static Tcl_Mutex *locks = NULL;
static int locksCount = 0;
static Tcl_Mutex init_mx;
#endif /* OPENSSL_THREADS */
#endif /* TCL_THREADS */


/********************/
/* Callbacks        */
/********************/

/*
 *-------------------------------------------------------------------
 *
 * Eval Callback Command --
 *
 *	Eval callback command and catch any errors
 *
 * Results:
 *	0 = Command returned fail or eval returned TCL_ERROR
 *	1 = Command returned success or eval returned TCL_OK
 *
 * Side effects:
 *	Evaluates callback command
 *
 *-------------------------------------------------------------------
 */
static int
EvalCallback(Tcl_Interp *interp, State *statePtr, Tcl_Obj *cmdPtr) {
    int code, ok;

    Tcl_Preserve((ClientData) interp);
    Tcl_Preserve((ClientData) statePtr);

    /* Eval callback with success for ok or return value 1, fail for error or return value 0 */
    code = Tcl_EvalObjEx(interp, cmdPtr, TCL_EVAL_GLOBAL);
    if (code == TCL_OK) {
	/* Check result for return value */
	Tcl_Obj *result = Tcl_GetObjResult(interp);
	if (result == NULL || Tcl_GetIntFromObj(interp, result, &ok) != TCL_OK) {
	    ok = 1;
	}
    } else {
	/* Error - reject the certificate */
	ok = 0;
#if (TCL_MAJOR_VERSION == 8) && (TCL_MINOR_VERSION < 6)
	Tcl_BackgroundError(interp);
#else
	Tcl_BackgroundException(interp, code);
#endif
    }

    Tcl_Release((ClientData) statePtr);
    Tcl_Release((ClientData) interp);
    return ok;
}

/*
 *-------------------------------------------------------------------
 *
 * InfoCallback --
 *
 *	monitors SSL connection process
 *	Monitors SSL connection process
 *
 * Results:
 *	None
 *
 * Side effects:
 *	Calls callback (if defined)
 *
 *-------------------------------------------------------------------
 */
static void
InfoCallback(const SSL *ssl, int where, int ret) {
    State *statePtr = (State*)SSL_get_app_data((SSL *)ssl);
    Tcl_Interp *interp	= statePtr->interp;
    Tcl_Obj *cmdPtr;
    char *major; char *minor;

    dprintf("Called");

    if (statePtr->callback == (Tcl_Obj*)NULL)
	return;

    cmdPtr = Tcl_DuplicateObj(statePtr->callback);

#if 0
    if (where & SSL_CB_ALERT) {
	sev = SSL_alert_type_string_long(ret);
	if (strcmp(sev, "fatal")==0) {	/* Map to error */
	    Tls_Error(statePtr, SSL_ERROR(ssl, 0));
	    return;
	}
    }
#endif
    if (where & SSL_CB_HANDSHAKE_START) {
	major = "handshake";
	minor = "start";
    } else if (where & SSL_CB_HANDSHAKE_DONE) {
	major = "handshake";
	minor = "done";
    } else {
	if (where & SSL_CB_ALERT)		major = "alert";
	else if (where & SSL_ST_CONNECT)	major = "connect";
	else if (where & SSL_ST_ACCEPT)		major = "accept";
	else					major = "unknown";

	if (where & SSL_CB_READ)		minor = "read";
	else if (where & SSL_CB_WRITE)		minor = "write";
	else if (where & SSL_CB_LOOP)		minor = "loop";
	else if (where & SSL_CB_EXIT)		minor = "exit";
	else					minor = "unknown";
    }

    /* Create command to eval */
    cmdPtr = Tcl_DuplicateObj(statePtr->callback);
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj("info", -1));
    Tcl_ListObjAppendElement(interp, cmdPtr,
	    Tcl_NewStringObj(Tcl_GetChannelName(statePtr->self), -1));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj(major, -1));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj(minor, -1));

    if (where & (SSL_CB_LOOP|SSL_CB_EXIT)) {
    if (where & SSL_CB_ALERT) {
	Tcl_ListObjAppendElement(interp, cmdPtr,
	    Tcl_NewStringObj(SSL_state_string_long(ssl), -1));
    } else if (where & SSL_CB_ALERT) {
	const char *cp = (char *) SSL_alert_desc_string_long(ret);
	    Tcl_NewStringObj(SSL_alert_desc_string_long(ret), -1));

	Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj(cp, -1));
	Tcl_ListObjAppendElement(interp, cmdPtr,
	    Tcl_NewStringObj(SSL_alert_type_string_long(ret), -1));
    } else {
	Tcl_ListObjAppendElement(interp, cmdPtr,
	    Tcl_NewStringObj(SSL_state_string_long(ssl), -1));
	Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj("info", -1));
    }
    Tcl_Preserve((ClientData) interp);
    Tcl_Preserve((ClientData) statePtr);

    /* Eval callback command */
    Tcl_IncrRefCount(cmdPtr);
    (void) Tcl_EvalObjEx(interp, cmdPtr, TCL_EVAL_GLOBAL);
    EvalCallback(interp, statePtr, cmdPtr);
    Tcl_DecrRefCount(cmdPtr);

    Tcl_Release((ClientData) statePtr);
    Tcl_Release((ClientData) interp);
}

/*
 *-------------------------------------------------------------------
 *
 * MessageCallback --
 *
 *	Monitors SSL protocol messages
 *
 * Results:
 *	None
 *
 * Side effects:
 *	Calls callback (if defined)
 *
 *-------------------------------------------------------------------
 */
#ifndef OPENSSL_NO_SSL_TRACE
static void
MessageCallback(int write_p, int version, int content_type, const void *buf, size_t len, SSL *ssl, void *arg) {
    State *statePtr = (State*)arg;
    Tcl_Interp *interp	= statePtr->interp;
    Tcl_Obj *cmdPtr;
    char *ver, *type;
    BIO *bio;
    char buffer[15000];
    buffer[0] = 0;

    dprintf("Called");

    if (statePtr->callback == (Tcl_Obj*)NULL)
	return;

    switch(version) {
#if OPENSSL_VERSION_NUMBER < 0x10100000L && !defined(NO_SSL2) && !defined(OPENSSL_NO_SSL2)
    case SSL2_VERSION:
	ver = "SSLv2";
	break;
#endif
#if !defined(NO_SSL3) && !defined(OPENSSL_NO_SSL3)
    case SSL3_VERSION:
	ver = "SSLv3";
	break;
#endif
    case TLS1_VERSION:
	ver = "TLSv1";
	break;
    case TLS1_1_VERSION:
	ver = "TLSv1.1";
	break;
    case TLS1_2_VERSION:
	ver = "TLSv1.2";
	break;
    case TLS1_3_VERSION:
	ver = "TLSv1.3";
	break;
    case 0:
        ver = "none";
	break;
    default:
	ver = "unknown";
	break;
    }

    switch (content_type) {
    case SSL3_RT_HEADER:
	type = "Header";
        break;
    case SSL3_RT_INNER_CONTENT_TYPE:
	type = "Inner Content Type";
        break;
    case SSL3_RT_CHANGE_CIPHER_SPEC:
	type = "Change Cipher";
        break;
    case SSL3_RT_ALERT:
	type = "Alert";
        break;
    case SSL3_RT_HANDSHAKE:
	type = "Handshake";
        break;
    case SSL3_RT_APPLICATION_DATA:
	type = "App Data";
        break;
    case DTLS1_RT_HEARTBEAT:
	type = "Heartbeat";
        break;
    default:
	type = "unknown";
    }

