325 lines
8.8 KiB
C++
325 lines
8.8 KiB
C++
/*
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* nghttp2 - HTTP/2 C Library
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*
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* Copyright (c) 2016 Tatsuhiro Tsujikawa
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#include "shrpx_dns_tracker.h"
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#include "shrpx_config.h"
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#include "shrpx_log.h"
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#include "util.h"
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namespace shrpx {
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namespace {
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void gccb(struct ev_loop *loop, ev_timer *w, int revents) {
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auto dns_tracker = static_cast<DNSTracker *>(w->data);
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dns_tracker->gc();
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}
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} // namespace
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DNSTracker::DNSTracker(struct ev_loop *loop) : loop_(loop) {
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ev_timer_init(&gc_timer_, gccb, 0., 12_h);
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gc_timer_.data = this;
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}
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DNSTracker::~DNSTracker() {
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ev_timer_stop(loop_, &gc_timer_);
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for (auto &p : ents_) {
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auto &qlist = p.second.qlist;
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while (!qlist.empty()) {
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auto head = qlist.head;
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qlist.remove(head);
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head->status = DNSResolverStatus::ERROR;
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head->in_qlist = false;
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// TODO Not sure we should call callback here, or it is even be
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// safe to do that.
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}
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}
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}
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ResolverEntry DNSTracker::make_entry(std::unique_ptr<DualDNSResolver> resolv,
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ImmutableString host,
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DNSResolverStatus status,
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const Address *result) {
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auto &dnsconf = get_config()->dns;
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auto ent = ResolverEntry{};
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ent.resolv = std::move(resolv);
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ent.host = std::move(host);
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ent.status = status;
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switch (status) {
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case DNSResolverStatus::ERROR:
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case DNSResolverStatus::OK:
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ent.expiry = ev_now(loop_) + dnsconf.timeout.cache;
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break;
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default:
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break;
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}
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if (result) {
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ent.result = *result;
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}
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return ent;
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}
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void DNSTracker::update_entry(ResolverEntry &ent,
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std::unique_ptr<DualDNSResolver> resolv,
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DNSResolverStatus status, const Address *result) {
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auto &dnsconf = get_config()->dns;
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ent.resolv = std::move(resolv);
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ent.status = status;
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switch (status) {
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case DNSResolverStatus::ERROR:
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case DNSResolverStatus::OK:
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ent.expiry = ev_now(loop_) + dnsconf.timeout.cache;
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break;
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default:
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break;
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}
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if (result) {
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ent.result = *result;
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}
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}
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DNSResolverStatus DNSTracker::resolve(Address *result, DNSQuery *dnsq) {
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int rv;
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auto it = ents_.find(dnsq->host);
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if (it == std::end(ents_)) {
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if (LOG_ENABLED(INFO)) {
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LOG(INFO) << "DNS entry not found for " << dnsq->host;
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}
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auto resolv = std::make_unique<DualDNSResolver>(loop_);
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auto host_copy =
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ImmutableString{std::begin(dnsq->host), std::end(dnsq->host)};
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auto host = StringRef{host_copy};
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rv = resolv->resolve(host);
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if (rv != 0) {
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if (LOG_ENABLED(INFO)) {
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LOG(INFO) << "Name lookup failed for " << host;
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}
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ents_.emplace(host, make_entry(nullptr, std::move(host_copy),
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DNSResolverStatus::ERROR, nullptr));
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start_gc_timer();
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return DNSResolverStatus::ERROR;
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}
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switch (resolv->get_status(result)) {
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case DNSResolverStatus::ERROR:
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if (LOG_ENABLED(INFO)) {
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LOG(INFO) << "Name lookup failed for " << host;
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}
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ents_.emplace(host, make_entry(nullptr, std::move(host_copy),
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DNSResolverStatus::ERROR, nullptr));
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start_gc_timer();
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return DNSResolverStatus::ERROR;
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case DNSResolverStatus::OK:
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if (LOG_ENABLED(INFO)) {
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LOG(INFO) << "Name lookup succeeded: " << host << " -> "
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<< util::numeric_name(&result->su.sa, result->len);
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}
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ents_.emplace(host, make_entry(nullptr, std::move(host_copy),
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DNSResolverStatus::OK, result));
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start_gc_timer();
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return DNSResolverStatus::OK;
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case DNSResolverStatus::RUNNING: {
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auto p = ents_.emplace(host,
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make_entry(std::move(resolv), std::move(host_copy),
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DNSResolverStatus::RUNNING, nullptr));
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start_gc_timer();
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auto &ent = (*p.first).second;
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add_to_qlist(ent, dnsq);
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return DNSResolverStatus::RUNNING;
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}
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default:
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assert(0);
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}
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}
