only rewrite redirect urls when it matches target

if functioning as a reverse proxy for host1.foo.com,
with a backend target of backend.foo.com:8080, the
node proxy should only rewrite the redirect if it is
a redirect to somewhere on backend.foo.com:8080

lib/http-proxy/passes/web-outgoing.js

@@ -50,7 +50,14 @@ var redirectRegex = /^30(1|2|7|8)$/;
     if ((options.hostRewrite || options.autoRewrite || options.protocolRewrite)
         && proxyRes.headers['location']
         && redirectRegex.test(proxyRes.statusCode)) {
+      var target = url.parse(options.target);
       var u = url.parse(proxyRes.headers['location']);
+
+      // make sure the redirected host matches the target host before rewriting
+      if (target.host != u.host) {
+        return;
+      }
+
       if (options.hostRewrite) {
         u.host = options.hostRewrite;
       } else if (options.autoRewrite) {

test/lib-http-proxy-passes-web-outgoing-test.js

@@ -49,6 +49,20 @@ describe('lib/http-proxy/passes/web-outgoing.js', function () {
         httpProxy.setRedirectHostRewrite(this.req, {}, this.proxyRes, this.options);
         expect(this.proxyRes.headers.location).to.eql('http://ext-manual.com/');
       });
+
+      it('not when the redirected location does not match target host', function() {
+        this.proxyRes.statusCode = 302;
+        this.proxyRes.headers.location = "http://some-other/";
+        httpProxy.setRedirectHostRewrite(this.req, {}, this.proxyRes, this.options);
+        expect(this.proxyRes.headers.location).to.eql('http://some-other/');
+      });
+
+      it('not when the redirected location does not match target port', function() {
+        this.proxyRes.statusCode = 302;
+        this.proxyRes.headers.location = "http://backend.com:8080/";
+        httpProxy.setRedirectHostRewrite(this.req, {}, this.proxyRes, this.options);
+        expect(this.proxyRes.headers.location).to.eql('http://backend.com:8080/');
+      });
     });
 
     context('rewrites location host with autoRewrite', function() {
@@ -74,6 +88,20 @@ describe('lib/http-proxy/passes/web-outgoing.js', function () {
         httpProxy.setRedirectHostRewrite(this.req, {}, this.proxyRes, this.options);
         expect(this.proxyRes.headers.location).to.eql('http://backend.com/');
       });
+
+      it('not when the redirected location does not match target host', function() {
+        this.proxyRes.statusCode = 302;
+        this.proxyRes.headers.location = "http://some-other/";
+        httpProxy.setRedirectHostRewrite(this.req, {}, this.proxyRes, this.options);
+        expect(this.proxyRes.headers.location).to.eql('http://some-other/');
+      });
+
+      it('not when the redirected location does not match target port', function() {
+        this.proxyRes.statusCode = 302;
+        this.proxyRes.headers.location = "http://backend.com:8080/";
+        httpProxy.setRedirectHostRewrite(this.req, {}, this.proxyRes, this.options);
+        expect(this.proxyRes.headers.location).to.eql('http://backend.com:8080/');
+      });
     });
 
     context('rewrites location protocol with protocolRewrite', function() {