dns_util.hpp File Reference

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Functions
bool	resolve_with_cache (const std::string &host, std::vector< std::string > &addrs, int ttl_seconds=0)

Function Documentation

resolve_with_cache()

bool resolve_with_cache ( const std::string & host, std::vector< std::string > & addrs, int ttl_seconds = 0 )

inline

Definition at line 33 of file dns_util.hpp.

                                                                                                      {
    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;
}

References AF_INET, AF_INET6, DNSCache::instance(), resolve_with_cache(), and DNSCache::store().

Referenced by resolve_with_cache().