    /* Needs compile time option "enable-ssl-trace". */
    if ((bio = BIO_new(BIO_s_mem())) != NULL) {
	int n;
	SSL_trace(write_p, version, content_type, buf, len, ssl, (void *)bio);
	n = BIO_read(bio, buffer, min(BIO_pending(bio), 14999));
	n = (n<0) ? 0 : n;
	buffer[n] = 0;
	(void)BIO_flush(bio);
 	BIO_free(bio);
   }

    /* Create command to eval */
    cmdPtr = Tcl_DuplicateObj(statePtr->callback);
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj("message", -1));
    Tcl_ListObjAppendElement(interp, cmdPtr,
	    Tcl_NewStringObj(Tcl_GetChannelName(statePtr->self), -1));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj(write_p ? "Sent" : "Received", -1));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj(ver, -1));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj(type, -1));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj(buffer, -1));

    /* Eval callback command */
    Tcl_IncrRefCount(cmdPtr);
    EvalCallback(interp, statePtr, cmdPtr);
    Tcl_DecrRefCount(cmdPtr);
}
#endif

/*
 *-------------------------------------------------------------------
 *
 * VerifyCallback --
 *
 *	Monitors SSL certificate validation process.
 *	This is called whenever a certificate is inspected
 *	or decided invalid.
 *	Monitors SSL certificate validation process. Used to control the
 *	behavior when the SSL_VERIFY_PEER flag is set. This is called
 *	whenever a certificate is inspected or decided invalid. Called for
 *	each certificate in the cert chain.
 *
 * Checks:
 *	certificate chain is checked starting with the deepest nesting level
 *	  (the root CA certificate) and worked upward to the peer's certificate.
 *	All signatures are valid, current time is within first and last validity time.
 *	Check that the certificate is issued by the issuer certificate issuer.
 *	Check the revocation status for each certificate.
 *	Check the validity of the given CRL and the cert revocation status.
 *	Check the policies of all the certificates
 *
 * Args
 *	preverify_ok indicates whether the certificate verification passed (1) or not (0)
 *
 * Results:
 *	A callback bound to the socket may return one of:
 *	    0			- the certificate is deemed invalid
 *	    1			- the certificate is deemed valid
 *	    0			- the certificate is deemed invalid, send verification
 *				  failure alert to peer, and terminate handshake.
 *	    1			- the certificate is deemed valid, continue with handshake.
 *	    empty string	- no change to certificate validation
 *
 * Side effects:
 *	The err field of the currently operative State is set
 *	  to a string describing the SSL negotiation failure reason
 *
 *-------------------------------------------------------------------
 */
static int
VerifyCallback(int ok, X509_STORE_CTX *ctx) {
    Tcl_Obj *cmdPtr, *result;
    Tcl_Obj *cmdPtr;
    char *string;
    int length;
    SSL   *ssl		= (SSL*)X509_STORE_CTX_get_ex_data(ctx, SSL_get_ex_data_X509_STORE_CTX_idx());
    X509  *cert		= X509_STORE_CTX_get_current_cert(ctx);
    State *statePtr	= (State*)SSL_get_app_data(ssl);
    Tcl_Interp *interp	= statePtr->interp;
    int depth		= X509_STORE_CTX_get_error_depth(ctx);
    int err		= X509_STORE_CTX_get_error(ctx);
    int code;

    dprintf("Verify: %d", ok);

    if (statePtr->callback == (Tcl_Obj*)NULL) {
    if (statePtr->vcmd == (Tcl_Obj*)NULL) {
	if (statePtr->vflags & SSL_VERIFY_FAIL_IF_NO_PEER_CERT) {
	    return ok;
	} else {
	    return 1;
	}
    }

    /* Create command to eval */
    cmdPtr = Tcl_DuplicateObj(statePtr->callback);
    cmdPtr = Tcl_DuplicateObj(statePtr->vcmd);
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj("verify", -1));
    Tcl_ListObjAppendElement(interp, cmdPtr,
	Tcl_NewStringObj(Tcl_GetChannelName(statePtr->self), -1));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewIntObj(depth));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tls_NewX509Obj(interp, cert));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewIntObj(ok));
    Tcl_ListObjAppendElement(interp, cmdPtr,
	Tcl_NewStringObj((char*)X509_verify_cert_error_string(err), -1));

    Tcl_Preserve((ClientData) interp);
    Tcl_Preserve((ClientData) statePtr);

    statePtr->flags |= TLS_TCL_CALLBACK;
    /* Prevent I/O while callback is in progress */
    /* statePtr->flags |= TLS_TCL_CALLBACK; */

    /* Eval callback command */
    Tcl_IncrRefCount(cmdPtr);
    code = Tcl_EvalObjEx(interp, cmdPtr, TCL_EVAL_GLOBAL);
    if (code != TCL_OK) {
	/* It got an error - reject the certificate.		*/
#if (TCL_MAJOR_VERSION == 8) && (TCL_MINOR_VERSION < 6)
	Tcl_BackgroundError(interp);
#else
	Tcl_BackgroundException(interp, code);
    ok = EvalCallback(interp, statePtr, cmdPtr);
#endif
	ok = 0;
    } else {
	result = Tcl_GetObjResult(interp);
	string = Tcl_GetStringFromObj(result, &length);
	/* An empty result leaves verification unchanged.	*/
	if (string != NULL && length > 0) {
	    code = Tcl_GetIntFromObj(interp, result, &ok);
	    if (code != TCL_OK) {
#if (TCL_MAJOR_VERSION == 8) && (TCL_MINOR_VERSION < 6)
		Tcl_BackgroundError(interp);
#else
		Tcl_BackgroundException(interp, code);
#endif
		ok = 0;
	    }
	}
    }
    Tcl_DecrRefCount(cmdPtr);

    statePtr->flags &= ~(TLS_TCL_CALLBACK);
    /* statePtr->flags &= ~(TLS_TCL_CALLBACK); */

    Tcl_Release((ClientData) statePtr);
    Tcl_Release((ClientData) interp);
    return(ok);	/* By default, leave verification unchanged.	*/
    return(ok);	/* By default, leave verification unchanged. */
}

/*
 *-------------------------------------------------------------------
 *
 * Tls_Error --
 *
 *	Calls callback with $fd and $msg - so the callback can decide
 *	Calls callback with list of errors.
 *	what to do with errors.
 *
 * Side effects:
 *	The err field of the currently operative State is set
 *	  to a string describing the SSL negotiation failure reason
 *
 *-------------------------------------------------------------------
 */
void
Tls_Error(State *statePtr, char *msg) {
    Tcl_Interp *interp	= statePtr->interp;
    Tcl_Obj *cmdPtr;
    int code;
    Tcl_Obj *cmdPtr, *listPtr;
    unsigned long err;
    statePtr->err = msg;

    dprintf("Called");

    if (msg && *msg) {
	Tcl_SetErrorCode(interp, "SSL", msg, (char *)NULL);
    } else {
	msg = Tcl_GetStringFromObj(Tcl_GetObjResult(interp), NULL);
    }
    statePtr->err = msg;

    if (statePtr->callback == (Tcl_Obj*)NULL) {
    if (statePtr->callback == (Tcl_Obj*)NULL)
	char buf[BUFSIZ];
	sprintf(buf, "SSL channel \"%s\": error: %s",
	    Tcl_GetChannelName(statePtr->self), msg);
	Tcl_SetResult(interp, buf, TCL_VOLATILE);
#if (TCL_MAJOR_VERSION == 8) && (TCL_MINOR_VERSION < 6)
	Tcl_BackgroundError(interp);
#else
	Tcl_BackgroundException(interp, TCL_ERROR);
#endif
	return;
    }

