troll-patrol/src/simulation/censor.rs

use crate::get_date;

use lox_library::{cred::Lox, scalar_u32};
use rand::Rng;
use std::collections::{HashMap, HashSet};

pub struct Censor {
    pub country: String,
    pub known_bridges: HashSet<[u8; 20]>,
    pub lox_credentials: HashMap<[u8; 20], Lox>,

    // How fast does this censor block bridges after learning about them?
    pub speed: Speed,
    // If censor implements random blocking, this is the date when it
    // will start blocking all the bridges it knows.
    pub delay_date: u32,

    // Does the censor attempt to hide the fact that a bridge has been blocked?
    pub hides: Hides,

    // Does the censor block bridges uniformly across the country?
    pub totality: Totality,
    // If censor implements partial blocking, what percent of
    // connections are blocked? If totality is not partial, this is set
    // to 100%.
    pub partial_blocking_percent: f64,
}

impl Censor {
    pub fn new(country: String, speed: Speed, hides: Hides, totality: Totality) -> Self {
        let mut rng = rand::thread_rng();
        let delay_date = if speed == Speed::Random {
            let num: u32 = rng.gen_range(1..365);
            get_date() + num
        } else {
            0
        };
        let partial_blocking_percent = if totality == Totality::Partial {
            let num: f64 = rng.gen_range(0.0..1.0);
            num
        } else {
            1.0
        };
        Censor {
            country: country,
            known_bridges: HashSet::<[u8; 20]>::new(),
            lox_credentials: HashMap::<[u8; 20], Lox>::new(),
            speed: speed,
            delay_date: delay_date,
            hides: hides,
            totality: totality,
            partial_blocking_percent: partial_blocking_percent,
        }
    }

    pub fn knows_bridge(&self, fingerprint: &[u8; 20]) -> bool {
        self.known_bridges.contains(fingerprint)
    }

    pub fn learn_bridge(&mut self, fingerprint: &[u8; 20]) {
        self.known_bridges.insert(*fingerprint);
    }

    pub fn has_lox_cred(&self, fingerprint: &[u8; 20]) -> bool {
        self.lox_credentials.contains_key(fingerprint)
    }

    pub fn give_lox_cred(&mut self, fingerprint: &[u8; 20], cred: &Lox) {
        // We only need one level 3+ credential per bridge. (This will
        // change if we restrict positive reports to one per bridge per
        // credential.)
        if !self.has_lox_cred(fingerprint) && scalar_u32(&cred.trust_level).unwrap() >= 3 {
            // We want to clone the credential, but that's not allowed,
            // so we're going to serialize it and then deserialize it.
            let cloned_cred = bincode::deserialize(&bincode::serialize(&cred).unwrap()).unwrap();
            self.lox_credentials.insert(*fingerprint, cloned_cred);
        }
    }
}

#[derive(PartialEq)]
pub enum Speed {
    Fast,
    Lox,
    Random,
}

#[derive(PartialEq)]
pub enum Hides {
    Overt,
    Hiding,
    Flooding,
}

#[derive(PartialEq)]
pub enum Totality {
    Full,
    Partial,
    Throttling,
}