# DirectoryScanReceiver

`DirectoryScanReceiver` is a small TCP server that receives file data over a simple delimiter-based protocol and writes files into an `output` directory.

It is the receiver counterpart to [`DirectoryScanSender`](../DirectoryScanSender), and both projects can work together out of the box with the current default settings.

## Companion Project

- Sender counterpart: [`DirectoryScanSender`](../DirectoryScanSender)
- Shared default TCP port: `7156`

## Shared Protocol

Both projects use the same message format:

```text
<path>|<length>|<content>\r\n\r\n
```

- `path`: file path string sent by the sender
- `length`: declared payload length
- `content`: payload content

Multiple messages can be sent over the same TCP connection, each terminated by `\r\n\r\n`.

## Features

- Listens for TCP connections on port `7156`
- Accepts multiple file messages over a connection
- Writes files to an `output` directory next to the executable
- Creates subdirectories when needed
- Skips existing files (no overwrite)
- Prevents writing outside the `output` directory

## Runtime Behavior

- The server waits for incoming TCP connections.
- Each valid message is parsed and written as one file.
- Empty or invalid messages are ignored.
- The `output` directory is cleared once when the application starts.

Console output includes connection events, received payload sizes, and written file paths.

## Requirements

- .NET SDK with support for `net10.0`

## Build and Run

From the repository root:

```bash
dotnet build
dotnet run --project DirectoryScanReceiver
```

The server prints messages such as:

- `Started Server!`
- `Waiting for data!`

## Test Message Example

Using `nc` (netcat):

```bash
printf 'hello.txt|5|hello\r\n\r\n' | nc 127.0.0.1 7156
```

This writes `hello.txt` into the receiver's `output` directory.

Subdirectories are also supported:

```bash
printf 'subdir/note.txt|11|hello world\r\n\r\n' | nc 127.0.0.1 7156
```

## Notes

- The protocol is simple and delimiter-based.
- The receiver is intended to be used with [`DirectoryScanSender`](../DirectoryScanSender) or another sender that follows the same message format.
- The current defaults match the local `DirectoryScanSender` project (`localhost:7156`).
- The service uses plain TCP and does not include authentication or encryption.

## License and Disclaimer

This project may be used, copied, modified, and shared freely.

It is provided `as is`, without warranty of any kind. The author is not liable for any damages or losses resulting from its use.