379 lines
8.7 KiB
C++
379 lines
8.7 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 "net_dns.h"
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namespace ircd::net::dns
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{
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template<class T> static rfc1035::record *new_record(mutable_buffer &, const rfc1035::answer &);
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static void handle_resolved(std::exception_ptr, const tag &, const answers &);
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static void handle_resolve_A_ipport(const hostport &, const json::object &rr, opts, uint16_t, callback_ipport);
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static void handle_resolve_SRV_ipport(const hostport &, const json::object &rr, opts, callback_ipport);
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static void handle_resolve_one(const hostport &, const json::array &rr, callback_one);
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static void fini();
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static void init();
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}
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ircd::mapi::header
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IRCD_MODULE
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{
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"Domain Name System Client, Cache & Components",
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ircd::net::dns::init,
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ircd::net::dns::fini,
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};
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void
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ircd::net::dns::init()
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{
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cache::init();
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resolver_init(handle_resolved);
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}
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void
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ircd::net::dns::fini()
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{
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cache::fini();
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resolver_fini();
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}
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void
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IRCD_MODULE_EXPORT
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ircd::net::dns::resolve(const hostport &hp,
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const opts &opts_,
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callback_ipport callback)
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{
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if(unlikely(!port(hp) && !hp.service))
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throw error
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{
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"Port or service is required for this query"
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};
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dns::opts opts(opts_);
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opts.qtype = opts_.qtype?: 33; // default to SRV
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if(opts.qtype == 33)
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{
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opts.nxdomain_exceptions = false;
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net::dns::callback_one handler
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{
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std::bind(&handle_resolve_SRV_ipport, ph::_1, ph::_2, opts, std::move(callback))
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};
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resolve(hp, opts, std::move(handler));
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}
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else if(opts.qtype == 1 || opts.qtype == 28)
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{
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net::dns::callback_one handler
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{
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std::bind(&handle_resolve_A_ipport, ph::_1, ph::_2, opts, port(hp), std::move(callback))
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};
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resolve(hp, opts, std::move(handler));
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}
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else throw error
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{
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"Query type:%u not valid for ipport result callback.", opts.qtype
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};
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}
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void
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IRCD_MODULE_EXPORT
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ircd::net::dns::resolve(const hostport &hp,
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const opts &opts,
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callback_one callback)
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{
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if(unlikely(!opts.qtype))
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throw error
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{
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"A query type is required; not specified; cannot be deduced here."
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};
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dns::callback handler
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{
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std::bind(&handle_resolve_one, ph::_1, ph::_2, std::move(callback))
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};
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resolve(hp, opts, std::move(handler));
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}
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void
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IRCD_MODULE_EXPORT
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ircd::net::dns::resolve(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(!opts.qtype))
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throw error
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{
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"A query type is required; not specified; cannot be deduced here."
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};
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// Try to satisfy from the cache first. This requires a ctx.
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if(likely(ctx::current && opts.cache_check))
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if(cache::get(hp, opts, cb))
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return;
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// Remote query will be made; register this callback as waiting for reply
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assert(cb);
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cache::waiting.emplace_back(hp, opts, std::move(cb));
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// Check if there is already someone else waiting on the same query
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const auto count
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{
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std::count_if(begin(cache::waiting), end(cache::waiting), []
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(const auto &a)
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{
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return a == cache::waiting.back();
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})
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};
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// When nobody else is already waiting on this query we have to submit it.
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assert(count >= 1);
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if(count == 1)
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resolver_call(hp, opts);
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}
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void
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ircd::net::dns::handle_resolve_one(const hostport &hp,
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const json::array &rrs,
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callback_one callback)
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{
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const json::object &rr
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{
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random_choice(rrs)
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};
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callback(hp, rr);
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}
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void
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ircd::net::dns::handle_resolve_SRV_ipport(const hostport &hp,
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const json::object &rr,
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opts opts,
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callback_ipport callback)
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{
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const json::string &error
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{
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rr.get("error")
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};
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const hostport &target
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{
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rr.has("tgt")?
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rstrip(unquote(rr.at("tgt")), '.'):
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host(hp),
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rr.has("port")?
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rr.get<uint16_t>("port"):
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!error?
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port(hp):
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uint16_t(0)
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};
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if(error)
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{
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static const ipport empty;
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const auto eptr
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{
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make_exception_ptr<rfc1035::error>(exception::hide_name, "%s", error)
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};
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return callback(eptr, target, empty);
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}
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opts.qtype = 1;
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opts.nxdomain_exceptions = true;
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net::dns::callback_one handler
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{
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std::bind(&handle_resolve_A_ipport, ph::_1, ph::_2, opts, port(target), std::move(callback))
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};
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resolve(target, opts, std::move(handler));
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}
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void
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ircd::net::dns::handle_resolve_A_ipport(const hostport &hp,
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const json::object &rr,
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const opts opts,
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const uint16_t port,
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const callback_ipport callback)
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{
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const json::string &error
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{
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rr.get("error")
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};
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const json::string &ip
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{
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opts.qtype == 28?
