grunt-connect-rewrite.js

    var fs = require('fs'),
    url = require('url');

    module.exports = function (rootDir, indexFile) {
    indexFile = indexFile || "index.html";
    rootDir = rootDir || '';
    var rootPart = rootDir.length > 0 ? rootDir + '/' : '';

    return function(req, res, next){
      var path = url.parse(req.url).pathname;

      fs.readFile('./' + rootDir + path, function(err, buf){
        if (!err) return next();

          fs.readFile('./' + rootPart + indexFile, function (error, buffer) {
            if (error) return next(error);

            resp = {
              headers: {
                  'Content-Type': 'text/html',
                  'Content-Length': buffer.length
              },
              body: buffer
            };
            res.writeHead(200, resp.headers);
            res.end(resp.body);
          });
        });
      }
    };

gruntFile.js

// Usage example

module.exports = function(grunt) {
  var urlRewrite = require('grunt-connect-rewrite');

  // Project configuration.
  grunt.initConfig({
    connect: {
      server: {
        options: {
          port: 3000,
          base: '.',
		      middleware: function(connect, options) {
            // Return array of whatever middlewares you want
            return [
              // redirect all urls to index.html in '.' folder
              urlRewrite(),
 
              // Serve static files.
              connect.static(options.base),
 
              // Make empty directories browsable.
              connect.directory(options.base)
            ];
          }
	      }
      }
	  } 
  });
  
  grunt.loadNpmTasks('grunt-contrib-connect');
  
  grunt.registerTask('default', ['connect']);

};