Support InResponseTo validations in MultiSaml

Either use cache provided by user, or a default memory
cache to store InResponse parameters. This cache is not
yet partitioned per provider, which means a malicious
provider could do replay attacks by using anothers
unconsummed `InResponse` values

node-saml#334

README.md

@@ -72,6 +72,11 @@ passport.use(new MultiSamlStrategy(
   })
 );
 ```
+The options passed when the `MultiSamlStrategy` is initialized are also passed as default values to each provider.
+e.g. If you provide an `issuer` on `MultiSamlStrategy`, this will be also a default value for every provider.
+You can override these defaults by passing a new value through the `getSamlOptions` function.
+
+Using multiple providers supports `validateInResponseTo`, but all the `InResponse` values are stored on the same Cache. This means, if you're using the default `InMemoryCache`, that all providers have access to it and a provider might get its response validated against another's request. [Issue Report](!https://github.com/bergie/passport-saml/issues/334). To amend this you should provide a different cache provider per SAML provider, through the `getSamlOptions` function.
 
 #### The profile object:
 

multiSamlStrategy.js

@@ -1,40 +1,50 @@
 var util = require('util');
 var saml = require('./lib/passport-saml/saml');
+var InMemoryCacheProvider = require('./lib/passport-saml/inmemory-cache-provider').CacheProvider;
 var SamlStrategy = require('./lib/passport-saml/strategy');
 
 function MultiSamlStrategy (options, verify) {
   if (!options || typeof options.getSamlOptions != 'function') {
     throw new Error('Please provide a getSamlOptions function');
   }
 
+  if(!options.requestIdExpirationPeriodMs){
+    options.requestIdExpirationPeriodMs = 28800000;  // 8 hours
+  }
+
+  if(!options.cacheProvider){
+      options.cacheProvider = new InMemoryCacheProvider(
+          {keyExpirationPeriodMs: options.requestIdExpirationPeriodMs });
+  }
+
   SamlStrategy.call(this, options, verify);
-  this._getSamlOptions = options.getSamlOptions;
+  this._options = options;
 }
 
 util.inherits(MultiSamlStrategy, SamlStrategy);
 
 MultiSamlStrategy.prototype.authenticate = function (req, options) {
   var self = this;
 
-  this._getSamlOptions(req, function (err, samlOptions) {
+  this._options.getSamlOptions(req, function (err, samlOptions) {
     if (err) {
       return self.error(err);
     }
 
-    self._saml = new saml.SAML(samlOptions);
+    self._saml = new saml.SAML(Object.assign({}, self._options, samlOptions));
     self.constructor.super_.prototype.authenticate.call(self, req, options);
   });
 };
 
 MultiSamlStrategy.prototype.logout = function (req, options) {
   var self = this;
 
-  this._getSamlOptions(req, function (err, samlOptions) {
+  this._options.getSamlOptions(req, function (err, samlOptions) {
     if (err) {
       return self.error(err);
     }
 
-    self._saml = new saml.SAML(samlOptions);
+    self._saml = new saml.SAML(Object.assign({}, self._options, samlOptions));
     self.constructor.super_.prototype.logout.call(self, req, options);
   });
 };

test/multiSamlStrategy.js

@@ -37,7 +37,9 @@ describe('strategy#authenticate', function() {
       done();
     };
 
-    var strategy = new MultiSamlStrategy({ getSamlOptions: getSamlOptions }, verify);
+    var strategy = new MultiSamlStrategy({
+      getSamlOptions: getSamlOptions
+    }, verify);
     strategy.authenticate();
   });
 
@@ -57,7 +59,7 @@ describe('strategy#authenticate', function() {
     strategy.authenticate();
   });
 
-  it('uses geted options to setup internal saml provider', function(done) {
+  it('uses given options to setup internal saml provider', function(done) {
     var samlOptions = {
       issuer: 'http://foo.issuer',
       callbackUrl: 'http://foo.callback',
@@ -73,12 +75,15 @@ describe('strategy#authenticate', function() {
 
     function getSamlOptions (req, fn) {
       fn(null, samlOptions);
-      strategy._saml.options.should.containEql(samlOptions);
+      strategy._saml.options.should.containEql(Object.assign({},
+        cacheProvider: 'mock cache provider',
+        samlOptions
+      ));
       done();
     }
 
     var strategy = new MultiSamlStrategy(
-      { getSamlOptions: getSamlOptions },
+      { getSamlOptions: getSamlOptions, cacheProvider: 'mock cache provider'},
       verify
     );
     strategy.authenticate();
@@ -122,7 +127,7 @@ describe('strategy#logout', function() {
     strategy.logout();
   });
 
-  it('uses geted options to setup internal saml provider', function(done) {
+  it('uses given options to setup internal saml provider', function(done) {
     var samlOptions = {
       issuer: 'http://foo.issuer',
       callbackUrl: 'http://foo.callback',