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/**
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* Myext main content script run in all frames
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*
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* Copyright (C) 2021 Wojtek Kosior
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* Redistribution terms are gathered in the `copyright' file.
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*/
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/*
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* IMPORTS_START
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* IMPORT handle_page_actions
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* IMPORT url_item
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* IMPORT url_extract_target
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* IMPORT gen_unique
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* IMPORT csp_rule
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* IMPORT is_privileged_url
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* IMPORT sanitize_attributes
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* IMPORT script_suppressor
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* IMPORT is_chrome
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* IMPORT is_mozilla
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* IMPORT start_activity_info_server
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* IMPORTS_END
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*/
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/*
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* Due to some technical limitations the chosen method of whitelisting sites
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* is to smuggle whitelist indicator in page's url as a "magical" string
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* after '#'. Right now this is not needed in HTTP(s) pages where native
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* script blocking happens through CSP header injection but is needed for
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* protocols like ftp:// and file://.
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*
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* The code that actually injects the magical string into ftp:// and file://
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* urls has not yet been added to the extension.
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*/
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let url = url_item(document.URL);
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let unique = gen_unique(url);
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const suppressor = script_suppressor(unique);
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function is_http()
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{
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return !!/^https?:\/\//i.exec(document.URL);
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}
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function is_whitelisted()
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{
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const parsed_url = url_extract_target(document.URL);
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if (parsed_url.target !== undefined &&
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parsed_url.target === '#' + unique) {
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if (parsed_url.target2 !== undefined)
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window.location.href = parsed_url.base_url + parsed_url.target2;
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else
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history.replaceState(null, "", parsed_url.base_url);
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return true;
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}
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return false;
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}
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function handle_mutation(mutations, observer)
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{
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if (document.readyState === 'complete') {
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console.log("mutation handling complete");
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observer.disconnect();
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return;
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}
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for (const mutation of mutations) {
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for (const node of mutation.addedNodes)
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block_node(node);
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}
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}
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function block_nodes_recursively(node)
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{
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block_node(node);
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for (const child of node.children)
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block_nodes_recursively(child);
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}
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function block_node(node)
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{
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/*
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* Modifying <script> element doesn't always prevent its
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* execution in some Mozilla browsers. Additional blocking
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* through CSP meta tag injection is required.
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*/
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if (node.tagName === "SCRIPT") {
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block_script(node);
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return;
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}
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sanitize_attributes(node);
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if (node.tagName === "HEAD")
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inject_csp(node);
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}
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function block_script(node)
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{
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/*
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* Disabling scripts this way allows them to still be relatively
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* easily accessed in case they contain some useful data.
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*/
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if (node.hasAttribute("type"))
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node.setAttribute("blocked-type", node.getAttribute("type"));
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node.setAttribute("type", "application/json");
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}
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function inject_csp(head)
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{
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console.log('injecting CSP');
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let meta = document.createElement("meta");
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meta.setAttribute("http-equiv", "Content-Security-Policy");
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meta.setAttribute("content", csp_rule(unique));
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if (head.firstElementChild === null)
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head.appendChild(meta);
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else
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head.insertBefore(meta, head.firstElementChild);
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}
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if (!is_privileged_url(document.URL)) {
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start_activity_info_server();
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handle_page_actions(unique);
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if (is_http()) {
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/* rely on CSP injected through webRequest */
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} else if (is_whitelisted()) {
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/* do not block scripts at all */
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} else {
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block_nodes_recursively(document.documentElement);
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if (is_chrome) {
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var observer = new MutationObserver(handle_mutation);
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observer.observe(document.documentElement, {
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attributes: true,
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childList: true,
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subtree: true
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});
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}
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if (is_mozilla)
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addEventListener('beforescriptexecute', suppressor, true);
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}
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}
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