get correct expiry for multi-contact registraitons (#149)

lib/regbot.js

@@ -9,6 +9,7 @@ const {
   JAMBONES_REGBOT_REGISTER_FAILURE_THRESHOLD
 } = require('./config');
 const {isValidDomainOrIP, isValidIPv4} = require('./utils');
+const parseUri = require('drachtio-srf').parseUri;
 const DEFAULT_EXPIRES = (parseInt(JAMBONES_REGBOT_DEFAULT_EXPIRES_INTERVAL) || 3600);
 const MIN_EXPIRES = (parseInt(JAMBONES_REGBOT_MIN_EXPIRES_INTERVAL) || 90);
 const FAILURE_RETRY_INTERVAL = (parseInt(JAMBONES_REGBOT_FAILURE_RETRY_INTERVAL) || 300);
@@ -17,6 +18,38 @@ const assert = require('assert');
 const version = require('../package.json').version;
 const useragent = JAMBONES_REGBOT_USER_AGENT || `Jambonz ${version}`;
 
+/**
+ * A 200 OK to a REGISTER may echo back every Contact bound to the AoR, not just ours
+ * (e.g. when another device is registered against the same account). Per RFC 3261 10.2.4
+ * we must refresh based on the expires of *our own* binding, so locate the returned Contact
+ * whose user and host match the Contact we sent.
+ * Returns the parsed expires (a number) of our binding, or undefined if it can't be matched.
+ */
+const getOwnContactExpires = (contacts, ownContactUri) => {
+  let own;
+  try {
+    own = parseUri(ownContactUri);
+  } catch {
+    return undefined;
+  }
+  if (!own || !own.host) return undefined;
+  const ownUser = own.user;
+  const ownHost = own.host.toLowerCase();
+  for (const c of contacts) {
+    let u;
+    try {
+      u = parseUri(c.uri);
+    } catch {
+      continue;
+    }
+    if (u && u.user === ownUser && (u.host || '').toLowerCase() === ownHost &&
+        c.params && c.params.expires !== undefined) {
+      return parseInt(c.params.expires);
+    }
+  }
+  return undefined;
+};
+
 class Regbot {
   constructor(logger, opts) {
     this.logger = logger;
@@ -235,9 +268,18 @@ class Regbot {
           }
 
           if (res.has('Contact')) {
-            const contact = res.getParsedHeader('Contact');
-            if (contact.length > 0 && contact[0].params && contact[0].params.expires) {
-              expires = parseInt(contact[0].params.expires);
+            const contacts = res.getParsedHeader('Contact');
+            const ownExpires = getOwnContactExpires(contacts, `${scheme}:${contactAddress}`);
+            if (typeof ownExpires === 'number' && !isNaN(ownExpires)) {
+              // refresh based on our own binding's expires
+              expires = ownExpires;
+            } else if (contacts.length === 1 && contacts[0].params && contacts[0].params.expires) {
+              // single binding returned: safe to use even if the registrar rewrote the contact host
+              expires = parseInt(contacts[0].params.expires);
+            } else if (contacts.length > 1) {
+              this.logger.info({aor: this.aor, ipv4: this.ipv4, port: this.port},
+                // eslint-disable-next-line max-len
+                `200 OK returned ${contacts.length} contacts but none matched our own binding; using expires ${expires}`);
             }
           } else {
             this.logger.debug({ aor: this.aor, ipv4: this.ipv4, port: this.port },
@@ -355,5 +397,8 @@ const dnsResolverSrv = async(logger, hostname, transport) => {
 };
 
 
+// exposed for unit testing
+Regbot._getOwnContactExpires = getOwnContactExpires;
+
 module.exports = Regbot;