67 lines
2.0 KiB
JavaScript
67 lines
2.0 KiB
JavaScript
'use strict';
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var as = require('../../lib/as.js');
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var debug = require('debug')('express-http-proxy');
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var zlib = require('zlib');
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function isResGzipped(res) {
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return res.headers['content-encoding'] === 'gzip';
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}
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function zipOrUnzip(method) {
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return function(rspData, res) {
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return (isResGzipped(res) && rspData.length) ? zlib[method](rspData) : rspData;
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};
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}
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var maybeUnzipResponse = zipOrUnzip('gunzipSync');
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var maybeZipResponse = zipOrUnzip('gzipSync');
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function verifyBuffer(rspd, reject) {
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if (!Buffer.isBuffer(rspd)) {
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return reject(new Error('userResDecorator should return string or buffer as data'));
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}
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}
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function updateHeaders(res, rspdBefore, rspdAfter, reject) {
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if (!res.headersSent) {
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res.set('content-length', rspdAfter.length);
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} else if (rspdAfter.length !== rspdBefore.length) {
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var error = '"Content-Length" is already sent,' +
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'the length of response data can not be changed';
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return reject(new Error(error));
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}
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}
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function decorateProxyResBody(container) {
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var resolverFn = container.options.userResDecorator;
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if (!resolverFn) {
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return Promise.resolve(container);
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}
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var proxyResData = maybeUnzipResponse(container.proxy.resData, container.proxy.res);
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var proxyRes = container.proxy.res;
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var req = container.user.req;
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var res = container.user.res;
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if (res.statusCode === 304) {
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debug('Skipping userResDecorator on response 304');
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return Promise.resolve(container);
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}
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return Promise
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.resolve(resolverFn(proxyRes, proxyResData, req, res))
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.then(function(modifiedResData) {
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return new Promise(function(resolve, reject) {
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var rspd = as.buffer(modifiedResData, container.options);
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verifyBuffer(rspd, reject);
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updateHeaders(res, proxyResData, rspd, reject);
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container.proxy.resData = maybeZipResponse(rspd, container.proxy.res);
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resolve(container);
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});
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});
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}
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module.exports = decorateProxyResBody;
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