char *ciphers	        = NULL;
    char *CAfile	        = NULL;
    char *CAdir		        = NULL;
    char *DHparams	        = NULL;
    char *model		        = NULL;
#ifndef OPENSSL_NO_TLSEXT
    char *servername	        = NULL;	/* hostname for Server Name Indication */
    Tcl_Obj *alpn		= NULL;
#endif
    int ssl2 = 0, ssl3 = 0;
    int tls1 = 1, tls1_1 = 1, tls1_2 = 1, tls1_3 = 1;
    int proto = 0;
    int verify = 0, require = 0, request = 1;

    dprintf("Called");

	OPTSTR( "-model", model);
	OPTOBJ( "-password", password);
	OPTBOOL( "-require", require);
	OPTBOOL( "-request", request);
	OPTBOOL( "-server", server);
#ifndef OPENSSL_NO_TLSEXT
        OPTSTR( "-servername", servername);
	OPTOBJ( "-alpn", alpn);
#endif

	OPTBOOL( "-ssl2", ssl2);
	OPTBOOL( "-ssl3", ssl3);
	OPTBOOL( "-tls1", tls1);
	OPTBOOL( "-tls1.1", tls1_1);
	OPTBOOL( "-tls1.2", tls1_2);
	OPTBOOL( "-tls1.3", tls1_3);
  OPTBYTE("-cert", cert, cert_len);
  OPTBYTE("-key", key, key_len);

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

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

        if (!SSL_set_tlsext_host_name(statePtr->ssl, servername) && require) {
            Tcl_AppendResult(interp, "setting TLS host name extension failed",
                (char *) NULL);
            Tls_Free((char *) statePtr);
            return TCL_ERROR;
        }
    }
    if (alpn) {
	/* Convert a Tcl list into a protocol-list in wire-format */
	unsigned char *protos, *p;
	unsigned int protoslen = 0;
	int i, len, cnt;
	Tcl_Obj **list;
	if (Tcl_ListObjGetElements(interp, alpn, &cnt, &list) != TCL_OK) {
	    Tls_Free((char *) statePtr);
	    return TCL_ERROR;
	}
	/* Determine the memory required for the protocol-list */
	for (i = 0; i < cnt; i++) {
	    Tcl_GetStringFromObj(list[i], &len);
	    if (len > 255) {
		Tcl_AppendResult(interp, "alpn protocol name too long",
		  (char *) NULL);
		Tls_Free((char *) statePtr);
		return TCL_ERROR;
	    }
	    protoslen += 1 + len;
	}
	/* Build the complete protocol-list */
	protos = ckalloc(protoslen);
	/* protocol-lists consist of 8-bit length-prefixed, byte strings */
	for (i = 0, p = protos; i < cnt; i++) {
	    char *str = Tcl_GetStringFromObj(list[i], &len);
	    *p++ = len;
	    memcpy(p, str, len);
	    p += len;
	}
	/* Note: This functions reverses the return value convention */
	if (SSL_set_alpn_protos(statePtr->ssl, protos, protoslen)) {
	    Tcl_AppendResult(interp, "failed to set alpn protocols",
	      (char *) NULL);
	    Tls_Free((char *) statePtr);
	    ckfree(protos);
	    return TCL_ERROR;
	}
	/* SSL_set_alpn_protos makes a copy of the protocol-list */
	ckfree(protos);
    }
#endif

