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crawler.js
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crawler.js
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'use strict';
var path = require('path')
, util = require('util')
, EventEmitter = require('events').EventEmitter
, request = require('request')
, _ = require('lodash')
, cheerio = require('cheerio')
, fs = require('fs')
, Bottleneck = require('bottleneckp')
, seenreq = require('seenreq')
, iconvLite = require('iconv-lite')
, typeis = require('type-is').is;
var whacko=null, level, levels = ['silly','debug','verbose','info','warn','error','critical'];
try{
whacko = require('whacko');
}catch(e){
e.code;
}
function defaultLog(){ //2016-11-24T12:22:55.639Z - debug:
if( levels.indexOf(arguments[0]) >= levels.indexOf(level) )
console.log(new Date().toJSON()+' - '+ arguments[0] +': CRAWLER %s', util.format.apply(util, Array.prototype.slice.call(arguments, 1)));
}
function checkJQueryNaming (options) {
if ('jquery' in options) {
options.jQuery = options.jquery;
delete options.jquery;
}
return options;
}
function readJqueryUrl (url, callback) {
if (url.match(/^(file:\/\/|\w+:|\/)/)) {
fs.readFile(url.replace(/^file:\/\//,''),'utf-8', function(err,jq) {
callback(err, jq);
});
} else {
callback(null, url);
}
}
function contentType(res){
return get(res,'content-type').split(';').filter(item => item.trim().length !== 0).join(';');
}
function get(res,field){
return res.headers[field.toLowerCase()] || '';
}
var log = defaultLog;
function Crawler (options) {
var self = this;
options = options||{};
if(['onDrain','cache'].some(key => key in options)){
throw new Error('Support for "onDrain", "cache" has been removed! For more details, see https://github.com/bda-research/node-crawler');
}
self.init(options);
}
// augment the prototype for node events using util.inherits
util.inherits(Crawler, EventEmitter);
Crawler.prototype.init = function init (options) {
var self = this;
var defaultOptions = {
autoWindowClose: true,
forceUTF8: true,
gzip: true,
incomingEncoding: null,
jQuery: true,
maxConnections: 10,
method: 'GET',
priority: 5,
priorityRange: 10,
rateLimit: 0,
referer: false,
retries: 3,
retryTimeout: 10000,
timeout: 15000,
skipDuplicates: false,
rotateUA: false,
homogeneous: false
};
// return defaultOptions with overridden properties from options.
self.options = _.extend(defaultOptions, options);
// you can use jquery or jQuery
self.options = checkJQueryNaming(self.options);
// Don't make these options persist to individual queries
self.globalOnlyOptions = ['maxConnections', 'rateLimit', 'priorityRange', 'homogeneous', 'skipDuplicates', 'rotateUA'];
self.limiters = new Bottleneck.Cluster(self.options.maxConnections,self.options.rateLimit,self.options.priorityRange, self.options.priority, self.options.homogeneous);
level = self.options.debug ? 'debug' : 'info';
if(self.options.logger)
log = self.options.logger.log.bind(self.options.logger);
self.log = log;
self.seen = new seenreq(self.options.seenreq);
self.seen.initialize().then(()=> log('debug', 'seenreq is initialized.')).catch(e => log('error', e));
self.on('_release', function(){
log('debug','Queue size: %d',this.queueSize);
if(this.limiters.empty)
return this.emit('drain');
});
};
Crawler.prototype.setLimiterProperty = function setLimiterProperty (limiter, property, value) {
var self = this;
switch(property) {
case 'rateLimit': self.limiters.key(limiter).setRateLimit(value);break;
default: break;
}
};
Crawler.prototype._inject = function _inject (response, options, callback) {
var $;
if (options.jQuery === 'whacko') {
if(!whacko){
throw new Error('Please install whacko by your own since `crawler` detected you specify explicitly');
}
$ = whacko.load(response.body);
callback(null, response, options, $);
}else if (options.jQuery === 'cheerio' || options.jQuery.name === 'cheerio' || options.jQuery === true) {
var defaultCheerioOptions = {
normalizeWhitespace: false,
xmlMode: false,
decodeEntities: true
};
var cheerioOptions = options.jQuery.options || defaultCheerioOptions;
$ = cheerio.load(response.body, cheerioOptions);
callback(null, response, options, $);
}else if (options.jQuery.jsdom) {
var jsdom = options.jQuery.jsdom;
var scriptLocation = path.resolve(__dirname, '../vendor/jquery-2.1.1.min.js');
//Use promises
readJqueryUrl(scriptLocation, function(err, jquery) {
try {
jsdom.env({
url: options.uri,
html: response.body,
src: [jquery],
done: function (errors, window) {
