From 59ad4731ae891ec2295af392be240d147f730d8a Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Tue, 10 Mar 2020 21:59:15 -0700
Subject: [PATCH] modules/m_relation: Add hook to discover and fetch events
from m_relates_to.
---
matrix/matrix.cc | 1 +
modules/Makefile.am | 2 +
modules/m_relation.cc | 147 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 150 insertions(+)
create mode 100644 modules/m_relation.cc
diff --git a/matrix/matrix.cc b/matrix/matrix.cc
index 3f457879d..af54a28d3 100644
--- a/matrix/matrix.cc
+++ b/matrix/matrix.cc
@@ -71,6 +71,7 @@ ircd::m::matrix::module_names
"m_presence",
"m_profile",
"m_receipt",
+ "m_relation",
"m_room_aliases",
"m_room_canonical_alias",
"m_room_create",
diff --git a/modules/Makefile.am b/modules/Makefile.am
index d666f7b73..2fc63e993 100644
--- a/modules/Makefile.am
+++ b/modules/Makefile.am
@@ -101,6 +101,7 @@ m_noop_la_SOURCES = m_noop.cc
m_presence_la_SOURCES = m_presence.cc
m_profile_la_SOURCES = m_profile.cc
m_receipt_la_SOURCES = m_receipt.cc
+m_relation_la_SOURCES = m_relation.cc
m_room_aliases_la_SOURCES = m_room_aliases.cc
m_room_canonical_alias_la_SOURCES = m_room_canonical_alias.cc
m_room_create_la_SOURCES = m_room_create.cc
@@ -130,6 +131,7 @@ m_module_LTLIBRARIES = \
m_presence.la \
m_profile.la \
m_receipt.la \
+ m_relation.la \
m_room_aliases.la \
m_room_canonical_alias.la \
m_room_create.la \
diff --git a/modules/m_relation.cc b/modules/m_relation.cc
new file mode 100644
index 000000000..103942d8a
--- /dev/null
+++ b/modules/m_relation.cc
@@ -0,0 +1,147 @@
+// The Construct
+//
+// Copyright (C) The Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2020 Jason Volk <jason@zemos.net>
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice is present in all copies. The
+// full license for this software is available in the LICENSE file.
+
+namespace ircd::m::relation
+{
+ static void handle_fetch(const event &, vm::eval &);
+ extern hookfn<vm::eval &> fetch_hook;
+ extern conf::item<seconds> fetch_timeout;
+ extern conf::item<bool> fetch_enable;
+}
+
+ircd::mapi::header
+IRCD_MODULE
+{
+ "Matrix relations"
+};
+
+decltype(ircd::m::relation::fetch_enable)
+ircd::m::relation::fetch_enable
+{
+ { "name", "ircd.m.relation.fetch.enable" },
+ { "default", true },
+};
+
+decltype(ircd::m::relation::fetch_timeout)
+ircd::m::relation::fetch_timeout
+{
+ { "name", "ircd.m.relation.fetch.timeout" },
+ { "default", 5L },
+};
+
+decltype(ircd::m::relation::fetch_hook)
+ircd::m::relation::fetch_hook
+{
+ handle_fetch,
+ {
+ { "_site", "vm.fetch" },
+ }
+};
+
+void
+ircd::m::relation::handle_fetch(const event &event,
+ vm::eval &eval)
+try
+{
+ assert(eval.opts);
+ const auto &opts{*eval.opts};
+ if(!opts.fetch_prev)
+ return;
+
+ if(!fetch_enable)
+ return;
+
+ if(my(event))
+ return;
+
+ // event must be in a room for now; we won't have context until dht
+ if(!json::get<"room_id"_>(event))
+ return;
+
+ const auto &content
+ {
+ json::get<"content"_>(event)
+ };
+
+ const json::object &m_relates_to
+ {
+ content["m.relates_to"]
+ };
+
+ if(!m_relates_to || json::type(m_relates_to) != json::OBJECT)
+ return;
+
+ const event::id &event_id
+ {
+ m_relates_to["event_id"]
+ };
+
+ // If the relates_to is a prev_event then the vm::fetch unit will perform
+ // the fetch so this will just be redundant and we can bail.
+ const event::prev prev{event};
+ if(prev.prev_events_has(event_id))
+ return;
+
+ if(likely(m::exists(event_id)))
+ return;
+
+ log::dwarning
+ {
+ log, "%s in %s by %s relates to missing %s; fetching...",
+ string_view(event.event_id),
+ string_view(at<"room_id"_>(event)),
+ string_view(at<"sender"_>(event)),
+ string_view(event_id),
+ };
+
+ m::fetch::opts fetch_opts;
+ fetch_opts.op = m::fetch::op::event;
+ fetch_opts.room_id = at<"room_id"_>(event);
+ fetch_opts.event_id = event_id;
+ auto request
+ {
+ m::fetch::start(fetch_opts)
+ };
+
+ const auto response
+ {
+ request.get(seconds(fetch_timeout))
+ };
+
+ const m::event result
+ {
+ json::object
+ {
+ response
+ }
+ };
+
+ auto eval_opts(opts);
+ eval_opts.fetch_prev = false;
+ eval_opts.fetch_state = false;
+ vm::eval
+ {
+ result, eval_opts
+ };
+}
+catch(const ctx::interrupted &)
+{
+ throw;
+}
+catch(const std::exception &e)
+{
+ log::derror
+ {
+ log, "Failed to fetch relation for %s in %s :%s",
+ string_view(event.event_id),
+ string_view(json::get<"room_id"_>(event)),
+ e.what(),
+ };
+}