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"use strict";
(() => {
let ENDPOINT_PREFIX = `https://sync-messages.invalid/${browser.extension.getURL("")}?`;
let MOZILLA = "mozSystem" in XMLHttpRequest.prototype;
if (browser.webRequest) {
if (typeof browser.runtime.onSyncMessage !== "object") {
// Background Script side
// cache of senders from early async messages to track tab ids in Firefox
let pending = new Map();
if (MOZILLA) {
// we don't care this is async, as long as it get called before the
// sync XHR (we are not interested in the response on the content side)
browser.runtime.onMessage.addListener((m, sender) => {
if (!m.___syncMessageId) return;
pending.set(m.___syncMessageId, sender);
});
}
let tabUrlCache = new Map();
let tabRemovalListener = null;
let CANCEL = {cancel: true};
let {TAB_ID_NONE} = browser.tabs;
let obrListener = request => {
let {url, tabId} = request;
let params = new URLSearchParams(url.split("?")[1]);
let msgId = params.get("id");
let msg = params.get("msg");
let documentUrl = params.get("url");
let sender;
if (tabId === TAB_ID_NONE) {
// Firefox sends privileged content script XHR without valid tab ids
// so we cache sender info from unprivileged XHR correlated by msgId
if (pending.has(msgId)) {
sender = pending.get(msgId);
pending.delete(msgId);
} else {
throw new Error(`sendSyncMessage: cannot correlate sender info for ${msgId}.`);
}
} else {
let {frameAncestors, frameId} = request;
let isTop = frameId === 0 || !!params.get("top");
let tabUrl = frameAncestors && frameAncestors.length
&& frameAncestors[frameAncestors.length - 1].url;
if (!tabUrl) {
if (isTop) {
tabUrlCache.set(tabId, tabUrl = documentUrl);
if (!tabRemovalListener) {
browser.tabs.onRemoved.addListener(tabRemovalListener = tab => {
tabUrlCache.delete(tab.id);
});
}
} else {
tabUrl = tabUrlCache.get(tabId);
}
}
sender = {
tab: {
id: tabId,
url: tabUrl
},
frameId,
url: documentUrl,
timeStamp: Date.now()
};
}
if (!(msg !== null && sender)) {
return CANCEL;
}
// Just like in the async runtime.sendMessage() API,
// we process the listeners in order until we find a not undefined
// result, then we return it (or undefined if none returns anything).
let result;
for (let l of listeners) {
try {
if ((result = l(JSON.parse(msg), sender)) !== undefined) break;
} catch (e) {
console.error(e, "Processing message %o from %o", msg, sender);
}
}
return {
redirectUrl: `data:application/json,${JSON.stringify(result)}`
};
};
let listeners = new Set();
browser.runtime.onSyncMessage = {
ENDPOINT_PREFIX,
addListener(l) {
listeners.add(l);
if (listeners.size === 1) {
browser.webRequest.onBeforeRequest.addListener(obrListener,
{urls: [`${ENDPOINT_PREFIX}*`],
types: ["xmlhttprequest"]},
["blocking"]
);
}
},
removeListener(l) {
listeners.remove(l);
if (listeners.size === 0) {
browser.webRequest.onBeforeRequest.removeListener(obrListener);
}
},
hasListener(l) {
return listeners.has(l);
}
};
}
} else if (typeof browser.runtime.sendSyncMessage !== "function") {
// Content Script side
if (typeof uuid !== "function") {
let uuid = () => (Math.random() * Date.now()).toString(16);
}
let docUrl = document.URL;
browser.runtime.sendSyncMessage = msg => {
let msgId = `${uuid()},${docUrl}`;
let url = `${ENDPOINT_PREFIX}id=${encodeURIComponent(msgId)}` +
`&url=${encodeURIComponent(docUrl)}`;
if (window.top === window) {
// we add top URL information because Chromium doesn't know anything
// about frameAncestors
url += "&top=true";
}
if (MOZILLA) {
// on Firefox we first need to send an async message telling the
// background script about the tab ID, which does not get sent
// with "privileged" XHR
browser.runtime.sendMessage({___syncMessageId: msgId});
}
// adding the payload
url += `&msg=${encodeURIComponent(JSON.stringify(msg))}`;
try {
// then we send the payload using a privileged XHR, which is not subject
// to CORS but unfortunately doesn't carry any tab id except on Chromium
let r = new XMLHttpRequest();
r.open("GET", url, false);
r.send(null);
return JSON.parse(r.responseText);
} catch(e) {
console.error(`syncMessage error in ${document.URL}: ${e.message}`);
}
return null;
};
}
})();
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