$ = window.jQuery;
callback(errors, response, options, $);
try {
window.close();
window = null;
} catch (err) {
log('error',err);
}
}
});
} catch (e) {
options.callback(e,{options}, options.release);
}
});
}
// Jquery is set to false are not set
else {
callback(null, response, options);
}
};
Crawler.prototype.isIllegal = function isIllegal (options) {
return (_.isNull(options) || _.isUndefined(options) || (!_.isString(options) && !_.isPlainObject(options)));
};
Crawler.prototype.direct = function direct (options) {
var self = this;
if(self.isIllegal(options) || !_.isPlainObject(options)) {
return log('warn','Illegal queue option: ', JSON.stringify(options));
}
if(!('callback' in options) || !_.isFunction(options.callback)) {
return log('warn','must specify callback function when using sending direct request with crawler');
}
options = checkJQueryNaming(options);
// direct request does not follow the global preRequest
options.preRequest = options.preRequest || null;
_.defaults(options, self.options);
// direct request is not allowed to retry
options.retries = 0;
// direct request does not emit event:'request' by default
options.skipEventRequest = _.isBoolean(options.skipEventRequest) ? options.skipEventRequest : true;
self.globalOnlyOptions.forEach(globalOnlyOption => delete options[globalOnlyOption]);
self._buildHttpRequest(options);
};
Crawler.prototype.queue = function queue (options) {
var self = this;
// Did you get a single object or string? Make it compatible.
options = _.isArray(options) ? options : [options];
options = _.flattenDeep(options);
for(var i = 0; i < options.length; ++i) {
if(self.isIllegal(options[i])) {
log('warn','Illegal queue option: ', JSON.stringify(options[i]));
continue;
}
self._pushToQueue(
_.isString(options[i]) ? {uri: options[i]} : options[i]
);
}
};
Crawler.prototype._pushToQueue = function _pushToQueue (options) {
var self = this;
// you can use jquery or jQuery
options = checkJQueryNaming(options);
_.defaults(options, self.options);
options.headers = _.assign({}, self.options.headers, options.headers);
// Remove all the global options from our options
// TODO we are doing this for every _pushToQueue, find a way to avoid this
self.globalOnlyOptions.forEach(globalOnlyOption => delete options[globalOnlyOption]);
// If duplicate skipping is enabled, avoid queueing entirely for URLs we already crawled
if (!self.options.skipDuplicates){
self._schedule(options);
return;
}
self.seen.exists(options, options.seenreq).then(rst => {
if(!rst){
self._schedule(options);
}
}).catch(e => log('error', e));
};
Crawler.prototype._schedule = function _scheduler(options){
var self = this;
self.emit('schedule',options);
self.limiters.key(options.limiter||'default').submit(options.priority,function(done, limiter){
options.release = function(){ done();self.emit('_release'); };
if(!options.callback)
options.callback = options.release;
if (limiter) {
self.emit('limiterChange', options, limiter);
}
if (options.html) {
self._onContent(null, options, {body:options.html,headers:{'content-type':'text/html'}});
} else if (typeof options.uri === 'function') {
options.uri(function(uri) {
options.uri = uri;
self._buildHttpRequest(options);
});
} else {
self._buildHttpRequest(options);
}
});
};
Crawler.prototype._buildHttpRequest = function _buildHTTPRequest (options) {
var self = this;
log('debug',options.method+' '+options.uri);
if(options.proxy)
log('debug','Use proxy: %s', options.proxy);
// Cloning keeps the opts parameter clean:
// - some versions of "request" apply the second parameter as a
// property called "callback" to the first parameter
// - keeps the query object fresh in case of a retry
var ropts = _.assign({},options);
if (!ropts.headers) { ropts.headers={}; }
if (ropts.forceUTF8) {ropts.encoding=null;}
// specifying json in request will have request sets body to JSON representation of value and
// adds Content-type: application/json header. Additionally, parses the response body as JSON
// so the response will be JSON object, no need to deal with encoding
if (ropts.json) {options.encoding=null;}
if (ropts.userAgent) {
if(self.options.rotateUA && _.isArray(ropts.userAgent)){
ropts.headers['User-Agent'] = ropts.userAgent[0];
// If "rotateUA" is true, rotate User-Agent
options.userAgent.push(options.userAgent.shift());
}else{
ropts.headers['User-Agent'] = ropts.userAgent;
}
}
if (ropts.referer) {
ropts.headers.Referer = ropts.referer;
}
if (ropts.proxies && ropts.proxies.length) {
