nghttp2/src/shrpx_dns_resolver.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_resolver.h"
#include <cstring>
#include <sys/time.h>
#include "shrpx_log.h"
#include "shrpx_connection.h"
#include "shrpx_config.h"
namespace shrpx {
namespace {
void sock_state_cb(void *data, int s, int read, int write) {
auto resolv = static_cast<DNSResolver *>(data);
if (resolv->get_status(nullptr) != DNSResolverStatus::RUNNING) {
return;
}
if (read) {
resolv->start_rev(s);
} else {
resolv->stop_rev(s);
}
if (write) {
resolv->start_wev(s);
} else {
resolv->stop_wev(s);
}
}
} // namespace
namespace {
void host_cb(void *arg, int status, int timeouts, hostent *hostent) {
auto resolv = static_cast<DNSResolver *>(arg);
resolv->on_result(status, hostent);
}
} // namespace
namespace {
void process_result(DNSResolver *resolv) {
auto cb = resolv->get_complete_cb();
if (!cb) {
return;
}
Address result;
auto status = resolv->get_status(&result);
switch (status) {
case DNSResolverStatus::OK:
case DNSResolverStatus::ERROR:
cb(status, &result);
break;
default:
break;
}
// resolv may be deleted here.
}
} // namespace
namespace {
void readcb(struct ev_loop *loop, ev_io *w, int revents) {
auto resolv = static_cast<DNSResolver *>(w->data);
resolv->on_read(w->fd);
process_result(resolv);
}
} // namespace
namespace {
void writecb(struct ev_loop *loop, ev_io *w, int revents) {
auto resolv = static_cast<DNSResolver *>(w->data);
resolv->on_write(w->fd);
process_result(resolv);
}
} // namespace
namespace {
void timeoutcb(struct ev_loop *loop, ev_timer *w, int revents) {
auto resolv = static_cast<DNSResolver *>(w->data);
resolv->on_timeout();
process_result(resolv);
}
} // namespace
namespace {
void stop_ev(struct ev_loop *loop,
const std::vector<std::unique_ptr<ev_io>> &evs) {
for (auto &w : evs) {
ev_io_stop(loop, w.get());
}
}
} // namespace
DNSResolver::DNSResolver(struct ev_loop *loop)
: result_{},
loop_(loop),
channel_(nullptr),
family_(AF_UNSPEC),
status_(DNSResolverStatus::IDLE) {
ev_timer_init(&timer_, timeoutcb, 0., 0.);
timer_.data = this;
}
DNSResolver::~DNSResolver() {
if (channel_) {
ares_destroy(channel_);
}
stop_ev(loop_, revs_);
stop_ev(loop_, wevs_);
ev_timer_stop(loop_, &timer_);
}
int DNSResolver::resolve(const StringRef &name, int family) {
if (status_ != DNSResolverStatus::IDLE) {
return -1;
}
if (LOG_ENABLED(INFO)) {
LOG(INFO) << "Start resolving host " << name << " in IPv"
<< (family == AF_INET ? "4" : "6");
}
name_ = name;
family_ = family;
int rv;
auto &dnsconf = get_config()->dns;
ares_options opts{};
opts.sock_state_cb = sock_state_cb;
opts.sock_state_cb_data = this;
opts.timeout = static_cast<int>(dnsconf.timeout.lookup * 1000);
opts.tries = dnsconf.max_try;
auto optmask = ARES_OPT_SOCK_STATE_CB | ARES_OPT_TIMEOUTMS | ARES_OPT_TRIES;
ares_channel chan;
rv = ares_init_options(&chan, &opts, optmask);
if (rv != ARES_SUCCESS) {
if (LOG_ENABLED(INFO)) {
LOG(INFO) << "ares_init_options failed: " << ares_strerror(rv);
}
status_ = DNSResolverStatus::ERROR;
return -1;
}
channel_ = chan;
status_ = DNSResolverStatus::RUNNING;
ares_gethostbyname(channel_, name_.c_str(), family_, host_cb, this);
reset_timeout();
return 0;
}
int DNSResolver::on_read(int fd) { return handle_event(fd, ARES_SOCKET_BAD); }
int DNSResolver::on_write(int fd) { return handle_event(ARES_SOCKET_BAD, fd); }
int DNSResolver::on_timeout() {
return handle_event(ARES_SOCKET_BAD, ARES_SOCKET_BAD);
}
int DNSResolver::handle_event(int rfd, int wfd) {
if (status_ == DNSResolverStatus::IDLE) {
return -1;
}
ares_process_fd(channel_, rfd, wfd);
switch (status_) {
case DNSResolverStatus::RUNNING:
reset_timeout();
return 0;
case DNSResolverStatus::OK:
return 0;
case DNSResolverStatus::ERROR:
return -1;
default:
// Unreachable
assert(0);
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abort();
}
}
void DNSResolver::reset_timeout() {
if (status_ != DNSResolverStatus::RUNNING) {
return;
}
timeval tvout;
auto tv = ares_timeout(channel_, nullptr, &tvout);
if (tv == nullptr) {
return;
}
// To avoid that timer_.repeat becomes 0, which makes ev_timer_again
// useless, add tiny fraction of time.
