fix: remove invalid character for XML feed; fix #537

packages/saber-plugin-feed/lib/index.js

@@ -1,6 +1,6 @@
 const path = require('path')
 const { Feed } = require('feed')
-const { getFeedPath, resolveURL } = require('./utils')
+const { getFeedPath, resolveURL, removeXMLInvalidChars } = require('./utils')
 
 const ID = 'generate-feed'
 
@@ -69,7 +69,7 @@ exports.apply = (api, options = {}) => {
           // Strip HTML tags in excerpt and use it as description (a.k.a. summary)
           description:
             page.excerpt && page.excerpt.replace(/<(?:.|\n)*?>/gm, ''),
-          content,
+          content: removeXMLInvalidChars(content),
           date: page.updatedAt,
           published: page.createdAt
         })

packages/saber-plugin-feed/lib/utils.js

@@ -26,3 +26,33 @@ exports.getFeedPath = (feedPath, defaultPath) => {
 exports.resolveURL = (base, pathname) => {
   return new URL(pathname, base).href
 }
+
+/**
+ * Removes XML-invalid characters from a string.
+ * @param {string} string - a string potentially containing XML-invalid characters, such as non-UTF8 characters, STX, EOX and so on.
+ * @param {boolean} removeDiscouragedChars - a string potentially containing XML-invalid characters, such as non-UTF8 characters, STX, EOX and so on.
+ * @return : a sanitized string without all the XML-invalid characters.
+ */
+exports.removeXMLInvalidChars = (string, removeDiscouragedChars = true) => {
+  // remove everything forbidden by XML 1.0 specifications, plus the unicode replacement character U+FFFD
+  var regex = /((?:[\0-\x08\x0B\f\x0E-\x1F\uFFFD\uFFFE\uFFFF]|[\uD800-\uDBFF](?![\uDC00-\uDFFF])|(?:[^\uD800-\uDBFF]|^)[\uDC00-\uDFFF]))/g
+  string = string.replace(regex, '')
+
+  if (removeDiscouragedChars) {
+    // remove everything not suggested by XML 1.0 specifications
+    regex = new RegExp(
+      '([\\x7F-\\x84]|[\\x86-\\x9F]|[\\uFDD0-\\uFDEF]|(?:\\uD83F[\\uDFFE\\uDFFF])|(?:\\uD87F[\\uDF' +
+        'FE\\uDFFF])|(?:\\uD8BF[\\uDFFE\\uDFFF])|(?:\\uD8FF[\\uDFFE\\uDFFF])|(?:\\uD93F[\\uDFFE\\uD' +
+        'FFF])|(?:\\uD97F[\\uDFFE\\uDFFF])|(?:\\uD9BF[\\uDFFE\\uDFFF])|(?:\\uD9FF[\\uDFFE\\uDFFF])' +
+        '|(?:\\uDA3F[\\uDFFE\\uDFFF])|(?:\\uDA7F[\\uDFFE\\uDFFF])|(?:\\uDABF[\\uDFFE\\uDFFF])|(?:\\' +
+        'uDAFF[\\uDFFE\\uDFFF])|(?:\\uDB3F[\\uDFFE\\uDFFF])|(?:\\uDB7F[\\uDFFE\\uDFFF])|(?:\\uDBBF' +
+        '[\\uDFFE\\uDFFF])|(?:\\uDBFF[\\uDFFE\\uDFFF])(?:[\\0-\\t\\x0B\\f\\x0E-\\u2027\\u202A-\\uD7FF\\' +
+        'uE000-\\uFFFF]|[\\uD800-\\uDBFF][\\uDC00-\\uDFFF]|[\\uD800-\\uDBFF](?![\\uDC00-\\uDFFF])|' +
+        '(?:[^\\uD800-\\uDBFF]|^)[\\uDC00-\\uDFFF]))',
+      'g'
+    )
+    string = string.replace(regex, '')
+  }
+
+  return string
+}