/*
 * Message Digest (MD) and Message Authentication Code (MAC) Module
 *
 * Provides commands to calculate a message digest (MD) or message
 * authentication code (MAC) using a specified hash function and/or cipher.
 *
 * Copyright (C) 2023 Brian O'Hagan
 *
 */

} DigestState;

/*
 *-------------------------------------------------------------------
 *
 * Tls_DigestNew --
 *
 *	This function creates a per-instance state data structure
 *
 * Returns:
 *	Digest structure pointer
 *
 * Side effects:
 *	Creates structure
 *

}

/*
 *-------------------------------------------------------------------
 *
 * Tls_DigestFree --
 *
 *	This function deletes a digest state structure
 *
 * Returns:
 *	Nothing
 *
 * Side effects:
 *	Removes structure
 *
 *-------------------------------------------------------------------
 */
void Tls_DigestFree(DigestState *statePtr) {
    if (statePtr == (DigestState *) NULL) {
	return;
    }

    /* Remove pending timer */
    if (statePtr->timer != (Tcl_TimerToken) NULL) {
	Tcl_DeleteTimerHandler(statePtr->timer);
    }

    /* Free context structures */
    if (statePtr->ctx != (EVP_MD_CTX *) NULL) {
	EVP_MD_CTX_free(statePtr->ctx);
    }
    if (statePtr->hctx != (HMAC_CTX *) NULL) {
	HMAC_CTX_free(statePtr->hctx);
    }
    if (statePtr->cctx != (CMAC_CTX *) NULL) {

 *	No result or error message
 *
 *-------------------------------------------------------------------
 */
int Tls_DigestInit(Tcl_Interp *interp, DigestState *statePtr, const EVP_MD *md,
	const EVP_CIPHER *cipher, Tcl_Obj *keyObj) {
    int key_len = 0, res = 0;
    const unsigned char *key = NULL;

    /* Create message digest context */
    if (statePtr->format & TYPE_MD) {
	statePtr->ctx = EVP_MD_CTX_new();
	res = (statePtr->ctx != NULL);
    } else if (statePtr->format & TYPE_HMAC) {
	statePtr->hctx = HMAC_CTX_new();
	res = (statePtr->hctx != NULL);
    } else if (statePtr->format & TYPE_CMAC) {
	statePtr->cctx = CMAC_CTX_new();
	res = (statePtr->cctx != NULL);
    }
    if (!res) {
	Tcl_AppendResult(interp, "Create context failed: ", REASON(), NULL);
	return TCL_ERROR;
    }

    /* Get key */
    if (keyObj != NULL) {
	key = Tcl_GetByteArrayFromObj(keyObj, &key_len);
    }

    /* Initialize hash function */
    if (statePtr->format & TYPE_MD) {
	res = EVP_DigestInit_ex(statePtr->ctx, md, NULL);
    } else if (statePtr->format & TYPE_HMAC) {

	res = HMAC_Init_ex(statePtr->hctx, (const void *) key, key_len, md, NULL);
    } else if (statePtr->format & TYPE_CMAC) {

	res = CMAC_Init(statePtr->cctx, (const void *) key, key_len, cipher, NULL);
    }
    if (!res) {
	Tcl_AppendResult(interp, "Initialize failed: ", REASON(), NULL);
	return TCL_ERROR;
    }
    return TCL_OK;
}

/*
 *-------------------------------------------------------------------
 *
 * Tls_DigestUpdate --
 *
 *	Update a hash function with data
 *
 * Returns:
 *	1 if successful or 0 for failure
 *
 * Side effects:
 *	Adds buf data to hash function or sets result to error message
 *
 *-------------------------------------------------------------------
 */
int Tls_DigestUpdate(DigestState *statePtr, char *buf, size_t read, int do_result) {
    int res = 0;

    if (statePtr->format & TYPE_MD) {

}

/*
 *-------------------------------------------------------------------
 *
 * Tls_DigestFinialize --
 *
 *	Finalize a hash function and return the message digest
 *
 * Returns:
 *	TCL_OK if successful or TCL_ERROR for failure with result set
 *	to error message.
 *
 * Side effects:
 *	Sets result to message digest or an error message.
 *
 *-------------------------------------------------------------------
 */
int Tls_DigestFinialize(Tcl_Interp *interp, DigestState *statePtr, Tcl_Obj **resultObj) {
    unsigned char md_buf[EVP_MAX_MD_SIZE];
    unsigned int md_len;
    int res = 0;

