/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef __GNUC__
// disable warnings about pointer <-> DWORD conversions
#  pragma warning(disable : 4311 4312)
#endif

#ifdef _WIN64
#  define POINTER_TYPE ULONGLONG
#else
#  define POINTER_TYPE DWORD
#endif

#include <windows.h>
#include <winnt.h>
#include <stdlib.h>
#ifdef DEBUG_OUTPUT
#  include <stdio.h>
#endif

#include "nsWindowsHelpers.h"

typedef const unsigned char* FileView;

template <>
class nsAutoRefTraits<FileView> {
 public:
  typedef FileView RawRef;
  static FileView Void() { return nullptr; }

  static void Release(RawRef aView) {
    if (nullptr != aView) UnmapViewOfFile(aView);
  }
};

#ifndef IMAGE_SIZEOF_BASE_RELOCATION
// Vista SDKs no longer define IMAGE_SIZEOF_BASE_RELOCATION!?
#  define IMAGE_SIZEOF_BASE_RELOCATION (sizeof(IMAGE_BASE_RELOCATION))
#endif

#include "LoadLibraryRemote.h"

typedef struct {
  PIMAGE_NT_HEADERS headers;
  unsigned char* localCodeBase;
  unsigned char* remoteCodeBase;
  HMODULE* modules;
  int numModules;
} MEMORYMODULE, *PMEMORYMODULE;

typedef BOOL(WINAPI* DllEntryProc)(HINSTANCE hinstDLL, DWORD fdwReason,
                                   LPVOID lpReserved);

#define GET_HEADER_DICTIONARY(module, idx) \
  &(module)->headers->OptionalHeader.DataDirectory[idx]

#ifdef DEBUG_OUTPUT
static void OutputLastError(const char* msg) {
  char* tmp;
  char* tmpmsg;
  FormatMessageA(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM |
                     FORMAT_MESSAGE_IGNORE_INSERTS,
                 nullptr, GetLastError(),
                 MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), (LPSTR)&tmp, 0,
                 nullptr);
  tmpmsg = (char*)LocalAlloc(LPTR, strlen(msg) + strlen(tmp) + 3);
  sprintf(tmpmsg, "%s: %s", msg, tmp);
  OutputDebugStringA(tmpmsg);
  LocalFree(tmpmsg);
  LocalFree(tmp);
}
#endif

static void CopySections(const unsigned char* data,
                         PIMAGE_NT_HEADERS old_headers, PMEMORYMODULE module) {
  int i;
  unsigned char* codeBase = module->localCodeBase;
  unsigned char* dest;
  PIMAGE_SECTION_HEADER section = IMAGE_FIRST_SECTION(module->headers);
  for (i = 0; i < module->headers->FileHeader.NumberOfSections;
       i++, section++) {
    dest = codeBase + section->VirtualAddress;
    memset(dest, 0, section->Misc.VirtualSize);
    if (section->SizeOfRawData) {
      memcpy(dest, data + section->PointerToRawData, section->SizeOfRawData);
    }
    // section->Misc.PhysicalAddress = (POINTER_TYPE) module->remoteCodeBase +
    //                                                section->VirtualAddress;
  }
}

static bool CopyRegion(HANDLE hRemoteProcess, void* remoteAddress,
                       void* localAddress, DWORD size, DWORD protect) {
  if (size > 0) {
    // Copy the data from local->remote and set the memory protection
    if (!VirtualAllocEx(hRemoteProcess, remoteAddress, size, MEM_COMMIT,
                        PAGE_READWRITE))
      return false;

    if (!WriteProcessMemory(hRemoteProcess, remoteAddress, localAddress, size,
                            nullptr)) {
#ifdef DEBUG_OUTPUT
      OutputLastError("Error writing remote memory.\n");
#endif
      return false;
    }

