*	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))) {
	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);
}

/*
 * Provides Custom BIO layer to interface OpenSSL with TCL. These functions
 * directly interface between the TCL IO channel and BIO buffers.
 *
 * Copyright (C) 1997-2000 Matt Newman <[email protected]>
 * Copyright (C) 2024 Brian O'Hagan
 *
 */

/*
				Normal
		tlsBIO.c				tlsIO.c
 +------+                        +---+                                 +---+
 |      |Tcl_WriteRaw<--BioOutput|SSL|BIO_write<--TlsOutputProc<--Write|   |
 |socket|      <encrypted>       |BIO|            <unencrypted>        |App|
 |      |Tcl_ReadRaw --> BioInput|   |BIO_Read -->TlsInputProc --> Read|   |
 +------+                        +---+                                 +---+


				Fast Path
					tlsIO.c
  +------+             +-----+                                     +-----+
  |      |<-- write <--| SSL |BIO_write <-- TlsOutputProc <-- Write|     |
  |socket| <encrypted> | BIO |            <unencrypted>            | App |
  |      |<--  read <--|     |BIO_Read  --> TlsInputProc  -->  Read|     |
  +------+             +-----+                                     +-----+
*/

#include "tlsInt.h"
#include <openssl/bio.h>

/* Define BIO methods structure */
static BIO_METHOD *BioMethods = NULL;

 * Also work done by the follow people provided the impetus to do this "right":
 *	tclSSL (Colin McCormack, Shared Technology)
 *	SSLtcl (Peter Antman)
 *
 */

/*
				Normal
		tlsBIO.c				tlsIO.c
 +------+                        +---+                                 +---+
 |      |Tcl_WriteRaw<--BioOutput|SSL|BIO_write<--TlsOutputProc<--Write|   |
 |socket|      <encrypted>       |BIO|            <unencrypted>        |App|
 |      |Tcl_ReadRaw --> BioInput|   |BIO_Read -->TlsInputProc --> Read|   |
 +------+                        +---+                                 +---+


				Fast Path
					tlsIO.c
  +------+             +-----+                                     +-----+
  |      |<-- write <--| SSL |BIO_write <-- TlsOutputProc <-- Write|     |
  |socket| <encrypted> | BIO |            <unencrypted>            | App |
  |      |<--  read <--|     |BIO_Read  --> TlsInputProc  -->  Read|     |
  +------+             +-----+                                     +-----+
*/

#include "tlsInt.h"
#include <errno.h>

/*
 *-----------------------------------------------------------------------------

		bioShouldRetry = 1;
	    } else if (rc == SSL_ERROR_WANT_READ) {
		bioShouldRetry = 1;
		statePtr->want |= TCL_READABLE;
	    } else if (rc == SSL_ERROR_WANT_WRITE) {
		bioShouldRetry = 1;
		statePtr->want |= TCL_WRITABLE;




	    }
	}

	if (bioShouldRetry) {
	    dprintf("The I/O did not complete -- but we should try it again");

	    if (statePtr->flags & TLS_TCL_ASYNC) {

	dprintf("We have either completely established the session or completely failed it -- there is no more need to ever retry it though");
	break;
    }

    switch (rc) {
	case SSL_ERROR_NONE:
	    /* The TLS/SSL I/O operation completed successfully */
	    dprintf("SSL_ERROR_NONE");
	    *errorCodePtr = 0;
	    break;

	case SSL_ERROR_SSL:
	    /* A non-recoverable, fatal error in the SSL library occurred,
	       usually a protocol error. This includes certificate validation
	       errors. */
	    dprintf("SSL_ERROR_SSL: Fatal SSL protocol error occurred");
	    if (SSL_get_verify_result(statePtr->ssl) != X509_V_OK) {
		Tls_Error(statePtr,
		    X509_verify_cert_error_string(SSL_get_verify_result(statePtr->ssl)));
	    }
	    if (backingError != 0) {
		Tls_Error(statePtr, ERR_reason_error_string(backingError));
	    }
	    statePtr->flags |= TLS_TCL_HANDSHAKE_FAILED;
	    *errorCodePtr = ECONNABORTED;
	    return -1;

