From 39eb015565d2fe63b4f74bd5c7febd1c56376dd2 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Thu, 25 Oct 2018 16:50:25 -0700
Subject: [PATCH] ircd::m::room: Add join_rule query convenience suite.

---
 include/ircd/m/room.h |  4 ++-
 ircd/m/room.cc        | 64 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 67 insertions(+), 1 deletion(-)

diff --git a/include/ircd/m/room.h b/include/ircd/m/room.h
index 19ac13ca2..60d7170a3 100644
--- a/include/ircd/m/room.h
+++ b/include/ircd/m/room.h
@@ -153,10 +153,12 @@ struct ircd::m::room
 	void get(const string_view &type, const event::closure &) const;
 	bool has(const string_view &type) const;
 
-	// misc
+	// misc / convenience utils
 	bool membership(const m::id::user &, const string_view &membership = "join") const;
 	string_view membership(const mutable_buffer &out, const m::id::user &) const;
 	bool visible(const string_view &mxid, const m::event *const & = nullptr) const;
+	string_view join_rule(const mutable_buffer &out) const;
+	bool join_rule(const string_view &rule) const;
 	bool lonly() const;
 
 	room(const id &room_id,
diff --git a/ircd/m/room.cc b/ircd/m/room.cc
index 664193838..3f462d2fd 100644
--- a/ircd/m/room.cc
+++ b/ircd/m/room.cc
@@ -263,6 +263,70 @@ ircd::m::my(const room &room)
 // room
 //
 
+/// Test of the join_rule of the room is the argument.
+bool
+ircd::m::room::join_rule(const string_view &rule)
+const
+{
+	char buf[32];
+	return join_rule(mutable_buffer{buf}) == rule;
+}
+
+/// Receive the join_rule of the room into buffer of sufficient size.
+/// The protocol does not specify a join_rule string longer than 7
+/// characters but do be considerate of the future. This function
+/// properly defaults the string as per the protocol spec.
+ircd::string_view
+ircd::m::room::join_rule(const mutable_buffer &out)
+const
+{
+	static const string_view default_join_rule
+	{
+		"invite"
+	};
+
+	string_view ret
+	{
+		default_join_rule
+	};
+
+	const event::keys::include keys
+	{
+		"content"
+	};
+
+	const m::event::fetch::opts fopts
+	{
+		keys, this->fopts? this->fopts->gopts : db::gopts{}
+	};
+
+	const room::state state
+	{
+		*this, &fopts
+	};
+
+	state.get(std::nothrow, "m.room.join_rules", "", [&ret, &out]
+	(const m::event &event)
+	{
+		const auto &content
+		{
+			json::get<"content"_>(event)
+		};
+
+		const string_view &rule
+		{
+			content.get("join_rule", default_join_rule)
+		};
+
+		ret = string_view
+		{
+			data(out), copy(out, unquote(rule))
+		};
+	});
+
+	return ret;
+}
+
 /// The only joined members are from our origin (local only). This indicates
 /// we won't have any other federation servers to query for room data, nor do
 /// we need to broadcast events to the federation. This is not an authority