/* spiderFetch - ThreadPool QueueUserWorkItem method, gets the links on a page and adds them to the
* candidates list.
* @args - A _spiderFetch_SpiderDataWrapper object that will be cast back from a normal object. We
* have to take normal objects as input because = requires a single
* generic object to give its worker delegate (spiderFetch) as an argument.
*/
static void spiderFetch(Object args) {
_SpiderDataWrapper_spiderFetch wrapper = (_SpiderDataWrapper_spiderFetch) args;
Spider spider_obj = wrapper.getSpiderObject();
SpiderPage current_page = wrapper.getNewPage();
// check this thread into _thread_status, a list of int[]s, where [0] is the thread ID and [1] is
// the status- 0 for not working and 1 for working. thread_index is used later to change this
// thread id's status back to not working when it's done
int thread_index = 0;
bool thread_found = false;
for (int i = 0; i < spider_obj._thread_status.Count; i++) {
if (spider_obj._thread_status.ElementAt(i)[0] == Thread.CurrentThread.ManagedThreadId) {
spider_obj._thread_status.ElementAt(i)[1] = 1;
thread_index = i;
thread_found = true;
break;
}
}
// need to make a new entry for this thread id in _thread_status...
if (!thread_found) {
// lock the thread when performing an operation that depends on _thread_status.Count, using
// a local lock object
Object lock_obj = new Object();
lock (lock_obj) {
spider_obj._thread_status.Add(new int[]{ Thread.CurrentThread.ManagedThreadId, 1 });
thread_index = spider_obj._thread_status.Count - 1;
}
}
spider_obj.writeStatus("thread id: " + Thread.CurrentThread.ManagedThreadId + ", spiderFetch(): fetching " + current_page.getUrl());
_SpiderDataWrapper_getLinks gl_wrapper = getLinks(current_page, spider_obj);
string current_page_final_url = gl_wrapper.getFinalUrl();
List<SpiderPage> current_page_links = gl_wrapper.getNewLinks();
List<string> current_page_link_strings = new List<string>();
for (int q = 0; q < current_page_links.Count; q++) {
SpiderPage qth_page = current_page_links.ElementAt(q);
spider_obj._candidate_pages.Add(qth_page);
current_page_link_strings.Add(qth_page.getUrl());
}
spider_obj._candidate_pages.Add(new SpiderPage(current_page.getUrl(), current_page_final_url, current_page.getReferencedByUrls(), current_page_link_strings));
// set this thread id's status back to not working in _thread_status
spider_obj._thread_status.ElementAt(thread_index)[1] = 0;
}
/* getLinks() - find all the links on a given page
* @startp - the page to be scanned for links, represented as an SpiderPage object (which has a referring
* page)
* @s - the Spider object in use
*/
static _SpiderDataWrapper_getLinks getLinks(SpiderPage startp, Spider s) {
List<string> pre_pages = new List<string>();
string final_url = "";
List<SpiderPage> new_pages = new List<SpiderPage>();
StringBuilder sb = new StringBuilder();
byte[] buf = new byte[8192];
HttpWebRequest req = (HttpWebRequest)WebRequest.Create(startp.getUrl());
//req.Timeout = 1000;
HttpWebResponse resp = null;
try {
resp = (HttpWebResponse)req.GetResponse();
}
catch (Exception e) {
s.writeStatus("ERROR: " + e.Message);
s.writeStatus("\tpage - " + startp.getUrl() + "\n\t\treferred to by:");
List<string> curr_refs = startp.getReferencedByUrls();
for (int i = 0; i < curr_refs.Count; i++) {
s.writeStatus("\t\t\t" + curr_refs.ElementAt(i));
}
}
if (resp != null) {
// record the final Url after any redirects from this link
final_url = resp.ResponseUri.AbsoluteUri;
Stream resp_stream = resp.GetResponseStream();
string temp_string = null;
int count = 0;
do {
count = resp_stream.Read(buf, 0, buf.Length);
if (count != 0) {
temp_string = Encoding.ASCII.GetString(buf, 0, count);
