Moving the creation of ACLChechker into a factory method

This is a solution that is used in both https://github.com/solid/node-solid-server/tree/feature/quota-ui and https://github.com/solid/node-solid-server/tree/bug/root-index-special-handling

Author: megoth

lib/acl-checker.js

@@ -5,6 +5,8 @@ const debug = require('./debug').ACL
 const HTTPError = require('./http-error')
 const aclCheck = require('@solid/acl-check')
 const { URL } = require('url')
+const { promisify } = require('util')
+const fs = require('fs')
 
 const DEFAULT_ACL_SUFFIX = '.acl'
 const ACL = rdf.Namespace('http://www.w3.org/ns/auth/acl#')
@@ -144,6 +146,49 @@ class ACLChecker {
   isAcl (resource) {
     return resource.endsWith(this.suffix)
   }
+
+  static createFromLDPAndRequest (resource, ldp, req) {
+    const trustedOrigins = ldp.getTrustedOrigins(req)
+    return new ACLChecker(resource, {
+      agentOrigin: req.get('origin'),
+      // host: req.get('host'),
+      fetch: fetchFromLdp(ldp.resourceMapper),
+      fetchGraph: (uri, options) => {
+        // first try loading from local fs
+        return ldp.getGraph(uri, options.contentType)
+        // failing that, fetch remote graph
+          .catch(() => ldp.fetchGraph(uri, options))
+      },
+      suffix: ldp.suffixAcl,
+      strictOrigin: ldp.strictOrigin,
+      trustedOrigins
+    })
+  }
+}
+
+/**
+ * Returns a fetch document handler used by the ACLChecker to fetch .acl
+ * resources up the inheritance chain.
+ * The `fetch(uri, callback)` results in the callback, with either:
+ *   - `callback(err, graph)` if any error is encountered, or
+ *   - `callback(null, graph)` with the parsed RDF graph of the fetched resource
+ * @return {Function} Returns a `fetch(uri, callback)` handler
+ */
+function fetchFromLdp (mapper) {
+  return async function fetch (url, graph = rdf.graph()) {
+    // Convert the URL into a filename
+    let path, contentType
+    try {
+      ({ path, contentType } = await mapper.mapUrlToFile({ url }))
+    } catch (err) {
+      throw new HTTPError(404, err)
+    }
+    // Read the file from disk
+    const body = await promisify(fs.readFile)(path, { 'encoding': 'utf8' })
+    // Parse the file as Turtle
+    rdf.parse(body, graph, url, contentType)
+    return graph
+  }
 }
 
 // Returns the index of the last slash before the given position

lib/handlers/allow.js

@@ -1,12 +1,8 @@
 module.exports = allow
 
-const $rdf = require('rdflib')
 const path = require('path')
 const ACL = require('../acl-checker')
 const debug = require('../debug.js').ACL
-const fs = require('fs')
-const { promisify } = require('util')
-const HTTPError = require('../http-error')
 
 function allow (mode, checkPermissionsForDirectory) {
   return async function allowHandler (req, res, next) {
@@ -48,20 +44,7 @@ function allow (mode, checkPermissionsForDirectory) {
       trustedOrigins.push(ldp.serverUri)
     }
     // Obtain and store the ACL of the requested resource
-    req.acl = new ACL(rootUrl + resourcePath, {
-      agentOrigin: req.get('origin'),
-      // host: req.get('host'),
-      fetch: fetchFromLdp(ldp.resourceMapper),
-      fetchGraph: (uri, options) => {
-        // first try loading from local fs
-        return ldp.getGraph(uri, options.contentType)
-        // failing that, fetch remote graph
-          .catch(() => ldp.fetchGraph(uri, options))
-      },
-      suffix: ldp.suffixAcl,
-      strictOrigin: ldp.strictOrigin,
-      trustedOrigins: trustedOrigins
-    })
+    req.acl = ACL.createFromLDPAndRequest(rootUrl + resourcePath, ldp, req)
 
     // Ensure the user has the required permission
     const userId = req.session.userId
@@ -74,28 +57,3 @@ function allow (mode, checkPermissionsForDirectory) {
     next(error)
   }
 }
-
-/**
- * Returns a fetch document handler used by the ACLChecker to fetch .acl
- * resources up the inheritance chain.
- * The `fetch(uri, callback)` results in the callback, with either:
- *   - `callback(err, graph)` if any error is encountered, or
- *   - `callback(null, graph)` with the parsed RDF graph of the fetched resource
- * @return {Function} Returns a `fetch(uri, callback)` handler
- */
-function fetchFromLdp (mapper) {
-  return async function fetch (url, graph = $rdf.graph()) {
-    // Convert the URL into a filename
-    let path, contentType
-    try {
-      ({ path, contentType } = await mapper.mapUrlToFile({ url }))
-    } catch (err) {
-      throw new HTTPError(404, err)
-    }
-    // Read the file from disk
-    const body = await promisify(fs.readFile)(path, {'encoding': 'utf8'})
-    // Parse the file as Turtle
-    $rdf.parse(body, graph, url, contentType)
-    return graph
-  }
-}

lib/ldp.js

@@ -464,6 +464,14 @@ class LDP {
     return ensureNotExists(this, URI.joinPaths(containerURI, filename).toString())
   }
 
+  getTrustedOrigins (req) {
+    let trustedOrigins = [this.resourceMapper.resolveUrl(req.hostname)].concat(this.trustedOrigins)
+    if (this.multiuser) {
+      trustedOrigins.push(this.serverUri)
+    }
+    return trustedOrigins
+  }
+
   static mimeTypeIsRdf (mimeType) {
     return RDF_MIME_TYPES.has(mimeType)
   }