stru.rs

//! The RFC 959 File Structure (`STRU`) command
//
// The argument is a single Telnet character code specifying
// file structure described in the Section on Data
// Representation and Storage.
//
// The following codes are assigned for structure:
//
// F - File (no record structure)
// R - Record structure
// P - Page structure
//
// The default structure is File.

use crate::{
    auth::UserDetail,
    server::controlchan::{
        error::ControlChanError,
        handler::{CommandContext, CommandHandler},
        Reply, ReplyCode,
    },
    storage::{Metadata, StorageBackend},
};
use async_trait::async_trait;

/// The parameter the can be given to the `STRU` command. It is used to set the file `STRU`cture to
/// the given structure. This stems from a time where it was common for some operating
/// systems to address i.e. particular records in files, but isn't used a lot these days. We
/// support the command itself for legacy reasons, but will only support the `File` structure.
// Unfortunately Rust doesn't support anonymous enums for now, so we'll have to do with explicit
// command parameter enums for the commands that take mutually exclusive parameters.
#[derive(Debug, PartialEq, Eq, Clone)]
pub enum StruParam {
    /// "Regular" file structure.
    File,
    /// Files are structured in "Records".
    Record,
    /// Files are structured in "Pages".
    Page,
}

#[derive(Debug)]
pub struct Stru {
    params: StruParam,
}

impl Stru {
    pub fn new(params: StruParam) -> Self {
        Stru { params }
    }
}

#[async_trait]
impl<Storage, User> CommandHandler<Storage, User> for Stru
where
    User: UserDetail + 'static,
    Storage: StorageBackend<User> + 'static,
    Storage::Metadata: Metadata,
{
    #[tracing_attributes::instrument]
    async fn handle(&self, _args: CommandContext<Storage, User>) -> Result<Reply, ControlChanError> {
        match &self.params {
            StruParam::File => Ok(Reply::new(ReplyCode::CommandOkay, "In File structure mode")),
            _ => Ok(Reply::new(
                ReplyCode::CommandNotImplementedForParameter,
                "Only File structure mode is supported",
            )),
        }
    }
}