timer_.repeat = tv->tv_sec + tv->tv_usec / 1000000. + 1e-9;
ev_timer_again(loop_, &timer_);
}
DNSResolverStatus DNSResolver::get_status(Address *result) const {
if (status_ != DNSResolverStatus::OK) {
return status_;
}
if (result) {
memcpy(result, &result_, sizeof(result_));
}
return status_;
}
namespace {
void start_ev(std::vector<std::unique_ptr<ev_io>> &evs, struct ev_loop *loop,
int fd, int event, IOCb cb, void *data) {
for (auto &w : evs) {
if (w->fd == fd) {
return;
}
}
for (auto &w : evs) {
if (w->fd == -1) {
ev_io_set(w.get(), fd, event);
ev_io_start(loop, w.get());
return;
}
}
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auto w = std::make_unique<ev_io>();
ev_io_init(w.get(), cb, fd, event);
w->data = data;
ev_io_start(loop, w.get());
evs.emplace_back(std::move(w));
}
} // namespace
namespace {
void stop_ev(std::vector<std::unique_ptr<ev_io>> &evs, struct ev_loop *loop,
int fd, int event) {
for (auto &w : evs) {
if (w->fd == fd) {
ev_io_stop(loop, w.get());
ev_io_set(w.get(), -1, event);
return;
}
}
}
} // namespace
void DNSResolver::start_rev(int fd) {
start_ev(revs_, loop_, fd, EV_READ, readcb, this);
}
void DNSResolver::stop_rev(int fd) { stop_ev(revs_, loop_, fd, EV_READ); }
void DNSResolver::start_wev(int fd) {
start_ev(wevs_, loop_, fd, EV_WRITE, writecb, this);
}
void DNSResolver::stop_wev(int fd) { stop_ev(wevs_, loop_, fd, EV_WRITE); }
void DNSResolver::on_result(int status, hostent *hostent) {
stop_ev(loop_, revs_);
stop_ev(loop_, wevs_);
ev_timer_stop(loop_, &timer_);
if (status != ARES_SUCCESS) {
if (LOG_ENABLED(INFO)) {
LOG(INFO) << "Name lookup for " << name_
<< " failed: " << ares_strerror(status);
}
status_ = DNSResolverStatus::ERROR;
return;
}
auto ap = *hostent->h_addr_list;
if (!ap) {
if (LOG_ENABLED(INFO)) {
LOG(INFO) << "Name lookup for " << name_ << "failed: no address returned";
}
status_ = DNSResolverStatus::ERROR;
return;
}
switch (hostent->h_addrtype) {
case AF_INET:
status_ = DNSResolverStatus::OK;
result_.len = sizeof(result_.su.in);
result_.su.in = {};
result_.su.in.sin_family = AF_INET;
#ifdef HAVE_SOCKADDR_IN_SIN_LEN
result_.su.in.sin_len = sizeof(result_.su.in);
#endif // HAVE_SOCKADDR_IN_SIN_LEN
memcpy(&result_.su.in.sin_addr, ap, sizeof(result_.su.in.sin_addr));
break;
case AF_INET6:
status_ = DNSResolverStatus::OK;
result_.len = sizeof(result_.su.in6);
result_.su.in6 = {};
result_.su.in6.sin6_family = AF_INET6;
#ifdef HAVE_SOCKADDR_IN6_SIN6_LEN
result_.su.in6.sin6_len = sizeof(result_.su.in6);
#endif // HAVE_SOCKADDR_IN6_SIN6_LEN
memcpy(&result_.su.in6.sin6_addr, ap, sizeof(result_.su.in6.sin6_addr));
break;
default:
assert(0);
}
if (status_ == DNSResolverStatus::OK) {
if (LOG_ENABLED(INFO)) {
LOG(INFO) << "Name lookup succeeded: " << name_ << " -> "
<< util::numeric_name(&result_.su.sa, result_.len);
}
return;
}
status_ = DNSResolverStatus::ERROR;
}
void DNSResolver::set_complete_cb(CompleteCb cb) {
completeCb_ = std::move(cb);
}
CompleteCb DNSResolver::get_complete_cb() const { return completeCb_; }
} // namespace shrpx