Delphi. Вы задаете вопрос, мы отвечаем.

Как оказалось все сложное уже решено до нас, или "все уже украдено до нас" (С) Народная мудрость.
Вам надо всего-то сходить по ссылке: http://www.basegraph.com/bg/tutorials/eng_tutor_dlltools/dlltools.html и забрать оттуда DLLTools. Из этого архива нам нужен только 1 фаил. DLLLoader.pas
Его подключаете к проекту и код быстро преобразуется в ещё более простой чем "простой метод", а именно:

Код:

var
dll:TResourceStream;
obj:TDLLLoader;
begin
obj:=TDLLLoader.Create;
dll:=TResourceStream.Create(HInstance, 'UNPACK', 'DLL');
obj.Load(dll);
dll.Free;

Дальше надо настраивать адреса процедур через: obj.FindExport();
Однако, TDFUnRar работает с LoadLibrary и GetProcAddress, что делать? Так как пока никто не придумал как грузить дллки так, чтоб процесс был зквивалентен LoadLibraryA(W), то мы делаем как умеем.
Цель: заставить GetProcAddress и LoadLibrary "скушать" нашу длл.
Идея: Идея не нова, она называется сплайсинг АПИ функций. Кому интересно, подробная статья лежит на wasm.ru (тут) Я-же просто приведу код:

Cкрытый текст (кликните здесь для просмотра)

Код:

unit APIHook;

interface

uses Windows, SysUtils, Classes, DLLLoader;

procedure LoadResourceDll(Instance: THandle; ResName: PChar; ResType: PChar; DllName:String='');
procedure SetHookState(Value:Boolean);

implementation

type
RProcInfo=record
Module:THandle;
Entry:Pointer;
OldCode:Array [0..5] of Byte;
InjectCode:Array[0..5] of Byte;
Name:String;
end;
RDLLInfo=record
Obj:TDLLLoader;
Name:String;
Loaded:Cardinal;
end;
PDLLInfo=^RDLLInfo;
TDLLLoaderList=class
Private
RelockedInfo:Array of RProcInfo;
RILen:Cardinal;
DLLInfo:Array of RDLLInfo;
RDILen:Cardinal;
FIsActive:Boolean;
public
constructor Create;
destructor Destroy;
property IsActive:Boolean read FIsActive write FIsActive;
procedure AddDLLLoaderAs(Who:TDLLLoader; DllName:String);
end;

var
DLLManager:TDLLLoaderList;

procedure LoadResourceDll(Instance: THandle; ResName: PChar; ResType: PChar; DllName:String='');
var
dll:TResourceStream;
obj:TDLLLoader;
RName:String;
begin
if DllName='' Then DllName:=ResName;
RName:=ResName;
obj:=TDLLLoader.Create;
dll:=TResourceStream.Create(Instance, RName, ResType);
obj.Load(dll);
dll.Free;
DLLManager.AddDLLLoaderAs(obj, UpperCase(DllName));
end;

procedure SetHookState(Value:Boolean);
begin
DLLManager.IsActive:=Value;
end;

function NewLoadLibraryA(lpLibFileName: PAnsiChar): HMODULE; stdcall;
var
Written:Cardinal;
S:String;
begin
If not DLLManager.FIsActive Then Begin
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[0].Entry, @DLLManager.RelockedInfo[0].OldCode, 6, Written);
Result:=LoadLibraryA(lpLibFileName);
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[0].Entry, @DLLManager.RelockedInfo[0].InjectCode, 6, Written);
End Else Begin
S:=lpLibFileName;
S:=UpperCase(S);
For Written:=0 to DLLManager.RDILen-1 do begin
If DLLManager.DLLInfo[Written].Name=S then begin
Result:=Cardinal(@DLLManager.DLLInfo[Written]);
Inc(DLLManager.DLLInfo[Written].Loaded);
Exit;
end;
end;
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[0].Entry, @DLLManager.RelockedInfo[0].OldCode, 6, Written);
Result:=LoadLibraryA(lpLibFileName);
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[0].Entry, @DLLManager.RelockedInfo[0].InjectCode, 6, Written);
End;
end;