    DWORD oldProtect;
    if (VirtualProtectEx(hRemoteProcess, remoteAddress, size, protect,
                         &oldProtect) == 0) {
#ifdef DEBUG_OUTPUT
      OutputLastError("Error protecting memory page");
#endif
      return false;
    }
  }
  return true;
}
// Protection flags for memory pages (Executable, Readable, Writeable)
static int ProtectionFlags[2][2][2] = {
    {
        // not executable
        {PAGE_NOACCESS, PAGE_WRITECOPY},
        {PAGE_READONLY, PAGE_READWRITE},
    },
    {
        // executable
        {PAGE_EXECUTE, PAGE_EXECUTE_WRITECOPY},
        {PAGE_EXECUTE_READ, PAGE_EXECUTE_READWRITE},
    },
};

static bool FinalizeSections(PMEMORYMODULE module, HANDLE hRemoteProcess) {
#ifdef DEBUG_OUTPUT
  fprintf(stderr, "Finalizing sections: local base %p, remote base %p\n",
          module->localCodeBase, module->remoteCodeBase);
#endif

  int i;
  int numSections = module->headers->FileHeader.NumberOfSections;

  if (numSections < 1) return false;

  PIMAGE_SECTION_HEADER section = IMAGE_FIRST_SECTION(module->headers);

  // Copy any data before the first section (i.e. the image header)
  if (!CopyRegion(hRemoteProcess, module->remoteCodeBase, module->localCodeBase,
                  section->VirtualAddress, PAGE_READONLY))
    return false;

  // loop through all sections and change access flags
  for (i = 0; i < numSections; i++, section++) {
    DWORD protect, size;
    int executable = (section->Characteristics & IMAGE_SCN_MEM_EXECUTE) != 0;
    int readable = (section->Characteristics & IMAGE_SCN_MEM_READ) != 0;
    int writeable = (section->Characteristics & IMAGE_SCN_MEM_WRITE) != 0;

    // determine protection flags based on characteristics
    protect = ProtectionFlags[executable][readable][writeable];
    if (section->Characteristics & IMAGE_SCN_MEM_NOT_CACHED) {
      protect |= PAGE_NOCACHE;
    }

    void* remoteAddress = module->remoteCodeBase + section->VirtualAddress;
    void* localAddress = module->localCodeBase + section->VirtualAddress;

    // determine size of region
    size = section->Misc.VirtualSize;
#ifdef DEBUG_OUTPUT
    fprintf(stderr,
            "Copying section %s to %p, size %x, executable %i readable %i "
            "writeable %i\n",
            section->Name, remoteAddress, size, executable, readable,
            writeable);
#endif
    if (!CopyRegion(hRemoteProcess, remoteAddress, localAddress, size, protect))
      return false;
  }
  return true;
}

static void PerformBaseRelocation(PMEMORYMODULE module, SIZE_T delta) {
  DWORD i;
  unsigned char* codeBase = module->localCodeBase;

  PIMAGE_DATA_DIRECTORY directory =
      GET_HEADER_DICTIONARY(module, IMAGE_DIRECTORY_ENTRY_BASERELOC);
  if (directory->Size > 0) {
    PIMAGE_BASE_RELOCATION relocation =
        (PIMAGE_BASE_RELOCATION)(codeBase + directory->VirtualAddress);
    for (; relocation->VirtualAddress > 0;) {
      unsigned char* dest = codeBase + relocation->VirtualAddress;
      unsigned short* relInfo = (unsigned short*)((unsigned char*)relocation +
                                                  IMAGE_SIZEOF_BASE_RELOCATION);
      for (i = 0;
           i < ((relocation->SizeOfBlock - IMAGE_SIZEOF_BASE_RELOCATION) / 2);
           i++, relInfo++) {
        DWORD* patchAddrHL;
#ifdef _WIN64
        ULONGLONG* patchAddr64;
#endif
        int type, offset;

        // the upper 4 bits define the type of relocation
        type = *relInfo >> 12;
        // the lower 12 bits define the offset
        offset = *relInfo & 0xfff;

        switch (type) {
          case IMAGE_REL_BASED_ABSOLUTE:
            // skip relocation
            break;

          case IMAGE_REL_BASED_HIGHLOW:
            // change complete 32 bit address
            patchAddrHL = (DWORD*)(dest + offset);
            *patchAddrHL += delta;
            break;

#ifdef _WIN64
          case IMAGE_REL_BASED_DIR64:
            patchAddr64 = (ULONGLONG*)(dest + offset);
            *patchAddr64 += delta;
            break;
#endif

          default:
            // printf("Unknown relocation: %d\n", type);
            break;
        }
      }