    /* Create command to eval */
    cmdPtr = Tcl_DuplicateObj(statePtr->callback);

    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj("error", -1));
    Tcl_ListObjAppendElement(interp, cmdPtr,
	    Tcl_NewStringObj(Tcl_GetChannelName(statePtr->self), -1));
    if (msg != NULL) {
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj(msg, -1));
	Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj(msg, -1));

    Tcl_Preserve((ClientData) interp);
    Tcl_Preserve((ClientData) statePtr);
    } else if ((msg = Tcl_GetStringFromObj(Tcl_GetObjResult(interp), NULL)) != NULL) {
	Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj(msg, -1));

    Tcl_IncrRefCount(cmdPtr);
    code = Tcl_EvalObjEx(interp, cmdPtr, TCL_EVAL_GLOBAL);
    if (code != TCL_OK) {
#if (TCL_MAJOR_VERSION == 8) && (TCL_MINOR_VERSION < 6)
	Tcl_BackgroundError(interp);
#else
	Tcl_BackgroundException(interp, code);
#endif
    } else {
	listPtr = Tcl_NewListObj(0, NULL);
	while ((err = ERR_get_error()) != 0) {
	    Tcl_ListObjAppendElement(interp, listPtr, Tcl_NewStringObj(ERR_reason_error_string(err), -1));
	}
	Tcl_ListObjAppendElement(interp, cmdPtr, listPtr);
    }

    /* Eval callback command */
    Tcl_DecrRefCount(cmdPtr);
    Tcl_Release((ClientData) statePtr);
    Tcl_Release((ClientData) interp);
    Tcl_IncrRefCount(cmdPtr);
    EvalCallback(interp, statePtr, cmdPtr);
    Tcl_DecrRefCount(cmdPtr);
}

/*
 *-------------------------------------------------------------------
 *
 * KeyLogCallback --
 *
 *	Write received key data to log file.
 *
 * Side effects:
 *	none
 *
 *-------------------------------------------------------------------
 */
void KeyLogCallback(const SSL *ssl, const char *line) {
    char *str = getenv(SSLKEYLOGFILE);
    FILE *fd;

    dprintf("Called");

    if (str) {
	fd = fopen(str, "a");
	fprintf(fd, "%s\n",line);
	fclose(fd);
    }
}

/*
 *-------------------------------------------------------------------
 *
 * Password Callback --
 *
 *	Called when a password is needed to unpack RSA and PEM keys.
 *	Evals any bound password script and returns the result as
 *	the password string.
 *
 *-------------------------------------------------------------------
 */
static int
PasswordCallback(char *buf, int size, int verify, void *udata) {
    State *statePtr	= (State *) udata;
    Tcl_Interp *interp	= statePtr->interp;
    Tcl_Obj *cmdPtr;
    int code;

    dprintf("Called");

    /* If no callback, use default callback */
    if (statePtr->password == NULL) {
	if (Tcl_EvalEx(interp, "tls::password", -1, TCL_EVAL_GLOBAL) == TCL_OK) {
	    char *ret = (char *) Tcl_GetStringResult(interp);
	    strncpy(buf, ret, (size_t) size);
	    return (int)strlen(ret);
	} else {
	    return -1;
	}
    }

    /* Create command to eval */
    cmdPtr = Tcl_DuplicateObj(statePtr->password);

    Tcl_Preserve((ClientData) interp);
    Tcl_Preserve((ClientData) statePtr);

    /* Eval callback and success for ok, abort for error, continue for continue */
    Tcl_IncrRefCount(cmdPtr);
    code = Tcl_EvalObjEx(interp, cmdPtr, TCL_EVAL_GLOBAL);
    if (code != TCL_OK) {
#if (TCL_MAJOR_VERSION == 8) && (TCL_MINOR_VERSION < 6)
	Tcl_BackgroundError(interp);
#else
	Tcl_BackgroundException(interp, code);

static int
SessionCallback(const SSL *ssl, SSL_SESSION *session) {
    State *statePtr = (State*)SSL_get_app_data((SSL *)ssl);
    Tcl_Interp *interp	= statePtr->interp;
    Tcl_Obj *cmdPtr;
    const unsigned char *ticket;
    const unsigned char *session_id;
    int code;
    size_t len2;
    unsigned int ulen;

    dprintf("Called");

    if (statePtr->callback == (Tcl_Obj*)NULL) {
	return SSL_TLSEXT_ERR_OK;
    } else if (ssl == NULL) {
	return SSL_TLSEXT_ERR_NOACK;
    }

    /* Create command to eval */
    cmdPtr = Tcl_DuplicateObj(statePtr->callback);
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj("session", -1));

    /* Session id */
    session_id = SSL_SESSION_get_id(session, &ulen);
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewByteArrayObj(session_id, (int) ulen));

    /* Session ticket */
    SSL_SESSION_get0_ticket(session, &ticket, &len2);
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewByteArrayObj(ticket, (int) len2));

    /* Lifetime - number of seconds */
    Tcl_ListObjAppendElement(interp, cmdPtr,
	Tcl_NewLongObj((long) SSL_SESSION_get_ticket_lifetime_hint(session)));

    Tcl_Preserve((ClientData) interp);
    Tcl_Preserve((ClientData) statePtr);

    /* Eval callback command */
    Tcl_IncrRefCount(cmdPtr);
    code = Tcl_EvalObjEx(interp, cmdPtr, TCL_EVAL_GLOBAL);
    if (code != TCL_OK) {
#if (TCL_MAJOR_VERSION == 8) && (TCL_MINOR_VERSION < 6)
	Tcl_BackgroundError(interp);
#else
	Tcl_BackgroundException(interp, code);
    EvalCallback(interp, statePtr, cmdPtr);
#endif
    }
    Tcl_DecrRefCount(cmdPtr);

    return 0;
    Tcl_Release((ClientData) statePtr);
    Tcl_Release((ClientData) interp);    return 0;
}

/*
 *-------------------------------------------------------------------
 *
 * ALPN Callback for Servers --
 * ALPN Callback for Servers and NPN Callback for Clients --
 *
 *	Perform server-side protocol (http/1.1, h2, h3, etc.) selection for the
 *	incoming connection. Called after Hello and server callbacks
 *	Perform protocol (http/1.1, h2, h3, etc.) selection for the
 *	incoming connection. Called after Hello and server callbacks.
 *	Where 'out' is selected protocol and 'in' is the peer advertised list.
 *
 * Results:
 *	None
 *
 * Side effects:
 *	Calls callback (if defined)
 *

    State *statePtr = (State*)arg;
    Tcl_Interp *interp	= statePtr->interp;
    Tcl_Obj *cmdPtr;
    int code, res;

    dprintf("Called");

    if (statePtr->callback == (Tcl_Obj*)NULL) {
	return SSL_TLSEXT_ERR_OK;
    } else if (ssl == NULL) {
    if (ssl == NULL || arg == NULL) {
	return SSL_TLSEXT_ERR_NOACK;
    }

    /* Select protocol */
    if (SSL_select_next_proto(out, outlen, statePtr->protos, statePtr->protos_len,
	in, inlen) == OPENSSL_NPN_NEGOTIATED) {
	/* Match found */
	res = SSL_TLSEXT_ERR_OK;
    } else {
	/* No overlap, so first client protocol used */
	/* OPENSSL_NPN_NO_OVERLAP = No overlap, so use first item from client protocol list */
	res = SSL_TLSEXT_ERR_NOACK;
    }

    if (statePtr->vcmd == (Tcl_Obj*)NULL) {
	return res;
    }

    /* Create command to eval */
    cmdPtr = Tcl_DuplicateObj(statePtr->callback);
    cmdPtr = Tcl_DuplicateObj(statePtr->vcmd);
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj("alpn", -1));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj(*out, -1));

