troll-patrol/src/lib.rs

use http::status::StatusCode;
use http_body_util::{BodyExt, Empty};
use hyper::{body::Bytes, Body, Client, Method, Request};
use hyper_util::rt::TokioExecutor;
use lazy_static::lazy_static;
//use select::{document::Document, predicate::Name};
use serde::{Deserialize, Serialize};
use sled::Db;
use std::{
    collections::{BTreeMap, HashMap, HashSet},
    fmt,
};
use x25519_dalek::{PublicKey, StaticSecret};

pub mod analysis;
pub mod bridge_verification_info;
pub mod crypto;
pub mod extra_info;
pub mod negative_report;
pub mod positive_report;
pub mod request_handler;

use analysis::Analyzer;
use extra_info::*;
use negative_report::*;
use positive_report::*;

lazy_static! {
    // known country codes based on Tor geoIP database
    // Produced with `cat /usr/share/tor/geoip{,6} | grep -v ^# | grep -o ..$ | sort | uniq | tr '[:upper:]' '[:lower:]' | tr '\n' ',' | sed 's/,/","/g'`
    pub static ref COUNTRY_CODES: HashSet<&'static str> = HashSet::from(["??","ad","ae","af","ag","ai","al","am","ao","ap","aq","ar","as","at","au","aw","ax","az","ba","bb","bd","be","bf","bg","bh","bi","bj","bl","bm","bn","bo","bq","br","bs","bt","bv","bw","by","bz","ca","cc","cd","cf","cg","ch","ci","ck","cl","cm","cn","co","cr","cs","cu","cv","cw","cx","cy","cz","de","dj","dk","dm","do","dz","ec","ee","eg","eh","er","es","et","eu","fi","fj","fk","fm","fo","fr","ga","gb","gd","ge","gf","gg","gh","gi","gl","gm","gn","gp","gq","gr","gs","gt","gu","gw","gy","hk","hm","hn","hr","ht","hu","id","ie","il","im","in","io","iq","ir","is","it","je","jm","jo","jp","ke","kg","kh","ki","km","kn","kp","kr","kw","ky","kz","la","lb","lc","li","lk","lr","ls","lt","lu","lv","ly","ma","mc","md","me","mf","mg","mh","mk","ml","mm","mn","mo","mp","mq","mr","ms","mt","mu","mv","mw","mx","my","mz","na","nc","ne","nf","ng","ni","nl","no","np","nr","nu","nz","om","pa","pe","pf","pg","ph","pk","pl","pm","pn","pr","ps","pt","pw","py","qa","re","ro","rs","ru","rw","sa","sb","sc","sd","se","sg","sh","si","sj","sk","sl","sm","sn","so","sr","ss","st","sv","sx","sy","sz","tc","td","tf","tg","th","tj","tk","tl","tm","tn","to","tr","tt","tv","tw","tz","ua","ug","um","us","uy","uz","va","vc","ve","vg","vi","vn","vu","wf","ws","ye","yt","za","zm","zw"]);
}

/// We will accept reports up to this many days old.
pub const MAX_BACKDATE: u32 = 3;

/// Get Julian date
pub fn get_date() -> u32 {
    time::OffsetDateTime::now_utc()
        .date()
        .to_julian_day()
        .try_into()
        .unwrap()
}

#[derive(Clone, Copy, Debug, Eq, PartialEq, Ord, PartialOrd, Serialize, Deserialize)]
pub enum BridgeDistributor {
    Lox,
}

/// All the info for a bridge, to be stored in the database
#[derive(Serialize, Deserialize)]
pub struct BridgeInfo {
    /// hashed fingerprint (SHA-1 hash of 20-byte bridge ID)
    pub fingerprint: [u8; 20],

    /// nickname of bridge (probably not necessary)
    pub nickname: String,

    /// first Julian date we started collecting data on this bridge
    pub first_seen: u32,

    /// map of countries to data for this bridge in that country
    pub info_by_country: HashMap<String, BridgeCountryInfo>,
}

impl BridgeInfo {
    pub fn new(fingerprint: [u8; 20], nickname: &String) -> Self {
        Self {
            fingerprint: fingerprint,
            nickname: nickname.to_string(),
            first_seen: get_date(),
            info_by_country: HashMap::<String, BridgeCountryInfo>::new(),
        }
    }
}

impl fmt::Display for BridgeInfo {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let mut str = format!(
            "fingerprint:{}\n",
            array_bytes::bytes2hex("", self.fingerprint).as_str()
        );
        str.push_str(format!("nickname: {}\n", self.nickname).as_str());
        str.push_str(format!("first_seen: {}\n", self.first_seen).as_str());
        str.push_str("info_by_country:");
        for country in self.info_by_country.keys() {
            str.push_str(format!("\n  country: {}", country).as_str());
            let country_info = self.info_by_country.get(country).unwrap();
            for line in country_info.to_string().lines() {
                str.push_str(format!("\n  {}", line).as_str());
            }
        }
        write!(f, "{}", str)
    }
}

