swagger: use X-Forwarded-Host for basePath

lib/swagger.js

@@ -114,12 +114,14 @@ function addRoute(app, uri, doc, opts) {
     // can't guarantee this path is either reachable or desirable if it's set
     // as a part of the options.
     //
-    // The simplest way around this is to reflect the value of the `Host` HTTP
-    // header as the `basePath`. Because we pre-build the Swagger data, we don't
-    // know that header at the time the data is built.
+    // The simplest way around this is to reflect the value of the `Host` and/or
+    // `X-Forwarded-Host` HTTP headers as the `basePath`.
+    // Because we pre-build the Swagger data, we don't know that header at
+    // the time the data is built.
     if (hasBasePath) {
       var headers = req.headers;
-      var host = headers.Host || headers.host;
+      // NOTE header names (keys) are always all-lowercase
+      var host = headers['x-forwarded-host'] || headers.host;
       doc.basePath = (opts.protocol || req.protocol) + '://' +
         host + initialPath;
     }

test/swagger.test.js

@@ -81,6 +81,18 @@ describe('swagger definition', function() {
         done();
       });
     });
+
+    it('respects X-Forwarded-Host header (behind a proxy)', function(done) {
+      var app = mountSwagger();
+      getAPIDeclaration(app, 'products')
+        .set('X-Forwarded-Host', 'example.com')
+        .end(function(err, res) {
+          if (err) return done(err);
+          var baseUrl = url.parse(res.body.basePath);
+          expect(baseUrl.hostname).to.equal('example.com');
+          done();
+        });
+    });
   });
 
   describe('Model definition attributes', function() {