	case SSL_ERROR_WANT_READ:
	    /* More data must be read from the underlying BIO layer in order to
	       complete the actual SSL_*() operation.  */
	    dprintf("SSL_ERROR_WANT_READ");
	    BIO_set_retry_read(statePtr->bio);
	    *errorCodePtr = EAGAIN;
	    dprintf("ERR(SSL_ERROR_WANT_READ, EAGAIN)");
	    statePtr->want |= TCL_READABLE;
	    return 0;

	case SSL_ERROR_WANT_WRITE:
	    /* There is data in the SSL buffer that must be written to the
	       underlying BIO in order to complete the SSL_*() operation. */
	    dprintf("SSL_ERROR_WANT_WRITE");
	    BIO_set_retry_write(statePtr->bio);
	    *errorCodePtr = EAGAIN;
	    dprintf("ERR(SSL_ERROR_WANT_WRITE, EAGAIN)");
	    statePtr->want |= TCL_WRITABLE;
	    return 0;

	case SSL_ERROR_WANT_X509_LOOKUP:
	    /* The operation did not complete because an application callback
	       set by SSL_CTX_set_client_cert_cb() has asked to be called again. */
	    dprintf("SSL_ERROR_WANT_X509_LOOKUP");
	    BIO_set_retry_special(statePtr->bio);
	    BIO_set_retry_reason(statePtr->bio, BIO_RR_SSL_X509_LOOKUP);
	    *errorCodePtr = EAGAIN;
	    dprintf("ERR(SSL_ERROR_WANT_X509_LOOKUP, EAGAIN)");
	    return 0;

	case SSL_ERROR_SYSCALL:
	    /* Some non-recoverable, fatal I/O error occurred */
	    dprintf("SSL_ERROR_SYSCALL: Fatal I/O error occurred");

	    if (backingError == 0 && err == 0) {
		dprintf("EOF reached")
		*errorCodePtr = ECONNRESET;
		Tls_Error(statePtr, "(unexpected) EOF reached");

	    } else if (backingError == 0 && err == -1) {

		Tls_Error(statePtr, ERR_reason_error_string(backingError));
	    }

	    statePtr->flags |= TLS_TCL_HANDSHAKE_FAILED;
	    return -1;

	case SSL_ERROR_ZERO_RETURN:
	    /* Peer has cleanly closed the connection by sending the close_notify
	       alert. Can't read, but can write. Need to return an EOF, so the
	       channel is closed which will send an SSL_shutdown(). */
	    dprintf("SSL_ERROR_ZERO_RETURN: Peer has closed the connection");
	    *errorCodePtr = ECONNRESET;
	    Tls_Error(statePtr, "Peer has closed the connection for writing by sending the close_notify alert");
	    return -1;

	case SSL_ERROR_WANT_CONNECT:








	    /* The operation did not complete and connect would have blocked.









	       Retry again after connection is established. */


	    dprintf("SSL_ERROR_WANT_CONNECT");
	    BIO_set_retry_special(statePtr->bio);
	    BIO_set_retry_reason(statePtr->bio, BIO_RR_CONNECT);
	    *errorCodePtr = EAGAIN;
	    dprintf("ERR(SSL_ERROR_WANT_CONNECT, EAGAIN)");
	    return 0;

	case SSL_ERROR_WANT_ACCEPT:
	    /* The operation did not complete and accept would have blocked.
	       Retry again after connection is established. */
	    dprintf("SSL_ERROR_WANT_ACCEPT");
	    BIO_set_retry_special(statePtr->bio);
	    BIO_set_retry_reason(statePtr->bio, BIO_RR_ACCEPT);
	    *errorCodePtr = EAGAIN;
	    dprintf("ERR(SSL_ERROR_WANT_ACCEPT, EAGAIN)");












	    return 0;

	case SSL_ERROR_WANT_ASYNC:
	    /* Used with flag SSL_MODE_ASYNC, op didn't complete because an
	       async engine is still processing data */
	case SSL_ERROR_WANT_ASYNC_JOB:
	    /* The asynchronous job could not be started because there were no
	       async jobs available in the pool. */
	case SSL_ERROR_WANT_CLIENT_HELLO_CB:
	    /* The operation did not complete because an application callback
	       set by SSL_CTX_set_client_hello_cb() has asked to be called again. */
#if OPENSSL_VERSION_NUMBER >= 0x30000000L
	case SSL_ERROR_WANT_RETRY_VERIFY:
	    /* The operation did not complete because a certificate verification
	       callback has asked to be called again via SSL_set_retry_verify(3). */
#endif
	default:
	    /* The operation did not complete and should be retried later. */
	    dprintf("Operation did not complete, call function again later");
	    *errorCodePtr = EAGAIN;
	    dprintf("ERR(Other, EAGAIN)");
	    return 0;
    }