#[derive(Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Serialize, Deserialize)]
pub enum BridgeInfoType {
    BridgeIps,
    NegativeReports,
    PositiveReports,
}

/// Information about bridge reachability from a given country
#[derive(Serialize, Deserialize)]
pub struct BridgeCountryInfo {
    pub info_by_day: BTreeMap<u32, BTreeMap<BridgeInfoType, u32>>,
    pub blocked: bool,
}

impl BridgeCountryInfo {
    pub fn new() -> Self {
        Self {
            info_by_day: BTreeMap::<u32, BTreeMap<BridgeInfoType, u32>>::new(),
            blocked: false,
        }
    }

    pub fn add_info(&mut self, info_type: BridgeInfoType, date: u32, count: u32) {
        if self.info_by_day.contains_key(&date) {
            let info = self.info_by_day.get_mut(&date).unwrap();
            if !info.contains_key(&info_type) {
                info.insert(info_type, count);
            } else if info_type == BridgeInfoType::BridgeIps {
                if *info.get(&info_type).unwrap() < count {
                    // Use highest value we've seen today
                    info.insert(info_type, count);
                }
            } else {
                // Add count to previous count for reports
                let new_count = info.get(&info_type).unwrap() + count;
                info.insert(info_type, new_count);
            }
        } else {
            let mut info = BTreeMap::<BridgeInfoType, u32>::new();
            info.insert(info_type, count);
            self.info_by_day.insert(date, info);
        }
    }
}

impl fmt::Display for BridgeCountryInfo {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        let mut str = String::from("info:");
        for date in self.info_by_day.keys() {
            let info = self.info_by_day.get(date).unwrap();
            let ip_count = match info.get(&BridgeInfoType::BridgeIps) {
                Some(v) => v,
                None => &0,
            };
            let nr_count = match info.get(&BridgeInfoType::NegativeReports) {
                Some(v) => v,
                None => &0,
            };
            let pr_count = match info.get(&BridgeInfoType::PositiveReports) {
                Some(v) => v,
                None => &0,
            };
            if ip_count > &0 || nr_count > &0 || pr_count > &0 {
                str.push_str(
                    format!(
                        "\n  date: {}\n    connections: {}\n    negative reports: {}\n    positive reports: {}",
                        date,
                        ip_count,
                        nr_count,
                        pr_count,
                    )
                    .as_str(),
                );
            }
        }
        write!(f, "{}", str)
    }
}

/// We store a set of all known bridges so that we can later iterate over them.
/// This function just adds a bridge fingerprint to that set.
pub fn add_bridge_to_db(db: &Db, fingerprint: [u8; 20]) {
    let mut bridges = match db.get("bridges").unwrap() {
        Some(v) => bincode::deserialize(&v).unwrap(),
        None => HashSet::<[u8; 20]>::new(),
    };
    bridges.insert(fingerprint);
    db.insert("bridges", bincode::serialize(&bridges).unwrap())
        .unwrap();
}

// Download a webpage and return it as a string
pub async fn download(url: &str) -> Result<String, Box<dyn std::error::Error + Send + Sync>> {
    let https = hyper_rustls::HttpsConnectorBuilder::new()
        .with_native_roots()
        .expect("no native root CA certificates found")
        .https_only()
        .enable_http1()
        .build();

    let client: hyper_util::client::legacy::Client<_, Empty<Bytes>> =
        hyper_util::client::legacy::Client::builder(TokioExecutor::new()).build(https);

    println!("Downloading {}", url);
    let mut res = client.get(url.parse()?).await?;
    assert_eq!(res.status(), StatusCode::OK);
    let mut body_str = String::default();
    while let Some(next) = res.frame().await {
        let frame = next?;
        if let Some(chunk) = frame.data_ref() {
            body_str.push_str(&String::from_utf8(chunk.to_vec())?);
        }
    }
    Ok(body_str)
}

