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-rw-r--r--src/shrpx_dns_tracker.cc328
1 files changed, 328 insertions, 0 deletions
diff --git a/src/shrpx_dns_tracker.cc b/src/shrpx_dns_tracker.cc
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+++ b/src/shrpx_dns_tracker.cc
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+/*
+ * nghttp2 - HTTP/2 C Library
+ *
+ * Copyright (c) 2016 Tatsuhiro Tsujikawa
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+#include "shrpx_dns_tracker.h"
+#include "shrpx_config.h"
+#include "shrpx_log.h"
+#include "util.h"
+
+namespace shrpx {
+
+namespace {
+void gccb(struct ev_loop *loop, ev_timer *w, int revents) {
+ auto dns_tracker = static_cast<DNSTracker *>(w->data);
+ dns_tracker->gc();
+}
+} // namespace
+
+DNSTracker::DNSTracker(struct ev_loop *loop, int family)
+ : loop_(loop), family_(family) {
+ ev_timer_init(&gc_timer_, gccb, 0., 12_h);
+ gc_timer_.data = this;
+}
+
+DNSTracker::~DNSTracker() {
+ ev_timer_stop(loop_, &gc_timer_);
+
+ for (auto &p : ents_) {
+ auto &qlist = p.second.qlist;
+ while (!qlist.empty()) {
+ auto head = qlist.head;
+ qlist.remove(head);
+ head->status = DNSResolverStatus::ERROR;
+ head->in_qlist = false;
+ // TODO Not sure we should call callback here, or it is even be
+ // safe to do that.
+ }
+ }
+}
+
+ResolverEntry DNSTracker::make_entry(std::unique_ptr<DualDNSResolver> resolv,
+ ImmutableString host,
+ DNSResolverStatus status,
+ const Address *result) {
+ auto &dnsconf = get_config()->dns;
+
+ auto ent = ResolverEntry{};
+ ent.resolv = std::move(resolv);
+ ent.host = std::move(host);
+ ent.status = status;
+ switch (status) {
+ case DNSResolverStatus::ERROR:
+ case DNSResolverStatus::OK:
+ ent.expiry = std::chrono::steady_clock::now() +
+ util::duration_from(dnsconf.timeout.cache);
+ break;
+ default:
+ break;
+ }
+ if (result) {
+ ent.result = *result;
+ }
+ return ent;
+}
+
+void DNSTracker::update_entry(ResolverEntry &ent,
+ std::unique_ptr<DualDNSResolver> resolv,
+ DNSResolverStatus status, const Address *result) {
+ auto &dnsconf = get_config()->dns;
+
+ ent.resolv = std::move(resolv);
+ ent.status = status;
+ switch (status) {
+ case DNSResolverStatus::ERROR:
+ case DNSResolverStatus::OK:
+ ent.expiry = std::chrono::steady_clock::now() +
+ util::duration_from(dnsconf.timeout.cache);
+ break;
+ default:
+ break;
+ }
+ if (result) {
+ ent.result = *result;
+ }
+}
+
+DNSResolverStatus DNSTracker::resolve(Address *result, DNSQuery *dnsq) {
+ int rv;
+
+ auto it = ents_.find(dnsq->host);
+
+ if (it == std::end(ents_)) {
+ if (LOG_ENABLED(INFO)) {
+ LOG(INFO) << "DNS entry not found for " << dnsq->host;
+ }
+
+ auto resolv = std::make_unique<DualDNSResolver>(loop_, family_);
+ auto host_copy =
+ ImmutableString{std::begin(dnsq->host), std::end(dnsq->host)};
+ auto host = StringRef{host_copy};
+
+ rv = resolv->resolve(host);
+ if (rv != 0) {
+ if (LOG_ENABLED(INFO)) {
+ LOG(INFO) << "Name lookup failed for " << host;
+ }
+
+ ents_.emplace(host, make_entry(nullptr, std::move(host_copy),
+ DNSResolverStatus::ERROR, nullptr));
+
+ start_gc_timer();
+
+ return DNSResolverStatus::ERROR;
+ }
+
+ switch (resolv->get_status(result)) {
+ case DNSResolverStatus::ERROR:
+ if (LOG_ENABLED(INFO)) {
+ LOG(INFO) << "Name lookup failed for " << host;
+ }
+
+ ents_.emplace(host, make_entry(nullptr, std::move(host_copy),
+ DNSResolverStatus::ERROR, nullptr));
+
+ start_gc_timer();
+
+ return DNSResolverStatus::ERROR;
+ case DNSResolverStatus::OK:
+ if (LOG_ENABLED(INFO)) {
+ LOG(INFO) << "Name lookup succeeded: " << host << " -> "
+ << util::numeric_name(&result->su.sa, result->len);
+ }
+
+ ents_.emplace(host, make_entry(nullptr, std::move(host_copy),
+ DNSResolverStatus::OK, result));
+
+ start_gc_timer();
+
+ return DNSResolverStatus::OK;
+ case DNSResolverStatus::RUNNING: {
+ auto p = ents_.emplace(host,
