mirror of
https://github.com/matrix-construct/construct
synced 2024-10-31 02:48:58 +01:00
864 lines
17 KiB
C++
864 lines
17 KiB
C++
// Matrix Construct
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//
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// Copyright (C) Matrix Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2018 Jason Volk <jason@zemos.net>
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//
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// Permission to use, copy, modify, and/or distribute this software for any
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// purpose with or without fee is hereby granted, provided that the above
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// copyright notice and this permission notice is present in all copies. The
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// full license for this software is available in the LICENSE file.
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#include <ircd/asio.h>
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#include "s_dns.h"
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#include "s_dns_resolver.h"
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decltype(ircd::net::dns::resolver)
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ircd::net::dns::resolver;
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decltype(ircd::net::dns::resolver::servers)
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ircd::net::dns::resolver::servers
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{
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{
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{ "name", "ircd.net.dns.resolver.servers" },
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{ "default", "4.2.2.1;4.2.2.2;4.2.2.3;4.2.2.4;4.2.2.5;4.2.2.6" },
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}, []
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{
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if(bool(ircd::net::dns::resolver))
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ircd::net::dns::resolver->set_servers();
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}
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};
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decltype(ircd::net::dns::resolver::timeout)
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ircd::net::dns::resolver::timeout
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{
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{ "name", "ircd.net.dns.resolver.timeout" },
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{ "default", 10000L },
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};
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decltype(ircd::net::dns::resolver::send_rate)
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ircd::net::dns::resolver::send_rate
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{
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{ "name", "ircd.net.dns.resolver.send_rate" },
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{ "default", 60L },
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};
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decltype(ircd::net::dns::resolver::send_burst)
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ircd::net::dns::resolver::send_burst
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{
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{ "name", "ircd.net.dns.resolver.send_burst" },
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{ "default", 8L },
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};
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decltype(ircd::net::dns::resolver::retry_max)
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ircd::net::dns::resolver::retry_max
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{
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{ "name", "ircd.net.dns.resolver.retry_max" },
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{ "default", 4L },
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};
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//
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// interface
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//
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void
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ircd::net::dns::resolver_init()
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{
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assert(!ircd::net::dns::resolver);
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ircd::net::dns::resolver = new typename ircd::net::dns::resolver{};
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}
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void
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ircd::net::dns::resolver_fini()
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{
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delete ircd::net::dns::resolver;
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ircd::net::dns::resolver = nullptr;
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}
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void
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ircd::net::dns::resolver_call(const hostport &hp,
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const opts &opts,
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callback &&cb)
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{
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if(unlikely(!resolver))
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throw error
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{
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"Cannot resolve '%s': resolver unavailable.",
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host(hp)
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};
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auto &resolver{*dns::resolver};
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if(unlikely(!resolver.ns.is_open()))
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throw error
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{
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"Cannot resolve '%s': resolver is closed.",
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host(hp)
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};
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resolver(hp, opts, std::move(cb));
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}
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//
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// resolver::resolver
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//
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ircd::net::dns::resolver::resolver()
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:ns{ios::get()}
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,reply
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{
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64_KiB // worst-case UDP datagram size
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}
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,timeout_context
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{
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"dnsres T", 64_KiB, std::bind(&resolver::timeout_worker, this), context::POST
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}
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,sendq_context
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{
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"dnsres S", 64_KiB, std::bind(&resolver::sendq_worker, this), context::POST
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}
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{
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ns.open(ip::udp::v4());
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ns.non_blocking(true);
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set_servers();
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set_handle();
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}
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ircd::net::dns::resolver::~resolver()
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noexcept
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{
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ns.close();
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sendq_context.terminate();
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timeout_context.terminate();
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while(!tags.empty())
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{
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log::warning
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{
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log, "Waiting for %zu unfinished DNS resolutions", tags.size()
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};
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ctx::sleep(3);
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}
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assert(tags.empty());
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}
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__attribute__((noreturn))
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void
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ircd::net::dns::resolver::sendq_worker()
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{
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while(1)
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{
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dock.wait([this]
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{
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assert(sendq.empty() || !tags.empty());
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return !sendq.empty();
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});
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if(tags.size() > size_t(send_burst))
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ctx::sleep(milliseconds(send_rate));
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sendq_work();
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}
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}
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void
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ircd::net::dns::resolver::sendq_work()
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{
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assert(!sendq.empty());
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assert(sendq.size() < 65535);
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assert(sendq.size() <= tags.size());
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const unwind::nominal::assertion na;
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const uint16_t next(sendq.front());
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sendq.pop_front();
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flush(next);
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}
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void
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ircd::net::dns::resolver::flush(const uint16_t &next)
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try
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{
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auto &tag
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{
