get-uri/dist/http.js

"use strict";
var __importDefault = (this && this.__importDefault) || function (mod) {
    return (mod && mod.__esModule) ? mod : { "default": mod };
};
Object.defineProperty(exports, "__esModule", { value: true });
exports.http = void 0;
const http_1 = __importDefault(require("http"));
const https_1 = __importDefault(require("https"));
const once_1 = __importDefault(require("@tootallnate/once"));
const debug_1 = __importDefault(require("debug"));
const http_error_1 = __importDefault(require("./http-error"));
const notfound_1 = __importDefault(require("./notfound"));
const notmodified_1 = __importDefault(require("./notmodified"));
const debug = (0, debug_1.default)('get-uri:http');
/**
 * Returns a Readable stream from an "http:" URI.
 */
const http = async (url, opts = {}) => {
    debug('GET %o', url.href);
    const cache = getCache(url, opts.cache);
    // first check the previous Expires and/or Cache-Control headers
    // of a previous response if a `cache` was provided
    if (cache && isFresh(cache) && typeof cache.statusCode === 'number') {
        // check for a 3xx "redirect" status code on the previous cache
        const type = (cache.statusCode / 100) | 0;
        if (type === 3 && cache.headers.location) {
            debug('cached redirect');
            throw new Error('TODO: implement cached redirects!');
        }
        // otherwise we assume that it's the destination endpoint,
        // since there's nowhere else to redirect to
        throw new notmodified_1.default();
    }
    // 5 redirects allowed by default
    const maxRedirects = typeof opts.maxRedirects === 'number' ? opts.maxRedirects : 5;
    debug('allowing %o max redirects', maxRedirects);
    let mod;
    if (opts.http) {
        // the `https` module passed in from the "http.js" file
        mod = opts.http;
        debug('using secure `https` core module');
    }
    else {
        mod = http_1.default;
        debug('using `http` core module');
    }
    const options = { ...opts };
    // add "cache validation" headers if a `cache` was provided
    if (cache) {
        if (!options.headers) {
            options.headers = {};
        }
        const lastModified = cache.headers['last-modified'];
        if (lastModified) {
            options.headers['If-Modified-Since'] = lastModified;
            debug('added "If-Modified-Since" request header: %o', lastModified);
        }
        const etag = cache.headers.etag;
        if (etag) {
            options.headers['If-None-Match'] = etag;
            debug('added "If-None-Match" request header: %o', etag);
        }
    }
    const req = mod.get(url, options);
    const [res] = await (0, once_1.default)(req, 'response');
    const code = res.statusCode || 0;
    // assign a Date to this response for the "Cache-Control" delta calculation
    res.date = Date.now();
    res.parsed = url;
    debug('got %o response status code', code);
    // any 2xx response is a "success" code
    let type = (code / 100) | 0;
    // check for a 3xx "redirect" status code
    let location = res.headers.location;
    if (type === 3 && location) {
        if (!opts.redirects)
            opts.redirects = [];
        let redirects = opts.redirects;
        if (redirects.length < maxRedirects) {
            debug('got a "redirect" status code with Location: %o', location);
            // flush this response - we're not going to use it
            res.resume();
            // hang on to this Response object for the "redirects" Array
            redirects.push(res);
            let newUri = new URL(location, url.href);
            debug('resolved redirect URL: %o', newUri.href);
            let left = maxRedirects - redirects.length;
            debug('%o more redirects allowed after this one', left);
            // check if redirecting to a different protocol
            if (newUri.protocol !== url.protocol) {
                opts.http = newUri.protocol === 'https:' ? https_1.default : undefined;
            }
            return (0, exports.http)(newUri, opts);
        }
    }
    // if we didn't get a 2xx "success" status code, then create an Error object
    if (type !== 2) {
        res.resume();
        if (code === 304) {
            throw new notmodified_1.default();
        }
        else if (code === 404) {
            throw new notfound_1.default();
        }
        // other HTTP-level error
        throw new http_error_1.default(code);
    }
    if (opts.redirects) {
        // store a reference to the "redirects" Array on the Response object so that
        // they can be inspected during a subsequent call to GET the same URI
        res.redirects = opts.redirects;
    }
    return res;
};
exports.http = http;
/**
 * Returns `true` if the provided cache's "freshness" is valid. That is, either
 * the Cache-Control header or Expires header values are still within the allowed
 * time period.
 *
 * @return {Boolean}
 * @api private
 */
function isFresh(cache) {
    let fresh = false;
    let expires = parseInt(cache.headers.expires || '', 10);
    const cacheControl = cache.headers['cache-control'];
    if (cacheControl) {
        // for Cache-Control rules, see: http://www.mnot.net/cache_docs/#CACHE-CONTROL
        debug('Cache-Control: %o', cacheControl);
        const parts = cacheControl.split(/,\s*?\b/);
        for (let i = 0; i < parts.length; i++) {
            const part = parts[i];
            const subparts = part.split('=');
            const name = subparts[0];
            switch (name) {
                case 'max-age':
                    expires =
                        (cache.date || 0) + parseInt(subparts[1], 10) * 1000;
                    fresh = Date.now() < expires;
                    if (fresh) {
                        debug('cache is "fresh" due to previous %o Cache-Control param', part);
                    }
                    return fresh;
                case 'must-revalidate':
                    // XXX: what we supposed to do here?
                    break;
                case 'no-cache':
                case 'no-store':
                    debug('cache is "stale" due to explicit %o Cache-Control param', name);
                    return false;
                default:
                    // ignore unknown cache value
                    break;
            }
        }
    }
    else if (expires) {
        // for Expires rules, see: http://www.mnot.net/cache_docs/#EXPIRES
        debug('Expires: %o', expires);
        fresh = Date.now() < expires;
        if (fresh) {
            debug('cache is "fresh" due to previous Expires response header');
        }
        return fresh;
    }
    return false;
}
/**
 * Attempts to return a previous Response object from a previous GET call to the
 * same URI.
 *
 * @api private
 */
function getCache(url, cache) {
    if (cache) {
        if (cache.parsed && cache.parsed.href === url.href) {
            return cache;
        }
        if (cache.redirects) {
            for (let i = 0; i < cache.redirects.length; i++) {
                const c = getCache(url, cache.redirects[i]);
                if (c) {
                    return c;
                }
            }
        }
    }
    return null;
}
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