*	1 = Command returned success or eval returned TCL_OK
 *
 * Side effects:
 *	Evaluates callback command
 *
 *-------------------------------------------------------------------
 */
 
static int
EvalCallback(
    Tcl_Interp *interp,		/* Tcl interpreter */
    State *statePtr,		/* Client state for TLS socket */
    Tcl_Obj *cmdPtr)		/* Command to eval as a Tcl object */
{
    int code, ok = 0;

 *	None
 *
 * Side effects:
 *	Calls callback (if defined)
 *
 *-------------------------------------------------------------------
 */
 
static void
InfoCallback(
    const SSL *ssl,		/* SSL context */
    int where,			/* Source of info */
    int ret)			/* message enum */
{
    State *statePtr = (State*)SSL_get_app_data((SSL *)ssl);

 *	None
 *
 * Side effects:
 *	Calls callback (if defined)
 *
 *-------------------------------------------------------------------
 */
 
#ifndef OPENSSL_NO_SSL_TRACE
static void
MessageCallback(
    int write_p,		/* Message 0=received, 1=sent */
    int version,		/* TLS version */
    int content_type,		/* Protocol content type */
    const void *buf,		/* Protocol message */

 *
 * 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,			/* Verify result */
    X509_STORE_CTX *ctx)	/* CTX context */
{
    Tcl_Obj *cmdPtr;
    SSL   *ssl		= (SSL*)X509_STORE_CTX_get_ex_data(ctx, SSL_get_ex_data_X509_STORE_CTX_idx());

 *
 * 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,		/* Client state for TLS socket */
    const char *msg)		/* Error message */
{
    Tcl_Interp *interp	= statePtr->interp;
    Tcl_Obj *cmdPtr, *listPtr;

 *	Write received key data to log file.
 *
 * Side effects:
 *	none
 *
 *-------------------------------------------------------------------
 */
 
void KeyLogCallback(
    const SSL *ssl,		/* Client state for TLS socket */
    const char *line)		/* Key data to be logged */
{
    char *str = getenv(SSLKEYLOGFILE);
    FILE *fd;

 *	Calls callback (if defined)
 *
 * Returns:
 *	Password size in bytes or -1 for an error.
 *
 *-------------------------------------------------------------------
 */
 
static int
PasswordCallback(
    char *buf,			/* Pointer to buffer to store password in */
    int size,			/* Buffer length in bytes */
    int rwflag,			/* Whether password is needed for read or write */
    void *udata)		/* Client state for TLS socket */
{

 *
 * Return codes:
 *	0 = error where session will be immediately removed from the internal cache.
 *	1 = success where app retains session in session cache, and must call SSL_SESSION_free() when done.
 *
 *-------------------------------------------------------------------
 */
 
static int
SessionCallback(
    SSL *ssl,			/* SSL context */
    SSL_SESSION *session)	/* Session context */
{
    State *statePtr = (State*)SSL_get_app_data((SSL *)ssl);
    Tcl_Interp *interp	= statePtr->interp;

 *	SSL_TLSEXT_ERR_ALERT_FATAL: There was no overlap between the client's
 *	    supplied list and the server configuration. The connection will be aborted.
 *	SSL_TLSEXT_ERR_NOACK: ALPN protocol not selected, e.g., because no ALPN
 *	    protocols are configured for this connection. The connection continues.
 *
 *-------------------------------------------------------------------
 */
 
static int
ALPNCallback(
    SSL *ssl,			/* SSL context */
    const unsigned char **out,	/* Return buffer to store selected protocol */
    unsigned char *outlen,	/* Return buffer size */
    const unsigned char *in,	/* Peer provided protocols */
    unsigned int inlen,		/* Peer buffer size */

 *
 * 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,		/* SSL context */
    const unsigned char **out,	/* Return buffer to store selected protocol */
    unsigned int *outlen,	/* Return buffer size */
    void *arg)			/* Client state for TLS socket */

 *	SSL_TLSEXT_ERR_ALERT_WARNING: SNI hostname is not accepted, warning alert
 *	    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,		/* SSL context */
    int *alert,			/* Returned alert message */
    void *arg)			/* Client state for TLS socket */
{
    State *statePtr = (State*)arg;

 * 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
 *
 *-------------------------------------------------------------------
 */
 
static int
HelloCallback(
    SSL *ssl,			/* SSL context */
    int *alert,			/* Returned alert message */
    void *arg)			/* Client state for TLS socket */
{
    State *statePtr = (State*)arg;

