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/*
* 2011 Peter 'Pita' Martischka (Primary Technology Ltd)
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS-IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
var async = require('async');
var Buffer = require('buffer').Buffer;
var fs = require('fs');
var path = require('path');
var zlib = require('zlib');
var settings = require('./Settings');
var semver = require('semver');
var existsSync = (semver.satisfies(process.version, '>=0.8.0')) ? fs.existsSync : path.existsSync;
var CACHE_DIR = path.normalize(path.join(settings.root, 'var/'));
CACHE_DIR = existsSync(CACHE_DIR) ? CACHE_DIR : undefined;
var responseCache = {};
/*
This caches and compresses 200 and 404 responses to GET and HEAD requests.
TODO: Caching and compressing are solved problems, a middleware configuration
should replace this.
*/
function CachingMiddleware() {
}
CachingMiddleware.prototype = new function () {
function handle(req, res, next) {
if (!(req.method == "GET" || req.method == "HEAD") || !CACHE_DIR) {
return next(undefined, req, res);
}
var old_req = {};
var old_res = {};
var supportsGzip =
(req.get('Accept-Encoding') || '').indexOf('gzip') != -1;
var path = require('url').parse(req.url).path;
var cacheKey = (new Buffer(path)).toString('base64').replace(/[\/\+=]/g, '');
fs.stat(CACHE_DIR + 'minified_' + cacheKey, function (error, stats) {
var modifiedSince = (req.headers['if-modified-since']
&& new Date(req.headers['if-modified-since']));
var lastModifiedCache = !error && stats.mtime;
if (lastModifiedCache && responseCache[cacheKey]) {
req.headers['if-modified-since'] = lastModifiedCache.toUTCString();
} else {
delete req.headers['if-modified-since'];
}
// Always issue get to downstream.
old_req.method = req.method;
req.method = 'GET';
var expirationDate = new Date(((responseCache[cacheKey] || {}).headers || {})['expires']);
if (expirationDate > new Date()) {
// Our cached version is still valid.
return respond();
}
var _headers = {};
old_res.setHeader = res.setHeader;
res.setHeader = function (key, value) {
// Don't set cookies, see issue #707
if (key.toLowerCase() === 'set-cookie') return;
_headers[key.toLowerCase()] = value;
old_res.setHeader.call(res, key, value);
};
old_res.writeHead = res.writeHead;
res.writeHead = function (status, headers) {
var lastModified = (res.getHeader('last-modified')
&& new Date(res.getHeader('last-modified')));
res.writeHead = old_res.writeHead;
if (status == 200) {
// Update cache
var buffer = '';
Object.keys(headers || {}).forEach(function (key) {
res.setHeader(key, headers[key]);
});
headers = _headers;
old_res.write = res.write;
old_res.end = res.end;
res.write = function(data, encoding) {
buffer += data.toString(encoding);
};
res.end = function(data, encoding) {
async.parallel([
function (callback) {
var path = CACHE_DIR + 'minified_' + cacheKey;
fs.writeFile(path, buffer, function (error, stats) {
callback();
});
}
, function (callback) {
var path = CACHE_DIR + 'minified_' + cacheKey + '.gz';
zlib.gzip(buffer, function(error, content) {
if (error) {
callback();
} else {
fs.writeFile(path, content, function (error, stats) {
callback();
});
}
});
}
], function () {
responseCache[cacheKey] = {statusCode: status, headers: headers};
respond();
});
};
} else if (status == 304) {
// Nothing new changed from the cached version.
old_res.write = res.write;
old_res.end = res.end;
res.write = function(data, encoding) {};
res.end = function(data, encoding) { respond(); };
} else {
res.writeHead(status, headers);
}
};
next(undefined, req, res);
// This handles read/write synchronization as well as its predecessor,
// which is to say, not at all.
// TODO: Implement locking on write or ditch caching of gzip and use
// existing middlewares.
function respond() {
req.method = old_req.method || req.method;
res.write = old_res.write || res.write;
res.end = old_res.end || res.end;
var headers = responseCache[cacheKey].headers;
var statusCode = responseCache[cacheKey].statusCode;
var pathStr = CACHE_DIR + 'minified_' + cacheKey;
if (supportsGzip && (headers['content-type'] || '').match(/^text\//)) {
pathStr = pathStr + '.gz';
headers['content-encoding'] = 'gzip';
}
var lastModified = (headers['last-modified']
&& new Date(headers['last-modified']));
if (statusCode == 200 && lastModified <= modifiedSince) {
res.writeHead(304, headers);
res.end();
} else if (req.method == 'GET') {
var readStream = fs.createReadStream(pathStr);
res.writeHead(statusCode, headers);
readStream.pipe(res);
} else {
res.writeHead(statusCode, headers);
res.end();
}
}
});
}
this.handle = handle;
}();
module.exports = CachingMiddleware;
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