dns_cache.cpp

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/*
 * BastionGuard™
 * Copyright (C) 2025–2026 Calogero Scarnà
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, version 3.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 * BastionGuard™ is a trademark of Calogero Scarnà.
 * The BastionGuard™ name and branding are not licensed under the GPL.
 */
 
 
#include "dns_cache.hpp"
#include <chrono>
#include <iostream>
 
DNSCache &DNSCache::instance() {
    static DNSCache inst;
    return inst;
}
 
bool DNSCache::lookup(const std::string &host, std::vector<std::string> &out) {
    std::lock_guard<std::mutex> lk(mu_);
    auto it = map_.find(host);
    if (it == map_.end()) return false;
 
    auto now = std::chrono::steady_clock::now();
    if (now > it->second.expires) {
        map_.erase(it);
        return false;
    }
 
    out = it->second.addrs;
    return true;
}
 
std::string DNSCache::lookup_one(const std::string &host) {
    std::vector<std::string> addrs;
    if (lookup(host, addrs) && !addrs.empty())
        return addrs.front();
    return {};
}
 
void DNSCache::store(const std::string &host,
                     const std::vector<std::string> &addrs,
                     int ttl_seconds) {
    if (host.empty() || addrs.empty()) return;
 
    DNSResult r;
    r.addrs = addrs;
    int ttl = (ttl_seconds > 0) ? ttl_seconds : default_ttl_;
    auto now = std::chrono::steady_clock::now();
    r.expires = now + std::chrono::seconds(ttl);
 
    std::lock_guard<std::mutex> lk(mu_);
    map_[host] = std::move(r);
}
 
void DNSCache::set_default_ttl(int seconds) {
    std::lock_guard<std::mutex> lk(mu_);
    default_ttl_ = (seconds > 0) ? seconds : 60;
}
 
void DNSCache::clear() {
    std::lock_guard<std::mutex> lk(mu_);
    map_.clear();
}
 
size_t DNSCache::size() const {
    std::lock_guard<std::mutex> lk(mu_);
    return map_.size();
}