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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.
*/
#ifndef SHRPX_DNS_RESOLVER_H
#define SHRPX_DNS_RESOLVER_H
#include "shrpx.h"
#include <sys/socket.h>
#include <netinet/in.h>
#include <vector>
#include <ev.h>
#include <ares.h>
#include "template.h"
#include "network.h"
using namespace nghttp2;
namespace shrpx {
enum class DNSResolverStatus {
// Resolver is in initial status
IDLE,
// Resolver is currently resolving host name
RUNNING,
// Resolver successfully resolved host name
OK,
// Resolver failed to resolve host name
ERROR,
};
// Callback function called when host name lookup is finished.
// |status| is either DNSResolverStatus::OK, or
// DNSResolverStatus::ERROR. If |status| is DNSResolverStatus::OK,
// |result| points to the resolved address. Note that port portion of
// |result| is undefined, and must be initialized by application.
// This callback function is not called if name lookup finishes in
// DNSResolver::resolve() completely. In this case, application
// should call DNSResolver::get_status() to get current status and
// result. In other words, callback is called if get_status() returns
// DNSResolverStatus::RUNNING.
using CompleteCb =
std::function<void(DNSResolverStatus status, const Address *result)>;
// DNSResolver is asynchronous name resolver, backed by c-ares
// library.
class DNSResolver {
public:
DNSResolver(struct ev_loop *loop);
~DNSResolver();
// Starts resolving hostname |name|.
int resolve(const StringRef &name, int family);
// Returns status. If status_ is DNSResolverStatus::SUCCESS &&
// |result| is not nullptr, |*result| is filled.
DNSResolverStatus get_status(Address *result) const;
// Sets callback function when name lookup finishes. The callback
// function is called in a way that it can destroy this DNSResolver.
void set_complete_cb(CompleteCb cb);
CompleteCb get_complete_cb() const;
// Calls these functions when read/write event occurred respectively.
int on_read(int fd);
int on_write(int fd);
int on_timeout();
// Calls this function when DNS query finished.
void on_result(int status, ares_addrinfo *result);
void reset_timeout();
void start_rev(int fd);
void stop_rev(int fd);
void start_wev(int fd);
void stop_wev(int fd);
private:
int handle_event(int rfd, int wfd);
std::vector<std::unique_ptr<ev_io>> revs_, wevs_;
Address result_;
CompleteCb completeCb_;
ev_timer timer_;
StringRef name_;
struct ev_loop *loop_;
// ares_channel is pointer type
ares_channel channel_;
// AF_INET or AF_INET6. AF_INET for A record lookup, and AF_INET6
// for AAAA record lookup.
int family_;
DNSResolverStatus status_;
};
} // namespace shrpx
#endif // SHRPX_DNS_RESOLVER_H
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