mirror of
https://github.com/matrix-construct/construct
synced 2024-12-25 06:53:58 +01:00
432 lines
9.2 KiB
C++
432 lines
9.2 KiB
C++
// The Construct
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//
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// Copyright (C) The Construct Developers, Authors & Contributors
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// Copyright (C) 2016-2020 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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namespace ircd::m::fed::well_known
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{
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static std::tuple<ircd::http::code, ircd::string_view, ircd::string_view>
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fetch(const mutable_buffer &,
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const net::hostport &,
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const string_view &url);
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extern log::log log;
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}
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decltype(ircd::m::fed::well_known::log)
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ircd::m::fed::well_known::log
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{
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"m.well-known"
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};
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decltype(ircd::m::fed::well_known::cache_default)
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ircd::m::fed::well_known::cache_default
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{
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{ "name", "ircd.m.fed.well-known.cache.default" },
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{ "default", 24 * 60 * 60L },
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};
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decltype(ircd::m::fed::well_known::cache_error)
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ircd::m::fed::well_known::cache_error
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{
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{ "name", "ircd.m.fed.well-known.cache.error" },
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{ "default", 36 * 60 * 60L },
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};
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///NOTE: not yet used until HTTP cache headers in response are respected.
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decltype(ircd::m::fed::well_known::cache_max)
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ircd::m::fed::well_known::cache_max
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{
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{ "name", "ircd.m.fed.well-known.cache.max" },
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{ "default", 48 * 60 * 60L },
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};
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decltype(ircd::m::fed::well_known::fetch_timeout)
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ircd::m::fed::well_known::fetch_timeout
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{
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{ "name", "ircd.m.fed.well-known.fetch.timeout" },
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{ "default", 15L },
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};
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decltype(ircd::m::fed::well_known::fetch_redirects)
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ircd::m::fed::well_known::fetch_redirects
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{
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{ "name", "ircd.m.fed.well-known.fetch.redirects" },
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{ "default", 2L },
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};
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ircd::string_view
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ircd::m::fed::well_known::get(const mutable_buffer &buf,
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const string_view &origin)
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try
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{
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static const string_view type
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{
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"well-known.matrix.server"
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};
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const m::room::id::buf room_id
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{
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"dns", m::my_host()
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};
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const m::room room
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{
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room_id
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};
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const m::event::idx event_idx
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{
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room.get(std::nothrow, type, origin)
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};
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const milliseconds origin_server_ts
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{
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m::get<time_t>(std::nothrow, event_idx, "origin_server_ts", time_t(0))
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};
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const json::object content
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{
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origin_server_ts > 0ms?
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m::get(std::nothrow, event_idx, "content", buf):
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const_buffer{}
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};
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const seconds ttl
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{
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content.get<time_t>("ttl", time_t(86400))
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};
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const string_view cached
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{
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data(buf), move(buf, json::string(content["m.server"]))
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};
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const system_point expires
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{
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origin_server_ts + ttl
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};
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const bool expired
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{
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ircd::now<system_point>() > expires
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};
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const bool valid
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{
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!empty(cached)
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};
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// Crucial value that will provide us with a return string for this
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// function in any case. This is obtained by either using the value
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// found in cache or making a network query for a new value. expired=true
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// when a network query needs to be made, otherwise we can return the
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// cached value. If the network query fails, this value is still defaulted
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// as the origin string to return and we'll also cache that too.
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const string_view delegated
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{
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expired || !valid?
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fetch(buf + size(cached), origin):
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cached
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};
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// Branch on valid cache hit to return result.
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if(valid && !expired)
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{
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char tmbuf[48];
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log::debug
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{
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log, "%s found in cache delegated to %s event_idx:%u expires %s",
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origin,
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cached,
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event_idx,
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timef(tmbuf, expires, localtime),
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};
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return delegated;
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}
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// Conditions for valid expired cache hit w/ failure to reacquire.
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const bool fallback
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{
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valid
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&& expired
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&& cached != delegated
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&& origin == delegated
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&& now<system_point>() < expires + seconds(cache_max)
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};
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if(fallback)
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{
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char tmbuf[48];
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log::debug
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{
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log, "%s found in cache delegated to %s event_idx:%u expired %s",
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origin,
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cached,
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event_idx,
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timef(tmbuf, expires, localtime),
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};
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return cached;
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}
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// Any time the well-known result is the same as the origin (that
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// includes legitimate errors where fetch_well_known() returns the
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// origin to default) we consider that an error and use the error
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// TTL value. Sorry, no exponential backoff implemented yet.
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const auto cache_ttl
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{
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origin == delegated?
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seconds(cache_error).count():
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seconds(cache_default).count()
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};
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// Write our record to the cache room; note that this doesn't really
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// match the format of other DNS records in this room since it's a bit
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// simpler, but we don't share the ircd.dns.rr type prefix anyway.
