From 60f983b9532c21c660a711937785bce398a24225 Mon Sep 17 00:00:00 2001
From: Jason Volk <jason@zemos.net>
Date: Tue, 3 Apr 2018 14:50:47 -0700
Subject: [PATCH] modules/federation: Add make_join endpoint handler.

---
 modules/Makefile.am             |   2 +
 modules/federation/make_join.cc | 127 ++++++++++++++++++++++++++++++++
 2 files changed, 129 insertions(+)
 create mode 100644 modules/federation/make_join.cc

diff --git a/modules/Makefile.am b/modules/Makefile.am
index 2eb00b8bb..cf5e33f46 100644
--- a/modules/Makefile.am
+++ b/modules/Makefile.am
@@ -243,6 +243,7 @@ federation_federation_version_la_SOURCES = federation/version.cc
 federation_federation_sender_la_SOURCES = federation/sender.cc
 federation_federation_query_la_SOURCES = federation/query.cc
 federation_federation_invite_la_SOURCES = federation/invite.cc
+federation_federation_make_join_la_SOURCES = federation/make_join.cc
 
 federation_module_LTLIBRARIES = \
 	federation/federation_send.la \
@@ -253,6 +254,7 @@ federation_module_LTLIBRARIES = \
 	federation/federation_sender.la \
 	federation/federation_query.la \
 	federation/federation_invite.la \
+	federation/federation_make_join.la \
 	###
 
 ###############################################################################
diff --git a/modules/federation/make_join.cc b/modules/federation/make_join.cc
new file mode 100644
index 000000000..b28b81f63
--- /dev/null
+++ b/modules/federation/make_join.cc
@@ -0,0 +1,127 @@
+// Matrix Construct
+//
+// Copyright (C) Matrix Construct Developers, Authors & Contributors
+// Copyright (C) 2016-2018 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.
+
+using namespace ircd;
+
+mapi::header
+IRCD_MODULE
+{
+	"Federation :Request a prototype for creating a join event."
+};
+
+const string_view
+make_join_description
+{R"(
+
+Sends a partial event to the remote with enough information for them to
+create a join event 'in the blind' for one of their users.
+
+)"};
+
+resource
+make_join_resource
+{
+	"/_matrix/federation/v1/make_join/",
+	{
+		make_join_description,
+		resource::DIRECTORY
+	}
+};
+
+resource::response
+get__make_join(client &client,
+                const resource::request &request)
+{
+	if(request.parv.size() < 1)
+		throw m::NEED_MORE_PARAMS
+		{
+			"room_id path parameter required"
+		};
+
+	m::room::id::buf room_id
+	{
+		url::decode(request.parv[0], room_id)
+	};
+
+	if(request.parv.size() < 2)
+		throw m::NEED_MORE_PARAMS
+		{
+			"user_id path parameter required"
+		};
+
+	m::user::id::buf user_id
+	{
+		url::decode(request.parv[1], user_id)
+	};
+
+	uint64_t depth;
+	const m::event::id::buf prev_event_id
+	{
+		m::head(room_id, depth)
+	};
+
+	const m::event::fetch evf
+	{
+		prev_event_id, std::nothrow
+	};
+
+	const auto &auth_events
+	{
+		json::get<"auth_events"_>(evf)?
+			json::get<"auth_events"_>(evf) : json::array{"[]"}
+	};
+
+	const json::value prev[]
+	{
+		{ string_view{prev_event_id}  },
+		{ json::get<"hashes"_>(evf) }
+	};
+
+	const json::value prevs[]
+	{
+		{ prev, 2 }
+	};
+
+	thread_local char bufs[96_KiB];
+	mutable_buffer buf{bufs};
+
+	json::iov content, event, wrapper;
+	const json::iov::push push[]
+	{
+		{ event,    { "origin",            request.origin            }},
+		{ event,    { "origin_server_ts",  time<milliseconds>()      }},
+		{ event,    { "room_id",           room_id                   }},
+		{ event,    { "type",              "m.room.member"           }},
+		{ event,    { "state_key",         user_id                   }},
+		{ event,    { "sender",            user_id                   }},
+		{ event,    { "depth",             int64_t(depth) + 1        }},
+		{ event,    { "membership",        "join"                    }},
+		{ content,  { "membership",        "join"                    }},
+		{ event,    { "auth_events",       auth_events               }},
+		{ event,    { "prev_state",        "[]"                      }},
+		{ event,    { "prev_events",       { prevs, 1 }              }},
+		{ event,    { "content",           stringify(buf, content)   }},
+		{ wrapper,  { "event",             stringify(buf, event)     }},
+	};
+
+	return resource::response
+	{
+		client, wrapper
+	};
+}
+
+resource::method
+method_get
+{
+	make_join_resource, "GET", get__make_join,
+	{
+		method_get.VERIFY_ORIGIN
+	}
+};