public void Set(byte[] data)
{
// The input data must be the size of $size * 2. Otherwise there would be no need for a SplitRegisterHandle.
// Set $upper to the upper bytes of $data (Take $size bytes from the end of $data)
Upper.Set(Bitwise.Subarray(data, (int)Size));
// Set $lower to the lower $size bytes of $data.
Lower.Set(Bitwise.Cut(data, (int)Size));
}
public void Set(byte[] data)
{
// There are flaws in the caller if this is not already the same size.
data = Bitwise.Cut(data, (int)Capacity);
// If the destination handle is to DI, it would be a pointer not the actual value of DI
if (Destination.Code == XRegCode.DI)
{
ControlUnit.SetMemory(DestPtr, data);
}
// Otherwise set the value of the register
else
{
Destination.Set(data);
}
}
public override void Execute()
{
// Fetch the operand. There will only be one because it is always the A register which is destination and source.
byte[] Bytes = Fetch()[0];
// Half the fetched bytes(because the capacity is that of the destination, see summary), and sign extend it
// back to its former size.
// E.g, in pseudo,
// CBW()
// {
// Bytes = $AX;
// Bytes = Cut($Bytes, 1);
// AX = $Bytes;
// }
// From here it would be very simple to create CWDE and CDQE methods.
// Fortunately because of the interface the Opcode base class provides, this can be generalised.
Set(Bitwise.SignExtend(Bitwise.Cut(Bytes, (int)Capacity / 2), (byte)Capacity));
}
public Lea(DecodedTypes.ModRM input, OpcodeSettings settings = OpcodeSettings.NONE) : base("LEA", input, settings)
{
// EffectiveAddress property in the ModRM can be very helpful in the opcode. It is always a ulong, therefore does
// have to be cut to the correct size(nothing will happen in QWORD operation).
SourceAddress = Bitwise.Cut(BitConverter.GetBytes(input.EffectiveAddress), (int)Capacity);
}
public static ELF Parse(FileStream reader)
{
ELF ParsedElf;
// Check if the length is less than the minimum acceptable.
if (reader.Length < 0x34)
{
Logger.Log(LogCode.IO_INVALIDFILE, "Incomplete ELF header");
return(null);
}
// Determine the class of the elf. If the class byte is equal to 1, the ELF is 32 bit, 2 for 64-bit. Otherwise assume an invalid elf.
// The class byte is the 4th byte(0,1,2,3,4<-) so make sure the stream is at position 4. This is required to know the length of the header.
reader.Seek(4, SeekOrigin.Begin);
byte[] Elf_class = new byte[1];
reader.Read(Elf_class, 0, 1);
// Read and parse the rest of the header.
// All bytes are offset slightly because 5 bytes(magic bytes + class) have already been parsed.
// The offsets differ between elf32 and elf64 because addresses in elf64 must be 8 bytes; 4 bytes in elf32.
byte[] FileHeader;
switch (Elf_class[0])
{
case 0x01:
FileHeader = new byte[0x34 - 0x05];
reader.Read(FileHeader, 0, FileHeader.Length);
ParsedElf = new ELF()
{
Class = 32,
// The address of the section header table.
SHOffset = BitConverter.ToUInt32(FileHeader, 0x20 - 0x05),
// The length of each header in the section header table.
SHLength = BitConverter.ToUInt16(FileHeader, 0x2E - 0x05),
// The number of section headers in the section header table.
SHCount = BitConverter.ToUInt16(FileHeader, 0x30 - 0x05),
// The index of the section header containing the string names of all other sections in the section header table.
SHStrIndex = BitConverter.ToUInt16(FileHeader, 0x32 - 0x05)
};
break;
case 0x02:
FileHeader = new byte[0x40 - 0x05];
reader.Read(FileHeader, 0, FileHeader.Length);
ParsedElf = new ELF()
{
Class = 64,
SHOffset = BitConverter.ToUInt64(FileHeader, 0x28 - 0x05),
SHLength = BitConverter.ToUInt16(FileHeader, 0x3A - 0x05),
SHCount = BitConverter.ToUInt16(FileHeader, 0x3C - 0x05),
SHStrIndex = BitConverter.ToUInt16(FileHeader, 0x3E - 0x05)
};
break;
default:
Logger.Log(LogCode.IO_INVALIDFILE, "Invalid class byte in ELF header");
return(null);
}
;
// Make sure ELF uses x86-x64 instruction set
if (FileHeader[0xD] != 0x03 && FileHeader[0xD] != 0x3E)
{
Logger.Log(LogCode.IO_INVALIDFILE, "Input elf does not use the x86 instruction set");
return(null);
}
// Create a byte array with enough space to store the entire sh table.
byte[] SHTable = new byte[ParsedElf.SHLength * ParsedElf.SHCount];
// Seek the file to the offset of the SH table.
reader.Seek((long)ParsedElf.SHOffset, SeekOrigin.Begin);
// Read the entire SH table into $SHTable.
reader.Read(SHTable, 0, ParsedElf.SHLength * ParsedElf.SHCount);
// Use cut and subarray to cut out the shstrtab(section header string table; section that points to text names) from the SH table.
