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using System ;
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using System.Collections.Concurrent ;
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using System.Globalization ;
using System.Linq ;
using System.Security.Cryptography ;
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using MediaBrowser.Common.Extensions ;
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using MediaBrowser.Controller ;
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using MediaBrowser.Controller.Authentication ;
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using MediaBrowser.Controller.Configuration ;
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using MediaBrowser.Controller.QuickConnect ;
using MediaBrowser.Controller.Security ;
using MediaBrowser.Model.QuickConnect ;
using Microsoft.Extensions.Logging ;
namespace Emby.Server.Implementations.QuickConnect
{
/// <summary>
/// Quick connect implementation.
/// </summary>
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public class QuickConnectManager : IQuickConnect , IDisposable
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{
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/// <summary>
/// The name of internal access tokens.
/// </summary>
private const string TokenName = "QuickConnect" ;
/// <summary>
/// The length of user facing codes.
/// </summary>
private const int CodeLength = 6 ;
/// <summary>
/// The time (in minutes) that the quick connect token is valid.
/// </summary>
private const int Timeout = 10 ;
private readonly RNGCryptoServiceProvider _rng = new ( ) ;
private readonly ConcurrentDictionary < string , QuickConnectResult > _currentRequests = new ( ) ;
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private readonly IServerConfigurationManager _config ;
private readonly ILogger < QuickConnectManager > _logger ;
private readonly IServerApplicationHost _appHost ;
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private readonly IAuthenticationRepository _authenticationRepository ;
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/// <summary>
/// Initializes a new instance of the <see cref="QuickConnectManager"/> class.
/// Should only be called at server startup when a singleton is created.
/// </summary>
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/// <param name="config">Configuration.</param>
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/// <param name="logger">Logger.</param>
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/// <param name="appHost">Application host.</param>
/// <param name="authenticationRepository">Authentication repository.</param>
public QuickConnectManager (
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IServerConfigurationManager config ,
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ILogger < QuickConnectManager > logger ,
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IServerApplicationHost appHost ,
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IAuthenticationRepository authenticationRepository )
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{
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_config = config ;
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_logger = logger ;
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_appHost = appHost ;
_authenticationRepository = authenticationRepository ;
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}
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/// <inheritdoc />
public bool IsEnabled = > _config . Configuration . QuickConnectAvailable ;
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/// <summary>
/// Assert that quick connect is currently active and throws an exception if it is not.
/// </summary>
private void AssertActive ( )
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{
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if ( ! IsEnabled )
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{
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throw new AuthenticationException ( "Quick connect is not active on this server" ) ;
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}
}
/// <inheritdoc/>
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public QuickConnectResult TryConnect ( )
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{
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AssertActive ( ) ;
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ExpireRequests ( ) ;
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var secret = GenerateSecureRandom ( ) ;
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var code = GenerateCode ( ) ;
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var result = new QuickConnectResult ( secret , code , DateTime . UtcNow ) ;
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_currentRequests [ code ] = result ;
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return result ;
}
/// <inheritdoc/>
public QuickConnectResult CheckRequestStatus ( string secret )
{
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AssertActive ( ) ;
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ExpireRequests ( ) ;
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string code = _currentRequests . Where ( x = > x . Value . Secret = = secret ) . Select ( x = > x . Value . Code ) . DefaultIfEmpty ( string . Empty ) . First ( ) ;
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if ( ! _currentRequests . TryGetValue ( code , out QuickConnectResult ? result ) )
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{
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throw new ResourceNotFoundException ( "Unable to find request with provided secret" ) ;
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}
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return result ;
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}
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/// <summary>
/// Generates a short code to display to the user to uniquely identify this request.
/// </summary>
/// <returns>A short, unique alphanumeric string.</returns>
private string GenerateCode ( )
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{
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Span < byte > raw = stackalloc byte [ 4 ] ;
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int min = ( int ) Math . Pow ( 10 , CodeLength - 1 ) ;
int max = ( int ) Math . Pow ( 10 , CodeLength ) ;
uint scale = uint . MaxValue ;
while ( scale = = uint . MaxValue )
{
_rng . GetBytes ( raw ) ;
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scale = BitConverter . ToUInt32 ( raw ) ;
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}
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int code = ( int ) ( min + ( ( max - min ) * ( scale / ( double ) uint . MaxValue ) ) ) ;
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return code . ToString ( CultureInfo . InvariantCulture ) ;
}
/// <inheritdoc/>
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public bool AuthorizeRequest ( Guid userId , string code )
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{
AssertActive ( ) ;
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ExpireRequests ( ) ;
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if ( ! _currentRequests . TryGetValue ( code , out QuickConnectResult ? result ) )
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{
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throw new ResourceNotFoundException ( "Unable to find request" ) ;
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}
if ( result . Authenticated )
{
throw new InvalidOperationException ( "Request is already authorized" ) ;
}
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var token = Guid . NewGuid ( ) ;
result . Authentication = token ;
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// Change the time on the request so it expires one minute into the future. It can't expire immediately as otherwise some clients wouldn't ever see that they have been authenticated.
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result . DateAdded = DateTime . Now . Add ( TimeSpan . FromMinutes ( 1 ) ) ;
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_authenticationRepository . Create ( new AuthenticationInfo
{
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AppName = TokenName ,
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AccessToken = token . ToString ( "N" , CultureInfo . InvariantCulture ) ,
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DateCreated = DateTime . UtcNow ,
DeviceId = _appHost . SystemId ,
DeviceName = _appHost . FriendlyName ,
AppVersion = _appHost . ApplicationVersionString ,
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UserId = userId
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} ) ;
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_logger . LogDebug ( "Authorizing device with code {Code} to login as user {userId}" , code , userId ) ;
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return true ;
}
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/// <summary>
/// Dispose.
/// </summary>
public void Dispose ( )
{
Dispose ( true ) ;
GC . SuppressFinalize ( this ) ;
}
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/// <summary>
/// Dispose.
/// </summary>
/// <param name="disposing">Dispose unmanaged resources.</param>
protected virtual void Dispose ( bool disposing )
{
if ( disposing )
{
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_rng . Dispose ( ) ;
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}
}
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private string GenerateSecureRandom ( int length = 32 )
{
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Span < byte > bytes = stackalloc byte [ length ] ;
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_rng . GetBytes ( bytes ) ;
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return Convert . ToHexString ( bytes ) ;
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}
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/// <summary>
/// Expire quick connect requests that are over the time limit. If <paramref name="expireAll"/> is true, all requests are unconditionally expired.
/// </summary>
/// <param name="expireAll">If true, all requests will be expired.</param>
private void ExpireRequests ( bool expireAll = false )
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{
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// All requests before this timestamp have expired
var minTime = DateTime . UtcNow . AddMinutes ( - Timeout ) ;
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// Expire stale connection requests
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foreach ( var ( _ , currentRequest ) in _currentRequests )
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{
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if ( expireAll | | currentRequest . DateAdded > minTime )
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{
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var code = currentRequest . Code ;
_logger . LogDebug ( "Removing expired request {Code}" , code ) ;
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if ( ! _currentRequests . TryRemove ( code , out _ ) )
{
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_logger . LogWarning ( "Request {Code} already expired" , code ) ;
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}
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}
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}
}
}
}