How to expand URLs in C-Sharp?

 How to expand URLs in C#?

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122

using System; using System.Text.RegularExpressions; using System.Net; using System.Web; public static class Program { public static string URLExpander(this string URL) { //removal ASCII and UNICODE control characters, if they exist string urlText = Regex.Replace(URL, @"[\u0000-\u0008|\u000B-\u000C|\u000E-\u001F|\u0080-\u009F]", ""); if (string.IsNullOrWhiteSpace(urlText)) return string.Empty; Uri uriResult; //validate URL bool result = Uri.TryCreate(urlText, UriKind.Absolute, out uriResult) && (uriResult.Scheme == Uri.UriSchemeHttp || uriResult.Scheme == Uri.UriSchemeHttps || uriResult.Scheme == Uri.UriSchemeFtp || uriResult.Scheme == Uri.UriSchemeFile ); //or other schemes if (!result) return string.Empty; //https://docs.microsoft.com/en-us/dotnet/api/system.net.httpwebrequest?view=netframework-4.8 HttpWebRequest req = null; HttpWebResponse response; try { req = (HttpWebRequest)WebRequest.Create(uriResult); req.Method = "HEAD"; req.AllowAutoRedirect = false; result = true; } catch (NotSupportedException) { result = false; //add your exception handling here } catch (ArgumentNullException) { result = false; //add your exception handling here } catch (System.Security.SecurityException) { result = false; //add your exception handling here } catch (UriFormatException) { result = false; //add your exception handling here } if (!result) return string.Empty; string redirectedURL = ""; try { response = (HttpWebResponse)req.GetResponse(); //https://en.wikipedia.org/wiki/List_of_HTTP_status_codes //304 Not Modified - Redirection to a previously cached result -> may not be a URL redirection //restrictive if ((int)response.StatusCode >= 300 && ((int)response.StatusCode < 400)) { redirectedURL = response.Headers[HttpResponseHeader.Location]; //or url = response.Headers["Location"]; } else if ((int)response.StatusCode < 300 || (int)response.StatusCode >= 400) //okay { redirectedURL = uriResult.ToString(); //set as validated URL } result = true; } catch (System.Net.WebException) { result = false; } catch (System.Net.ProtocolViolationException) { result = false; } catch (InvalidOperationException) { result = false; } catch (NotSupportedException) { result = false; } if (!result) return string.Empty; try { redirectedURL = HttpUtility.UrlDecode(redirectedURL); } catch { return string.Empty; } return redirectedURL; } public static void Main() { string testURL = "http://bit.ly/AzureAITranslation"; string testURL2 = "https://metadataconsulting.blogspot.com"; //sanity check //if (testURL == testURL.URLExpander()) //no redirect especially for status code 304! Console.WriteLine(testURL + "\nexpands to\n" + testURL.URLExpander()); Console.WriteLine(); Console.WriteLine(testURL2 + "\nexpands to\n" + testURL2.URLExpander()); } }