      // advance to next relocation block
      relocation = (PIMAGE_BASE_RELOCATION)(((char*)relocation) +
                                            relocation->SizeOfBlock);
    }
  }
}

static int BuildImportTable(PMEMORYMODULE module) {
  int result = 1;
  unsigned char* codeBase = module->localCodeBase;

  PIMAGE_DATA_DIRECTORY directory =
      GET_HEADER_DICTIONARY(module, IMAGE_DIRECTORY_ENTRY_IMPORT);
  if (directory->Size > 0) {
    PIMAGE_IMPORT_DESCRIPTOR importDesc =
        (PIMAGE_IMPORT_DESCRIPTOR)(codeBase + directory->VirtualAddress);
    PIMAGE_IMPORT_DESCRIPTOR importEnd = (PIMAGE_IMPORT_DESCRIPTOR)(
        codeBase + directory->VirtualAddress + directory->Size);

    for (; importDesc < importEnd && importDesc->Name; importDesc++) {
      POINTER_TYPE* thunkRef;
      FARPROC* funcRef;
      HMODULE handle = GetModuleHandleA((LPCSTR)(codeBase + importDesc->Name));
      if (handle == nullptr) {
#if DEBUG_OUTPUT
        OutputLastError("Can't load library");
#endif
        result = 0;
        break;
      }

      module->modules = (HMODULE*)realloc(
          module->modules, (module->numModules + 1) * (sizeof(HMODULE)));
      if (module->modules == nullptr) {
        result = 0;
        break;
      }

      module->modules[module->numModules++] = handle;
      if (importDesc->OriginalFirstThunk) {
        thunkRef = (POINTER_TYPE*)(codeBase + importDesc->OriginalFirstThunk);
        funcRef = (FARPROC*)(codeBase + importDesc->FirstThunk);
      } else {
        // no hint table
        thunkRef = (POINTER_TYPE*)(codeBase + importDesc->FirstThunk);
        funcRef = (FARPROC*)(codeBase + importDesc->FirstThunk);
      }
      for (; *thunkRef; thunkRef++, funcRef++) {
        if (IMAGE_SNAP_BY_ORDINAL(*thunkRef)) {
          *funcRef =
              (FARPROC)GetProcAddress(handle, (LPCSTR)IMAGE_ORDINAL(*thunkRef));
        } else {
          PIMAGE_IMPORT_BY_NAME thunkData =
              (PIMAGE_IMPORT_BY_NAME)(codeBase + (*thunkRef));
          *funcRef = (FARPROC)GetProcAddress(handle, (LPCSTR)&thunkData->Name);
        }
        if (*funcRef == 0) {
          result = 0;
          break;
        }
      }

      if (!result) {
        break;
      }
    }
  }

  return result;
}

static void* MemoryGetProcAddress(PMEMORYMODULE module, const char* name);

void* LoadRemoteLibraryAndGetAddress(HANDLE hRemoteProcess,
                                     const WCHAR* library, const char* symbol) {
  // Map the DLL into memory
  nsAutoHandle hLibrary(CreateFile(library, GENERIC_READ, FILE_SHARE_READ,
                                   nullptr, OPEN_EXISTING,
                                   FILE_ATTRIBUTE_NORMAL, nullptr));
  if (INVALID_HANDLE_VALUE == hLibrary) {
#if DEBUG_OUTPUT
    OutputLastError("Couldn't CreateFile the library.\n");
#endif
    return nullptr;
  }

  nsAutoHandle hMapping(
      CreateFileMapping(hLibrary, nullptr, PAGE_READONLY, 0, 0, nullptr));
  if (!hMapping) {
#if DEBUG_OUTPUT
    OutputLastError("Couldn't CreateFileMapping.\n");
#endif
    return nullptr;
  }

  nsAutoRef<FileView> data(
      (const unsigned char*)MapViewOfFile(hMapping, FILE_MAP_READ, 0, 0, 0));
  if (!data) {
#if DEBUG_OUTPUT
    OutputLastError("Couldn't MapViewOfFile.\n");
#endif
    return nullptr;
  }

  SIZE_T locationDelta;