// Subarray cuts out the preceeding tables. The length of which is the number of tables before shstrtab(which happens to be the index of shstrtab) multiplied by
// the length of each table.
byte[] SHstrtab = Bitwise.Cut(Bitwise.Subarray(SHTable, ParsedElf.SHLength * ParsedElf.SHStrIndex), ParsedElf.SHLength);
// Get the size of strtab stored at offset 0x20 (elf32:0x14) of the section header and
// seek to the position in the elf file of the actual strtab(not the shstrtab section header)
int StrtabSize;
if (ParsedElf.Class == 32)
{
StrtabSize = BitConverter.ToInt32(SHstrtab, 0x14);
reader.Seek(BitConverter.ToUInt32(SHstrtab, 0x10), SeekOrigin.Begin);
}
else
{
StrtabSize = BitConverter.ToInt32(SHstrtab, 0x20);
reader.Seek(BitConverter.ToUInt32(SHstrtab, 0x18), SeekOrigin.Begin);
}
byte[] strtab = new byte[StrtabSize];
reader.Read(strtab, 0, StrtabSize);
// Read sh_name from every section in shtab and check if the offset($shstrtab + $offset = target) is the string ".text".
// .text is holds the user code and therefore is the only section this program cares about.
// If there isn't one, which most likely means this wasn't an elf file, so handle it because this file cannot be used.
for (int i = 0; i < ParsedElf.SHCount; i++)
{
if (ReadString(strtab, BitConverter.ToUInt32(SHTable, i * ParsedElf.SHLength)) == ".text")
{
if (ParsedElf.Class == 32)
{
// Store the EntryPoint(in the file not when in memory) and TextLength(length of the
// code in bytes) in the elf object.
ParsedElf.EntryPoint = BitConverter.ToUInt32(SHTable, i * ParsedElf.SHLength + 0x10);
ParsedElf.TextLength = BitConverter.ToUInt32(SHTable, i * ParsedElf.SHLength + 0x14);
}
else
{
ParsedElf.EntryPoint = BitConverter.ToUInt64(SHTable, i * ParsedElf.SHLength + 0x18);
ParsedElf.TextLength = BitConverter.ToUInt64(SHTable, i * ParsedElf.SHLength + 0x20);
}
break;
}
else if (i + 1 == ParsedElf.SHCount)
{
Logger.Log(LogCode.IO_INVALIDFILE, "ELF File had no .text section");
return(null);
}
}
// Finally copy all the bytes from the .text segment into $Instructions.
reader.Seek((long)ParsedElf.EntryPoint, SeekOrigin.Begin);
ParsedElf.Instructions = new byte[(int)ParsedElf.TextLength];
reader.Read(ParsedElf.Instructions, 0, (int)ParsedElf.TextLength);
return(ParsedElf);
}
public async Task <TestcaseResult> RunTestcase()
{
TestcaseResult Result = new TestcaseResult();
// Run every checkpoint. As they are ordered(this is automatically done due to the nature of how they are parsed), you will get half baked results if
// one checkpoint is out of the code address range or in the middle of an instruction. This is not something that can be fixed from this end because my
// code nor myself know what to expect as the results of your code if there is an error in the way that I execute your code. That is why I highly recommend
// properly testing on a real machine and basing your testcase of that.
for (int CheckpointNum = 0; CheckpointNum < CurrentTestcase.Checkpoints.Count; CheckpointNum++)
{
// Run until the checkpoint
Run();
// This Snapshot variable will keep the code nice and readable.
Context Snapshot = Handle.ShallowCopy();
// If the instruction pointer is not an address in the checkpoint list, it must have ended prematurely, i.e not all checkpoints were handled before execution finished.
// This is more than likely an error in how the testcase was written.
Checkpoint CurrentCheckpoint;
if (!CurrentTestcase.Checkpoints.TryGetValue(Snapshot.InstructionPointer, out CurrentCheckpoint))
{
Logger.Log(LogCode.TESTCASE_RUNTIME, "");
break;
}
// Iterate over every type of test present and handle them slightly differently.
List <CheckpointSubresult> CurrentSubresults = new List <CheckpointSubresult>();
foreach (TestRegister testReg in CurrentCheckpoint.ExpectedRegisters)
{
// Disassemble the mnemonic, provided by RegisterHandle. This will be different to how it was input as the full mnemonic that is representative of the size is given rather than a shorthand.
string Mnemonic = testReg.Register.DisassembleOnce();
// This is the "Found" value.
byte[] ActualValue = testReg.Register.FetchOnce();
// If CompareTo() returns 0, they are equal. ExpectedValue is cut to the same size as the register just to be sure.
bool RegistersEqual = ActualValue.CompareTo(Bitwise.Cut(BitConverter.GetBytes(testReg.ExpectedValue), (int)testReg.Register.Size), false) == 0;
// AND $Passed by $RegistersEqual. This means that if $RegistersEqual is ever false, Passed will stay false for the entire testcase.
