Break up parseURL middleware

server/middleware/validatePackageName.js

@@ -0,0 +1,20 @@
+const validateNpmPackageName = require("validate-npm-package-name");
+
+/**
+ * Reject requests for invalid npm package names.
+ */
+function validatePackageName(req, res, next) {
+  const nameErrors = validateNpmPackageName(req.packageName).errors;
+
+  if (nameErrors) {
+    const reason = nameErrors.join(", ");
+    return res
+      .status(403)
+      .type("text")
+      .send(`Invalid package name "${req.packageName}" (${reason})`);
+  }
+
+  next();
+}
+
+module.exports = validatePackageName;