    dprintf("Removing the \"TLS_TCL_INIT\" flag since we have completed the handshake");
    statePtr->flags &= ~TLS_TCL_INIT;

    dprintf("Returning success");

    if (statePtr->flags & TLS_TCL_INIT) {
	int tlsConnect;

	dprintf("Calling Tls_WaitForConnect");

	tlsConnect = Tls_WaitForConnect(statePtr, errorCodePtr, 0);
	if (tlsConnect < 0) {
	    /* Failure, so abort */
	    dprintf("Got an error waiting to connect (tlsConnect = %i, *errorCodePtr = %i)", tlsConnect, *errorCodePtr);

	    bytesRead = -1;
	    if (*errorCodePtr == ECONNRESET) {
		dprintf("Got connection reset");
		/* Soft EOF */
		*errorCodePtr = 0;
		bytesRead = 0;
	    }
	    return bytesRead;
	} else if (tlsConnect == 0) {
	    /* Try again */
	    bytesRead = -1;
	    return bytesRead;
	}
    }

    /*
     * We need to clear the SSL error stack now because we sometimes reach
     * this function with leftover errors in the stack.  If BIO_read

	    dprintf("BIO has pending data to write");
	    statePtr->want |= TCL_WRITABLE;
	}
	if (BIO_should_io_special(statePtr->bio)) {
	    int reason = BIO_get_retry_reason(statePtr->bio);
	    dprintf("BIO has some special condition other than read or write: code=%d", reason);
	}

    }

    switch (err) {
	case SSL_ERROR_NONE:
	    /* I/O operation completed */
	    dprintf("SSL_ERROR_NONE");
	    dprintBuffer(buf, bytesRead);
	    break;

	case SSL_ERROR_SSL:
	    /* A non-recoverable, fatal error in the SSL library occurred,
	       usually a protocol error. */
	    dprintf("SSL_ERROR_SSL: Fatal SSL protocol error occurred");
	    if (backingError != 0) {
		Tls_Error(statePtr, ERR_reason_error_string(backingError));
	    } else if (SSL_get_verify_result(statePtr->ssl) != X509_V_OK) {
		Tls_Error(statePtr,
		    X509_verify_cert_error_string(SSL_get_verify_result(statePtr->ssl)));
	    } else {
		Tls_Error(statePtr, "Unknown SSL error");

	    *errorCodePtr = EAGAIN;
	    bytesRead = -1;
	    statePtr->want |= TCL_WRITABLE;
	    BIO_set_retry_write(statePtr->bio);
	    break;

	case SSL_ERROR_WANT_X509_LOOKUP:
	    /* The operation did not complete because an application callback
	       set by SSL_CTX_set_client_cert_cb() has asked to be called again. */
	    dprintf("Got SSL_ERROR_WANT_X509_LOOKUP, mapping it to EAGAIN");
	    *errorCodePtr = EAGAIN;
	    bytesRead = -1;
	    break;

	case SSL_ERROR_SYSCALL:
	    /* Some non-recoverable, fatal I/O error occurred */
	    dprintf("SSL_ERROR_SYSCALL: Fatal I/O error occurred");

	    if (backingError == 0 && bytesRead == 0) {
		/* Unexpected EOF from the peer for OpenSSL 1.1 */
		dprintf("(Unexpected) EOF reached")
		*errorCodePtr = 0;
		bytesRead = 0;
		Tls_Error(statePtr, "EOF reached");

