1 files changed, 109 insertions, 0 deletions
diff --git a/browser/extensions/webcompat/lib/custom_functions.js b/browser/extensions/webcompat/lib/custom_functions.js
new file mode 100644
index 0000000000..97603e0424
--- /dev/null
+++ b/browser/extensions/webcompat/lib/custom_functions.js
@@ -0,0 +1,109 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+/* globals browser, module */
+
+const replaceStringInRequest = (
+  requestId,
+  inString,
+  outString,
+  inEncoding = "utf-8"
+) => {
+  const filter = browser.webRequest.filterResponseData(requestId);
+  const decoder = new TextDecoder(inEncoding);
+  const encoder = new TextEncoder();
+  const RE = new RegExp(inString, "g");
+  const carryoverLength = inString.length;
+  let carryover = "";
+
+  filter.ondata = event => {
+    const replaced = (
+      carryover + decoder.decode(event.data, { stream: true })
+    ).replace(RE, outString);
+    filter.write(encoder.encode(replaced.slice(0, -carryoverLength)));
+    carryover = replaced.slice(-carryoverLength);
+  };
+
+  filter.onstop = event => {
+    if (carryover.length) {
+      filter.write(encoder.encode(carryover));
+    }
+    filter.close();
+  };
+};
+
+const CUSTOM_FUNCTIONS = {
+  detectSwipeFix: injection => {
+    const { urls, types } = injection.data;
+    const listener = (injection.data.listener = ({ requestId }) => {
+      replaceStringInRequest(
+        requestId,
+        "preventDefault:true",
+        "preventDefault:false"
+      );
+      return {};
+    });
+    browser.webRequest.onBeforeRequest.addListener(listener, { urls, types }, [
+      "blocking",
+    ]);
+  },
+  detectSwipeFixDisable: injection => {
+    const { listener } = injection.data;
+    browser.webRequest.onBeforeRequest.removeListener(listener);
+    delete injection.data.listener;
+  },
+  noSniffFix: injection => {
+    const { urls, contentType } = injection.data;
+    const listener = (injection.data.listener = e => {
+      e.responseHeaders.push(contentType);
+      return { responseHeaders: e.responseHeaders };
+    });
+
+    browser.webRequest.onHeadersReceived.addListener(listener, { urls }, [
+      "blocking",
+      "responseHeaders",
+    ]);
+  },
+  noSniffFixDisable: injection => {
+    const { listener } = injection.data;
+    browser.webRequest.onHeadersReceived.removeListener(listener);
+    delete injection.data.listener;
+  },
+  runScriptBeforeRequest: injection => {
+    const { bug, message, request, script, types } = injection;
+    const warning = `${message} See https://bugzilla.mozilla.org/show_bug.cgi?id=${bug} for details.`;
+
+    const listener = (injection.listener = e => {
+      const { tabId, frameId } = e;
+      return browser.tabs
+        .executeScript(tabId, {
+          file: script,
+          frameId,
+          runAt: "document_start",
+        })
+        .then(() => {
+          browser.tabs.executeScript(tabId, {
+            code: `console.warn(${JSON.stringify(warning)})`,
+            runAt: "document_start",
+          });
+        })
+        .catch(_ => {});
+    });
+
+    browser.webRequest.onBeforeRequest.addListener(
+      listener,
+      { urls: request, types: types || ["script"] },
+      ["blocking"]
+    );
+  },
+  runScriptBeforeRequestDisable: injection => {
+    const { listener } = injection;
+    browser.webRequest.onBeforeRequest.removeListener(listener);
+    delete injection.data.listener;
+  },
+};
+
+module.exports = CUSTOM_FUNCTIONS;