private void ThreadStartFunction()
{
CrawlerWebRequest request = null;
while (state_ == EngineState.engine_state_running &&
int.Parse(Thread.CurrentThread.Name) < this.threadsCount)
{
CrawlerUri uri = DequeueUri();
if (uri != null && uri.depth_ <= crawlerSettings_.maxDepth_)
{
if (crawlerOutput_.FindCrawlerUri(uri) != null) // this uri has been parsed.
{
continue; // do not parse it.
}
ParseUri(uri, ref request);
if (crawlerSettings_.sleepConnectTime_ > 0)
{
Thread.Sleep(crawlerSettings_.sleepConnectTime_ * 1000);
}
}
else
{
Thread.Sleep(crawlerSettings_.sleepFetchTime_ * 1000);
}
}
}
private void ParseUri(CrawlerUri uri, ref CrawlerWebRequest request)
{
try
{
// create web request
request = CrawlerWebRequest.Create(uri, request, crawlerSettings_.keepAlive_);
// set request timeout
request.timeOut_ = crawlerSettings_.requestTimeout_ * 1000;
// retrieve response from web request
CrawlerWebResponse response = request.GetResponse();
// check for redirection
if (response.responseUri_.Equals(uri) == false)
{
// add the new uri to the queue
EnqueueUri(new CrawlerUri(response.responseUri_.AbsoluteUri), true);
request = null;
return;
}
// check for allowed MIME types
if (crawlerSettings_.allowAllMIMETypes_ == false &&
crawlerSettings_.allowedMIMETypes_.Length > 0 &&
response.contentType_ != null)
{
// sample response.contentType: text/html; charset=utf-8
string strContentType = response.contentType_.ToLower();
int nIndex = strContentType.IndexOf(';');
if (nIndex != -1)
{
strContentType = strContentType.Substring(0, nIndex);
}
nIndex = crawlerSettings_.allowedMIMETypes_.IndexOf(strContentType);
if (strContentType.IndexOf('*') == -1 && nIndex == -1)
{
// log: this MIME type is not listed.
request = null;
uri.state_ = CrawlerUriParseState.uri_state_not_allowed_MIME_type;
return;
}
// find numbers
Match match = new Regex(@"\d+").Match(crawlerSettings_.allowedMIMETypes_, nIndex);
int nMin = int.Parse(match.Value) * 1024;
match = match.NextMatch();
int nMax = int.Parse(match.Value) * 1024;
if (nMin < nMax && (response.contentLength_ < nMin || response.contentLength_ > nMax))
{
// TODO: Content's length is not correct, minimize length is nMin, maximize length is nMax,
// but content's length is response.contentLength_
request = null;
return;
}
}
// check for excluded response file extension
bool shouldBeParsed = true;
foreach (string ext in crawlerSettings_.excludeFiles_)
{
if (ext.Trim().Length > 0 && uri.AbsoluteUri.ToLower().EndsWith(ext) == true)
{
shouldBeParsed = false;
break;
}
}
// construct path in the hard disk
string strLocalPath = uri.LocalPath;
// check if the path ends with / to can crate the file on the HD
if (strLocalPath.EndsWith("/") == true)
{
// check if there is no query like (.asp?i=32&j=212)
if (uri.Query == "")
{
// add a default name for / ended paths
strLocalPath += "default.html";
}
}
// check if the uri includes a query string
if (uri.Query != "")
{
// construct the name from the query hash value to be the same if we download it again
strLocalPath += uri.Query.GetHashCode() + ".html";
}
// construct the full path folder
string BasePath = crawlerSettings_.downloadfolder_ + "\\" + uri.Host + Path.GetDirectoryName(uri.AbsolutePath);
// check if the folder not found
if (Directory.Exists(BasePath) == false)
{
// create the folder
Directory.CreateDirectory(BasePath);
}
// construct the full path name of the file
string PathName = crawlerSettings_.downloadfolder_ + "\\" + uri.Host + strLocalPath.Replace("%20", " ");
// open the output file
FileStream fStream = File.Open(PathName, FileMode.Create, FileAccess.Write, FileShare.ReadWrite);
BinaryWriter bWriter = new BinaryWriter(fStream);
// receive response buffer
string strResponse = "";
byte[] recvBuffer = new byte[8192];
int nBytes, nTotalBytes = 0;
// loop to receive response buffer
while ((nBytes = response.socket_.Receive(recvBuffer, 0, 8192, SocketFlags.None)) > 0)
{
// increment total received bytes
nTotalBytes += nBytes;
// write received buffer to file
bWriter.Write(recvBuffer, 0, nBytes);
// check if the uri type not binary to can be parsed for refs
if (shouldBeParsed == true)
{
// add received buffer to response string
strResponse += Encoding.ASCII.GetString(recvBuffer, 0, nBytes);
}
// check if connection Keep-Alive to can break the loop if response completed
if (response.keepAlive_ && nTotalBytes >= response.contentLength_ && response.contentLength_ > 0)
{
break;
}
}
// close output stream
bWriter.Close();
fStream.Close();
if (!response.keepAlive_)
{
// close response
response.Close();
}
// increment total file count
crawlerOutput_.fileCount_++;
// increment total bytes count
crawlerOutput_.byteCount_ += nTotalBytes;
if (shouldBeParsed == true)
{
// check for restricted words
foreach (string strExcludeWord in crawlerSettings_.excludeWords_)
{
if (strExcludeWord.Trim().Length > 0 && strResponse.IndexOf(strExcludeWord) != -1)
{
File.Delete(PathName);
return;
}
}
// parse the page to search for refs
string strRef = @"(href|HREF|src|SRC)[ ]*=[ ]*[""'][^""'#>]+[""']";
MatchCollection matches = new Regex(strRef).Matches(strResponse);
crawlerOutput_.uriCount_ += matches.Count;
foreach (Match match in matches)
{
strRef = match.Value.Substring(match.Value.IndexOf('=') + 1).Trim('"', '\'', '#', ' ', '>');
try
{
if (strRef.IndexOf("..") != -1 || strRef.StartsWith("/") == true || strRef.StartsWith("http://") == false)
{
strRef = new Uri(uri, strRef).AbsoluteUri;
}
CrawlerUri.Normalize(ref strRef);
CrawlerUri newUri = new CrawlerUri(strRef);
if (newUri.Scheme != Uri.UriSchemeHttp && newUri.Scheme != Uri.UriSchemeHttps)
{
continue;
}
if (newUri.Host != uri.Host && crawlerSettings_.keepSameServer_ == true)
{
continue;
}
newUri.depth_ = uri.depth_ + 1;
EnqueueUri(newUri, true);
}
catch (Exception)
{
}
}
}
}
catch (Exception ex)
{
request = null;
}
finally
{
}
}