 *	A standard Tcl result list.
 *
 * Side effects:
 *	constructs and destroys SSL context (CTX)
 *
 *-------------------------------------------------------------------
 */
 
static const char *protocols[] = {
    "ssl2", "ssl3", "tls1", "tls1.1", "tls1.2", "tls1.3", NULL
};
enum protocol {
    TLS_SSL2, TLS_SSL3, TLS_TLS1, TLS_TLS1_1, TLS_TLS1_2, TLS_TLS1_3, TLS_NONE
};

    }
    statePtr = (State *)Tcl_GetChannelInstanceData(chan);

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

    if (ret < 0 && ((statePtr->flags & TLS_TCL_ASYNC) && (err == EAGAIN))) {
    if (ret <= 0 && ((statePtr->flags & TLS_TCL_ASYNC) && (err == EAGAIN))) {
	dprintf("Async set and err = EAGAIN");
	ret = 0;
    } else if (ret < 0) {
	long result;
	errStr = statePtr->err;
	Tcl_ResetResult(interp);
	Tcl_SetErrno(err);

 *	Number of certificates loaded or 0 for none.
 *
 * Side effects:
 *	Loads CA certificates
 *
 *-------------------------------------------------------------------
 */
 
static int
TlsLoadClientCAFileFromMemory(
    Tcl_Interp *interp,		/* Tcl interpreter */
    SSL_CTX *ctx,		/* CTX context */
    Tcl_Obj *file)		/* CA certificates filename */
{
    BIO  *bio  = NULL;

 *	A standard Tcl result.
 *
 * Side effects:
 *	None.
 *
 *-------------------------------------------------------------------
 */
 
static int
StatusObjCmd(
    TCL_UNUSED(ClientData),	/* Client data */
    Tcl_Interp *interp,		/* Tcl interpreter */
    int objc,			/* Arg count */
    Tcl_Obj *const objv[])	/* Arguments as Tcl objects */
{

 *	A standard Tcl result.
 *
 * Side effects:
 *	None.
 *
 *-------------------------------------------------------------------
 */
 
static int
VersionObjCmd(
    TCL_UNUSED(ClientData),	/* Client data */
    Tcl_Interp *interp,		/* Tcl interpreter */
    TCL_UNUSED(int),		/* objc - Arg count */
    TCL_UNUSED(Tcl_Obj *const *)) /* objv - Arguments as Tcl objects */
{

 *	A standard Tcl result.
 *
 * Side effects:
 *	None.
 *
 *-------------------------------------------------------------------
 */
 
static int
MiscObjCmd(
    TCL_UNUSED(ClientData),	/* Client data */
    Tcl_Interp *interp,		/* Tcl interpreter */
    int objc,			/* Arg count */
    Tcl_Obj *const objv[])	/* Arguments as Tcl objects */
{

 *	none
 *
 * Side effects:
 *	Frees all the state
 *
 *-------------------------------------------------------------------
 */
 
void
Tls_Free(
    tls_free_type *blockPtr)	/* Client state for TLS socket */
{
    State *statePtr = (State *)blockPtr;

    dprintf("Called");

 *	none
 *
 * Side effects:
 *	Frees all the state
 *
 *-------------------------------------------------------------------
 */
 
void Tls_Clean(
    State *statePtr)		/* Client state for TLS socket */
{
    dprintf("Called");

    /*
     * we're assuming here that we're single-threaded

 *	A standard TCL result
 *
 * Side effects:
 *	Shutdown SSL library
 *
 *------------------------------------------------------*
 */
 
void TlsLibShutdown(
    ClientData clientData)	/* Not used */
{
    dprintf("Called");

    BIO_cleanup();
}

 *	A standard Tcl result
 *
 * Side effects:
 *	Initializes SSL library
 *
 *------------------------------------------------------*
 */
 
static int TlsLibInit() {
    static int initialized = 0;

    dprintf("Called");

    if (!initialized) {
	/* Initialize BOTH libcrypto and libssl. */

 *	Same as of 'Tls_Init'
 *
 * Side effects:
 *	Same as of 'Tls_Init'
 *
 *-------------------------------------------------------------------
 */
 
DLLEXPORT int Tls_SafeInit(
    Tcl_Interp *interp)		/* Tcl interpreter */
{
    dprintf("Called");
    return Tls_Init(interp);
}