  PIMAGE_DOS_HEADER dos_header = (PIMAGE_DOS_HEADER)data.get();
  if (dos_header->e_magic != IMAGE_DOS_SIGNATURE) {
#if DEBUG_OUTPUT
    OutputDebugStringA("Not a valid executable file.\n");
#endif
    return nullptr;
  }

  PIMAGE_NT_HEADERS old_header =
      (PIMAGE_NT_HEADERS)(data + dos_header->e_lfanew);
  if (old_header->Signature != IMAGE_NT_SIGNATURE) {
#if DEBUG_OUTPUT
    OutputDebugStringA("No PE header found.\n");
#endif
    return nullptr;
  }

  // reserve memory for image of library in this process and the target process
  unsigned char* localCode = (unsigned char*)VirtualAlloc(
      nullptr, old_header->OptionalHeader.SizeOfImage, MEM_RESERVE | MEM_COMMIT,
      PAGE_READWRITE);
  if (!localCode) {
#if DEBUG_OUTPUT
    OutputLastError("Can't reserve local memory.");
#endif
  }

  unsigned char* remoteCode = (unsigned char*)VirtualAllocEx(
      hRemoteProcess, nullptr, old_header->OptionalHeader.SizeOfImage,
      MEM_RESERVE, PAGE_EXECUTE_READ);
  if (!remoteCode) {
#if DEBUG_OUTPUT
    OutputLastError("Can't reserve remote memory.");
#endif
  }

  MEMORYMODULE result;
  result.localCodeBase = localCode;
  result.remoteCodeBase = remoteCode;
  result.numModules = 0;
  result.modules = nullptr;

  // copy PE header to code
  memcpy(localCode, dos_header,
         dos_header->e_lfanew + old_header->OptionalHeader.SizeOfHeaders);
  result.headers =
      reinterpret_cast<PIMAGE_NT_HEADERS>(localCode + dos_header->e_lfanew);

  // update position
  result.headers->OptionalHeader.ImageBase = (POINTER_TYPE)remoteCode;

  // copy sections from DLL file block to new memory location
  CopySections(data, old_header, &result);

  // adjust base address of imported data
  locationDelta = (SIZE_T)(remoteCode - old_header->OptionalHeader.ImageBase);
  if (locationDelta != 0) {
    PerformBaseRelocation(&result, locationDelta);
  }

  // load required dlls and adjust function table of imports
  if (!BuildImportTable(&result)) {
    return nullptr;
  }

  // mark memory pages depending on section headers and release
  // sections that are marked as "discardable"
  if (!FinalizeSections(&result, hRemoteProcess)) {
    return nullptr;
  }

  return MemoryGetProcAddress(&result, symbol);
}

static void* MemoryGetProcAddress(PMEMORYMODULE module, const char* name) {
  unsigned char* localCodeBase = module->localCodeBase;
  int idx = -1;
  DWORD i, *nameRef;
  WORD* ordinal;
  PIMAGE_EXPORT_DIRECTORY exports;
  PIMAGE_DATA_DIRECTORY directory =
      GET_HEADER_DICTIONARY(module, IMAGE_DIRECTORY_ENTRY_EXPORT);
  if (directory->Size == 0) {
    // no export table found
    return nullptr;
  }

  exports =
      (PIMAGE_EXPORT_DIRECTORY)(localCodeBase + directory->VirtualAddress);
  if (exports->NumberOfNames == 0 || exports->NumberOfFunctions == 0) {
    // DLL doesn't export anything
    return nullptr;
  }

  // search function name in list of exported names
  nameRef = (DWORD*)(localCodeBase + exports->AddressOfNames);
  ordinal = (WORD*)(localCodeBase + exports->AddressOfNameOrdinals);
  for (i = 0; i < exports->NumberOfNames; i++, nameRef++, ordinal++) {
    if (stricmp(name, (const char*)(localCodeBase + (*nameRef))) == 0) {
      idx = *ordinal;
      break;
    }
  }

  if (idx == -1) {
    // exported symbol not found
    return nullptr;
  }

  if ((DWORD)idx > exports->NumberOfFunctions) {
    // name <-> ordinal number don't match
    return nullptr;
  }

  // AddressOfFunctions contains the RVAs to the "real" functions
  return module->remoteCodeBase +
         (*(DWORD*)(localCodeBase + exports->AddressOfFunctions + (idx * 4)));
}