// Process extra-infos

/// Adds the extra-info data for a single bridge to the database. If the
/// database already contains an extra-info for this bridge for thid date,
/// but this extra-info contains different data for some reason, use the
/// greater count of connections from each country.
pub fn add_extra_info_to_db(db: &Db, extra_info: ExtraInfo) {
    let fingerprint = extra_info.fingerprint;
    let mut bridge_info = match db.get(fingerprint).unwrap() {
        Some(v) => bincode::deserialize(&v).unwrap(),
        None => {
            add_bridge_to_db(&db, fingerprint);
            BridgeInfo::new(fingerprint, &extra_info.nickname)
        }
    };
    for country in extra_info.bridge_ips.keys() {
        if bridge_info.info_by_country.contains_key::<String>(country) {
            bridge_info
                .info_by_country
                .get_mut(country)
                .unwrap()
                .add_info(
                    BridgeInfoType::BridgeIps,
                    extra_info.date,
                    *extra_info.bridge_ips.get(country).unwrap(),
                );
        } else {
            // No existing entry; make a new one.
            let mut bridge_country_info = BridgeCountryInfo::new();
            bridge_country_info.add_info(
                BridgeInfoType::BridgeIps,
                extra_info.date,
                *extra_info.bridge_ips.get(country).unwrap(),
            );
            bridge_info
                .info_by_country
                .insert(country.to_string(), bridge_country_info);
        }
    }
    // Commit changes to database
    db.insert(fingerprint, bincode::serialize(&bridge_info).unwrap())
        .unwrap();
}

/// Download new extra-infos files and add their data to the database
pub async fn update_extra_infos(
    db: &Db,
    base_url: &str,
) -> Result<(), Box<dyn std::error::Error + Send + Sync>> {
    // Track which files have been processed. This is slightly redundant
    // because we're only downloading files we don't already have, but it
    // might be a good idea to check in case we downloaded a file but didn't
    // process it for some reason.
    let mut processed_extra_infos_files = match db.get(b"extra_infos_files").unwrap() {
        Some(v) => bincode::deserialize(&v).unwrap(),
        None => HashSet::<String>::new(),
    };

    let dir_page = download(base_url).await?;

    // Causes Send issues, so use solution below instead
    //let doc = Document::from(dir_page.as_str());
    //let links = doc.find(Name("a")).filter_map(|n| n.attr("href"));

    // Alternative, less robust solution
    let mut links = HashSet::<String>::new();
    for line in dir_page.lines() {
        let begin_match = "<a href=\"";
        let end_match = "\">";
        if line.contains(begin_match) {
            let link = &line[line.find(begin_match).unwrap() + begin_match.len()..];
            if link.contains(end_match) {
                let link = &link[0..link.find(end_match).unwrap()];
                links.insert(link.to_string());
            }
        }
    }

    let mut new_extra_infos = HashSet::<ExtraInfo>::new();

    // We should now have an iterable collection of links to consider downloading.
    for link in links {
        if link.ends_with("-extra-infos") && !processed_extra_infos_files.contains(&link) {
            let extra_infos_url = format!("{}{}", base_url, link);
            let extra_info_str = download(&extra_infos_url).await?;
            //ExtraInfo::parse_file(&extra_info_str, &mut new_extra_infos);
            let extra_infos = ExtraInfo::parse_file(&extra_info_str);
            new_extra_infos.extend(extra_infos);
            processed_extra_infos_files.insert(link);
        }
    }

    // Add new extra-infos data to database
    for extra_info in new_extra_infos {
        add_extra_info_to_db(&db, extra_info);
    }

    // Store which files we've already downloaded and processed
    db.insert(
        b"extra_infos_files",
        bincode::serialize(&processed_extra_infos_files).unwrap(),
    )
    .unwrap();

    Ok(())
}

// Process negative reports

/// If there is already a negative report ECDH key for this date, return None.
/// Otherwise, generate a new keypair, save the secret part in the db, and
/// return the public part.
pub fn new_negative_report_key(db: &Db, date: u32) -> Option<PublicKey> {
    let mut nr_keys = if !db.contains_key("nr-keys").unwrap() {
        BTreeMap::<u32, StaticSecret>::new()
    } else {
        match bincode::deserialize(&db.get("nr-keys").unwrap().unwrap()) {
            Ok(v) => v,
            Err(_) => BTreeMap::<u32, StaticSecret>::new(),
        }
    };
    if nr_keys.contains_key(&date) {
        None
    } else {
        let mut rng = rand::thread_rng();
        let secret = StaticSecret::random_from_rng(&mut rng);
        let public = PublicKey::from(&secret);
        nr_keys.insert(date, secret);
        db.insert("nr-keys", bincode::serialize(&nr_keys).unwrap())
            .unwrap();
        Some(public)
    }
}