sb.Append(temp_string);
}
}
while (count > 0);
HtmlDocument doc = new HtmlDocument();
doc.LoadHtml(sb.ToString());
var linksOnPage = from lnks in doc.DocumentNode.Descendants()
where lnks.Name == "a" &&
lnks.Attributes["href"] != null &&
lnks.InnerText.Trim().Length > 0
select new {
Url = lnks.Attributes["href"].Value,
};
foreach (var link in linksOnPage) {
if (link.Url.StartsWith("/")) {
if (link.Url.EndsWith("/")) {
pre_pages.Add(s.getBaseUrl() + link.Url);
}
else {
pre_pages.Add(s.getBaseUrl() + link.Url + "/");
}
}
};
List<string> distinct_pre_pages = pre_pages.Distinct().ToList();
for (int m = 0; m < distinct_pre_pages.Count; m++) {
new_pages.Add(new SpiderPage(distinct_pre_pages.ElementAt(m), startp.getUrl()));
}
}
return new _SpiderDataWrapper_getLinks(final_url, new_pages);
}
void spiderProcess() {
_thread_status.ElementAt(0)[1] = 1;
lock (this) {
int candidate_pages_count = this._candidate_pages.Count;
SpiderPage current_candidate_page = null;
SpiderPage current_master_page = null;
for (int i = 0; i < candidate_pages_count; i++) {
bool found = false;
current_candidate_page = this._candidate_pages.ElementAt(i);
if (current_candidate_page.finalUrlNeeded()) {
for (int m = 0; m < this.masterResults.Count; m++) {
current_master_page = this.masterResults.ElementAt(m);
if (!current_master_page.finalUrlNeeded()
&& current_candidate_page.getUrl() == current_master_page.getFinalUrl()) {
found = true;
List<string> current_candidate_page_ref_urls = current_candidate_page.getReferencedByUrls();
for (int g = 0; g < current_candidate_page_ref_urls.Count; g++) {
if (!current_master_page.getReferencedByUrls().Contains(current_candidate_page_ref_urls.ElementAt(g))) {
this.masterResults.ElementAt(j).addReferencedByUrl(current_candidate_page_ref_urls.ElementAt(g));
}
}
for (int j = 0; j < this.masterResults.Count; j++) {
current_master_page = this.masterResults.ElementAt(j);
if (current_master_page.finalUrlNeeded()) {
if (current_candidate_page.getUrl() == current_master_page.getUrl()) {
}
if (current_candidate_page.getFinalUrl() == this.masterResults.ElementAt(j).getFinalUrl()) {
found = true;
// add an alias entry in the masterResults if we were redirected here
if (current_candidate_page.getUrl() != current_candidate_page.getFinalUrl()) {
this.masterResults.ElementAt(j).addAliasUrl(current_candidate_page.getUrl());
}
// add all the linking URLs from the curr_page object to masterResults
List<string> current_page_link_urls = current_candidate_page.getLinkingToUrls();
for (int q = 0; q < current_page_link_urls.Count; q++) {
if (!this.masterResults.ElementAt(j).getLinkingToUrls().Contains(current_page_link_urls.ElementAt(q))) {
this.masterResults.ElementAt(j).addLinkingToUrl(current_page_link_urls.ElementAt(q));
}
}
// add all the referring URLs from the curr_page object to masterResults
List<string> current_page_ref_urls = current_candidate_page.getReferencedByUrls();
for (int g = 0; g < current_page_ref_urls.Count; g++) {
if (!this.masterResults.ElementAt(j).getReferencedByUrls().Contains(current_page_ref_urls.ElementAt(g))) {
this.masterResults.ElementAt(j).addReferencedByUrl(current_page_ref_urls.ElementAt(g));
}
}
break;
}
}
// if this is a new page...
if (!found) {
this.masterResults.Add(current_candidate_page);
ThreadPool.QueueUserWorkItem(new WaitCallback(spiderFetch), new _SpiderDataWrapper_spiderFetch(this, current_candidate_page));
}
}
// remove all the candidate pages we've just processed
_candidate_pages.RemoveRange(0, candidate_pages_count);
}
Thread.Sleep(30000);
if (this._candidate_pages.Count > 0) {
this.spiderProcess();
}
this._thread_status.ElementAt(0)[1] = 0;
}
