dns_util.hpp

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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.
 */
 
#pragma once
#include "dns_cache.hpp"
#include <string>
#include <vector>
#include <netdb.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <chrono>
#include <iostream>
#include <cstring>
 
 
inline bool resolve_with_cache(const std::string &host, std::vector<std::string> &addrs, int ttl_seconds = 0) {
    if (DNSCache::instance().lookup(host, addrs)) {
        return true;
    }
 
    struct addrinfo hints, *res = nullptr;
    memset(&hints, 0, sizeof(hints));
    hints.ai_family = AF_UNSPEC;
    hints.ai_socktype = SOCK_STREAM;
 
    auto t0 = std::chrono::steady_clock::now();
    int err = getaddrinfo(host.c_str(), nullptr, &hints, &res);
    auto t1 = std::chrono::steady_clock::now();
    auto ms = std::chrono::duration_cast<std::chrono::milliseconds>(t1 - t0).count();
 
    bool ok = false;
    if (err == 0 && res) {
        for (struct addrinfo *p = res; p != nullptr; p = p->ai_next) {
            char addrbuf[INET6_ADDRSTRLEN] = {0};
            if (p->ai_family == AF_INET) {
                struct sockaddr_in *sa = (struct sockaddr_in *)p->ai_addr;
                if (inet_ntop(AF_INET, &(sa->sin_addr), addrbuf, sizeof(addrbuf)))
                    addrs.emplace_back(addrbuf);
            } else if (p->ai_family == AF_INET6) {
                struct sockaddr_in6 *sa6 = (struct sockaddr_in6 *)p->ai_addr;
                if (inet_ntop(AF_INET6, &(sa6->sin6_addr), addrbuf, sizeof(addrbuf)))
                    addrs.emplace_back(addrbuf);
            }
        }
        ok = !addrs.empty();
    }
    if (res) freeaddrinfo(res);
    if (ok) DNSCache::instance().store(host, addrs, ttl_seconds);
    return ok;
}