/// Receive an encrypted negative report. Attempt to decrypt it and if
/// successful, add it to the database to be processed later.
pub fn handle_encrypted_negative_report(db: &Db, enc_report: EncryptedNegativeReport) {
    if db.contains_key("nr-keys").unwrap() {
        let nr_keys: BTreeMap<u32, StaticSecret> =
            match bincode::deserialize(&db.get("nr-keys").unwrap().unwrap()) {
                Ok(map) => map,
                Err(_) => {
                    return;
                }
            };
        if nr_keys.contains_key(&enc_report.date) {
            let secret = nr_keys.get(&enc_report.date).unwrap();
            let nr = match enc_report.decrypt(&secret) {
                Ok(nr) => nr,
                Err(_) => {
                    return;
                }
            };
            save_negative_report_to_process(&db, nr);
        }
    }
}

/// We store to-be-processed negative reports as a vector. Add this NR
/// to that vector (or create a new vector if necessary)
pub fn save_negative_report_to_process(db: &Db, nr: NegativeReport) {
    // TODO: Purge these database entries sometimes
    let mut nonces = match db.get(format!("nonces_{}", &nr.date)).unwrap() {
        Some(v) => bincode::deserialize(&v).unwrap(),
        None => HashSet::<[u8; 32]>::new(),
    };

    // Just ignore the report if we've seen the nonce before
    if nonces.insert(nr.nonce) {
        db.insert(
            format!("nonces_{}", &nr.date),
            bincode::serialize(&nonces).unwrap(),
        )
        .unwrap();
        let mut reports = match db.get("nrs-to-process").unwrap() {
            Some(v) => bincode::deserialize(&v).unwrap(),
            None => BTreeMap::<String, Vec<SerializableNegativeReport>>::new(),
        };
        // Store to-be-processed reports with key [fingerprint]_[country]_[date]
        let map_key = format!(
            "{}_{}_{}",
            array_bytes::bytes2hex("", &nr.fingerprint),
            &nr.country,
            &nr.date,
        );
        if reports.contains_key(&map_key) {
            reports
                .get_mut(&map_key)
                .unwrap()
                .push(nr.to_serializable_report());
        } else {
            let mut nrs = Vec::<SerializableNegativeReport>::new();
            nrs.push(nr.to_serializable_report());
            reports.insert(map_key, nrs);
        }
        // Commit changes to database
        db.insert("nrs-to-process", bincode::serialize(&reports).unwrap())
            .unwrap();
    }
}

/// Sends a collection of negative reports to the Lox Authority and returns the
/// number of valid reports returned by the server. The negative reports in the
/// collection should all have the same bridge fingerprint, date, country, and
/// distributor.
pub async fn verify_negative_reports(
    distributors: &BTreeMap<BridgeDistributor, String>,
    reports: &Vec<SerializableNegativeReport>,
) -> u32 {
    // Don't make a network call if we don't have any reports anyway
    if reports.is_empty() {
        return 0;
    }
    // Get one report, assume the rest have the same distributor
    let first_report = &reports[0];
    let distributor = first_report.distributor;
    let client = Client::new();
    let uri: String = (distributors.get(&distributor).unwrap().to_owned() + "/verifynegative")
        .parse()
        .unwrap();
    let req = Request::builder()
        .method(Method::POST)
        .uri(uri)
        .body(Body::from(serde_json::to_string(&reports).unwrap()))
        .unwrap();
    let resp = client.request(req).await.unwrap();
    let buf = hyper::body::to_bytes(resp).await.unwrap();
    serde_json::from_slice(&buf).unwrap()
}

/// Process today's negative reports and store the count of verified reports in
/// the database.
pub async fn update_negative_reports(db: &Db, distributors: &BTreeMap<BridgeDistributor, String>) {
    let mut all_negative_reports = match db.get("nrs-to-process").unwrap() {
        Some(v) => bincode::deserialize(&v).unwrap(),
        None => BTreeMap::<String, Vec<SerializableNegativeReport>>::new(),
    };
    // Key is [fingerprint]_[country]_[date]
    for bridge_country_date in all_negative_reports.keys() {
        let reports = all_negative_reports.get(bridge_country_date).unwrap();
        if !reports.is_empty() {
            let first_report = &reports[0];
            let fingerprint = first_report.fingerprint;
            let date = first_report.date;
            let country = first_report.country.clone();
            let count_valid = verify_negative_reports(&distributors, reports).await;

