RSSHub/lib/middleware/header.ts

import { getIp } from "@/utils/helpers";
import { MiddlewareHandler } from "hono";
import etagCalculate from "etag";
import logger from "@/utils/logger";
import { config } from "@/config";
import { Data } from "@/types";

const headers: Record<string, string> = {
    'Access-Control-Allow-Methods': 'GET',
    'Content-Type': 'application/xml; charset=utf-8',
    'Cache-Control': `public, max-age=${config.cache.routeExpire}`,
    'X-Content-Type-Options': 'nosniff',
};
if (config.nodeName) {
    headers['RSSHub-Node'] = config.nodeName;
}

function etagMatches(etag: string, ifNoneMatch: string | null) {
    return ifNoneMatch != null && ifNoneMatch.split(/,\s*/).indexOf(etag) > -1
}

const middleware: MiddlewareHandler = async (ctx, next) => {
    const ip = getIp(ctx);
    logger.info(`${ctx.req.url}, user IP: ${ip}`);

    for (const key in headers) {
        ctx.header(key, headers[key])
    }
    ctx.header('Access-Control-Allow-Origin', config.allowOrigin || new URL(ctx.req.url).host);

    await next();

    const data: Data = ctx.get('data');
    if (!data || ctx.res.headers.get('ETag')) {
        return;
    }

    const lastBuildDate = data.lastBuildDate;
    delete data.lastBuildDate;
    const etag = etagCalculate(JSON.stringify(data));

    ctx.header('ETag', etag);

    const ifNoneMatch = ctx.req.header('If-None-Match') ?? null;
    if (etagMatches(etag, ifNoneMatch)) {
        console.log('in')
        ctx.status(304);
        return ctx.body(null);
    } else {
        ctx.header('Last-Modified', lastBuildDate);
    }
};

export default middleware;