90 lines
No EOL
3.6 KiB
C#
90 lines
No EOL
3.6 KiB
C#
namespace Xorog.UniversalExtensions;
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public static class WebTools
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{
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/// <summary>
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/// Get the URL a redirect leads to (limited to StatusCodes 301, 303, 307, 308)
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/// </summary>
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/// <param name="url">The shortened URL</param>
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/// <returns>The URL the redirect leads to</returns>
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public static async Task<string> UnshortenUrl(string url, bool UseHeadMethod = true, int depth = 0, int maxDepth = 30)
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{
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if (depth > maxDepth)
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{
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throw new DepthLimitReachedException();
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}
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_logger?.LogDebug("Unshortening Url '{Url}', using head method: {UseHeadMethod}", url, UseHeadMethod);
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HttpClient client = new(new HttpClientHandler()
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{
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AllowAutoRedirect = false,
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AutomaticDecompression = DecompressionMethods.GZip,
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});
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client.Timeout = TimeSpan.FromSeconds(60);
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client.DefaultRequestHeaders.UserAgent.ParseAdd("Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36");
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client.DefaultRequestHeaders.Add("upgrade-insecure-requests", "1");
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client.DefaultRequestHeaders.Add("accept-encoding", "gzip, deflate, br");
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client.DefaultRequestHeaders.Add("accept-language", "en-US,en;q=0.9");
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client.MaxResponseContentBufferSize = 4096;
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HttpRequestMessage requestMessage = new HttpRequestMessage((UseHeadMethod ? HttpMethod.Head : HttpMethod.Get), url);
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CancellationTokenSource cancellationTokenSource = new CancellationTokenSource();
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var request_task = client.SendAsync(requestMessage, cancellationTokenSource.Token);
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try
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{
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await request_task.WaitAsync(TimeSpan.FromSeconds(3));
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}
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catch (Exception)
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{
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if (UseHeadMethod)
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return await UnshortenUrl(url, false, depth + 1, maxDepth);
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throw;
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}
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if (!request_task.IsCompleted)
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cancellationTokenSource.Cancel();
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if (UseHeadMethod && request_task.IsFaulted && request_task.Exception.InnerException.GetType() == typeof(HttpRequestException))
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{
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_logger?.LogWarning("Unshortening Url '{Url}' failed, falling back to non-head method", url);
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return await UnshortenUrl(url, false, depth + 1, maxDepth);
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}
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var statuscode = request_task.Result.StatusCode;
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var header = request_task.Result.Headers;
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if (UseHeadMethod && statuscode is HttpStatusCode.NotFound or HttpStatusCode.InternalServerError)
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{
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_logger?.LogWarning("Unshortening Url '{Url}' failed, falling back to non-head method", url);
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return await UnshortenUrl(url, false, depth + 1, maxDepth);
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}
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if (statuscode is HttpStatusCode.Found
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or HttpStatusCode.Redirect
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or HttpStatusCode.SeeOther
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or HttpStatusCode.RedirectKeepVerb
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or HttpStatusCode.RedirectMethod
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or HttpStatusCode.PermanentRedirect
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or HttpStatusCode.TemporaryRedirect)
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{
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if (header is not null && header.Location is not null)
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{
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if (header.Location.IsAbsoluteUri)
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return await UnshortenUrl(header.Location.AbsoluteUri, UseHeadMethod, depth + 1, maxDepth);
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else
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return await UnshortenUrl(new Uri(requestMessage.RequestUri.GetLeftPart(UriPartial.Authority).ToString() + header.Location.ToString()).AbsoluteUri, UseHeadMethod, depth + 1, maxDepth);
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}
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else
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return url;
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}
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else
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return url;
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}
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}
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public class DepthLimitReachedException : Exception { } |