90 lines
3.6 KiB
C#
90 lines
3.6 KiB
C#
using System.Text;
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using System.Text.RegularExpressions;
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using Manager.YouTube.Util.Cipher.Operations;
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namespace Manager.YouTube.Util.Cipher;
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public partial class CipherDecoder
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{
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public required string Version { get; init; }
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public required string OriginalRelativeUrl { get; init; }
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public readonly IReadOnlyCollection<ICipherOperation> Operations;
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private CipherDecoder(IEnumerable<ICipherOperation> operations)
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{
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Operations = operations.ToList();
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if (Operations.Count == 0)
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{
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throw new ArgumentNullException(nameof(operations), "No decipher operations given.");
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}
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}
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public static async Task<CipherDecoder> CreateAsync(string relativeUrl, string version, YouTubeClient? client = null)
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{
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var operations = await GetCipherOperations(relativeUrl, client);
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var decoder = new CipherDecoder(operations)
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{
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OriginalRelativeUrl = relativeUrl,
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Version = version
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};
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return decoder;
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}
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private static async Task<IEnumerable<ICipherOperation>> GetCipherOperations(string relativeUrl, YouTubeClient? client = null)
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{
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var downloadRequest = new HttpRequestMessage(HttpMethod.Get, new Uri($"{NetworkService.Origin}/{relativeUrl}"));
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var downloadResponse = await NetworkService.DownloadBytesAsync(downloadRequest, client);
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if (!downloadResponse.IsSuccess)
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{
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return [];
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}
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var playerJs = Encoding.UTF8.GetString(downloadResponse.Value.Data);
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if (string.IsNullOrWhiteSpace(playerJs))
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{
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return [];
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}
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var functionBody = FunctionBodyRegex().Match(playerJs).Groups[0].ToString();
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var definitionBody = DefinitionBodyRegex().Match(functionBody).Groups[1].Value;
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var decipherDefinition = Regex.Match(playerJs, $@"var\s+{definitionBody}=\{{(\w+:function\(\w+(,\w+)?\)\{{(.*?)\}}),?\}};", RegexOptions.Singleline).Groups[0].ToString();
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List<ICipherOperation> operations = [];
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foreach (var statement in functionBody.Split(';'))
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{
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// Get the name of the function called in this statement
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var calledFuncName = StatementFunctionNameRegex().Match(statement).Groups[1].Value;
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if (string.IsNullOrWhiteSpace(calledFuncName))
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continue;
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if (Regex.IsMatch(decipherDefinition, $@"{Regex.Escape(calledFuncName)}:\bfunction\b\([a],b\).(\breturn\b)?.?\w+\."))
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{
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var index = int.Parse(OperationIndexRegex().Match(statement).Groups[1].Value);
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operations.Add(new CipherSlice(index));
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}
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else if (Regex.IsMatch(decipherDefinition, $@"{Regex.Escape(calledFuncName)}:\bfunction\b\(\w+\,\w\).\bvar\b.\bc=a\b"))
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{
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var index = int.Parse(OperationIndexRegex().Match(statement).Groups[1].Value);
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operations.Add(new CipherSwap(index));
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}
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else if (Regex.IsMatch(decipherDefinition, $@"{Regex.Escape(calledFuncName)}:\bfunction\b\(\w+\)"))
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{
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operations.Add(new CipherReverse());
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}
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}
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return [];
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}
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[GeneratedRegex(@"(\w+)=function\(\w+\){(\w+)=\2\.split\(\x22{2}\);.*?return\s+\2\.join\(\x22{2}\)}")]
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private static partial Regex FunctionBodyRegex();
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[GeneratedRegex("([\\$_\\w]+).\\w+\\(\\w+,\\d+\\);")]
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private static partial Regex DefinitionBodyRegex();
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[GeneratedRegex(@"\(\w+,(\d+)\)")]
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private static partial Regex OperationIndexRegex();
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[GeneratedRegex(@"\w+(?:.|\[)(\""?\w+(?:\"")?)\]?\(")]
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private static partial Regex StatementFunctionNameRegex();
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} |