sample files for https://github.com/steve-jansen/json-proxy/issues/19

test.js

var express = require('express'),
    proxy = require('./lib/proxy');

var app = express();

app.configure(function() {
  app.use(express.favicon(false));
  app.use(express.logger('dev'));
  app.use(proxy.initialize({
    proxy: {
      forward: {
        '/(.*)': 'http://nylen.tv/digest.php?$1'
      },
      headers: {
        /**
         * callback to perform digest authentication tranparently
         * @param  {[type]} req the http-proxy incoming request
         */
        'Authorization':  function(req) {
          console.log('Authorization:', process.env.JSON_PROXY_DIGEST_TOKEN)
          return process.env.JSON_PROXY_DIGEST_TOKEN;
        }
      }
    }
  }));
  app.use(express.static(__dirname));
});

app.listen(5000);
console.log('listening on http://localhost:5000');

test.sh

#!/bin/bash
# use curl to perform the digest auth
# steal the auth header from the 2nd request
export JSON_PROXY_DIGEST_TOKEN=`curl -s -v --digest -u "admin:mypa" http://nylen.tv/digest.php 2>&1 | grep Authorization | cut -b 18-`
node test.js

WRONG.js

var express = require('express'),
    proxy = require('./lib/proxy');

var app = express();

app.configure(function() {
  app.use(express.favicon(false));
  app.use(express.logger('dev'));
  app.use(proxy.initialize({
    proxy: {
      forward: {
        '/digest/(.*)': 'http://nylen.tv/digest.php?$1'
      },
      headers: {
        /**
         * callback to perform digest authentication tranparently
         * @param  {[type]} req the http-proxy incoming request
         */
        'Authorization':  function(req) {
          var token = process.env.JSON_PROXY_DIGEST_TOKEN,
              request;

          if (typeof(token) === 'string' && token.length > 0) {
            return token;
          }

          /* the request module is not installed by json-proxy - verify it's available */
          try {
            request = require('request');
          } catch (e) {
            throw new Error('request module not installed - please `npm install request`');
          }

          var r = request({
            /* Credit to @nylen for this demo! https://github.com/mikeal/request/issues/580 */
            uri  : 'http://nylen.tv/digest.php',
            method: 'HEAD',
            auth : {
                user : 'admin',
                pass : 'mypass',
                sendImmediately : false
              }
            }, function(err, res, body) {
              if (err) {
                console.error('Error performing digest authentication:', err.message);
                return;
              } else if (res.statusCode !== 200) {
                console.error('Error response performing digest authentication:',  res.statusCode);
                return;
              }

              // TOTAL HACK: cache the digest response using an env variable
              //             this is awful, and json-proxy should be refactored to
              //             support a callback in this function if enough people
              //             ask for proper digest auth support
              process.env.JSON_PROXY_DIGEST_TOKEN =  r.req._headers.authorization;
              console.log('Created digest authentication header');
              console.log(process.env.JSON_PROXY_DIGEST_TOKEN)
          });
        }
      }
    }
  }));
  app.use(express.static(__dirname));
});

app.listen(5000);
console.log('listening on http://localhost:5000');