ropts.proxy = ropts.proxies[0];
}
var doRequest = function(err) {
if(err) {
err.message = 'Error in preRequest' + (err.message ? ', '+err.message : err.message);
switch(err.op) {
case 'retry': log('debug', err.message + ', retry ' + options.uri);self._onContent(err,options);break;
case 'fail': log('debug', err.message + ', fail ' + options.uri);options.callback(err,{options:options},options.release);break;
case 'abort': log('debug', err.message + ', abort ' + options.uri);options.release();break;
case 'queue': log('debug', err.message + ', queue ' + options.uri);self.queue(options);options.release();break;
default: log('debug', err.message + ', retry ' + options.uri);self._onContent(err,options);break;
}
return;
}
if(ropts.skipEventRequest !== true) {
self.emit('request',ropts);
}
var requestArgs = ['uri','url','qs','method','headers','body','form','formData','json','multipart','followRedirect','followAllRedirects','maxRedirects','removeRefererHeader','encoding','pool','timeout','proxy','auth','oauth','strictSSL','jar','aws','gzip','time','tunnel','proxyHeaderWhiteList','proxyHeaderExclusiveList','localAddress','forever', 'agent', 'strictSSL', 'agentOptions', 'agentClass'];
request(_.pick.apply(self,[ropts].concat(requestArgs)), function(error,response) {
if (error) {
return self._onContent(error, options);
}
self._onContent(error,options,response);
});
};
if (options.preRequest && _.isFunction(options.preRequest)) {
options.preRequest(ropts, doRequest);
} else {
doRequest();
}
};
Crawler.prototype._onContent = function _onContent (error, options, response) {
var self = this;
if (error) {
log('error','Error '+error+' when fetching '+ (options.uri||options.url)+(options.retries ? ' ('+options.retries+' retries left)' : ''));
if (options.retries) {
setTimeout(function() {
options.retries--;
self._schedule(options);
options.release();
},options.retryTimeout);
} else{
options.callback(error,{options:options},options.release);
}
return;
}
if (!response.body) { response.body=''; }
log('debug','Got '+(options.uri||'html')+' ('+response.body.length+' bytes)...');
try{
self._doEncoding(options,response);
}catch(e){
log('error',e);
return options.callback(e,{options:options},options.release);
}
response.options = options;
if(options.method === 'HEAD' || !options.jQuery){
return options.callback(null,response,options.release);
}
var injectableTypes = ['html','xhtml','text/xml', 'application/xml', '+xml'];
if (!options.html && !typeis(contentType(response), injectableTypes)){
log('warn','response body is not HTML, skip injecting. Set jQuery to false to suppress this message');
return options.callback(null,response,options.release);
}
log('debug','Injecting');
self._inject(response, options, self._injected.bind(self));
};
Crawler.prototype._injected = function(errors, response, options, $){
log('debug','Injected');
response.$ = $;
options.callback(errors, response, options.release);
};
Crawler.prototype._doEncoding = function(options,response){
var self = this;
if(options.encoding === null){
return;
}
if (options.forceUTF8) {
var charset = options.incomingEncoding || self._parseCharset(response);
response.charset = charset;
log('debug','Charset ' + charset);
if (charset !== 'utf-8' && charset !== 'ascii') {// convert response.body into 'utf-8' encoded buffer
response.body = iconvLite.decode(response.body, charset);
}
}
response.body = response.body.toString();
};
Crawler.prototype._parseCharset = function(res){
//Browsers treat gb2312 as gbk, but iconv-lite not.
//Replace gb2312 with gbk, in order to parse the pages which say gb2312 but actually are gbk.
function getCharset(str){
var charset = (str && str.match(/charset=['"]?([\w.-]+)/i) || [0, null])[1];
return charset && charset.replace(/:\d{4}$|[^0-9a-z]/g, '') == 'gb2312' ? 'gbk' : charset;
}
function charsetParser(header, binary, default_charset = null) {
return getCharset(header) || getCharset(binary) || default_charset;
}
var charset = charsetParser(contentType(res));
if(charset)
return charset;
if(!typeis(contentType(res), ['html'])){
log('debug','Charset not detected in response headers, please specify using `incomingEncoding`, use `utf-8` by default');
return 'utf-8';
}
var body = res.body instanceof Buffer ? res.body.toString() : res.body;
charset = charsetParser(contentType(res),body,'utf-8');
return charset;
};
Object.defineProperty(Crawler.prototype,'queueSize',{
get:function(){
return this.limiters.unfinishedClients;
}
});
module.exports = Crawler;