/// <summary>
/// Base loop to decode URLs one by one in the chain
/// </summary>
/// <returns></returns>
public async Task <ResponseUrl> Get()
{
var list = new List <string>();
try
{
// 25 - is a maximum count of ShortURLs in the mode MultiURL (switching via WebUI)
if (_requestUrl.UrlList.Count > 25)
{
_requestUrl.UrlList.RemoveRange(25, _requestUrl.UrlList.Count - 25);
}
foreach (var uri in _requestUrl.UrlList)
{
if (string.IsNullOrEmpty(uri))
{
continue;
}
_urlItem = new UrlItem(uri);
list = new List <string>();
do
{
var urlParsed = new UrlParsedType(_urlItem.Next); // parsing URL
_urlItem.Next = urlParsed.Url; // ... i.e. searching any URL (if exists) int the request string
await GetLongUrlFromShort(_urlItem.Next);
if (_urlItem.Uncovered != null)
{
list.Add(_urlItem.Uncovered);
}
} while (!string.IsNullOrEmpty(_urlItem.Next));
if (_requestUrl.MultiUrl)
{
_responseUrl.Url.Add(list.Last());
}
else
{
_responseUrl.Url = list;
}
}
if (_responseUrl.Success && _requestUrl.Antivirus)
{
var mw = new MalwareScanner(_responseUrl);
await mw.Go();
}
return(_responseUrl);
}
catch
{
if (list.Any())
{
if (_requestUrl.MultiUrl)
{
_responseUrl.Url.Add(list.Last());
}
else
{
_responseUrl.Url = list;
}
}
return(_responseUrl);
}
}
/// <summary>
/// Core method to decode ShortURL
/// Algorithm is primitive and dumb: make http-request and analyze if there is some redirect or not
/// </summary>
/// <param name="url"></param>
/// <returns></returns>
private async Task GetLongUrlFromShort(string url)
{
_urlItem.Success = false;
_urlItem.Next = null;
_urlItem.Uncovered = null;
url = url.Trim(' ', '/');
Uri uri;
try
{
uri = new Uri(url);
}
catch (UriFormatException)
{
return;
}
ServicePointManager.SecurityProtocol = SecurityProtocolType.SystemDefault;
var http = new HttpClient();
http.DefaultRequestHeaders.Add("User-Agent",
"Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/53.0.2785.89 Safari/537.36");
http.DefaultRequestHeaders.Add("Accept-Encoding", "gzip, deflate, br");
http.DefaultRequestHeaders.Add("Accept",
"text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9");
http.DefaultRequestHeaders.Add("Connection", "keep-alive");
HttpResponseMessage response;
try
{
response = await http.GetAsync(uri, HttpCompletionOption.ResponseHeadersRead);
}
catch (HttpRequestException)
{
return;
}
if (response.StatusCode == HttpStatusCode.Redirect || // 302
response.StatusCode == HttpStatusCode.Moved || // 301
response.StatusCode == HttpStatusCode.RedirectKeepVerb || // 307
response.StatusCode == HttpStatusCode.RedirectMethod || // 303
response.StatusCode == HttpStatusCode.PermanentRedirect || // 308
response.StatusCode == HttpStatusCode.TemporaryRedirect // 307
)
{
_urlItem.Success = true;
var urlParsed = new UrlParsedType(response.RequestMessage.RequestUri.OriginalString.Trim(' ', '/'));
var parserUri = urlParsed.Url;
if (!string.Equals(parserUri, url, StringComparison.OrdinalIgnoreCase) &&
Uri.TryCreate(parserUri, UriKind.RelativeOrAbsolute, out var newUri) &&
IsUrlValid(newUri.OriginalString))
{
_urlItem.Next = newUri.OriginalString;
_urlItem.Uncovered = newUri.OriginalString;
return;
}
var ret = response.Headers.Location.OriginalString.Trim(' ', '/');
_urlItem.Next = ret;
_urlItem.Uncovered = ret;
return;
}
if (response.StatusCode == HttpStatusCode.OK) // 200
{
if (!string.Equals(response.RequestMessage.RequestUri.OriginalString.Trim(' ', '/'), url,
StringComparison.OrdinalIgnoreCase))
{
var ret = response.RequestMessage.RequestUri.OriginalString.Trim(' ', '/');
_urlItem.Next = ret;
_urlItem.Uncovered = ret;
}
_urlItem.Success = true;
return;
}
if (response.StatusCode == HttpStatusCode.BadGateway || // 502
response.StatusCode == HttpStatusCode.NotFound) // 404
{
var ret = response.RequestMessage.RequestUri.OriginalString.Trim(' ', '/');
_urlItem.Success = true;
_urlItem.Next = null;
_urlItem.Uncovered = ret;
}
}