Result.Passed &= RegistersEqual;
CurrentSubresults.Add(
new CheckpointSubresult
{
Passed = RegistersEqual,
Expected = $"${Mnemonic}=0x{testReg.ExpectedValue.ToString("X")}",
Found = $"${Mnemonic}=0x{BitConverter.ToUInt64(Bitwise.ZeroExtend(testReg.Register.FetchOnce(), 8), 0).ToString("X")}"
});
}
foreach (TestMemoryAddress testMem in CurrentCheckpoint.ExpectedMemory)
{
// ExactAddress will hold the starting address of the memory to compare.
ulong ExactAddress = 0;
// Build up the mnemonic throughout based on the conditions.
string Mnemonic = "";
// If there is an offset register(It would be null if there was not as TestMemoryAddress is a struct),
if (testMem.OffsetRegister != null)
{
// Use the RegisterHandle to do the disassembly.
Mnemonic = testMem.OffsetRegister.DisassembleOnce();
// This nested condition is unavoidable as there are certain things that need to happen if there is an offset register as well
// as an offset, and things that need to happen both ways if there is an offset at all.
if (testMem.Offset != 0)
{
// Append a +/- based on the offset as the absolute value is taken later. Just for quality of life really, It's alot easier than
// having to work out the magnitude of a twos compliment value in your head, even if its just subtraction it still leaves unnecessary
// work for the user.
Mnemonic += (testMem.Offset > 0) ? "+" : "-";
}
// Add the value of the register onto $ExactAddress.
ExactAddress += BitConverter.ToUInt64(testMem.OffsetRegister.FetchOnce(), 0);
}
// This secretly does two things. If there was no offset at all(no attribute), it was never assigned to into the struct, therefore its default
// value would be zero. Also, if offset was zero with an offset_register, its not very useful to see, so only the offset_register will be shown.
if (testMem.Offset != 0)
{
// The absolute value is taken because a negative is not possible at this point unless there was an offset register. In that case, a +/- was already
// added to show the sign.
Mnemonic += $"0x{Math.Abs(testMem.Offset).ToString("X")}";
// Finally add the offset onto $ExactAddress
ExactAddress += (ulong)testMem.Offset;
}
// Assume equality at first.
bool MemoryEqual = true;
// Create a new aob for the "Found" element.
byte[] FoundBytes = new byte[testMem.ExpectedBytes.Length];
// Compare the bytes in $Snapshot.Memory with the bytes in $ExpectedBytes
for (uint ByteOffset = 0; ByteOffset < testMem.ExpectedBytes.Length; ByteOffset++)
{
FoundBytes[ByteOffset] = Snapshot.Memory[ExactAddress + ByteOffset];
if (Snapshot.Memory[ExactAddress + ByteOffset] != testMem.ExpectedBytes[ByteOffset])
{
// If there is one or more bytes different, it must be false. A break cannot be added here
// because FoundBytes is still being filled up.
MemoryEqual = false;
}
}
// Same as with register.
Result.Passed &= MemoryEqual;
CurrentSubresults.Add(
new CheckpointSubresult
{
Passed = MemoryEqual,
Expected = $"[{Mnemonic}]={{{ParseBytes(testMem.ExpectedBytes)}}}",
Found = $"[{Mnemonic}]={{{ParseBytes(FoundBytes)}}}"
});
}
if (CurrentCheckpoint.TestFlags)
{
// A lot of the heavy work here is done by FlagSet.
// This method will ignore all flags that are FlagState.UNDEFINED in $ExpectedFlags but still compare the flags that do have a value.
// This makes sure flags do not have to be exhaustively specified in the testcase file. If only the carry flag is specified in an element,
// only the carry flag will be considered.
bool FlagsEqual = CurrentCheckpoint.ExpectedFlags.EqualsOrUndefined(ControlUnit.Flags);
Result.Passed &= FlagsEqual;
CurrentSubresults.Add(
new CheckpointSubresult
{
Passed = FlagsEqual,
Expected = CurrentCheckpoint.ExpectedFlags.ToString(),
// This produces a string representation of all the flags that are not FlagState.UNDEFINED in $Snapshot.Flags and $ExpectedFlags.
Found = Snapshot.Flags.And(CurrentCheckpoint.ExpectedFlags).ToString()
});
}
Result.CheckpointOutputs.Add(CurrentCheckpoint, CurrentSubresults);
}
return(Result);
}