    Tcl_Preserve((ClientData) interp);
    Tcl_Preserve((ClientData) statePtr);

    /* Eval callback command */
    Tcl_IncrRefCount(cmdPtr);
    code = Tcl_EvalObjEx(interp, cmdPtr, TCL_EVAL_GLOBAL);
    if (code != TCL_OK) {
    if ((code = EvalCallback(interp, statePtr, cmdPtr)) > 1) {
	res = SSL_TLSEXT_ERR_NOACK;
    } else if (code == 1) {
#if (TCL_MAJOR_VERSION == 8) && (TCL_MINOR_VERSION < 6)
	Tcl_BackgroundError(interp);
#else
	res = SSL_TLSEXT_ERR_OK;
    } else {
	Tcl_BackgroundException(interp, code);
#endif
	res = SSL_TLSEXT_ERR_ALERT_FATAL;
    }
    Tcl_DecrRefCount(cmdPtr);

    Tcl_Release((ClientData) statePtr);
    Tcl_Release((ClientData) interp);
    return res;
}

/*
 *-------------------------------------------------------------------
 *
 * Advertise Protocols Callback for Next Protocol Negotiation (NPN) in ServerHello --
 *
 *	called when a TLS server needs a list of supported protocols for Next
 *	Protocol Negotiation.
 *
 * Results:
 *	None
 *
 * Side effects:
 *
 * Return codes:
 *	SSL_TLSEXT_ERR_OK: NPN protocol selected. The connection continues.
 *	SSL_TLSEXT_ERR_NOACK: NPN protocol not selected. The connection continues.
 *
 *-------------------------------------------------------------------
 */
#ifdef USE_NPN
static int
NPNCallback(const SSL *ssl, const unsigned char **out, unsigned int *outlen, void *arg) {
    State *statePtr = (State*)arg;

    dprintf("Called");

    if (ssl == NULL || arg == NULL) {
	return SSL_TLSEXT_ERR_NOACK;
    }

    /* Set protocols list */
    if (statePtr->protos != NULL) {
	*out = statePtr->protos;
	*outlen = statePtr->protos_len;
    } else {
	*out = NULL;
	*outlen = 0;
	return SSL_TLSEXT_ERR_NOACK;
    }
    return SSL_TLSEXT_ERR_OK;
}
#endif

/*
 *-------------------------------------------------------------------
 *
 * SNI Callback for Servers --
 *
 *	Perform server-side SNI hostname selection after receiving SNI header.
 *	Called after hello callback but before ALPN callback.
 *	Perform server-side SNI hostname selection after receiving SNI extension
 *	in Client Hello. Called after hello callback but before ALPN callback.
 *
 * Results:
 *	None
 *
 * Side effects:
 *	Calls callback (if defined)
 *
 * Return codes:
 *	SSL_TLSEXT_ERR_OK: SNI hostname is accepted. The connection continues.
 *	SSL_TLSEXT_ERR_ALERT_FATAL: SNI hostname is not accepted. The connection
 *	    is aborted. Default for alert is SSL_AD_UNRECOGNIZED_NAME.
 *	SSL_TLSEXT_ERR_ALERT_WARNING: SNI hostname is not accepted, warning alert
 *	    sent (not in TLSv1.3). The connection continues.
 *	    sent (not supported in TLSv1.3). The connection continues.
 *	SSL_TLSEXT_ERR_NOACK: SNI hostname is not accepted and not acknowledged,
 *	    e.g. if SNI has not been configured. The connection continues.
 *
 *-------------------------------------------------------------------
 */
static int
SNICallback(const SSL *ssl, int *alert, void *arg) {
    State *statePtr = (State*)arg;
    Tcl_Interp *interp	= statePtr->interp;
    Tcl_Obj *cmdPtr;
    int code;
    int code, res;
    char *servername = NULL;

    dprintf("Called");

    if (statePtr->callback == (Tcl_Obj*)NULL) {
	return SSL_TLSEXT_ERR_OK;
    } else if (ssl == NULL) {
    if (ssl == NULL || arg == NULL) {
	return SSL_TLSEXT_ERR_NOACK;
    }

    /* Only works for TLS 1.2 and earlier */
    servername = SSL_get_servername(ssl, TLSEXT_NAMETYPE_host_name);
    if (!servername || servername[0] == '\0') {
	return SSL_TLSEXT_ERR_NOACK;
    }

    servername = SSL_get_servername(ssl, TLSEXT_NAMETYPE_host_name);
    if (!servername || servername[0] == '\0') {
        return SSL_TLSEXT_ERR_NOACK;
    if (statePtr->vcmd == (Tcl_Obj*)NULL) {
	return SSL_TLSEXT_ERR_OK;
    }

    /* Create command to eval */
    cmdPtr = Tcl_DuplicateObj(statePtr->callback);
    cmdPtr = Tcl_DuplicateObj(statePtr->vcmd);
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj("sni", -1));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj(servername , -1));

    Tcl_Preserve((ClientData) interp);
    Tcl_Preserve((ClientData) statePtr);

    /* Eval callback command */
    Tcl_IncrRefCount(cmdPtr);
    code = Tcl_EvalObjEx(interp, cmdPtr, TCL_EVAL_GLOBAL);
    if (code != TCL_OK) {
#if (TCL_MAJOR_VERSION == 8) && (TCL_MINOR_VERSION < 6)
    if ((code = EvalCallback(interp, statePtr, cmdPtr)) > 1) {
	res = SSL_TLSEXT_ERR_ALERT_WARNING;
	*alert = SSL_AD_UNRECOGNIZED_NAME; /* Not supported by TLS 1.3 */
    } else if (code == 1) {
	res = SSL_TLSEXT_ERR_OK;
	Tcl_BackgroundError(interp);
#else
	Tcl_BackgroundException(interp, code);
    } else {
	res = SSL_TLSEXT_ERR_ALERT_FATAL;
	*alert = SSL_AD_UNRECOGNIZED_NAME; /* Not supported by TLS 1.3 */
#endif
    }
    Tcl_DecrRefCount(cmdPtr);

    Tcl_Release((ClientData) statePtr);
    Tcl_Release((ClientData) interp);
    return SSL_TLSEXT_ERR_OK;
    return res;
}

/*
 *-------------------------------------------------------------------
 *
 * Hello Handshake Callback for Servers --
 * ClientHello Handshake Callback for Servers --
 *
 *	Used by server to examine the server name indication (SNI) extension
 *	provided by the client in order to select an appropriate certificate to
 *	present, and make other configuration adjustments relevant to that server
 *	name and its configuration. This includes swapping out the associated
 *	SSL_CTX pointer, modifying the server's list of permitted TLS versions,
 *	changing the server's cipher list in response to the client's cipher list, etc.
 *	Called before SNI and ALPN callbacks.
 *
 * Results:
 *	None
 *
 * Side effects:
 *	Calls callback (if defined)
 *
 * Return codes:
 *	SSL_CLIENT_HELLO_RETRY = suspend the handshake, and the handshake function will return immediately
 *	SSL_CLIENT_HELLO_ERROR = failure, terminate connection. Set alert to error code.
 *	SSL_CLIENT_HELLO_SUCCESS = success
 *	SSL_CLIENT_HELLO_RETRY: suspend the handshake, and the handshake function will return immediately
 *	SSL_CLIENT_HELLO_ERROR: failure, terminate connection. Set alert to error code.
 *	SSL_CLIENT_HELLO_SUCCESS: success
 *
 *-------------------------------------------------------------------
 */
static int
HelloCallback(const SSL *ssl, int *alert, void *arg) {
    State *statePtr = (State*)arg;
    Tcl_Interp *interp	= statePtr->interp;
    Tcl_Obj *cmdPtr;
    int code;
    int code, res;
    const char *servername;
    const unsigned char *p;
    size_t len, remaining;

    dprintf("Called");

    if (statePtr->callback == (Tcl_Obj*)NULL) {
    if (statePtr->vcmd == (Tcl_Obj*)NULL) {
	return SSL_CLIENT_HELLO_SUCCESS;
    } else if (ssl == NULL) {
    } else if (ssl == NULL || arg == NULL) {
	return SSL_CLIENT_HELLO_ERROR;
    }