    /*
     * SSL Callbacks
     */

    SSL_set_app_data(statePtr->ssl, (VOID *)statePtr);	/* point back to us */

{
    State *statePtr;
    X509 *peer;
    Tcl_Obj *objPtr;
    Tcl_Channel chan;
    char *channelName, *ciphers;
    int mode;
#ifndef OPENSSL_NO_TLSEXT
    const unsigned char *proto;
    unsigned int len;
#endif

    dprintf("Called");

    switch (objc) {
	case 2:
	    channelName = Tcl_GetStringFromObj(objv[1], NULL);
	    break;

	case 3:
	    if (!strcmp (Tcl_GetString (objv[1]), "-local")) {
		channelName = Tcl_GetStringFromObj(objv[2], NULL);
		break;
	    }
	    /* else fall... */
	    __attribute__((fallthrough));
	default:
	    Tcl_WrongNumArgs(interp, 1, objv, "?-local? channel");
	    return TCL_ERROR;
    }

    chan = Tcl_GetChannel(interp, channelName, &mode);
    if (chan == (Tcl_Channel) NULL) {

    ciphers = (char*)SSL_get_cipher(statePtr->ssl);
    if (ciphers != NULL && strcmp(ciphers, "(NONE)")!=0) {
	Tcl_ListObjAppendElement(interp, objPtr,
		Tcl_NewStringObj("cipher", -1));
	Tcl_ListObjAppendElement(interp, objPtr,
		Tcl_NewStringObj(SSL_get_cipher(statePtr->ssl), -1));
    }

#ifndef OPENSSL_NO_TLSEXT
    /* Report the selected protocol as a result of the negotiation */
    SSL_get0_alpn_selected(statePtr->ssl, &proto, &len);
    Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("alpn", -1));
    Tcl_ListObjAppendElement(interp, objPtr,
      Tcl_NewStringObj((char *)proto, (int)len));
#endif

    Tcl_ListObjAppendElement(interp, objPtr,
	Tcl_NewStringObj("version", -1));
    Tcl_ListObjAppendElement(interp, objPtr,
	Tcl_NewStringObj(SSL_get_version(statePtr->ssl), -1));

    Tcl_SetObjResult( interp, objPtr);

        <dt><strong>cipher</strong> <em>cipher</em></dt>
        <dd>The current cipher in use between the client and
            server channels.</dd>
        <dt><strong>sbits</strong> <em>n</em></dt>
        <dd>The number of bits used for the session key.</dd>
        <dt><strong>certificate</strong> <em>n</em></dt>
        <dd>The PEM encoded certificate.</dd>
        <dt><strong>alpn</strong> <em>protocol</em></dt>
        <dd>The protocol selected after Application-Layer Protocol
	    Negotiation (ALPN).</dd>
        <dt><strong>version</strong> <em>value</em></dt>
        <dd>The protocol version used for the connection:
	  SSLv2, SSLv3, TLSv1, TLSv1.1, TLSv1.2, unknown</dd>
    </dl>
</blockquote>

<dl>
    <dt><a name="tls::import"><b>tls::import </b><i>channel
        ?options?</i></a></dt>
    <dd>SSL-enable a regular Tcl channel - it need not be a
        socket, but must provide bi-directional flow. Also
        setting session parameters for SSL handshake.</dd>
</dl>

<blockquote>
    <dl>
        <dt><strong>-alpn</strong> <em>list</em></dt>
        <dd>List of protocols to offer during Application-Layer
	    Protocol Negotiation (ALPN). For example: h2, http/1.1, etc.</dd>
        <dt><strong>-cadir</strong> <em>dir</em></dt>
        <dd>Provide the directory containing the CA certificates.</dd>
        <dt><strong>-cafile </strong><em>filename</em></dt>
        <dd>Provide the CA file.</dd>
        <dt><strong>-certfile</strong> <em>filename</em></dt>
        <dd>Provide the name of a file containing certificate to use.</dd>
        <dt><strong>-cert</strong> <em>filename</em></dt>

        {* -key iopts 1}
        {* -keyfile iopts 1}
        {* -password iopts 1}
        {* -request iopts 1}
        {* -require iopts 1}
        {* -autoservername discardOpts 1}
        {* -servername iopts 1}
        {* -alpn iopts 1}
        {* -ssl2 iopts 1}
        {* -ssl3 iopts 1}
        {* -tls1 iopts 1}
        {* -tls1.1 iopts 1}
        {* -tls1.2 iopts 1}
        {* -tls1.3 iopts 1}
    }