# nu (ν)

# Running

## Configuration

The application can be configured using a `.env` file. Here are the available options:

`RESPONSE_TIMEOUT`

- Specifies the response timeout in seconds.

- Default: `5`

- Example: `RESPONSE_TIMEOUT=5`

`CLIENT_IDLE_TIMEOUT`

- Defines the client idle timeout in seconds.

- Default: `60`

- Example: `CLIENT_IDLE_TIMEOUT=60`

`VERBOSITY`

- Determines the logging verbosity level.

- Valid values: DEBUG, INFO, WARNING, ERROR, CRITICAL.

- Default: `INFO`

- Example: `VERBOSITY=DEBUG`

`SCAN_PORT_RANGE`

- Defines the port range to scan as `PORT:PORT` separated by colon (`:`).

- The ports must be valid and there must be exactly two of them.

- Example: `SCAN_PORT_RANGE=65525:65535`

`IP`

- Manually set the IP address.

- Example: `IP=127.0.0.1`

## Running

The application requires a few dependenices, specified in `requirements.txt`.

To install these dependencies run

```bash
pip install -r requirements.txt
```

Upon successful installation, the program is ready to run. The database used is SQLite, hence no SQL structure is needed to be imported, nor are any credentials required.

To run the app, run

```bash
python src/app.py
```

If the verbosity set in `.env` is `DEBUG`, the program will print many useful descriptions of it's actions together with a detailed location of the action including file, line and process name.

## Definitions

The program uses the following protocol over TCP

| Operation              | Request Format                   | Response Format |
| ---------------------- | -------------------------------- | --------------- |
| Bank code              | BC                               | BC \<ip\>       |
| Account create         | AC \<account\>/\<ip\>            | AC              |
| Account deposit        | AD \<account\>/\<ip\> \<number\> | AD              |
| Account withdrawal     | AW \<account\>/\<ip\> \<number\> | AW              |
| Account balance        | AB \<account\>/\<ip\>            | AB \<number\>   |
| Account remove         | AR \<account\>/\<ip\>            | AR              |
| Bank (total) amount    | BA                               | BA \<number\>   |
| Bank number of clients | BN                               | BN \<number\>   |

Any of these commands may return an error message in format

`ER <message>`

## Sources

### Signal catching

- [Catch SIGTERM](https://dnmtechs.com/graceful-sigterm-signal-handling-in-python-3-best-practices-and-implementation/)
- [Windows termination signals](https://stackoverflow.com/a/35792192)
- ~~[Get ENUM name from value](https://stackoverflow.com/a/38716384)~~  
  Unused because of required compatibility with lower version python (3.9)

### Networking

- [Dynamically finding host IP address](https://stackoverflow.com/a/28950776)
- [IP Regex](https://ihateregex.io/expr/ip/)

### Database

- [SqlAlchemy session generator](https://stackoverflow.com/a/71053353)
- [Error handling decorator](https://chatgpt.com/share/67a46109-d38c-8005-ac36-677e6511ddcd)

### Platform specific problems

- [Windows sends partial data](https://stackoverflow.com/a/31754798)

### Threading

- [Events to stop scan](https://www.instructables.com/Starting-and-Stopping-Python-Threads-With-Events-i/)