    /* Get names */
    if (!SSL_client_hello_get0_ext(ssl, TLSEXT_TYPE_server_name, &p, &remaining) || remaining <= 2) {
	*alert = SSL_R_SSLV3_ALERT_ILLEGAL_PARAMETER;
        return SSL_CLIENT_HELLO_ERROR;
	return SSL_CLIENT_HELLO_ERROR;
    }

    /* Extract the length of the supplied list of names. */
    len = (*(p++) << 8);
    len += *(p++);
    if (len + 2 != remaining) {
	*alert = SSL_R_SSLV3_ALERT_ILLEGAL_PARAMETER;
        return SSL_CLIENT_HELLO_ERROR;
	return SSL_CLIENT_HELLO_ERROR;
    }
    remaining = len;

    /* The list in practice only has a single element, so we only consider the first one. */
    if (remaining == 0 || *p++ != TLSEXT_NAMETYPE_host_name) {
	*alert = SSL_R_TLSV1_ALERT_INTERNAL_ERROR;
        return SSL_CLIENT_HELLO_ERROR;
	return SSL_CLIENT_HELLO_ERROR;
    }
    remaining--;

    /* Now we can finally pull out the byte array with the actual hostname. */
    if (remaining <= 2) {
	*alert = SSL_R_TLSV1_ALERT_INTERNAL_ERROR;
        return SSL_CLIENT_HELLO_ERROR;
	return SSL_CLIENT_HELLO_ERROR;
    }
    len = (*(p++) << 8);
    len += *(p++);
    if (len + 2 > remaining) {
	*alert = SSL_R_TLSV1_ALERT_INTERNAL_ERROR;
        return SSL_CLIENT_HELLO_ERROR;
	return SSL_CLIENT_HELLO_ERROR;
    }
    remaining = len;
    servername = (const char *)p;

    /* Create command to eval */
    cmdPtr = Tcl_DuplicateObj(statePtr->callback);
    cmdPtr = Tcl_DuplicateObj(statePtr->vcmd);
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj("hello", -1));
    Tcl_ListObjAppendElement(interp, cmdPtr, Tcl_NewStringObj(servername, (int) len));

    Tcl_Preserve((ClientData) interp);
    Tcl_Preserve((ClientData) statePtr);

    /* Eval callback command */
    Tcl_IncrRefCount(cmdPtr);
    code = Tcl_EvalObjEx(interp, cmdPtr, TCL_EVAL_GLOBAL);
    if (code != TCL_OK) {
#if (TCL_MAJOR_VERSION == 8) && (TCL_MINOR_VERSION < 6)
    if ((code = EvalCallback(interp, statePtr, cmdPtr)) > 1) {
	res = SSL_CLIENT_HELLO_RETRY;
	*alert = SSL_R_TLSV1_ALERT_USER_CANCELLED;
    } else if (code == 1) {
	res = SSL_CLIENT_HELLO_SUCCESS;
	Tcl_BackgroundError(interp);
#else
	Tcl_BackgroundException(interp, code);
    } else {
	res = SSL_CLIENT_HELLO_ERROR;
	*alert = SSL_R_TLSV1_ALERT_INTERNAL_ERROR;
#endif
    }
    Tcl_DecrRefCount(cmdPtr);

    Tcl_Release((ClientData) statePtr);
    Tcl_Release((ClientData) interp);
    return SSL_CLIENT_HELLO_SUCCESS;
    return res;
}

/********************/
/* Commands         */
/********************/

/*

#endif
	case TLS_TLS1_3:
#if defined(NO_TLS1_3) || defined(OPENSSL_NO_TLS1_3)
	    Tcl_AppendResult(interp, protocols[index], ": protocol not supported", NULL);
	    return TCL_ERROR;
#else
	    ctx = SSL_CTX_new(TLS_method());
            SSL_CTX_set_min_proto_version(ctx, TLS1_3_VERSION);
	    SSL_CTX_set_min_proto_version(ctx, TLS1_3_VERSION);
	    SSL_CTX_set_max_proto_version(ctx, TLS1_3_VERSION);
	    break;
#endif
	default:
	    break;
    }
    if (ctx == NULL) {

    dprintf("Called");

    if (objc != 1) {
	Tcl_WrongNumArgs(interp, 1, objv, "");
	return TCL_ERROR;
    }

    ERR_clear_error();

    objPtr = Tcl_NewListObj(0, NULL);

#if OPENSSL_VERSION_NUMBER < 0x10100000L && !defined(NO_SSL2) && !defined(OPENSSL_NO_SSL2)
    Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj(protocols[TLS_SSL2], -1));
#endif
#if !defined(NO_SSL3) && !defined(OPENSSL_NO_SSL3)
#if !defined(NO_SSL3) && !defined(OPENSSL_NO_SSL3) && !defined(OPENSSL_NO_SSL3_METHOD)
    Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj(protocols[TLS_SSL3], -1));
#endif
#if !defined(NO_TLS1) && !defined(OPENSSL_NO_TLS1)
#if !defined(NO_TLS1) && !defined(OPENSSL_NO_TLS1) && !defined(OPENSSL_NO_TLS1_METHOD)
    Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj(protocols[TLS_TLS1], -1));
#endif
#if !defined(NO_TLS1_1) && !defined(OPENSSL_NO_TLS1_1)
#if !defined(NO_TLS1_1) && !defined(OPENSSL_NO_TLS1_1) && !defined(OPENSSL_NO_TLS1_1_METHOD)
    Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj(protocols[TLS_TLS1_1], -1));
#endif
#if !defined(NO_TLS1_2) && !defined(OPENSSL_NO_TLS1_2)
#if !defined(NO_TLS1_2) && !defined(OPENSSL_NO_TLS1_2) && !defined(OPENSSL_NO_TLS1_2_METHOD)
    Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj(protocols[TLS_TLS1_2], -1));
#endif
#if !defined(NO_TLS1_3) && !defined(OPENSSL_NO_TLS1_3)
    Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj(protocols[TLS_TLS1_3], -1));
#endif

    Tcl_SetObjResult(interp, objPtr);

    dprintf("Called");

    if (objc != 2) {
	Tcl_WrongNumArgs(interp, 1, objv, "channel");
	return(TCL_ERROR);
    }

    ERR_clear_error();

    chan = Tcl_GetChannel(interp, Tcl_GetStringFromObj(objv[1], NULL), NULL);
    if (chan == (Tcl_Channel) NULL) {
	return(TCL_ERROR);
    }

