Break middleware out into separate files

server/middleware/parseURL.js

@@ -0,0 +1,30 @@
+const { parsePackageURL } = require('./PackageUtils')
+
+/**
+ * Parse and validate the URL.
+ */
+function parseURL() {
+  return function (req, res, next) {
+    let url
+    try {
+      url = parsePackageURL(req.url)
+    } catch (error) {
+      return res.status(403).send(`Invalid URL: ${req.url}`)
+    }
+
+    if (url == null)
+      return res.status(403).send(`Invalid URL: ${req.url}`)
+
+    req.packageName = url.packageName
+    req.packageVersion = url.packageVersion
+    req.packageSpec = `${req.packageName}@${req.packageVersion}`
+    req.pathname = url.pathname
+    req.filename = url.filename
+    req.search = url.search
+    req.query = url.query
+
+    next()
+  }
+}
+
+module.exports = parseURL