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rr.get("ip", ":::0"_sv):
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rr.get("ip", "0.0.0.0"_sv)
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};
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const ipport &ipport
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{
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ip, port
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};
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const hostport &target
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{
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host(hp), port
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};
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const auto eptr
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{
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!empty(error)?
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make_exception_ptr<rfc1035::error>(exception::hide_name, "%s", error):
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!ipport?
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make_exception_ptr<net::error>("Host has no A record."):
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std::exception_ptr{}
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};
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callback(eptr, target, ipport);
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}
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/// Called back from the dns::resolver with a vector of answers to the
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/// question (we get the whole tag here).
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///
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/// This is being invoked on the dns::resolver's receiver context stack
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/// under lock preventing any other activity with the resolver.
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///
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/// We process these results and insert them into our cache. The cache
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/// insertion involves sending a message to the DNS room. Matrix hooks
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/// on that room will catch this message for the user(s) which initiated
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/// this query; we don't callback or deal with said users here.
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///
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void
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ircd::net::dns::handle_resolved(std::exception_ptr eptr,
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const tag &tag,
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const answers &an)
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try
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{
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static const size_t recsz(1024);
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thread_local char recbuf[recsz * MAX_COUNT];
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thread_local std::array<const rfc1035::record *, MAX_COUNT> record;
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size_t i(0);
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mutable_buffer buf{recbuf};
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for(; i < an.size(); ++i) switch(an.at(i).qtype)
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{
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case 1:
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record.at(i) = new_record<rfc1035::record::A>(buf, an.at(i));
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continue;
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case 5:
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record.at(i) = new_record<rfc1035::record::CNAME>(buf, an.at(i));
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continue;
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case 28:
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record.at(i) = new_record<rfc1035::record::AAAA>(buf, an.at(i));
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continue;
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case 33:
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record.at(i) = new_record<rfc1035::record::SRV>(buf, an.at(i));
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continue;
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default:
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record.at(i) = new_record<rfc1035::record>(buf, an.at(i));
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continue;
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}
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// Sort the records by type so we can create smaller vectors to send to the
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// cache. nulls from running out of space should be pushed to the back.
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std::sort(begin(record), begin(record) + an.size(), []
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(const auto *const &a, const auto *const &b)
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{
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if(!a)
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return false;
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if(!b)
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return true;
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return a->type < b->type;
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});
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//TODO: don't send cache ephemeral rcodes
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// Bail on error here; send the cache the message
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if(eptr)
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{
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cache::put(tag.hp, tag.opts, tag.rcode, what(eptr));
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return;
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}
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// Branch on no records with no error
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if(!i)
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{
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static const records empty;
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cache::put(tag.hp, tag.opts, empty);
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return;
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}
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// Iterate the record vector which was sorted by type;
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// send the cache an individual view of each type since
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// the cache is organized by record type.
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size_t s(0), e(0);
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auto last(record.at(e)->type);
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for(++e; e <= i; ++e)
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{
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if(e < i && record.at(e)->type == last)
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continue;
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const vector_view<const rfc1035::record *> records
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{
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record.data() + s, record.data() + e
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};
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assert(!empty(records));
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cache::put(tag.hp, tag.opts, records);
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s = e;
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if(e < i)
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last = record.at(e)->type;
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}
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// We have to send something to the cache with the same type
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// as the query, otherwise our user will never get a response
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// to what they're waiting for.
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bool has_tag_qtype{false};
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for(size_t i(0); i < an.size() && !has_tag_qtype; ++i)
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has_tag_qtype = an.at(i).qtype == tag.opts.qtype;
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if(!has_tag_qtype)
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{
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static const records empty;
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cache::put(tag.hp, tag.opts, empty);
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}
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}
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catch(const std::exception &e)
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{
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log::error
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{
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log, "handle resolved: tag[%u] :%s",
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tag.id,
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e.what()
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};
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throw;
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}
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template<class type>
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ircd::rfc1035::record *
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ircd::net::dns::new_record(mutable_buffer &buf,
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const rfc1035::answer &answer)
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{
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if(unlikely(sizeof(type) > size(buf)))
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return nullptr;
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void *const pos(data(buf));
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consume(buf, sizeof(type));
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return new (pos) type(answer);
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}
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