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;
 

test/regbot-unit-test.js

@@ -149,6 +149,54 @@ test('configKey returns different strings when config differs', (t) => {
   t.end();
 });
 
+test('getOwnContactExpires: picks our own binding when registrar returns multiple contacts', (t) => {
+  const getOwnContactExpires = Regbot._getOwnContactExpires;
+
+  // reproduces EMF capture: AoR 9955 has another device registered against it (rinstance
+  // contact with a counting-down expires). Our own contact is always granted 300.
+  const contacts = [
+    {uri: 'sip:9955@192.168.1.50:15447;rinstance=D4077321', params: {expires: '18', received: '"sip:192.168.100.186:15447"'}},
+    {uri: 'sip:9955@example.com;transport=udp', params: {expires: '300'}}
+  ];
+  t.equal(getOwnContactExpires(contacts, 'sip:9955@example.com'), 300,
+    'returns our own binding expires (300), not the other device countdown (18)');
+
+  // order should not matter
+  const reversed = [contacts[1], contacts[0]];
+  t.equal(getOwnContactExpires(reversed, 'sip:9955@example.com'), 300,
+    'matches our contact regardless of position in the header');
+
+  // host match is case-insensitive
+  t.equal(getOwnContactExpires(contacts, 'sip:9955@EXAMPLE.COM'), 300,
+    'host comparison is case-insensitive');
+
+  t.end();
+});
+
+test('getOwnContactExpires: returns undefined when our contact is absent', (t) => {
+  const getOwnContactExpires = Regbot._getOwnContactExpires;
+  const contacts = [
+    {uri: 'sip:9955@192.168.1.50:15447;rinstance=D4077321', params: {expires: '18'}}
+  ];
+  t.equal(getOwnContactExpires(contacts, 'sip:9955@example.com'), undefined,
+    'no match -> undefined so caller can fall back to Expires header / single-contact');
+
+  t.equal(getOwnContactExpires([], 'sip:9955@example.com'), undefined,
+    'empty contact list -> undefined');
+  t.end();
+});
+
+test('getOwnContactExpires: single matching contact returns its expires', (t) => {
+  const getOwnContactExpires = Regbot._getOwnContactExpires;
+  // AoR 25337 in the same capture: only our binding present
+  const contacts = [
+    {uri: 'sip:25337@example.com;transport=udp', params: {expires: '300'}}
+  ];
+  t.equal(getOwnContactExpires(contacts, 'sip:25337@example.com'), 300,
+    'single own binding resolves correctly');
+  t.end();
+});
+
 test('stopTimer clears timer without deleting gateways', (t) => {
   const rb = new Regbot(logger, {
     voip_carrier_sid: 'carrier-1',