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const auto cache_id
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{
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m::send(room, m::me(), type, origin, json::members
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{
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{ "ttl", cache_ttl },
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{ "m.server", delegated },
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})
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};
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log::debug
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{
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log, "%s caching delegation to %s to cache in %s",
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origin,
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delegated,
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string_view{cache_id},
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};
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return delegated;
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}
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catch(const ctx::interrupted &)
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{
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throw;
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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, "%s :%s",
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origin,
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e.what(),
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};
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return string_view
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{
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data(buf), move(buf, origin)
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};
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}
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ircd::string_view
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ircd::m::fed::well_known::fetch(const mutable_buffer &user_buf,
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const string_view &origin)
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try
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{
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static const string_view path
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{
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"/.well-known/matrix/server"
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};
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// If the supplied buffer isn't large enough to make the full
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// HTTP request, allocate one that is.
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const unique_mutable_buffer req_buf
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{
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size(user_buf) < 8_KiB? 8_KiB: 0UL
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};
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const mutable_buffer buf
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{
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req_buf? req_buf: user_buf
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};
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rfc3986::uri uri;
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uri.remote = origin;
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uri.path = path;
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json::object response;
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unique_mutable_buffer carry;
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for(size_t i(0); i < fetch_redirects; ++i)
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{
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const auto &[code, location, content]
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{
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fetch(buf, uri.remote, uri.path)
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};
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// Successful error; bail
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if(code >= 400)
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return string_view
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{
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data(user_buf), move(user_buf, origin)
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};
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// Successful result; response content handled after loop.
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if(code < 300)
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{
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response = content;
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break;
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}
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// Indirection code, but no location response header
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if(!location)
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return string_view
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{
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data(user_buf), move(user_buf, origin)
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};
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// Redirection; carry over the new target by copying it because it's
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// in the buffer which we'll be overwriting for the new request.
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carry = unique_mutable_buffer{location};
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uri = string_view{carry};
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// Indirection code, bad location header.
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if(!uri.path || !uri.remote)
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return string_view
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{
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data(user_buf), move(user_buf, origin)
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};
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}
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const json::string &m_server
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{
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response["m.server"]
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};
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if(!m_server)
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return string_view
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{
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data(user_buf), move(user_buf, origin)
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};
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// This construction validates we didn't get a junk string
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volatile const net::hostport ret
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{
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m_server
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};
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log::debug
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{
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log, "%s query to %s found delegation to %s",
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origin,
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uri.remote,
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m_server,
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};
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// Move the returned string to the front of the buffer; this overwrites
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// any other incoming content to focus on just the unquoted string.
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return string_view
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{
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data(user_buf), move(user_buf, m_server)
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};
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}
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catch(const ctx::interrupted &)
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{
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throw;
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}
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catch(const std::exception &e)
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{
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log::derror
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{
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log, "%s in network query :%s",
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origin,
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e.what(),
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};
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return string_view
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{
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data(user_buf), move(user_buf, origin)
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};
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}
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/// Return a tuple of the HTTP code, any Location header, and the response
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/// content. These values are unconditional if this function doesn't throw,
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/// but if there's no Location header and/or content then those will be empty
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/// string_view's. This function is intended to be run in a loop by the caller
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/// to chase redirection. No HTTP codes will throw from here; server and
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/// network errors (and others) will.
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std::tuple<ircd::http::code, ircd::string_view, ircd::string_view>
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ircd::m::fed::well_known::fetch(const mutable_buffer &buf,
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const net::hostport &remote,
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const string_view &url)
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{
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// Hard target https service; do not inherit any matrix service from remote.
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const net::hostport target
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{
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host(remote), "https", port(remote)
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};
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window_buffer wb
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{
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buf
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};
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const http::header headers[]
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{
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{ "User-Agent", info::user_agent },
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};
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http::request
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{
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wb, host(target), "GET", url, 0, {}, headers
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};
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const const_buffer out_head
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{
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wb.completed()
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};
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// Remaining space in buffer is used for received head; note that below
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// we specify this same buffer for in.content, but that's a trick
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// recognized by ircd::server to place received content directly after
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// head in this buffer without any additional dynamic allocation.
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const mutable_buffer in_head
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{
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buf + size(out_head)
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};
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server::request::opts opts;
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opts.http_exceptions = false; // 3xx/4xx/5xx response won't throw.
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server::request request
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{
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target,
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{ out_head },
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{ in_head, in_head },
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&opts
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};
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const auto code
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{
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request.get(seconds(fetch_timeout))
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};
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thread_local char rembuf[rfc3986::DOMAIN_BUFSIZE * 2];
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log::debug
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{
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log, "fetch from %s %s :%u %s",
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string(rembuf, target),
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url,
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uint(code),
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http::status(code)
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};
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const http::response::head head
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{
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request.in.gethead(request)
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};
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return
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{
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code,
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head.location,
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request.in.content,
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};
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}
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