ircd:Ⓜ️:event::auth: Add auth chain traversal.

include/ircd/m/event/auth.h

@@ -18,6 +18,7 @@ namespace ircd::m
 
 struct ircd::m::event::auth
 {
+	struct chain;
 
 	event::idx idx;
 
@@ -40,10 +41,17 @@ struct ircd::m::event::auth
 	}
 };
 
-inline
-ircd::m::event::auth::auth(const event::idx &idx)
-noexcept
-:idx{idx}
+struct ircd::m::event::auth::chain
 {
-	assert(idx);
-}
+	event::auth auth;
+
+  public:
+	using closure = std::function<event::idx (const event::idx &)>;
+
+	bool for_each(const string_view &type, const closure &) const;
+	bool for_each(const closure &) const;
+
+	chain(const event::idx &idx)
+	:auth{idx}
+	{}
+};

ircd/m_event.cc

@@ -1125,6 +1125,32 @@ ircd::m::is_power_event(const m::event &event)
 	return false;
 }
 
+//
+// event::auth::chain
+//
+
+bool
+ircd::m::event::auth::chain::for_each(const closure &closure)
+const
+{
+	return for_each(string_view{}, closure);
+}
+
+bool
+ircd::m::event::auth::chain::for_each(const string_view &type,
+                                      const closure &c)
+const
+{
+	using prototype = bool (event::auth, const string_view &, const closure &);
+
+	static mods::import<prototype> auth_chain_for_each
+	{
+		"m_event", "auth_chain_for_each"
+	};
+
+	return auth_chain_for_each(auth, type, c);
+}
+
 //
 // event::auth
 //

modules/console.cc

@@ -5917,6 +5917,31 @@ console_cmd__event__auth(opt &out, const string_view &line)
 	return true;
 }
 
+bool
+console_cmd__event__auth__chain(opt &out, const string_view &line)
+{
+	const params param{line, " ",
+	{
+		"event_id", "type"
+	}};
+
+	const m::event::id &event_id
+	{
+		param.at("event_id")
+	};
+
+	const string_view type
+	{
+		param.at("type", ""_sv)
+	};
+
+	const m::event::auth::chain auth
+	{
+		index(event_id)
+	};
+
+	auth.for_each(type, [&out]
+	(const m::event::idx &idx)
 	{
 		const m::event::fetch event
 		{

modules/m_event.cc

@@ -682,3 +682,35 @@ event_auth__rebuild()
 
 	txn();
 }
+
+extern "C" bool
+auth_chain_for_each(event::auth auth,
+                    const string_view &type,
+                    const event::auth::chain::closure &closure)
+{
+	event::idx next(0);
+	uint64_t depth[2] {uint64_t(-1), 0}; do
+	{
+		auth.for_each(type, [&depth, &next]
+		(const event::idx &event_idx)
+		{
+			if(!m::get(event_idx, "depth", depth[1]))
+				return true;
+
+			if(depth[1] >= depth[0])
+				return true;
+
+			depth[0] = depth[1];
+			next = event_idx;
+			return true;
+		});
+
+		if(!closure(next))
+			return false;
+
+		auth.idx = next;
+		next = 0;
+	}
+	while(auth.idx);
+	return true;
+}