            // Get bridge info or make new one
            let mut bridge_info = match db.get(fingerprint).unwrap() {
                Some(v) => bincode::deserialize(&v).unwrap(),
                None => {
                    // This case shouldn't happen unless the bridge hasn't
                    // published any bridge stats.
                    add_bridge_to_db(&db, fingerprint);
                    BridgeInfo::new(fingerprint, &String::default())
                }
            };

            // Add the new report count to it
            if bridge_info.info_by_country.contains_key(&country) {
                let bridge_country_info = bridge_info.info_by_country.get_mut(&country).unwrap();
                bridge_country_info.add_info(BridgeInfoType::NegativeReports, date, count_valid);
            } else {
                // No existing entry; make a new one.
                let mut bridge_country_info = BridgeCountryInfo::new();
                bridge_country_info.add_info(BridgeInfoType::NegativeReports, date, count_valid);
                bridge_info
                    .info_by_country
                    .insert(country, bridge_country_info);
            }
            // Commit changes to database
            db.insert(fingerprint, bincode::serialize(&bridge_info).unwrap())
                .unwrap();
        }
    }
    // TODO: Would it be cheaper to just recreate it?
    all_negative_reports.clear();
    // Remove the now-processed reports from the database
    db.insert(
        "nrs-to-process",
        bincode::serialize(&all_negative_reports).unwrap(),
    )
    .unwrap();
}

// Process positive reports

/// We store to-be-processed positive reports as a vector. Add this PR
/// to that vector (or create a new vector if necessary).
pub fn save_positive_report_to_process(db: &Db, pr: PositiveReport) {
    let mut reports = match db.get("prs-to-process").unwrap() {
        Some(v) => bincode::deserialize(&v).unwrap(),
        None => BTreeMap::<String, Vec<SerializablePositiveReport>>::new(),
    };
    // Store to-be-processed reports with key [fingerprint]_[country]_[date]
    let map_key = format!(
        "{}_{}_{}",
        array_bytes::bytes2hex("", &pr.fingerprint),
        &pr.country,
        &pr.date,
    );
    if reports.contains_key(&map_key) {
        reports
            .get_mut(&map_key)
            .unwrap()
            .push(pr.to_serializable_report());
    } else {
        let mut prs = Vec::<SerializablePositiveReport>::new();
        prs.push(pr.to_serializable_report());
        reports.insert(map_key, prs);
    }
    // Commit changes to database
    db.insert("prs-to-process", bincode::serialize(&reports).unwrap())
        .unwrap();
}

/// Sends a collection of positive reports to the Lox Authority and returns the
/// number of valid reports returned by the server. The positive reports in the
/// collection should all have the same bridge fingerprint, date, and country.
pub async fn verify_positive_reports(
    distributors: &BTreeMap<BridgeDistributor, String>,
    reports: &Vec<SerializablePositiveReport>,
) -> u32 {
    // Don't make a network call if we don't have any reports anyway
    if reports.is_empty() {
        return 0;
    }
    let client = Client::new();
    let uri: String = (distributors
        .get(&BridgeDistributor::Lox)
        .unwrap()
        .to_owned()
        + "/verifypositive")
        .parse()
        .unwrap();
    let req = Request::builder()
        .method(Method::POST)
        .uri(uri)
        .body(Body::from(serde_json::to_string(&reports).unwrap()))
        .unwrap();
    let resp = client.request(req).await.unwrap();
    let buf = hyper::body::to_bytes(resp).await.unwrap();
    serde_json::from_slice(&buf).unwrap()
}

/// Process today's positive reports and store the count of verified reports in
/// the database.
pub async fn update_positive_reports(db: &Db, distributors: &BTreeMap<BridgeDistributor, String>) {
    let mut all_positive_reports = match db.get("prs-to-process").unwrap() {
        Some(v) => bincode::deserialize(&v).unwrap(),
        None => BTreeMap::<String, Vec<SerializablePositiveReport>>::new(),
    };
    // Key is [fingerprint]_[country]_[date]
    for bridge_country_date in all_positive_reports.keys() {
        let reports = all_positive_reports.get(bridge_country_date).unwrap();
        if !reports.is_empty() {
            let first_report = &reports[0];
            let fingerprint = first_report.fingerprint;
            let date = first_report.date;
            let country = first_report.country.clone();
            let count_valid = verify_positive_reports(&distributors, reports).await;