    /* Make sure to operate on the topmost channel */
    chan = Tcl_GetTopChannel(chan);
    if (Tcl_GetChannelType(chan) != Tls_ChannelType()) {
	Tcl_AppendResult(interp, "bad channel \"", Tcl_GetChannelName(chan), "\": not a TLS channel", NULL);
	Tcl_AppendResult(interp, "bad channel \"", Tcl_GetChannelName(chan),
	    "\": not a TLS channel", NULL);
	Tcl_SetErrorCode(interp, "TLS", "HANDSHAKE", "CHANNEL", "INVALID", (char *) NULL);
	return(TCL_ERROR);
    }
    statePtr = (State *)Tcl_GetChannelInstanceData(chan);

    dprintf("Calling Tls_WaitForConnect");
    ret = Tls_WaitForConnect(statePtr, &err, 1);
    dprintf("Tls_WaitForConnect returned: %i", ret);

	Tcl_SetErrno(err);

	if (!errStr || (*errStr == 0)) {
	    errStr = Tcl_PosixError(interp);
	}

	Tcl_AppendResult(interp, "handshake failed: ", errStr, (char *) NULL);
	Tcl_SetErrorCode(interp, "TLS", "HANDSHAKE", "FAILED", (char *) NULL);
	dprintf("Returning TCL_ERROR with handshake failed: %s", errStr);
	return(TCL_ERROR);
    } else {
	if (err != 0) {
	    dprintf("Got an error with a completed handshake: err = %i", err);
	}
	ret = 1;

static int
ImportObjCmd(ClientData clientData, Tcl_Interp *interp, int objc, Tcl_Obj *const objv[]) {
    Tcl_Channel chan;		/* The channel to set a mode on. */
    State *statePtr;		/* client state for ssl socket */
    SSL_CTX *ctx	        = NULL;
    Tcl_Obj *script	        = NULL;
    Tcl_Obj *password	        = NULL;
    Tcl_Obj *vcmd	        = NULL;
    Tcl_DString upperChannelTranslation, upperChannelBlocking, upperChannelEncoding, upperChannelEOFChar;
    int idx, len;
    int flags		        = TLS_TCL_INIT;
    int server		        = 0;	/* is connection incoming or outgoing? */
    char *keyfile	        = NULL;
    char *certfile	        = NULL;
    unsigned char *key  	= NULL;

    tls1_3 = 0;
#endif

    if (objc < 2) {
	Tcl_WrongNumArgs(interp, 1, objv, "channel ?options?");
	return TCL_ERROR;
    }

    ERR_clear_error();

    chan = Tcl_GetChannel(interp, Tcl_GetStringFromObj(objv[1], NULL), NULL);
    if (chan == (Tcl_Channel) NULL) {
	return TCL_ERROR;
    }

    /* Make sure to operate on the topmost channel */
    chan = Tcl_GetTopChannel(chan);

    for (idx = 2; idx < objc; idx++) {
	char *opt = Tcl_GetStringFromObj(objv[idx], NULL);

	if (opt[0] != '-')
	    break;

	OPTOBJ("-alpn", alpn);
	OPTSTR("-cadir", CAdir);
	OPTSTR("-cafile", CAfile);
	OPTBYTE("-cert", cert, cert_len);
	OPTSTR("-certfile", certfile);
	OPTSTR("-cipher", ciphers);
	OPTSTR("-ciphers", ciphers);
	OPTSTR("-ciphersuites", ciphersuites);
	OPTOBJ("-command", script);
	OPTSTR("-dhparams", DHparams);
	OPTBYTE("-key", key, key_len);
	OPTSTR("-keyfile", keyfile);
	OPTSTR("-model", model);
	OPTOBJ("-password", password);
	OPTBOOL("-post_handshake", post_handshake);
	OPTBOOL("-require", require);
	OPTBOOL("-request", request);
	OPTBOOL("-require", require);
	OPTINT("-securitylevel", level);
	OPTBOOL("-server", server);
	OPTSTR("-servername", servername);
	OPTSTR("-session_id", session_id);
	OPTOBJ("-alpn", alpn);
	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);
	OPTOBJ("-validatecommand", vcmd);
	OPTOBJ("-vcmd", vcmd);

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

	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 (request && post_handshake)  verify |= SSL_VERIFY_POST_HANDSHAKE;
    if (verify == 0)	verify = SSL_VERIFY_NONE;
    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 (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);
    proto |= (tls1_3 ? TLS_PROTO_TLS1_3 : 0);

    if (password) {
	(void) Tcl_GetStringFromObj(password, &len);
	if (len) {
	    statePtr->password = password;
	    Tcl_IncrRefCount(statePtr->password);
	}
    }

    /* allocate validate command */
    if (vcmd) {
	(void) Tcl_GetStringFromObj(vcmd, &len);
	if (len) {
	    statePtr->vcmd = vcmd;
	    Tcl_IncrRefCount(statePtr->vcmd);
	}
    }

    if (model != NULL) {
	int mode;
	/* Get the "model" context */
	chan = Tcl_GetChannel(interp, model, &mode);
	if (chan == (Tcl_Channel) NULL) {
	    Tls_Free((char *) statePtr);
	    return TCL_ERROR;
	}

	/*
	 * Make sure to operate on the topmost channel
	 */
	chan = Tcl_GetTopChannel(chan);
	if (Tcl_GetChannelType(chan) != Tls_ChannelType()) {
	    Tcl_AppendResult(interp, "bad channel \"", Tcl_GetChannelName(chan),
		"\": not a TLS channel", NULL);
	    Tcl_SetErrorCode(interp, "TLS", "IMPORT", "CHANNEL", "INVALID", (char *) NULL);
	    Tls_Free((char *) statePtr);
	    return TCL_ERROR;
	}
	ctx = ((State *)Tcl_GetChannelInstanceData(chan))->ctx;
    } else {
	if ((ctx = CTX_Init(statePtr, server, proto, keyfile, certfile, key, cert, key_len,
	    cert_len, CAdir, CAfile, ciphers, ciphersuites, level, DHparams)) == NULL) {

    /*
     * SSL Initialization
     */
    statePtr->ssl = SSL_new(statePtr->ctx);
    if (!statePtr->ssl) {
	/* SSL library error */
	Tcl_AppendResult(interp, "couldn't construct ssl session: ", REASON(), (char *) NULL);
	    Tcl_SetErrorCode(interp, "TLS", "IMPORT", "INIT", "FAILED", (char *) NULL);
	Tls_Free((char *) statePtr);
	return TCL_ERROR;
    }

    /* Set host server name */
    if (servername) {
	/* Sets the server name indication (SNI) ClientHello extension */
	/* Sets the server name indication (SNI) in ClientHello extension */
	/* Per RFC 6066, hostname is a ASCII encoded string. */
	if (!SSL_set_tlsext_host_name(statePtr->ssl, servername) && require) {
	    Tcl_AppendResult(interp, "setting TLS host name extension failed", (char *) NULL);
	    Tcl_SetErrorCode(interp, "TLS", "IMPORT", "SNI", "FAILED", (char *) NULL);
            Tls_Free((char *) statePtr);
            return TCL_ERROR;
        }
	    Tls_Free((char *) statePtr);
	    return TCL_ERROR;
	}

	/* Configure server host name checks in the SSL client. Set DNS hostname to
	   name for peer certificate checks. SSL_set1_host has limitations. */
	if (!SSL_add1_host(statePtr->ssl, servername)) {
	    Tcl_AppendResult(interp, "setting DNS host name failed", (char *) NULL);
	    Tcl_SetErrorCode(interp, "TLS", "IMPORT", "HOSTNAME", "FAILED", (char *) NULL);
            Tls_Free((char *) statePtr);
            return TCL_ERROR;
	    Tls_Free((char *) statePtr);
	    return TCL_ERROR;
	}
    }