		*errorCodePtr = Tcl_GetErrno();
		bytesRead = -1;
		Tls_Error(statePtr, ERR_reason_error_string(backingError));
	    }
	    break;

	case SSL_ERROR_ZERO_RETURN:
	    /* Peer has cleanly closed the connection by sending the close_notify
	       alert. Can't read, but can write. Need to return an EOF, so the
	       channel is closed which will send an SSL_shutdown(). */
	    dprintf("SSL_ERROR_ZERO_RETURN: Peer has closed the connection");
	    bytesRead = 0;
	    *errorCodePtr = 0;
	    Tls_Error(statePtr, "Peer has closed the connection for writing by sending the close_notify alert");
	    break;

	case SSL_ERROR_WANT_ASYNC:
	    /* Used with flag SSL_MODE_ASYNC, operation didn't complete because
	       an async engine is still processing data. */
	    dprintf("Got SSL_ERROR_WANT_ASYNC, mapping this to EAGAIN");
	    *errorCodePtr = EAGAIN;
	    bytesRead = 0;
	    break;

	default:
	    dprintf("Unknown error (err = %i), mapping to EOF", err);
	    *errorCodePtr = 0;
	    bytesRead = 0;
	    Tls_Error(statePtr, "Unknown error");

	    if (*errorCodePtr == ECONNRESET) {
		dprintf("Got connection reset");
		/* Soft EOF */
		*errorCodePtr = 0;
		written = 0;
	    }
	    return written;
	} else if (tlsConnect == 0) {
	    /* Try again */
	    written = -1;
	    return written;
	}
    }

    if (toWrite == 0) {
	dprintf("zero-write");
	err = BIO_flush(statePtr->bio);

	if (BIO_should_write(statePtr->bio)) {
	    dprintf("BIO has pending data to write");
	}
	if (BIO_should_io_special(statePtr->bio)) {
	    int reason = BIO_get_retry_reason(statePtr->bio);
	    dprintf("BIO has some special condition other than read or write: code=%d", reason);
	}


    } else {
	BIO_flush(statePtr->bio);
    }

    switch (err) {
	case SSL_ERROR_NONE:
	    /* I/O operation completed */
	    dprintf("SSL_ERROR_NONE");
	    if (written < 0) {
		written = 0;
	    }
	    break;

	case SSL_ERROR_SSL:
	    /* A non-recoverable, fatal error in the SSL library occurred,
	       usually a protocol error */
	    dprintf("SSL_ERROR_SSL: Fatal SSL protocol error occurred");
	    if (backingError != 0) {
		Tls_Error(statePtr, ERR_reason_error_string(backingError));
	    } else if (SSL_get_verify_result(statePtr->ssl) != X509_V_OK) {
		Tls_Error(statePtr,
		    X509_verify_cert_error_string(SSL_get_verify_result(statePtr->ssl)));
	    } else {
		Tls_Error(statePtr, "Unknown SSL error");
	    }
	    *errorCodePtr = ECONNABORTED;
	    written = -1;
	    break;

	case SSL_ERROR_WANT_READ:
	    /* Operation did not complete due to not enough data was available.
	       Retry again later with same data. */
	    dprintf("Got SSL_ERROR_WANT_READ, mapping it to EAGAIN");
	    *errorCodePtr = EAGAIN;
	    written = -1;
	    statePtr->want |= TCL_READABLE;
	    BIO_set_retry_read(statePtr->bio);
	    break;

	case SSL_ERROR_WANT_WRITE:
	    /* Operation did not complete due to unable to send all data to the
	       BIO. Retry later with same data. */
	    dprintf("Got SSL_ERROR_WANT_WRITE, mapping it to EAGAIN");
	    *errorCodePtr = EAGAIN;
	    written = -1;
	    statePtr->want |= TCL_WRITABLE;
	    BIO_set_retry_write(statePtr->bio);
	    break;

	case SSL_ERROR_WANT_X509_LOOKUP:
	    /* The operation did not complete because an application callback
	       set by SSL_CTX_set_client_cert_cb() has asked to be called again. */
	    dprintf("Got SSL_ERROR_WANT_X509_LOOKUP, mapping it to EAGAIN");
	    *errorCodePtr = EAGAIN;
	    written = -1;
	    break;

	case SSL_ERROR_SYSCALL:
	    /* Some non-recoverable, fatal I/O error occurred */
	    dprintf("SSL_ERROR_SYSCALL: Fatal I/O error occurred");

	    if (backingError == 0 && written == 0) {
		dprintf("EOF reached")
		*errorCodePtr = 0;
		written = 0;
		Tls_Error(statePtr, "EOF reached");

