true, then <b class="option">-request</b> must also be set to true and a either
<b class="option">-cadir</b>, <b class="option">-cafile</b>, <b class="option">-castore</b>, or a platform default
must be provided in order to validate against. The default in TclTLS 1.8 and
earlier versions is <b class="const">false</b> since not all platforms have certificates to
validate against in a form compatible with OpenSSL.</p></dd>
validate against in a form compatible with OpenSSL. Starting in TclTLS 2.0,
the default is <b class="const">true</b>.</p></dd>
</dl>
</div>
<div id="subsection3" class="doctools_subsection"><h3><a name="subsection3">When are command line options needed?</a></h3>
<p>In TclTLS 1.8 and earlier versions, certificate validation is
<em>NOT</em> enabled by default. This limitation is due to the lack of a common
cross platform database of Certificate Authority (CA) provided certificates to
validate against. Many Linux systems natively support OpenSSL and thus have
these certificates installed as part of the OS, but MacOS and MS Windows do not.
Staring in TclTLS 2.0, this has been changed to require certificate validation
In order to use the <b class="option">-require</b> option, one of the following
by default. In order to use the <b class="option">-require</b> option, one of the following
must be true:</p>
<ul class="doctools_itemized">
<li><p>On Linux and Unix systems with OpenSSL already installed or if the CA
certificates are available in PEM format, and if they are stored in the
standard locations, or if the <b class="variable">SSL_CERT_DIR</b> or <b class="variable">SSL_CERT_FILE</b>
environment variables are set, then <b class="option">-cadir</b>, <b class="option">-cadir</b>,
and <b class="option">-castore</b> aren't needed.</p></li>

[opt_def -post_handshake [arg bool]]
Allow post-handshake session ticket updates.

[opt_def -request [arg bool]]
Request a certificate from the peer during the SSL handshake. This is needed
to do Certificate Validation. Starting in TclTLS 1.8, the default is
[const true].
[const true]. Starting in TclTLS 2.0, If set to [const false] and
[option -require] is [const true], then this will be overridden to [const true].
See [sectref "Certificate Validation"] for more details.

[opt_def -require [arg bool]]
Require a valid certificate from the peer during the SSL handshake. If this is
set to true, then [option -request] must also be set to true and a either
[option -cadir], [option -cafile], [option -castore], or a platform default
must be provided in order to validate against. The default in TclTLS 1.8 and
earlier versions is [const false] since not all platforms have certificates to
validate against in a form compatible with OpenSSL.
validate against in a form compatible with OpenSSL. Starting in TclTLS 2.0,
the default is [const true].
See [sectref "Certificate Validation"] for more details.

[opt_def -security_level [arg integer]]
Specifies the security level (value from 0 to 5). The security level affects
the allowed cipher suite encryption algorithms, supported ECC curves,
supported signature algorithms, DH parameter sizes, certificate key sizes
and signature algorithms. The default is 1 prior to OpenSSL 3.2 and 2

to use the built-in MS Windows Certificate Store.
This store only supports root certificate stores. See
[sectref "Certificate Validation"] for more details.

[opt_def -request [arg bool]]
Request a certificate from the peer during the SSL handshake. This is needed
to do Certificate Validation. Starting in TclTLS 1.8, the default is
[const true]. Starting in TclTLS 2.0, If set to [const false] and
[option -require] is [const true], then this will be overridden to [const true].
[const true]. In addition, the client can manually inspect and accept or reject
In addition, the client can manually inspect and accept or reject
each certificate using the [arg -validatecommand] option.

[opt_def -require [arg bool]]
Require a valid certificate from the peer during the SSL handshake. If this is
set to true, then [option -request] must also be set to true and a either
[option -cadir], [option -cafile], [option -castore], or a platform default
must be provided in order to validate against. The default in TclTLS 1.8 and
earlier versions is [const false] since not all platforms have certificates to
validate against in a form compatible with OpenSSL.
validate against in a form compatible with OpenSSL. Starting in TclTLS 2.0,
the default is [const true].

[list_end]

[subsection "When are command line options needed?"]

In TclTLS 1.8 and earlier versions, certificate validation is
[emph NOT] enabled by default. This limitation is due to the lack of a common
cross platform database of Certificate Authority (CA) provided certificates to
validate against. Many Linux systems natively support OpenSSL and thus have
these certificates installed as part of the OS, but MacOS and MS Windows do not.
Staring in TclTLS 2.0, this has been changed to require certificate validation
In order to use the [option -require] option, one of the following
by default. In order to use the [option -require] option, one of the following
must be true:

[list_begin itemized]

[item]
On Linux and Unix systems with OpenSSL already installed or if the CA
certificates are available in PEM format, and if they are stored in the

.TP
\fB-post_handshake\fR \fIbool\fR
Allow post-handshake session ticket updates\&.
.TP
\fB-request\fR \fIbool\fR
Request a certificate from the peer during the SSL handshake\&. This is needed
to do Certificate Validation\&. Starting in TclTLS 1\&.8, the default is
\fBtrue\fR\&.
\fBtrue\fR\&. Starting in TclTLS 2\&.0, If set to \fBfalse\fR and
\fB-require\fR is \fBtrue\fR, then this will be overridden to \fBtrue\fR\&.
See \fBCertificate Validation\fR for more details\&.
.TP
\fB-require\fR \fIbool\fR
Require a valid certificate from the peer during the SSL handshake\&. If this is
set to true, then \fB-request\fR must also be set to true and a either
\fB-cadir\fR, \fB-cafile\fR, \fB-castore\fR, or a platform default
must be provided in order to validate against\&. The default in TclTLS 1\&.8 and
earlier versions is \fBfalse\fR since not all platforms have certificates to
validate against in a form compatible with OpenSSL\&.
validate against in a form compatible with OpenSSL\&. Starting in TclTLS 2\&.0,
the default is \fBtrue\fR\&.
See \fBCertificate Validation\fR for more details\&.
.TP
\fB-security_level\fR \fIinteger\fR
Specifies the security level (value from 0 to 5)\&. The security level affects
the allowed cipher suite encryption algorithms, supported ECC curves,
supported signature algorithms, DH parameter sizes, certificate key sizes
and signature algorithms\&. The default is 1 prior to OpenSSL 3\&.2 and 2