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tags.at(next)
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};
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send_query(tag);
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}
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catch(const std::out_of_range &e)
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{
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log::error
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{
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log, "Queued tag id[%u] is no longer mapped", next
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};
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}
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void
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ircd::net::dns::resolver::timeout_worker()
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try
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{
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while(1)
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{
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dock.wait([this]
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{
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return !tags.empty();
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});
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ctx::sleep(milliseconds(timeout));
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check_timeouts(milliseconds(timeout));
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}
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}
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catch(const ctx::terminated &)
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{
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cancel_all_tags();
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}
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void
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ircd::net::dns::resolver::cancel_all_tags()
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{
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static const std::system_error ec
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{
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make_error_code(std::errc::operation_canceled)
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};
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if(!tags.empty())
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log::dwarning
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{
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log, "Attempting to cancel all %zu pending tags.", tags.size()
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};
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for(auto &p : tags)
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post_error(p.second, ec);
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}
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void
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ircd::net::dns::resolver::check_timeouts(const milliseconds &timeout)
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{
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const auto cutoff
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{
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now<steady_point>() - timeout
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};
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auto it(begin(tags));
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while(it != end(tags))
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{
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const auto &id(it->first);
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auto &tag(it->second);
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if(check_timeout(id, tag, cutoff))
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it = tags.erase(it);
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else
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++it;
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}
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}
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bool
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ircd::net::dns::resolver::check_timeout(const uint16_t &id,
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tag &tag,
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const steady_point &cutoff)
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{
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if(tag.last == steady_point::min())
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return false;
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if(tag.last > cutoff)
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return false;
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log::warning
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{
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log, "DNS timeout id:%u on attempt %u of %u '%s'",
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id,
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tag.tries,
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size_t(retry_max),
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host(tag.hp)
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};
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tag.last = steady_point::min();
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if(tag.tries < size_t(retry_max))
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{
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submit(tag);
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return false;
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}
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static const std::system_error ec
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{
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make_error_code(std::errc::timed_out)
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};
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post_error(tag, ec);
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return true;
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}
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void
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ircd::net::dns::resolver::post_error(tag &tag,
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const std::system_error &ec)
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{
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// We ignore this request to post an error here if the tag has no callback
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// function set. Nulling the callback is used as hack-hoc state to indicate
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// that something else has called back the user and will unmap this tag so
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// there's no reason for us to post this.
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if(!tag.cb)
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return;
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auto handler
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{
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std::bind(&resolver::handle_post_error, this, tag.id, std::ref(tag), std::cref(ec))
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};
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// Callback gets a fresh stack off this timeout worker ctx's stack.
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ircd::post(std::move(handler));
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}
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void
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ircd::net::dns::resolver::handle_post_error(const uint16_t id,
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tag &tag,
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const std::system_error &ec)
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{
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// Have to check if the tag is still mapped at this point. It may
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// have been removed if a belated reply came in while this closure
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// was posting. If so, that's good news and we bail on the timeout.
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if(!tags.count(id))
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return;
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log::error
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{
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log, "DNS error id:%u for '%s' :%s",
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id,
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string(tag.hp),
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string(ec)
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};
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assert(tag.cb);
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tag.cb(std::make_exception_ptr(ec), tag.hp, {});
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const auto erased(tags.erase(tag.id));
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assert(erased == 1);
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}
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/// Internal resolver entry interface.
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void
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ircd::net::dns::resolver::operator()(const hostport &hp,
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const opts &opts,
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callback &&callback)
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{
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auto &tag
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{
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set_tag(hp, opts, std::move(callback))
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};
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// Escape trunk
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const unwind::exceptional untag{[this, &tag]
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{
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tags.erase(tag.id);
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}};
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tag.question = make_query(tag.qbuf, tag);
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submit(tag);
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}
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ircd::const_buffer
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ircd::net::dns::resolver::make_query(const mutable_buffer &buf,
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const tag &tag)
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{
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thread_local char hostbuf[rfc1035::NAME_BUF_SIZE * 2];
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string_view hoststr;
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switch(tag.opts.qtype)
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{
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case 0: throw error
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{
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"A query type is required to form a question."