+ make_entry(std::move(resolv), std::move(host_copy),
+ DNSResolverStatus::RUNNING, nullptr));
+
+ start_gc_timer();
+
+ auto &ent = (*p.first).second;
+
+ add_to_qlist(ent, dnsq);
+
+ return DNSResolverStatus::RUNNING;
+ }
+ default:
+ assert(0);
+ }
+ }
+
+ auto &ent = (*it).second;
+
+ if (ent.status != DNSResolverStatus::RUNNING &&
+ ent.expiry < std::chrono::steady_clock::now()) {
+ if (LOG_ENABLED(INFO)) {
+ LOG(INFO) << "DNS entry found for " << dnsq->host
+ << ", but it has been expired";
+ }
+
+ auto resolv = std::make_unique<DualDNSResolver>(loop_, family_);
+ auto host = StringRef{ent.host};
+
+ rv = resolv->resolve(host);
+ if (rv != 0) {
+ if (LOG_ENABLED(INFO)) {
+ LOG(INFO) << "Name lookup failed for " << host;
+ }
+
+ update_entry(ent, nullptr, DNSResolverStatus::ERROR, nullptr);
+
+ return DNSResolverStatus::ERROR;
+ }
+
+ switch (resolv->get_status(result)) {
+ case DNSResolverStatus::ERROR:
+ if (LOG_ENABLED(INFO)) {
+ LOG(INFO) << "Name lookup failed for " << host;
+ }
+
+ update_entry(ent, nullptr, DNSResolverStatus::ERROR, nullptr);
+
+ return DNSResolverStatus::ERROR;
+ case DNSResolverStatus::OK:
+ if (LOG_ENABLED(INFO)) {
+ LOG(INFO) << "Name lookup succeeded: " << host << " -> "
+ << util::numeric_name(&result->su.sa, result->len);
+ }
+
+ update_entry(ent, nullptr, DNSResolverStatus::OK, result);
+
+ return DNSResolverStatus::OK;
+ case DNSResolverStatus::RUNNING:
+ update_entry(ent, std::move(resolv), DNSResolverStatus::RUNNING, nullptr);
+ add_to_qlist(ent, dnsq);
+
+ return DNSResolverStatus::RUNNING;
+ default:
+ assert(0);
+ }
+ }
+
+ switch (ent.status) {
+ case DNSResolverStatus::RUNNING:
+ if (LOG_ENABLED(INFO)) {
+ LOG(INFO) << "Waiting for name lookup complete for " << dnsq->host;
+ }
+ ent.qlist.append(dnsq);
+ dnsq->in_qlist = true;
+ return DNSResolverStatus::RUNNING;
+ case DNSResolverStatus::ERROR:
+ if (LOG_ENABLED(INFO)) {
+ LOG(INFO) << "Name lookup failed for " << dnsq->host << " (cached)";
+ }
+ return DNSResolverStatus::ERROR;
+ case DNSResolverStatus::OK:
+ if (LOG_ENABLED(INFO)) {
+ LOG(INFO) << "Name lookup succeeded (cached): " << dnsq->host << " -> "
+ << util::numeric_name(&ent.result.su.sa, ent.result.len);
+ }
+ if (result) {
+ memcpy(result, &ent.result, sizeof(*result));
+ }
+ return DNSResolverStatus::OK;
+ default:
+ assert(0);
+ abort();
+ }
+}
+
+void DNSTracker::add_to_qlist(ResolverEntry &ent, DNSQuery *dnsq) {
+ ent.resolv->set_complete_cb(
+ [&ent](DNSResolverStatus status, const Address *result) {
+ auto &qlist = ent.qlist;
+ while (!qlist.empty()) {
+ auto head = qlist.head;
+ qlist.remove(head);
+ head->status = status;
+ head->in_qlist = false;
+ auto cb = head->cb;
+ cb(status, result);
+ }
+
+ auto &dnsconf = get_config()->dns;
+
+ ent.resolv.reset();
+ ent.status = status;
+ ent.expiry = std::chrono::steady_clock::now() +
+ util::duration_from(dnsconf.timeout.cache);
+ if (ent.status == DNSResolverStatus::OK) {
+ ent.result = *result;
+ }
+ });
+ ent.qlist.append(dnsq);
+ dnsq->in_qlist = true;
+}
+
+void DNSTracker::cancel(DNSQuery *dnsq) {
+ if (!dnsq->in_qlist) {
+ return;
+ }
+
+ auto it = ents_.find(dnsq->host);
+ if (it == std::end(ents_)) {
+ return;
+ }
+
+ auto &ent = (*it).second;
+ ent.qlist.remove(dnsq);
+ dnsq->in_qlist = false;
+}
+
+void DNSTracker::start_gc_timer() {
+ if (ev_is_active(&gc_timer_)) {
+ return;
+ }
+
+ ev_timer_again(loop_, &gc_timer_);
+}
+
+void DNSTracker::gc() {
+ if (LOG_ENABLED(INFO)) {
+ LOG(INFO) << "Starting removing expired DNS cache entries";
+ }
+
+ auto now = std::chrono::steady_clock::now();
+ for (auto it = std::begin(ents_); it != std::end(ents_);) {
+ auto &ent = (*it).second;
+ if (ent.expiry >= now) {
+ ++it;
+ continue;
+ }
+
+ it = ents_.erase(it);
+ }
+
+ if (ents_.empty()) {
+ ev_timer_stop(loop_, &gc_timer_);
+ }
+}
+
+} // namespace shrpx
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