    /* Finalize hash function and calculate message digest */
    if (statePtr->format & TYPE_MD) {
	res = EVP_DigestFinal_ex(statePtr->ctx, md_buf, &md_len);
    } else if (statePtr->format & TYPE_HMAC) {
	res = HMAC_Final(statePtr->hctx, md_buf, &md_len);
    } else if (statePtr->format & TYPE_CMAC) {
	size_t len;
	res = CMAC_Final(statePtr->cctx, md_buf, &len);
	md_len = (unsigned int) len;
    }

    if (!res) {
	if (resultObj == NULL) {
	    Tcl_AppendResult(interp, "Finalize failed: ", REASON(), NULL);
	}
	return TCL_ERROR;
    }

    /* Return message digest as either a binary or hex string */
    if (statePtr->format & BIN_FORMAT) {
	if (resultObj == NULL) {
	    Tcl_SetObjResult(interp, Tcl_NewByteArrayObj(md_buf, md_len));
	} else {
	    *resultObj = Tcl_NewByteArrayObj(md_buf, md_len);
	    Tcl_IncrRefCount(*resultObj);
	}

    } else {
	Tcl_Obj *newObj = Tcl_NewObj();
	unsigned char *ptr = Tcl_SetByteArrayLength(newObj, md_len*2);

	for (unsigned int i = 0; i < md_len; i++) {
	    *ptr++ = hex[(md_buf[i] >> 4) & 0x0F];
	    *ptr++ = hex[md_buf[i] & 0x0F];
	}

	if (resultObj == NULL) {
	    Tcl_SetObjResult(interp, newObj);
	} else {
	    *resultObj = newObj;
	    Tcl_IncrRefCount(*resultObj);
	}
    }
    return TCL_OK;
}

/*******************************************************************/

/*

/*
 *-------------------------------------------------------------------
 *
 * DigestCloseProc --
 *
 *	This function is invoked by the generic IO level to perform
 *	channel-type specific cleanup when the channel is closed. All
 *	queued output is flushed prior to calling this function.
 *
 * Returns:
 *	0 if successful or POSIX error code if failed.
 *
 * Side effects:
 *	Deletes stored state data.

 *
 *-------------------------------------------------------------------
 */
int DigestCloseProc(ClientData clientData, Tcl_Interp *interp) {
    DigestState *statePtr = (DigestState *) clientData;

    /* Cancel active timer, if any */
    if (statePtr->timer != (Tcl_TimerToken) NULL) {
	Tcl_DeleteTimerHandler(statePtr->timer);
	statePtr->timer = (Tcl_TimerToken) NULL;
    }

    /* Output message digest if not already done */
    if (!(statePtr->flags & CHAN_EOF)) {
	Tcl_Channel parent = Tcl_GetStackedChannel(statePtr->self);
	Tcl_Obj *resultObj;
	int written;

	if (Digest_Finalize(statePtr->interp, statePtr, &resultObj) == TCL_OK) {
	    unsigned char *data = Tcl_GetByteArrayFromObj(resultObj, &written);
	    Tcl_WriteRaw(parent, data, written);
	    Tcl_DecrRefCount(resultObj);
	}
	statePtr->flags |= CHAN_EOF;
    }

    /* Clean-up */
    Tls_DigestFree(statePtr);
    return 0;
}

/*

/*
 *----------------------------------------------------------------------
 *
 * DigestInputProc --
 *
 *	Called by the generic IO system to read data from transform and
 *	place in buf. Transform gets data from the underlying channel.
 *
 * Returns:
 *	Total bytes read or -1 for an error along with a POSIX error
 *	code in errorCodePtr. Use EAGAIN for nonblocking and no data.
 *
 * Side effects:
 *	Read data from transform and write to buf
 *
 *----------------------------------------------------------------------
 */
int DigestInputProc(ClientData clientData, char *buf, int toRead, int *errorCodePtr) {
    DigestState *statePtr = (DigestState *) clientData;
    Tcl_Channel parent;
    int read;
    *errorCodePtr = 0;

    /* Abort if nothing to process */
    if (toRead <= 0 || statePtr->self == (Tcl_Channel) NULL) {
	return 0;
    }

    /* Get bytes from underlying channel */
    parent = Tcl_GetStackedChannel(statePtr->self);
    read = Tcl_ReadRaw(parent, buf, toRead);

    /* Update hash function */
    if (read > 0) {
	/* Have data */
	if (!Tls_DigestUpdate(statePtr, buf, (size_t) read, 0)) {
	    Tcl_SetChannelError(statePtr->self, Tcl_ObjPrintf("Update failed: %s", REASON()));
	    *errorCodePtr = EINVAL;
	    return 0;
	}
	/* This is correct */
	read = -1;
	*errorCodePtr = EAGAIN;

    } else if (read < 0) {
	/* Error */
	*errorCodePtr = Tcl_GetErrno();

