client: session-establishment (#369)

packages/client/lib/plugins.js

@@ -12,6 +12,7 @@
   'tcp',
   'reconnect',
   'starttls',
+  'session-establishment',
 ].forEach((pkg) => {
   module.exports[pkg] = require('@xmpp/plugins/' + pkg)
 })

packages/plugins/session-establishment/index.js

@@ -0,0 +1,36 @@
+'use strict'
+
+const xml = require('@xmpp/xml')
+const streamfeatures = require('../stream-features')
+const iqCaller = require('../iq-caller')
+
+/*
+ * References
+ * https://tools.ietf.org/html/draft-cridland-xmpp-session-01
+ */
+
+const NS = 'urn:ietf:params:xml:ns:xmpp-session'
+
+function match (features) {
+  const session = features.getChild('session', NS)
+  return session && !session.getChild('optional')
+}
+
+module.exports.name = 'session-establishment'
+module.exports.plugin = function plugin (entity) {
+  const caller = entity.plugin(iqCaller)
+
+  const streamFeature = {
+    priority: 2000,
+    match,
+    run: (entity) => {
+      return caller.set(null, xml`<session xmlns='${NS}'/>`)
+    }
+  }
+
+  const streamFeatures = entity.plugin(streamfeatures)
+  streamFeatures.add(streamFeature)
+  return {
+    entity
+  }
+}