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Code Issues Releases Wiki Activity

Use more early returns

pull/27326/head
Travis Ralston 2024-04-23 14:02:17 -06:00
parent 2ad00c03dd
commit 0951fe7ef0
1 changed files with 62 additions and 50 deletions
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112
src/serviceworker/index.ts
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@ -54,59 +54,71 @@ self.addEventListener("fetch", (event: FetchEvent) => {
// We only intercept v3 download and thumbnail requests as presumably everything else is deliberate.
// For example, `/_matrix/media/unstable` or `/_matrix/media/v3/preview_url` are something well within
// the control of the application, and appear to be choices made at a higher level than us.
if (url.includes("/_matrix/media/v3/download") || url.includes("/_matrix/media/v3/thumbnail")) {
// We need to call respondWith synchronously, otherwise we may never execute properly. This means
// later on we need to proxy the request through if it turns out the server doesn't support authentication.
event.respondWith(
(async (): Promise<Response> => {
let fetchConfig: { headers?: { [key: string]: string } } = {};
try {
// Figure out which homeserver we're communicating with
const csApi = url.substring(0, url.indexOf("/_matrix/media/v3"));
// Add jitter to reduce request spam, particularly to `/versions` on initial page load
await new Promise<void>((resolve) => setTimeout(() => resolve(), Math.random() * 10));
// Locate our access token, and populate the fetchConfig with the authentication header.
// @ts-expect-error - service worker types are not available. See 'fetch' event handler.
const client = await self.clients.get(event.clientId);
const accessToken = await getAccessToken(client);
if (accessToken) {
fetchConfig = {
headers: {
Authorization: `Bearer ${accessToken}`,
},
};
}
// Update or populate the server support map using a (usually) authenticated `/versions` call.
if (!serverSupportMap[csApi] || serverSupportMap[csApi].cacheExpires <= new Date().getTime()) {
const versions = await (await fetch(`${csApi}/_matrix/client/versions`, fetchConfig)).json();
serverSupportMap[csApi] = {
supportsMSC3916: Boolean(versions?.unstable_features?.["org.matrix.msc3916"]),
cacheExpires: new Date().getTime() + 2 * 60 * 60 * 1000, // 2 hours from now
};
}
// If we have server support (and a means of authentication), rewrite the URL to use MSC3916 endpoints.
if (serverSupportMap[csApi].supportsMSC3916 && accessToken) {
// Currently unstable only.
// TODO: Support stable endpoints when available.
url = url.replace(/\/media\/v3\/(.*)\//, "/client/unstable/org.matrix.msc3916/media/$1/");
} // else by default we make no changes
} catch (err) {
console.error("SW: Error in request rewrite.", err);
}
// Add authentication and send the request. We add authentication even if MSC3916 endpoints aren't
// being used to ensure patches like this work:
// https://github.com/matrix-org/synapse/commit/2390b66bf0ec3ff5ffb0c7333f3c9b239eeb92bb
return fetch(url, fetchConfig);
})(),
);
if (!url.includes("/_matrix/media/v3/download") && !url.includes("/_matrix/media/v3/thumbnail")) {
return; // not a URL we care about
}
// We need to call respondWith synchronously, otherwise we may never execute properly. This means
// later on we need to proxy the request through if it turns out the server doesn't support authentication.
event.respondWith(
(async (): Promise<Response> => {
let accessToken: string | undefined;
try {
// Figure out which homeserver we're communicating with
const csApi = url.substring(0, url.indexOf("/_matrix/media/v3"));
// Add jitter to reduce request spam, particularly to `/versions` on initial page load
await new Promise<void>((resolve) => setTimeout(() => resolve(), Math.random() * 10));
// Locate our access token, and populate the fetchConfig with the authentication header.
// @ts-expect-error - service worker types are not available. See 'fetch' event handler.
const client = await self.clients.get(event.clientId);
accessToken = await getAccessToken(client);
// Update or populate the server support map using a (usually) authenticated `/versions` call.
await tryUpdateServerSupportMap(csApi, accessToken);
// If we have server support (and a means of authentication), rewrite the URL to use MSC3916 endpoints.
if (serverSupportMap[csApi].supportsMSC3916 && accessToken) {
// Currently unstable only.
// TODO: Support stable endpoints when available.
url = url.replace(/\/media\/v3\/(.*)\//, "/client/unstable/org.matrix.msc3916/media/$1/");
} // else by default we make no changes
} catch (err) {
console.error("SW: Error in request rewrite.", err);
}
// Add authentication and send the request. We add authentication even if MSC3916 endpoints aren't
// being used to ensure patches like this work:
// https://github.com/matrix-org/synapse/commit/2390b66bf0ec3ff5ffb0c7333f3c9b239eeb92bb
const config = !accessToken ? undefined : {
headers: {
Authorization: `Bearer ${accessToken}`,
},
};
return fetch(url, config);
})(),
);
});
async function tryUpdateServerSupportMap(clientApiUrl: string, accessToken?: string): Promise<void> {
// only update if we don't know about it, or if the data is stale
if (serverSupportMap[clientApiUrl]?.cacheExpires > new Date().getTime()) {
return; // up to date
}
const versions = await (await fetch(`${clientApiUrl}/_matrix/client/versions`, {
headers: {
Authorization: `Bearer ${accessToken}`,
},
})).json();
serverSupportMap[clientApiUrl] = {
supportsMSC3916: Boolean(versions?.unstable_features?.["org.matrix.msc3916"]),
cacheExpires: new Date().getTime() + 2 * 60 * 60 * 1000, // 2 hours from now
};
}
// Ideally we'd use the `Client` interface for `client`, but since it's not available (see 'fetch' listener), we use
// unknown for now and force-cast it to something close enough later.
async function getAccessToken(client: unknown): Promise<string | undefined> {