mod_external_services: XEP-0215: External Service Discovery

5 files changed, 284 insertions, 0 deletions

diff --git a/CHANGES b/CHANGES
index d1e50abb..080ee3d7 100644
--- a/CHANGES
+++ b/CHANGES
@@ -17,6 +17,7 @@ TRUNK
 -   `daemonize` option deprecated
 -   SASL DIGEST-MD5 removed
 -   Switch to libunbound for DNS queries
+-   mod_external_services (XEP-0215)
 
 0.11.0
 ======
diff --git a/doc/doap.xml b/doc/doap.xml
index ef1437e7..6024903f 100644
--- a/doc/doap.xml
+++ b/doc/doap.xml
@@ -416,6 +416,15 @@
     </implements>
     <implements>
       <xmpp:SupportedXep>
+        <xmpp:xep rdf:resource="https://xmpp.org/extensions/xep-0215.html"/>
+        <xmpp:version>0.7</xmpp:version>
+        <xmpp:status>complete</xmpp:status>
+        <xmpp:since>0.12</xmpp:since>
+        <xmpp:note>mod_external_services</xmpp:note>
+      </xmpp:SupportedXep>
+    </implements>
+    <implements>
+      <xmpp:SupportedXep>
         <xmpp:xep rdf:resource="https://xmpp.org/extensions/xep-0220.html"/>
         <xmpp:since>0.1</xmpp:since>
       </xmpp:SupportedXep>
diff --git a/plugins/mod_external_services.lua b/plugins/mod_external_services.lua
new file mode 100644
index 00000000..51d2d313
--- /dev/null
+++ b/plugins/mod_external_services.lua
@@ -0,0 +1,205 @@
+
+local dt = require "util.datetime";
+local base64 = require "util.encodings".base64;
+local hashes = require "util.hashes";
+local st = require "util.stanza";
+local jid = require "util.jid";
+
+local default_host = module:get_option_string("external_service_host", module.host);
+local default_port = module:get_option_number("external_service_port");
+local default_secret = module:get_option_string("external_service_secret");
+local default_ttl = module:get_option_number("external_service_ttl", 86400);
+
+local configured_services = module:get_option_array("external_services", {});
+
+local access = module:get_option_set("external_service_access", {});
+
+-- filter config into well-defined service records
+local function prepare(item)
+	if type(item) ~= "table" then
+		module:log("error", "Service definition is not a table: %q", item);
+		return nil;
+	end
+
+	local srv = {
+		type = nil;
+		transport = nil;
+		host = default_host;
+		port = default_port;
+		username = nil;
+		password = nil;
+		restricted = nil;
+		expires = nil;
+	};
+
+	if type(item.type) == "string" then
+		srv.type = item.type;
+	else
+		module:log("error", "Service missing mandatory 'type' field: %q", item);
+		return nil;
+	end
+	if type(item.transport) == "string" then
+		srv.transport = item.transport;
+	end
+	if type(item.host) == "string" then
+		srv.host = item.host;
+	end
+	if type(item.port) == "number" then
+		srv.port = item.port;
+	end
+	if type(item.username) == "string" then
+		srv.username = item.username;
+	end
+	if type(item.password) == "string" then
+		srv.password = item.password;
+		srv.restricted = true;
+	end
+	if item.restricted == true then
+		srv.restricted = true;
+	end
+	if type(item.expires) == "number" then
+		srv.expires = item.expires;
+	elseif type(item.ttl) == "number" then
+		srv.expires = os.time() + item.ttl;
+	end
+	if (item.secret == true and default_secret) or type(item.secret) == "string" then
+		local ttl = default_ttl;
+		if type(item.ttl) == "number" then
+			ttl = item.ttl;
+		end
+		local expires = os.time() + ttl;
+		local secret = item.secret;
+		if secret == true then
+			secret = default_secret;
+		end
+		local username;
+		if type(item.username) == "string" then
+			username = string.format("%d:%s", expires, item.username);
+		else
+			username = string.format("%d", expires);
+		end
+		srv.username = username;