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};
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case 33: // SRV
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{
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hoststr = make_SRV_key(hostbuf, host(tag.hp), tag.opts);
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break;
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}
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default:
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hoststr = host(tag.hp);
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break;
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}
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assert(hoststr);
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assert(tag.opts.qtype);
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const rfc1035::question question
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{
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hoststr, tag.opts.qtype
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};
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return rfc1035::make_query(buf, tag.id, question);
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}
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template<class... A>
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ircd::net::dns::resolver::tag &
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ircd::net::dns::resolver::set_tag(A&&... args)
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{
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while(tags.size() < 65535)
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{
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auto id(ircd::rand::integer(1, 65535));
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auto it{tags.lower_bound(id)};
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if(it != end(tags) && it->first == id)
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continue;
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it = tags.emplace_hint(it,
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std::piecewise_construct,
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std::forward_as_tuple(id),
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std::forward_as_tuple(std::forward<A>(args)...));
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it->second.id = id;
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dock.notify_one();
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return it->second;
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}
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throw panic
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{
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"Too many DNS queries"
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};
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}
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void
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ircd::net::dns::resolver::queue_query(tag &tag)
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{
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assert(sendq.size() <= tags.size());
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sendq.emplace_back(tag.id);
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dock.notify_one();
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}
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void
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ircd::net::dns::resolver::submit(tag &tag)
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{
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assert(ns.is_open());
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const auto rate(milliseconds(send_rate) / server.size());
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const auto elapsed(now<steady_point>() - send_last);
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if(elapsed >= rate || tags.size() < size_t(send_burst))
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send_query(tag);
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else
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queue_query(tag);
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}
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void
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ircd::net::dns::resolver::send_query(tag &tag)
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try
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{
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assert(!server.empty());
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++server_next %= server.size();
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const auto &ep
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{
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server.at(server_next)
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};
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send_query(ep, tag);
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#ifdef RB_DEBUG
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thread_local char buf[128];
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log::debug
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{
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net::log, "dns %s send tag:%u t:%u qtype:%u `%s'",
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string(buf, make_ipport(ep)),
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tag.id,
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tag.tries,
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tag.opts.qtype,
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host(tag.hp),
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};
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#endif
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}
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catch(const std::out_of_range &)
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{
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throw error
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{
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"No DNS servers available for query"
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};
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}
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void
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ircd::net::dns::resolver::send_query(const ip::udp::endpoint &ep,
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tag &tag)
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{
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assert(ns.non_blocking());
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assert(!empty(tag.question));
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const const_buffer &buf{tag.question};
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const auto sent
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{
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ns.send_to(asio::const_buffers_1(buf), ep)
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};
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send_last = now<steady_point>();
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tag.last = send_last;
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tag.server = make_ipport(ep);
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tag.tries++;
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}
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void
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ircd::net::dns::resolver::set_handle()
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{
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auto handler
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{
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std::bind(&resolver::handle, this, ph::_1, ph::_2)
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};
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const asio::mutable_buffers_1 bufs{reply};
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ns.async_receive_from(bufs, reply_from, std::move(handler));
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}
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void
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ircd::net::dns::resolver::handle(const error_code &ec,
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const size_t &bytes)
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noexcept try
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{
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if(!handle_error(ec))
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return;
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const unwind reset{[this]
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{
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set_handle();
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}};
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if(unlikely(bytes < sizeof(rfc1035::header)))
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throw rfc1035::error
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{
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"Got back %zu bytes < rfc1035 %zu byte header",
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bytes,
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sizeof(rfc1035::header)
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};
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char *const reply
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{
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data(this->reply)
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};
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rfc1035::header &header
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{
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*reinterpret_cast<rfc1035::header *>(reply)
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};
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bswap(&header.qdcount);
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bswap(&header.ancount);
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bswap(&header.nscount);
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bswap(&header.arcount);
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const const_buffer body
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{
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reply + sizeof(header), bytes - sizeof(header)
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};
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handle_reply(header, body);
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}
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catch(const std::exception &e)
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{
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throw panic
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{
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"resolver::handle_reply(): %s", e.what()
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};
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}
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void
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ircd::net::dns::resolver::handle_reply(const header &header,
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const const_buffer &body)
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try
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{
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thread_local char addr_strbuf[2][128];
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const auto it{tags.find(header.id)};
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if(it == end(tags))
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throw error
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{
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"DNS reply from %s for unrecognized tag id:%u",
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string(addr_strbuf[0], reply_from),
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header.id
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};
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auto &tag{it->second};
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if(make_ipport(reply_from) != tag.server)
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throw error
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{
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"DNS reply from %s for tag:%u which we sent to %s",
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string(addr_strbuf[0], reply_from),
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header.id,
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string(addr_strbuf[1], tag.server)
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};
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const unwind untag{[this, &it]
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{
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tags.erase(it);
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}};
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log::debug
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{
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net::log, "dns %s recv tag:%u t:%u qtype:%u qd:%u an:%u ns:%u ar:%u",
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string(addr_strbuf[0], make_ipport(reply_from)),
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tag.id,
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tag.tries,
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tag.opts.qtype,
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header.qdcount,
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header.ancount,
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header.nscount,
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header.arcount,
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};
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|
assert(tag.tries > 0);
|
|
tag.last = steady_point::min();
|
|
handle_reply(header, body, tag);
|
|
}
|
|
catch(const std::exception &e)
|
|
{
|
|
log::error
|
|
{
|
|
log, "%s", e.what()
|
|
};
|
|
|
|
return;
|
|
}
|
|
|
|
void
|
|
ircd::net::dns::resolver::handle_reply(const header &header,
|
|
const const_buffer &body,
|
|
tag &tag)
|
|
try
|
|
{
|
|
if(unlikely(header.qr != 1))
|
|
throw rfc1035::error
|
|
{
|
|
"Response header is marked as 'Query' and not 'Response'"
|
|
};
|
|
|
|
if(header.qdcount > MAX_COUNT || header.ancount > MAX_COUNT)
|
|
throw error
|
|
{
|
|
"Response contains too many sections..."