            // Get bridge info or make new one
            let mut bridge_info = match db.get(fingerprint).unwrap() {
                Some(v) => bincode::deserialize(&v).unwrap(),
                None => {
                    // This case shouldn't happen unless the bridge hasn't
                    // published any bridge stats.
                    add_bridge_to_db(&db, fingerprint);
                    BridgeInfo::new(fingerprint, &String::default())
                }
            };

            // Add the new report count to it
            if bridge_info.info_by_country.contains_key(&country) {
                let bridge_country_info = bridge_info.info_by_country.get_mut(&country).unwrap();
                bridge_country_info.add_info(BridgeInfoType::PositiveReports, date, count_valid);
            } else {
                // No existing entry; make a new one.
                let mut bridge_country_info = BridgeCountryInfo::new();
                bridge_country_info.add_info(BridgeInfoType::PositiveReports, date, count_valid);
                bridge_info
                    .info_by_country
                    .insert(country, bridge_country_info);
            }
            // Commit changes to database
            db.insert(fingerprint, bincode::serialize(&bridge_info).unwrap())
                .unwrap();
        }
    }
    // TODO: Would it be cheaper to just recreate it?
    all_positive_reports.clear();
    // Remove the now-processed reports from the database
    db.insert(
        "prs-to-process",
        bincode::serialize(&all_positive_reports).unwrap(),
    )
    .unwrap();
}

// Verdict on bridge reachability

/// Guess which countries block a bridge. This function returns a map of new
/// blockages (fingerprint : set of countries which block the bridge)
pub fn guess_blockages(
    db: &Db,
    analyzer: &dyn Analyzer,
    confidence: f64,
) -> HashMap<[u8; 20], HashSet<String>> {
    // Map of bridge fingerprint to set of countries which newly block it
    let mut blockages = HashMap::<[u8; 20], HashSet<String>>::new();

    // Get list of bridges from database
    let bridges = match db.get("bridges").unwrap() {
        Some(v) => bincode::deserialize(&v).unwrap(),
        None => HashSet::<[u8; 20]>::new(),
    };

    // Guess for each bridge
    for fingerprint in bridges {
        let mut bridge_info: BridgeInfo =
            bincode::deserialize(&db.get(fingerprint).unwrap().unwrap()).unwrap();
        let mut new_blockages = HashSet::<String>::new();
        let blocked_in = analysis::blocked_in(analyzer, &bridge_info, confidence, get_date());
        for country in blocked_in {
            let bridge_country_info = bridge_info.info_by_country.get_mut(&country).unwrap();
            if !bridge_country_info.blocked {
                new_blockages.insert(country.to_string());
                // Mark bridge as blocked when db gets updated
                bridge_country_info.blocked = true;
            }
        }
        blockages.insert(fingerprint, new_blockages);

        // Commit changes to database
        db.insert(fingerprint, bincode::serialize(&bridge_info).unwrap())
            .unwrap();
    }

    // Return map of new blockages
    blockages
}

/// Report blocked bridges to bridge distributor
pub async fn report_blockages(
    distributors: &BTreeMap<BridgeDistributor, String>,
    blockages: HashMap<[u8; 20], HashSet<String>>,
) {
    // For now, only report to Lox
    // TODO: Support more distributors
    let uri: String = (distributors
        .get(&BridgeDistributor::Lox)
        .unwrap()
        .to_owned()
        + "/reportblocked")
        .parse()
        .unwrap();

    // Convert map keys from [u8; 20] to 40-character hex strings
    let mut blockages_str = HashMap::<String, HashSet<String>>::new();
    for (fingerprint, countries) in blockages {
        let fpr_string = array_bytes::bytes2hex("", fingerprint);
        blockages_str.insert(fpr_string, countries);
    }

    // Report blocked bridges to bridge distributor
    let client = Client::new();
    let req = Request::builder()
        .method(Method::POST)
        .uri(uri)
        .body(Body::from(serde_json::to_string(&blockages_str).unwrap()))
        .unwrap();
    let resp = client.request(req).await.unwrap();
    let buf = hyper::body::to_bytes(resp).await.unwrap();
    let resp_str: String = serde_json::from_slice(&buf).unwrap();
    assert_eq!("OK", resp_str);
}

// Unit tests
#[cfg(test)]
mod tests;