+		srv.password = base64.encode(hashes.hmac_sha1(secret, srv.username));
+		srv.restricted = true;
+	end
+	return srv;
+end
+
+function module.load()
+	-- Trigger errors on startup
+	local services = configured_services / prepare;
+	if #services == 0 then
+		module:log("warn", "No services configured or all had errors");
+	end
+end
+
+local function handle_services(event)
+	local origin, stanza = event.origin, event.stanza;
+	local action = stanza.tags[1];
+
+	local user_bare = jid.bare(stanza.attr.from);
+	local user_host = jid.host(user_bare);
+	if not ((access:empty() and origin.type == "c2s") or access:contains(user_bare) or access:contains(user_host)) then
+		origin.send(st.error_reply(stanza, "auth", "forbidden"));
+		return true;
+	end
+
+	local reply = st.reply(stanza):tag("services", { xmlns = action.attr.xmlns });
+	local services = configured_services / prepare;
+
+	local requested_type = action.attr.type;
+	if requested_type then
+		services:filter(function(item)
+			return item.type == requested_type;
+		end);
+	end
+
+	module:fire_event("external_service/services", {
+			origin = origin;
+			stanza = stanza;
+			reply = reply;
+			requested_type = requested_type;
+			services = services;
+		});
+
+	for _, srv in ipairs(services) do
+		reply:tag("service", {
+				type = srv.type;
+				transport = srv.transport;
+				host = srv.host;
+				port = srv.port and string.format("%d", srv.port) or nil;
+				username = srv.username;
+				password = srv.password;
+				expires = srv.expires and dt.datetime(srv.expires) or nil;
+				restricted = srv.restricted and "1" or nil;
+			}):up();
+	end
+
+	origin.send(reply);
+	return true;
+end
+
+local function handle_credentials(event)
+	local origin, stanza = event.origin, event.stanza;
+	local action = stanza.tags[1];
+
+	if origin.type ~= "c2s" then
+		origin.send(st.error_reply(stanza, "auth", "forbidden"));
+		return true;
+	end
+
+	local reply = st.reply(stanza):tag("credentials", { xmlns = action.attr.xmlns });
+	local services = configured_services / prepare;
+	services:filter(function (item)
+		return item.restricted;
+	end)
+
+	local requested_credentials = {};
+	for service in action:childtags("service") do
+		table.insert(requested_credentials, {
+				type = service.attr.type;
+				host = service.attr.host;
+				port = tonumber(service.attr.port);
+			});
+	end
+
+	module:fire_event("external_service/credentials", {
+			origin = origin;
+			stanza = stanza;
+			reply = reply;
+			requested_credentials = requested_credentials;
+			services = services;
+		});
+
+	for req_srv in action:childtags("service") do
+		for _, srv in ipairs(services) do
+			if srv.type == req_srv.attr.type and srv.host == req_srv.attr.host
+				and not req_srv.attr.port or srv.port == tonumber(req_srv.attr.port) then
+				reply:tag("service", {
+						type = srv.type;
+						transport = srv.transport;
+						host = srv.host;
+						port = srv.port and string.format("%d", srv.port) or nil;
+						username = srv.username;
+						password = srv.password;
+						expires = srv.expires and dt.datetime(srv.expires) or nil;
+						restricted = srv.restricted and "1" or nil;
+					}):up();
+			end
+		end
+	end
+
+	origin.send(reply);
+	return true;
+end
+
+-- XEP-0215 v0.7
+module:add_feature("urn:xmpp:extdisco:2");
+module:hook("iq-get/host/urn:xmpp:extdisco:2:services", handle_services);
+module:hook("iq-get/host/urn:xmpp:extdisco:2:credentials", handle_credentials);
+
+-- COMPAT XEP-0215 v0.6
+-- Those still on the old version gets to deal with undefined attributes until they upgrade.
+module:add_feature("urn:xmpp:extdisco:1");
+module:hook("iq-get/host/urn:xmpp:extdisco:1:services", handle_services);