|
|
};
|
|
|
|
const_buffer buffer
|
|
{
|
|
body
|
|
};
|
|
|
|
// Questions are regurgitated back to us so they must be parsed first
|
|
thread_local std::array<rfc1035::question, MAX_COUNT> qd;
|
|
for(size_t i(0); i < header.qdcount; ++i)
|
|
consume(buffer, size(qd.at(i).parse(buffer)));
|
|
|
|
if(!handle_error(header, qd.at(0), tag))
|
|
throw rfc1035::error
|
|
{
|
|
"protocol error #%u :%s", header.rcode, rfc1035::rcode.at(header.rcode)
|
|
};
|
|
|
|
// Answers are parsed into this buffer
|
|
thread_local std::array<rfc1035::answer, MAX_COUNT> an;
|
|
for(size_t i(0); i < header.ancount; ++i)
|
|
consume(buffer, size(an.at(i).parse(buffer)));
|
|
|
|
if(tag.opts.cache_result)
|
|
{
|
|
// We convert all TTL values in the answers to absolute epoch time
|
|
// indicating when they expire. This makes more sense for our caches.
|
|
const auto &now{ircd::time()};
|
|
for(size_t i(0); i < header.ancount; ++i)
|
|
{
|
|
const uint &min_ttl(seconds(cache::min_ttl).count());
|
|
an.at(i).ttl = now + std::max(an.at(i).ttl, min_ttl);
|
|
}
|
|
}
|
|
|
|
// The callback to the user will be passed a vector_view of pointers
|
|
// to this array. The actual record instances will either be located
|
|
// in the cache map or placement-newed to the buffer below.
|
|
thread_local std::array<const rfc1035::record *, MAX_COUNT> record;
|
|
|
|
// This will be where we place the record instances which are dynamically
|
|
// laid out and sized types. 512 bytes is assumed as a soft maximum for
|
|
// each RR instance.
|
|
static const size_t recsz(512);
|
|
thread_local uint8_t recbuf[recsz * MAX_COUNT];
|
|
|
|
size_t i(0);
|
|
uint8_t *pos{recbuf};
|
|
for(; i < header.ancount; ++i) switch(an.at(i).qtype)
|
|
{
|
|
case 1: // A records are inserted into cache
|
|
{
|
|
using type = rfc1035::record::A;
|
|
if(!tag.opts.cache_result)
|
|
{
|
|
if(unlikely(pos + sizeof(type) > recbuf + sizeof(recbuf)))
|
|
break;
|
|
|
|
record.at(i) = new (pos) type(an.at(i));
|
|
pos += sizeof(type);
|
|
continue;
|
|
}
|
|
|
|
record.at(i) = cache::put(qd.at(0), an.at(i));
|
|
continue;
|
|
}
|
|
|
|
case 5:
|
|
{
|
|
using type = rfc1035::record::CNAME;
|
|
if(unlikely(pos + sizeof(type) > recbuf + sizeof(recbuf)))
|
|
break;
|
|
|
|
record.at(i) = new (pos) type(an.at(i));
|
|
pos += sizeof(type);
|
|
continue;
|
|
}
|
|
|
|
case 33:
|
|
{
|
|
using type = rfc1035::record::SRV;
|
|
if(!tag.opts.cache_result)
|
|
{
|
|
if(unlikely(pos + sizeof(type) > recbuf + sizeof(recbuf)))
|
|
break;
|
|
|
|
record.at(i) = new (pos) type(an.at(i));
|
|
pos += sizeof(type);
|
|
continue;
|
|
}
|
|
|
|
record.at(i) = cache::put(qd.at(0), an.at(i));
|
|
continue;
|
|
}
|
|
|
|
default:
|
|
{
|
|
using type = rfc1035::record;
|
|
if(unlikely(pos + sizeof(type) > recbuf + sizeof(recbuf)))
|
|
break;
|
|
|
|
record.at(i) = new (pos) type(an.at(i));
|
|
pos += sizeof(type);
|
|
continue;
|
|
}
|
|
}
|
|
|
|
// Cache no answers here.