to use the built-in MS Windows Certificate Store\&.
This store only supports root certificate stores\&. See
\fBCertificate Validation\fR for more details\&.
.TP
\fB-request\fR \fIbool\fR
Request a certificate from the peer during the SSL handshake\&. This is needed
to do Certificate Validation\&. Starting in TclTLS 1\&.8, the default is
\fBtrue\fR\&. Starting in TclTLS 2\&.0, If set to \fBfalse\fR and
\fB-require\fR is \fBtrue\fR, then this will be overridden to \fBtrue\fR\&.
\fBtrue\fR\&. In addition, the client can manually inspect and accept or reject
In addition, the client can manually inspect and accept or reject
each certificate using the \fI-validatecommand\fR option\&.
.TP
\fB-require\fR \fIbool\fR
Require a valid certificate from the peer during the SSL handshake\&. If this is
set to true, then \fB-request\fR must also be set to true and a either
\fB-cadir\fR, \fB-cafile\fR, \fB-castore\fR, or a platform default
must be provided in order to validate against\&. The default in TclTLS 1\&.8 and
earlier versions is \fBfalse\fR since not all platforms have certificates to
validate against in a form compatible with OpenSSL\&.
validate against in a form compatible with OpenSSL\&. Starting in TclTLS 2\&.0,
the default is \fBtrue\fR\&.
.PP
.SS "WHEN ARE COMMAND LINE OPTIONS NEEDED?"
In TclTLS 1\&.8 and earlier versions, certificate validation is
\fINOT\fR enabled by default\&. This limitation is due to the lack of a common
cross platform database of Certificate Authority (CA) provided certificates to
validate against\&. Many Linux systems natively support OpenSSL and thus have
these certificates installed as part of the OS, but MacOS and MS Windows do not\&.
Staring in TclTLS 2\&.0, this has been changed to require certificate validation
In order to use the \fB-require\fR option, one of the following
by default\&. In order to use the \fB-require\fR option, one of the following
must be true:
.IP \(bu
On Linux and Unix systems with OpenSSL already installed or if the CA
certificates are available in PEM format, and if they are stored in the
standard locations, or if the \fBSSL_CERT_DIR\fR or \fBSSL_CERT_FILE\fR
environment variables are set, then \fB-cadir\fR, \fB-cadir\fR,
and \fB-castore\fR aren't needed\&.

    char *model			= NULL;
    char *servername		= NULL;	/* hostname for Server Name Indication */
    char *session_id		= NULL;
    Tcl_Obj *alpn		= NULL;
    int ssl2 = 0, ssl3 = 0;
    int tls1 = 1, tls1_1 = 1, tls1_2 = 1, tls1_3 = 1;
    int proto = 0, level = -1;
    int verify = 0, require = 0, request = 1, post_handshake = 0;
    int verify = 0, require = 1, request = 1, post_handshake = 0;

    dprintf("Called");

#if defined(NO_TLS1) || defined(OPENSSL_NO_TLS1)
    tls1 = 0;
#endif
#if defined(NO_TLS1_1) || defined(OPENSSL_NO_TLS1_1)

	OPTOBJ("-validatecommand", vcmd);
	OPTOBJ("-vcmd", vcmd);

	OPTBAD("option", "-alpn, -cadir, -cafile, -castore, -cert, -certfile, -cipher, -ciphersuites, -command, -dhparams, -key, -keyfile, -model, -password, -post_handshake, -request, -require, -security_level, -server, -servername, -session_id, -ssl2, -ssl3, -tls1, -tls1.1, -tls1.2, -tls1.3, or -validatecommand");

	return TCL_ERROR;
    }
    if (require)		request = 1;
    if (request)		verify |= SSL_VERIFY_CLIENT_ONCE | SSL_VERIFY_PEER;
    if (request && require)	verify |= SSL_VERIFY_FAIL_IF_NO_PEER_CERT;
    if (request && post_handshake)	verify |= SSL_VERIFY_POST_HANDSHAKE;
    if (request && post_handshake) verify |= SSL_VERIFY_POST_HANDSHAKE;
    if (verify == 0)		verify = SSL_VERIFY_NONE;

    proto |= (ssl2 ? TLS_PROTO_SSL2 : 0);
    proto |= (ssl3 ? TLS_PROTO_SSL3 : 0);
    proto |= (tls1 ? TLS_PROTO_TLS1 : 0);
    proto |= (tls1_1 ? TLS_PROTO_TLS1_1 : 0);
    proto |= (tls1_2 ? TLS_PROTO_TLS1_2 : 0);

#include <openssl/rand.h>
#include <openssl/opensslv.h>

/* Windows needs to know which symbols to export. */
#ifdef BUILD_tls
#undef TCL_STORAGE_CLASS
#define TCL_STORAGE_CLASS DLLEXPORT
#endif /* BUILD_udp */
#endif /* BUILD_tls */

/* Handle TCL 8.6 CONST changes */
#ifndef CONST86
#   if TCL_MAJOR_VERSION > 8
#	define CONST86 const
#   else
#	define CONST86