+module:hook("iq-get/host/urn:xmpp:extdisco:1:credentials", handle_credentials);
diff --git a/spec/scansion/extdisco.scs b/spec/scansion/extdisco.scs
new file mode 100644
index 00000000..fd73c9da
--- /dev/null
+++ b/spec/scansion/extdisco.scs
@@ -0,0 +1,57 @@
+# XEP-0215: External Service Discovery
+
+[Client] Romeo
+	password: password
+	jid: user@localhost/mFquWxSr
+
+-----
+
+Romeo connects
+
+Romeo sends:
+	<iq type='get' xml:lang='sv' id='lx2' to='localhost'>
+		<services xmlns='urn:xmpp:extdisco:2'/>
+	</iq>
+
+Romeo receives:
+	<iq type='result' id='lx2' from='localhost'>
+		<services xmlns='urn:xmpp:extdisco:2'>
+			<service host='default.example' transport='udp' port='9876' type='stun'/>
+			<service port='9876' type='turn' restricted='1' password='yHYYBDN7M3mdlug0LTdJbW0GvvQ=' transport='udp' host='default.example' username='1219525744'/>
+			<service port='9876' type='turn' restricted='1' password='1Uc6QfrDhIlbK97rGCUQ/cUICxs=' transport='udp' host='default.example' username='1219525744'/>
+			<service port='2121' type='ftp' restricted='1' password='password' transport='tcp' host='default.example' username='john'/>
+			<service port='21' type='ftp' restricted='1' password='password' transport='tcp' host='ftp.example.com' username='john'/>
+		</services>
+	</iq>
+
+Romeo sends:
+	<iq type='get' xml:lang='sv' id='lx3' to='localhost'>
+		<services xmlns='urn:xmpp:extdisco:2' type='ftp'/>
+	</iq>
+
+Romeo receives:
+	<iq type='result' id='lx3' from='localhost'>
+		<services xmlns='urn:xmpp:extdisco:2'>
+			<service port='2121' type='ftp' restricted='1' password='password' transport='tcp' host='default.example' username='john'/>
+			<service port='21' type='ftp' restricted='1' password='password' transport='tcp' host='ftp.example.com' username='john'/>
+		</services>
+	</iq>
+
+Romeo sends:
+	<iq type='get' xml:lang='sv' id='lx4' to='localhost'>
+		<credentials xmlns='urn:xmpp:extdisco:2'>
+			<service host='default.example' type='turn'/>
+		</credentials>
+	</iq>
+
+Romeo receives:
+	<iq type='result' id='lx4' from='localhost'>
+		<credentials xmlns='urn:xmpp:extdisco:2'>
+			<service port='9876' type='turn' restricted='1' password='yHYYBDN7M3mdlug0LTdJbW0GvvQ=' transport='udp' host='default.example' username='1219525744'/>
+			<service port='9876' type='turn' restricted='1' password='1Uc6QfrDhIlbK97rGCUQ/cUICxs=' transport='udp' host='default.example' username='1219525744'/>
+		</credentials>
+	</iq>
+
+Romeo disconnects
+
+# recording ended on 2020-07-18T16:47:57Z
diff --git a/spec/scansion/prosody.cfg.lua b/spec/scansion/prosody.cfg.lua
index 0bf68ddb..4e43d312 100644
--- a/spec/scansion/prosody.cfg.lua
+++ b/spec/scansion/prosody.cfg.lua
@@ -62,6 +62,7 @@ modules_enabled = {
 		--"legacyauth"; -- Legacy authentication. Only used by some old clients and bots.
 		--"proxy65"; -- Enables a file transfer proxy service which clients behind NAT can use
 		"lastactivity";
+		"external_services";
 
 	-- Useful for testing
 		--"scansion_record"; -- Records things that happen in scansion test case format
@@ -77,6 +78,17 @@ contact_info = {
 	support = { "https://localhost/support.html", "xmpp:support@localhost" };
 }
 
+external_service_host = "default.example"
+external_service_port = 9876
+external_service_secret = "<secret>"
+external_services = {
+	{type = "stun"; transport = "udp"};
+	{type = "turn"; transport = "udp"; secret = true};
+	{type = "turn"; transport = "udp"; secret = "foo"};
+	{type = "ftp"; transport = "tcp"; port = 2121; username = "john"; password = "password"};
+	{type = "ftp"; transport = "tcp"; host = "ftp.example.com"; port = 21; username = "john"; password = "password"};
+}
+
 modules_disabled = {
 	"s2s";
 }