nghttp2/src/shrpx_dns_tracker.cc

325 lines
8.8 KiB
C++

/*
* 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) : loop_(loop) {
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 = ev_now(loop_) + 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 = ev_now(loop_) + 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_);
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 < ev_now(loop_)) {
if (LOG_ENABLED(INFO)) {
LOG(INFO) << "DNS entry found for " << dnsq->host
<< ", but it has been expired";
}
auto resolv = std::make_unique<DualDNSResolver>(loop_);
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) {
auto loop = loop_;
ent.resolv->set_complete_cb(
[&ent, loop](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 = ev_now(loop) + 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 = ev_now(loop_);
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