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Add error handling to scrambling (#9)

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Rebecca Wallander
2023-10-15 23:42:53 +02:00
committed by GitHub
parent 089ba52732
commit fd04357f56
1 changed files with 25 additions and 12 deletions
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37
DVD/Sector.cs
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@@ -35,6 +35,7 @@ using System;
using System.Collections.Generic; using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis; using System.Diagnostics.CodeAnalysis;
using System.Linq; using System.Linq;
using Aaru.CommonTypes.Enums;
using Aaru.Helpers; using Aaru.Helpers;
namespace Aaru.Decoders.DVD; namespace Aaru.Decoders.DVD;
@@ -204,38 +205,50 @@ public sealed class Sector
/// </summary> /// </summary>
/// <param name="sector">Buffer of the scrambled sector</param> /// <param name="sector">Buffer of the scrambled sector</param>
/// <param name="cipher">Buffer of the scrambling cipher</param> /// <param name="cipher">Buffer of the scrambling cipher</param>
/// <returns>The unscrambled sector.</returns> /// <param name="scrambled">Buffer of unscrambled sector data</param>
static byte[] UnscrambleSector(byte[] sector, IReadOnlyList<byte> cipher) /// <returns>The Error.</returns>
static ErrorNumber UnscrambleSector(byte[] sector, IReadOnlyList<byte> cipher, out byte[] scrambled)
{ {
var scrambled = new byte[sector.Length]; scrambled = new byte[sector.Length];
Array.Copy(sector, 0, scrambled, 0, sector.Length); Array.Copy(sector, 0, scrambled, 0, sector.Length);
for(var i = 0; i < 2048; i++) for(var i = 0; i < 2048; i++)
scrambled[i + 12] = (byte)(sector[i + 12] ^ cipher[i]); scrambled[i + 12] = (byte)(sector[i + 12] ^ cipher[i]);
return ComputeEdc(0, scrambled, 2060) != BigEndianBitConverter.ToUInt32(sector, 2060) ? sector : scrambled; return ComputeEdc(0, scrambled, 2060) != BigEndianBitConverter.ToUInt32(sector, 2060)
? ErrorNumber.NotVerifiable
: ErrorNumber.NoError;
} }
public byte[] Scramble(byte[] sector) public ErrorNumber Scramble(byte[] sector, out byte[] scrambled)
{ {
scrambled = new byte[sector.Length];
if(sector is not { Length: 2064 }) if(sector is not { Length: 2064 })
return sector; return ErrorNumber.NotSupported;
byte[]? cipher = GetSeed(sector); byte[]? cipher = GetSeed(sector);
return cipher == null ? sector : UnscrambleSector(sector, cipher); return cipher == null ? ErrorNumber.UnrecognizedFormat : UnscrambleSector(sector, cipher, out scrambled);
} }
public byte[] Scramble(byte[] sector, uint transferLength) public ErrorNumber Scramble(byte[] sector, uint transferLength, out byte[] scrambled)
{ {
var scrambled = new byte[sector.Length]; scrambled = new byte[sector.Length];
if(sector.Length % 2064 != 0 || sector.Length / 2064 != transferLength) if(sector.Length % 2064 != 0 || sector.Length / 2064 != transferLength)
return sector; return ErrorNumber.NotSupported;
for(uint i = 0; i < transferLength; i++) for(uint i = 0; i < transferLength; i++)
Array.Copy(Scramble(sector.Skip((int)(i * 2064)).Take(2064).ToArray()), 0, scrambled, i * 2064, 2064); {
ErrorNumber error = Scramble(sector.Skip((int)(i * 2064)).Take(2064).ToArray(), out byte[]? currentSector);
return scrambled; if(error != ErrorNumber.NoError)
return error;
Array.Copy(currentSector, 0, scrambled, i * 2064, 2064);
}
return ErrorNumber.NoError;
} }
} }