@beignet/core/dist/server/hooks/cors.js

Core framework primitives for Beignet

/**
 * CORS hook utilities for @beignet/core/server
 */
import { BEIGNET_ERROR_OWNER_HEADER } from "../../contracts/types.js";
const DEFAULT_CORS = {
    origins: "*",
    methods: ["GET", "POST", "PUT", "PATCH", "DELETE", "OPTIONS"],
    headers: ["Content-Type", "Authorization"],
    exposedHeaders: [],
    credentials: false,
};
function resolveCorsConfig(config) {
    const resolved = {
        origins: config.origins ?? DEFAULT_CORS.origins,
        methods: config.methods ?? DEFAULT_CORS.methods,
        headers: config.headers ?? DEFAULT_CORS.headers,
        exposedHeaders: config.exposedHeaders ?? DEFAULT_CORS.exposedHeaders,
        credentials: config.credentials ?? DEFAULT_CORS.credentials,
    };
    if (resolved.credentials &&
        (resolved.origins === "*" ||
            (Array.isArray(resolved.origins) && resolved.origins.includes("*")))) {
        throw new Error('Credentialed CORS cannot use a wildcard origin. Use origins: ["https://app.example.com"] with credentials: true.');
    }
    return resolved;
}
function appendVaryOrigin(headers) {
    const varyKey = Object.keys(headers).find((key) => key.toLowerCase() === "vary") ?? "Vary";
    const currentValue = headers[varyKey];
    const current = typeof currentValue === "string" ? currentValue : currentValue?.join(", ");
    const values = current?.split(",").map((value) => value.trim().toLowerCase());
    if (values?.includes("origin"))
        return;
    headers[varyKey] = current ? `${current}, Origin` : "Origin";
}
function appendCommaSeparatedHeader(headers, name, appended) {
    const key = Object.keys(headers).find((candidate) => candidate.toLowerCase() === name.toLowerCase()) ?? name;
    const existing = headers[key];
    const values = [
        ...(typeof existing === "string"
            ? existing.split(",")
            : (existing ?? []).flatMap((value) => value.split(","))),
        ...appended,
    ]
        .map((value) => value.trim())
        .filter(Boolean);
    const seen = new Set();
    const unique = values.filter((value) => {
        const normalized = value.toLowerCase();
        if (seen.has(normalized))
            return false;
        seen.add(normalized);
        return true;
    });
    headers[key] = unique.join(", ");
}
/**
 * Apply CORS response headers to a mutable header record.
 *
 * Credentialed CORS rejects wildcard origins. Use an explicit origin allow-list
 * when cookies or authorization headers are allowed cross-origin.
 */
export function applyCorsHeaders(headers, req, corsConfig) {
    const { origins, methods, headers: allowedHeaders, exposedHeaders, credentials, } = resolveCorsConfig(corsConfig);
    if (origins === "*") {
        headers["Access-Control-Allow-Origin"] = "*";
    }
    else if (Array.isArray(origins)) {
        const requestOrigin = req.headers.get("Origin");
        if (requestOrigin && origins.includes(requestOrigin)) {
            headers["Access-Control-Allow-Origin"] = requestOrigin;
            appendVaryOrigin(headers);
        }
    }
    headers["Access-Control-Allow-Methods"] = methods.join(", ");
    headers["Access-Control-Allow-Headers"] = allowedHeaders.join(", ");
    appendCommaSeparatedHeader(headers, "Access-Control-Expose-Headers", [
        BEIGNET_ERROR_OWNER_HEADER,
        ...exposedHeaders,
    ]);
    if (credentials) {
        headers["Access-Control-Allow-Credentials"] = "true";
    }
}
/**
 * Create CORS hooks for preflight and regular responses.
 *
 * CORS preflight requests short-circuit with a 204 response. Explicit
 * `OPTIONS` routes without `Access-Control-Request-Method` continue through the
 * normal route pipeline. All responses are decorated in `beforeSend`.
 */
export function createCorsHooks(config) {
    const corsConfig = resolveCorsConfig(config);
    return {
        name: "cors",
        onRequest: ({ req }) => {
            if (req.method !== "OPTIONS" ||
                !req.headers.get("Origin") ||
                !req.headers.get("Access-Control-Request-Method")) {
                return undefined;
            }
            const headers = {};
            applyCorsHeaders(headers, req, corsConfig);
            return {
                status: 204,
                headers,
                body: null,
            };
        },
        beforeSend: ({ req, response }) => {
            const headers = { ...(response.headers ?? {}) };
            applyCorsHeaders(headers, req, corsConfig);
            return {
                ...response,
                headers,
            };
        },
    };
}
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