troll-patrol/src/simulation/censor.rs

use crate::{
    get_date,
    simulation::{bridge::Bridge, state::State},
    PositiveReport,
};

use lox_cli::{get_lox_pub, networking::Networking};
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);
        }
    }

    // Make a bunch of connections and submit positive reports if possible
    async fn flood(&self, state: &State, bridges: &mut HashMap<[u8; 20], Bridge>) {
        // Only do this if Flooding censor
        if self.hides == Hides::Flooding {
            for fingerprint in &self.known_bridges {
                // Only do this if we're blocking the bridge
                if self.speed == Speed::Fast
                    || self.speed == Speed::Lox && self.has_lox_cred(fingerprint)
                    || self.speed == Speed::Random && self.delay_date <= get_date()
                {
                    let bridge = bridges.get_mut(fingerprint).unwrap();
                    let mut rng = rand::thread_rng();
                    let num_connections = rng.gen_range(1000..30000);

                    // Make a bunch of connections to the bridge
                    bridge.censor_flood(&self.country, num_connections);

                    // If we have a lv3+ credential, submit a bunch of
                    // positive reports
                    if self.has_lox_cred(fingerprint) {
                        let lox_pub = get_lox_pub(&state.la_pubkeys);
                        for _ in 0..num_connections {
                            let pr = PositiveReport::from_lox_credential(
                                bridge.fingerprint,
                                None,
                                &self.lox_credentials.get(&bridge.fingerprint).unwrap(),
                                lox_pub,
                                self.country.clone(),
                            )
                            .unwrap();
                            state
                                .tp_net
                                .request("/positivereport".to_string(), pr.to_json().into_bytes())
                                .await;
                        }
                    }
                }
            }
        }
    }

    // TODO: How do we want to do this? We don't want to stop blocking
    // bridges the day after we start.
    fn recompute_delay(&mut self) {
        // Only do this if Random censor
        if self.speed == Speed::Random && self.delay_date <= get_date() {
            // Compute new delay date
            self.delay_date = {
                let mut rng = rand::thread_rng();
                let num: u32 = rng.gen_range(1..365);
                get_date() + num
            }
        }
    }

    pub async fn end_of_day_tasks(
        &mut self,
        state: &State,
        bridges: &mut HashMap<[u8; 20], Bridge>,
    ) {
        if self.hides == Hides::Flooding
            && !(self.speed == Speed::Random && self.delay_date <= get_date())
        {
            self.flood(state, bridges).await;
        }

        // TODO: recompute_delay sometimes
        //self.recompute_delay();
    }
}

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

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

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