refactor into files

lib/HeaderHostTransformer.js

@@ -0,0 +1,39 @@
+var stream = require('stream');
+var util = require('util');
+
+var Transform = stream.Transform;
+
+var HeaderHostTransformer = function(opts) {
+    if (!(this instanceof HeaderHostTransformer)) {
+        return new HeaderHostTransformer(opts);
+    }
+
+    opts = opts || {}
+    Transform.call(this, opts);
+
+    var self = this;
+    self.host = opts.host || 'localhost';
+    self.replaced = false;
+}
+util.inherits(HeaderHostTransformer, Transform);
+
+HeaderHostTransformer.prototype._transform = function (chunk, enc, cb) {
+    var self = this;
+    chunk = chunk.toString();
+
+    // after replacing the first instance of the Host header
+    // we just become a regular passthrough
+    if (!self.replaced) {
+        self.push(chunk.replace(/(\r\nHost: )\S+/, function(match, $1) {
+            self.replaced = true;
+            return $1 + self.host;
+        }));
+    }
+    else {
+        self.push(chunk);
+    }
+
+    cb();
+};
+
+module.exports = HeaderHostTransformer;