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flagon-io/g1t

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1/**
2 * The front door's rate limits (workers/app.ts), per request before it is
3 * answered. The bindings and their limits are in `RATE_LIMITS`
4 * (packages/contracts/src/rate-limits.ts); CONTRIBUTING.md, "Rate limits",
5 * says how they are kept.
6 *
7 * - Git over HTTPS: without credentials, by address; with them, by a hash
8 * of the credential, much higher. A clone is about three requests.
9 * - Pages: every request that reaches the Worker counts against a ceiling
10 * per address. Signed out, by address, with a tighter limit on what is
11 * costly to answer (archives, run pages, logs, search). Signed in, by a
12 * hash of the session cookie, higher: the session is not checked here,
13 * which would cost a call to identity, and the ceiling per address keeps
14 * made-up cookies from getting round the signed-out limit. With an
15 * access token (`Authorization: Bearer`, app/lib/website-token.ts), by a
16 * hash of the token, at the API's limit for a token; the address ceiling
17 * applies as for cookies.
18 *
19 * Static assets never reach the Worker (the assets binding answers them),
20 * and the few files it serves itself are left out here too. Every limit
21 * fails open.
22 */
23import {
24 type RateLimitBinding,
25 checkLimit,
26 clientAddress,
27 secretKey,
28 tooManyRequests,
29} from "@g1t/contracts/rate-limits";
30
31export type FrontDoorLimits = {
32 WEB_ANONYMOUS_LIMIT?: RateLimitBinding;
33 WEB_HEAVY_LIMIT?: RateLimitBinding;
34 WEB_SESSION_LIMIT?: RateLimitBinding;
35 WEB_ADDRESS_LIMIT?: RateLimitBinding;
36 WEB_TOKEN_LIMIT?: RateLimitBinding;
37 GIT_ANONYMOUS_LIMIT?: RateLimitBinding;
38 GIT_SIGNED_LIMIT?: RateLimitBinding;
39};
40
41/** Files the Worker serves that are never limited: build output, fonts, and top-level files such as robots.txt. */
42const UNLIMITED = /^\/(?:assets\/|fonts\/|favicon|[^/]+\.(?:ico|png|svg|txt|xml|webmanifest)$)/;
43
44/**
45 * What is costly to answer for a signed-out visitor, or must not be flooded:
46 * a repository's archives, a run's page, logs and artifacts, search, and
47 * the form that reports a vulnerability to a repository's maintainers
48 * privately, which takes no account.
49 */
50const HEAVY =
51 /^\/(?:search(?:\.data)?$|[^/]+\/[^/]+\/(?:archive\/|actions\/runs\/[^/]+(?:\.data|\/logs\.zip|\/artifacts\/[^/]+)?$|actions\/jobs\/[^/]+\/log|security\/report(?:\.data)?$))/;
52
53export function unlimited(pathname: string): boolean {
54 return UNLIMITED.test(pathname);
55}
56
57export function heavy(pathname: string): boolean {
58 return HEAVY.test(pathname);
59}
60
61/** The session cookie's value, or null when signed out. */
62export function sessionCookie(cookie: string | null): string | null {
63 const match = /(?:^|;\s*)g1t_session=([^;]+)/.exec(cookie ?? "");
64 return match?.[1] ?? null;
65}
66
67const GIT_MESSAGE_ANONYMOUS =
68 "Too many git requests from your network. Wait a minute and try again, or use credentials for a higher limit: https://docs.g1t.sh/reference/rate-limits/\n";
69const GIT_MESSAGE_SIGNED = "Too many git requests with these credentials. Wait a minute and try again: https://docs.g1t.sh/reference/rate-limits/\n";
70const PAGE_MESSAGE = "Too many requests from your network. Wait a minute and try again.\n";
71const TOKEN_PAGE_MESSAGE = "Too many requests with this access token. Wait a minute and try again: https://docs.g1t.sh/reference/rate-limits/\n";
72
73/**
74 * The 429 for a git request past its limit, or null to go on. Git shows a
75 * plain-text answer's body to the person running it.
76 */
77export async function gitLimited(env: FrontDoorLimits, request: Request): Promise<Response | null> {
78 const credentials = request.headers.get("authorization");
79 if (credentials) {
80 const verdict = await checkLimit(env.GIT_SIGNED_LIMIT, await secretKey("git", credentials));
81 return verdict === "limited" ? tooManyRequests(GIT_MESSAGE_SIGNED) : null;
82 }
83 const verdict = await checkLimit(env.GIT_ANONYMOUS_LIMIT, `ip:${clientAddress(request)}`);
84 return verdict === "limited" ? tooManyRequests(GIT_MESSAGE_ANONYMOUS) : null;
85}
86
87/**
88 * The token in a page request's `Authorization: Bearer` header, or null
89 * (app/lib/website-token.ts). Not checked here either.
90 */
91export function websiteToken(authorization: string | null): string | null {
92 return /^\s*bearer\s+(\S+)\s*$/i.exec(authorization ?? "")?.[1] ?? null;
93}
94
95/** The 429 for a page or data request past its limit, or null to go on. */
96export async function pageLimited(env: FrontDoorLimits, request: Request, pathname: string): Promise<Response | null> {
97 if (unlimited(pathname)) return null;
98 const address = `ip:${clientAddress(request)}`;
99 const token = websiteToken(request.headers.get("authorization"));
100 const session = sessionCookie(request.headers.get("cookie"));
101 const checks: Promise<string>[] = [checkLimit(env.WEB_ADDRESS_LIMIT, address)];
102 if (token) {
103 // A token on the website: per token, as the API counts it.
104 checks.push(secretKey("token", token).then((key) => checkLimit(env.WEB_TOKEN_LIMIT, key)));
105 } else if (session) {
106 checks.push(secretKey("session", session).then((key) => checkLimit(env.WEB_SESSION_LIMIT, key)));
107 } else {
108 checks.push(checkLimit(env.WEB_ANONYMOUS_LIMIT, address));
109 if (heavy(pathname)) checks.push(checkLimit(env.WEB_HEAVY_LIMIT, address));
110 }
111 const verdicts = await Promise.all(checks);
112 if (!verdicts.includes("limited")) return null;
113 if (token && verdicts[1] === "limited") return tooManyRequests(TOKEN_PAGE_MESSAGE);
114 return tooManyRequests(token || session ? PAGE_MESSAGE : `${PAGE_MESSAGE.trimEnd()} Signed-in accounts have a higher limit.\n`);
115}
116
117/**
118 * The 429 for a repository file on the usercontent origin past its limit,
119 * or null to go on. Nothing there is signed in (it never sees the session
120 * cookie), so a file counts as a signed-out page from its address. Avatars
121 * and custom emoji are answered from cache and are not limited.
122 */
123export async function usercontentLimited(env: FrontDoorLimits, request: Request, path: string): Promise<Response | null> {
124 if (path.startsWith("/avatars/") || path.startsWith("/emoji/")) return null;
125 const verdict = await checkLimit(env.WEB_ANONYMOUS_LIMIT, `ip:${clientAddress(request)}`);
126 return verdict === "limited" ? tooManyRequests(PAGE_MESSAGE) : null;
127}