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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)$)/;
43
44/**
45 * What is costly to answer for a signed-out visitor, or must not be flooded:
46 * a repository's archives, a run's page, log downloads and artifacts,
47 * search, and the form that reports a vulnerability to a repository's
48 * maintainers privately, which takes no account. A running job's live log
49 * (`actions/jobs/:job/log`, a small read the page makes about once a
50 * second) counts as a page: with the run's page refreshing beside it, it
51 * would use up this limit in half a minute.
52 */
53const HEAVY =
54 /^\/(?:search(?:\.data)?$|[^/]+\/[^/]+\/(?:archive\/|actions\/runs\/[^/]+(?:\.data|\/logs\.zip|\/artifacts\/[^/]+)?$|actions\/jobs\/[^/]+\/log\.txt$|security\/report(?:\.data)?$))/;
55
56export function unlimited(pathname: string): boolean {
57 return UNLIMITED.test(pathname);
58}
59
60export function heavy(pathname: string): boolean {
61 return HEAVY.test(pathname);
62}
63
64/** The signed token of an archive download link (`archive/<ref>.zip|.tar.gz?token=`), or null. */
65export function archiveLink(pathname: string, url: string): string | null {
66 if (!/^\/[^/]+\/[^/]+\/archive\/.+\.(?:zip|tar\.gz)$/.test(pathname)) return null;
67 try {
68 return new URL(url).searchParams.get("token") || null;
69 } catch {
70 return null;
71 }
72}
73
74/** The session cookie's value, or null when signed out. */
75export function sessionCookie(cookie: string | null): string | null {
76 const match = /(?:^|;\s*)g1t_session=([^;]+)/.exec(cookie ?? "");
77 return match?.[1] ?? null;
78}
79
80const GIT_MESSAGE_ANONYMOUS =
81 "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";
82const GIT_MESSAGE_SIGNED = "Too many git requests with these credentials. Wait a minute and try again: https://docs.g1t.sh/reference/rate-limits/\n";
83const PAGE_MESSAGE = "Too many requests from your network. Wait a minute and try again.\n";
84const TOKEN_PAGE_MESSAGE = "Too many requests with this access token. Wait a minute and try again: https://docs.g1t.sh/reference/rate-limits/\n";
85
86/**
87 * The 429 for a git request past its limit, or null to go on. Git shows a
88 * plain-text answer's body to the person running it.
89 */
90export async function gitLimited(env: FrontDoorLimits, request: Request): Promise<Response | null> {
91 const credentials = request.headers.get("authorization");
92 if (credentials) {
93 const verdict = await checkLimit(env.GIT_SIGNED_LIMIT, await secretKey("git", credentials));
94 return verdict === "limited" ? tooManyRequests(GIT_MESSAGE_SIGNED) : null;
95 }
96 const verdict = await checkLimit(env.GIT_ANONYMOUS_LIMIT, `ip:${clientAddress(request)}`);
97 return verdict === "limited" ? tooManyRequests(GIT_MESSAGE_ANONYMOUS) : null;
98}
99
100/**
101 * The token in a page request's `Authorization: Bearer` header, or null
102 * (app/lib/website-token.ts). Not checked here either.
103 */
104export function websiteToken(authorization: string | null): string | null {
105 return /^\s*bearer\s+(\S+)\s*$/i.exec(authorization ?? "")?.[1] ?? null;
106}
107
108/** The 429 for a page or data request past its limit, or null to go on. */
109export async function pageLimited(env: FrontDoorLimits, request: Request, pathname: string): Promise<Response | null> {
110 if (unlimited(pathname)) return null;
111 const address = `ip:${clientAddress(request)}`;
112 const token = websiteToken(request.headers.get("authorization"));
113 const session = sessionCookie(request.headers.get("cookie"));
114 const checks: Promise<string>[] = [checkLimit(env.WEB_ADDRESS_LIMIT, address)];
115 if (token) {
116 // A token on the website: per token, as the API counts it.
117 checks.push(secretKey("token", token).then((key) => checkLimit(env.WEB_TOKEN_LIMIT, key)));
118 } else if (session) {
119 checks.push(secretKey("session", session).then((key) => checkLimit(env.WEB_SESSION_LIMIT, key)));
120 } else if (archiveLink(pathname, request.url)) {
121 // A signed archive link (`GET /repos/{owner}/{repo}/tarball/{ref}` made
122 // it for one commit, for 10 minutes) counts per link, as a token does:
123 // many jobs behind one address fall back to tarballs at once.
124 checks.push(secretKey("archive", archiveLink(pathname, request.url)!).then((key) => checkLimit(env.WEB_TOKEN_LIMIT, key)));
125 } else {
126 checks.push(checkLimit(env.WEB_ANONYMOUS_LIMIT, address));
127 if (heavy(pathname)) checks.push(checkLimit(env.WEB_HEAVY_LIMIT, address));
128 }
129 const verdicts = await Promise.all(checks);
130 if (!verdicts.includes("limited")) return null;
131 if (token && verdicts[1] === "limited") return tooManyRequests(TOKEN_PAGE_MESSAGE);
132 return tooManyRequests(token || session ? PAGE_MESSAGE : `${PAGE_MESSAGE.trimEnd()} Signed-in accounts have a higher limit.\n`);
133}
134
135/**
136 * The 429 for a repository file on the usercontent origin past its limit,
137 * or null to go on. Nothing there is signed in (it never sees the session
138 * cookie), so a file counts as a signed-out page from its address. Avatars,
139 * custom emoji and production images are answered from cache and are not
140 * limited.
141 */
142export async function usercontentLimited(env: FrontDoorLimits, request: Request, path: string): Promise<Response | null> {
143 if (path.startsWith("/avatars/") || path.startsWith("/emoji/") || path.startsWith("/production-images/")) return null;
144 const verdict = await checkLimit(env.WEB_ANONYMOUS_LIMIT, `ip:${clientAddress(request)}`);
145 return verdict === "limited" ? tooManyRequests(PAGE_MESSAGE) : null;
146}