function NewLoadLibraryW(lpLibFileName: PWideChar): HMODULE; stdcall;
var
Written:Cardinal;
S:String;
begin
If not DLLManager.FIsActive Then Begin
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[1].Entry, @DLLManager.RelockedInfo[1].OldCode, 6, Written);
Result:=LoadLibraryW(lpLibFileName);
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[1].Entry, @DLLManager.RelockedInfo[1].InjectCode, 6, Written);
End Else Begin
S:=lpLibFileName;
S:=UpperCase(S);
For Written:=0 to DLLManager.RDILen-1 do begin
If DLLManager.DLLInfo[Written].Name=S then begin
Result:=Cardinal(@DLLManager.DLLInfo[Written]);
Inc(DLLManager.DLLInfo[Written].Loaded);
Exit;
end;
end;
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[1].Entry, @DLLManager.RelockedInfo[1].OldCode, 6, Written);
Result:=LoadLibraryW(lpLibFileName);
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[1].Entry, @DLLManager.RelockedInfo[1].InjectCode, 6, Written);
End;
end;

function NewLoadLibraryExA(lpLibFileName: PAnsiChar; hFile: THandle; dwFlags: DWORD): HMODULE; stdcall;
var
Written:Cardinal;
S:String;
begin
If not DLLManager.FIsActive Then Begin
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[2].Entry, @DLLManager.RelockedInfo[2].OldCode, 6, Written);
Result:=LoadLibraryExA(lpLibFileName, hFile, dwFlags);
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[2].Entry, @DLLManager.RelockedInfo[2].InjectCode, 6, Written);
End Else Begin
If ((dwFlags AND LOAD_LIBRARY_AS_DATAFILE) <> LOAD_LIBRARY_AS_DATAFILE) Then Begin
S:=lpLibFileName;
S:=UpperCase(S);
For Written:=0 to DLLManager.RDILen-1 do begin
If DLLManager.DLLInfo[Written].Name=S then begin
Result:=Cardinal(@DLLManager.DLLInfo[Written]);
Inc(DLLManager.DLLInfo[Written].Loaded);
Exit;
end;
end;
End;
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[2].Entry, @DLLManager.RelockedInfo[2].OldCode, 6, Written);
Result:=LoadLibraryExA(lpLibFileName, hFile, dwFlags);
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[2].Entry, @DLLManager.RelockedInfo[2].InjectCode, 6, Written);
End;
end;

function NewLoadLibraryExW(lpLibFileName: PWideChar; hFile: THandle; dwFlags: DWORD): HMODULE; stdcall;
var
Written:Cardinal;
S:String;
begin
If not DLLManager.FIsActive Then Begin
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[3].Entry, @DLLManager.RelockedInfo[3].OldCode, 6, Written);
Result:=LoadLibraryExW(lpLibFileName, hFile, dwFlags);
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[3].Entry, @DLLManager.RelockedInfo[3].InjectCode, 6, Written);
End Else Begin
If ((dwFlags AND LOAD_LIBRARY_AS_DATAFILE) <> LOAD_LIBRARY_AS_DATAFILE) Then Begin
S:=lpLibFileName;
S:=UpperCase(S);
For Written:=0 to DLLManager.RDILen-1 do begin
If DLLManager.DLLInfo[Written].Name=S then begin
Result:=Cardinal(@DLLManager.DLLInfo[Written]);
Inc(DLLManager.DLLInfo[Written].Loaded);
Exit;
end;
end;
End;
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[3].Entry, @DLLManager.RelockedInfo[3].OldCode, 6, Written);
Result:=LoadLibraryExW(lpLibFileName, hFile, dwFlags);
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[3].Entry, @DLLManager.RelockedInfo[3].InjectCode, 6, Written);
End;
end;

function NewGetProcAddress(hModule: HMODULE; lpProcName: LPCSTR): FARPROC; stdcall;
var
Written:Cardinal;
S:String;
begin
If not DLLManager.FIsActive Then Begin
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[4].Entry, @DLLManager.RelockedInfo[4].OldCode, 6, Written);
Result:=GetProcAddress(hModule, lpProcName);
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[4].Entry, @DLLManager.RelockedInfo[4].InjectCode, 6, Written);
End Else Begin
If (hModule>=Cardinal(@DLLManager.DLLInfo[0]))AND(hModule<=Cardinal(@DLLManager.DLLInfo[DLLManager.RDILen])) then begin
Result:=PDLLInfo(Pointer(hModule))^.Obj.FindExport(lpProcName);
Exit;
end;
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[4].Entry, @DLLManager.RelockedInfo[4].OldCode, 6, Written);
Result:=GetProcAddress(hModule, lpProcName);
WriteProcessMemory(GetCurrentProcess, DLLManager.RelockedInfo[4].Entry, @DLLManager.RelockedInfo[4].InjectCode, 6, Written);
End;
end;

