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background.js
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background.js
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/*
* 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 https://mozilla.org/MPL/2.0/.
*/
function cleanup(doc) {
// Parent domain of tracking links (e.g. foo.${domain}) and URL parameter we want to get
const domain = 'safelinks.protection.outlook.com', param = 'url';
////// Fix HTML links
// Match links to safelinks.protection.outlook.com and change them.
for (let link of doc.querySelectorAll(`a[href*="${domain}"]`)) {
const trackURL = link.href;
try {
// Extract and decode url= parameter
const cleanURL = new URL(trackURL).searchParams.get(param);
// Validate it’s a legit URL and use that as link target
link.href = new URL(cleanURL).toString();
} catch (error) {
// Could be just mentioning the safelinks service and not really a tracked link
console.warn(`Failed getting clean URL for "${trackURL}": ${error.message}`)
continue;
}
// Replace link text if it matches the tracked link
link.textContent = link.textContent.replaceAll(trackURL, link.href);
}
////// Now fix plain-text emails too.
// X-path query for all text nodes containing the incriminated domain as text
let query = document.evaluate(
`//text()[contains(., "${domain}")]`, document.body, null,
XPathResult. UNORDERED_NODE_ITERATOR_TYPE, null
);
// Make a regexp that matches the tracked links completely - don’t attempt to parse in regexp
const munged = new RegExp(
`https://[a-z0-9.]*${domain.replaceAll('.', '\\.')}/[a-zA-Z0-9-._~:/?#[\\]@%!$&'()*+,;=]*`,
'ig'
)
for (let node = query.iterateNext(); node !== null; node = query.iterateNext()) {
// Same as for HTML but replace in textContent directly
node.textContent = node.textContent.replaceAll(munged, (trackURL) => {
try {
const cleanURL = new URL(trackURL).searchParams.get(param);
return new URL(cleanURL).toString();
} catch(error) {
console.warn(`Failed getting clean URL for text "${trackURL}": ${error.message}`)
return trackURL;
}
});
}
}
document.addEventListener('DOMContentLoaded', () => {
// inject function code and call it on document object on displayed and composed messages
messenger.messageDisplayScripts.register({
js: [{ code: `(${cleanup.toString()})(document);` }],
});
messenger.composeScripts.register({
js: [{ code: `(${cleanup.toString()})(document);` }],
});
});