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auto &ent = (*it).second;
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if (ent.status != DNSResolverStatus::RUNNING && ent.expiry < ev_now(loop_)) {
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if (LOG_ENABLED(INFO)) {
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LOG(INFO) << "DNS entry found for " << dnsq->host
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<< ", but it has been expired";
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}
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auto resolv = std::make_unique<DualDNSResolver>(loop_);
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auto host = StringRef{ent.host};
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rv = resolv->resolve(host);
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if (rv != 0) {
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if (LOG_ENABLED(INFO)) {
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LOG(INFO) << "Name lookup failed for " << host;
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}
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update_entry(ent, nullptr, DNSResolverStatus::ERROR, nullptr);
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return DNSResolverStatus::ERROR;
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}
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switch (resolv->get_status(result)) {
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case DNSResolverStatus::ERROR:
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if (LOG_ENABLED(INFO)) {
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LOG(INFO) << "Name lookup failed for " << host;
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}
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update_entry(ent, nullptr, DNSResolverStatus::ERROR, nullptr);
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return DNSResolverStatus::ERROR;
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case DNSResolverStatus::OK:
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if (LOG_ENABLED(INFO)) {
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LOG(INFO) << "Name lookup succeeded: " << host << " -> "
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<< util::numeric_name(&result->su.sa, result->len);
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}
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update_entry(ent, nullptr, DNSResolverStatus::OK, result);
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return DNSResolverStatus::OK;
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case DNSResolverStatus::RUNNING:
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update_entry(ent, std::move(resolv), DNSResolverStatus::RUNNING, nullptr);
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add_to_qlist(ent, dnsq);
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return DNSResolverStatus::RUNNING;
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default:
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assert(0);
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}
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}
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switch (ent.status) {
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case DNSResolverStatus::RUNNING:
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if (LOG_ENABLED(INFO)) {
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LOG(INFO) << "Waiting for name lookup complete for " << dnsq->host;
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}
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ent.qlist.append(dnsq);
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dnsq->in_qlist = true;
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return DNSResolverStatus::RUNNING;
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case DNSResolverStatus::ERROR:
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if (LOG_ENABLED(INFO)) {
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LOG(INFO) << "Name lookup failed for " << dnsq->host << " (cached)";
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}
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return DNSResolverStatus::ERROR;
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case DNSResolverStatus::OK:
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if (LOG_ENABLED(INFO)) {
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LOG(INFO) << "Name lookup succeeded (cached): " << dnsq->host << " -> "
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<< util::numeric_name(&ent.result.su.sa, ent.result.len);
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}
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if (result) {
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memcpy(result, &ent.result, sizeof(*result));
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}
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return DNSResolverStatus::OK;
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default:
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assert(0);
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abort();
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}
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}
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void DNSTracker::add_to_qlist(ResolverEntry &ent, DNSQuery *dnsq) {
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auto loop = loop_;
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ent.resolv->set_complete_cb(
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[&ent, loop](DNSResolverStatus status, const Address *result) {
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auto &qlist = ent.qlist;
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while (!qlist.empty()) {
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auto head = qlist.head;
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qlist.remove(head);
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head->status = status;
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head->in_qlist = false;
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auto cb = head->cb;
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cb(status, result);
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}
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auto &dnsconf = get_config()->dns;
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ent.resolv.reset();
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ent.status = status;
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ent.expiry = ev_now(loop) + dnsconf.timeout.cache;
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if (ent.status == DNSResolverStatus::OK) {
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ent.result = *result;
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}
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});
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ent.qlist.append(dnsq);
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dnsq->in_qlist = true;
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}
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void DNSTracker::cancel(DNSQuery *dnsq) {
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if (!dnsq->in_qlist) {
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return;
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}
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auto it = ents_.find(dnsq->host);
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if (it == std::end(ents_)) {
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return;
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}
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auto &ent = (*it).second;
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ent.qlist.remove(dnsq);
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dnsq->in_qlist = false;
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}
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void DNSTracker::start_gc_timer() {
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if (ev_is_active(&gc_timer_)) {
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return;
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}
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ev_timer_again(loop_, &gc_timer_);
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}
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void DNSTracker::gc() {
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if (LOG_ENABLED(INFO)) {
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LOG(INFO) << "Starting removing expired DNS cache entries";
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}
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auto now = ev_now(loop_);
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for (auto it = std::begin(ents_); it != std::end(ents_);) {
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auto &ent = (*it).second;
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if (ent.expiry >= now) {
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++it;
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continue;
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}
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it = ents_.erase(it);
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}
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if (ents_.empty()) {
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ev_timer_stop(loop_, &gc_timer_);
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}
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}
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} // namespace shrpx
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