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construct/include/ircd/net/dns_resolver.h

125 lines
3.8 KiB
C++

// Matrix Construct
//
// Copyright (C) Matrix Construct Developers, Authors & Contributors
// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice is present in all copies. The
// full license for this software is available in the LICENSE file.
//
// This file is not part of the ircd.h precompiled header because it contains
// boost::asio assets which we cannot forward declare. It is part of the
// ircd/asio.h precompiled header.
//
namespace ircd::net::dns
{
struct tag;
struct resolver extern *resolver_instance;
using answers = vector_view<const rfc1035::answer>;
using answers_callback = std::function<void (std::exception_ptr, const tag &, const answers &)>;
constexpr const size_t MAX_COUNT {64};
uint16_t resolver_call(const hostport &, const opts &);
}
struct ircd::net::dns::resolver
{
using header = rfc1035::header;
static conf::item<std::string> servers;
static conf::item<milliseconds> timeout;
static conf::item<milliseconds> send_rate;
static conf::item<size_t> send_burst;
static conf::item<size_t> retry_max;
answers_callback callback;
std::vector<ip::udp::endpoint> server; // The list of active servers
size_t server_next{0}; // Round-robin state to hit servers
ctx::dock dock, done;
ctx::mutex mutex;
std::map<uint16_t, tag> tags; // The active requests
steady_point send_last; // Time of last send
std::deque<uint16_t> sendq; // Queue of frames for rate-limiting
ip::udp::socket ns; // A pollable activity object
// util
void add_server(const ipport &);
void add_server(const string_view &);
void set_servers(const string_view &list);
void set_servers();
// removal (must have lock)
void unqueue(tag &);
void remove(tag &);
decltype(tags)::iterator remove(tag &, const decltype(tags)::iterator &);
void error_one(tag &, const std::exception_ptr &, const bool &remove = true);
void error_one(tag &, const std::system_error &, const bool &remove = true);
void error_all(const std::error_code &, const bool &remove = true);
void cancel_all(const bool &remove = true);
// reception
bool handle_error(const header &, tag &);
void handle_reply(const header &, const const_buffer &body, tag &);
void handle_reply(const ipport &, const header &, const const_buffer &body);
void handle(const ipport &, const mutable_buffer &);
void recv_worker();
ctx::context recv_context;
// submission
void send_query(const ip::udp::endpoint &, tag &);
void queue_query(tag &);
void send_query(tag &);
void submit(tag &);
// timeout
bool check_timeout(const uint16_t &id, tag &, const steady_point &expired);
void check_timeouts(const milliseconds &timeout);
void timeout_worker();
ctx::context timeout_context;
// sendq
void flush(const uint16_t &);
void sendq_work();
void sendq_clear();
void sendq_worker();
ctx::context sendq_context;
template<class... A> tag &set_tag(A&&...);
const_buffer make_query(const mutable_buffer &buf, tag &);
uint16_t operator()(const hostport &, const opts &);
resolver(answers_callback);
~resolver() noexcept;
};
struct ircd::net::dns::tag
{
uint16_t id {0};
hostport hp;
dns::opts opts; // note: invalid after query sent
const_buffer question;
steady_point last {steady_point::min()};
uint8_t tries {0};
uint rcode {0};
ipport server;
char hostbuf[rfc1035::NAME_BUFSIZE];
char qbuf[512];
tag(const hostport &hp, const dns::opts &opts)
:hp{hp}
,opts{opts}
{
this->hp.host = { hostbuf, copy(hostbuf, hp.host) };
this->hp.service = {};
}
tag(tag &&) = delete;
tag(const tag &) = delete;
tag &operator=(tag &&) = delete;
tag &operator=(const tag &) = delete;
};