    } else if (!(statePtr->flags & CHAN_EOF)) {
	/* EOF */


	Tcl_Obj *resultObj;


	if (Tls_DigestFinialize(statePtr->interp, statePtr, &resultObj) == TCL_OK) {





	    unsigned char *data = Tcl_GetByteArrayFromObj(resultObj, &read);
	    memcpy(buf, data, read);
	    Tcl_DecrRefCount(resultObj);

	} else {
	    Tcl_SetChannelError(statePtr->self, Tcl_ObjPrintf("Finalize failed: %s", REASON()));
	    *errorCodePtr = EINVAL;















	    read = 0;


	}
	statePtr->flags |= CHAN_EOF;
    }
    return read;
}

/*
 *----------------------------------------------------------------------
 *
 * DigestOutputProc --
 *
 *	Called by the generic IO system to write data in buf to transform.
 *	The transform writes the result to the underlying channel.
 *
 * Returns:
 *	Total bytes written or -1 for an error along with a POSIX error
 *	code in errorCodePtr. Use EAGAIN for nonblocking and can't write data.
 *
 * Side effects:
 *	Get data from buf and update digest

	return 0;
    }

    /* Update hash function */
    if (toWrite > 0 && !Tls_DigestUpdate(statePtr, buf, (size_t) toWrite, 0)) {
	Tcl_SetChannelError(statePtr->self, Tcl_ObjPrintf("Update failed: %s", REASON()));
	*errorCodePtr = EINVAL;
	return 0;
    }
    return toWrite;
}

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

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

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

    /* Create state data structure */
    if ((statePtr = Tls_DigestNew(interp, format)) == NULL) {
	Tcl_AppendResult(interp, "Memory allocation error", (char *) NULL);
	return TCL_ERROR;
    }
    statePtr->self = chan;
    statePtr->mode = mode;

    /* Initialize hash function */
    if (Tls_DigestInit(interp, statePtr, md, cipher, keyObj) != TCL_OK) {
	return TCL_ERROR;
    }

    /* Configure channel */
    Tcl_SetChannelOption(interp, chan, "-translation", "binary");
    if (Tcl_GetChannelBufferSize(chan) < EVP_MAX_MD_SIZE * 2) {
	Tcl_SetChannelBufferSize(chan, EVP_MAX_MD_SIZE * 2);
    }

    /* Stack channel, abort for error */
    statePtr->self = Tcl_StackChannel(interp, &digestChannelType, (ClientData) statePtr, mode, chan);
    if (statePtr->self == (Tcl_Channel) NULL) {
	Tls_DigestFree(statePtr);
	return TCL_ERROR;
    }

    /* Set result to channel Id */

	/* Update hash function */
	if (!Tls_DigestUpdate(statePtr, buf, (size_t) len, 1)) {
	    return TCL_ERROR;
	}

    } else {
	/* Finalize hash function and calculate message digest */
	if (Tls_DigestFinialize(interp, statePtr, NULL) != TCL_OK) {
	    return TCL_ERROR;
	}

	Tcl_DeleteCommandFromToken(interp, statePtr->token);
    }
    return TCL_OK;
}

 *-------------------------------------------------------------------
 */
int Tls_DigestInstance(Tcl_Interp *interp, Tcl_Obj *cmdObj, const EVP_MD *md,
	const EVP_CIPHER *cipher, int format, Tcl_Obj *keyObj) {
    DigestState *statePtr;
    char *cmdName = Tcl_GetStringFromObj(cmdObj, NULL);

    /* Create state data structure */
    if ((statePtr = Tls_DigestNew(interp, format)) == NULL) {
	Tcl_AppendResult(interp, "Memory allocation error", (char *) NULL);
	return TCL_ERROR;
    }

    /* Initialize hash function */
    if (Tls_DigestInit(interp, statePtr, md, cipher, keyObj) != TCL_OK) {

    /* Get data */
    data = Tcl_GetByteArrayFromObj(dataObj, &data_len);
    if (data == NULL || data_len == 0) {
	Tcl_SetResult(interp, "No data", NULL);
	return TCL_ERROR;
    }

    /* Create state data structure */
    if ((statePtr = Tls_DigestNew(interp, format)) == NULL) {
	Tcl_AppendResult(interp, "Memory allocation error", (char *) NULL);
	return TCL_ERROR;
    }

    /* Calc Digest, abort for error */
    if (Tls_DigestInit(interp, statePtr, md, cipher, keyObj) != TCL_OK ||
	Tls_DigestUpdate(statePtr, data, (size_t) data_len, 1) == 0 ||
	Tls_DigestFinialize(interp, statePtr, NULL) != TCL_OK) {
	Tls_DigestFree(statePtr);
	return TCL_ERROR;
    }

