121 lines
4.0 KiB
C++
121 lines
4.0 KiB
C++
/*
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* nghttp2 - HTTP/2 C Library
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*
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* Copyright (c) 2016 Tatsuhiro Tsujikawa
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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#ifndef SHRPX_DNS_TRACKER_H
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#define SHRPX_DNS_TRACKER_H
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#include "shrpx.h"
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#include <map>
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#include "shrpx_dual_dns_resolver.h"
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using namespace nghttp2;
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namespace shrpx {
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struct DNSQuery {
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DNSQuery(StringRef host, CompleteCb cb)
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: host(std::move(host)),
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cb(std::move(cb)),
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dlnext(nullptr),
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dlprev(nullptr),
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status(DNSResolverStatus::IDLE),
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in_qlist(false) {}
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// Host name we lookup for.
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StringRef host;
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// Callback function called when name lookup finished. This
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// callback is not called if name lookup finishes within
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// DNSTracker::resolve().
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CompleteCb cb;
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DNSQuery *dlnext, *dlprev;
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DNSResolverStatus status;
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// true if this object is in linked list ResolverEntry::qlist.
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bool in_qlist;
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};
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struct ResolverEntry {
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// Host name this entry lookups for.
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ImmutableString host;
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// DNS resolver. Only non-nullptr if status is
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// DNSResolverStatus::RUNNING.
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std::unique_ptr<DualDNSResolver> resolv;
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// DNSQuery interested in this name lookup result. The result is
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// notified to them all.
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DList<DNSQuery> qlist;
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// Use the same enum with DNSResolverStatus
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DNSResolverStatus status;
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// result and its expiry time
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Address result;
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// time point when cached result expires.
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ev_tstamp expiry;
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};
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class DNSTracker {
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public:
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DNSTracker(struct ev_loop *loop, int family);
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~DNSTracker();
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// Lookups host name described in |dnsq|. If name lookup finishes
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// within this function (either it came from /etc/hosts, host name
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// is numeric, lookup result is cached, etc), it returns
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// DNSResolverStatus::OK or DNSResolverStatus::ERROR. If lookup is
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// successful, DNSResolverStatus::OK is returned, and |result| is
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// filled. If lookup failed, DNSResolverStatus::ERROR is returned.
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// If name lookup is being done background, it returns
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// DNSResolverStatus::RUNNING. Its completion is notified by
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// calling dnsq->cb.
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DNSResolverStatus resolve(Address *result, DNSQuery *dnsq);
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// Cancels name lookup requested by |dnsq|.
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void cancel(DNSQuery *dnsq);
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// Removes expired entries from ents_.
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void gc();
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// Starts GC timer.
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void start_gc_timer();
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private:
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ResolverEntry make_entry(std::unique_ptr<DualDNSResolver> resolv,
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ImmutableString host, DNSResolverStatus status,
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const Address *result);
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void update_entry(ResolverEntry &ent, std::unique_ptr<DualDNSResolver> resolv,
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DNSResolverStatus status, const Address *result);
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void add_to_qlist(ResolverEntry &ent, DNSQuery *dnsq);
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std::map<StringRef, ResolverEntry> ents_;
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// Periodically iterates ents_, and removes expired entries to avoid
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// excessive use of memory. Since only backend API can potentially
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// increase memory consumption, interval could be very long.
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ev_timer gc_timer_;
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struct ev_loop *loop_;
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// IP version preference.
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int family_;
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};
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} // namespace shrpx
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#endif // SHRPX_DNS_TRACKER_H
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