constructor TDLLLoaderList.Create;
type
PPointer=^Pointer;
var
i:Integer;
Readed:Cardinal;
begin
Inherited;
RILen:=5;
SetLength(RelockedInfo, RILen);
RelockedInfo[0].Name:='LoadLibraryA'+#0;
RelockedInfo[0].Module:=LoadLibrary('kernel32.dll');
RelockedInfo[0].Entry:=GetProcAddress(RelockedInfo[0].Module, @RelockedInfo[0].Name[1]);
RelockedInfo[0].InjectCode[0]:=$68;
PPointer(@RelockedInfo[0].InjectCode[1])^:=@NewLoadLibraryA;
RelockedInfo[0].InjectCode[5]:=$C3;

RelockedInfo[1].Name:='LoadLibraryW'+#0;
RelockedInfo[1].Module:=LoadLibrary('kernel32.dll');
RelockedInfo[1].Entry:=GetProcAddress(RelockedInfo[1].Module, @RelockedInfo[1].Name[1]);
RelockedInfo[1].InjectCode[0]:=$68;
PPointer(@RelockedInfo[1].InjectCode[1])^:=@NewLoadLibraryW;
RelockedInfo[1].InjectCode[5]:=$C3;

RelockedInfo[2].Name:='LoadLibraryExA'+#0;
RelockedInfo[2].Module:=LoadLibrary('kernel32.dll');
RelockedInfo[2].Entry:=GetProcAddress(RelockedInfo[2].Module, @RelockedInfo[2].Name[1]);
RelockedInfo[2].InjectCode[0]:=$68;
PPointer(@RelockedInfo[2].InjectCode[1])^:=@NewLoadLibraryExA;
RelockedInfo[2].InjectCode[5]:=$C3;

RelockedInfo[3].Name:='LoadLibraryExW'+#0;
RelockedInfo[3].Module:=LoadLibrary('kernel32.dll');
RelockedInfo[3].Entry:=GetProcAddress(RelockedInfo[3].Module, @RelockedInfo[3].Name[1]);
RelockedInfo[3].InjectCode[0]:=$68;
PPointer(@RelockedInfo[3].InjectCode[1])^:=@NewLoadLibraryExW;
RelockedInfo[3].InjectCode[5]:=$C3;

RelockedInfo[4].Name:='GetProcAddress'+#0;
RelockedInfo[4].Module:=LoadLibrary('kernel32.dll');
RelockedInfo[4].Entry:=GetProcAddress(RelockedInfo[4].Module, @RelockedInfo[4].Name[1]);
RelockedInfo[4].InjectCode[0]:=$68;
PPointer(@RelockedInfo[4].InjectCode[1])^:=@NewGetProcAddress;
RelockedInfo[4].InjectCode[5]:=$C3;

For i:=0 to RILen - 1 do begin
ReadProcessMemory(GetCurrentProcess, RelockedInfo[i].Entry, @RelockedInfo[i].OldCode, 6, Readed);
WriteProcessMemory(GetCurrentProcess, RelockedInfo[i].Entry, @RelockedInfo[i].InjectCode, 6, Readed);
end;

RDILen:=0;
FIsActive:=False;
end;

destructor TDLLLoaderList.Destroy;
var
i:LongWord;
begin
IsActive:=False;
For i:=0 to RILen-1 do FreeLibrary(RelockedInfo[i].Module);
For i:=0 to RDILen-1 do DLLInfo[i].Obj.Free;
SetLength(RelockedInfo, 0);
SetLength(DLLInfo, 0);
Inherited;
end;

procedure TDLLLoaderList.AddDLLLoaderAs(Who:TDLLLoader; DllName:String);
begin
Inc(RDILen);
SetLength(DLLInfo, RDILen);
DLLInfo[RDILen - 1].Obj:=Who;
DLLInfo[RDILen - 1].Name:=DllName;
DLLInfo[RDILen - 1].Loaded:=0;
end;

initialization
DLLManager:=TDLLLoaderList.Create;
finalization
DLLManager.Free;
end.

И теперь загрузка Dll превращается в ещё более приятное занятие:

Код:

LoadResourceDll(HInstance, 'UNPACK', 'DLL', 'unrar.dll');
SetHookState(True);

После этого можно использовать LoadLibrary('unrar.dll') и GetProcAddres() с хендлом, возвращенным LoadLibrary, чего мы и добивались