|
|
if(!header.ancount && tag.opts.cache_result)
|
|
cache::put_error(qd.at(0), header.rcode);
|
|
|
|
if(tag.cb)
|
|
{
|
|
static const std::exception_ptr no_exception{};
|
|
const vector_view<const rfc1035::record *> records
|
|
{
|
|
record.data(), i
|
|
};
|
|
|
|
tag.cb(no_exception, tag.hp, records);
|
|
}
|
|
}
|
|
catch(const std::exception &e)
|
|
{
|
|
// There's no need to flash red to the log for NXDOMAIN which is
|
|
// common in this system when probing SRV.
|
|
if(unlikely(header.rcode != 3))
|
|
log::error
|
|
{
|
|
log, "resolver tag:%u: %s",
|
|
tag.id,
|
|
e.what()
|
|
};
|
|
|
|
if(tag.cb)
|
|
{
|
|
assert(header.rcode != 3 || tag.opts.nxdomain_exceptions);
|
|
tag.cb(std::current_exception(), tag.hp, {});
|
|
}
|
|
}
|
|
|
|
bool
|
|
ircd::net::dns::resolver::handle_error(const header &header,
|
|
const rfc1035::question &question,
|
|
tag &tag)
|
|
{
|
|
switch(header.rcode)
|
|
{
|
|
case 0: // NoError; continue
|
|
return true;
|
|
|
|
case 3: // NXDomain; exception
|
|
{
|
|
if(!tag.opts.cache_result)
|
|
return false;
|
|
|
|
const auto *record
|
|
{
|
|
cache::put_error(question, header.rcode)
|
|
};
|
|
|
|
// When the user doesn't want an eptr for nxdomain we just make
|
|
// their callback here and then null the cb pointer so it's not
|
|
// called again. It is done here because we have a reference to
|
|
// the cached error record readily accessible.
|
|
if(!tag.opts.nxdomain_exceptions && tag.cb)
|
|
{
|
|
assert(record);
|
|
tag.cb({}, tag.hp, vector_view<const rfc1035::record *>(&record, 1));
|
|
tag.cb = {};
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
default: // Unhandled error; exception
|
|
return false;
|
|
}
|
|
}
|
|
|
|
bool
|
|
ircd::net::dns::resolver::handle_error(const error_code &ec)
|
|
const
|
|
{
|
|
using std::errc;
|
|
|
|
if(system_category(ec)) switch(ec.value())
|
|
{
|
|
case 0:
|
|
return true;
|
|
|
|
case int(errc::operation_canceled):
|
|
return false;
|
|
|
|
default:
|
|
break;
|
|
}
|
|
|
|
throw std::system_error{ec};
|
|
}
|
|
|
|
void
|
|
ircd::net::dns::resolver::set_servers()
|
|
{
|
|
const std::string &list(resolver::servers);
|
|
set_servers(list);
|
|
}
|
|
|
|
void
|
|
ircd::net::dns::resolver::set_servers(const string_view &list)
|
|
{
|
|
server.clear();
|
|
server_next = 0;
|
|
tokens(list, ';', [this]
|
|
(const hostport &hp)
|
|
{
|
|
const auto &port
|
|
{
|
|
net::port(hp) != canon_port? net::port(hp) : uint16_t(53)
|
|
};
|
|
|
|
const ipport ipp
|
|
{
|
|
host(hp), port
|
|
};
|
|
|
|
add_server(ipp);
|
|
});
|
|
}
|
|
|
|
void
|
|
ircd::net::dns::resolver::add_server(const ipport &ipp)
|
|
{
|
|
server.emplace_back(make_endpoint_udp(ipp));
|
|
|
|
log::debug
|
|
{
|
|
log, "Adding [%s] as DNS server #%zu",
|
|
string(ipp),
|
|
server.size()
|
|
};
|
|
}
|