    /* Clean-up */
    Tls_DigestFree(statePtr);
    return TCL_OK;
}

/*******************************************************************/

/*

int Tls_DigestFile(Tcl_Interp *interp, Tcl_Obj *filename, const EVP_MD *md,
	const EVP_CIPHER *cipher, int format, Tcl_Obj *keyObj) {
    DigestState *statePtr;
    Tcl_Channel chan = NULL;
    unsigned char buf[BUFFER_SIZE];
    int res = TCL_OK, len;

    /* Create state data structure */
    if ((statePtr = Tls_DigestNew(interp, format)) == NULL) {
	Tcl_AppendResult(interp, "Memory allocation error", (char *) NULL);
	return TCL_ERROR;
    }

    /* Open file channel, abort for error */
    chan = Tcl_FSOpenFileChannel(interp, filename, "rb", 0444);
    if (chan == (Tcl_Channel) NULL) {
	Tls_DigestFree(statePtr);
	return TCL_ERROR;
    }

    /* Configure channel */

		res = TCL_ERROR;
		goto done;
	    }
	}
    }

    /* Finalize hash function and calculate message digest */
    res = Tls_DigestFinialize(interp, statePtr, NULL);

done:
    /* Close channel */
    if (Tcl_Close(interp, chan) == TCL_ERROR) {
	res = TCL_ERROR;
    }

 *
 * Side effects:
 *	Sets result to message digest or error message
 *
 *-------------------------------------------------------------------
 */
static int DigestMain(int type, Tcl_Interp *interp, int objc, Tcl_Obj *const objv[]) {
    int idx, format = HEX_FORMAT, res = TCL_OK, flags = 0;
    const char *digestName, *channel = NULL;
    Tcl_Obj *cmdObj = NULL, *dataObj = NULL, *fileObj = NULL, *keyObj = NULL;
    unsigned char *cipherName = NULL;
    const EVP_MD *md = NULL;
    const EVP_CIPHER *cipher = NULL;

    /* Clear interp result */

	} else {
	    Tcl_AppendResult(interp, "Invalid digest \"", digestName, "\"", NULL);
	    return TCL_ERROR;
	}
    }

    /* Get options */
    for (idx = 1; idx < objc; idx++) {
	char *opt = Tcl_GetStringFromObj(objv[idx], NULL);

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

	OPTFLAG("-bin", format, BIN_FORMAT);

	OPTOBJ("-filename", fileObj);
	OPTOBJ("-key", keyObj);

	OPTBAD("option", "-bin, -channel, -cipher, -command, -data, -digest, -file, -filename, -hex, or -key");
	return TCL_ERROR;
    }






    /* Get cipher */
    if (cipherName != NULL) {
	cipher = EVP_get_cipherbyname(cipherName);
	type = TYPE_CMAC;
	if (cipher == NULL) {
	    Tcl_AppendResult(interp, "Invalid cipher \"", cipherName, "\"", NULL);
	    return TCL_ERROR;

 *	TCL_OK or TCL_ERROR
 *
 * Side effects:
 *	Sets result to message digest or error message
 *
 *-------------------------------------------------------------------
 */
 #define validate_argc(objc, objv) { \
    if (objc != 2) { \
	Tcl_WrongNumArgs(interp, 1, objv, "data"); \
	return TCL_ERROR; \
    } \
}
 
int DigestMD4Cmd(ClientData clientData, Tcl_Interp *interp, int objc, Tcl_Obj *const objv[]) {
    validate_argc(objc, objv);
    return Tls_DigestData(interp, objv[1], EVP_md4(), NULL, HEX_FORMAT | TYPE_MD, NULL);
}

int DigestMD5Cmd(ClientData clientData, Tcl_Interp *interp, int objc, Tcl_Obj *const objv[]) {
    validate_argc(objc, objv);



    return Tls_DigestData(interp, objv[1], EVP_md5(), NULL, HEX_FORMAT | TYPE_MD, NULL);
}

int DigestSHA1Cmd(ClientData clientData, Tcl_Interp *interp, int objc, Tcl_Obj *const objv[]) {
    validate_argc(objc, objv);



    return Tls_DigestData(interp, objv[1], EVP_sha1(), NULL, HEX_FORMAT | TYPE_MD, NULL);
}

int DigestSHA256Cmd(ClientData clientData, Tcl_Interp *interp, int objc, Tcl_Obj *const objv[]) {
    validate_argc(objc, objv);



    return Tls_DigestData(interp, objv[1], EVP_sha256(), NULL, HEX_FORMAT | TYPE_MD, NULL);
}

int DigestSHA512Cmd(ClientData clientData, Tcl_Interp *interp, int objc, Tcl_Obj *const objv[]) {
    validate_argc(objc, objv);



    return Tls_DigestData(interp, objv[1], EVP_sha512(), NULL, HEX_FORMAT | TYPE_MD, NULL);
}

/*
 *-------------------------------------------------------------------
 *
 * Tls_DigestCommands --