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