mirror of
https://github.com/matrix-construct/construct
synced 2024-06-29 07:18:20 +02:00
282 lines
6.7 KiB
C++
282 lines
6.7 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 "s_dns.h"
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decltype(ircd::net::dns::cache::clear_nxdomain)
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ircd::net::dns::cache::clear_nxdomain
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{
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{ "name", "ircd.net.dns.cache.clear_nxdomain" },
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{ "default", 43200L },
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};
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decltype(ircd::net::dns::cache::min_ttl)
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ircd::net::dns::cache::min_ttl
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{
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{ "name", "ircd.net.dns.cache.min_ttl" },
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{ "default", 900L },
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};
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decltype(ircd::net::dns::cache::cache_A)
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ircd::net::dns::cache::cache_A;
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decltype(ircd::net::dns::cache::cache_SRV)
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ircd::net::dns::cache::cache_SRV;
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bool
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ircd::net::dns::cache::_for_each(const uint16_t &type,
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const closure &closure)
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{
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switch(type)
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{
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case 1: // A
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return _for_each_(cache_A, closure);
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case 33: // SRV
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return _for_each_(cache_SRV, closure);
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default:
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return true;
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}
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}
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/// This function has an opportunity to respond from the DNS cache. If it
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/// returns true, that indicates it responded by calling back the user and
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/// nothing further should be done for them. If it returns false, that
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/// indicates it did not respond and to proceed normally. The response can
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/// be of a cached successful result, or a cached error. Both will return
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/// true.
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bool
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ircd::net::dns::cache::_get(const hostport &hp,
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const opts &opts,
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const callback &cb)
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{
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// It's no use putting the result record array on the stack in case this
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// function is either called from an ircd::ctx or calls back an ircd::ctx.
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// If the ctx yields the records can still be evicted from the cache.
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// It's better to just force the user to conform here rather than adding
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// ref counting and other pornographic complications to this cache.
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const ctx::critical_assertion ca;
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thread_local std::array<const rfc1035::record *, MAX_COUNT> record;
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std::exception_ptr eptr;
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size_t count{0};
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if(opts.qtype == 33) // deduced SRV query
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{
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assert(!empty(host(hp)));
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thread_local char srvbuf[512];
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const string_view srvhost
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{
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make_SRV_key(srvbuf, hp, opts)
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};
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auto &map{cache_SRV};
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const auto pit{map.equal_range(srvhost)};
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if(pit.first == pit.second)
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return false;
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const auto &now{ircd::time()};
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for(auto it(pit.first); it != pit.second; )
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{
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const auto &rr{it->second};
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// Cached entry is too old, ignore and erase
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if(rr.ttl < now)
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{
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it = map.erase(it);
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continue;
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}
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// Cached entry is a cached error, we set the eptr, but also
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// include the record and increment the count like normal.
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if((!rr.tgt || !rr.port) && opts.nxdomain_exceptions && !eptr)
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{
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//TODO: we don't cache what the error was, assuming it's
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//TODO: NXDomain can be incorrect and in bad ways downstream...
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static const auto rcode{3}; //NXDomain
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eptr = std::make_exception_ptr(rfc1035::error
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{
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"protocol error #%u (cached) :%s", rcode, rfc1035::rcode.at(rcode)
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});
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}
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if(count < record.size())
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record.at(count++) = &rr;
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++it;
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}
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}
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else if(opts.qtype == 1)
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{
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auto &map{cache_A};
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const auto &key{rstrip(host(hp), '.')};
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if(unlikely(empty(key)))
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return false;
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const auto pit{map.equal_range(key)};
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if(pit.first == pit.second)
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return false;
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const auto &now{ircd::time()};
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for(auto it(pit.first); it != pit.second; )
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{
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const auto &rr{it->second};
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// Cached entry is too old, ignore and erase
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if(rr.ttl < now)
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{
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it = map.erase(it);
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continue;
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}
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// Cached entry is a cached error, we set the eptr, but also
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// include the record and increment the count like normal.
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if(!rr.ip4 && !eptr)
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{
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//TODO: we don't cache what the error was, assuming it's
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//TODO: NXDomain can be incorrect and in bad ways downstream...
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static const auto rcode{3}; //NXDomain
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eptr = std::make_exception_ptr(rfc1035::error
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{
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"protocol error #%u (cached) :%s", rcode, rfc1035::rcode.at(rcode)
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});
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}
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if(count < record.size())
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record.at(count++) = &rr;
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++it;
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}
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}
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assert(count || !eptr); // no error if no cache response
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assert(!eptr || count == 1); // if error, should only be one entry.
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if(count)
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cb(std::move(eptr), hp, vector_view<const rfc1035::record *>(record.data(), count));
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return count;
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}
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ircd::rfc1035::record *
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ircd::net::dns::cache::_put(const rfc1035::question &question,
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const rfc1035::answer &answer)
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{
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const auto &host
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{
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rstrip(question.name, '.')
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};
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assert(!empty(host));
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switch(answer.qtype)
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{
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case 1: // A
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return _cache_answer(cache_A, host, answer);
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case 33: // SRV
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return _cache_answer(cache_SRV, host, answer);
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default:
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return nullptr;
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}
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}
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ircd::rfc1035::record *
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ircd::net::dns::cache::_put_error(const rfc1035::question &question,
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const uint &code)
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{
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const auto &host
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{
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rstrip(question.name, '.')
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};
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assert(!empty(host));
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switch(question.qtype)
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{
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case 1: // A
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return _cache_error<rfc1035::record::A>(cache_A, host);
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case 33: // SRV
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return _cache_error<rfc1035::record::SRV>(cache_SRV, host);
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default:
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return nullptr;
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}
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}
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template<class Map>
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ircd::rfc1035::record *
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ircd::net::dns::cache::_cache_answer(Map &map,
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const string_view &host,
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const rfc1035::answer &answer)
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{
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auto pit
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{
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map.equal_range(host)
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};
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auto it(pit.first);
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while(it != pit.second)
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{
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const auto &rr{it->second};
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if(rr == answer)
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it = map.erase(it);
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else
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++it;
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}
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const auto &iit
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{
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map.emplace_hint(it, host, answer)
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};
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return &iit->second;
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}
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template<class T,
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class Map>
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ircd::rfc1035::record *
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ircd::net::dns::cache::_cache_error(Map &map,
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const string_view &host)
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{
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auto pit
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{
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map.equal_range(host)
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};
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auto it
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{
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pit.first != pit.second?
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map.erase(pit.first, pit.second):
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pit.first
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};
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T record;
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record.ttl = ircd::time() + seconds(dns::cache::clear_nxdomain).count(); //TODO: code
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it = map.emplace_hint(it, host, record);
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return &it->second;
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}
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template<class Map>
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bool
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ircd::net::dns::cache::_for_each_(Map &map,
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const closure &closure)
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{
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for(const auto &pair : map)
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{
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const auto &host(pair.first);
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const auto &record(pair.second);
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if(!closure(host, record))
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return false;
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}
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return true;
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}
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