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[CRX] Detect availability of DNR responseHeaders before use

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Critical fix for old but recent Chrome versions; all requests are
otherwise redirected to the viewer.
This commit is contained in:
Rob Wu 2024-09-09 14:26:26 +02:00
parent a1b45d6e69
commit 9705169371
1 changed files with 53 additions and 4 deletions
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57
extensions/chromium/pdfHandler.js
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@ -198,19 +198,68 @@ async function registerPdfRedirectRule() {
rule.priority = addRules.length - i;
}
try {
await chrome.declarativeNetRequest.updateDynamicRules({ addRules });
// Note: condition.responseHeaders is only supported in Chrome 128+, but
// does not trigger errors in Chrome 123 - 127 as explained at:
// https://github.com/w3c/webextensions/issues/638#issuecomment-2181124486
//
// We do not bother with detecting that because we fall back to catching
// PDF documents via maybeRenderPdfDoc in contentscript.js.
// We need to detect this and avoid registering rules, because otherwise all
// requests are redirected to the viewer instead of just PDF requests,
// because Chrome accepts rules while ignoring the responseHeaders condition
// - also reported at https://crbug.com/347186592
if (!(await isHeaderConditionSupported())) {
throw new Error("DNR responseHeaders condition is not supported.");
}
await chrome.declarativeNetRequest.updateDynamicRules({ addRules });
} catch (e) {
// When we do not register DNR rules for any reason, fall back to catching
// PDF documents via maybeRenderPdfDoc in contentscript.js.
console.error("Failed to register rules to redirect PDF requests.");
console.error(e);
}
}
// For the source and explanation of this logic, see
// https://github.com/w3c/webextensions/issues/638#issuecomment-2181124486
async function isHeaderConditionSupported() {
const ruleId = 123456; // Some rule ID that is not already used elsewhere.
try {
// Throws synchronously if not supported.
await chrome.declarativeNetRequest.updateSessionRules({
addRules: [
{
id: ruleId,
urlFilter: "|does_not_match_anything",
condition: { responseHeaders: [{ header: "whatever" }] },
action: { type: "block" },
},
],
});
} catch {
return false; // responseHeaders condition not supported.
}
// Chrome may recognize the properties but have the implementation behind a
// flag. When the implementation is disabled, validation is skipped too.
try {
await chrome.declarativeNetRequest.updateSessionRules({
removeRuleIds: [ruleId],
addRules: [
{
id: ruleId,
urlFilter: "|does_not_match_anything",
condition: { responseHeaders: [] },
action: { type: "block" },
},
],
});
return false; // Validation skipped = feature disabled.
} catch {
return true; // Validation worked = feature enabled.
} finally {
await chrome.declarativeNetRequest.updateSessionRules({
removeRuleIds: [ruleId],
});
}
}
function getViewerURL(pdf_url) {
// |pdf_url| may contain a fragment such as "#page=2". That should be passed
// as a fragment to the viewer, not encoded in pdf_url.