polyserve/lib/util/push.js

A simple dev server for bower components

"use strict";
/**
 * @license
 * Copyright (c) 2015 The Polymer Project Authors. All rights reserved.
 * This code may only be used under the BSD style license found at
 * http://polymer.github.io/LICENSE.txt
 * The complete set of authors may be found at
 * http://polymer.github.io/AUTHORS.txt
 * The complete set of contributors may be found at
 * http://polymer.github.io/CONTRIBUTORS.txt
 * Code distributed by Google as part of the polymer project is also
 * subject to an additional IP rights grant found at
 * http://polymer.github.io/PATENTS.txt
 */
Object.defineProperty(exports, "__esModule", { value: true });
const assert = require("assert");
const fs = require("fs");
const mime = require("mime");
const path = require("path");
/** h2 push manifest cache */
const _pushManifest = {};
/**
 * Asserts file existence for all specified files in a push-manifest
 * @param root path to root directory
 * @param manifest manifest object
 */
function assertValidManifest(root, manifest) {
    function assertExists(filename) {
        const fname = path.join(root, filename);
        try {
            // Ignore root path, since that always exists for the router
            if (filename !== '/') {
                assert(fs.existsSync(fname), `not found: ${fname}`);
            }
        }
        catch (err) {
            throw new Error(`invalid h2-push manifest: ${err}`);
        }
    }
    for (const refFile of Object.keys(manifest)) {
        assertExists(refFile);
        for (const pushFile of Object.keys(manifest[refFile])) {
            assertExists(pushFile);
        }
    }
}
/**
 * Reads a push-manifest from the specified path, or a cached version
 * of the file
 * @param root path to root directory
 * @param manifestPath path to manifest file
 * @returns the manifest
 */
function getPushManifest(root, manifestPath) {
    if (!_pushManifest[manifestPath]) {
        const data = fs.readFileSync(manifestPath);
        const manifest = JSON.parse(data.toString());
        assertValidManifest(root, manifest);
        _pushManifest[manifestPath] = manifest;
    }
    return _pushManifest[manifestPath];
}
exports.getPushManifest = getPushManifest;
/**
 * Pushes any resources for the requested file
 * @param options server options
 * @param req HTTP request
 * @param res HTTP response
 */
function pushResources(options, req, res) {
    if (res.push && options.protocol === 'h2' && options.pushManifestPath &&
        !req.get('x-is-push')) {
        // TODO: Handle preload link headers
        const pushManifest = getPushManifest(options.root, options.pushManifestPath);
        const resources = pushManifest[req.path];
        if (resources) {
            const root = options.root;
            for (const filename of Object.keys(resources)) {
                const stream = res.push(filename, {
                    request: { accept: '*/*' },
                    response: {
                        'content-type': mime.getType(filename),
                        // Add an X-header to the pushed request so we
                        // don't trigger pushes for pushes
                        'x-is-push': 'true'
                    }
                })
                    .on('error', (err) => console.error('failed to push', filename, err));
                fs.createReadStream(path.join(root, filename)).pipe(stream);
            }
        }
    }
}
exports.pushResources = pushResources;
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