    /* Resume session id */
    if (session_id && strlen(session_id) <= SSL_MAX_SID_CTX_LENGTH) {
	/* SSL_set_session() */
	if (!SSL_SESSION_set1_id_context(SSL_get_session(statePtr->ssl), session_id, (unsigned int) strlen(session_id))) {
	    Tcl_AppendResult(interp, "Resume session id ", session_id, " failed", (char *) NULL);
	    Tcl_SetErrorCode(interp, "TLS", "IMPORT", "SESSION", "FAILED", (char *) NULL);
            Tls_Free((char *) statePtr);
            return TCL_ERROR;
	}
    }

    if (alpn) {
	/* Convert a Tcl list into a protocol-list in wire-format */
	/* Convert a TCL list into a protocol-list in wire-format */
	unsigned char *protos, *p;
	unsigned int protos_len = 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);
		Tcl_SetErrorCode(interp, "TLS", "IMPORT", "ALPN", "FAILED", (char *) NULL);
		Tls_Free((char *) statePtr);
		return TCL_ERROR;
	    }
	    protos_len += 1 + len;
	}

	/* Build the complete protocol-list */
	protos = ckalloc(protos_len);
	/* 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;
	}

	/* SSL_set_alpn_protos makes a copy of the protocol-list */
	/* Note: This functions reverses the return value convention */
	if (SSL_set_alpn_protos(statePtr->ssl, protos, protos_len)) {
	    Tcl_AppendResult(interp, "failed to set ALPN protocols", (char *) NULL);
	    Tcl_SetErrorCode(interp, "TLS", "IMPORT", "ALPN", "FAILED", (char *) NULL);
	    Tls_Free((char *) statePtr);
	    ckfree(protos);
	    return TCL_ERROR;
	}

	/* Store protocols list */
	statePtr->protos = protos;
	statePtr->protos_len = protos_len;
    } else {
	statePtr->protos = NULL;
	statePtr->protos_len = 0;
    }

    /*
     * SSL Callbacks
     */
    SSL_set_app_data(statePtr->ssl, (void *)statePtr);	/* point back to us */
    SSL_set_verify(statePtr->ssl, verify, VerifyCallback);
    SSL_CTX_set_info_callback(statePtr->ctx, InfoCallback);
    SSL_set_info_callback(statePtr->ssl, InfoCallback);

    /* Callback for observing protocol messages */
#ifndef OPENSSL_NO_SSL_TRACE
    /* void SSL_CTX_set_msg_callback_arg(statePtr->ctx, (void *)statePtr);
    void SSL_CTX_set_msg_callback(statePtr->ctx, MessageCallback); */
    SSL_set_msg_callback_arg(statePtr->ssl, (void *)statePtr);
    SSL_set_msg_callback(statePtr->ssl, MessageCallback);
#endif

    /* Create Tcl_Channel BIO Handler */
    statePtr->p_bio	= BIO_new_tcl(statePtr, BIO_NOCLOSE);
    statePtr->bio	= BIO_new(BIO_f_ssl());

    if (server) {
	/* Server callbacks */
	SSL_CTX_set_alpn_select_cb(statePtr->ctx, ALPNCallback, (void *)statePtr);
	SSL_CTX_set_tlsext_servername_arg(statePtr->ctx, (void *)statePtr);
	SSL_CTX_set_tlsext_servername_callback(statePtr->ctx, SNICallback);
	SSL_CTX_set_client_hello_cb(statePtr->ctx, HelloCallback, (void *)statePtr);
	if (statePtr->protos != NULL) {
	    SSL_CTX_set_alpn_select_cb(statePtr->ctx, ALPNCallback, (void *)statePtr);
#ifdef USE_NPN
	    if (tls1_2 == 0 && tls1_3 == 0) {
		SSL_CTX_set_next_protos_advertised_cb(statePtr->ctx, NPNCallback, (void *)statePtr);

	    }
#endif
	}

	/* Enable server to send cert request after handshake (TLS 1.3 only) */
	/* A write operation must take place for the Certificate Request to be
	   sent to the client, this can be done with SSL_do_handshake(). */
	if (request && post_handshake) {
	    SSL_verify_client_post_handshake(statePtr->ssl);
	}

	/* Set server mode */
	statePtr->flags |= TLS_TCL_SERVER;
	SSL_set_accept_state(statePtr->ssl);
    } else {
	/* Client callbacks */
#ifdef USE_NPN
	if (statePtr->protos != NULL && tls1_2 == 0 && tls1_3 == 0) {
	    SSL_CTX_set_next_proto_select_cb(statePtr->ctx, ALPNCallback, (void *)statePtr);
	}
#endif

	/* Session caching */
	SSL_CTX_set_session_cache_mode(statePtr->ctx, SSL_SESS_CACHE_CLIENT | SSL_SESS_CACHE_NO_INTERNAL_STORE);
	SSL_CTX_sess_set_new_cb(statePtr->ctx, SessionCallback);

	/* Enable post handshake Authentication extension. TLS 1.3 only, not http/2. */
	if (request && post_handshake) {
	    SSL_set_post_handshake_auth(statePtr->ssl, 1);
	}

	/* Set client mode */
	SSL_set_connect_state(statePtr->ssl);
    }
    SSL_set_bio(statePtr->ssl, statePtr->p_bio, statePtr->p_bio);
    BIO_set_ssl(statePtr->bio, statePtr->ssl, BIO_NOCLOSE);

    /*
     * End of SSL Init

    /* Make sure to operate on the topmost channel */
    chan = Tcl_GetTopChannel(chan);

    if (Tcl_GetChannelType(chan) != Tls_ChannelType()) {
	Tcl_AppendResult(interp, "bad channel \"", Tcl_GetChannelName(chan),
		"\": not a TLS channel", NULL);
	    Tcl_SetErrorCode(interp, "TLS", "UNIMPORT", "CHANNEL", "INVALID", (char *) NULL);
	return TCL_ERROR;
    }

    if (Tcl_UnstackChannel(interp, chan) == TCL_ERROR) {
	return TCL_ERROR;
    }

#if !defined(NO_TLS1_3) && !defined(OPENSSL_NO_TLS1_3)
	off |= (ENABLED(proto, TLS_PROTO_TLS1_3) ? 0 : SSL_OP_NO_TLSv1_3);
#endif
	break;
    }

    ERR_clear_error();
    ctx = SSL_CTX_new(method);

    ctx = SSL_CTX_new(method);
    if (!ctx) {
	return(NULL);
    }

    if (getenv(SSLKEYLOGFILE)) {
	SSL_CTX_set_keylog_callback(ctx, KeyLogCallback);
    }

	SSL_CTX_set_options(ctx, SSL_OP_CIPHER_SERVER_PREFERENCE);
    }

    SSL_CTX_set_app_data(ctx, (void*)interp);	/* remember the interpreter */
    SSL_CTX_set_options(ctx, SSL_OP_ALL);	/* all SSL bug workarounds */
    SSL_CTX_set_options(ctx, off);		/* disable protocol versions */
#if OPENSSL_VERSION_NUMBER < 0x10101000L
    SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);	/* handle new handshakes in background */
    SSL_CTX_set_mode(ctx, SSL_MODE_AUTO_RETRY);	/* handle new handshakes in background. On by default in OpenSSL 1.1.1. */
#endif
    SSL_CTX_sess_set_cache_size(ctx, 128);