		*errorCodePtr = Tcl_GetErrno();
		written = -1;
		Tls_Error(statePtr, ERR_reason_error_string(backingError));
	    }
	    break;

	case SSL_ERROR_ZERO_RETURN:
	    /* Peer has cleanly closed the connection by sending the close_notify
	       alert. Can't read, but can write. Need to return an EOF, so the
	       channel is closed which will send an SSL_shutdown(). */
	    dprintf("SSL_ERROR_ZERO_RETURN: Peer has closed the connection");
	    *errorCodePtr = 0;
	    written = 0;
	    Tls_Error(statePtr, "Peer has closed the connection for writing by sending the close_notify alert");
	    break;

	case SSL_ERROR_WANT_ASYNC:
	    /* Used with flag SSL_MODE_ASYNC, operation didn't complete because
	       an async engine is still processing data. */
	    dprintf("Got SSL_ERROR_WANT_ASYNC, mapping this to EAGAIN");
	    *errorCodePtr = EAGAIN;
	    written = 0;
	    break;

	default:
	    dprintf("unknown error: %d", err);
	    Tls_Error(statePtr, "Unknown error");
	    break;
    }

 */
static void
TlsWatchProc(
    ClientData instanceData,	/* Connection state info */
    int mask)			/* Events of interest; an OR-ed combination of
				 * TCL_READABLE, TCL_WRITABLE and TCL_EXCEPTION. */
{
    Tcl_Channel parent;
    State *statePtr = (State *) instanceData;
    Tcl_DriverWatchProc *watchProc;
    int pending = 0;

    dprintf("Called with mask 0x%02x", mask);
    dprintFlags(statePtr);

	watchProc(Tcl_GetChannelInstanceData(parent), 0);
	statePtr->watchMask = 0;
	return;
    }

    statePtr->watchMask = mask;

    /*
     * No channel handlers any more. We will be notified automatically about
     * events on the channel below via a call to our 'TransformNotifyProc'. But
     * we have to pass the interest down now. We are allowed to add additional
     * 'interest' to the mask if we want to, but this transformation has no
     * such interest. It just passes the request down, unchanged.
     */
    dprintf("Registering our interest in the lower channel (chan=%p)", (void *) parent);
    watchProc = Tcl_ChannelWatchProc(Tcl_GetChannelType(parent));
    watchProc(Tcl_GetChannelInstanceData(parent), mask);

    /* Do we have any pending data */
    pending = (statePtr->want || \
	((mask & TCL_READABLE) && ((Tcl_InputBuffered(statePtr->self) > 0) || (BIO_ctrl_pending(statePtr->bio) > 0))) ||
	((mask & TCL_WRITABLE) && ((Tcl_OutputBuffered(statePtr->self) > 0) || (BIO_ctrl_wpending(statePtr->bio) > 0))));

    dprintf("IO Want=%d, input buffer=%d, output buffer=%d, BIO pending=%zd, BIO wpending=%zd, pending=%d", \
	statePtr->want, Tcl_InputBuffered(statePtr->self), Tcl_OutputBuffered(statePtr->self), \
	BIO_ctrl_pending(statePtr->bio), BIO_ctrl_wpending(statePtr->bio), pending);

    /* Schedule next event if data is pending, otherwise cease events for now */
    if (!(mask & TCL_READABLE) || pending == 0) {
	/* Remove timer, if any */
	if (statePtr->timer != (Tcl_TimerToken) NULL) {
	    dprintf("A timer was found, deleting it");
	    Tcl_DeleteTimerHandler(statePtr->timer);
	    statePtr->timer = (Tcl_TimerToken) NULL;
	}

	}
    }

    /*
     * Delete an existing timer. It was not fired, yet we are here, so the
     * channel below generated such an event and we don't have to. The renewal
     * of the interest after the execution of channel handlers will eventually
     * cause us to recreate the timer (in TlsWatchProc).
     */
    if (statePtr->timer != (Tcl_TimerToken) NULL) {
	Tcl_DeleteTimerHandler(statePtr->timer);
	statePtr->timer = (Tcl_TimerToken) NULL;
    }

    /*