    /* Set user defined ciphers, cipher suites, and security level */
    if ((ciphers != NULL) && !SSL_CTX_set_cipher_list(ctx, ciphers)) {
	    Tcl_AppendResult(interp, "Set ciphers failed: No valid ciphers", (char *) NULL);
	    SSL_CTX_free(ctx);
	    return NULL;
	Tcl_AppendResult(interp, "Set ciphers failed: No valid ciphers", (char *) NULL);
	SSL_CTX_free(ctx);
	return NULL;
    }
    if ((ciphersuites != NULL) && !SSL_CTX_set_ciphersuites(ctx, ciphersuites)) {
	    Tcl_AppendResult(interp, "Set cipher suites failed: No valid ciphers", (char *) NULL);
	    SSL_CTX_free(ctx);
	    return NULL;
	Tcl_AppendResult(interp, "Set cipher suites failed: No valid ciphers", (char *) NULL);
	SSL_CTX_free(ctx);
	return NULL;
    }

    /* Set security level */
    if (level > -1 && level < 6) {
	/* SSL_set_security_level */
	SSL_CTX_set_security_level(ctx, level);
    }

	return TCL_ERROR;
    }
    /* Make sure to operate on the topmost channel */
    chan = Tcl_GetTopChannel(chan);
    if (Tcl_GetChannelType(chan) != Tls_ChannelType()) {
	Tcl_AppendResult(interp, "bad channel \"", Tcl_GetChannelName(chan),
		"\": not a TLS channel", NULL);
	Tcl_SetErrorCode(interp, "TLS", "STATUS", "CHANNEL", "INVALID", (char *) NULL);
	return TCL_ERROR;
    }
    statePtr = (State *) Tcl_GetChannelInstanceData(chan);

    /* Get certificate for peer or self */
    if (objc == 2) {
	peer = SSL_get_peer_certificate(statePtr->ssl);
    } else {
	peer = SSL_get_certificate(statePtr->ssl);
    }
    if (peer) {
	objPtr = Tls_NewX509Obj(interp, peer);
	if (objc == 2) { X509_free(peer); }
    } else {
	objPtr = Tcl_NewListObj(0, NULL);
    }

    /* Peer cert chain (client only) */
    STACK_OF(X509)* ssl_certs = SSL_get_peer_cert_chain(statePtr->ssl);
    if (!peer && (ssl_certs == NULL || sk_X509_num(ssl_certs) == 0)) {
	Tcl_SetErrorCode(interp, "TLS", "STATUS", "CERTIFICATE", (char *) NULL);
	return TCL_ERROR;
    }

    /* Peer name from cert */
    Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("peername", -1));
    Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj(SSL_get0_peername(statePtr->ssl), -1));

    Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("sbits", -1));
    Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewIntObj(SSL_get_cipher_bits(statePtr->ssl, 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));
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj(ciphers, -1));
    }

    /* Verify the X509 certificate presented by the peer */
    Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("verification", -1));
    Tcl_ListObjAppendElement(interp, objPtr,
	Tcl_NewStringObj(X509_verify_cert_error_string(SSL_get_verify_result(statePtr->ssl)), -1));

    if (chan == (Tcl_Channel) NULL) {
	return(TCL_ERROR);
    }

    /* Make sure to operate on the topmost channel */
    chan = Tcl_GetTopChannel(chan);
    if (Tcl_GetChannelType(chan) != Tls_ChannelType()) {
	Tcl_AppendResult(interp, "bad channel \"", Tcl_GetChannelName(chan), "\": not a TLS channel", NULL);
	Tcl_AppendResult(interp, "bad channel \"", Tcl_GetChannelName(chan),
	    "\": not a TLS channel", NULL);
	Tcl_SetErrorCode(interp, "TLS", "CONNECTION", "CHANNEL", "INVALID", (char *) NULL);
	return(TCL_ERROR);
    }

    objPtr = Tcl_NewListObj(0, NULL);

    /* Connection info */
    statePtr = (State *)Tcl_GetChannelInstanceData(chan);

	bits = SSL_CIPHER_get_bits(cipher, &alg_bits);
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("bits", -1));
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewIntObj(bits));
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("secret_bits", -1));
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewIntObj(alg_bits));
	/* alg_bits is actual key secret bits. If use bits and secret (algorithm) bits differ,
           the rest of the bits are fixed, i.e. for limited export ciphers (bits < 56) */
	   the rest of the bits are fixed, i.e. for limited export ciphers (bits < 56) */
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("min_version", -1));
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj(SSL_CIPHER_get_version(cipher), -1));

	/* Get OpenSSL-specific ID, not IANA ID */
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("id", -1));
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewIntObj((int) SSL_CIPHER_get_id(cipher)));

	const unsigned char *session_id;
	char buffer[SSL_MAX_MASTER_KEY_LENGTH];

	/* Report the selected protocol as a result of the ALPN negotiation */
	SSL_SESSION_get0_alpn_selected(session, &proto, &len2);
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("alpn", -1));
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj((char *)proto, (int) len2));

	/* Report the selected protocol as a result of the NPN negotiation */
#ifdef USE_NPN
	SSL_get0_next_proto_negotiated(ssl, &proto, &ulen);
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("npn", -1));
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj((char *)proto, (int) ulen));
#endif

	/* Resumable session */
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("resumable", -1));
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewIntObj(SSL_SESSION_is_resumable(session)));

	/* Session start time (seconds since epoch) */
	Tcl_ListObjAppendElement(interp, objPtr, Tcl_NewStringObj("start_time", -1));

    if (objc < 2) {
	Tcl_WrongNumArgs(interp, 1, objv, "subcommand ?args?");
	return TCL_ERROR;
    }
    if (Tcl_GetIndexFromObj(interp, objv[1], commands, "command", 0,&cmd) != TCL_OK) {
	return TCL_ERROR;
    }

    ERR_clear_error();

    isStr = (cmd == C_STRREQ);
    switch ((enum command) cmd) {
	case C_REQ:
	case C_STRREQ: {
	    EVP_PKEY *pkey=NULL;
	    X509 *cert=NULL;

	Tcl_DecrRefCount(statePtr->callback);
	statePtr->callback = NULL;
    }
    if (statePtr->password) {
	Tcl_DecrRefCount(statePtr->password);
	statePtr->password = NULL;
    }
    if (statePtr->vcmd) {
	Tcl_DecrRefCount(statePtr->vcmd);
	statePtr->vcmd = NULL;
    }

    dprintf("Returning");
}

/*
 *-------------------------------------------------------------------
 *

    static int initialized = 0;
    int status = TCL_OK;
#if defined(OPENSSL_THREADS) && defined(TCL_THREADS)
    size_t num_locks;
#endif

    if (uninitialize) {
        if (!initialized) {
            dprintf("Asked to uninitialize, but we are not initialized");
	if (!initialized) {
	    dprintf("Asked to uninitialize, but we are not initialized");

            return(TCL_OK);
        }
	    return(TCL_OK);
	}

        dprintf("Asked to uninitialize");
	dprintf("Asked to uninitialize");

#if defined(OPENSSL_THREADS) && defined(TCL_THREADS)
        Tcl_MutexLock(&init_mx);
	Tcl_MutexLock(&init_mx);

        if (locks) {
            free(locks);
            locks = NULL;
            locksCount = 0;
        }
	if (locks) {
	    free(locks);
	    locks = NULL;
	    locksCount = 0;
	}
#endif
        initialized = 0;
	initialized = 0;

#if defined(OPENSSL_THREADS) && defined(TCL_THREADS)
        Tcl_MutexUnlock(&init_mx);
	Tcl_MutexUnlock(&init_mx);
#endif

        return(TCL_OK);
	return(TCL_OK);
    }

    if (initialized) {
        dprintf("Called, but using cached value");
        return(status);
	dprintf("Called, but using cached value");
	return(status);
    }

    dprintf("Called");

#if defined(OPENSSL_THREADS) && defined(TCL_THREADS)
    Tcl_MutexLock(&init_mx);
#endif